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Old 03-14-2010, 07:56 PM
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hyperdyne
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Default RE: Old JHH F-4 airframe conversion

Ravivos, thanks much! I tried to maiden her yesterday but the steering was jacked up (the push-pull cabling was getting hung up). Plus she was really sensitive to steering input. After fixing all that I tried again and it ended up spinning out and going off the runway. I have never seen a plane do a doughnut before! Had to fix a bent gear and found that the dual wheel nose gear was slightly crooked and only engaging one wheel on the ground normally. I think this may have something to do with it. Plus I was (purposefully) quite nose heavy with a full load of fuel, this may have made the issue worse. So back to figuring that out.

Anyway here are a couple pics of my install. This was the first jet I actually built from just a body and a few installed pieces. So it was a learning experience figuring out how to install and fit everything, getting it to balance, etc. Plus there just isnt a lot of others out there with build logs on this plane.

I ended up putting much of the equip in the cockpit area. The biggest decision are the fuel tanks. They will really only fit right in front of the intakes. After much trial and error, I was able to get a dubro 50 oz. + a dubro 16 oz. to stack on top of one another and fit perfectly in the area behind the cockpit. This gives 66 oz of fuel capacity which will be great for a 14 lb turbine!

The UAT and fuel pump are right in front of the fuel tanks. All electronics and gauges are up front.

For CG reasons, I ended up putting the system battery and receiver battery in the engine bay. I am using a 15amp BEC to run all the servos. The retracts are air up/spring down. A simple robarts valve with flow adjustment is what I used. Both air tanks are also in the engine bay underneath. If you can find the small silver robarts tanks these fit perfect in that area. For some reason the white tanks are a tad longer and wont fit without cutting the spar (didnt want to do that). I ended up using a jettronic valve and BVM 2.25" sport wheels and brakes for the mains - they work great (the same one listed for the yellow F-4).

Dry (but with UAT filled) the plane CGs perfectly at the 9" mark. With full load of fuel she is nose heavy but hopefully from what I have heard doesnt change the performance that much. Plus I want to be nose heavy on most of my jets. I also have a CG excel worksheet if you need it (got it from JPO site and filled it in).




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