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Amelia Earhart Search Forum => Aircraft & Powerplant, Performance and Operations => Topic started by: Gary LaPook on November 26, 2011, 12:45:47 PM

Title: FAQ: Octane Analysis
Post by: Gary LaPook on November 26, 2011, 12:45:47 PM

Let's see, 2 tanks with 2 gallons more equals 4 gallons.  Assuming 40 gallons per hour fuel management, that represents 1/10th hour or 6 minutes which, at 133 mph represents about 13 miles.  Could be the difference between getting wet and landing on a reef.
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Yep, that may be true but nobody would take the wings apart to add just four gallons to the existing 1147 gallons because nobody would ever expect that the pilot would make a flight, cutting it that close on fuel.

gl
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on November 26, 2011, 01:33:25 PM

Let's see, 2 tanks with 2 gallons more equals 4 gallons.  Assuming 40 gallons per hour fuel management, that represents 1/10th hour or 6 minutes which, at 133 mph represents about 13 miles.  Could be the difference between getting wet and landing on a reef.
--------------------------
Yep, that may be true but nobody would take the wings apart to add just four gallons to the existing 1147 gallons because nobody would ever expect that the pilot would make a flight, cutting it that close on fuel.

gl

Let's see, 2 tanks with 2 gallons more equals 4 gallons.  Assuming 40 gallons per hour fuel management, that represents 1/10th hour or 6 minutes which, at 133 mph represents about 13 miles.  Could be the difference between getting wet and landing on a reef.
--------------------------
Yep, that may be true but nobody would take the wings apart to add just four gallons to the existing 1147 gallons because nobody would ever expect that the pilot would make a flight, cutting it that close on fuel.

gl

Gary
Yep, but that pilot took off with an 81 gallon tank only half full.  The 40.5 additional gallons might have given an additional 1 hour's endurance (133 miles)  Oh well, can't  mix octanes.
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on November 26, 2011, 04:01:36 PM

Jeff
I don't think AE was much concerned with range.  The Lockheed estimate with 1200 gallons was 4100 to 4500 miles.  Doing a simple ratio with 1100/1200 reduces that to 3700  to 4100 or so, still far above the Lae- Howland distance of 2600 or so.

So, the 40.5 gallons left behind wasn't too important, but three things that a pilot has no need for are 1. Altitude above the plane, 2. Runway behind the plane, and gas left in the fill truck.
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on November 28, 2011, 11:32:05 AM

Of course octanes can be mixed, and I'll never understand why the 81 gallon tank wasn't filled with 80 octane before takeoff .  That extra 40.5 gallons could have meant an additional 1 hour's flight should it have become necessary.  As I said before, gas in a truck at an airfield behind you is of no use to a pilot looking for a tiny sliver of an ialand in a large ocean.
The number of flat-out stupid errors made on that leg were just astounding.
Title: Re: Octane Analysis
Post by: Mona Kendrick on November 28, 2011, 10:16:01 PM
I spent a little while this evening looking for Lae's runway length and can't seem to find any sources -- but I do seem to recall once reading that it was about 3000 ft.  In any case, it was barely long enough for such a heavily loaded takeoff as NR16020's; the takeoff run used virtually every bit of runway, as described by witnesses.  Diluting the 100 octane by adding 40.5 gallons 80 octane would have reduced the power for takeoff and added 246 lb. of weight (40.5 gal. X 6 lb./gal. = 246), thus increasing the length of takeoff roll needed to get off the ground.  In short, insufficient runway is probably why she didn't top off the 81 gal. tank with 80 octane.

LTM,
Mona
Title: Re: Octane Analysis
Post by: Gary LaPook on November 29, 2011, 10:11:37 AM

Of course octanes can be mixed, and I'll never understand why the 81 gallon tank wasn't filled with 80 octane before takeoff .  That extra 40.5 gallons could have meant an additional 1 hour's flight should it have become necessary.  As I said before, gas in a truck at an airfield behind you is of no use to a pilot looking for a tiny sliver of an ialand in a large ocean.
The number of flat-out stupid errors made on that leg were just astounding.

In terms of 'range' and best habit, you are spot on - the fuel in the truck, like the runway behind you on an intersection take-off and the altitude above you can't help you once committed to the wilderness of the air.

But, in terms of take-off performance / power requirements, you can't mix octanes - the 100 would be needed for max power at take-off.  I don't think 100 was available at Lae to top off that particular tank; had it been, the additional fuel that would have been left after take-off would have padded the range capability that much more since 100 octane can also be used at any other time (it's just overkill at lower power settings).

Mona Kendrick's point below yours is a good analysis of the fix AE would have been in had she diluted her existing 100 octane supply for the sake of topped-off tanks.  Her point, and yours earlier that plenty of range was actually already afforded by the 1050 +/- gallons aboard at take-off bear out AE's reasoning.  Given that sufficient range was provided for as AE and FN likely saw it, it probably would have been a relative no-brainer to go with a partial load of 100 octane aboard.

LTM -
--------------------------

The engines could be run on either 80 octane or 100 octane fuel. How much horsepower did they make with the 80 octane and how much horsepower did they make with the 100 octane?

gl
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on November 29, 2011, 11:29:12 AM

I agree with the points above.  Now, I'll pick some nits.
Assume that they took off with about 1110 gallons, which at 6 lbs per gallon represents a fuel load of 6660 lbs, then the additional 243 pounds (40.5 x 6=243) would represent an increase of about 3.65%.  The plane, passengers, baggage, etc weighed something (Probably as much as the fuel) so the additional 40.5 gallons probably represented less than 2% more.  If they were cutting the weight/takeoff roll that close that an additional 2% would have mattered then they picked the wrong runway.

Gas left behind on a truck at the airfield is of no use.
Title: Re: Octane Analysis
Post by: Gary LaPook on November 29, 2011, 12:46:37 PM
Now you've heard about all I know on AvGas - just enough to be dangerous...
----------------------------------

I have attached TCDC 590, can you point out where is requires the use of 100 octane fuel to get the 550 hp takeoff power?

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on November 29, 2011, 03:57:46 PM
Gary, in this case, the aircraft TCDS does not specify minimum octanes.  You can find that information in the Wasp S3H1 engine TCDS E-143.  Minimum octane there is shown as 80/87, and if you follow the tables and relevant note 5 it gets you to a 91/96 octane requirement for certain higher power settings at sea level (600 HP for 5 minutes).
LTM -
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Take a close look at note 5 of TCDS E-143, which I have attached. You will see that there is NO increase in power when higher octane fuel is used. The engine was designed and certified to put out the full takeoff power rating of 600 hp using 80/87 fuel. Note, that in order to get the same 600 hp using 91/96 octane fuel you must increase the manifold pressure a half an inch compared to setting takeoff power using 80/87. By the end of WW2 there were four grades of avgas, 80/87; 91/96; 100/130 and 115/145 so "91/96" does not mean 100 octane in the TCDS.

I have represented Pratt & Whitney and UT including Sikorsky for many years and if they could have gotten more horsepower out of the engines by simply increasing the octane required they would have, since they could have then have sold the engines for more money. Prior to WW2 100 octane fuel was very new. I watched a show about the Doolittle raid and learned that after Doolittle left active duty in 1929 he worked for Shell Oil. Doolittle believed that more powerful engines were needed for modern military planes. At his instigation Shell Oil developed 100 octane fuel so that these more powerful engines could be developed. Shell delivered the first load of 100 octane fuel to the Army Air Corps for test purposes in 1934. In 1937 100 octane was very rare but when the TCDS was last amended, 100 octane was ubiquitous so, if 100 octane would have produced more takeoff power, why didn't P&W amend the TCDS to provide for the use of 100 octane? If you look at all the TCDS for P&W round engines you will find NONE that allow for a higher power output when higher octane fuel is used. There are 107 variants of the Wasp engine, including the military R1340 versions. Of all these variants only one specified the use of 100 octane fuel, the R1340-37, which is a geared engine. There are extensive differences between it and Earhart's engines including a strengthened head and fuel injection, a higher compression ratio and greater supercharger ratio. Note, even with these extensive improvements and the use of 100 octane fuel, the engine still only produced 600 hp. The main improvement from all these changes was raising the critical altitude all the way up to 11,000 feet.

gl
Title: Re: Octane Analysis
Post by: John Ousterhout on November 29, 2011, 08:05:56 PM
http://tighar.org/Projects/Earhart/Archives/Research/Bulletins/27_LaeGallery/27_LaeGallery.html gives the Lae runway length as 3000 feet.
I corrected my earlier post shortly after re-reading it, but Gary beat me to it. Sorry for any confusion.
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on November 29, 2011, 09:43:41 PM

Mona
Sorry, My Bad, Apologies     Reply #33 was about Howland,  Lae had 1 runway  3000 feet.  Looks to be oriented NW to SE  150 degrees  runway numbered 15 and33.

The additional 243 lbs could possibly have affected the takeoff roll and since she had 1110.5 gallons and plenty of range (endurance) for the proposed leg it was probably prudent to go without the 40.5 gallons.  I might have considered gassing up and leaving Fred behind.  MHO
Title: Re: Octane Analysis
Post by: Gary LaPook on November 30, 2011, 03:15:04 PM
Thanks Marty.  As soon as I can I'll brush up on minimizing my clutter - sorry.

For now -

Gary LaPook - "Take a close look at note 5 of TCDS E-143, which I have attached. You will see that there is NO increase in power when higher octane fuel is used. The engine was designed and certified to put out the full takeoff power rating of 600 hp using 80/87 fuel. Note, that in order to get the same 600 hp using 91/96 octane fuel you must increase the manifold pressure a half an inch compared to setting takeoff power using 80/87. By the end of WW2 there were four grades of avgas, 80/87; 91/96; 100/130 and 115/145 so "91/96" does not mean 100 octane in the TCDS."

And again, "increasing octane does not increase power" anyway - it merely allows one to safely apply power settings that create the highest combustion chamber pressures - to obtain the highest power output.  How?  By resistance to detonation and preignition that is more prevalent in the use of less-buffered / more volatile fuels.

