Thorp Air Command - T18.net

I'm splitting the fuel tank conversation from the "anniversaries" thread to this location.

In my opinion the fuel tank in the Thorp is in the absolute safest location, right behind a motor, engine mount and a big huge A-Frame gear, sitting secure in a cradle, surrounded by the some of the heaviest material in the airframe (spine, heavy angles on the sides, external doublers etc). In the early days there was concern about exposed fuel caps "popping" off (caps w/o a positive lock) on impact and leaking fuel. That has long since been addressed with positive locking caps.

Wing fuel is good to have for extra endurance but I burn that stuff off first! I challenge you to find a banged up airplane that did not take damage to the wing, igniting fuel out there is still close enough to get you and a lot more vulnerable than in the fuselage. Thorp knew what he was doing!

Again ... an opinion!

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

And I can't imagine that any airplanes are flying with glass gascolators or fiberglass fuel tanks. Different era, different time. From what I remember - Dad had issues with the fiberglass and seepage. N45881 had an aluminum tank and never had any issues. Rich Shoup owns the airplane - Last I talked to him he was in the middle of a strip and paint.

Never really gave a whole lot of thought to the location of the Tank in the Thorp, but I have thought a whole lot of the fuel tank in the car, the tank that I am all but sitting on top of. I regard getting T-Boned on the way to the airport a whole lot more likely than bending up the bird. The airbags all over in inside of the car will keep me in place and alive long enough to feel the fire when the tank I am sitting on decides to erupt. I don't have any bags around the tank.......Dan

Just to continue to play devils advocate,

The fuel tank in a car is very romote to the heat source of the engine which one would think would spark the fire (outside of the caytalitic converter). In most cars the fuel tank is in the very rear of the car while the engine and the thing that is going to be the main probability for a fire is at the other extreme end of the car up front. A leaking fuel tank 10 feet way from the hot engine would seem to be a little safer than if the fuel tank was between the engine and dash board and right over the top of the hot exhaust. I also think that cars have fuel shut off valves that are suppose to shut off all fuel to the engine with a certain G load impact. But I'm not sure about that.

I agree with you that youre risk of injury in a car is higher if for no other reason is that your exposed to time in a car in far excess of how many hours a year you spend flying. (at least for most of us). Besides I trust other pilots in their planes than I do most of the drivers I see out there! I for one am glad that it is not "easy" to get a pilot's certificate. Otherwise we may end up with what we see on the road with some of the quality of the drivers on the road. Wow!

I fly now with maybe the worst of both worlds. I fly a 1946 11AC Aeronca Chief. It has a fuselage tank (15 gallons) in the nose just under and behind the instruement panel. In addition the Chief also has an 8 gallon aux tank located behind the baggage compartment. So the occupants are literally between two fuel sources. The rear fuel tank if it were to rip loos would smack into the back of your head. The difference only being that an Aeronca's impact speed is far lower and thus far less energy on impact than somethingfaster like a T18. Energy is exponential to speed. I think by the square of the speed. So even a small increase in speed significantly increases the energy upon impact.

The most asinine thing I think I've ever seen is that on my Aeronca Chief there are actually two cigarette ash trays on the instrument panel. Who the heck thinks it would even be remotely a good idea to smoke sitting between two fuel tanks within inches of the ash tray!!!!!! unbelievable. The ash trays do make a very good place to store ear plugs however

This is an interesting subject. Personally I think the fuselage tank makes sense to have gravity feed and keeping the engine running is imporatnt ALL the time, while worrying about impact during crashing is pretty remote chance and has so many variables that occur that each accident is so unique that keeping the fuel system clean and simple makes the most sense to me.

The complication of routing fuel lines and fuel pumps and possible failures in any of that complication versus the single straight gravity feed system doesn't seem worth the potential of maybe safety improvement of removing the fuel from the standard fuselage tank.

The idea that there is a better chance that a wing is damaged enough to rip through a fuel line in an accident versus being "protected" behind the structure of the fuselage makes a lot of sense. At least to me.

If you ride a motorcycle, like millions of people, you have a fuel tank between your legs. Those of us who have built Thorps, & those who own and have studied them realize what a truly wonderful design it is. It has withstood the test of time, including its fuel tank, for over 50 years. Have there been fuel tank rupture incidents? Yes, but very, very few. Pretty much most any airplane is vunerable to fire in the event of a serious crash.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

I agree John. With my S18 I'm sitting in a mine field with main tank and two wing tanks totaling 62 gallons. Trick is not to set off the fuse, as crashing is not good for your well being.

Remember the Ford Pinto ? BOOM !

RB

Dido Guys, fast moving fuel tanks taking an impact is not good, like Rich says BOOM!!! Dan