TIGHAR
Amelia Earhart Search Forum => General discussion => Topic started by: Ric Gillespie on October 19, 2016, 10:57:15 AM
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As we saw in our discussions about the events surrounding the delivery and testing of the Electra in July and August 1936, there was an apparent problem with the seven fuselage tanks which resulted in their removal on July 28, the day after July 27 when Earhart applied (unsuccessfully) for "NR" registration. The tanks were still out on August 7 when the airplane was inspected for its "R" registration. The application for the "R" registration listed a total fuel capacity of only 394 gallons because the fuselage tanks had been removed. The problem, whatever it was, was resolved and the fuselage tanks were re-installed, presumably sometime before August 29 when Earhart left for New York to participate in the Bendix race.
While the airplane was at Purdue in October, Bo McKneeley noticed that the R16020 license only approved the airplane for 394 gallons. Thinking it was a clerical error, Putnam complained to the Bureau of Air Commerce but they responded that the 394 gallons was correct according to the paperwork. To correct the license, the airplane had to be inspected again. On November 27, 1936 it was inspected at Garden City, Long Island, NY. Now there were only six fuselage tanks. To the question, "Has the airplane been altered or repaired since last inspection?" the answer was "Yes." By whom? "Lockheed Aircraft Corporation" When? "July 28, 1936" Describe details
of repairs or alterations. "7 fuselage tanks removed as shown in Item 25. False floor installed" Item 25 lists the weight of the removed tanks and flooring. No mention of when the tanks went back in.
I'm curious about the nature of the problem because we have long hypothesized that artifacts we found on Niku are "heat shields" that were were installed between the cabin heating ducts and the fuselage tanks to prevent vapor lock caused by heating of the tanks if the cabin heating system was on. see https://tighar.org/Projects/Earhart/Archives/Research/Bulletins/51_HeatShields/51_DetectiveStory.html
As we know from McLeod's logbook, he made several test flights in the airplane prior to delivery on July 24. That may have been the first time the plane was taken to an altitude where cabin heat was needed. Maybe the problem showed up then. The next day, July 25, McLeod made a one-hour, 200 mile, Burbank to Burbank test flight which must have confirmed the problem. He logged no further flights in X16020 before the tanks came out on July 28.
So what is a "false floor?" And what problem could its installation fix?
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So what is a "false floor?"
Sorry for the low-res photo but I think it will show up.....what is that under the fuel tanks? It appears to be a separate layer of "something", not part of the observable exterior of the tanks themselves. Some sort of insulating or isolating layer or flooring material between the topside of the 10E's floor and the underside of the tanks?
Possible materials might include:
- Felt
- Cellulose fiberboard
- Asbestos fabric
And what problem could its installation fix?
- Insulating the tanks from cabin heat conducting through the floor from the cabin heat ducts (not radiating from the cabin heat duct directly)?
- Damping airframe vibration from being transmitted into the fuel tanks to reduce oscillating waves (not sloshing, more like buzzing) involving such large quantities of liquid?
Or am I up in the night?
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And what problem could its installation fix?
- Insulating the tanks from cabin heat conducting through the floor from the cabin heat ducts (not radiating from the cabin heat duct directly)?
The heater ducts ran along the base of the cabin wall. I don't see how heat would come up through the floor. Those tanks are bunged right up against the heater ducts. In the Alaska wreck (which had one fuel tank in the cabin) heavy asbestos felt had been fastened over the heater duct where the tank was. (See photo attached.) So we know that insulating the tanks from the ducts was necessary - perhaps a lesson learned from c/n 1055. . In the case of the Alaska plane it was just one small fuselage tank so the heavy asbestos was a reasonable solution, but to insulate NR16020 with asbestos would have meant a huge weight penalty. Little free-standing aluminum structures insulated with kapok would be more trouble to build but wouldn't add much weight.
[li$i]Damping airframe vibration from being transmitted into the fuel tanks to reduce oscillating waves (not sloshing, more like buzzing) involving such large quantities of liquid?[/li]
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Maybe, but the Alaska wreck confirms that protecting fuselage fuel tanks from the heater ducts was necessary.
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The heater ducts ran along the base of the cabin wall. I don't see how heat would come up through the floor.