Consider Note 5 again - it says (verbatim) -

(a) Ratings are based upon the best mixture strength and 450F cylinder head temperature.
(b) With the use of grade 91/96 fuel, the following ratings may be used:

Maximum continuous, hp, rpm, in.Hg., at:
- Critical altitude (ft.)                                   550-2200-33.0-4500
- Sea level pressure altitude (ft.)                  550-2200-34.0-S.L.
Takeoff (one minute), hp, rpm, in.Hg., at:
- Critical altitude (ft.)                                   600-2250-36.0-2300
- Sea level pressure altitude (ft.)                  600-2250-36.5-S.L.
[/u]
LTM -

However, the main data on page 1 states, verbatim:

Maximum continuous, hp, rpm, in.Hg., at:
- Critical altitude (ft.)                                   550-2200-32.5-5000
- Sea level pressure altitude (ft.)                    550-2200-34.0-S.L.
Takeoff (five minutes), hp, rpm, in.Hg., at:
- Critical altitude (ft.)                                   600-2250-35.5-3000
- Sea level pressure altitude (ft.)                    600-2250-36.0-SL (See note 5.)

There are three ways to show that your interpretation is in error. First you claim that the 91/96 octane is only needed for 600 hp takeoff power but note 5 also shows power settings for continuous power. If you were correct, then by your logic, 91/96 was also necessary for the continuous rating of 550 hp.

Second, note 5 shows a higher mp necessary, 36.5 inches, to obtain takeoff power using 91/96 compared to only 36.0 inches on page one. Just what do you think the 36.0 inch setting on page 1 is referring to? It is referring to the use of 80/87 to obtain takeoff power. If this were not true then page one would omit a power setting for full power and simply refer to note 5. I pointed out the difference in manifold pressure settings in my prior post, I'm surprised that you didn't pick up on this.

Third, note that the time limit for takeoff power is one minute when using 91/96 (note 5) while the limit when using 80/87 for takeoff shown on page is five minutes. Again, this would be omitted if you couldn't produce takeoff power with 80/87. And the lower time limit when using 91/96 makes sense since you are using a higher mp.

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on November 30, 2011, 04:35:20 PM
Gary, you are ignoring Note 5's full import - and the greater meaning of this discussion -

The whole point is: the higher octane is required for the highest power settings - period.

My whole point is that higher octane was NOT required for the highest power settings.
Quote

- and after 35 years of dealing with authorities on this stuff it is clear what the answer would be
I've spent over 20 years dealing with these things too, working with IAs, A&Ps and factory engineers at P&W so I think I am qualified to interpret this TCDS too and I don't see any ambiguity at all.
Quote

So, I guess we disagree, no loss, but I suggest keeping your 91/96 octane handy...  :D
- Jeff

I am attaching the P&W power setting table for the S3H1 engine that shows settings for the 600 hp takeoff power for both 80/87 octane and for 91/96 octane and these setting are the same settings as the settings in the TCDS, the 80/87 settings from page 1 and the 91/96 settings from note 5. This power setting table confirms my interpretation of the TCDS and refutes yours.

You didn't respond to my three points either but if you don't want to, then I will drop this conversation too. We have stated our arguments and I have posted my source documents so readers can decide for themselves which point is more convincing. :D

gl
Title: Re: Octane Analysis
Post by: John Ousterhout on November 30, 2011, 07:19:26 PM
I take gary's point to be that the half-full 100-octane tank could have been safely topped up with 87 octane, without endangering the takeoff from Lae or Howland.  The connection with NOT landing on Nikumororo is a little harder to see, and I trust he will clarify shortly.
I actually enjoyed the technical treatise, even if slightly off topic.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 01, 2011, 03:15:15 AM
I take gary's point to be that the half-full 100-octane tank could have been safely topped up with 87 octane, without endangering the takeoff from Lae or Howland.
That is my point and the extra hour of flight endurance could have allowed Earhart to find Howland, or some other island or, if she landed on Nikumororo then the extra fuel would have provided many hours of extra radio transmitting time, take your pick.
Quote
The connection with NOT landing on Nikumororo is a little harder to see, and I trust he will clarify shortly.
I actually enjoyed the technical treatise, even if slightly off topic.
Not connected with the landing on Nikumororo, an example of "thread drift."
gl
Title: Re: Octane Analysis
Post by: Gary LaPook on December 04, 2011, 01:59:54 AM
First though, since you disagreed, I'll repeat: "higher octane is required for the highest power settings" -
Somehow that seems fundamental enough to "our points" that I'll close with a summary on "why this is so", after what immediately follows:

As to your more immediate "3 points" -

GL-

In my experience, the more conservative reading (the NOTE) is the one the operator is bound to live by (one case of "the Note taketh away").

GL -
"Second, note 5 shows a higher mp necessary, 36.5 inches, to obtain takeoff power using 91/96 compared to only 36.0 inches on page one. Just what do you think the 36.0 inch setting on page 1 is referring to? It is referring to the use of 80/87 to obtain takeoff power. If this were not true then page one would omit a power setting for full power and simply refer to note 5. I pointed out the difference in manifold pressure settings in my prior post, I'm surprised that you didn't pick up on this."

I think it refers to 600 HP at 2250 RPM 36.0" MP at Sea Level for 5 minutes, no disagreement on that.  But it's not the "highest power setting" available.  Not sure I even challenged that per se, but if I slipped into it then "you win".
You suggest that were my foolishness true, "page one would omit a power setting for full power and simply refer to note 5" - really?  Is that a "full power" setting when a higher one is available?  I disagree.  ;D

GL -
"Third, note that the time limit for takeoff power is one minute when using 91/96 (note 5) while the limit when using 80/87 for takeoff shown on page is five minutes. Again, this would be omitted if you couldn't produce takeoff power with 80/87. And the lower time limit when using 91/96 makes sense since you are using a higher mp."

And as promised, to in sum to "higher octane is required for the highest power settings" -
"Just what do you think" the "highest power settings" are?
The "highest power settings" involve the highest combustion pressures - and, again, the data is clear (from the now notorious "Note 5"):
-  Takeoff (one minute), hp, rpm, in.Hg., at:
Crit Alt (ft.)                     600-2250-36.0-2300
S/L Press Alt (ft.)            600-2250-36.5-S.L.
Gary, those ARE the "highest power settings" on the TCDS (look at the pressures and relevant altitudes - that's the key), and per poor ol' TCDS E-143 Rev. 4 (1973, mind you...) those settings DO require "higher octane" fuel, namely 91/96 octane. ;)

You have claimed that there is a general rule for interpreting a TCDS that  "the note taketh away" and you rely on this to surmise that note 5 "taketh away" the power setting for takeoff power using  80/87 octane printed on page 1 and instead requires that, to obtain 600 hp takeoff power, you must only use the settings in note 5 including using 91/96 octane fuel. I was going to attach a bunch of other TCDS's to show that there are many notes that do not "taketh away" but I realized that this was not necessary. There are actually 6 notes on TCDS E-143 for Earhart's engines that we have been examining and none of the six "taketh away" anything and that includes note 5. Take a look at them.

I think I see where you went wrong and it is entirely understandable, every pilot that has flown behind a constant speed prop would probably make the same error. You see that the manifold pressure in note 5 is higher than the manifold pressure on page 1 and you said to yourself "aha, higher manifold pressure means more power!" As I said, I think every other pilot would say the same thing.

I'm sure you know this, so I expect to hear a loud noise when you slap yourself on the forehead. Carburettors meter fuel based on volume not on weight but the power output of the engine is not determined by the volume of fuel but by the weight of the fuel that goes through the engine every second. I have attached a 1944 Army Air Force graph showing the density of various grades of aviation fuel. 87 octane is denser than the other grades. At 30° C 87 octane has a density of 5.97 pounds per gallon while 95 octane is only 5.78 pounds per gallon. Although pilots' normal experience shows increasing power with increasing manifold pressure those pilots do not have experience with switching to a grade of AVGAS that has a lower density. The TCDS shows that you have to use higher manifold pressure with 91/96 in order to force a greater volume of fuel through the carburettors in order to supply the same weight of fuel per second so as to produce the 600 hp that could be produced with a lower manifold pressure using the denser 87 octane fuel.

I have also attached the Pratt & Whitney power setting table for this engine. You will note that it takes an additional gallon (volume) per hour using 91/96 octane low density fuel to move the same weight of fuel through the carburettors every hour to produce the same 100% power and the same takeoff power as when using 80/87 octane high density fuel. This confirms that the extra half inch of manifold pressure is needed to compensate for the lower density of the 91/96 fuel and its use does not lead to a higher power output.

(Also, you seem to ignore the "600" at the beginning of the takeoff power settings in note 5, and this "600" means 600 hp, the same as the 600 hp when using the power settings on page 1 for 80/87 octane.)

gl
Title: Re: Octane Analysis
Post by: Richard C Cooke on December 04, 2011, 06:45:15 AM
I'm sure you know this, so I expect to hear a loud noise when you slap yourself on the forehead. Carburettors meter fuel based on volume not on weight but the power output of the engine is not determined by the volume of fuel but by the weight of the fuel that goes through the engine every second. I have attached a 1944 Army Air Force graph showing the density of various grades of aviation fuel. 87 octane is denser than the other grades. At 30° C 87 octane has a density of 5.97 pounds per gallon while 95 octane is only 5.78 pounds per gallon. Although pilots' normal experience shows increasing power with increasing manifold pressure those pilots do not have experience with switching to a grade of AVGAS that has a lower density. The TCDS shows that you have to use higher manifold pressure with 91/96 in order to force a greater volume of fuel through the carburettors in order to supply the same weight of fuel per second so as to produce the 600 hp that could be produced with a lower manifold pressure using the denser 87 octane fuel.
gl
That would be correct if you had no mixture control.  The manifold pressure determines how much air goes in and the mixture control on the carburetor determines how much fuel goes in.  So to get the desired air fuel ratio with the low density fuel, the mixture the control lever would have to be set slightly towards the rich side compared to its position when using the high density fuel.

Richard Cooke
Title: Re: Octane Analysis
Post by: Richard C Cooke on December 04, 2011, 09:34:17 AM
Here is a NACA report from March 1938 that shows what they saw as the benefits of various fuel grades.

Interestingly they got their various ratings by blending 100 octane fuel with 18 (yes 18 octane) "fuel" in appropriate proportions.

