TIGHAR
Amelia Earhart Search Forum => Aircraft & Powerplant, Performance and Operations => Topic started by: Irvine John Donald on June 04, 2011, 04:03:47 PM
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One of the main issues, as I see it, with the Navy and Coast Guard search theories is the whole discussion on fuel consumption. The evidence suggests the AE had the proper fuel reserves for the trip and the knowledge to manage her power plants effectively. My question for the forum members is simple, if you're knowledgeable in such matters as "flying". With the instrumentation of the day, could AE have been burning though her reserves much faster than she thought? Was the Electra capable of burning 25% more fuel per hour than normal without doing serious damage to the power plant? If AE determined early on in the flight, by reading fuel gauges, that she was using more fuel than expected, would she the not have aborted the attempt and found nearest airfield to set down on? It seems to me that because she didn't abort that her fuel was burning at the expected rate and she therefore had the fuel reserves at Howland that she expected.
I ask because it seems like this is one of the key search criteria used. One school of thought being the radio messages suggesting she had one half hour of fuel left at Howland. Therefore spend huge amounts of the overall time searching locally for a ditched aircraft.
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One of the main issues, as I see it, with the Navy and Coast Guard search theories is the whole discussion on fuel consumption. The evidence suggests the AE had the proper fuel reserves for the trip and the knowledge to manage her power plants effectively. My question for the forum members is simple, if you're knowledgeable in such matters as "flying". With the instrumentation of the day, could AE have been burning though her reserves much faster than she thought? Was the Electra capable of burning 25% more fuel per hour than normal without doing serious damage to the power plant? If AE determined early on in the flight, by reading fuel gauges, that she was using more fuel than expected, would she the not have aborted the attempt and found nearest airfield to set down on? It seems to me that because she didn't abort that her fuel was burning at the expected rate and she therefore had the fuel reserves at Howland that she expected.
I ask because it seems like this is one of the key search criteria used. One school of thought being the radio messages suggesting she had one half hour of fuel left at Howland. Therefore spend huge amounts of the overall time searching locally for a ditched aircraft.
Airplane fuel gauges are notoriously unreliable. They say the only time you should believe them is when they read empty.
From the old Forum: (http://From the old Forum:)
Date: Wed, 17 Nov 2004 12:48:23
From: Ric Gillespie
Subject: Re: AE's Fuel
> How did Earhart track her fuel consumption on her flights? What
> instruments or other advice would they have received (from Johnson,
> Mantz or others)?
We know that the plane was equipped with a Cambridge Exhaust Gas Analyzer and that it was considered crucial to fuel management. We also know that they completed all of their previous legs without running out of gas or even having to make an unplanned landing enroute to refuel, so it seems safe to say that they were able to monitor their fuel situation adequately and that, by the time they got to Lae, they had lots of experience doing it.
> Do we know how they tracked their fuel on the other legs of the flight?
As far as I know, AE never specifically wrote about it but it seems safe to assume that she (not Noonan) tracked her fuel the same way everybody else did. You how much gas you started with. You know from the book, verified by experience, how much fuel your engines use at given combinations of manifold pressure and mixture. You subtract what you presume you have used from what you started with and that's how much you've got left. If the fuel gauges pretty much agree with your calculations so much the better. If not, you either have a leak or the gauges are wrong. It ain't rocket science.
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Thank you Marty. Very informative and makes me wonder how some technologies don't seem to advance as much as others. You would think that in today's world we could hope for better.
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Thank you Marty. Very informative and makes me wonder how some technologies don't seem to advance as much as others. You would think that in today's world we could hope for better.
The problems of measurement of any quantities of any kind whatsoever is an art and science all to itself. (http://en.wikipedia.org/wiki/Metrology)
The problems of reliably indicating the amount of fuel present in tanks of varying sizes and shapes under wildly varying conditions of temperature, vibration, and turbulence are not trivial.
