Homebuilt Fuel Tank ("Cell") Design and Fabrication

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Vigilant1

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I'm interested in designing and building a fuel cell that provides a measure of protection about the same as the commercially available models for amateur racing. I've looked at the off-the-shelf designs and they don't seem to fit the bill on at least two counts: They'll never exactly fit the very limited, precious "good spots" in the airplane (every cu inch not used is a bit of fuel left on the ground, and it adds up), and these things are pricey (I can only imagine what these companies pay for lawyers and insurance, and it's all reflected in the prices).
I'd also like the tank to be resistant to current and likely future fuels/fuel additives. That's a tall order, since no one quite knows what good idea the government will mandate next.
Current thoughts:
- Tank:
-- Inner layer: A welded AL inner tank (more fuelproof than any plastic, rubber, etc. Light, reasonably tough).
-- A hand-built elastomeric layer on the >>outside<< of the tank. Maybe fairly thick sheet rubberized compound heat-glued at the seams, or a liquid product that will form a sheet but remain flexible, perhaps with fibers included to improve tear resistance. This is to provide a backup flexible fuel containment "bag" if the rigid tanks are compromised by crushing, and the flexible nature of the material may reduce the amount of leakage if there's a piecing intrusion of the tank. Also, the flexible layer provides some mechanical isolation between the rigid layers so a break/crack in one isn't propagated to the other.
-- A composite "toughbox" on the outside. Probably Kevlar composite with whatever epoxy matrix seems to have the best chance of surviving the most likely fuels, if needed.
- Fittings: self-closing breakaway hose fittings (vent and supply, return also if using EFI) and a robust filler port.
- Other:
-- "Safety foam" in the tank. I'm on the fence on this--I'm not sure any of it is 100% compatible with real fuels and additives, and a fuel filter clogged with "foam goo" doesn't make for safe flying. I'd go with expanded AL "foam" if I thought I'd be taking hostile gunfire, but I don't.
-- Fuel bladder: Putting the flexible, collapsing "bag" inside the inner tank has many advantages (reducing flammable vapors, etc). But successful home-fabrication and fitting of such a bladder seems unlikely, and the questions of resistance to present and future fuels would remain. The constant flexing/folding of these bladders increases the likelihood of eventual (undetected) failure with potential trapped/unusable fuel issues, etc. So, in a perfect world I'd like bladders, but as far as I can tell their negatives outweigh positives in this application.

Thoughts, criticisms, open laughter?

Mark
 

Mac790

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

-- "Safety foam" in the tank. I'm on the fence on this--I'm not sure any of it is 100% compatible with real fuels and additives, and a fuel filter clogged with "foam goo" doesn't make for safe flying. I'd go with expanded AL "foam" if I thought I'd be taking hostile gunfire, but I don't.

If you by "safety foam" mean baffle foam, the best you can get for automotive aplication is made by ATL. Here you can get a replacement foam, for the ATL fuel cells ATL Saver Cell Replacement Baffle Foam - Demon Tweeks I usually do shopping there, and personally I'm extremely pleased with them. But like I said for automotive.

Seb
 

Vigilant1

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Seb,
Yes, foam like that. There are several brands, here's another: Crest Foam Industries - Products - SafeCrest . It does serve as a baffle (reducing fuel sloshing) but it also fills up the "ullage" space within the tank, making explosions from static discharges (or tracer rounds, etc) less likely. For our application, I think it's primary value might be the reduction of "splash" and rapid vaporization in case of a very big breech of the fuel cell.
I note that the link you provided is for replacement foam, and that the manufacturer notes that the stuff degrades and should be inspected/replaced. That's a worry. And, if my fuel tank, built as I would like to build it, really does split wide open so as to allow a "splash", then I think we may be beyond the realm of survivable crashes. But--maybe not.

The other contender I know of in this category is metal mesh products. They do the same thing as the plastic foams. One well-known product of this type is "ExploSafe", it is made of aluminum. It's had a good record in military aircraft (as far as I know), but I don't know if it will hold up to alcohols/water in fuels.

All these "tank fillers" make it hard to inspect/repair a tank from the inside, complicate the installation of fuel level senders, and increase maintenance issues. So, a tradeoff. I note most GA airplanes don't use the stuff, maybe for good reason.

Thanks for the input.
 

