Comment

Comment by Tony Renshaw on October 25, 2023 at 6:24pm

That’s a beast of a plane Ken. Thanks for the info, it’ll help with my build.

Comment by Kenneth Clayton on October 25, 2023 at 6:02pm

Hello Tony. The engine and prop choice is what I wanted. It is the only 750SD with that size engine and a constsnt doeed prop.
From Canada. I bought Aero Sport Power IO-375, 195 HP. From Germaby I bought MT Propeller with a three blade. 58", constant speed prop. The prop is electric because an oil-hydraulic will not work. The engine is mounted a few inches ftom the firewall, so no room for sn oil filter or hydraulic governor.
The instrument panel came out at 20 pounds, which is heavy too. Weight was not 1100 pounds per Zenith specs, 1253 pounds for my choices.
A plane can fly nose heavy but the penalty is speed, increased drag, and fuel consumption. The elevator must deflect air flow to add a down force to maintain level attitude. I considered trimming versus ballast weight. With ballast, my weight and 30 gallons petrol makes the ballance at 24.6% MAC. 25% MAC is the sweet spot, and neutral elevator deflection. At low airspeeds, I will have significantly better elevator control authority. I still like my choices.
Having that said, I need to go on a diet and loose some body weight. I am a retired aerospace engineer from Lockheed Martin.
With best of luck. If you discover the perfect choice then please let me know what that is. With best regards. Cheers...

Comment by Tony Renshaw on October 25, 2023 at 4:14pm

Hi Ken,

I am already starting to think about my balance with my Rotax 914 engine, and which prop to use. Its been suggested to keep more weight up front to be able to better utilise the storage in behind the seats, but trying to avoid the dead weight issue. What engine and prop are you running, and would there be anything you could have done differently to avoid the tail weight issue? 

Comment by Kenneth Clayton on October 15, 2023 at 12:36pm

A total of 15 pounds of lead ballast installed in rear fuselage.  This was necessary because of the engine and propeller weight.  This permanent ballast brings operating MAC to 24.5%.