The goal is to acheive maximum static thrust while still being able to maintain a decent cruise speed.

Once my Ragwing Stork is completed it will be my leisurely daily flyer but I would like to be able to repitch the prop and pull it onto the line for STOL contests also....

I've been using a prop calculator but I'm getting some conflicting #'s when plugging in the data.

I understand a small prop gives speed and a large prop gives thrust.....but with a in flight adjustable prop you should be able to find a good compromise between the two....it's not adding up that way though.

Here's the specifics .......

Ragwing Stork : 500 lb empty weight..I weigh 220 lbs....fuel 5 gallons when competing.

Cruise speed should be around 75 mph.

Rotax 670 engine : 100-103hp....Rick claims an honest 100 hp and Mike says another 3 hp with his custom pipe.

6500 rpm max.

E gearbox : ratios 2.68 - 3 - 3.47 - 4...maximum diameter allowed is 72".

Prop : Ivoprop 3 blade.....ground adjustable or in flight adjustable.

The problem that I'm having is I can get 500 - 600 lb static thrust but the cruise speed suffers.

Or I can get a decent cruise speed but static thrust suffers.

I've played with the numbers trying to find a happy median but things start getting weird.....

With an in flight adjustable prop...increasing the pitch does nothing for the cruise but raises the hp required...what's up with those numbers?

I understand you need more hp for pitch but I don't understand why the cruise speed doesn't increase with the pitch change.

Is the calculator not taking into account for the prop unloading with airspeed ?

I'm also finding that the 2.68 gearbox ratio is giving me better numbers than the rest.

Kevin