Besides designing some kind of ideal sensors that are reasonably priced, that can survive in a hostile environment, and that accurately model the amount of fuel in a tank of a particular shape, that system needs to be calibrated and maintained in calibration for a particular aircraft: "Aircraft Fuel Gauge Accuracy." (http://www.av8n.com/fly/fuel-gauges.htm)
If we imagine a perfectly uniform container (a cylinder or a cube) on a laboratory table, all you need is a visual ruler (a float, a set of lines etched on the class) to know with a reasonable degree of precision how much liquid is in the container.
Now make that container into an airfoil shape so that it will fit into a wing section. Or cast it into the form of a tip tank. Set the contents in motion in that irregularly-shaped tank. Let the fuel foam and slosh forwards and backwards and undergo plus and minus G forces not only up and down but from side-to-side in various trajectories (a coordinated turn versus a slip, for example).
How many of these multiple forces and conditions will the model used by your system take into account? With you equip it with accelerometers and gyros (more parts that can fail!) to smooth out errors caused by these variables? How often will you update the display if it is digital? By what means will you transmit the information if the system is analog? What kinds of errors are introduced into the system by the methods of transmission of information that you choose?
What kind of safety margins do you want to build into your system? Do you want to deliberately err on the side of caution, so that when the gauge reads "E" there is still a little bit of usable fuel left? Or do you want the prop to stop turning at the same time the needle hits bottom?
Gasoline expands when it is hot and contracts when it is cold. Will you add a temperature correction to your system so that it accurately reflects fuel by weight instead of by volume?
Suppose you decide to use a float as your basic gauge. When the tank is full, the float is highly accurate. No float can keep floating when the gas gets low. At some point, the float hits bottom while there is, perhaps, some usable fuel still in the tank but not enough to keep the float up. How much gas is that? Should you put the float into its own cylinder that goes deeper than the bottom of the tank? Should you try to isolate it from the wave action in the tank? By what means do you measure and report the height of the float? Do you average a set of readings periodically or simply let the gauges shiver with the changing conditions?
I am not a pilot.
I fly radio-controlled airplanes.
I read a lot about aviation.
I'm not sure that I've indicated all of the variables correctly.
I imagine that today's gauges are, on average, better than those of 1937. Persuading pilots to use all of the information at their disposal to make sure that they don't run out of gas until after landing seems to be one of the best ways to improve aviation safety, but there seems to be room for improvement.
A friend of mine--an A&P and a CFI--took off on a short hop in a Taylorcraft to reposition it for delivery to a customer. He ran out of fuel very shortly after takeoff, tried to turn back to his runway, and destroyed the plane among some trees. To this day, he swears that there should have been five gallons in the aircraft and he is convinced that someone stole the gas. Nevertheless, he should have stuck a stick in the tank before he took off--the most primitive and effective method of making sure that there is gas available at the start of a flight (as a general rule--I guess that even sticks can be deceived).
I am an armchair pilot. I serve in the battalion of Captain Hindsight. I survey the results of others' mistakes. I know what they should have done differently. I'm not putting my money where my mouth is. You may take the things I say with as much salt as your doctor allows in your diet. :D
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LJ.Dnld . The fist leg of 874-900 mls asked 10% more fuel burnt whereas a 44 mintes delay on ETA-Nukumanu was incurred . Recomputation (1996) showed that @ 1912 GMT the reserves were sufficient for 1h05m , the 100 oct special avgas included . The hourly mean gas consumption was (1,100 US gals.) / 20h17m = 54 gls. These figures when fed into the entire , 2729 mls , flight´s performance formula give good compliance with 20 mph averaged headwinds and groundspeed 134-136 mph. 154 mph /54 gph ( 1 - 20 mph /154 mph) = 2.48 mpg , 2 mls taxi-and-run distance included. [154 mph = Ind.Air Speed , 54 gph = US gls/hr , 20 mph = av.equiv. headwinds]. The 1996 inquiry needs updating due to new vistas but however , figures given will not essentially decline. Initial fuel loaded was 1,050 gls 80 oct + 50 gls 100 oct (remaining after Lae take off).
