Gyro , do you think the CG and F33 would have worked on your plane with a heavy tail such as on the Himax originally? Your videos are impressive!

textailwinds,

I have some experience with a stock 1100r with heavy tail powered by a hirth f33, we had to put 30lbs of lead directly behind the motor to get the cg within limits. Plane flys good but the extra weight would have been better used to generate extra horsepower. Other than the added ballast, the plane meets part 103 requirements.

Chris

could you move the motor forward? build the light tail?

I found out  from a Hirth distributor
that the F33 is now a single
Ignition and plug engine with
a new head available. This extra
2 lbs. on the engine helps with
a bad vibration below 2,000rpm,
and allows the motor to run cooler.
Adding weight for the CG, is not
what we want. As noted by Bluemax.
I see why we are trending back
to VW engines. I put the Eros nose
on my project. It looks to me like
it could accommodate a 1/2 VW
with not to much effort. The fuel
burn would be low. And the cost
would be $3000.00 less than the
next size up Hirth.

Textailwinds,

I own a F33 powered frankenmax, a 1600cc VW powered Vmax, an A65 powered pietenpol,  and a 503 powered flightstar. Of the 4 planes, the Vmax is the only one where the cost of engine parts doesn't scare me..... It would be followed by the 503, F33, then A65. If a F33 suffers a seizure, it will cost roughly $1000 from a hirth dealer to get a new cylinder and piston. I asked recpower about getting a service manual for the engine and was told they woudnt sell them as they didnt want anyone besides a licensed hirth dealer working on the motor. I couldnt even get them to provide the ignition timing settings to me......

I wont  own another hirth for the above reasons, its a powerful little motor for its size but the folks at rotax service centers are far more willing to share service information with their fellow aviators.

Chris

I had to add about 30lbs to the nose of my max to balance with the F-33 and that was with the larger head I added to keep the CHT down. I remember doing the math and moving the F-33 forward to balance was not feasible.

Ended up replacing the F-33 with a Kawasaki 440A and that balanced well.

Textailwinds,

I wonder how well the new single ignition F33 performs? My dual ignition engine wont turn more than 4800rpm with one side of the ignition shut off.

Chris