Hi F104 pilots

My F-104 is nearing time to take to the sky, turbine power... lots of on-board fuel. How much CG shift is acceptable without compromising the aircrafts stability.

I'm told by a reliable source that the 104 is very tolerant of forward CG shift, can it handle a bit of reverse shift? if so, how much in each direction?

I would like to carry about 2.5 liters of fuel on takeoff, and can get the CG correct by having tanks in front of the inlet ducts, and a set of large saddle tanks behind the motor. I intend to empty the saddle tanks first, meaning that the CG will move forward during flight until the main tank in front starts emptying... & the CG starts returning to approx. the correct value on landing - but have to allow for some spare fuel on-board.

Any ideas?

TIA
Gordon.

Hi, I have 94oz of fuel between the inlet and no saddle tanks. Never had problems taking off or landing. I did have to hold some up elevator to maintain forward flight until some fuels are burnt off.

Hi,

I use the Avonds' recommended set up of 2 x 11 oz saddle tanks in the engine bay and a 50 oz tank between the intakes. I balanced the model with tanks empty, meaning it is well nose heavy when full but there's no problem with tailplane authority on take-off and, apart from a gradual nose up trim as the fuel burns off, there's no noteable effect during flight either. It's a very tolerant aeroplane, all round.

Cheers,

Dick
England

Hi guys

Thanks for your input. I had my maiden flight on Sunday with the F-104. CG for takeoff was as recommended, magic rotation, moving forward by 70mm during flight until the rear tanks are empty, then moving back about 50mm, landing slightly nose heavy.. no problems here.

Very impressive presence in the sky.

TJT3000 motor, JR radio.

BRG
Gordon.