Mac790

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Mark,

On their webpage they also have "explosafe" type Demon Tweeks Easy Pour Fuel Tank Baffle - Demon Tweeks but I don't think it's a good idea to use it in the airplane, here is a short text from EAA webpage

eaa said:
"Explosafe," an expanded aluminum mesh used in fuel tanks to reduce the risk of fire and explosion in ruptured tanks, was breaking down and shedding aluminum flakes. These can block the flow of fuel. The recommendation is to remove the "Explosafe."
link Avoiding Fuel Related Problems

For GA I would say that the best idea is to keep fuel in the wings, as far as possible from the cockpit. If you really have to place it in the fuselage, maybe the foam from ATL might be a better option than that "explosafe". But it's really hard for me to say, it's a good idea. Personally I'm going to use foam for one of my next projects, but it's a car (single seater with fuel cell behind driver) and I don't want to have all that fuel in the cockpit immediately in case of puncture etc. But putting it into airplane, hmm. Keep it in the wings if you can, far away from the cockpit.

Seb
 

Vigilant1

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

For GA I would say that the best idea is to keep fuel in the wings, as far as possible from the cockpit. If you really have to place it in the fuselage, maybe the foam from ATL might be a better option than that "explosafe". But it's really hard for me to say, it's a good idea. Personally I'm going to use foam for one of my next projects, but it's a car (single seater with fuel cell behind driver) and I don't want to have all that fuel in the cockpit immediately in case of puncture etc. But putting it into airplane, hmm. Keep it in the wings if you can, far away from the cockpit.
Yes, I think I'll probably avoid the foams or AL inside the tank unless something convinces me the benefits outweigh the risks/hassle.
I like the idea of fuel in the wings--SUVSteve makes a good case for placing it aft of the spar (for mechanical protection the spar is hard to beat). For fuel in the wings no off-the-shelf fuel cell is likely to be satisfactory due to the odd shape of the available space. If putting it in the wings doesn't work for me, then it'll likely go behind the seat (pending a determination of CG issues). Obviously, that requires a robust tank that is very firmly fixed in place relative to the people onboard. Wherever it goes, a crashworthy tank will be safer than one built just strong enough to keep the gas from leaking out in normal ops. (which, unfortunately, seems to be the "standard" for many aircraft).

From a "total safety" perspective, the thing that is of most concern to me about a fuel tank in the fuselage isn't a post-crash scenario. It's a small fuel leak during the 99.99% of the time we are flying but not crashing. A leak in a wing tank, fitting, or line is a cause for significant concern, but an in-flight leak in the cabin is the stuff of nightmares. I sure wish we could burn diesel, Jet A or anything with a flashpoint above our normal operating environment temps. But, I don't think that's an option.

Thanks again.
 
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SVSUSteve

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Vigilant1 said:
- Tank:
-- Inner layer: A welded AL inner tank (more fuelproof than any plastic, rubber, etc. Light, reasonably tough).
-- A hand-built elastomeric layer on the >>outside<< of the tank. Maybe fairly thick sheet rubberized compound heat-glued at the seams, or a liquid product that will form a sheet but remain flexible, perhaps with fibers included to improve tear resistance. This is to provide a backup flexible fuel containment "bag" if the rigid tanks are compromised by crushing, and the flexible nature of the material may reduce the amount of leakage if there's a piecing intrusion of the tank. Also, the flexible layer provides some mechanical isolation between the rigid layers so a break/crack in one isn't propagated to the other.
-- A composite "toughbox" on the outside. Probably Kevlar composite with whatever epoxy matrix seems to have the best chance of surviving the most likely fuels, if needed.
- Fittings: self-closing breakaway hose fittings (vent and supply, return also if using EFI) and a robust filler port.
- Other:
-- "Safety foam" in the tank. I'm on the fence on this--I'm not sure any of it is 100% compatible with real fuels and additives, and a fuel filter clogged with "foam goo" doesn't make for safe flying. I'd go with expanded AL "foam" if I thought I'd be taking hostile gunfire, but I don't.
-- Fuel bladder: Putting the flexible, collapsing "bag" inside the inner tank has many advantages (reducing flammable vapors, etc). But successful home-fabrication and fitting of such a bladder seems unlikely, and the questions of resistance to present and future fuels would remain. The constant flexing/folding of these bladders increases the likelihood of eventual (undetected) failure with potential trapped/unusable fuel issues, etc. So, in a perfect world I'd like bladders, but as far as I can tell their negatives outweigh positives in this application.