Richard Cooke
Title: Re: Octane Analysis
Post by: Gary LaPook on December 04, 2011, 11:52:00 AM
I'm sure you know this, so I expect to hear a loud noise when you slap yourself on the forehead. Carburettors meter fuel based on volume not on weight but the power output of the engine is not determined by the volume of fuel but by the weight of the fuel that goes through the engine every second. I have attached a 1944 Army Air Force graph showing the density of various grades of aviation fuel. 87 octane is denser than the other grades. At 30° C 87 octane has a density of 5.97 pounds per gallon while 95 octane is only 5.78 pounds per gallon. Although pilots' normal experience shows increasing power with increasing manifold pressure those pilots do not have experience with switching to a grade of AVGAS that has a lower density. The TCDS shows that you have to use higher manifold pressure with 91/96 in order to force a greater volume of fuel through the carburettors in order to supply the same weight of fuel per second so as to produce the 600 hp that could be produced with a lower manifold pressure using the denser 87 octane fuel.
gl
That would be correct if you had no mixture control.  The manifold pressure determines how much air goes in and the mixture control on the carburetor determines how much fuel goes in.  So to get the desired air fuel ratio with the low density fuel, the mixture the control lever would have to be set slightly towards the rich side compared to its position when using the high density fuel.

Richard Cooke
EXCEPT that the mixture control  is set to its maximum position for all takeoffs (unless from a high altitude airport, Lae was not a high altitude airport) so there is no way to make the mixture richer if switching to lower density fuel, it is already maxed out for 80/87 octane fuel. Because of this you cannot increase the mass flow through the carbs to compensate for the lower density fuel by use of the mixture control, that is why you need the higher manifold pressure.

The full rich position on an aircraft carburetor is equivalent to the normal carburetor in a car. The mixture control on an aircraft carburetor "leans" the mixture from that point for flight at altitude, it cannot "enrichen" the fuel air mixture any farther. To help you understand this I have attached an excerpt from the P&W maintenance manual for Earhart's S3H1 engines that describes the mixture control. There is a diagram included of the NA-R9B carburetor but this is NOT the type that was used on the Wasp engine, the manual also covers the Wasp Jr. engine and this is the carburetor for that engine. There is no diagram of the NA-Y9H installed on Earhart's Wasp engines. I have also included an excerpt from the FAA A&P Mechanics Powerplant Handbook that describes the action of the type of mixture control used on Earhart's engines.

gl

Title: Re: Octane Analysis
Post by: Gary LaPook on December 04, 2011, 11:54:30 AM
Here is a NACA report from March 1938 that shows what they saw as the benefits of various fuel grades.

Interestingly they got their various ratings by blending 100 octane fuel with 18 (yes 18 octane) "fuel" in appropriate proportions.

Richard Cooke
Interesting, but the report only deals with the anti-knock properties of aviation fuel, it does not address the issue we are discussing, the difference in power output due to different densities.

gl
Title: Re: Octane Analysis
Post by: JNev on December 06, 2011, 05:46:42 AM
Gary, I didn't "get it wrong" - there are "reasons" the higher octane is imposed where the "highest numbers" are involved -

Higher MP among other constants = higher combustion pressures.

The highest combustion pressures (at the highest MP settings) = requirement for 100 octane.

That's the point.

"Mixture" has little to do with it, although that statement alone could easily provoke several pages of argument.  The ratings involve "full (or auto) rich".

"Octane" has little to do with density in the sense you speak of either; it has everything to do with suppression of "knock".  The physics are true, at the nano level - but at the practical level YOU NEED THE OCTANE TO USE THE MAX ATTAINABLE PRESSURES.  Torturing the data doesn't change that.

---

Richard, excellent find - thanks for sharing that.

I HIGHLY recommend the reading of that NACA report (link in Richard's post above) for those who honestly want to understand the effects of octane on power extraction from the internal combustion engine (Wasp included) - this drives exactly at the point I have struggled make in this string.  Don't take my word for anything, read it and see for yourselves if interested.

LTM -
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 06, 2011, 11:21:53 AM

The issue that we were initially discussing was the question:  IF the 81 gallon tank that contained about 40.5 gallons of 100 octane fuel had been "topped off" with 40.5 gallons of 80/87 octane fuel, THEN would the distance to takeoff have been appreciably lengthened?
Title: Re: Octane Analysis
Post by: Martin X. Moleski, SJ on December 06, 2011, 03:33:20 PM
I believe that was before we dove into the weeds and the topic got (sensibly) split off.

Marty has uncommon good sense on when to do that ...

Thanks for the compliment, but it is undeserved.

Someone sent me a message in the background, suggesting the split.

I do not have much sensitivity to thread drift.  I contribute to it regularly.   :(

Quote
- and seemingly infinite patience -

That is also an illusion.  I am often busy with other things--especially these days at the end of the semester.   ::)
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 07, 2011, 06:22:03 AM
If AE was flying with one tank of 100 octane because she had been told or led to believe she needed it for extra power on takeoff then why would she have that tank topped up with non 100 octane. She believed she had plenty of fuel, with ample reserve, for the trip to Howland.
She did know that Howland's airstrip had just been constructed and has no idea what shape it was really in. So saving any 100 octane for a "boosted" takeoff on a new runway on a small island would have been prudent. She didn't plan on getting lost and needing every tank to be 100% full.  But she did need to plan her takeoff from Howland. If some of the arguments/inferences in this thread are true then why was she carrying two types of octane in the first place?
Title: Re: Octane Analysis
Post by: Gary LaPook on December 07, 2011, 10:52:04 AM
If AE was flying with one tank of 100 octane because she had been told or led to believe she needed it for extra power on takeoff then why would she have that tank topped up with non 100 octane. She believed she had plenty of fuel, with ample reserve, for the trip to Howland.
She did know that Howland's airstrip had just been constructed and has no idea what shape it was really in. So saving any 100 octane for a "boosted" takeoff on a new runway on a small island would have been prudent. She didn't plan on getting lost and needing every tank to be 100% full.  But she did need to plan her takeoff from Howland. If some of the arguments/inferences in this thread are true then why was she carrying two types of octane in the first place?
Because she was misinformed. High octane fuel is needed in high compression engines to prevent detonation (knock) that can quickly damage the engine. Earhart's S3H1 engines are low compression engines with a compression ratio of only 6:1, designed to make full takeoff power with the 87 octane fuel available at Lae. One hundred octane fuel only became available, in experimental quantities, in 1934. The S3H1 had been designed to use the existing 87 octane fuel because it takes a lot longer than the one or two years that 100 octane fuel was available, prior to the actual construction of her engines, to design a new aircraft engine. Only one of the 107 other versions of the Wasp engine, many designed during WW2 after 100 octane fuel was freely available, required the use of 100 octane fuel and even that one version only put out 600 hp, just like Earhart's engines. (That one engine type was fuel injected and had many other modifications.) Think about it, there was a lot of pressure and incentive for Pratt & Whitney to increase the power of these engines, ("don't you know, there's a war on") but they were unable to do so even when 100 octane and other even higher octane fuels were available, all the way up to 145 octane.
Ask all of your friends and I bet that they will all say the same thing, that putting high octane fuel in their cars, that have engines that use "regular," will make the car go faster and accelerate faster because the engine will make more power with the "high power," high octane fuel. All of your friends will be wrong. Simply putting high octane fuel in your low compression engine that is not designed to use high octane fuel, that does not require the use of high octane fuel to prevent detonation, will not allow the engine to make more power. Apparently, in 1937, this was also a common misconception but, since the 100 octane fuel was just newly available, perhaps this misconception can be forgiven. The power setting table for these engines proves this, using the higher octane 91/96 fuel produces the exact same power output as when using 80/87 octane, the higher octane does not produce more power and the same is true if using 100 octane fuel.

Another question presents itself, where did Earhart get the 100 octane fuel, did she tanker it all the way around the world?

gl

gl
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 07, 2011, 12:48:13 PM
But even if she is misinformed she is making her plans with the information she has. Not the technically accurate information of today but what she was told then. Why else fly around with a tank of 100 octane?  And if it had just been introduced on the market then maybe some slick sales guys made a statement that later turns out to be false but she didn't know that at the time.  Think 1937.  What info she had is what she made decisions on.
Title: Re: Octane Analysis
Post by: Richard C Cooke on December 07, 2011, 01:35:35 PM
But even if she is misinformed she is making her plans with the information she has. Not the technically accurate information of today but what she was told then. Why else fly around with a tank of 100 octane?  And if it had just been introduced on the market then maybe some slick sales guys made a statement that later turns out to be false but she didn't know that at the time.  Think 1937.  What info she had is what she made decisions on.
She should have had a pilots operating manual that should have said what to do when you have to take off with low octane fuel.  Most that I have seen give an alternate take off boost and rpm setting.

Richard Cooke
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 07, 2011, 02:07:11 PM
I think that has been covered previously in this thread. See Jeff Neville reply #9 for info.  The choice is still AE's as to what octane and power settings to use to take off from Lae with a full load of fuel.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 07, 2011, 07:11:05 PM
But even if she is misinformed she is making her plans with the information she has. Not the technically accurate information of today but what she was told then. Why else fly around with a tank of 100 octane?  And if it had just been introduced on the market then maybe some slick sales guys made a statement that later turns out to be false but she didn't know that at the time.  Think 1937.  What info she had is what she made decisions on.
She should have had a pilots operating manual that should have said what to do when you have to take off with low octane fuel.  Most that I have seen give an alternate take off boost and rpm setting.

Richard Cooke
-----
Sure, see the attached power setting table from Pratt & Whitney. It says when using normal (not low octane) 81/87 octane fuel, the power settings to get the full 600 hp are 2250 rpm and 35.5 inches of manifold pressure. When using higher octane 91/96 fuel, to get the SAME 600 hp you must use 2250 rpm and a higher 36.0  inches of manifold pressure.

https://tighar.org/smf/index.php?action=dlattach;topic=528.0;attach=404

gl
Title: Re: Octane Analysis
Post by: Richard C Cooke on December 07, 2011, 08:35:57 PM

https://tighar.org/smf/index.php?action=dlattach;topic=528.0;attach=404

gl
The date it was issued, so we can be sure this was the information available to AE.

