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Author Topic: Modeling fuel consumption using Lockheed 487 Report.  (Read 27969 times)

Heath Smith

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Modeling fuel consumption using Lockheed 487 Report.
« on: February 24, 2012, 02:57:29 PM »

Is anyone out there interested in creating fuel consumption models based on the 487 Report?

I read over the Montaro Product Development Services model of the performance of the Electra 10E and I am wondering if there is not a simple model that could be used based on the flight data from page 33 of the 487 report?

Has anyone spent effort on this?

Thanks.

« Last Edit: February 25, 2012, 06:39:38 AM by Heath Smith »
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Heath Smith

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #1 on: February 25, 2012, 02:18:50 PM »

Here is a chart that shows the curve fitting for the data from page 33. These same curves are shown on page 10 of the Lockheed report. The page 10 values are all assuming sea level (S.L.). To determine a fuel consumption for any weight and speed, a simple linear interpolation can be used to give you the GPH. It should then be a matter of adjusting for increased efficiency at altitude as shown at the lower half of page 15. This should be a fairly close estimate as I believe that data is based on actual flight data rather than a theoretical model.
« Last Edit: July 18, 2012, 03:56:33 AM by Heath Smith »
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Ted G Campbell

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #2 on: February 25, 2012, 06:59:07 PM »

For the navigation, radio and fuel consumption gurus out there.  Can we pin down an area where AE and FN may have been when AE transmitted “we must be on you but we can not see you”?

My suggestion is to work backward from the TIGHAR hypothesis that they ended up on Niku.

How?

1.   Draw a series of S5 signal strength circles around Howland Is. i.e. this gives us a probable point of entry into the intended landing destination.
2.   Draw a series of parallel 337-157 lines that are “visual distant apart at 1000 feet altitude”.  These lines will be drawn to the East and West of Niku (remember we are assuming that TIGHAR’s hypothesis is that they landed on Niku).
3.   Draw a line perpendicular to the 337-157 line that is “4 hr. max fuel consumption” North of Niku (see TIGHAR’s note in 2 above)
4.   Draw a series of lines perpendicular to the 337-157 lines suggested in 2 above i.e. at “1000 foot visual range” South and North of Howland.  Remember they did not see Howland.
5.   Draw a series of lines perpendicular to the 337-157 lines North and South of Baker Is.  Obviously they didn’t see Baker either or they would have known how to navigate between the two islands i.e. Baker and Howland.

Within these series of circles and parallel lines can we shade in an area of high probability of the flight path entry into the Howland Is. area?  If so does this lessen or strengthen either the “crash and sank” or the TIGHAR hypothesis?
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Monty Fowler

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #3 on: February 27, 2012, 09:56:20 AM »

Well ... except that "signal strenth" was a relative as opposed to a literal term, i.e., one person's S3 was another person's S4 or S5 ... it depended on the operator's interpretation of what he/she was hearing at that particular moment in time. Regardless of what the reference books or training said.

LTM,

Monty Fowler, TIGHAR No. 2189 CER
Ex-TIGHAR member No. 2189 E C R SP, 1998-2016
 
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Heath Smith

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #4 on: February 27, 2012, 04:51:42 PM »


Here is a chart from the Waitt Institute Reconstruction Report that shows estimates for the distance versus reported signal strength. As you say this is subjective and pretty course but might help give you are fair radius.
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Ted G Campbell

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #5 on: February 27, 2012, 08:36:33 PM »

OK, let's use this as starting point.  Let's put together a graph of how this all may come together!
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Gary LaPook

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #6 on: March 29, 2012, 01:43:04 AM »

Is anyone out there interested in creating fuel consumption models based on the 487 Report?

I read over the Montaro Product Development Services model of the performance of the Electra 10E and I am wondering if there is not a simple model that could be used based on the flight data from page 33 of the 487 report?

Has anyone spent effort on this?

Thanks.
Has anyone noticed a glaring error on page 12-13 of the Montaro report

gl
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Heath Smith

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #7 on: March 29, 2012, 03:41:25 AM »

Two curves are presented, one yielding 4100 mile range, the other 4500. These seem to represent conservative and optimal estimates of achievable engine efficiency?
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Gary LaPook

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #8 on: March 29, 2012, 05:23:07 AM »

Two curves are presented, one yielding 4100 mile range, the other 4500. These seem to represent conservative and optimal estimates of achievable engine efficiency?
No, that's not it.

gl
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Erik

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #9 on: March 29, 2012, 11:26:37 AM »

I'll try...  Is this it?