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Off topic, but as an engineering curiosity and a follow up to Marty's post, here's one way to measure fuel level in a tank. Sounds ridiculously overcomplicated on the face, but NASA did it in some spacecraft applications, where you have the added problem of no gravity to hold all the liquid fuel at the bottom of the tank.
Completely sealed system. Liquid fuel is contained in a rubber bladder which is inside a larger rigid tank. Pressurize the space outside the bladder with a slightly radioactive gas. Have a sensor that measures radiation. As you use fuel, the bladder shrinks, the radioactive gas expands, and therefore the space right in front of the sensor will have fewer atoms of the gas in it, hence a lower level of radiation. Run the particle count through a computer and presto: you have yourself a nice gas gauge.
I woulda thought you could have done it by measuring the pressure in the tank and correcting for temperature, but then again I'm not a rocket scientist.
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Off topic, but as an engineering curiosity and a follow up to Marty's post, here's one way to measure fuel level in a tank. Sounds ridiculously overcomplicated on the face, but NASA did it in some spacecraft applications, where you have the added problem of no gravity to hold all the liquid fuel at the bottom of the tank.
Completely sealed system. Liquid fuel is contained in a rubber bladder which is inside a larger rigid tank. Pressurize the space outside the bladder with a slightly radioactive gas. Have a sensor that measures radiation. As you use fuel, the bladder shrinks, the radioactive gas expands, and therefore the space right in front of the sensor will have fewer atoms of the gas in it, hence a lower level of radiation. Run the particle count through a computer and presto: you have yourself a nice gas gauge.
I woulda thought you could have done it by measuring the pressure in the tank and correcting for temperature, but then again I'm not a rocket scientist.
They may have started with the bladder first as a solution for getting the fuel to flow in a zero-G setting, then realized that they could create a radioactive dipstick as icing on the cake.
Control-line pilots have used pressurized fuel cells inside of tanks for many years. I don't know whether their technology precedes NASA's.
"Combat and some speed models use rubber tubing ('bladder' tank) , baby pacifiers, or fountain pen ink bladders, inflated with fuel in a veterinary syringe, to hold the fuel under fairly high pressure. The fuel line is pinched off to prevent fuel loss until the engine is started. The high pressure of fuel delivery permits the use of a larger intake on the engine, allowing more air flow than would otherwise be possible, and thus more power. The fuel delivery is very steady with this method until the very last bit of fuel runs out, but is logistically difficult because any leak results in streams of fuel spraying out" ("Control Line," Wikipedia) (http://en.wikipedia.org/wiki/Control_line).
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Chr.Owns. Seems easier to hire an anaerobic garden gnome who continuously by GSM reports until what body part he stands in the fuel , fly as cautiously as possible : no waves permitted , never fuel to full.
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???
*goes back to pondering the many mysteriesl of Amelia*
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Chr.Owns. Seems easier to hire an anaerobic garden gnome who continuously by GSM reports until what body part he stands in the fuel , fly as cautiously as possible : no waves permitted , never fuel to full.
Ummmmm....what?
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One of the main issues, as I see it, with the Navy and Coast Guard search theories is the whole discussion on fuel consumption. The evidence suggests the AE had the proper fuel reserves for the trip and the knowledge to manage her power plants effectively. My question for the forum members is simple, if you're knowledgeable in such matters as "flying". With the instrumentation of the day, could AE have been burning though her reserves much faster than she thought? Was the Electra capable of burning 25% more fuel per hour than normal without doing serious damage to the power plant? If AE determined early on in the flight, by reading fuel gauges, that she was using more fuel than expected, would she the not have aborted the attempt and found nearest airfield to set down on? It seems to me that because she didn't abort that her fuel was burning at the expected rate and she therefore had the fuel reserves at Howland that she expected.
I ask because it seems like this is one of the key search criteria used. One school of thought being the radio messages suggesting she had one half hour of fuel left at Howland. Therefore spend huge amounts of the overall time searching locally for a ditched aircraft.