RC
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 07, 2011, 09:05:58 PM
Also Gary, AE wasn't big on learning about her aircraft. Why would she open or use manuals?  If everyone knew 100 octane was a waste of time then why did she have it in her aircraft and ferry it around?  It's what she believed that matters. She planned things based on the knowledge she knew. Even if it's wrong its what she believed was right. Her reality. Her opinion.  Her plan.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 07, 2011, 09:48:25 PM
Also Gary, AE wasn't big on learning about her aircraft. Why would she open or use manuals?  If everyone knew 100 octane was a waste of time then why did she have it in her aircraft and ferry it around?  It's what she believed that matters. She planned things based on the knowledge she knew. Even if it's wrong its what she believed was right. Her reality. Her opinion.  Her plan.
As I wrote a week ago:

"That is my point and the extra hour of flight endurance could have allowed Earhart to find Howland, or some other island or, if she landed on Nikumororo then the extra fuel would have provided many hours of extra radio transmitting time, take your pick."

Of course she made decisions based upon the information she had at the time, it is just unfortunate that she was misinformed.

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on December 07, 2011, 09:59:19 PM

The issue that we were initially discussing was the question:  IF the 81 gallon tank that contained about 40.5 gallons of 100 octane fuel had been "topped off" with 40.5 gallons of 80/87 octane fuel, THEN would the distance to takeoff have been appreciably lengthened?
I guess you missed this, I put it on a different thread:

----------------------------------------------------

"What Johnson said was correct for a 14,000 pound takeoff without flaps but was definitely NOT TRUE for a 15,000 pound takeoff which takes significantly more than 2,000 feet at standard conditions and even more at the 2,000 foot density altitude at Lae. According to report 487, it takes 2,600 feet to take off without flaps at 16,500 pounds at a sea level density altitude. Doing the same calculations we did before, we find that a takeoff at Lae at a density altitude of 2,000 feet and 15,000 pounds without flaps results in a ground run of 2,278 feet. Lest you think that this is all just theoretical mumbo-jumbo, this calculation agrees quite closely with Chatter's observation of 2,550 feet, a difference of only 272 feet, less than a 12% difference thus Chatter's observation confirms the accuracy of this calculation. (I accept Chatter's report as more accurate in all of it's detail compared to Collopy's short letter.)

It is interesting to look at what would have happened if Earhart had completely filled that tank, adding about 50 U.S. gallons weighing 300 pounds. A takeoff at 15,300 pounds without flaps would have taken 2,370 feet, only 92 feet longer. And if she had put the flaps down to the 30° position specified in report 487 the takeoff would have taken only 1,914 feet providing a 1,086 foot safety margin, 57% extra runway.

We know that Earhart did not fill that tank because she believed that she needed 100 octane fuel to get maximum power out of her engines but Pratt and Whitney documents show that the engines make full takeoff power of 600 horsepower using the 87 octane fuel available at Lae (Jeff Neville disputes this) so she could have filled that tank, made a safe takeoff, and then have an extra hour of flying endurance to find a safe place to land.

Just for the sake of argument, let's say that Neville is correct and that she could only get 550 horsepower from each engine using 87 octane fuel, how would this have affected the takeoff? The length of the takeoff run varies with the inverse of the ratio of the engine power. Report 487 shows 2,100 feet for standard conditions, 30° of flaps, and 16,500 pounds using the full power of 600 horsepower from each engine, a total of 1,200 horsepower so taking off with a total of 1,100 hp gives a takeoff distance 9% longer, 2,290 feet. We adjust this for the takeoff weight of 15,300 pounds as we did before and find 1,970 feet. We then increase this by 6% to account for the density altitude so the complete calculation gives 2,088 feet compared to 1,914 for 1,200 hp (we could have just multiplied the 1,914 by 1.09 too), only 174 feet longer and with 912 foot safety margin, 44% extra runway available. Doing the same calculation for the flaps up scenario produces a takeoff run of 2,585 but this would be cutting it close so Earhart would have to have remembered to set the flaps correctly.
So no matter how you figure it, Earhart unnecessarily left behind an hour's worth of fuel and this fuel could have made a significant difference in the end. "
----------------------------------------------------

gl
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 07, 2011, 11:26:09 PM
But your calculations are all based on what she needed to take off from Lae.  I believe she was thinking ahead to the takeoff at Howland. She really didn't know much about what was going on there as she wasn't doing a lot of talking with Itasca. Is there a record of her asking what shape the new unpaved strip was in?  Yes Gary many people in Washington were concerned that she get a good runway but they were in Washington. Not on the actual island. Why the incessant commentary on leaving without mixing the 100 octane she thought could boost her take off. A little insurance ( she believed) for that unknown runway.  Mixing her octanes for 50 more gallons when she calculated an ample reserve just seems like throwing her insurance away. Anyway she didn't do it so I must be right. LOL.
Title: Re: Octane Analysis
Post by: JNev on December 08, 2011, 01:05:43 PM
If AE was flying with one tank of 100 octane because she had been told or led to believe she needed it for extra power on takeoff then why would she have that tank topped up with non 100 octane. She believed she had plenty of fuel, with ample reserve, for the trip to Howland.
She did know that Howland's airstrip had just been constructed and has no idea what shape it was really in. So saving any 100 octane for a "boosted" takeoff on a new runway on a small island would have been prudent.
EXCELLENT - YOU GET IT, Irvine John Donald; THE HIGHEST MP SETTINGS BY WHICH TO OBTAIN MAX HP IS PRECISELY THE POINT; IT'S NOT JUST ABOUT 'MAX POWER' IN THE LOOSE TERMS OF '600 HP' WE'VE SEEN REPEATEDLY PLASTERED HERE. - Jeff
She didn't plan on getting lost and needing every tank to be 100% full.  But she did need to plan her takeoff from Howland. If some of the arguments/inferences in this thread are true then why was she carrying two types of octane in the first place?
I THINK YOU NAILED THE POINT - THERE WAS GOOD REASON FOR HER TO PRESERVE THE 100 OCTANE STASH - Jeff
...High octane fuel is needed in high compression engines to prevent detonation (knock) that can quickly damage the engine. Earhart's S3H1 engines are low compression engines with a compression ratio of only 6:1, designed to make full takeoff power with the 87 octane fuel available at Lae...
ALL TRUE - PROVIDED ONE DID NOT EXCEED THE CRITERIA WE'VE BEEN TALKING ABOUT (INCLUDING MP) - Jeff
One hundred octane fuel only became available, in experimental quantities, in 1934. The S3H1 had been designed to use the existing 87 octane fuel because it takes a lot longer than the one or two years that 100 octane fuel was available, prior to the actual construction of her engines, to design a new aircraft engine.
VERY GOOD FIND, GARY; YES - EXCEPT FOR THE NEED IN THE CONDITIONS PREVIOUSLY NOTED (WHICH YOU TEND TO CONTINUE TO IGNORE), AND THAT BY WHATEVER MEANS, AE DID HAVE 100 OCTANE IN A TANK - Jeff
Only one of the 107 other versions of the Wasp engine, many designed during WW2 after 100 octane fuel was freely available, required the use of 100 octane fuel and even that one version only put out 600 hp, just like Earhart's engines. (That one engine type was fuel injected and had many other modifications.) Think about it, there was a lot of pressure and incentive for Pratt & Whitney to increase the power of these engines, ("don't you know, there's a war on") but they were unable to do so even when 100 octane and other even higher octane fuels were available, all the way up to 145 octane.
INTERESTING - BUT NOT COMPLETELY ACCURATE PER THE LONG-FETED TCDS FOR THE , UNDER CERTAIN CONDITIONS, AGAIN CONSIDERING MP, ETC. - Jeff
Ask all of your friends and I bet that they will all say the same thing, that putting high octane fuel in their cars, that have engines that use "regular," will make the car go faster and accelerate faster because the engine will make more power with the "high power," high octane fuel. All of your friends will be wrong.
WITH EXCEPTION OF HAVING SO MANY FRIENDS WHO WOULD BELIEVE IT (WORD ABOUT THAT MYTH HAS GOTTEN ABOUT), THAT IT IS A GOOD POINT, AND TRUE - Jeff
Simply putting high octane fuel in your low compression engine that is not designed to use high octane fuel, that does not require the use of high octane fuel to prevent detonation, will not allow the engine to make more power. Apparently, in 1937, this was also a common misconception but, since the 100 octane fuel was just newly available, perhaps this misconception can be forgiven. The power setting table for these engines proves this, using the higher octane 91/96 fuel produces the exact same power output as when using 80/87 octane, the higher octane does not produce more power and the same is true if using 100 octane fuel.
IT IS DOUBTFUL THAT AE BOTHERED WITH THE 100 OCTANE RESERVE OUT OF MYTH; IT IS PROBABLE THAT IT WAS ABOARD FOR THE REASONS WELL UNDERSTOOD - MAX USE OF MP TO ENSURE MAX POWER ON TAKE-OFF AND INITIAL CLIMB WITH LESS RISK OF DETONATION/PRE-IGNITION; IT MAY WELL HAVE BEEN A 'CONSERVATIVE' DECISION, TOO - AS YOU'VE NOTED, LESS WAS UNDERSTOOD IN THOSE TENDER YEARS OF FUEL AND POWER DEVELOPMENT. - Jeff
Another question presents itself, where did Earhart get the 100 octane fuel, did she tanker it all the way around the world?
NOT SURE WE KNOW - PERHAPS SHE ONLY HAD USED AROUND 50 GALLONS BY THE TIME SHE WAS READY TO TAKE-OFF FROM LAE, SO MAYBE IT WAS WHAT WAS LEFT FROM TAKE-OFF AT MIAMI (I HAVE NOT DONE THE MATH, BUT YOU CAN IF YOU LIKE: LOOK AT THE TIME LIMITS / LIKELY MAX CONSUMPTION PER TAKE-OFF X NUMBER OF TAKE-OFFS TO THAT POINT).  ONE THING SEEMS CLEAR - THERE WASN'T ANY AT LAE. - Jeff
gl

gl

Some of this was interesting as a 'continuance', so I made a few comments in bold italics throughout...

LTM -
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 08, 2011, 01:32:12 PM
Hi Jeff. Yes I think Gary made some good points on the fact that 100 octane doesn't "boost" anything. And my point to him is that it doesn't matter what we believe or can prove, it's what did AE believe.

