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Author Topic: Fuel System Research Bulletin  (Read 36172 times)

Ric Gillespie

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Fuel System Research Bulletin
« on: November 02, 2011, 12:48:29 PM »

A new Research Bulletin describing the evolution of the fuel system aboard NR16020is now up on the TIGHAR website.  Click on the link here
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Martin X. Moleski, SJ

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Re: Fuel System Research Bulletin
« Reply #1 on: November 02, 2011, 02:00:46 PM »

A new Research Bulletin describing the evolution of the fuel system aboard NR16020is now up on the TIGHAR website.  Click on the link here

There seems to be a small discrepancy in the drawings.

Fuselage tank #5 in one drawing is shown as 70 gallons.

On the "rear floor valve" fuel selector gauge in the same drawing, fuselage fuel tank #5 is reported as 149 gallons.




LTM,

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Gary LaPook

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Re: Fuel System Research Bulletin
« Reply #2 on: November 02, 2011, 02:22:03 PM »

A new Research Bulletin describing the evolution of the fuel system aboard NR16020is now up on the TIGHAR website.  Click on the link here
-----------------
These are my two posts of today and yesterday on the "Mystery rods" thread that describe the use of the fuel system.

Contrary to modern twin engined planes the Electra had a fuel system that fed both engines from the same tank. The right valve under the throttles is a standard Electra valve, with "right engine on," "left engine on," "both engines on ," and "both engines off" positions choosing which engine is to receive fuel from the fuel system. The left valve is in series with the right valve and is also almost standard, it selects the fuel tank to use, "right 97 gal. wing tank,"  "left  97 gal wing tank," "right 102 gal wing tank," "left 102 gal wing fuel tank," "off," and then the added position of "fuselage tanks." When in the "fuselage tanks" position it then opens the port to a third valve that selects which of the fuselage tanks to use. If it was desired to use fuel from one of the two forward 118 gallon tanks then the third valve was turned to "off" and fourth valve was opened to chose "right" or "left."

The above description is quite straight forward and should not confuse anybody.

Now looking at the rest of the fuel plumbing diagram in the Electra we come to the confusing part. There are two additional valves, the first labeled "stripping valve" and the one just below it on the diagram labeled "...RD," the rest of the label that is cut off is "forward floor valve." This valve duplicates the left valve on the instrument panel (this is the upper left valve on the diagram that is cut off) and both of these valves are connected in parallel allowing selecting any of the fuel tanks. This second valve is used to transfer fuel INTO a selected fuel tank. The valve on the instrument panel selects the tank that fuel is drawn OUT OF to go to the engines. The forward floor valve is connected to the stripping valve and the stripping valve selects where the fuel to be transferred comes from, either from the wobble pump or from the tank selected for supplying fuel to the engine.

Two examples will make this clear. Let's say all the fuel from the number 5 fuselage tank has been used up. Earhart then switches the left fuel selector valve away from the "fuselage" position to one of the wing tank positions to keep the engines running. She then sets the stripping valve to the wobble pump position and sets the forward floor valve to one of the wing tanks positions and then pumps the handle to move the remaining fuel from the depleted fuselage tank into the selected wing tank. After this is completed she then sets both of these valves back to off. (Note, only fuel from the fuselage tanks can be moved with the wobble pump and it can only be sent to a wing tank. Also, the plane must be using a wing tank during this operation, not one of the fuselage tanks. )





gl
« Last Edit: August 15, 2012, 11:24:24 PM by Gary LaPook »
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Chuck Varney

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Re: Fuel System Research Bulletin
« Reply #3 on: November 02, 2011, 03:46:01 PM »


There seems to be a small discrepancy in the drawings.

Fuselage tank #5 in one drawing is shown as 70 gallons.

On the "rear floor valve" fuel selector gauge in the same drawing, fuselage fuel tank #5 is reported as 149 gallons.

Marty,

The discrepancy originated with Lockheed. See the blueprint in the Purdue collection, where the #5 FUSELAGE 149 GAL switch sector is shown linked to the tank labeled #5 FUSELAGE 70 GAL.

Chuck
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Martin X. Moleski, SJ

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Re: Fuel System Research Bulletin
« Reply #4 on: November 02, 2011, 04:22:19 PM »


There seems to be a small discrepancy in the drawings.

Fuselage tank #5 in one drawing is shown as 70 gallons.

On the "rear floor valve" fuel selector gauge in the same drawing, fuselage fuel tank #5 is reported as 149 gallons.

