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Author Topic: Fuel load, head winds, range  (Read 53143 times)

Gary LaPook

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Re: Fuel load, head winds, range
« Reply #15 on: August 15, 2011, 02:38:38 PM »


I believe that the Chater Report states that all tanks were filled except one 81 gallon tank that was for 100 octane fuel and it was half full (40.5 gallons).  The reason that the 81 gallon, 100 octane tank, was not filled (topped off) was because Lae had no 100 octane fuel.

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

There is definitely a conflict in the evidence regarding the fuel consumption. The tanks only held 1150 U.S. gallons so that puts an absolute top limit on the gas in the plane. Chatter said that 654 Imperial gallons (785 U.S. gallons) were put into the tanks so this puts an absolute floor on the fuel load of 785 U.S. gallons.

Both Collopy and Chatter state that the plane had 1100 U.S. gallons on board but there is a conflict in their statements. Collopy said that a 100 gallon tank was half full while Chatter said an 81 gallon tank was half full. There are no 100 gallon or 81 gallon tanks in the fuselage but there are 102 gallon and 81 gallon tanks in each of the wings. Earhart lost control of the plane on takeoff from Hawaii so she would be loath to have a lateral fuel imbalance on takeoff at Lae so is likely that she wouldn't just leave one tank in just one of the wings half full but would leave a tank on the other side half full also. Supporting this theory is the discrepancy in the size of the tanks described by Chatter and Collopy. If one of them looked in the tank and passed the information on the other guy then they would have the exact same size for the tank so it didn't happen this way. If they each looked in the same tank that was half full then, again,  they would have reported the same size. Based on this it is reasonable that they were each looking in different tanks, one in the right wing and one in the left wing. They both said they saw a tank half full and if they talked to each other neither would have reason to realize that the other guy was talking about a different tank since they both calculated 1100 gallons total. It is like the old story of the three blind men examining an elephant. Based on this I believe that it is quite likely that they only had about 1050 U.S. gallons on board when they took off from Lae.

This 50 gallons less explains only between about one hour to about two hours  of the lesser endurance but doesn't explain all of it. Using the data from Lockheed shows there should have been plenty of gas left at 2013 Z and the Breguet formula also, independently, predicts much greater range so it doesn't make sense that they ran out shortly after 2013 Z, so this is quite frustrating.

But there is another piece of conflicting evidence that trumps all the other calculations, this is Earhart's statement that they only had a half hour of gas left. She was there, and the change in the pitch of her voice lends additional credence to her being almost out of fuel when she transmitted the last message at 2013 Z.

gl
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h.a.c. van asten

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Re: Fuel load, head winds, range
« Reply #16 on: August 15, 2011, 02:50:44 PM »

From the Bréguet formula derived is , for the mean speed of A/c  Vm = Range / Endurance = V0 {[ln (W0/W1) / 2[(W0/W1)^0.5 -1]} . For W0 = 16,500 lb , W1 = 16,500 - (1028 x 6 lb (gas) + 268 lb (oil)) = 10064 lb . For Vm follows  0.4944/0.5609 = 0.884 V0 . For V0 = 155 mph we find Vm = 137 mph , in keeping with Vgm = 137 mph for 2,628 mls offset included in 19h12m . This says that due to the actual windspeeds aloft the fuel weight diminished faster than expected from forecast : 2,628 mls / 18 hrs = 146 mph cross country lowered to 2,628 mls / 19h12m = 137 mph .
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Gary LaPook

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Re: Fuel load, head winds, range
« Reply #17 on: August 15, 2011, 03:05:15 PM »

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

Wow Jeff, I just realized that you must be very, very old! I think the last time an A&P worked on a steam powered airplane it was Langley's in 1903. ;)

gl


Well, I'm pretty old I guess, but I'm afraid Langley pretty well predated the first A&Ps. 

