G'day Don. While I haven't retro-fitted wing tanks (yet) I will be doing so in about 4 weeks time. This is due to me taking a wood saw to my wings after a minor mishap in which the retracts folded up on landing on a strip that looked smoother than it was. (And yes, I did lose the prop, although the engine was stopped, thankfully).
Anyone want a Revmaster? Am going to a Jabiru now I have an excuse to do so. My plan of attack is to install 3, 4 or 6" Aluminium or PVC tubing, as found on travelling irrigators and the like on farms. My measurements are that a 2m length, 4" in diameter, gives me 15.7 L total, or a smidgen under 1 hours flight time a 2m length, 6" in diameter gives me 35.3L or 2 hours flying time. Ergo, 2x6" and 1x4" 2m lengths gives me 172.6L of fuel, or around 10 hours flying time. With that kind of range, if you so desire, you could only go with the 2x6" tubes and about 8 hours flight time. I would be mounting this in 1 of 2 ways. 1. install a wear strap around the tubing at the ends, and cut suitable holes in the inboard and outboard wing templates, as well as through the foam ribs. This should give the tubing plenty of support. Use the manifold at either end to provide lateral restraint. Or 2. install 6" fore and aft of main spar and 4" for of rear spar, with suitable brackets. For those who know someone in a warehouse, that steel strapping they use on pallets and such would be nearly perfect, if you could find a way to ensure the little clip will not wear loose over time (tack weld?). Disadvantages of this setup are a few. No internal baffles, so fuel surge in uncoordinated flight will become an issue. The requirement for fuel boost pumps now that I no longer have a header tank. Devising a suitable filler neck for the round tubing, although this shouldn't be that hard. Benefits of this setup, again, are a few. A dirt cheap, simple, easy to make fuel tank that gives the airplane the legs to outlast your bladder. If you install the tanks for and aft of the main spar, and you hit "something" then the 6" tubing will provide a measure of impact protection, and worst case scenario, may hold the wing shape long enough to get you on the ground, versus having a slab sided leading edge. (But how often has this been the cause of the crash? Once? Never?) While I have not measured the weight of the tubing, yet, I believe it would be a small penalty over the existing header tank, and at the same time, give me longer legs for the KR. (Oshkosh here I come?). Drawings and costings will be up on my webpage sometime soon. Cheers, Rob. Robin Wills Second Person, Pacific National KR-2 VH-OMV, Ser# N111 krvia...@bigpond.com