I suppose I should ask for my own clarification: was the floor aluminum or wood? I can understand how the asbestos fabric would insulate well from radiated heat from the heater duct but if the floor was aluminum, then given the consideration that NR16020 would be flying for many more hours at a stretch than the Alaska Electra (and at altitude), would it be a reasonable concern to insulate the underside of the tank from heat conducted from the ductwork into the floor structure and from there back up into the tank, minimizing the effectiveness of the kapok-insulated aluminum panels? Throwing it out there for what it's worth, perhaps what we see in the photo are some sort of insulating "blankets" placed on top of the floor when the tanks were reinstalled?
Or maybe the "false flooring" refers to the decking placed on top of the tanks as seen in the attached photo?
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was the floor aluminum or wood?
The flooring in Electras was made of linoleum-covered plywood panels that could be removed for access to the supporting aluminum structures.
Or maybe the "false flooring" refers to the decking placed on top of the tanks as seen in the attached photo?
Perhaps, but it's hard to see how the installation of the decking would require the removal of the tanks.
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The flooring in Electras was made of linoleum-covered plywood panels that could be removed for access to the supporting aluminum structures.
That would address/eliminate the possibility of a the need of insulation from conducted heat...
Describe details of repairs or alterations. "7 fuselage tanks removed as shown in Item 25. False floor installed" Item 25 lists the weight of the removed tanks and flooring. No mention of when the tanks went back in.
Perhaps, but it's hard to see how the installation of the decking would require the removal of the tanks.
In that order, true.
Time to put the thinking cap back on....
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I'm wondering if the addition of two filler necks for the fuselage tanks might have been done as part of the rebuild of the fuel system that was going on in late July and early August:
https://tighar.org/Projects/Earhart/Archives/Research/Bulletins/61_FuelSystem/61_FuelSystem.htm (https://tighar.org/Projects/Earhart/Archives/Research/Bulletins/61_FuelSystem/61_FuelSystem.htm)
But even if so, I can't see any helpful connection with the hypothesis that heat shields were needed and added at that time, which is what we're after just now, because of those artifacts.
The Timeline for Aug 30 shows a Cleveland newsphoto of AE beside the Electra that shows 4 fuel ports, so the 2 new ports had already been added by then. See the Timeline, I can't get the photo to transfer.
"At Cleveland Municipal Airport, August [31] 1936. Note fuel ports. Source: Cleveland Plain Dealer Historical Archives (cleveland.com)"
In the excerpt from the movie Love on the Run, at 41 seconds, there appear to be only two fuel filler ports on the side of the fuselage, but then at 50 seconds all 4 are there, as we would expect: https://www.youtube.com/watch?v=7dvJFAlPdNM&feature=em-uploademail (https://www.youtube.com/watch?v=7dvJFAlPdNM&feature=em-uploademail)
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I'm wondering if the addition of two filler necks for the fuselage tanks might have been done as part of the rebuild of the fuel system that was going on in late July and early August:
I think you're right. The addition of two more fueling ports happened some time before the Love on the Run scene was filmed. The movie went into production on August 19. Purdue president Elliott arrived to see the new airplane the next day, August 20, so the scene for the film was shot sometime in the week between when Elliott left (August 21?) and August 29 when Earhart left for the east coast to participate in the Bendix race.
So the installation of additional fueling ports was part of the late July/early August change in the fuel system. We know that the tanks came out and something seems to have been done involving the floor ("false floor installed"). Apparently further work on the fuel system was needed. One of the tasks that McKneeley was supposed to accomplish while the airplane was at Purdue in October was to "cover the fuel lines" but that didn't get done until the plane was back in Burbank. See attached from the Doris Rich files at NASM. (Item 5 "hatch for refueling if that plan goes through" is in reference to Earhart's proposed inflight refueling.)
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I would think that the floor would be a "Cargo" floor due to the increased weight of the dense fuel tanks. All of the cargo and military derivative airplanes built in the great Northwest :) have the cargo flooring option which allows greater carrying capacity. Maybe this is some of the confusion regarding the floor.
Jim
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Was wondering if the reference to false flooring may be an additional layer of plywood material that Friend Weller pointed too in his image? It appears that a layer of flooring in place beneath Earhart's feet, is firmly fixed to substructures in the empty cabin image, attachments seem in place at points along the center seam line. The sheets beside Earhart in the empty cabin image may be the false floor, not yet in place. The foil lined image shows floor sheet goods running the opposite direction of the ( true) subfloor, or it seems so looking at the seam. Sometimes a false floor or chase is utilized so utilities ( electric/water/etc) can run beneath undisturbed, but in this case there appears no void between layers. A guess would be strengthening the floor under the tanks, as it seems that the false floor ends at the tanks, where Friend has his pointers.