Actually, my first mechanical love as a boy was steam locomotives - but I was born too late to experience them on a common scale (so not THAT old).  I learned all I could through the library and every other source I could find.  Always loved steam powered ships - the compound / triple expansion recips and Parsons turbines, etc. all fascinated me.  Have seen the guts of the N.S. Savannah as a small boy - and again as a young man - several times (you may know, she's nuclear powered, not bunker or coal - but 'steam' none-the-less).  I have spent quite a bit of time perusing the Norwich City information and pictures of her on this site and elsewhere - from proud 'tramp' to forelorn derelict.

The idea that something bigger than a house and made to the precision of a fine watch could sit in the guts of a ship and drive something like the Titanic across the ocean (well, part way as it turned out...) at 22 knots or more has always been enchanting to me.  And she was a wonder in her day - two recips and one turbine - all circuited to get the most out of the heat from her boilers.  The behavior of fuel, air and water to make it happen was equally as thrilling a pursuit.

It's been a long time since I was much of an active A&P.  Now my work is done on paper and revolves around 'kerosene' (Jet A) and modern turbofans - but I still enjoy those steam roots and the thoughts of all that grand machinery from the past.  Look at the legacy we have from it all! 

I'd love to see the examples you wrote of in California some day; I never tire of it.

LTM -

-----------------------------------------------
-------------------------------------
I remember the excitement when the Savannah was launched, too bad it was an idea who's time never came. You can also go aboard the first boat with that type of tea kettle when you are in Groton, Conn., the 571 boat.
I am attaching two photos, one of the links, and the other a diagram on the engine on the Jerimiah O'Brien. There is also a photo of the Walschaerts gear on a Big Boy in Ohaha (woman for scale.)

gl

gl
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h.a.c. van asten

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Re: Fuel load, head winds, range
« Reply #18 on: August 15, 2011, 03:27:58 PM »

Vt/F.(1 - Vw/Vt) is the fuel flow rate fromula for in head- or equivalent crosswinds , the term in brackets is the wind regression factor . For this we find f = 0.905 for the forecast wind speeds and directions , giving 1/0.905 = 1.105 , or 10 1/2 % for the factor by which the initial supply had to be multiplied for 2,750 mls in the headwinds . Noonan , at the July 1 press conference , said to take in 950 gallons for 2,750 mls in still air . 950 galls x 1.105 = 1,050 87-octane . Add 50 galls 100 octane and the result is 1,100 US galls at apron Lae Airport , in accordance with the Collpy - Ivedale testimonies .
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h.a.c. van asten

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Re: Fuel load, head winds, range
« Reply #19 on: August 15, 2011, 03:44:13 PM »

(1,100 - 25 - 1,028) galls = 47 galls , 25 of 100 oc & 22 of  87 oc , this latter for 1/2 hour @ nominally 44 gph low speed low altitude is a reasonable match with " 1/2 our left" @ 1912 GMT . If only 27 gals were left for 5 galls 100 oct remaining , additional endurance was also 1 / 2 hr if reckoned with the specific hourly consumption  1,028 galls / 19h12m = 53.5 gph .
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h.a.c. van asten

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Re: Fuel load, head winds, range
« Reply #20 on: August 16, 2011, 12:43:51 AM »

Somewhere in the 487 Report there must be an underestimate , probably for continuous headwind Beaufort 6 translating to to 3rd power effect on energy needed , but I have not yet found the omission , the SFC/hr/hp figures should by recomputation deliver the outcome .
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Jeff Scott

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Re: Fuel load, head winds, range
« Reply #21 on: August 16, 2011, 10:50:17 PM »

But, she said she only had a half hour left...............

gl

Which, of course, leads to the inevitable dispute over what that statement means:  did she literally have only 30 minutes worth of fuel left or only 30 minutes left until she had to start using her reserve?
It's not too late to be great.
 
