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Fuel cap question
http://thorp18.com/thorpforum/viewtopic.php?f=24&t=7920
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Author:  James Grahn [ Sat Apr 02, 2016 3:11 pm ]
Post subject:  Re: Fuel cap question

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

Author:  Rich Brazell [ Sat Apr 02, 2016 3:26 pm ]
Post subject:  Re: Fuel cap question

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 ! :o

RB O0

Author:  cluttonfred [ Sun Apr 03, 2016 9:43 am ]
Post subject:  Re: Fuel cap question

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/.

Author:  Rich Brazell [ Sun Apr 03, 2016 11:02 am ]
Post subject:  Re: Fuel cap question

Attachment:
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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 O0

Author:  cluttonfred [ Sun Apr 03, 2016 1:05 pm ]
Post subject:  Re: Fuel cap question

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

Author:  James Grahn [ Mon Apr 04, 2016 4:20 pm ]
Post subject:  Re: Fuel cap question

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

Author:  Rich Brazell [ Mon Apr 04, 2016 4:59 pm ]
Post subject:  Re: Fuel cap question

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 O0

Author:  Ryan Allen [ Mon Apr 04, 2016 6:10 pm ]
Post subject:  Re: Fuel cap question

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


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.

Author:  dan [ Mon Apr 04, 2016 9:28 pm ]
Post subject:  Re: Fuel cap question

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

Author:  John_Arnold [ Tue Apr 05, 2016 9:28 pm ]
Post subject:  Re: Fuel cap question

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

Author:  cluttonfred [ Tue Apr 05, 2016 11:58 pm ]
Post subject:  Re: Fuel cap question

John_Arnold wrote:
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.

Author:  flyingfool [ Wed Apr 06, 2016 9:49 am ]
Post subject:  Re: Fuel cap question

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.

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