The discrepancy originated with Lockheed. See the blueprint in the Purdue collection, where the #5 FUSELAGE 149 GAL switch sector is shown linked to the tank labeled #5 FUSELAGE 70 GAL.

Thanks for confirming that the discrepancy is in the original drawings.

I couldn't see it clearly in the image that shows the tank as 70 gallons--the label for the tank is clear, but the drawing of the valve was a little too fuzzy for me to be sure that it read "149 gallons."
LTM,

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John Ousterhout

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Re: Fuel System Research Bulletin
« Reply #5 on: November 03, 2011, 06:35:41 AM »

I was searching on the web for any details of 1937 dump valves and stumbled upon this interesting article about the new Electra as a British passenger airliner.  It includes a nicely detailed drawing of the cockpit, which includes a reference to the fuel dump valve handle, located next to the pilots' seat, but does not show what it looked like or describe it in any detail.
http://www.flightglobal.com/pdfarchive/view/1937/1937%20-%201026.html

Cheers,
JohnO
 
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Ric Gillespie

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Re: Fuel System Research Bulletin
« Reply #6 on: November 03, 2011, 06:44:01 AM »

It includes a nicely detailed drawing of the cockpit, which includes a reference to the fuel dump valve handle, located next to the pilots' seat, but does not show what it looked like or describe it in any detail.

The cockpit in the article is, of course, quite different from Earhart's with respect to instruments and their location, but the basic controls are the same.
The reference to the fuel dump confirms that even the standard airplane had that capability.  Earhart's Electra, BTW, did not have de-icer boots.
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John Ousterhout

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Re: Fuel System Research Bulletin
« Reply #7 on: November 03, 2011, 07:57:49 AM »

gl comments: "...(The wobble pump is operated with the lever with the white handle sticking up from the floor in front of the fuel selector valves and is shown just to the right of Earhart's knee in this photo.)..."

This creates another discrepancy - according to the drawing in the www.flightglobal.com archive I linked to earlier, that lever is the brake control.  Is the "emergency fuel pump" in the drawing the same as the wobble pump?  If so, then it's the black handle to the right of the throttles.  'Seems rather awkward to me.

Cheers,
JohnO
 
« Last Edit: November 03, 2011, 08:02:46 AM by John Ousterhout »
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Ric Gillespie

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Re: Fuel System Research Bulletin
« Reply #8 on: November 03, 2011, 10:23:04 AM »

The big handle (aka "Johnson Bar") in the middle is the brake, sometimes called the "emergency brake."  The Lockheed 10 Operating Manual says:

"Operation of brakes: Differential action is obtained by pressure on either right or left rudder toe brake pedal after the emergency brake has been pulled back about 3 notches."
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John Ousterhout

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Re: Fuel System Research Bulletin
« Reply #9 on: November 04, 2011, 06:49:38 AM »

Gary,  please clarify something for me - the hand pump pushes fuel towards a Tee which splits it towards the Stripping Valve and towards the Engine Selector Valve. When you say "... the hand pump cannot be used as an emergency pump", and "that surprises me", you seem to imply expectation of some other arrangement.  Are you surprised that the fuel route to the Stripping Valve cannot be blocked, so the Hand Pump would force fuel towards the Engine Selector Valve?  As it appears, the best it could do is to present fuel to the Engine Selector Valve at near zero pressure.  I am ignorant of the fuel pump and carburetor arrangement on the engines, so I cannot offer any opinion of the effectiveness of this arrangement.  Do they have mechanical fuel pumps like on an old automobile engine? In normal conditions, how do the engines draw fuel from the Engine Selector Valve, and how would an "emergency pump" help?
Cheers,
JohnO
 
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Gary LaPook

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Re: Fuel System Research Bulletin
« Reply #10 on: November 04, 2011, 08:23:04 AM »

Gary,  please clarify something for me - the hand pump pushes fuel towards a Tee which splits it towards the Stripping Valve and towards the Engine Selector Valve. When you say "... the hand pump cannot be used as an emergency pump", and "that surprises me", you seem to imply expectation of some other arrangement.  Are you surprised that the fuel route to the Stripping Valve cannot be blocked, so the Hand Pump would force fuel towards the Engine Selector Valve?  As it appears, the best it could do is to present fuel to the Engine Selector Valve at near zero pressure.  I am ignorant of the fuel pump and carburetor arrangement on the engines, so I cannot offer any opinion of the effectiveness of this arrangement.  Do they have mechanical fuel pumps like on an old automobile engine? In normal conditions, how do the engines draw fuel from the Engine Selector Valve, and how would an "emergency pump" help?
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I see where I went wrong. I was looking at the fuel system blue print here:
http://earchives.lib.purdue.edu/cdm4/item_viewer.php?CISOROOT=/earhart&CISOPTR=3683&CISOBOX=1&REC=8

and the "hand" was cut off from "fuel pump" so I thought that this was a mechanical or electrical pump. Now that I have looked at the drawing I see that it is the standard hand pump which is used, according to the Electra operating manual, for pumping up pressure for starting the engines and, probably for emergencies. (I say "probably" because we don't know the capacity of that hand pump and whether it can supply fuel at a rate sufficient to keep an engine running nor does the Electra manual mention using in for emergencies.)