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h.a.c. van asten

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Re: Fuel load, head winds, range
« Reply #22 on: August 17, 2011, 01:04:42 AM »

It was for the fuel for the fuel as planned for the flight , not for the special avgas reserve , since GMT 1815 - 1912 = 1h03m .
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h.a.c. van asten

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Re: Fuel load, head winds, range
« Reply #23 on: August 17, 2011, 01:31:16 AM »

If , p 12 Rep.487  / graph you take the fuel figures for 1,050 & 1,100 stores , and divide 3,645 and 3,800 mls range by factor 1.44 shown earlier for 3rd power effect , you get resp. 2,531 mls and 2,639 mls , the first close to 2,556 , the latter close to 2,628 mls , zero wind . This supports that Rep 487 registered marginally for continuous adverse wind as during the actual flight .
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Harry Howe, Jr.

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Re: Fuel load, head winds, range
« Reply #24 on: August 17, 2011, 01:40:35 PM »


Perhaps the 1/2 hour fuel comment didn't really happen but was "invented" after the fact to cover butts and justify the ship steaming off to the NW and the "Search"  being done there primarily.

If I remember correctly, the men in the Radio Shack didn't hear that transmission Someone came in from the deck and asked those in the radio room whether they heard her.  "She was just on, didn't your hear her?"
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
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Martin X. Moleski, SJ

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Re: Fuel load, head winds, range
« Reply #25 on: August 17, 2011, 02:21:41 PM »

Perhaps the 1/2 hour fuel comment didn't really happen ...

From "The 1937 Search: The First 24 Hours"  by Randall S. Jacobson, Ph.D.:

Thompson’s actions apparently were based upon his conviction that Earhart had said, at 07:42 (1912 GMT), that she only had half an hour of fuel left. Because there is no land other than Howland and its sister island Baker which could possibly be reached within that fuel limitation, the conclusion that the  airplane went down at sea is inescapable. If the quote is accurate Thompson  was certainly correct in beginning the search rather than sitting at Howland  waiting for an airplane that was already in the water. Where does the  quotation come from? The only source is what Thompson calls the “Other Log” which he quotes in his July 19th report as saying “Earhart on now  says running out of gas only 1/2 hour left.” The entry was made by Radioman 3rd Class O’Hare who had been on watch since 02:00. Evidence that the phrase was not said includes:
  • Radioman 3rd Class Galten’s entry in the Itasca’s radio log, “KHAQQ calling Itasca. We must be on you but cannot see you but gas is running low. Been unable reach you by radio. We are flying at a 1,000 feet.”11
  • An entry in the Itasca’s deck log by Lt. (jg) W. J. Sevarstan, “0742 Planes position reported as near the island and gas running low.”
  • Lt. Cooper’s report, “0741. Earhart. We must be on you but cannot see you but gas is running low...”12 However, this is a second-hand report, as Cooper was still on Howland Island.
  • The July 4th press release sent by Itasca, “0730 Quote we must be on you but cannot see you but gas is running low...”13
  • At 08:43 (2013 GMT), a full hour after Earhart supposedly said she had “only 1/2 hour gas left,” Earhart was still aloft and transmitting.
  • Not once in the three messages received by Itasca after the 07:42 message did Earhart repeat her concern over fuel.
  • In Thompson’s typed report the quote from the “Other Log” is followed by the parenthetical comment “(unverified as heard by other witnesses)” but the “un” in “unverified” has been lined through by hand.14 However, it is impossible to determine when this line-out occurred and/or whether it was there when originally delivered to the Coast Guard.
  • The available evidence argues strongly that the phrase “½ hour gas left” was never said. It may,  in fact, have been a simple misunderstanding. In three of the nine transmissions heard by Itasca, including the next message received 16 minutes later, the ship’s radio log recorded Earhart’s use of the phrase “half hour,” but always in reference to the radio schedule, never to fuel.
LTM,

           Marty
           TIGHAR #2359A
 
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h.a.c. van asten

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Re: Fuel load, head winds, range
« Reply #26 on: August 17, 2011, 02:50:51 PM »

