Thorp Air Command - T18.net

Small sample size, but it sounds like most folks have their cap under a door. That would mean I do not have to be flush mounted.
Cubes

The main reason I like my "flush cap" it that I don't have to worry about a fuel spill/smell in the cockpit with a cap under a door . A scupper probably eliminates this , but the added bonus with an exterior flush cap is seeing the cap place before takeoff . BOOM !

RB

Rich, just so I understand, does the neck of your cap bridge the gap between the fuselage skin and the tank itself or is there a separate neck on the tank and some sort of hose connecting them? As I don't yet even have my T-18 plans (though they are ordered!), I am having a hard time imagining the setup/.

_________________
Matthew Long, Editor
cluttonfred.info
A site for builders, owners and fans of Eric Clutton's FRED

« Voici ce que j'ai fait...vous pouvez en faire autant! »
"This is what I have done...you can do the same!"
--Henri Mignet (1893-1965)

My fuel tank came from Classic Sport Aircraft (CSA) and attached is a copy of part of the installation instructions and a pic of the "extension and flange" that is welded to the top of the tank . It was a VERY tight fit and the hole location for the CS attachment screws came from the modified machine screws ( ground down to a point) . The tank was placed in the cradle and the "screws" left a small dimple for hole location . A gasket was placed between the flange and the bottom of the skin . I am very happy with this set up . No fumes and a final visual check on the cap prior to take off .

RB

Thanks, that clears it up. Is anyone still making this sort of "extension and flange" component?

_________________
Matthew Long, Editor
cluttonfred.info
A site for builders, owners and fans of Eric Clutton's FRED

« Voici ce que j'ai fait...vous pouvez en faire autant! »
"This is what I have done...you can do the same!"
--Henri Mignet (1893-1965)

Hence the original question I posted about flush mounting. I need to know if there is a desire for that extension.
Cubes

Here's my vote...if I had to do it over I still would go with the flush cap/extension . Remember I am right 50% , one half of the time .

RB

If I were building, I would prefer the flush mounted one rather than one that can spill over into the cockpit like I have now.

I ran my tank vent into that extension, it is good for that it works great. That would eliminate a couple of components being welded into the top of the tank, and you can fill it to the brim and have no siphoning issues, I do prefer the flush lockup cap, even though the cap under the door has worked fine for years. That extension pops right into place on the assembly of the tank into the fuse, put the screws in and your done........Dan

I'm pretty impressed with Bruce's solution (British American Transfer http://www.batinc.net/aero.htm) although the price is a bit steep; but the look and function appear ideal. John

Yes, those are very nice, they are standard Newton caps from England used on sports and race cars and motorcycles and there are even more sizes and styles at http://www.newton-equipment.com. Still, I don't see any way to put the flush cap in the fuselage decking without using a custom part like the one Classic Sport Aircraft (CSA) used to make except putting a separate flange in the decking and a filler neck on the tank and bridging between the two with fuel hose. That would work but would require much more space between the tank and decking than the custom solution. If Cubes does not decide to offer the part, I suppose it would be possible to weld a bolt circle on an existing cap flange to fake it, but you'd need someone comfortable with that king of aluminum welding.

_________________
Matthew Long, Editor
cluttonfred.info
A site for builders, owners and fans of Eric Clutton's FRED

« Voici ce que j'ai fait...vous pouvez en faire autant! »
"This is what I have done...you can do the same!"
--Henri Mignet (1893-1965)

Flush top looks the most elegant by far. I like the idea of a locking tank. I would actually perfer all things being equal that the cap be domed or slighly high to shed most rain water etc.

Having a fuel door however almost certainly prevents any water from rain to enter into the tank if the flush mount cap would somhow leak.

Is there some way to have a "scupper" attached to the deck and also a recessed cap. So it could be covered by a door, yet the scupper/sump lower than the tank cap opening could be constructed with drain holes in it that are collected into a single tube so that any water or overflow of fuel could be drained overboard via this scupper tube so no fuel is spilled inside the cabin?

Other fuel caps on airplanes all over are subject to exposure and water so maybe it is nothing to be concerned about and we should always "sump" out and eliminate any possible water in the tank anyhow. But I have found a lot of water in Cessna fuel tanks. I'd rather have a design that best minimizes the possibility of water to enter the tank in the first place. Sumping is just double precaution.

Any latest solutions to the cap issue? I have had a new rubber seal made on a 3D printer...the material didn't work.
I know spruce has the ACS 10455 and 10460....anyone know if those are the same diameter? ...and need machining to fit our fillers? I know Cubes felt one he had didn't seal too well and left him with slight fumes in the cockpit.

This thread is quite old...so any better solutions out there?

thanks
Curtis

OK, 'just got off the phone with ACS....The 10460 includes the ring....the 10455 is just the cap. The woman I talked with had been there 18 years and is familiar with our saga. She said they made the rubber insert for our caps...well made our caps and the people that made the rubber part raised the price 4 fold 15 years ago and then they made the 10455 cap instead. And yes sometimes we have to shave a bit off the diameter.
I have three flush mount caps...perhaps Cubes was more susceptible to fumes because his cap is inside a door, whereas a flush mount any fumes wouldn't have a path into the cockpit. However I would hope the cap tight enough not to allow fumes.
I will order three and hope for the best! Mine old ones are nearly unusable at this point with the rubber becoming nearly solid.

Curtis

Keeping the fuel cap issue going has there been any new news on the topic?

Curtis did you get the ACS caps and install them? If so what was involved and how are they working?

I have the old cap also, I just removed the tank, so I can inspect the back of the firewall as I try to bring my T18 back to life, and thought before it goes back in I need to address the fuel cap issue. The easiest solution is if the ACS cap and my tank flange can be easily massaged to fit each other. My flange is 3.06" id at the top for about a 1/4" and then goes to 2.59" id at the bottom. Someone mentioned the Usher UD-3 cap and flange, that looks like a possibility to either glue (proseal or ) to the top of the existing flange or to cut/reduce the Usher flange from 3-3/4"od to about 3" od and glue it inside the 3.06" area of my flange. The possible ACS or Usher solutions are both pretty economical. It also looks like both have o-ring seals which should be available in the future.

Has anyone used and Usher cap/flange in a similar manner?

My other challenge while the tank is out is to address the scupper, the scupper consisted of a piece of foam cut and formed to fit the void from the tank to the boot cowl. It was then glued/sealed down to the tank and the faces toward the cap were covered with the same glue/sealant. Had a 1/4" aluminum tube stuck in on top of the tank and under the foam for the drain of the scupper.

What are some of the methods others have used to create the scupper?

I appreciate all of the input from this forum, it has been invaluable to me as I worked to find a T18 and now to revive it.

Thanks

Dave