Thorp Air Command - T18.net

I have to pull the fuel tank to fix an unrelated problem but while I have it out I figure I might as well open this can of worms too. I would like to make the fuel shutoff a little more user friendly and run the line forward in a straight line though the strainer to the carb. I have read posts where people only have two 90° elbows in their gravity feed system so it should be possible without too much heartburn but I could use ideas or pictures on what people are using to make it happen. Thanks.

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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

Man, that's a frightening picture! Brass fittings and hose clamps with a kink in the hose

Yeee Doggie ! I know what I will dreaming about tonite ! A fuel valve you can not reach to turn off in flight (looks like the valve I have on my hot water heater ? . Worm gear clamps . Standard issue flex hose ! A very good idea to change this out when the tank is out .

1. Move the fuel shut off valve from the bottom of the tank (plenty of info on why not to put it there) to where you can reach it in flight or install a shaft to it where you plan to locate it so it can be closed .
2. SS braided hose with AN fittings/fire sleeve or an aluminum line with AN fittings can be installed .

I used the SS braided stuff w/AN fittings attached to an ANDAIR fuel shutoff valve . A little pricey for the valve , but I like the positive detents it has for ON and OFF . Plus a well labeled face plate . Made by the Brits .

RB
Hose Me

The shadow from the tape is in a bad spot. Really not very close to being kinked but it should not be twisted either. An elbow would have been a better choice than twisting the hose.

The ANDAIR valves are nice but I need help understanding how to install one while keeping the use of the detents and keeping the plumbing simple for gravity feed in the process.

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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

I put my Andair Valve here...
1. Easy to reach .
2. Easy to see .

Not much to hook up . Fuel line in , fuel line out . I have seen them mounted in various other places , but always easy to reach and see . Google ANDAIR products and they have a very nice web site . I believe I got my valve from ACS ? Has worked perfectly since day one .

RB

I was thinking you have a fuel pump in there somewhere?

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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

I do , but the FSOV is actually lower than the one you show in your pic . Gravity feed should not be an issue .

RB

Hmm...much of the same "info" you referenced above concerning the evils of having the valve mounted on the tank also talk about having as few 90° elbows in the line as possible in a gravity feed system. I also seem to recall something posted about using as short of a run as possible. Some of that info also talked about how adding fuel pumps actually decrease reliability (more failure points). There was more than one testimonial about how having the shutoff valve mounted like mine hasn't cause them a problem in 40 years. The recurring theme was "KISS".

While what you have is a very pretty setup, I cannot see your lines and it seems to me like your setup would add two 90° elbows and you definitely added length to the run. I believe it was Lee Walton who posted he only had two 90° elbows in his setup. Elevation of your valve in relation to mine is irrelevant since everything to the strainer should run downhill even when the tail is on the ground. If it doesn't then it isn't any better than what is in the picture I posted above since condensation will pool at the lowest point along the route. What did yours do when you gravity tested the fuel flow?

_________________
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

The Old NL's have several articles about not mounting the valve on the tank due to possible cracking problems at the attach point . The other problem having the valve at that location (other than the obvious safety issues) is it rarely gets "exercised" from on to off and with most of these type valves they are prone to "freezing" in the on position . If you have a ball type valve at your house that has not been cycled in years then I would bet it is frozen in the on position . I am sure there are folks out there that have that kind of mileage/40 years on a tank mounted valve and have not had any problems .

With regard to your set up all I can say is build and test . You are correct with regard to the KISS principle . There are probably as many different fuel set ups as there are airframes flying . I don't recall my output when I was building . I use a boost pump for T/O and landing , it makes me tingle when it is on ! I also used the Tony B. Firewall Forward Book (EAA) as a reference source when I did my system .

RB

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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

Rich, your system is a good system (that is a control cable clamped to the tunnel...right?) and I did not mean to imply anything else (I think I saw a drawing of one similar in a news letter). If I was building I would likely go that route but what you don't seem to comprehend is I am not building or rebuilding this airplane. I bought this aircraft to fly so I am looking for suggestions that actually promote that goal. If I can't have the airplane back together to fly in half a day I prefer not to mess with it. Removing the tank is likely to break that rule but I can't let the oil pressure line keep chafing on the firewall. While I am in there with, room to work, I am going to do something with the fuel lines and valve but I don't have a pedestal on my tunnel and my pitch trim wheel is forward of my flap handle (where I can barely reach it). I am not going to turn it into a major project I don't have time for so KISS is the order of the day and mounting the ANDAIR valve or similar within arms reach is not simple in this case.

_________________
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

Jeff : I guess I miss understood your intentions . I was under the impression that you wanted to incorporate an entirely new fuel set up in the cockpit . If all you want to do is "clean up " what is there then replacing a few items may be your goal . I can only offer what I did from hours (probably weeks) of "homework" from the NL's , looking at other set ups and going on line looking at other builders (including the RV guys ) to see how they roped this steer . It's experimental...you are free to do what ever makes you comfortable .

Cable ? Probably the coax for the two cans and a string radio !

RB

Some times the KISS technique does not work with airplanes, Just because its called an Experimental does not mean it won't fall out of the sky because of a short cut KISS. Looking at the pictures posted brass is not the choice for fuel connections as it is brittle and hose clamps loosen up over periods of time. How many factory built aircraft do you see using your setup.

An experimental can get you into deep trouble just as easy as a certified aircraft. I own both, and ensure that the quality of work that goes into any repair is something I am willing to bet my life on, because it is. The FAR's and other and approved practice's are for everyone's safety, both for experimental and certified aircraft. From the short time, I have participated on this forum I have found very helpful folks that seem to have my best interest first in there opinion and advise. I personally want to thank all of them for the sincere effort they have made to help me keeping a 39 year old experimental aircraft safe. Additionally, flying any aircraft that is not in a safe condition for flight, is just asking for a unpleasant outcome for themselves, passengers and people who trust us on the ground.

Phil Albee
N118BC Thorp T18
N7386Y Piper Twin Comanche

Phil, Just because someone doesn't want to redesign a 40 year old airplane that someone else built doesn't make them unsafe. There are other ways to fix this properly than copying the setup Rich is using. Many aircraft certified in other categories use shutoff valves in remote locations and use push-pull cables or shaft extensions to operate them. The AT-502, for instance, has the shutoff valve 2 feet below the cockpit floor. The C-188 has the shutoff valve on the belly in front of the rudder pedals next to the fuel pump. Even the shutoff valve in the J-3 is mounted out of reach and it's control isn't exactly easy to reach (I can't reach the carb heat in L-4 I occasionally fly).

Personally I am disappointed by the responses I have gotten here (except for the PMs). I was pretty specific as to my goal in the opening post but all I have received is a push to spend all winter redesigning the cockpit layout instead of help with using what is there. The trim wheel is visible in the picture but some may not recognize it or have a clue what it is attached to. I could still put the valve on the tunnel without a major redesign but the valve would be even with my ankles and still out of reach unless I slip out of the shoulder harness. At least it would be possible to reach it if needed (like the J-3 when solo in the back seat). A new J-3 style valve costs half that of the ANDAIR valve and would be just as "right" remotely mounted with easy access to a control device. Even ANDAIR makes an extension handle for remote mounting. For that matter, swap out the brass and the clamps, plumb in a gascolator at the bottom and the hose routing could stay the same (minus the loop) without compromising safety since there would be a way to check for and drain any water from the system. KISS works just fine in aircraft but it may not be exactly what is expected. There are many ways to go and not every Thorp is using the setup in Rich's pictures but they are just as "right" and "safe". At least some of them should be anyway. Some may be like mine or even worse.

_________________
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