For zero wind 950 US gls was computed, with 10.5 % (regression factor 0.905 airspeed vs groundspeed consumption) addition for equivalent winds the 87 oc amounted to 1,050 gls . Add 50 gls 100 oc in wing tank and fuel load @ take off was 1,100 US . On the Lae-Nukumanu track wind (25 mph east) was out of forecast speed and compass (15 mph s-se) so as to ask 10% addional fuel burn (regress.factor 0.82 instead of 0.905). @ 1912 GMT reserves were : 45 US , 23 of 87 oc , 22 of 100 oc for respective 33 min & 32 min flight time @ 41 gph. Thence, the 1912 Z fuel reserve was 1/2 hour for the 87 oc to finish the flight as planned , plus 1/2 hr for the 100 oc left after take off from Lae. The total reserve was for 1 hour , reasonable for the conditions & expectations given . The to Howland closest land points are Winslow Reef (210 mls) and McKean (350 mls) : neither the one , nor the other was within endurance range, whereas the A/c was not alighted @ Baker (35 mls).
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I researched the fuel supply and management (quantitatively by aircraft performance theory) and published in the magazine of Royal Netherlands Air Force Museum , Soesterberg , 2 issues of 1996 . E.Long arrived at the same 1912 GMT reserves , but did not in his book deliver computations on the subject . The book appeared after 1996 but it is hardly possible that he knew my mentioned articles . H.
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Have you got a link to your article or could you scan it and upload it to the forum for us to view it?
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Articles need some updates , and I have only one of two available here since I am not at my home address now , will try nevertheless . If ready I will post signal . H.
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Articles need some updates , and I have only one of two available here since I am not at my home address now , will try nevertheless . If ready I will post signal . H.
That would be good for the forum!
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LJ.Dnld . The fist leg of 874-900 mls asked 10% more fuel burnt whereas a 44 mintes delay on ETA-Nukumanu was incurred . Recomputation (1996) showed that @ 1912 GMT the reserves were sufficient for 1h05m , the 100 oct special avgas included . The hourly mean gas consumption was (1,100 US gals.) / 20h17m = 54 gls. These figures when fed into the entire , 2729 mls , flight´s performance formula give good compliance with 20 mph averaged headwinds and groundspeed 134-136 mph. 154 mph /54 gph ( 1 - 20 mph /154 mph) = 2.48 mpg , 2 mls taxi-and-run distance included. [154 mph = Ind.Air Speed , 54 gph = US gls/hr , 20 mph = av.equiv. headwinds]. The 1996 inquiry needs updating due to new vistas but however , figures given will not essentially decline. Initial fuel loaded was 1,050 gls 80 oct + 50 gls 100 oct (remaining after Lae take off).
Sry the 100 oct after takeoff Lae was 22 US , not 100 . H
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... As to mixture, we'll never know for sure how good her technique was, but that too should have been elementary enough with the aid of the Cambridge analyzer on board.
She seems to have spent two days in Bandoeng (June 25-26) (http://tighar.org/wiki/Timeline_of_the_second_round-the-world_attempt) just getting the exhaust analyzer working. That suggests to me that she was using it en route, knew when it wasn't working, and wanted to have it in good order for the big over-water legs.
Even failing that instrument, leaning to point of misfire and enrichening to smooth engine again and watching cylinder head temps is almost instinctive.
Agreed. She was, in many respects, an airhead (pun intended; you may laugh now), but she couldn't have made as many long-distance flights as she did (http://tighar.org/wiki/AE) without understanding the basics of fuel and power management.
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she couldn't have made as many long-distance flights as she did (http://tighar.org/wiki/AE) without understanding the basics of fuel and power management.
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I would agree. Bernt Balchen mentions in Come North with Me having calculated a throttle curve for use on her Atlantic solo flight, so we know she was familiar with the concept of progressive power reduction at least as early as 1932. That she was already quite familiar with mixture control by then is implied by her use of mixture settings as a sort of supplemental source of altitude information after the altimeter failed on that flight: taking note of how far back the mixture could be leaned gave a very rough indication of current altitude.
LTM,
Mona
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I forgot the articles on fuel etc. are in Dutch , I will translate them ; article on fuel load (1996 matter of dispute ) first (from "Newsletter" RDAFM , nr.58 , July 1996) and post when finished , soon as possible .
