Thorp Air Command - T18.net

Hello Thorpies,

Anyone out there knows anything about Tom Hunter's external fuel tanks, specs, installation or whatever else?

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In CowTown USA,
Don D-Day
NX18DD

I do recall his were composite, and mounted to the outboard end of the inner wing. I really like his youtube video: https://www.youtube.com/watch?v=a9_TqOB6_Jk
"Feisty" my T-18 is apart for repair & upgrades, fabricating a pair of similar tanks from aluminum has crossed my mind..

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Scott Emery
EAA Chapter 326
T-18 N18TE

I believe that the famous star of insurance ads (along with his Thorp), who also happens to be the moderator and keeper of this forum, has a set of them on his airplane. Hopefully Mr. Walton will chime-in, and correct me if I'm wrong.

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

Lee posted info and great pictures showing the installation. You'll have to dig... they are probably on the previous website in his album.

D

I was just looking at them last night. http://thorp18.com/forum/topic.asp?ARCH ... IC_ID=5781

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

Hey Guys .. there were only two sets made .. both are spoken for. No Plans.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

2.5 to 3.0 on the meter is about as long as I want to go before me bladder blows ! So no thought of extra tanks are in the works for me . Has anyone given the thought (if your heart is set on external tanks) of using thin wall large diameter aluminum tubing ? Surely (and don't call me serious) someone can fab a bullet nose and weld it on with a back/end plate welded on ?

RB

The Man with the Star

I was thinking along the lines of aluminum tanks myself if I attempted it. I hadn't thought of using tube but I like the idea. At the same time, I don't like being in an airplane much over 2 hours at a time anyway... full bladder or not. Currently, I break my 3 hour commute into a 1.7 and 1.3 depending on the winds because I haven't convinced myself I can do it none stop on 30 gallons and have any reserve... yet.

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

During jet training we had the ability to jettison external fuel tanks . I am sure the T-18 would fair well with MT tanks , but I am not sure I would like to be along for the ride with (2) full external tanks during T/O and an off field landing among the tumble weeds and rocks !

RB

Well Thorpies,

I've built three sets of integral fuel tank wings for other Thorpies and building externals would be much easier. A local Thorpie is interested in external tanks and I could have some built for him if I had more details.

My airplane holds 62 gallons in all. Some will argue that it's too much fuel and a waste for having to tote that amount. I've been told the effort to get the airplane going with that much fuel negates economics because the engine uses more fuel to carry the load. On my way to Lakeland last April, I climbed to 9500, trimmed engine for 2470 rpm and 6.2 gal/hr, 1390 EGT, covered 600nm in 4 hrs and used 29 gallons. They tell me also that more than three hours in the Thorp and they're ready for a walkabout. I too like to stretch my legs after those kinds of hours in the Thorp.

My reasoning to having the ability to carry that much fuel are multifold. Don't have to worry about getting fuel at a rest stop, because it so happened, an airport I landed at did not have a working pump. If I didn't have the fuel onboard, I'd be stuck for who knows how long. In the '70s there were no credit card pumps and fuel had to be pumped by a lineman. Sometimes I would arrive at the airport at dark thirty and everyone was gone. Had to sleep over on the couch if I gain access to the FBO or sleep on the porch. Don't have to do that anymore. I can fly from Fort Worth to New Orleans and back and not worry about fuel. I can fly non refuel to Lakeland, FL if I wanted to. If I decided to fly to Mexico, I can do that too without refuel.

So, you see, having the ability to carry more fuel gives you more options.

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In CowTown USA,
Don D-Day
NX18DD

I too, have 62 gals. , 33 in the wings, (which is supported by the wing in flight). I can choose my airports for fuel and pass up the ones that want big $$$$ for their fuel. Weather can play a factor in fuel on board, as I can fly over a lot of weather. Bob and I have flown fry Kentucky Dam to Lakeland non stop on top of weather. Remember,the only time you have too much fuel on board is when you are on fire.

Don,
Your friend is still 100% able to make a set of tanks .. the mounting is clearly outlined in the post listed above. As far as design specs .. there really never were any. Tom Hunter modeled them after an F-86 drop tank .. he admittedly did it because he thought it would look cool .. not for efficiency. Unfortunately Tom is no longer with us (hence the 'no longer available'). Having had a set I can tell you they were not the best solution to extra fuel. There's a reason no-one puts their tanks out side the aircraft by default and that military aircraft jettison their tanks when going into combat.

As Bill stated integral fuel tanks 'lift' their weight ... those external tanks were drug through the air. I would think anyone building/owning or refurbing an aircraft would prefer to 'do it right' rather than quick.

Best options ...

Larger main tank (Dave Read carries 40 gallons)
Wing Tanks - (62 gallons)

Again there was no magic to the drop tanks .. just an aerodynamic tube with a filler cap, drain, bulkhead and an aft support. That's it.

Lee

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

If I had to do it over during the building process I would go with the DR larger main tank . No other "special" tanks needed , extra plumbing , no timing , no pumps and worrying about a leaking wing tank . The external tanks do look "cool" , but in my opinion pose an unnecessary risk . One last blast from Pappy , I think you would spend as much time fabing , installing the "extra" tanks as you would making the main tank larger and have far fewer hemorrhoids !

RB

I own Bill Cordoza's Thorp, He had the Trusty wing built and installed that includes a 8 gal tank in each inboard strake. He was never able to get the venting for these tanks to stop leaking. I have installed a check valve in each wing tank vent to hopefully address the issue. The problem is that the vent is in the outboard wing panel about level with the mid way level of the tank allowing it to siphon any fuel above 1/2 full. I talked to Lyle just over a year ago, he advised that the vent should have went aft of the cockpit to address this problem when the wing was installed. I have been working on other issues and am trying the check valves first. So I should be able to carry about 45 gal.'s total if this works.

Phil
118BC

Does anyone know of a way to monitor the fuel flow(pressure) from wing tank that is pumped into the main tank so there would be an indicator(light) indicating no pressure ie wing tank empty.