@ GMT 1912 Earhart , communicating that for 1/2 hour fuel was left , referred to the fuel store as planned for the flight to destination , not to the 100 octane gas in the separate container . The fuel for 1/ 2 hour as by re-computation must have amounted to +/- 22 gallons whereas ;  if 16 galls 100-oct remained , also the GMT 1815 fuel run out time finds explanation . At GMT 1945 no on cue radio signal was on air from A/c : at that point of time regular avgas was exhausted and cocks had to be set for flow from the 100 oct reserve ; shifting to the proper line disabled the pilot for operating the microphone .
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Jeff Scott

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Re: Fuel load, head winds, range
« Reply #27 on: August 17, 2011, 09:43:19 PM »

The 100 octane tank was *not* her reserve.  By all accounts, Earhart routinely carried at least 20% more fuel than required to reach her destination on all her previous flights.  This fact is borne out by her carrying enough fuel for 24 hours flight time even though the trip to Howland only took 19-20 hours.  That 4-5 hours extra fuel was her reserve, far more than the 100 octane supply alone.
It's not too late to be great.
 
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h.a.c. van asten

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Re: Fuel load, head winds, range
« Reply #28 on: August 18, 2011, 01:03:51 AM »

The reserve based on the forecast weather was 10.5% , the 100-oc gas was for take off in low density air due high temperatures @ Lae & Howland .
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Gary LaPook

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Re: Fuel load, head winds, range
« Reply #29 on: August 18, 2011, 03:52:04 AM »

Perhaps the 1/2 hour fuel comment didn't really happen ...

From "The 1937 Search: The First 24 Hours"  by Randall S. Jacobson, Ph.D.:

Thompson’s actions apparently were based upon his conviction that Earhart had said, at 07:42 (1912 GMT), that she only had half an hour of fuel left. Because there is no land other than Howland and its sister island Baker which could possibly be reached within that fuel limitation, the conclusion that the  airplane went down at sea is inescapable. If the quote is accurate Thompson  was certainly correct in beginning the search rather than sitting at Howland  waiting for an airplane that was already in the water. Where does the  quotation come from? The only source is what Thompson calls the “Other Log” which he quotes in his July 19th report as saying “Earhart on now  says running out of gas only 1/2 hour left.” The entry was made by Radioman 3rd Class O’Hare who had been on watch since 02:00. Evidence that the phrase was not said includes:
  • Radioman 3rd Class Galten’s entry in the Itasca’s radio log, “KHAQQ calling Itasca. We must be on you but cannot see you but gas is running low. Been unable reach you by radio. We are flying at a 1,000 feet.”11
  • An entry in the Itasca’s deck log by Lt. (jg) W. J. Sevarstan, “0742 Planes position reported as near the island and gas running low.”
  • Lt. Cooper’s report, “0741. Earhart. We must be on you but cannot see you but gas is running low...”12 However, this is a second-hand report, as Cooper was still on Howland Island.
  • The July 4th press release sent by Itasca, “0730 Quote we must be on you but cannot see you but gas is running low...”13
  • At 08:43 (2013 GMT), a full hour after Earhart supposedly said she had “only 1/2 hour gas left,” Earhart was still aloft and transmitting.
  • Not once in the three messages received by Itasca after the 07:42 message did Earhart repeat her concern over fuel.
  • In Thompson’s typed report the quote from the “Other Log” is followed by the parenthetical comment “(unverified as heard by other witnesses)” but the “un” in “unverified” has been lined through by hand.14 However, it is impossible to determine when this line-out occurred and/or whether it was there when originally delivered to the Coast Guard.
  • The available evidence argues strongly that the phrase “½ hour gas left” was never said. It may,  in fact, have been a simple misunderstanding. In three of the nine transmissions heard by Itasca, including the next message received 16 minutes later, the ship’s radio log recorded Earhart’s use of the phrase “half hour,” but always in reference to the radio schedule, never to fuel.

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

It is Friday evening and you are leaving the office. One of your office mates suggests that a few
of you stop for a beer at the sport bar that is on your way home. So you guys stop for a beer and
while ordering a second round, watching a Cubs game on the big screen TV, you strike up a
conversation with a stranger standing at the bar. He introduces himself as “Jim.”.  He says he just
recently moved to this town and asks you if there are any good restaurants in the area. You say to
him, “I live down near  the corner of First Avenue and Main Street and there are a number of
very good restaurants right at that corner.” Jim says, “wow, that is good to know,  I live at Third
and Main so those restaurants will be convenient for me and my wife.”

When you get home you tell your wife that you met a newcomer named “Jim” and “that he lives
at Third and Main.” Later you tell your son about this meeting and tell him, “Jim lives close to
us.”

The next Friday you are again at the same bar and this time you meet “Bill.” Pretty much the
same story as with Jim and you tell Bill the same thing, “I live down near  the corner of First
Avenue and Main Street and there are a number of very good restaurants right at that corner.”
Bill says, “that is good to know since I live close to there.”

You go home and tell your wife about this meeting.  You tell her, “Bill lives close to us.” But
you cannot say to her the same thing you told her about Jim something like “Bill lives at the
corner of Third and Main” because you do not have that piece of detailed information. If you just
made up a detail like that then you would be lying.

In Jim’s case, both of your two statements tell the truth, you know from his address that he “lives
close to you” so your generalized paraphrasing of his actual words is still telling the truth and is
commonly done, especially when making notes. But when making notes you do not make up a
detailed “fact” when you only have a general statement to work from. Think back on your own
experience, I’ll bet that you have often paraphrased information into a general form but that you
haven’t made up detailed “facts” from just a general statement.

One of the radio logs contains:  “Earhart on now, says running out of gas, only ½ hour left, can’t
hear us at all.”


The other log records: “We must be on you but cannot see you, but gas is running low, been
unable to reach you by radio.”

If Earhart had said only “gas is running low” or “running out of gas,” if you were the radio
operator would you have made up the specific and detailed “only ½ hour left” and entered it in
your log? I thought not.

Or is it more likely that she actually said "half hour of fuel left" and the other radio operator
paraphrased that to the more general "running low on fuel?" Writing down a more general
summary  from a specific statement is still speaking the truth, a ”half hour left” IS “running out
of gas.” But going the other way means "making up" the "half hour" fact and so is NOT a true
statement if she didn't actually say it

The Niku people and the Mili people and the New Britain people do not like Earhart’s statement
but if your keep an open mind I think you will agree she most likely actually said “only ½ hour left.”


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

But she was still flying a full hour after her statement was logged so is this proof that she did not
say “only ½ hour left?”

Well, no.


The fact that the fuel lasted an hour after Earhart reported only one half hour left is unsurprising.
Fuel gauges in airplanes are notoriously inaccurate today and they were no better 74 years ago.
Federal regulations (posted below) requires that the fuel gauge only has to  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 such as holding the nose extremely high or in
slipping or skidding flight or if doing aerobatics. You can use this "unusable fuel"
if you fly at normal flight attitudes. Another way to look at this 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 if you maintain
normal flight attitudes.  So if Earhart looked at the fuel gauge and estimated that there was only a
half hour left until it reached "zero" then it is not surprising at all that there was an additional half
hour of "unusable fuel” remaining after the gauge got down to "zero" and that this “unusable
fuel”continued to feed the engines  since they were not doing any extreme maneuvering.

Here are the current Federal Aviation Regulations found in title 14 of the Code of Federal
Regulations “CFR.” Part 23 prescribes the requirements for certification of airplanes such as
Earhart’s Electra.  Prior to the current Federal Aviation Regulations, aircraft had to meet the
requirements in the Civil Air Regulations, Part 3. CAR 3.437 and CAR 3.672 spelled out the
exact same requirements for fuel gauges.

14 CFR 23.1553:


§ 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.

see:

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=f0270f2e0237f7e8240bd450104e78e0&
rgn=div8&view=text&node=14:1.0.1.3.10.6.100.17&idno=14


gl
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