Thorp Air Command - T18.net

Anyone tried or thought about trying these aux tanks made for an RV-4?

http://www.safeair1.com/HWA_RV4.htm

I am trying to find out the length to see if they will fit in the outer wing panels of a standard T-18.

Tim A.

Tim, not worth the effort. Search the forum / archives, we've discussed this before. There's not near enough capacity to make it worth the while.

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

What is wrong with the tried and true integrel wing tanks that are already installed in many Thorps????? Sealing the outer wing "D" section will double your capacity.
I designed rib access plates that combined vent tube, drain and supply fittings. The only wing skin openings are the filler cap on top (which could also be installed on the end rib vent and access plate) and the bottom skin between the middle ribs.

I was just looking at a Mustang II which has wing tip tanks. Seemed pretty nice, and looks great.
Has anyone made a set for the T-18?

This tip tank was for sale at Osh a couple years ago. Sorry, I have no more info.
BobMO

that's on an MMII ... Not sure how tip tanks on a Thorp could possiby work. If you want to go that route, talk to Tom Hunter. Pretty sure his drop tanks are as close to "tip tanks" as a Thorp is going to get.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

Yeah....Tom.
I was just thinking that his scaleable low drag body (tank) would make a good tip tank with a winglet like those straight wing '50's' era jet fighter bombers had?
I wouldn't want a tank that looks conventional like a Midget Mustang or on a Comanche.
John Thorp had a unique way, so I say go with it.
I just looked at some pictures of the Lokheed Scorpion. It's got both tip tanks and drop tanks on long unswept wings. and although they are slightly tapered wings as well as HUGE tanks, the idea could be scaled and toned down, with landing lights, anti-collision & position lights to fill the volume but not carry too much fuel weight.

Tip tanks do not lift themselves, the wing must carry the additional load. All of that weight out at the tip (especially an F-89 inspired tip ) would simply be way too much mass that far out on the wing. The wing would have to be beefed up which would add unessessary weight (not to mention spin recovery). If you need that much extra fuel consider wet wings, they lift themselves and actual ADD structural integrity to the wing when full. Go to the Thorp FAQs on the main page and look up the additional fuel question, I think that pretty much covers all the options.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

Interesting topic;
Pete Garrison built MELMOTH with tip tanks on essentially T-18 wings.
John Thorp was involved in the process.
However the MELMOTH was a different plane, with retractable gear midspan. That could support some pretty large tip tanks.
http://melmoth2.com/texts/Wing%20geometry.htm
Long range and speed were Pete's goals.
Not me; Light weight is my goal. If aux tanks are required, I usually think of removable tank ideas....like a fuel bladder, race car fuel cells, and Tom Hunter's tanks.
Lee, your point is well taken, but us newbies gotta ask, and dream.

Right, as you point out the Melmoth was a different animal, larger and heavier than the T-18, and he wanted very long range from wherever he could get it. Also note that when Garrison built the new and improved "Melmoth II"... no tip tanks, also later in Melmoth I's life he built new outer panels and disposed of the tip tanks.

Good topic though Scott!

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

About 1985 I looked at a T18 I think was in Tyler Texas.If I remember correctly the fuel was in the tips. That was were the fuel door covers were.I remember thinking I had never seen this set up. I got a picture of it somewhere.If I can find it I will post it.That way some one can refresh my memory if I am wrong.

That's not uncommon, sometimes guys put the filler door on the tip which leads to the outboard panel (some references in the newsletters too). Not sure why ....

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

Not a big fan of external tanks (sorry Tom), unless you have the capability ot jettision them. I for one would not like to take off with
fuel in the drops and have to make an off airport landing with them attached. Instead of "external tanks" I would opt for in this order...

1. Wet wings as discussed.
2. Baggage compt. race car crash proof tank.
3. Or......

Has anyone looked into the possibility of modifying the "main" 29 gal tank to hold more fuel ? I think it may be possible to lower the center section (U shape or V shape) between the "cradle" to accomodiate more fuel ? Just me letting out more brain gas !

RB

I think the best point of reference when it comes to adding fuel to the T-18 is N455DT. I don't think anyone had as much drive to put as much fuel in the thorp as Col. Taylor did. He tried just about every possible combination; under the seats, in the baggage comp, in the right seat, wings etc. In the end he ditched the under the seat tanks ( not worth the trouble) and the baggage comp tank (cg issues) and ended up with the standard main tank, wet leading edges in the center section, wet outboards (the entire panel was wet) and a right seat tank. I'd be willing to bet he considered external fuel and fuel in the tips and was discouraged by his own experience and by John Thorp as well.

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD