Fuel tank mounting

Thanks Getback!!  Thats what I was after. Just someones seen it done before and that it seemed to work ok. Thats enough for me to give it a go. I just wanted to check if there was any precedent etc....  Sound good. I would expect it to work. But happier to give it a go now!

Thank You.

Yabby

My go-to solution to reinforce cutouts in balsa load bearing parts  is to soak the edge/rim of the cutout in CA glue, and/or add a thin plywood doubler just around the cutout (plywood has perpendicular grain orientation in its each layer and therefore less prone to cracking than balsa) . E.g.  whenever I screw control horns on thin control surfaces like elevators or rudders, I soak the balsa under the horn base plate in CA and add a small doubler on the other side.

Otherwise I use Velcro tape to fix my key-chain camera on the wing. The camera weighs only 9 grams and the Velcro holds it well - with some unwanted vibration compromising video quality, though-, but a thin rubber band as a life-line in addition prevents it from getting lost.

Velcro in the blast-line of the propeller may soak in castor and see its small hooks become slippery and yield the grip, so I am not sure how Velcro in such an oily environment would work out.

Thanks Andras @balogh    i am going to give the Velcro a try, but your advice on using cross grain reinforcement plates is excellent. I have used reinforcement plates above and below holes, but I never thought to run the grain the other way. When you say it, its obvious, but it would never have occured to me in a 100 lifetimes.

Your explanation will be useful to me in a number of model construction areas. Now I will think when reinforcing something with a plate about the grain direction etc. It helps more than just this issue.  

Yabby

Thanks, Yabby, reinforcing by balsa may also work, but think of the main direction of pulling/pushing forces of loads from aerodynamic forces, weight or pushrod forces etc acting to crack the area, and orient the grains of reinforcement in parallel with forces.

But sanding a shallow cavity and embedding a 0.5...1mm or even thinner plywood with CA really does wonders and looks nicer in visible locations than a simple doubler overlapping the reinforcement area. When I built my tiny Lil Spee-Dee 010 a week or so ago, I embedded thin plywood in several load bearing points then corrected material losses with fluid wood paste then sanded it flush with the surrounding balsa..worked surprisingly well.

The slightly darker plywood insets at the aileron servo and trailing edge center - and another on the wing bottom - are the embedded and flush sanded reinforcements.

Thanks for the explanation  @balogh Andras, that is really valuable information that would have been out of my scope of expertease. Thanks heaps for explaining. So many uses in modelling for this.

Yabby

Hi All,

There is a glue here in Canada, called Goop.
Basicly, a thickened contact cement, that sticks to anything clean.
$5 per tube.
When velcro fails, this is the glue to stick velcro back on.
Math from here,
Means Goop is way better.
Your results may vary,
But,
One tiny blob of Goop,
Is your friend.
Dave
P.S. I agree with everyone else here...