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Yes , but a headwind or equivalent headwind blowing 20 mph sets any specific flown 10E distance per gallon gasoline (rich or lean) back with 13 percent , if your emergency reserve was 10% , you may get 3% short .
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She herself said the 1912 87 oc store to be for 1 / 2 hour , together giving 1h05m with the 100 oc remaining . Normally a 10E could fly at specific 150 mph / 38 gph = 3.94 mls/ gallon . A 20 mph headwind aloft sets this back to 3.43 mpg , or 13% less . On the Lae-Nukumanu leg with 25 mph eastern the mpg figure was set back with 17% . Try : the formula is V ground p.hr / fuel expenditure p.hr = V true airspeed / fuel expenditure p.hr X [ (1 - V wind / V true airspeed)] . Like by cars on the highway , the air resistance is predominant over other resistances in flat country . Doubling your speed asks for 2 to power 3 = 8 times more labour . Maintaining your speed with head-on wind asks for (V-own + V-wind) to power 3 additional labour , at any engine power setting .
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So if there is somewhere between 50 and 100 gallons remaining once landed on Gardner is this enough for several days of running up the engine to charge radio batteries? I think i read something that said the engine had to be run at a setting higher than an idle to run the radio while charging the battery. Does the remaining fuel burned match the number of days of post loss radio messages?
If yes then this lends further credibility to the hypothesis of Gardner being the likely final landing spot. If no then is it because they would have run out sooner than the messages ended, thus casting doubt on the authenticity of the last few post error messages. Or if they had gas for more messages then why did they stop transmitting? Electra went over reef edge into deeper water? Or castaways passed away? Or...
Does the fuel consumption fit the hypothesis? Not to the last drop but at least within the scenario and knowing we dont know the exact burn rate.
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At 1912 GMT about 22 gls 100-oc remained from 50 . The store than was 23 gls 87-oc + 22 gls 100-oc = 45 US . @ 41 gph in low dense air the remaining flight time was 1h05m - 1h06 m . Add to 1912 = 2017 GMT . Before running dry however , carbureters deliver up and down supply . The remaining 22-oc gasoline was used from 1845 GMT , switching to container was possibly the reason why no radio call was given at cue ; it being also possible that crew was busy trying to receive bearing result that was asked for @ 1815 GMT . Air resistance , btw , is for land vehicles same as for aircraft : the labour needed is Pa = 1/2 R . Cw . A . V^3 with Pa = air resistance x way ; R = air density ; Cw = resistance coefficient ; V = speed . If measured in S.I. , outcome is in dimension Newton x m/s = Watts . The Johnson reports have for the inquiry not been used , other than for gph figures predicted ; remaining figures come from meteo versus true weather & radio calls . I am busy translating the 1996 articles , first on fuel loading @ Lae . H.
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So if there is somewhere between 50 and 100 gallons remaining once landed on Gardner is this enough for several days of running up the engine to charge radio batteries? I think i read something that said the engine had to be run at a setting higher than an idle to run the radio while charging the battery. Does the remaining fuel burned match the number of days of post loss radio messages?
Here is an interim report (http://tighar.org/wiki/Lockheed_Electra_10E_Special_-_NR16020#Battery_System) from Bob Brandenburg on that score.
Without doing the math, I think the answer is "yes."
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Here is an interim report (http://tighar.org/wiki/Lockheed_Electra_10E_Special_-_NR16020#Battery_System) from Bob Brandenburg on that score.
Marty,
Bob might want to correct the opening words of the seventh paragraph: "The transmitter high-voltage power supply was a dynamotor that drew 65 amps at 12 volts. . ." As he correctly indicates further on, it was the transmitter that drew approximately 65 A at 12 V under modulated conditions--not the dynamotor alone.
Chuck
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Here is an interim report (http://tighar.org/wiki/Lockheed_Electra_10E_Special_-_NR16020#Battery_System) from Bob Brandenburg on that score.
