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On 2 Apr 2006 23:37:06 -0700, "flybynightkarmarepair" <ryoung@lmi.net>
wrote:
>Wag-Aero has a special this month on quick drains:
>http://www.wicksaircraft.com/catalog/product_cat.php/subid=6879/index.html
>
>I am building a mongrel dog of a low wing airplane that uses wing tanks,
>pretty much like the Hummel Ultracruiser Plus. The tanks themselves
>are .032 aluminum. The question of the day is how to mount the drains
>to the tanks.
>
>2 styles and several sizes of drains are offered. The use either
>tapered pipe thread or straight threads.
>
>Obviously, a doubler will be needed to provide enough meat to fasten
>the drains to. The question is to whether to make a fairly thick
>doubler, and tap it for the tapererd pipe thread, or to use a somewhat
>thinner doubler, tap it for straight threads, and put a shear nut on
>the inside of the tank, before pro-sealing it up.
>
>How thick should a piece of 6061-t6 be in order to securely hold 1/8"
>NPT threads? I think I am leaning toward that solution, with the
>doubler OUTSIDE the tank skin to keep the un-usable fuel down a bit.
>Looking at my "Machinery's Handbook", I would need 0.2639" for full thread
>engagement. Can I live with less than that? What do RV's use in this
>area?
>
>OR, am I barking up the wrong tree entirely, and I should grab a
>welding flange, drill some holes in it, and slap it on with rivets and
>pro-seal, and let it hang down.
>http://www.aircraftspruce.com/catalog/appages/alumflange.php
>
My murphy rebel uses a welding flange pro-sealed and rivetted on. Pipe
threads are the way to go cuz sooner or later you're going to have to
replace that valve and it would suck if you had to open the tank to do
it.
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Re: Drains in Wing Tanks