Most crashworthy tank systems that have been developed, if they have metal in them at all, have it as the outside layer. Ballistic nylon and either a toughened epoxy or vinyl ester resin for the walls. Elastomers are used as a liner. There is no absolute need for a metal component in the wall to meet the rather stringent need of the US Army crash survival design guide. The only reason I would see it being possible useful is if you were looking to minimize penetration risks and there are better choices for that in the forms of some of the composite materials. Toray T1000G CF and Zylon PBO fibers (12K tows in a 2x2 twill or five-harness satin weave) along MTM49-3 or Cycom 2020 epoxy resin have been demonstrated to exceed the penetration resistance of most metal options with similar density and/or thickness in tests for FIA. If I were concerned about penetration resistance to the point where I needed exceptional protection, I would probably go with a system like that.

Trying to overlay metal with a composite interior might cause more issues than it solves and if you decide to go with that route, I would strongly recommend a drop test before finalizing the design. If you need help with that, let me know and I'll be happy to offer the test technique we used based upon the Army's test standards.


The other way you can reduce the vapor issue by using a lightweight (<2 lb) off-the-shelf nitrogen separator (basically a less complicated version of what the military calls an OBIGGS (on-board inert gas generating system) or what airlines call "fuel tank inerting"). You push the N2 into the tank and either dump the O2 overboard or run it into the cockpit which might help to offset the risk of hypoxia in a small tightly sealed cockpit. A simple baffle with one-way flapper valves that only open inboard would minimize the fuel sloshing issue.
 

Detego

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

... From a "total safety" perspective, the thing that is of most concern to me about a fuel tank in the fuselage isn't a post-crash scenario.
... It's a small fuel leak during the 99.99% of the time we are flying but not crashing.
... A leak in a wing tank, fitting, or line is a cause for significant concern, but an in-flight leak in the cabin is the stuff of nightmares.
... I sure wish we could burn diesel, Jet A or anything with a flashpoint above our normal operating environment temps.



What 'Fuel' will you be using in the "Fuel Cell"?
 

Vigilant1

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

What 'Fuel' will you be using in the "Fuel Cell"?
100LL or "gasoline" (as it's sold today). I'm using the term "fuel cell" here for a "crash-safe" fuel tank (as they are called in auto racing circles) not "fuel cell" as in a device for converting chemical PE to electrical energy. (English--so many words, but apparently not enough still!)
 

SVSUSteve

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

100LL or "gasoline" (as it's sold today). I'm using the term "fuel cell" here for a "crash-safe" fuel tank (as they are called in auto racing circles) not "fuel cell" as in a device for converting chemical PE to electrical energy. (English--so many words, but apparently not enough still!)

Yeah....unfortunately the electric airplane true-believers have made a search for "fuel cell" more complicated because you have to wade through lots of impractical and inapplicable information and disinformation.
 

Vigilant1

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Most crashworthy tank systems that have been developed, if they have metal in them at all, have it as the outside layer. Ballistic nylon and either a toughened epoxy or vinyl ester resin for the walls. Elastomers are used as a liner. There is no absolute need for a metal component in the wall to meet the rather stringent need of the US Army crash survival design guide. The only reason I would see it being possible useful is if you were looking to minimize penetration risks and there are better choices for that in the forms of some of the composite materials.
Yes, the main reason I'm looking at an AL inner tank is for fuel compatibility. The epoxies are resistant to "regular" fuels, but I've read so many reports of epoxy/FG fuel tanks leaking after introduction of fuel with other formulations (with ethanol, or with MTBE, since largely withdrawn from US use). These tanks had given years of solid service using "regular" gasoline. 100LL is still largely "pure", but the threatened elimination of lead makes me wonder what else will be introduced to allow aircraft to keep flying with the present compressions and valve seats. The other benefit to the AL tank is maleability. It'll dent and bend rather than crack and split (to some extent). If I don't have a flexible bladder (see above), then to my punkin brain having this maleable internal tank offers something if the composite outer hardshell takes a whack hard enough to crack it or crunch a corner. As a side benefit, the AL tank makes for an easy and reliable way to ground the fuel during refueling operations.

