Thorp Air Command - T18.net

Nothing screams "PROBLEM" during preflight like a big puddle on the floor

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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

WE tend to overthink some problems. I have a fuel line that comes from the bottom of the center tank back to just forward of the spar to a fuel select valve, a line from here to the firewall thru fitting, short line to a Piper gascolator, a hard line to the electric pump on the firewall a flex line to the mechanical engine driven pump and finally a hard line to the HA6 carb. I copied the Piper fuel system and been working for 23 years. I have separate fuel pumps that pump fuel from the wings to the main tank via "P" tubes mounted at the top of the tank. As for the shutting off the fuel, I shut the fuel off at Oskosh and Sun n Fun and when using the plane as a glider, the rest of the time its on.

FWIW, I don't shut mine off either... not for 26 years! OK, so I shut it off to test it or for service every so often. I do pull the cowl cheeks & do a post-flight inspection after every flight though... if something's drippin' I'm gonna' see it. Sounds like a fine idea though.

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

Here is the cleaned up routing. It could be prettier but there is no place for water or debris to get trapped and it flow checks better than what used to be there. I had to lower the strainer 2 inches to maintain a downhill slope from the tank. It would have been easier to make the connections as I went but, given the limited space, I mounted the components first then tried to make the connections. I couldn't find a routing for hose that wouldn't kink or interfere with the rudder pedals AND maintain the downhill slope. Time will tell if it is a lasting solution.

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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

Simple. I like it. Is that a finger screen?
Cubes

The brass fitting is the large finger screen Aircraft Spruce sells. It originally had a bushing and the small screen. I gained a badly needed half inch or more by switching screens.

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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

Here's a new gascolator product that would solve the problem of tight vertical space in the T18. You could even mount the valve to the top of this thing if you were concerned about mounting it on the bottom of the tank.

https://www.flyboyaccessories.com/product-p/72rr02.htm

Does it serve ravioli and garlic bread for that price ?

RB

Interesting gascolator. I am not fond of the wire bail style I currently have. I had considered getting one from Steve's Aircraft that the shutoff valve could screw directly into but I was afraid it would not clear the cross tube. Instead I extended the existing gascolator bracket down because it already held the gascolator forward of the cross tube. I nearly clamped the gascolator to the cross tube but came to my senses before I made it permanent. I am thinking I will finish it off with a Saf-Air drain part # CAV-110H4. That particular drain should allow easy access for me to sump check the fuel system. I adapted a piece of 4130 tubing to help get the fuel into the cup until I remember to order one with one of my regular parts orders.

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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

While replacing the fuel tank float / sender (Stewart Warner #391B-F) I decided to tackle the old sticky fuel valve, directly attached to the tank. This is the thread where these concerns are hammered about, so here goes:
The finger strainer in the tank appeared clear enough. but when the valve and strainer were removed, the inside of the pipe nipple/strainer was half clogged. I cleaned it out by hand reaming with a snug fitting drill bit. This is something we should all think about. Maybe caused in this case by sitting 9 years with mogas in the tank, combined with condensation which rusted the fuel level sender..
I decided to upgrade the valve, so a brass Imperial 3-way valve (as used by Van's) was enlisted. It has a mounting flange with 1/4" bolt holes. You can see in the pictures that I intend to mount it at a 45 degree angle just ahead of the flap handle. AN Stainless Braided hose from the tank and to the firewall seems the safest. I'm still fabricating the console, the second picture was taken while measuring for the side panels.
The Aux Tank suction is for a removable 8 gallon Fuel Cell with top fuel & vent connections to sit on the baggage floor. This adds one hour range and only takes 9 inches from one side of the baggage floor. I ordered rubber hose for this to prevent chaffing. It's still rated to 200 psi, so it will be OK for suction hose.
https://www.summitracing.com/parts/rjs-3006501 the tank vent will loop up, then exit the bottom where the old battery vent/drain went before I moved the battery to the firewall.

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Scott Emery
EAA Chapter 326
T-18 N18TE

I like it. So no plan for a pump from the baggage fuel? The baggage fuel will be plumbed direct to the engine via that valve. Any thoughts on fuel delivery? I know it works from the underside of the turtle deck. Just wondering if it will work from that low. Interested because I plan to have fuel below the baggage floor in my racer....if i ever get time to work on that again.
Cubes

I must be conflicted. Yes I did add a fill port to the top of the tank when renewing the fuel level sender. When I was vacuuming the drill chips out of the tank, I decided the valve and strainer should be cleaned & upgraded.
Once committed to diving under the panel...may as well do a good job.
I had a few valve choices, and several different plans (a small sample of my mental ramblings can be found in these forum threads). To make all options easier, I decided to bring the valve aft rather than operate it from an extension rod. (add slight weight penalty)
"Feisty" has a Facet 'beer can' electric fuel pump and an engine mounted fuel pump, so a few inches of lift from the baggage compartment floor should be easy. Especially in cruise flight with the tail slightly high? The disadvantage is running the tank dry and the engine quitting. If I don't like it, I can install the pump for transferring fuel to the main tank.
The Facet 40108 fuel pump weighs 16.19 Ounces - a pound! The idea of carrying extra fuel weight is OK, the real problem is the weight of the container, hoses, tubing, valves, pumps & fittings. Don't forget mounts, anchors and clamps. Also the space they take up and the effect on CG. The obvious solution is in the wings...if you built them.

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Scott Emery
EAA Chapter 326
T-18 N18TE

Copy all. I’m anticipating being a bit forward CG. That’s why I was planning to put fuel there. But I was planning to use the space below the baggage floor. Also, I was planning to plumb the fuel to the header and always run the engine off the header.
Cubes

I had to remake about 2/3 of the fuel selector valve console, here it is as of today:
I added the blue elbow to the bottom of the tank, drilled the console to the tunnel and I'm ready to 'make hose'!
The hole on the left side of the console is large enough to accommodate a 1/2" socket wrench to remove the pipe plug in the 3 way valve. Then a -6 fitting can be installed if a third fuel tank is desired.



Here I am changing the combustion chamber on the Reznor waste oil heater for my hangar; comfy home of 'Feisty' my T-18.

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Scott Emery
EAA Chapter 326
T-18 N18TE

After spending the morning working on panel upgrades, I returned to the auxiliary fill fitting on the fuel tank. (I'm on vacation an the runway is snowed in, so 'Feisty' is getting some attention)
I was able to get a couple of fingers inside to position the doubler plate and ring nut, then install the anti rotation bracket and bulkhead fitting from the top and start threading the nut on.
After that I mixed up some Proseal and dobbed it into place with a popsickle stick. The challenge was tightening the nut. Eventually, after trying crow-foot wrench (13/16"), a spark plug wrench on a crows-foot plus a 6" extension..etc...plus electrical tape (don't ask)...I cut the end off this 13/16" combination wrench and drilled a hole in it for safety wire so I wouldn't drop it inside the tank. I was able to suitably tighten the assembly by using the 9/16 wrench to hold the fitting in place. Proseal is so messy!
Next, I shoved a length of Russell Rubber Twist-Lok hose aft over the fuel tank so be sure it would easily pass down the back of the fuel tank under the windshield. Piece-o-cake! Adding an auxiliary tank + booster pump system would be easy now.

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Scott Emery
EAA Chapter 326
T-18 N18TE