Complete data on the fuel consumption of the engine was not available so generalized data on
aircooled engines
was used.


Or not, can I take a Mulligan.... : )

The state vector used by our model consists of five components: distance (d), ground speed ( ),
altitude (h), regular octane fuel load ( ) and high octane fuel load ( ).
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Randy Reid

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #10 on: March 29, 2012, 01:17:34 PM »

Gary, I might as well take a shot: isn't the specific fuel consumption chart a little backwards? shouldn't the pounds per hp increase from left to right instead of right to left? most of the recip engines I know about use more fuel as the hp and load increases.
or are you looking at one of the formulas that I cannot understand anyway?
go ahead and laugh, I admit to not being the sharpest tool. ;D
Randy
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Heath Smith

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #11 on: March 29, 2012, 03:15:47 PM »

"These curves only cover the power range from 200 to 350 Horsepower. But other areas of the report describe operating conditions of up to 400 BHP in normal flight and 600 BHP during takeoff."

Because they are confusing the output of a single engine with the charts that assume the combined horse power?
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Randy Reid

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #12 on: March 29, 2012, 06:31:25 PM »

Quote
Gary, I might as well take a shot: isn't the specific fuel consumption chart a little backwards? shouldn't the pounds per hp increase from left to right instead of right to left?
I retract my wag, after I played with the figures a little, it started to make sense. so I am going to keep looking for the "glaring error". This sure beats working the crossword puzzles.
Randy
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Gary LaPook

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #13 on: March 30, 2012, 01:45:04 AM »

Quote
Gary, I might as well take a shot: isn't the specific fuel consumption chart a little backwards? shouldn't the pounds per hp increase from left to right instead of right to left?
I retract my wag, after I played with the figures a little, it started to make sense. so I am going to keep looking for the "glaring error". This sure beats working the crossword puzzles.
Randy
You should have quit while you were ahead, you got it right in you previous post. The Mantaro report on page 12 states they are extrapolating by "keeping efficiency constant above 350 BHP" and this is shown on their graph on page 13 by extrapolating the BSFC straight up. Anybody who has ever flown an airplane knows that this is wrong! Above 65% power on P&W round engines (above 400 BHP on Earhart's 600 BHP engines) requires a "full rich" mixture to prevent damage to the engines. Using "full rich" causes the BSFC to increase greatly. This calls into question the rest of the Mantaro report.


The Pratt and Whitney power setting table for Earhart's P&W S3H1 engines is attached.

According to Pratt and Whitney this engine burns 65 gallons per hour at full 600 hp power output making the BSFC .65, 130 gallons per hour total for two engines. Running the engines at full power would have used up the 1100 gallons on board in 8:28.


Running the engines at 550 hp burns 55 gallons per hour making the BSFC .60 and
burning all the 1100 gallons in 10:00

Contrary to Lockheed report 487 and other documents that state the BSFC of .42, the best BSFC obtained according to this Pratt and Whitney table (the people who manufactured the engines) is .48 and this was at 300 and 350 hp. Cruising with 350 hp per engine burns 28 gallons per hour per engine which would have used 1100 gallons in 19:38. Cruising with 300 hp per engine uses the 1100 gallons in 22:56.

The lowest fuel flow stated is 21 gallons per hour per engine for 250 BHP (BSFC of .50) so it appears that Earhart's statement on the Hawaii flight that they were burning 20 gallons per hour was referring to the fuel flow to each engine making the total fuel flow about 40 gallons per hour. At 21 gallons per hour per engine the 1100 gallons would have produced an endurance 26:11. (But higher power settings had to be used early in the flight.)

So Mantaro's extrapolation is completely wrong and the graph, instead of going straight up, should bend sharply to the left.

I have also attached page 33 from report 487 and you can see that these BSFC values are optimistic compared to the P&W document.

gl
« Last Edit: June 09, 2013, 01:58:19 AM by Gary LaPook »
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Randy Reid

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Re: Modeling fuel consumption using Lockheed 487 Report.
« Reply #14 on: March 30, 2012, 11:34:10 AM »

Gary, I agree. I would have thought the plots would run the other direction, from lower right to upper left. All the piston engines I have any experience with use the least fuel just off idle. At any higher rpm, all bets are off, too many variables. Of course, the least fuel used is when the engine is off. ;D
Randy
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