I learned a bit about "self-sealing" fuel tanks (useful mainly for smaller intrusions--bullets, etc). I'd assumed the sealant was some sort of goo or mastic that filled the hole. But another approach is to use a bi-layer fuel bladder with an inner layer that is compatible with the fuel and an outer layer that is not. When punctured, the incompatible layer softens, swells up, and seals the hole. If I stay with an AL inner tank, I might experiment with an outer bladder with one layer of EPDM (a "rubber" used for membrane roofing and pond liners). It's incompatible with gasoline, so maybe it'll "goo up" and be useful in conjunction with a layer of something that will keep its strength. Fun experiments await.
The other way you can reduce the vapor issue by using a lightweight (<2 lb) off-the-shelf nitrogen separator (basically a less complicated version of what the military calls an OBIGGS (on-board inert gas generating system) or what airlines call "fuel tank inerting"). You push the N2 into the tank and either dump the O2 overboard or run it into the cockpit which might help to offset the risk of hypoxia in a small tightly sealed cockpit. A simple baffle with one-way flapper valves that only open inboard would minimize the fuel sloshing issue.
Wow, a two-fer: A safer fuel tank and O2 for the canula without need for a bottle! I probably won't worry about the fuel ullage. I'd feel different if I were being shot at, I'm sure.

Thanks again for the input, it (and your offer of testing advice) is certainly appreciated.

Mark
 

SVSUSteve

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Yes, the main reason I'm looking at an AL inner tank is for fuel compatibility. The epoxies are resistant to "regular" fuels, but I've read so many reports of epoxy/FG fuel tanks leaking after introduction of fuel with other formulations

Look at some of the newer elastomers. They have excellent resistance to most solvents. Honestly, I think a lot of the crap that gets pinned on the "ethanol" is actually a lack of proper maintenance or just the arrogance of pilots to try to use a system for things it wasn't intended for. It's just easier to blame the "boogie man" of the fuel industry than to smack your friends upside the head and go "Hey, don't be stupid". If you want to use multiple fuel formulations, design accordingly. Doing otherwise is like trying to justify using a Piper Cub for unlimited class aerobatics and wondering why the wings came off....

Wow, a two-fer: A safer fuel tank and O2 for the canula without need for a bottle!

I don't know if it would produce enough flow for that. I honestly don't know if you could use to refill a bottle without some form of a compressor.

I probably won't worry about the fuel ullage. I'd feel different if I were being shot at, I'm sure.

If you have an electrical fuel gauge or pump, I'd go for the inerting system. 747s don't get shot at either and it does not take much to ignite fuel vapors....
 

Aerowerx

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

I'd also like the tank to be resistant to current and likely future fuels/fuel additives.

The most 'universal' container material I am aware of is glass. Resistant to almost everything. Of course a glass lined tank would be heavy.
 

SVSUSteve

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

The most 'universal' container material I am aware of is glass. Resistant to almost everything. Of course a glass lined tank would be heavy.

Pretty much unless you're dealing with very strong acids. Then they line even glass with a plastic or wax compound. There used to be a guy in my hometown who did glass etching using hydrofluoric acid. That stuff will eat just about anything but you can use beeswax to stop it from etching glass. One of the truly bizarre facts that I've picked up over the years. LOL
 

autoreply

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

I'd also like the tank to be resistant to current and likely future fuels/fuel additives. That's a tall order, since no one quite knows what good idea the government will mandate next.
I have personally dropped that requirement for the tank. (Still there for fuel lines and you obviously don't want any goo coming loose from the tank). Simply make it removeable, use the best coating you can find against ethanol and lead and inspect the tank yearly, build another one if it's penetrated. I'm planning to laminate a dozen or so smal pieces of glass standing up from the bottom. After half a year and then yearly, break one off, saw it in two and have a good look at the effects. We know that the effects of all additives happen slowly over time, so a regular check should do.

As for the fuel cell itself, I'm planning to build it up from flat pieces of glass (the epoxy variant..) with some slosh baffles inside. A generous thickness of polystyrene or other foam around and then corrugated kevlar/carbon mix around it. (Hotwire the polystyrene in a sine wave pattern and you can lay up wet and vacuum bag). Make sure the alignment of the "waves" is around the corners, such that you don't have stress concentrations and the outer shell can bulge out a lot, to absord the energy of impact.