Looking further, I looked at my Wasp maintenance manual and it shows that each engine has its own engine driven mechanical pump, see attached scan (the S3H2 engine shown is the same as Earhart's S3H1 except that there is an angled adapter block for mounting the carburetor so that the carb remains horizontal while the engine is mounted at an angle for use in a helicopter), so the line between the hand pump and the engines would be under suction, not pressure so this changes my analysis.

Looking at the stripping valve, placing it in the "standard" position would allow the engines to draw fuel through the "forward floor valve" from any tank at the same time the engines were drawing fuel through the "control stand selector valve" although I don't see any reason to have this capability or reason to do it. So this position could not be used to transfer fuel between tanks.

Placing the "stripping valve" in the "wobble pump" position allows the wobble pump to "strip" any remaining fuel from the fuselage tanks and move it to the wing tanks. The "T" junction you pointed to is in the supply side of the wobble pump plumbing so the fuel moves in the opposite direction than you were thinking. After all, that is the purpose of the "stripping" system.

So, a separate wobble pump was added to the plane so it was not operated with the "hand fuel pump" handle on the right side of the panel as I had thought but the wobble pump handle does not appear to be shown in any of the photos either.

gl
« Last Edit: November 04, 2011, 08:49:43 AM by Gary LaPook »
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Gary LaPook

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Re: Fuel System Research Bulletin
« Reply #11 on: November 04, 2011, 08:33:12 AM »

I was searching on the web for any details of 1937 dump valves and stumbled upon this interesting article about the new Electra as a British passenger airliner.  It includes a nicely detailed drawing of the cockpit, which includes a reference to the fuel dump valve handle, located next to the pilots' seat, but does not show what it looked like or describe it in any detail.
http://www.flightglobal.com/pdfarchive/view/1937/1937%20-%201026.html
---------------------------
Fuel dump valves were standard on the Electra and were "T" pull handles located on the floor under the pilot's seat. To operate them the pilot pulled them up which opened a dump valve in the chosen wing tank. Once opened they could not be closed and all the fuel from that tank would be dumped. Since this is, obviously, a critical operation, the handles were "safetied" so that they could not be inadvertently pulled. The reason for dumping fuel was for dealing with the loss of an engine since the plane might not be able to maintain altitude on one engine without losing weight.

gl
« Last Edit: November 04, 2011, 08:39:44 AM by Martin X. Moleski, SJ »
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John Ousterhout

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Re: Fuel System Research Bulletin
« Reply #12 on: November 04, 2011, 08:42:12 AM »

Gary, thanks for the clarification.  You're a great resource.
Regarding the standard Electra dump valves, do you have any idea if the handles might have been the same as the ones on the ends of the mystery rods?
Cheers,
JohnO
 
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Gary LaPook

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Re: Fuel System Research Bulletin
« Reply #13 on: November 04, 2011, 09:36:10 AM »

Gary, thanks for the clarification.  You're a great resource.
Regarding the standard Electra dump valves, do you have any idea if the handles might have been the same as the ones on the ends of the mystery rods?
--------------
Hmmmm, interesting. I would suspect not since I believe the dump valves were activated by pull cables, not rigid rods.
gl
« Last Edit: November 04, 2011, 09:38:51 AM by Gary LaPook »
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Chris Johnson

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Re: Fuel System Research Bulletin
« Reply #14 on: November 04, 2011, 10:01:36 AM »

Gary, thanks for the clarification.  You're a great resource.
Regarding the standard Electra dump valves, do you have any idea if the handles might have been the same as the ones on the ends of the mystery rods?
--------------
Hmmmm, interesting. I would suspect not since I believe the dump valves were activated by pull cables, not rigid rods.
gl

Could they have replaced the cables with the rods to prevent accidental dumping if the cable was snagged?

My thinking is that if people had to climb over the tanks to get from the cockpit to the rear of the plane wire cables might easily be caught by someone scrambling.
« Last Edit: November 04, 2011, 12:40:31 PM by Chris Johnson »
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