We see this often in current marketing practices where a claim is made to market a product and the claim is later found to be incorrect. (Boy I had to dance around that statement.).
If AE bought into the claims on this new higher octane performance then it "may" explain why she had it on the flight.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 08, 2011, 09:15:37 PM
I can see that and agree - and I still think she had valid reasons for it -

While NR16020's Wasps were indeed 'low compression' as has been pointed out by Gary, they were also 'boosted' by a supercharger.  I'm not sure I can reliably remember the impeller gear ratio but believe it was 10:1 on the TCDS (ratio is neither here nor there for our purposes, just one item on the sheet that affirms a blower was present) -

That's how one would get the 36.5" of manifold pressure cited in the TCDS - when the higher octane fuel happens to be indicated.  It is curious that this point never got mentioned in this whole string - it is almost as if the presumption all along was that these were naturally aspirated engines.  If they had been naturally aspirated we wouldn't be having the discussion on octane and effects and AE's necessities on this point - yhe higher octane consideration would not be in the picture.  'Blown' engines poke more air mass into the combustion chambers - and have a similar effect at higher MPs that a 'higher compression ratio' would naturally have (it is all about relative mass and relative compression values).

A naturally aspirated engine would only develop around 28.5" or so of MP max on a fair day - something just under ambient barometric pressure (there is a pressure drop over the throttle plate, etc.).  In that case you could knock yourself out all day with a Wasp and never get close to ill effects.

If memory serves, you don't start creeping over the line in a naturally aspirated engine to a need for higher octane ratings until past around 8.5:1 compression or so.  From boyhood on the flight line, I recall Cherokee 140's having a basic requirement for 80 octane fuel - their O-320 engines probably had 6:1 or so compression ratios; the Cherokee 180 was different - 91/97 octane for their O-360 engines that were likely more like 8:1 or something higher (I haven't looked it up - someone can for the exercise if they wish to).  As a practical matter, our little airport stocked (in those days) "80" and "100" (really 80/87 and 100/115), so 140's got "80" and 180s got "100" octane at the pump.

How can I remember thatso well?  Guess which 14 year-old line boy (at the time) topped off a 180 one night with 80 octane... I thought I had ruined the airplane.  The wonderful fellow who ran the place listened to my confession and then gave me one of my earliest technical short-courses in aviation: why different airplanes required different grades (compression ratios, volatility, etc.) - and that the amount of 80 octane I had pumped into the 180 was not enough to dilute the existing 100 octane below any safe level.  The man was not only an experienced civilian aviator of great talent and learning, he was a retired naval aviator with many years of training and experience with large recips.

So in fact, and very close to one part of Gary's insistence with which I never disagreed, the Wasp was quite tolerant up to a fair degree of boost: it is only at the very highest MP's where the higher octane is required (...where the 'anti-knock' solution becomes more critical).

And I should proabably just leave it all with your own elegant take-away - it is what AE actually did that counts, and her reasons would be easy enough to understand.

So, forgive my ruminations - but AE proabably did have a fair understanding that one just doesn't slam the shiney things forward to the wall on a boosted engine without knowing they're not going to trigger destructive problems.  100 octane would be one easy way to ensure that wouldn't happen, and I suspect she still had the remnants of the original stash aboard, possibly from Miami, for another take-off at Howland, after Lae.  Makes sense.

LTM -
I'll leave you with just one word, PLANK.  ;)

gl
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 08, 2011, 09:45:33 PM

Makes sense?
Let's see, am I to understand that AE loaded up a tank with 81 gallons of 100 octane gas (486 lbs) and schlepped it half way around the world because she might need it for takeoff from Howland?  I think not!

If she felt that she needed that flavor of gas at Howland, George Putnam would have assured that 2 druns (110 gallons), at least, would have been included in the fuel cache waiting for her at Howland.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 09, 2011, 03:58:25 AM
If AE was flying with one tank of 100 octane because she had been told or led to believe she needed it for extra power on takeoff then why would she have that tank topped up with non 100 octane. She believed she had plenty of fuel, with ample reserve, for the trip to Howland.
She did know that Howland's airstrip had just been constructed and has no idea what shape it was really in. So saving any 100 octane for a "boosted" takeoff on a new runway on a small island would have been prudent. She didn't plan on getting lost and needing every tank to be 100% full.  But she did need to plan her takeoff from Howland. If some of the arguments/inferences in this thread are true then why was she carrying two types of octane in the first place?
Except we know that they had planned to carry only 825 gallons of fuel for the leg from Howland to Hawaii which is only 1892 SM, 664 SM shorter than the Lae to Howland leg. This is 275 gallons less than they carried on takeoff from Lae so the weight of the plane would have 1650 pounds less, only about 13,350 pounds. Doing the same takeoff calculations I have shown before we know that the takeoff distance varies with the weight ratio squared. Report 487 gives 2100 feet for a takeoff at 16,500 pounds, 13,350 pounds is only 0.809 of the maximum weight, which squared equals 0.654 times 2100 feet predicts the takeoff distance at Howland of 1,375 with 30° of flaps. For a no flap takeoff the distance would be the same 0.654 times 2,600 feet for a Howland takeoff distance of 1,700 feet.

We also have confirmation that these calculation are accurate. The plane weighed 14,000 pounds on takeoff from Oakland and that takeoff was without flaps. Doing the same calculation, the formula predicts the takeoff distance at Oakland  of 1872 feet. The actual measured distance for that takeoff was 1897 feet, a difference of only 25 feet! Even if Earhart didn't want to do this calculation she knew from the Oakland takeoff that she could takeoff in only 1897 feet at a weight of 14,000 pounds and she knew that she would weigh less than that at Howland so would know that she could get off in the same 1897 feet without flaps and even shorter if she chose to use flaps.

Based on this, there was a large safety margin at Howland so no reason to worry about a takeoff even with less than full power if she believed that she couldn't get full power if only 87 octane was provided by the Coast Guard. It is also certainly possible that Earhart had a barrel of 100 octane landed at Howland.

gl

gl
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 09, 2011, 05:39:38 AM
No Harry. She didn't truck it around the world just for Howland. The question everyone was asking is why she didn't fill that tank before leaving Lae. I simply raise a possibility.

Gary you have an excellent technical answer for why she didn't need the 100 octane. Now please give me an excellent technical answer for A) why she had it in the first place and B) why she didn't fill that tank with 87 octane and have a blend.

If AE had all of this knowledge that said she didn't need 100 octane then why did she have it???

Come on guys. It's 1937. World war 1 ended only 19 years before. All of the many advances of ww 2 have not yet taken place. So the science of flying isn't nearly as advanced as today. It's barely out of barnstorming.  This is a woman out to make a name for herself who doesn't even know morse code or have a morse key with her or have proper communication plans with the one CG ship she should absolutely be in touch with.  Her communications and overall planning were lacking but you want me to believe that in the area of fuel and engines she knew then what you know today?

Try getting into her head and say WHY she carried the fuel. Not why she didn't need it. I look forward to the answer.
Title: Re: Octane Analysis
Post by: John Ousterhout on December 09, 2011, 08:15:49 AM
How many of us have gotten a tank full of "bad" fuel, even at modern airports?  As IJD says, "It's 1937... ", and fuel quality in foreign lands may have been highly variable.  If it were me, I'd want at least one tank of uncontaminated fuel.  She wasn't going to know how each fillup would perform as she progressed on her flight until she switched tanks. Since takeoff is the most unforgiving time in each leg, when an engine hiccup is intollerable, so she might have simply wanted a guaranteed tank of trouble-free fuel, and 100-octane is sort of a "belts and suspenders" approach.

She may have known that 87 octane gave her full power, but worried that a tank full of bad fuel that was only ~60 octane would be dangerous.

Where was her last opportunity to fill the tank with 100 octane and verify "good fuel" with a low-weight takeoff on a long field - maybe Darwin?

How many gallons would she burn in a heavy takeoff and initial climbout at max power?
Title: Re: Octane Analysis
Post by: Gary LaPook on December 09, 2011, 10:31:59 AM
No Harry. She didn't truck it around the world just for Howland. The question everyone was asking is why she didn't fill that tank before leaving Lae. I simply raise a possibility.

Gary you have an excellent technical answer for why she didn't need the 100 octane. Now please give me an excellent technical answer for A) why she had it in the first place and B) why she didn't fill that tank with 87 octane and have a blend.

If AE had all of this knowledge that said she didn't need 100 octane then why did she have it???

Come on guys. It's 1937. World war 1 ended only 19 years before. All of the many advances of ww 2 have not yet taken place. So the science of flying isn't nearly as advanced as today. It's barely out of barnstorming.  This is a woman out to make a name for herself who doesn't even know morse code or have a morse key with her or have proper communication plans with the one CG ship she should absolutely be in touch with.  Her communications and overall planning were lacking but you want me to believe that in the area of fuel and engines she knew then what you know today?

Try getting into her head and say WHY she carried the fuel. Not why she didn't need it. I look forward to the answer.
I've said it several times, she was misinformed about the capabilities of higher octane fuel as are almost all people, even today.

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on December 09, 2011, 10:34:58 AM
How many of us have gotten a tank full of "bad" fuel, even at modern airports?  As IJD says, "It's 1937... ", and fuel quality in foreign lands may have been highly variable.  If it were me, I'd want at least one tank of uncontaminated fuel.  She wasn't going to know how each fillup would perform as she progressed on her flight until she switched tanks. Since takeoff is the most unforgiving time in each leg, when an engine hiccup is intollerable, so she might have simply wanted a guaranteed tank of trouble-free fuel, and 100-octane is sort of a "belts and suspenders" approach.

She may have known that 87 octane gave her full power, but worried that a tank full of bad fuel that was only ~60 octane would be dangerous.

Where was her last opportunity to fill the tank with 100 octane and verify "good fuel" with a low-weight takeoff on a long field - maybe Darwin?

How many gallons would she burn in a heavy takeoff and initial climbout at max power?
But how would she be certain of the quality of 100 octane fuel purchased somewhere along her route? It would be just as likely to be contaminated as the normal 87 octane fuel bought along the way.

gl
Title: Re: Octane Analysis
Post by: JNev on December 09, 2011, 11:21:05 AM
From the "Chater Report (http://tighar.org/Projects/Earhart/Archives/Documents/Chater_Report.html)" -

"July 1st — after the machine was tested the Vacuum Oil Co.’s representatives filled all tanks in the machine with 87 octane fuel with the exception of one 81 gallon tank which already contained 100 octane for taking off purposes. This tank was approximately half full and it can be safely estimated that on leaving Lae the tank at least 40 gallons of 100 octane fuel – (100 octane fuel is not obtainable in Lae)."

