Sonex 759 update/takeoff

[Corby202]

I now have 16hrs on Sonex 759. The last few flights have been about getting performance figures. Today I had help measuring takeoff distances. Reasonably still day, sealed runway I took off in 150 meters (no flaps). I then tried with 10 deg flap, the takeoff was perhaps marginally shorter but not by much. The acceleration on takeoff is so quick the ASI has a hard time keeping up but It lifts off by itself around 45-50 knots. Nearly every takeoff I have done it has been from the three point attitude, a couple of times I have lifted the tail first but the directional control didn't feel great. Do most of you guy's lift off in the three point attitude??.
The best rate of climb seems to be at 70 knots (3000 rpm) where the vsi is between 900-1000 fpm on a good day. The fuel consumption from this Jab engine seems good at 14 litres/hr but with the Sensenich 60x46 climb prop the engine is not working that hard I guess.
All the temps are good, EGt's close, in the low to mid 600's. The cht's are ok, #1 runs the hottest in the air at 125, the others are low 100's ( I plan to try grinding the lip of the cowling a little on the rh side).
I am getting used to using full flap on landings, the steep nose down attitude required is still the thing I have to be conscious of. I have been getting the speed back to 75 knots turning base where I put in the first stage of flap. 65 knots just before turning final, second stage of flap. I then keep it to 60 knots until I know I have the runway made and put full flap in, over the fence at 55 knots. Do those numbers seem about right to you guy's??.
I sure am enjoying flying this plane.

[rizzz]

Hi Phil,

Your numbers are very similar to mine, I always lift the tail first on takeoff though.

I agree the directional control once that tail is off the ground feels very different from the Citabria I used fly, but I have gotten used to it.
Be careful when doing this on a crosswind takeoff though, I have discovered you need to be very quick to respond with the pedals once the tail lifts, it's quite a sudden reaction that is required to keep the aircraft straight. With the Citabria, which has a spring loaded tail wheel it was a much more gradual transition.

[DCASonex]

With the need for strong right rudder in my TD with 3300 I will select runway direction (traffic permitting) that puts the wind on the right side even if that means a moderate tail wind condition. Wind from the right with a Jabiru reduces rather than increases the need for that right rudder, and with the acceleration from a properly functioning 3300, moderate tail wind is not a factor except for VERY short runways.

David A.

[LarryEWaiex121]

David,

Agree wholeheartedly with the wind off the right side all other things being about equal.
Three years ago, I was taking off and forgot to advance the mixture full rich. You know what happened next, right?
Engine coughed, I went full rich and it caught with and immediate left turn of about 20 degrees. Apparently, the runway should have been built somewhat wider because I went off the left side (narrowly missing a runway light) but did manage to knock over the plastic com. sign with the right flap on the way by.
By now if your falling off your chair laughing, your apology is accepted, thank you very much!
Much to my chagrin, the Princess very wryly asked me if that was a "normal" takeoff? Boy, she doesn't miss a thing!


Larry
Waiex121YX, Camit 3300

[mike.smith]

I almost always take off with the tail up, and do wheel landings. I have an AeroVee and I used to have the ground adjustable Sensenich prop which never performed very well, especially on climb out, even at the finest pitch. I now have the current Sonex "standard" Sensenich prop and it climbs much better. I start out at 3,200 rpm, 1 notch of flaps, and get a climb of about 400-500 fpm at 72 kts. I burn about 4 gallons/hr at cruise, with the mixture leaned.

My 3 point landings were not very consistent, but my wheel landings are insanely consistent. I prefer wheel landings for gusty or cross winds anyway. I tend to make my final approach at 66 kts, then pull back the power and level off over the approach pavement. The plane flies in nice and flat and settles easily on the main gear. I hold the tail off until I bleed off speed, but always have rudder authority when the tail comes down nice and easy. I never bounce of float a landing this way.

[DCASonex]

Larry,

Thanks for further convincing this sometimes absent minded old engineer to stick with his Bing (no mixture control) carb. :-)

David A.

David,

Agree wholeheartedly with the wind off the right side all other things being about equal.
Three years ago, I was taking off and forgot to advance the mixture full rich. You know what happened next, right?
Engine coughed, I went full rich and it caught with and immediate left turn of about 20 degrees. Apparently, the runway should have been built somewhat wider because I went off the left side (narrowly missing a runway light) but did manage to knock over the plastic com. sign with the right flap on the way by.
By now if your falling off your chair laughing, your apology is accepted, thank you very much!
Much to my chagrin, the Princess very wryly asked me if that was a "normal" takeoff? Boy, she doesn't miss a thing!


Larry
Waiex121YX, Camit 3300