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Speed,Combat,Scale,Racing => Combat => Topic started by: Casey on January 16, 2020, 09:02:27 AM

Title: Metal Tank in Foam Wing
Post by: Casey on January 16, 2020, 09:02:27 AM

Hi Guys

I was advised to construct an engine bay of 3 mm balsa in my foam combat wing for the metal fuel tank so as to prolong the life of the foam wing but I rather just fuel proof the foam in the fuel tank bay to save weight.

So, what do you all think?

Title: Re: Metal Tank in Foam Wing
Post by: phil c on January 16, 2020, 02:31:27 PM

First off, I'd suggest using a bladder tank setup.  With a properly fine needle valve it gives a pretty consistent setting for a full flight.  It does take some practice getting the bladder to fill evenly. Depending on the needle valve you use the bladder can either have a 1/4in diameter by1/32in wall, or a 1/4in. diameter by 1/16in. wall.
Use T8 size fluorescent bulb protectors(Home Depot, Lowe's, etc.).  The Fora F2D needle valve works well, about $16, or the OS CL needle valve, for 20-46 engines.  The latest version has the middle, around the fuel hole, narrowed down to give a bigger venturi.  The threads/inch is around 100 thread/inch.

If you just have to have a metal tank I'd mount in between the spars, in a balsa box, open on top. Line the box with thin polyethylene bubble sheet- a soft, white plastic sheet about 1/8in thick.  If you lay it out properly you'll be able to pull the foam out and pull the tank out the rear for servicing.  Fill the rear of the box with foam to wedge the tank in for flying.  Make a mock-up before installing the box in the plane to make sure it will work properly.  Then you won't have to tear the center of the plane apart for repairs if something goes wrong.