Bob might want to correct the opening words of the seventh paragraph: "The transmitter high-voltage power supply was a dynamotor that drew 65 amps at 12 volts. . ." As he correctly indicates further on, it was the transmitter that drew approximately 65 A at 12 V under modulated conditions--not the dynamotor alone.
Yes, I see. For the moment, I've amended the sentence to: "The transmitter drew 65 amps at 12 volts from a dynamotor, and thus could function at virtually full output even with the battery approaching zero charge."
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For the moment, I've amended the sentence to: "The transmitter drew 65 amps at 12 volts from a dynamotor, and thus could function at virtually full output even with the battery approaching zero charge."
Marty,
The transmitter drew 65 A at 12 V from a battery source, not from the dynamotor. Deleting "from a dynamotor" would fix your amended sentence.
Chuck
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Not to put too fine a point on it, but we should be careful about how we treat Brandenburg's statement - the transmitter only draws from the battery if you consider the dynamotor to be one and the same with the transmitter device. It was not.
Jeff,
Let's do put a finer point on it.
You wrote: ". . .the transmitter only draws from the battery if you consider the dynamotor to be one and the same with the transmitter device." That is not a true statement.
The dynamotor was not the only 12-volt transmitter-related load. The tube filaments were heated directly by 12 volts (~6 A standby, 10-11 A transmit). The oscillator crystal heater option, if used, operated on 12 volts. I think the control circuits were 12-volt, as well. It was the total of these loads, when transmitting, that equaled approximately 65 A.
Chuck
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For the moment, I've amended the sentence to: "The transmitter drew 65 amps at 12 volts from a dynamotor, and thus could function at virtually full output even with the battery approaching zero charge."
The transmitter drew 65 A at 12 V from a battery source, not from the dynamotor. Deleting "from a dynamotor" would fix your amended sentence.
I thought the dynamotor was an essential part of the operation--isn't the current going through it from the batteries through the dynamotor to the TX?
After further review, the offending sentence now begins, "The transmission system drew 65 amps at 12 volts, ..." I've dropped a box in the middle of the passage (http://tighar.org/wiki/Lockheed_Electra_10E_Special_-_NR16020#Battery_System) that gives more details about the dynamotor, the heating circuits, and the different operating modes.
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I thought the dynamotor was an essential part of the operation--isn't the current going through it from the batteries through the dynamotor to the TX?
Marty,
You're correct. The dynamotor was an essential part of the operation--and the first three sentences in your added box summarize the situation nicely. I've apparently done a grand job of unintentional obfuscation here, but all I wanted to point out was that it was all the 12-volt transmitter-related loads--including the dynamotor--that summed to 65 A, not just the dynamotor, as Bob stated it.
It's with great trepidation that I make another comment to the same writeup. In the sentence before the one under discussion, Bob wrote "Aircraft lead-acid battery cells of the period had a specific gravity range of 1300 at full charge to 1110 at fully discharged, with corresponding voltage range of 12.86 volts to 11.81 volts." The specific gravities should be 1.300 and 1.100, not 1300 and 1100.
Chuck
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It's with great trepidation that I make another comment to the same writeup. In the sentence before the one under discussion, Bob wrote "Aircraft lead-acid battery cells of the period had a specific gravity range of 1300 at full charge to 1110 at fully discharged, with corresponding voltage range of 12.86 volts to 11.81 volts." The specific gravities should be 1.300 and 1.100, not 1300 and 1100.
Corrected. I kept the last digit of the discharged state (1110 became 1.11), just in case the measurement is that accurate. Specific gravity is new by me.
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But in deference to putting a finer point on the whole equation, the transmitter standby circuitry (including relays, tube warming, etc.) was powered by 12 volts directly from the batteries; when the transmitter was activated, it was powered by 1050 volts from the dynamotor, which was first powered by 12 volts from the batteries.
OK. I've modified the table in the article (http://tighar.org/wiki/Lockheed_Electra_10E_Special_-_NR16020#Battery_System) to include this description. Rather than trying to work it into the quotation from Bob's original research paper, I've just let it stand alone at the end of the table as a summary of the situation.