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All really good observations. Great work gentlemen. Here's what I see.
The first photo below was taken on May 26, 1936 during construction of the aircraft. The flooring is standard Electra flooring. The heater ducts and fueling ports have not yet been installed. The plywood sheets off to the side are not the false flooring that was later installed. That didn't happen until after the airplane was delivered.
The second photo below is really interesting. It was obviously taken at the same time as the third photo below because the front of the Sperry Gyropilot is open in both photos. The false flooring has been installed because, as you guys have observed, the plywood now runs horizontally and has no metal edging. A rivet on the main beam is no longer visible because the false floor has been laid on top of the original floor. The purpose of the false floor is obvious - to beef up the floor to support the weight of the tanks. The work is still underway because the fueling ports have not yet been changed. This photo must have been taken sometime between July 28 (the earliest date for the removal of the tanks) and the week of August 21-28 (the filming of Love on the Run, the earliest photos showing the four fueling ports.
Of special interest (to me anyway) are the wooden strips on the false floor immediately adjacent to the heater ducts. Why are they there? The putative heat shields we found on Niku appear to have been free-standing structures that were nailed, not riveted, to an underlying surface., as shown in the fourth illustration below from https://tighar.org/Projects/Earhart/Archives/Research/Bulletins/51_HeatShields/51_DetectiveStory.html
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Interesting , that little wood strip,....will keep looking for more interior images. From a design standpoint, it seems a heat deflector (dado) constructed that way, would indeed help deflect heat from the bottom of the tanks , but doesn't seem that it would prevent heat from being redistributed along the entire sides of the tanks, via the small space between tanks and fuselage walls... ( a sort of duct-work if you will). If the problem was heating of fuel, I don't know that this would remedy the problem, as a rather large amount of tank surface would still receive heat from the cabin piping. Most shields I have experience with are wrap around or partially wrapped around the pipe and the ends are open to allow heat transfer out of the ends of the shield and out to safe areas. The remainder of the cabin piping to the cabin door was covered with aluminum shields it appears. It appears that the wood strip is too far away from the fuselage wall to involve any attaching of the wall board liner material too it. Does anyone know, for curiosity sake,how hot the cabin pipe got soon after passing through the manifold heater and into the cabin piping?
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One thought, is that little strip of wood for attaching an aluminum shield ( similar to the one aft of the tanks)?
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One thought, is that little strip of wood for attaching an aluminum shield ( similar to the one aft of the tanks)?
Those are not aluminum shields. Those are the actual heat ducts. There is no "hot pipe" inside. It's just ducting for hot air. The attached photo shows what the heating ducts looked like in the standard airline version. As you can see, there was a little grilled opening in the ducts beside each passenger.
The photo is cn 1026, a 10A in the Oakland Air Museum.
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Ingenious,....fabric that matches the wall panel to boot so it looks nice. Cut out grate holes where you want them.....wonder where Earhart placed her grills, as in the few photos I have, I can't see them. Some pondering on my part though, how does the fabric tube stay open, in case someone placed an object upon it, either unintentionally, or perhaps a child seated in back of the passenger in front of him, tires of kicking the backrest and decides to stand on the tube, causing a stoppage of heat flow to the passengers behind him/her trying to freeze them out, and in turn giving the passenger in front a concentrated heat blast?
On a more serious note; what continues the connection located between the heat ducts, where the flap actuator brackets and covers are located? In the photo it is hard to tell if there is a pipe connection running through the bracket , but it seems a hole is provided if it is the case. I don't see a tying of the ends of the fabric ducts around a pipe there, it would seem the transfer of heat between ducts might be interrupted if some transition piece wasn't installed there.I noted on the edited attachment that on the aft end of the Starboard duct, something seems sticking out of the duct, or maybe it is just wallboard material. I don't see the temperature of this type of ducting becoming all that hot, with such easy passenger access to it....maybe some 75-80 degrees?
As far as the piece of wood, I wonder why it would be necessary to use it to mount a dado atop, as there are already two multi-ply sheets of wood to attach it too.
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What continues the connection located between tubes, where the flap actuator brackets and cover are located?
As you can see from the photo below, the heater duct runs under the flap actuator covers.
As far as the piece of wood, I wonder why it would be necessary to use it to mount a dado atop, as there are already two multi-ply sheets of wood to attach it too.
So that you can remove the heat shields without removing the whole floor panel.