Have a good look at the crash loads. 400 [email protected] 100 G's is a lot of force. Hence, mine ends in hardpoints that directly bolt to the firewall (pusher)
 

Mac790

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

I was wondering, are going to build an airplane from a kit, or do you think about a "custom" design. If you are going to design it from scratch, you could design it with fuel in the wings, and eventually put a small fuel cell in the fuselage, which willl feed an engine. But if you want to put it into the fusealge, I was wondering how big is this tank going to be? If it's going to be big don't forget about proper attachments. Those things at high acceleration might become really dangerous.

Here is short story about what might happen in an airplane with (in this case) an engine at the back, during a crash.
The requested autopsy by the family was impossible due to the condition of Jacks body and head as the engine came through the firewall and as one fellow put it, "effin squashed him like a bug".
link Jack Morrison's fatality - Page 4 - Canard Aviation Forum

I don't have any papers front of me about airplane potential crash scenario, but I have some about gliders (pic1,2), but for an airplane I would expect higher accelaration (higher speeds, etc).

In automotive I haven't heard about anyone buillding fuel cells. Usually you have two options, first an aluminium tank with foam inside (pic3), or if you willing to spend more cash, a proper ATL fuel cell, proper kit-car companies gives you an option. Those ATL has FIA certificate, so I don't think that anyone would be willing to pay extra $ for a fuel cell without certificate.

But if you really thinking about building one... Here is a cut section for the ATL fuel cell (if you haven't seen it already) PRI 2010: ATL All Fuel Cells | Dragzine Like Steve said if you want to use aluminium use it on the outside, not inside. If you don't want to use foam inside, it might be a good idea to add some baffles inside, I did some quick renderings (pic4). The question which technique are you going to use, probably some sandwich... The good idea might be to make some samples and test it (similar to those guys http://oatao.univ-toulouse.fr/4065/1/Rivallant__4065.pdf ), before you decide to build entire fuel cell, and drop test it.

Instead of building fuel cell, you might take a look at some extinguisher system Fire Extinguisher Packages - Plumbed In & Hand Held | Fire Extinguishers & Accessories | Motorsport | Home | Demon Tweeks

Seb
 

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Vigilant1

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

I have personally dropped that requirement for the tank. (Still there for fuel lines and you obviously don't want any goo coming loose from the tank). Simply make it removeable, use the best coating you can find against ethanol and lead and inspect the tank yearly, build another one if it's penetrated.
Interesting approach, especially with the built-in test coupons inside the tank. Cost-wise and for design flexibility, getting away from AL would be a plus (I can't do the welding myself). Avoides another disadvantage of AL--difficulty in forming gently radiused edges and corners (which are a lot stronger). The "possibly expendable" tank would be especially attractive if the fuel tank is easily accessible (i.e. not built into the wings and glassed in).

As for the fuel cell itself, I'm planning to build it up from flat pieces of glass (the epoxy variant..) with some slosh baffles inside. A generous thickness of polystyrene or other foam around and then corrugated kevlar/carbon mix around it. (Hotwire the polystyrene in a sine wave pattern and you can lay up wet and vacuum bag). Make sure the alignment of the "waves" is around the corners, such that you don't have stress concentrations and the outer shell can bulge out a lot, to absorb the energy of impact.
So, no rigid (epoxy/fiberglass) connection between the fuel container and the outer hardshell, right? The foam allows each to deform somewhat without compromising the other. The corrugations are a good touch, having two layers 90 degrees to each other would be deluxe at countering loads from any direction, possibly overkill. Divinycell or other PVC/fuel resistant foam might offer advantages over polystyrene foam in this application. PVC foams can't be hotwired, bit it would be easier still to make the sine wave with a router and a large coving wood bit.

I'm planning to laminate a dozen or so smal pieces of glass standing up from the bottom. After half a year and then yearly, break one off, saw it in two and have a good look at the effects. We know that the effects of all additives happen slowly over time, so a regular check should do.