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But in deference to putting a finer point on the whole equation, the transmitter standby circuitry (including relays, tube warming, etc.) was powered by 12 volts directly from the batteries; when the transmitter was activated, it was powered by 1050 volts from the dynamotor, which was first powered by 12 volts from the batteries.
OK. I've modified the table in the article (http://tighar.org/wiki/Lockheed_Electra_10E_Special_-_NR16020#Battery_System) to include this description. Rather than trying to work it into the quotation from Bob's original research paper, I've just let it stand alone at the end of the table as a summary of the situation.
Marty,
Unfortunately, that change to the table prompts two further comments:
1) Change the attribution for the first part from Bob Brandenburg to Mike Everette.
2) Delete the Jeffrey Neville entry. The transmitter was not powered by 1050 volts, per se. The transmitter received 1050 volts (at pins 13 and 16) from the dynamotor when it was activated for transmitting. This voltage was applied to the plates of the three tubes comprising the 1st and 2nd RF amplifiers. It was dropped across series resistors R10.1 and R10.2 to 380 V and applied to the plates of the oscillator and audio amplifier tubes (one each). That's all that 1050 volts was used for.
The transmitter received 12 volts from the battery for the tube filaments (pins 3 and 4 for +12 V and pins 1 and 2 for -12 V, or ground)--regardless of whether the transmitter was in standby (in which case it drew ~ 6 A), or in transmit (for which the average draw was 10.6 A). The transmitter received 12 volts from the battery on pin 5 for relays S4, S5, and S6, and for the oscillator crystal heaters if they were employed. Again, for both standby and transmit.
Chuck
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1) Change the attribution for the first part from Bob Brandenburg to Mike Everette.
OK.
2) Delete the Jeffrey Neville entry. The transmitter was not powered by 1050 volts, per se. The transmitter received 1050 volts (at pins 13 and 16) from the dynamotor when it was activated for transmitting. This voltage was applied to the plates of the three tubes comprising the 1st and 2nd RF amplifiers. It was dropped across series resistors R10.1 and R10.2 to 380 V and applied to the plates of the oscillator and audio amplifier tubes (one each). That's all that 1050 volts was used for.
The transmitter received 12 volts from the battery for the tube filaments (pins 3 and 4 for +12 V and pins 1 and 2 for -12 V, or ground)--regardless of whether the transmitter was in Standby (in which case it drew ~ 6 A), or in Transmit (for which the average draw was 10.6 A). The transmitter received 12 volts from the battery on pin 5 for the oscillator crystal heaters, if they were employed. Again, for both Standby and Transmit. The control voltage applied at pin 7 for the relay coils was likely to have been 12 volts from the battery as well, but I have nothing that explicitly states that. In any case, that too would be supplied in both Standby and Transmit modes.
I've added your new wrinkle to the table in the article (http://tighar.org/smf/../wiki/Lockheed_Electra_10E_Special_-_NR16020#Battery_System).
The more times I read Bob's battery epistle, the more things I find wrong. In this sentence he added 1, 6, and 2 and came up with 8:
"We assume an ambient current load of 8 amps during each signal block: radio receiver on (1 amp), transmitter in standby (6 amps for vacuum tube filaments), and the cockpit instrument lights (2 amps)."
We'll have to wait for Bob to tell us which number is in error (8, 6, or 2).
Let the one among us who has never made a miscalculation throw the first stone. :-\
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Let the one among us who has never made a miscalculation throw the first stone. :-\
I agree, Marty. I logged in to delete that final comment as unduly picky, but, alas, too late.
Chuck
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... I logged in to delete that final comment as unduly picky, but, alas, too late.
It's OK. There are cases where "two heads are better than one." I think this is one of them. :)
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For that reason, again, I suggest Mr. Varney or any others who wish to correct or challenge contact Bob directly with any critique - that would preserve authorship where deserved and be far more productive.
You mean something like this (http://tighar.org/smf/index.php/topic,418.0.html), perhaps?
