Takeoff performance

[AlexZ]

Hi All,
We have a Sonex taildragger with an Aerovee 80HP engine and the recommended propeller, Sensenich W54JV5L-44G.
Operating from hard surface isn’t a problem. The takeoff en climb performance isn’t what we expected, but okay for that. Since a few months we moved to an airfield with grass runways. Although takeoff is within limits the airfield operator finds that our takeoff roll is too long. The runways are about 600m(1900ft). We need about 400m(1300ft) to get airborne followed by shallow climb. I can understand that this doesn’t look to good from the tower. We don’t like it too, but if you know what to expect it doesn’t scare us.
Before we moved we already put on bigger tires and tail wheel. We're running on Mogas, so we loose a few HP. Takeoff is with 10 degrees flaps, just lifting the tail and let it fly off.
Are these numbers 'normal' for an Aerovee powered Sonex or could it be better?
What can we do to improve? Personally I think putting on a climb prop.

[tx_swordguy]

You say we if that means you are flying dual and at max TO weight I would not be concerned. If you are making full power you will only get what you will get. It is NOT a stol plane so don’t expect it to be. The 80 hp vw engine is the smallest that plane is designed for. There are ways that help getting off short fields. If you get off the ground early as possible but allow airspeed to build by staying 3-4 ft off the ground. Then start your climb as late as possible helps. You don’t say if you have obstacles you have to avoid. If you feel comfortable with it I would not worry. 1900 ft grass in a sonex is a fairly short field in my opinion.
Mark

[tx_swordguy]

The climb prop would help some but it won’t make hp. Not saying don’t do it, just saying know what to expect. The climb will be somewhat better but you will loose a couple mph at cruise along with possible over speeding the engine in a WO level run. Essentially you will reach your cruise rpm at an earlier throttle setting which will probably be at a slightly lower airspeed. You won’t go from 300 fpm climb to 2000 fpm by just adding a climb prop. As long as you realize that you will be fine

[MichaelFarley56]

Alex, your numbers seem fairly typical for an AeroVee powered airplane operating off grass. If you have a moment, let me ask a few questions.
- What RPM do you see in the takeoff roll? Hopefully you’re getting at or over 3000 RPM (3100 or more would be better)
- At what weight are you departing? Adding a passenger makes a big difference.
- Do you have all of your gear and gear leg fairings installed? That normally affects cruise more but can still have an affect on climb.

I agree with Mark; these are not meant to be STOL airplanes. You may be able to purchase a different propeller with a little less pitch for better climb rate but cruise will suffer. That’s your decision.

Best of luck!

[AlexZ]

'We' is me and my co-owner.
- With both of us in the plane we're at gross 1100 lbs.
- We get over 3100 rpm in takeoff, so the engine is developing the power it should have.
- Only the wheel pants are missing.

Conclusion for now is that our Sonex is performing as expected with the Aerovee.
Our main concern is the takeoff roll. The runways at our home field EHHV are short, but fly out is without high obstacles. In one direction, 07, the climb out is over trees with no options to land other than in the trees.

For now we're going to try a climb prop. We're going to loose some in cruise, but a shorter takeoff roll is of more importance now.

Thanks for the comments. It helps.

[gyroron]

Your TO might be slightly shorter if you hold it in the 3 point position till it flys off on its own