400 lbs? Is that the engine weight plus the fuel, or are you designing something really big? I'll probably carry 12-16 gallons total, so approx 100 lbs (45 kg)
 
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autoreply

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Interesting approach, especially with the built-in test coupons inside the tank. Cost-wise and for design flexibility, getting away from AL would be a plus (I can't do the welding myself). Avoides another disadvantage of AL--difficulty in forming gently radiused edges and corners (which are a lot stronger). The "possibly expendable" tank would be especially attractive if the fuel tank is easily accessible (i.e. not built into the wings and glassed in).
I'm in exactly the same position. Tanks in the wing isn't going to happen (no room in the inner wings, disconnecting fuel wasn't such a good idea after all)
So, no rigid (epoxy/fiberglass) connection between the fuel container and the outer hardshell, right? The foam allows each to deform somewhat without compromising the other.
Exactly. While replying, I looked at my helmet. Skull, foam, outer shell. Seems to work fine to spread out the loads. Rigid connections between inner and outer composite shell are point loads and unless extremely strong will break anyway.
The corrugations are a good touch, having two layers 90 degrees to each other would be deluxe at countering loads from any direction, possibly overkill.
Or result in localized stress concentrations... Better to have a single corrugated layer. Such a corrugated sheet is the theoretical and practical optimum in terms of energy absorption in pressure. Avoiding any sharp corners helps a tremendous amount by avoiding (having to design for) concentrated loads.
Divinycell or other PVC/fuel resistant foam might offer advantages over polystyrene foam in this application. PVC foams can't be hotwired, bit it would be easier still to make the sine wave with a router and a large coving wood bit.
Possibly. I don't know the difference in energy impact between various foams. Polystyrene does weaken due to fuel, but not sure how relevant that is. It's sole functions are to keep the shape and spread out loads as pure pressure on the outer skins.
400 lbs? Is that the engine weight plus the fuel, or are you designing something really big? I'll probably carry 12-16 gallons total, so approx 100 lbs (45 kg)
Nope, just fuel weight. I'm planning to go far, at least that never changed ;)
 

SVSUSteve

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Hence, mine ends in hardpoints that directly bolt to the firewall (pusher)

Perhaps a breakaway system might be a good idea? They are pretty common in helicopters with fuel tanks towards the rear of the aircraft and might help to shed some mass during a crash which is a recommended approach in some sources.

Mac790 said:
The requested autopsy by the family was impossible due to the condition of Jacks body and head as the engine came through the firewall and as one fellow put it, "effin squashed him like a bug".

Any time the fuselage fails, that is often what happens. I have pictures of three bodies that was in a Mooney which hit a snow-covered mountainside which Even a "squashed" body can yield useful data from a pathology standpoint although it's going to likely make it difficult to rule out a stroke. In cases with a fully intact body, it's sometimes difficult to diagnosis a heart attack or stroke that is associated with a short survival interval (it can take time for unequivocal tissue findings to develop). In a lot of cases, the local coroner is hesitant to add additional work to their pathologist's schedule (there's a limit in the US on the number of autopsies a pathologist can perform per year to avoid quality suffering) and they don't see a point in a "straight forward plane crash". Honestly, in a lot of these case where the family goes looking for a medical excuse, it's because they don't want to admit that their loved one screwed up.

One of my friends died in a Cirrus crash here. His family swears up and down that he had an aortic aneurysm based on the autopsy findings. The aortic injury was from the impact with the pond and an aortic aneurysm made no sense with the statement the son (a passenger) made both to the deputy coroner assigned the case and the NTSB about the events leading to the crash. The plane was overloaded and he stalled during the climbout. It's sad but he simply made a serious of very bad choices.
 

autoreply

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re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Perhaps a breakaway system might be a good idea? They are pretty common in helicopters with fuel tanks towards the rear of the aircraft and might help to shed some mass during a crash which is a recommended approach in some sources.
Mounted to the cold side of the firewall in a pusher would put a certain forum member directly in it's trajectory. A bit more love for your fellow forum members would do you good dear Steve ;)
*Chuckles, with a big grin*



And the whole "engine smashed through the fuselage in a pusher" thingy is grossly overrated. If I can't restrain an engine that weighs the same as me, how on earth am I going to restrain ME in a crash?
 

SVSUSteve

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Evansville, Indiana
re: Homebuilt Fuel Tank ("Cell") Design and Fabrication

Mounted to the firewall in a pusher would put a certain forum member directly in it's trajectory. A bit more love for your fellow forum members would do you good dear Steve

LOL :p Well, this is where a multi-layer birdstrike resistant canopy gains another potential use. ;)

And the whole "engine smashed through the fuselage in a pusher" thingy is grossly overrated. If I can't restrain an engine that weighs the same as me, how on earth am I going to restrain ME in a crash?

It is. The only time it happens is when the fuselage is under-designed at which point it does not matter whether the engine is in front or back. Either way, it's coming through the cockpit. It's just a matter of whether you wish to watch you fate coming at you or not.
 
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