By Chater's report, this is what "AE did", and thereby Chater has stated "the reason for it".  I find no good reason to question this.  It also just happens to be consistent with an L10E "book" take-off at 36.5" MP boosted / 2300 rpm / 600 at sea level for 1 minute from Lae.  That's fits the criteria as published today; apparently the same was understood at that time.

In the Report of the Tenth Cruise to the American Equatorial Islands (http://tighar.org/Projects/Earhart/Archives/Documents/Reports/BlackCruise.pdf), Richard Black reported:

"Four drums (200 gallons) of 100 octane gasoline (special for take-off) and numerous spare parts, supplies, and tools are being carried to (H)howland for the Earhart flight."

It is interesting what history can tell us.

---

Quote from Gary LaPook -

Quote
I've said it several times, she was misinformed about the capabilities of higher octane fuel as are almost all people, even today.

gl

That's your judgment; if so, then so must have been everyone else around her - like Kelly (Lockheed), Mantz, Marshall (P&W), and in other ways, Noonan, Hooven, etc...  I disagree.

LTM -
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 09, 2011, 11:25:20 AM
No Harry. She didn't truck it around the world just for Howland. The question everyone was asking is why she didn't fill that tank before leaving Lae. I simply raise a possibility.

Gary you have an excellent technical answer for why she didn't need the 100 octane. Now please give me an excellent technical answer for A) why she had it in the first place and B) why she didn't fill that tank with 87 octane and have a blend.

If AE had all of this knowledge that said she didn't need 100 octane then why did she have it???

Come on guys. It's 1937. World war 1 ended only 19 years before. All of the many advances of ww 2 have not yet taken place. So the science of flying isn't nearly as advanced as today. It's barely out of barnstorming.  This is a woman out to make a name for herself who doesn't even know morse code or have a morse key with her or have proper communication plans with the one CG ship she should absolutely be in touch with.  Her communications and overall planning were lacking but you want me to believe that in the area of fuel and engines she knew then what you know today?

Try getting into her head and say WHY she carried the fuel. Not why she didn't need it. I look forward to the answer.
I've said it several times, she was misinformed about the capabilities of higher octane fuel as are almost all people, even today.

gl

Ok Gary. So you understand then why she didn't dilute the 100 octane.  She was misinformed. And that was probably one of the lesser mistakes that led to the tragic end.  Jeff's newest post certainly adds to the story.  Nice detective work Jeff.
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 09, 2011, 11:44:35 AM

My answer is strictly an opinion.
AE, rememberibg her groundloop experience at Hawaii and the misinformation concerning takeoff power and octane, dedicated one 81 gallon tank to 100 octane fuel and filled that tank at each refuelibg point.  Discovering that Lae had no 100 octane gas, she didn't want to dilute what high-test she had.(about 40.5 gallons)

The real question is why, during the extensive planning stage for the World Flight, didn't they discover that Lae didn't have 100 octane?  I'm sure that George Putnam could have arranged to have a few barrels (55 gallons each) at Lae waiting for AE's arrival from Darwin.
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 09, 2011, 01:32:26 PM
My answers are always my opinions too. As far as my wife is concerned I'm not right very often.

You raise a good point Harry. Jeff's post shows more 100 octane being delivered to Howland than she had room for in that 81 gallon tank.  None at Lae but too much at Howland. Poor planning?  Or careful planning by making sure extra was available. (Even though she didn't "need" it. Right Gary?).

Hard to say on that one.
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 09, 2011, 02:11:28 PM

My answer is strictly an opinion.
AE, rememberibg her groundloop experience at Hawaii and the misinformation concerning takeoff power and octane, dedicated one 81 gallon tank to 100 octane fuel and filled that tank at each refuelibg point.  Discovering that Lae had no 100 octane gas, she didn't want to dilute what high-test she had.(about 40.5 gallons)

The real question is why, during the extensive planning stage for the World Flight, didn't they discover that Lae didn't have 100 octane?  I'm sure that George Putnam could have arranged to have a few barrels (55 gallons each) at Lae waiting for AE's arrival from Darwin.

What 'misinformation' about take-off power and octane?  We have no direct evidence that she was so mis-informed that I can see.  We have Gary's opinion that nearly everyone other than him is misinformed - and that of whomever may agree with him (and if that's you, sorry).

Even if AE had been 'misinformed', and thereby had 100 octane aboard 'illadvisedly', what material impact would it have had on ANYTHING to do with any segment of the flight, or with the Luke Field event?  It would be completely benign and would impose no negative effects - excepting the one argument about AE having limited her range by possibly an hour due to a short fuel load at Lae.

I seriously doubt that AE always kept only one 81 gallon tank reserved for 100 octane the whole trip.  The 200 gallons Black was bringing to Howland suggests something: fill a couple of tanks with 100 octane FIRST - top off with 80 in the remaining tanks and thereby assure a running reserve of 100.  That may well have also been done as a reserve tactic prior to Lae for all we can tell at moment; if that's important to someone maybe they can find the records.  It is also clear that AE wanted plenty for the take-off at Howland - which suggests the 40 gallons or so aboard at Lae would have been expected to have been consumed.

Why didn't they know Lae had no 100 octane?  We don't "know" that AE, Putnam & Co. "didn't know": Chater never indicated that as a surprise, just a fact; I can't tell from his statement that Lae never had it, either - maybe not, or maybe just at that time.  That AE still had 40 gallons or so of high octane fuel at Lae is not inconsistent with AE ensuring that she arrived Lae with a supply for the next take-off or so, either.

In any case, the absence of 100 octane at Lae did not create any problems - unless one is critical of AE leaving there with less than a full bag of fuel.  Route distance, etc. can show why they may not have felt they needed the full bag, rationally enough.  Of course we can argue otherwise, endlessly.  Point is that's how they departed there, and their rationale can be understood, whether it is what we'd do or not.

One funny thing about all of this whole discussion - pick apart whatever piece of it one will as ill-advised and tsk-tsk over what one sees as ignorance all one will, but the truth is AE's whole round-robin effort was folly and ill-advised for good reasons anyway - one of which stares back every time we engage in this chase:
It was fraught with unnecessary peril.
Had AE not succombed to that unwarranted peril we would be chasing a different holy grail - and presumably picking it apart, feather-by-feather...

LTM -

Jeff you are absolutely right. It makes no difference to the particulars of her flight.  But after all this time and with TIGHAR's extensive investigation there is still no "conclusive evidence" that the theory is right. So, in my opinion, you need to step back and look at the puzzle from other angles. Gary's skepticism of the theory makes people defend it and I believe the arguments put forth generally strengthen the theory's viability. Just look at your dialogue with Gary over the last few days!  Great stuff from both sides!!  I believe that if this type of back and forth carries on in ALL of the threads in this forum then the theory will continue to strengthen and perhaps even new facts may come to life.  There are many people out there who read these forum topics but don't contribute. They really should. Every new idea, and the regurgitation of the old ones, is important. Even when the threads don't make a big impact on material fact. Like the topic of this one. "Octane Analysis".  If it makes people think then it's worthwhile.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 09, 2011, 06:22:21 PM
From the "Chater Report (http://tighar.org/Projects/Earhart/Archives/Documents/Chater_Report.html)" -

"July 1st — after the machine was tested the Vacuum Oil Co.’s representatives filled all tanks in the machine with 87 octane fuel with the exception of one 81 gallon tank which already contained 100 octane for taking off purposes. This tank was approximately half full and it can be safely estimated that on leaving Lae the tank at least 40 gallons of 100 octane fuel – (100 octane fuel is not obtainable in Lae)."

By Chater's report, this is what "AE did", and thereby Chater has stated "the reason for it".  I find no good reason to question this.  It also just happens to be consistent with an L10E "book" take-off at 36.5" MP boosted / 2300 rpm / 600 at sea level for 1 minute from Lae.  That's fits the criteria as published today; apparently the same was understood at that time.

In the Report of the Tenth Cruise to the American Equatorial Islands (http://tighar.org/Projects/Earhart/Archives/Documents/Reports/BlackCruise.pdf), Richard Black reported:

"Four drums (200 gallons) of 100 octane gasoline (special for take-off) and numerous spare parts, supplies, and tools are being carried to (H)howland for the Earhart flight."

It is interesting what history can tell us.

---

Quote from Gary LaPook -

"I've said it several times, she was misinformed about the capabilities of higher octane fuel as are almost all people, even today.

gl"

That's your judgment; apparently then so must have been everyone else around her, Gary.  Too bad she didn't have you for an advisor to overcome the ignorance of others, like Kelly (Lockheed), Mantz, Noonan, Marshall (P&W), Hooven...  I disagree for more objective reasons than your judgment.

LTM -
Jeff,
"PLANK... service."

In my prior post I wrote, "I'll leave you with just one word, PLANK.  ;)," I was just being humorous and I fully expected that you would recognize the standard aircraft engine thermodynamic formula for computing horsepower by the use of "PLANK." Since you didn't even recognize this standard formula, I now take it that you never learned how to compute horsepower and this probably  explains your misunderstanding of the power settings contained in the P&W TCDS E-143 and in the P&W power setting table for the S3H1 engine. I thought that this formula was taught to all A&Ps (you are an Airplane and Powerplant Mechanic, right) so did you miss class that day, or what?
I have attached the FAA test questions for the A&P General Exam, try questions 34, 36, 37, 38, 44 and 57 as a review.
As long as we are at it Jeff, since you also post about Noonan's navigation, I have attached the FAA Flight Navigator test questions, let me know how you do on them.

gl
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 10, 2011, 12:00:17 PM

Three Things
1. Ric said in a post somewhere on the forum that drums of fuel with AE's name on them were pre-positioned at fueling points.
2. Chater said that an 81 gallon tank was half full of 100 octane fuel but wasn't filled because there was no 100 octane at Lae.
3.  Black said that there was 200 gallons of 100 octane (for takeoff purposes) was on board the ship to Howland.

My guess is that AE took off from Darwin with a full 81 gallon tank of 100 octane anticipating the use of about half (40 gallons) at takeoff from Darwin and half at takeoff from Lae, then refueling the tank at Howland.  This would explain why they didn't assure a supply of 100 octane at Lae.
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 10, 2011, 12:06:43 PM
It does seem like value has been credited towards 100 octane fuel as being necessary based on Harry's summary.  And by lots of knowledgable people. But even still the 100 octane coesnt really advance the theory. It has little impact. IMHO
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 10, 2011, 12:50:00 PM

I wasn't aware that we  were attempting to "advance a theory".  I thought we were testing an hypothesis against known facts and conclusions in order to explain what happened, why/how it happened and what can/should be done to prevent it from happening again.