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I believe the flap actuator covers allow for the bulk and curvature of the fabric cover part of the duct and conceals those material ends .....It appears that the fabric cover stops at the actuator bracket point, however; an inside pipe ( or duct) continues on through the bracket to make a complete run , fore and aft along the cabin walls. These are just my thoughts and observations working with limited images,and very subject to change.
I see your point about the Dado and how it may have been fastened to a strip of wood to allow it's ease of removal or installation. Are there any larger holes in the bottom of the dado edge, or holes that indicate a spinning fastener that would indicate a few attaching screws were placed at the ends or staggered along the length of the dado?
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I see your point about the Dado and how it may have been fastened to a strip of wood to allow it's ease of removal or installation. Are there any larger holes in the bottom of the dado edge, or holes that indicate a spinning fastener that would indicate a few attaching screws were placed at the ends or staggered along the length of the dado?
Whatever they are, they're not dados. The are no large holes in the right-angle flange where the structure was attached to some surface. The holes are uniform in size and appear to be nail holes, not rivet holes, so the surface to which it was attached apparently wood.
Look at the drawings and photos in https://tighar.org/Publications/TTracks/2004Vol_20/undados.pdf and https://tighar.org/Projects/Earhart/Archives/Research/Bulletins/51_HeatShields/51_DetectiveStory.html
The heat shields would be permanently nailed to the wooden strips. The wooden strips may have had some kind of removable fastener that permitted them to be easily dismounted from the flooring.
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Ah yes,pardon....Had dados on my mind.... meant heat shields.
Would really like to get a better look at what the object next to the last tank is. It may be a play on eyes, but does the shadow near the bottom of the tank look darker and a slight line above the darkest at about the height a heat shield would be?
The darker shadow near the tank bottom is more noticeable in https://tighar.org/Publications/TTracks/2004Vol_20/undados.pdf however; I couldn't copy that image.
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Would really like to get a better look at what the object next to the last tank is. It may be a play on eyes, but does the shadow near the bottom of the tank look darker and a slight line above the darkest at about the height a heat shield would be?
This is the best I can do. There's something there.
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Anyone here expert in understanding shadows cast from flash photography? From my layman's perspective,...if an object such as a heat shield or other panel were placed next to the tank, and a photo was captured at the angle we see, my best explanation for why the lower portion of the shadow looks a bit elongated on the lower aft end nearest the actuator cover, and appears darker at the bottom with a seemingly straight looking break line ,is because the light from the flash had a smaller channel ( from panel to fuselage, than from tank to fuselage), in which to reflect ,and the panel being closer to the fuselage wall than the tank itself, it created a bit of an elongated shadow near the bottom.....but, that is no expert opinion, just guessing, I could be totally wrong.
As far as what appears to be a break line , between dark shadow and darker shadow, I don't know if one could determine the panel height using it's position on the fuselage wall, it may be taller/shorter than actual, due to the angle of capture....Only the shadow knows.
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As far as what appears to be a break line , between dark shadow and darker shadow, I don't know if one could determine the panel height using it's position on the fuselage wall, it may be taller/shorter than actual, due to the angle of capture....Only the shadow knows.
This is interesting. Great observation Jerry. There is definitely a "bump" (what you call a "notch" or "break") in the shadow. Something caused it and it seems like it must be the thing, whatever it is, that is just visible between the tank and the heater duct. Determining the height of the "bump" is going to be really tricky but should be possible by getting the height of the heater duct from the engineering drawings. I measured the height of the artifact from the top edge to the bottom of the right-angle flange where it was nailed to a wooden surface. It's exactly 6.5 inches. How tall is that strip of wood? Maybe an inch? Is that bump in the shadow the right height off the floor allowing for distortion caused by the angle of the light that is causing the shadow? This is really getting down in the weeds.
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As far as what appears to be a break line , between dark shadow and darker shadow, I don't know if one could determine the panel height using it's position on the fuselage wall, it may be taller/shorter than actual, due to the angle of capture....Only the shadow knows.
This variation of the shadow could be a wrinkle in the fabric cabin liner. I see what appears to be a lot of creases or wrinkles in the fabric cabin liner in the overall picture. They seem to occur more often where the cabin roof curves.
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I'm wondering if the purpose of the "heat shields" might be to deflect forced air from any heat duct outlets to go up toward the cabin space, and away from the space beneath the tanks, where it could, over a period of time, warm the fuel, and prevent the occupied space from being heated.