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Marty, please just delete the entry you attributed to me - it is not in error but obviously it is not going to be easily understood as I'd intended. It only adds obfuscation to the points already well made by Brandenburg and Everette.
OK.
I also disagree with adding the tedium of transmitting circuitry to this topic on 'fuel consumption', but so be it if others believe it contributes here.
Well, I'm interested in having a relatively accurate description on the wiki of how things were designed to work in the aircraft. Thread drift happens. "Fuel consumption" is not only about the fuel consumed en route but also about fuel available to power the transmitter for the post-loss messages; the power requirement for the transmission is linked to the fuel available to recharge the batteries and/or contribute to transmission time.
I'll also note again that the more important point of this topic really seems to be whether AE and FN could have had the fuel to make it to Howland area, thence Niku, thence able to support a number of transmissions from that place. The rational answer seems to be "YES"; the aggregate message from Messrs. Brandenburg and Everette, despite minor errors, seems to support that reliably.
Agreed. It seems to me that the post-loss radio receptions can't be ruled beyond the bounds of possibility on the basis of the power consumption of the radio system.
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Fuel expenditure was not excessively high , if you would like to see the concerning computation (updated from 1996) , communicate an email address to hac.vanasten@gmail.com for a transcription (from dutch) of the final results .
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To go back to the question of knowing how much fuel they were using.
Each time they had to switch tanks they would have know how long it had taken to use whatever was in it, so they had several checks of how much fuel they had left, and how fast they were using it.
Richard Cooke
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To go back to the question of knowing how much fuel they were using.
Each time they had to switch tanks they would have know how long it had taken to use whatever was in it, so they had several checks of how much fuel they had left, and how fast they were using it.
Richard Cooke
Good point.
Unfortunately this topic got beaten into the weeds over how much fuel may have been used for the transmission attempts and I believe we lost the more important big picture. How many ounces were burned making "juice" for the radios is incidental compared to how many gallons may have been left to get NR16020 to Gardner, and thence to run all the iron needed (engine + generator) to run the radio after missing Howland.
But I think the abundant evidence on this site affirms the spirit of your observation - fuel management was accounted for in the 'plan' and it is reasonable to believe AE had a rational grip on that aspect of flight management given the information and tools she had in-hand. Switching tanks by a schedule would indicate some notion of how much was consumed per tank before moving to the next, etc.
LTM -
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N.B.: My apologies to the original author, Irvine John Donald. I had intended to Quote his post, but Modified it instead. My bad. :P
... Her radio message said they were running north and south.
Her last transmission (http://tighar.org/smf/../wiki/Last_transmission) also indicated that she was switching to her "daytime frequency."
You (and many others) seem not to understand the problems with AE's antennas (http://tighar.org/smf/../wiki/Antennas) along with the generic difficulty any day of the week of radio propagation. (http://tighar.org/smf/../wiki/Propagation)
Your assumption is that changing frequencies would have made no difference with propagation and reception of her transmissions.
I believe that that assumption is unwarranted. The Coast Guard tried to get her to stay on 3105 kcs because they were receiving those transmissions without difficulty. They knew from experience that some frequencies propagate less well than others.
Why wouldn't she have been talking the whole time?
I imagine that she was talking the whole time, more or less.
I also imagine that there was something about her antennas and that time of day that kept her transmissions from being heard.
The radio operators said they thought her voice sounded more anxious on some of the last transmissions.
People see what they want to see and hear what they want to hear. AE had been advised in Lae to "pitch her voice higher" (http://tighar.org/smf/../wiki/Failed_direction_finding_test_in_Lae) when transmitting in order to improve the intelligibility of her transmissions. It is conceivable that she was acting on this advice.
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Thanks Marty
All good points. Switching frequencies and antenna issues means she could have been talking the whole time and nobody receiving. I think I can live with that explanation.
When transmitting the post loss messages she was back on 3105 kcs and was heard so it very likely was the frequency and antenna issue.
Okay so now we believe she had the fuel to get to Gardiner and run her engine to transmit. Credible sources heard her. Now why wasn't Gardiner identified in the radio messages? Perhaps time for a new thread.