I suggest the reading of a book entitled "Destination Disaster "(subtitled Ford Trimotor to DC-10) by Paul Eddy, Elaine Potter, and Bruce Page as an example of how an Accident/Incident (A/I) Investigation takes place and where the various threads lead.  Note especially the FAA's fix to an A/I that killed nearly 400 people.
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 10, 2011, 04:01:41 PM

The primary cause of the 1974 DC-10 crash was a failure of the baggage door locking mechanism, resulting in a collapse of the passenger compartment floor and the shearing off of the control cables.  The FAA's fix was to require that a sign be posted near the door instructing the gorilla/baggage handler to look and be sure the door is closed and locked.  The message was in English, the handler was Turkish.
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 10, 2011, 10:13:45 PM

I wasn't aware that we  were attempting to "advance a theory".  I thought we were testing an hypothesis against known facts and conclusions in order to explain what happened, why/how it happened and what can/should be done to prevent it from happening again.

I suggest the reading of a book entitled "Destination Disaster "(subtitled Ford Trimotor to DC-10) by Paul Eddy, Elaine Potter, and Bruce Page as an example of how an Accident/Incident (A/I) Investigation takes place and where the various threads lead.  Note especially the FAA's fix to an A/I that killed nearly 400 people.

I have spent some time this evening reviewing the definitions of "theory" and "hypothesis".  It's clear there is a distinct difference between these two terms. You are correct Harry. My use of the phrase "advancing a theory" was incorrect. TIGHAR is testing a hypothesis and I apologize for my indiscretion. My phrase misrepresents TIGHAR's work.

A theory is an explanation. A hypothesis is a testable idea.  You do not set out to prove a hypothesis, simply test it.  I wonder if Ric and other senior members could give us some insight into why they chose hypothesis over theory.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 11, 2011, 01:36:46 AM

I wasn't aware that we  were attempting to "advance a theory".  I thought we were testing an hypothesis against known facts and conclusions in order to explain what happened, why/how it happened and what can/should be done to prevent it from happening again.

I suggest the reading of a book entitled "Destination Disaster "(subtitled Ford Trimotor to DC-10) by Paul Eddy, Elaine Potter, and Bruce Page as an example of how an Accident/Incident (A/I) Investigation takes place and where the various threads lead.  Note especially the FAA's fix to an A/I that killed nearly 400 people.

I have spent some time this evening reviewing the definitions of "theory" and "hypothesis".  It's clear there is a distinct difference between these two terms. You are correct Harry. My use of the phrase "advancing a theory" was incorrect. TIGHAR is testing a hypothesis and I apologize for my indiscretion. My phrase misrepresents TIGHAR's work.

A theory is an explanation. A hypothesis is a testable idea.  You do not set out to prove a hypothesis, simply test it.  I wonder if Ric and other senior members could give us some insight into why they chose hypothesis over theory.
Right, and when you are confronted with evidence that conflicts with your hypothesis you re-evaluate your hypothesis, you don't just try to discredit and explain away and avoid the conflicting evidence.

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on December 11, 2011, 01:46:46 AM

The primary cause of the 1974 DC-10 crash was a failure of the baggage door locking mechanism, resulting in a collapse of the passenger compartment floor and the shearing off of the control cables.  The FAA's fix was to require that a sign be posted near the door instructing the gorilla/baggage handler to look and be sure the door is closed and locked.  The message was in English, the handler was Turkish.
Yep, but it apparently worked, we haven't had a repeat of that accident. Here is a different DC-10 accident that I litigated.

http://dms.ntsb.gov/aviation/AccidentReports/k2yqxd455dcfn355i2k533551/U12112011120000.pdf

gl

gl
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 11, 2011, 11:20:51 AM

Sary
No, it didn't work.
Prior to the Turkish Airways fatal crash in France with the DC-10 baggage door there had been an identical incident in the US which, because of the pilot's self-training and ability to fly the DC-10 without control of the control  surfaces, was survivable and without casualities.  He landed the plane safely using only the three engines.

That's when the FAA did the sign posting solution.  Not FIX THE DOOR LOCKING MECHANISM but put up a sign.  The Turkish plane had the sign, the gorilla/baggage handler couldn't read english   OOPS. 386 people perished.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 11, 2011, 04:03:34 PM

Sary
No, it didn't work.
Prior to the Turkish Airways fatal crash in France with the DC-10 baggage door there had been an identical incident in the US which, because of the pilot's self-training and ability to fly the DC-10 without control of the control  surfaces, was survivable and without casualities.  He landed the plane safely using only the three engines.

That's when the FAA did the sign posting solution.  Not FIX THE DOOR LOCKING MECHANISM but put up a sign.  The Turkish plane had the sign, the gorilla/baggage handler couldn't read english   OOPS. 386 people perished.
I didn't search for accidents prior to the Turkish one. So there have been no similar accidents after the Turkish one which is why I said it worked.

gl

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on December 11, 2011, 04:12:46 PM
It does seem like value has been credited towards 100 octane fuel as being necessary based on Harry's summary.  And by lots of knowledgable people. But even still the 100 octane coesnt really advance the theory. It has little impact. IMHO
The only point I was making is that having an additional hour of fuel on board might have made a difference in the outcome. I have proved that the plane would have taken off safely from Lae with only 550 hp from each engine which was certainly available with 87 octane fuel. (Actually P&W documents show that they could put out the full 600 hp with 87 octane but no reason to go through that battle again since no one yet (are you listening Jeff) is disputing the 550 hp with 87 octane.) So it turns out that there was no good reason to leave with less than full fuel and that might have made a big difference.

gl
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 11, 2011, 04:55:41 PM
But the TIGHAR hypothesis is that they landed on Gardner with fuel on board. IF they had filled that last tank at Lae, wouldn't this just mean they would have had more fuel in the tank when they landed?  It's not like AE flew around until her tanks went empty then crashed into the sea. The post loss radio messages say otherwise.
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 11, 2011, 05:33:11 PM

Irvine
Had they had the additional 40 gallons on board when they landed at Gardiner then , for only one engine at battery charging rpms, it would have represented perhaps 5 hours of additional radio time.  Provided of course that the plane didn't get washed into the sea before then.

As I said before, Gas left behind on a truck at the airfield is of absolutely no use whatsoever and ya never know when ya might need it.
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 11, 2011, 05:54:45 PM
Hi Harry.

I have seen that phrase from several people in these forums. Would you say this is a common practice to always fill every tank at every opportunity?  Is it an old practice going back to the 30's as such?  Would she have been asked at Lae if she wanted the 100 octane tank topped up and refused?  I ask because I believe that there is a reason she didn't fill it.

I agree with everyone that having the extra fuel would be smart.  Your point of being able to run the engine for extra radio time is a very valid. But when someone doesn't do the expected or the norm it makes me question why they did that. Or was the norm of the day to believe that 100 octane would boost take off power.  There is a reason she did what did. Poor judgement, mis informed, maybe nobody bothered to fill that tank?  What's the likeliest reason? Does it effect the hypothesis?
Title: Re: Octane Analysis
Post by: Harry Howe, Jr. on December 11, 2011, 06:27:35 PM
AE had no idea whether she would need those 40 gallons, she had no idea that she would be on an island radioing for help,  athat's my point.  Ya never know when ya might need it, so take it along just in case.

I don't know what was common practice in the '30's or even in the 70's when I was first flying.  I only know what my instructor taught me, it made sense to me, and it became a habit and part of my pre-flight practice when preparing for a cross-country.

I also got into the habit of performing a complete walk around pre-flight of the plane prior to taxi, regardless of how long or how little time I was away from the plane.  Habit.
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 11, 2011, 06:44:40 PM
Seems AE should have had your instructor.  I have several boater friends who enjoy the northern parts of the great lakes. It's common for them to top up whenever they can too. You just never know when you need that little extra mileage.  So I am leaning towards AE being too nonchalant in her planning. Even if she believed the notion that 100 octane helped boost take offs or not, she should have made sure she had 100 octane available for top up at every stop. As Jeff Neville points out, she had 200 gallons being delivered by Itasca for top up at Howland. Ric reminds us that she had fuel propositioned in drums at her stops. Why not a 100 octane top up at Lae regardless of the reason she was carrying it?  You're right Harry. Seems like perhaps she just didn't have the habit.
Title: Re: Octane Analysis
Post by: Gary LaPook on December 11, 2011, 10:31:38 PM
Hi Harry.

I have seen that phrase from several people in these forums. Would you say this is a common practice to always fill every tank at every opportunity?  Is it an old practice going back to the 30's as such?  e hypothesis?
Running out of fuel in flight is a bigger deal than running out while driving your car. Because of this, pilots are trained to be conservative about their fuel supply. There is another reason to fill the tanks up that Harry hasn't mentioned. Fuel gauges in airplanes are notoriously inaccurate today and they were no better 74 years ago. The only way you can be certain of how much fuel you have is when the tanks are full. Federal regulations (posted below) requires that the fuel gauge only be accurate at one point, it must read "zero"at the level of "unusable fuel" which is fuel remaining in the tanks that might not be usable in extreme flight attitudes. Most of the time you can use the "unusable fuel" in normal flight attitudes. Another way to look at the regulation is that the engine can not run out of fuel prior to the gauge indicating "zero" but the engine may continue to run after that point in normal flight attitudes
Some aircraft fuel gauges are marked simply "0" which also has a  "RED LINE"; 1/4; 1/2; 3/4 and "F". Others have markings in gallons. Pilots know to take these markings with a grain of salt since there is no regulation setting out a required accuracy for these marks, except for the RED LINE, and they are not very accurate.

It is difficult to make accurate fuel gauges for airplanes due to the shape of the fuel tanks in the wings, they are long and wide but very shallow, limited by the thickness of the wing. This means that the float on the sending unit has a very limited range of movement that is picked off by a rheostat which is coarse and the wiper may stick between windings. Also, most wings have dihedral meaning that the wing tips are above the wing roots making accurate readout of the fuel even more difficult. In turbulence and when the airplane is maneuvering the fuel can slosh back and forth in the long shallow tanks making the fuel gauges move up and down as the fuel moves around.

Pilots know that they can't rely on their fuel gauges so the most accurate and reliable way to determine the fuel on board is to fill up the fuel tank. Unless there is a major concern with exceeding the maximum gross weight limit, pilots will fill their tanks completely before takeoff. Because of the many separate fuel tanks in the fuselage Earhart could be very confident with their knowledge of the fuel remaining as each tank was drained one by one. After all the fuselage fuel was consumed they only had the inaccurate fuel gauges to rely on in measuring the fuel remaining in the wing tanks.

Since pilots can't rely on their fuel gauges they rely on their clocks. The operating manual tells you what your rate of consumption is at various power setting and altitudes and you divide the amount of fuel in the full tank by the rate of consumption to compute your endurance. If you have multiple tanks you can time how long each lasts and compute your actual rate of consumption which should be a bit more accurate than relying on the aircraft manual and I would expect that Earhart or Noonan did this as each of the fuselage tanks were emptied. But this consumption rate is only valid if the power setting and altitude and temperature remain constant and it is likely that Earhart reduced power as the plane got lighter so their calculated fuel consumption rate could have been inaccurate towards the end.
------------------------------------------
Federal Aviation Regulations, 14 CFR -

§ 23.1553 Fuel quantity indicator.

A red radial line must be marked on each indicator at the calibrated zero reading, as specified in §23.1337(b)(1).

§ 23.1337 Powerplant instruments installation.
......

(b) Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used. In addition:

(1) Each fuel quantity indicator must be calibrated to read "zero" during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);

§23.959 Unusable fuel supply.

(a) The unusable fuel supply for each tank must be established as not less than that quantity at which the first evidence of malfunctioning occurs under the most adverse fuel feed condition occurring under each intended operation and flight maneuver involving that tank. Fuel system component failures need not be considered.

Regulations in 1936 were either identical or very similar.

see:
http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=3b903689cc55804124f8563b0ed49d04;rgn=div5;view=text;node=14%3A1.0.1.3.10;idno=14;cc=ecfr

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on December 11, 2011, 10:49:43 PM
But the TIGHAR hypothesis is that they landed on Gardner with fuel on board. IF they had filled that last tank at Lae, wouldn't this just mean they would have had more fuel in the tank when they landed?  It's not like AE flew around until her tanks went empty then crashed into the sea. The post loss radio messages say otherwise.
Yes, if you accept TIGHAR' hypothesis, which you may have noticed, I don't.

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on December 11, 2011, 10:53:28 PM
Is there a record of her asking what shape the new unpaved strip was in?
Since we now know that the Coast Guard landed two drums of 100 octane, this issue is moot, but to make this inquiry complete I have attached a radiogram from Itasca to Earhart dated June 25, 1937 showing the lengths of the runways at Howland, the longest being 4100 feet.

gl
Title: Re: Octane Analysis
Post by: Irvine John Donald on December 11, 2011, 11:57:37 PM
Thanks Gary for that explanation on gas gauges and fuel tanks. Very clear explanation for non aviators like myself.

Regarding the radiogram to AE, do we know that she received it?  Do we know if it affected her decisions in regards to preparations to leave Lae?

As a non aviator perhaps you could also clarify for me which of the runways she was "likely" to use for take off. Were there three?  They mention 4100 ft, 2600 ft and 2250 ft. They also note prevailing winds out of the east and adding 300 ft to one of the runways to give it a total of 2750 ft. However adding 300 ft to any of the runway lengths listed doesn't give any of them a total of 2750 ft. And the radiogram says 300 feet is "being added", not "have" added or "will have added by the time you arrive".   What am I missing?
Title: Re: Octane Analysis
Post by: Gary LaPook on December 12, 2011, 04:29:27 AM
Thanks Gary for that explanation on gas gauges and fuel tanks. Very clear explanation for non aviators like myself.

Regarding the radiogram to AE, do we know that she received it?  Do we know if it affected her decisions in regards to preparations to leave Lae?

As a non aviator perhaps you could also clarify for me which of the runways she was "likely" to use for take off. Were there three?  They mention 4100 ft, 2600 ft and 2250 ft. They also note prevailing winds out of the east and adding 300 ft to one of the runways to give it a total of 2750 ft. However adding 300 ft to any of the runway lengths listed doesn't give any of them a total of 2750 ft. And the radiogram says 300 feet is "being added", not "have" added or "will have added by the time you arrive".   What am I missing?
The takeoff speed of the plane at 16,500 pounds without the use of flaps was 104 mph and with 30° flaps it was 95 mph. The two computed takeoff distances at sea level and no wind are 2,600 and 2,100 feet, respectively. A headwind on takeoff shortens the takeoff distance because the airplane only has to accelerate to a lower ground speed in order to reach flying speed. Using the Electra as an example, it can take off at 95 mph. If it lines up on the runway facing a 20 mph headwind then there is already 20 mph of air going over the wings so the plane will only have to accelerate an additional 75 mph in order to take off. This takes fewer seconds and the seconds that are saved would have been seconds near the end of the takeoff when the plane would be moving fast. This 21% of takeoff speed wind would result in a 38% reduction of takeoff distance so the plane could take off in only 1302 feet into a 20 mph wind.  A 10 mph wind would result in a 20% reduction allowing a takeoff in only 1680 feet.
If there is no wind then you use the longest runway, 4100 feet on Howland. If there is a strong enough cross-wind to make airplane control on the takeoff roll difficult then the strong wind will allow a takeoff on the shorter runway that faces into the wind.
We also know that the plane would be a lot lighter on takeoff at Howland so would have a shorter takeoff distance, see:
https://tighar.org/smf/index.php/topic,528.msg7061.html#msg7061

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on December 12, 2011, 10:05:54 AM
Jeff,
"PLANK... service."

In my prior post I wrote, "I'll leave you with just one word, PLANK.  ;)," I was just being humorous and I fully expected that you would recognize the standard aircraft engine thermodynamic formula for computing horsepower by the use of "PLANK." Since you didn't even recognize this standard formula, I now take it that you never learned how to compute horsepower and this probably  explains your misunderstanding of the power settings contained in the P&W TCDS E-143 and in the P&W power setting table for the S3H1 engine. I thought that this formula was taught to all A&Ps (you are an Airplane and Powerplant Mechanic, right) so did you miss class that day, or what?
I have attached the FAA test questions for the A&P General Exam, try questions 34, 36, 37, 38, 44 and 57 as a review.
As long as we are at it Jeff, since you also post about Noonan's navigation, I have attached the FAA Flight Navigator test questions, let me know how you do on them.

gl

Gary,

No, I didn't miss school that day.  Did you miss moot court?  Something's left wanting here...

I had referred to a gentleman who happened to be a 'plank owner' and made the mistake of thinking somehow you'd picked-up on that - he happened to have been an original Hurricane Hunter and taught me much in my career.  Sorry, oddly enough I thought you were complimenting the gentleman's navy career and inferring something about your own.  Yes, he was a 'PLANK'.  That's a small stage.

You "take it" wrongly in deciding by that that I do not 'know' the formulae, etc. by my simply missing your 'meaning'.  Conclude as you will, but no, I didn't miss class 'that day' and in fact got sterling marks for mastering that (power calculations for application in cert data, practical applications etc.) and many other formulae - in A&P school and later in Engineering school.  I just didn't think of the 'handy-dandy-ditty' you are apparently accustomed to throwing about on this occasion.

I also have no problem well understanding the data in the TCDS E-143 - and find it tiring that you continue to try to impeach all who disagree with you as a matter of course.  Actually you could use a 'brush up' with applying that data -

You should have recognized the effects of boost (via supercharger) on the Wasp long ago but in all I've seen you point out you've focused almost solely on HP numbers and never seemed to grasp the effects of intake pressure and what effect it has on... the 'thermodynamic' model for one... and how that model would be applied to what goes on in a 'low compression' engine like NR16020 had.  You seem to have sailed right past all the facts of 'mass' as a function in the equation.  Physician, heal thyself - your practical grasp could use some polish.  Meanwhile I think I'll just hang on to my appendix...

Thanks for the 'nav challenge' - I'm sure I'll enjoy the new exercise when I find the time.

And once again we have a thread that has tortured itself into the weeds and far beyond much of anything useful to the search at-hand.  I should be a better man and just ignore it I guess.

LTM -
-------------------------
I'm glad you took my little "ribbing" as intended.  ;)
I appreciate our exchanges.

gl
Title: Re: Octane Analysis
Post by: Gary LaPook on January 10, 2012, 03:53:10 PM

Besides, as suggested before - it is getting knuckle-headed for us to clutter up this string with the administrivia of dicephering Rev. 4 of this TCDS from 1973 - published at least 4 iterations and 36 years after AE's particular Wasps disappeared... and with no particular gain to the topic that I can see...

I tried to get the original TCDS and power setting chart from my contacts at P&W and I received this response today:
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From: NXXXXX, George G PWC [mailto:George.NXXXXXXXXX]
Sent: Tuesday, January 10, 2012 12:52 PM
To: Gary J. LaPook
Subject: RE: Amelia Earhart Engine

Happy New Year to you too Gary.  Trust everything is well with you.

We have done a quick search (no data base exists for such ancient stuff) to see whether we could locate a copy of the original type certificate E-143 for the Wasp S3H1 (Military R-1340) but were unable to find any.  The originals are and always were with Pratt & Whitney in Hartford,  Connecticut.  You could perhaps contact them or better still the FAA.

P&WC had (probably still valid today) Canadian Department of Transport Type Certificate E3 for the Wasp S3H1 model engine as well as a number of other Pratt & Whitney radial engine models.

P&W Hartford ceased radial engine manufacture in the mid to late 1950’s and transferred production to P&WC (Canadian Pratt & Whitney Aircraft Co. Ltd. as we

were called at that time).

As far as the power setting chart for the Wasp S3H1 we are sure that it could be found in one of the relevant manuals which are buried somewhere in the archives and would require quite a search.

Sorry but this is the best we can do without a lot of digging but if there is anything else let us know and we will try to help if we can.

Regards

George
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gl
Title: Re: Octane Analysis
Post by: Erik on January 11, 2012, 05:47:01 PM
More evidence to support contemporaneous belief that 100 octane provided more power.  Regardless of its true results, did AE "believe" in it?

From 1937 issue of Flight weekly publication: (first paragraph)
"Ricman and Merrill for the first time took advantage of the added power and range made possible by the use of 100-octane fuel."