Takeoff Distance

[13brv3]

That certainly makes me feel better about my 912UL engine choice. We're at essentially the same pitch angle, which will require the same airspeed to fly. This must mean that the geared Rotax is getting to the flying speed a lot sooner. It seems clear to me that a tri-gear plane will have more angle of attack available at takeoff, so it will be able to lift off sooner.

I flew the plane to 10k ft today, and it was a dog at that altitude, as expected. Does the Aerovee have mixture control? I see that they spec the cruise speed at 155 mph at 8000 ft, but that's hard to believe without mixture control (or a turbo). My best cruise speed has been 133 mph (GPS averaged) at 4500 or 5500, so those will be my best cruise altitudes. It's way less than that at 8000 ft, partly due to the lack of direct mixture control.

Rusty

[pilotyoung]

The AeroVee does have a mixture control. I have not had it above 3,500 and since my top overhaul last fall, I am running it full rich. I do not bellieve the CHT's it is showing. It a climb on a hot summer day the CHT does not get to 300 degrees. I just today received some thermal strips to put on the heads. I will then fly it and see what kind of temperatures it shows. But I am planning on flying it to Oshkosh and leaving next Friday. So I will be flying higher on the way there so I will see what kind of speeds I get.

I agree with you that a nose wheel Onex should be able to get a higher angle of attach and take off in a shorter distance. I plan on asking some questions about this at the Sonex Open house on Sunday.

Your thoughts and a recent talk with another experienced tailwheel pilot have given me clarity of tought about the takeoff and landing in the Onex that I did not have before. Thank you for that.

John

[13brv3]

It's been an interesting topic that I've just never really thought about, so I've gained some clarity as well. When I started the project, I seriously considered the taller landing gear that O'Keefe can make, but the ETA would have been longer than I was willing to wait, so I settled for a shorter prop. Now I'm seeing that the taller gear could help with takeoff and landing as well, by bringing the plane closer to full stall attitude. I may consider going to the taller gear in the future.

Good luck on the Oshkosh trip. Flying into that sort of chaos is my idea of hell :-) Where are you flying from?

Rusty

[pilotyoung]

I'm from Birmingham, AL. I keep my airplane at Shelby County Airport, just south of Birmingham. I have flown into Oshkosh about 15 times. It is a stressful flight on the arrival. My plan this year is to hit Ripon at 7:00 a.m. Sunday morning. The arrival opens at 7:00 a.m. and so there should not be a lot of traffic right at the start. I want to have my Onex at the Sonex Open House on Sunday and then participate in the group taxi from the Sonex Factory to the Homebuilt Parking Area.

Our discussion has help me realize the reason why most of the time I land tailwheel first. Now that I understand the reason for it, I am going to work on wheel landings and see how I like them.

[13brv3]

You're not too far away.

I don't like normal wheel landings, and totally avoid them since I only have about 4.5" of prop clearance. I've always landed at what I call a tail low wheel landing. For the Onex, I have a good mental picture of where I should see the runway in the windscreen when I'm on the ground, and just above the runway, I hold that position and just let the plane sink to the ground. If you hit it right, it's a 3 point landing, though not nearly full stall.

Rusty

[pilotyoung]

I have 7 inches of prop clearance. Today I did 4 full stop landings trying for wheel landings. I am concerned about getting it too far forward and hitting the prop. The first one was a good wheel landing. The other three were like you described, I did not let the nose get above the angle where the airplane sits on the ground. They were pretty well 3 point landings.

I read on the EAA site the other day that you should have 9 inches of prop clearance. But my airplane is built according to the plans, so Sonex must have decided that 7 inches is OK.

[GraemeSmith]

I am concerned about getting it too far forward and hitting the prop.

Get someone to pick the tail up (only weighs about 25lb - right?) while you walk around front and OBSERVE just how pitched forward you have to be to get the prop remotely close to the ground. It's a significant angle. Even allowing for the gear spreading if you land firmly - you have to be really far pitched forward to get the prop in trouble. A level or even slightly pitched forward wheel landing is just not going to do it.

[13brv3]

I've seen that 9" figure too, but I don't know where that came from originally. I wouldn't worry about 7" in level attitude, and it pretty much fits with what I measured. My notes say 4.5", but I have a 60" 3-blade prop rather than the normal 54".
Rusty

[GraemeSmith]

OK - I went and picked the tail up today.

Legacy Sonex
Aerovee
Prince P Tip 54" diameter
Gear "relaxed".

With the plane level/very slightly nose down like you might contact for a wheel landing - tip clearance is 9 inches

With the plane in an exaggerated 7 degree nose pitch down like "driving it on" there is 7 inches of clearance.

For guidance only - your plane may vary.

[grum.man]

Last night there was a webinar on rotax installations in Sonex aircraft. Pretty good info and I guess I never realized how much more complex that installation would be. I brought up the question on whether they would offer a taller gear for rotax installations so more appropriate propellers could be used and to get a more favorable angle of attack. The presenter seemed to be a little irked by the question. His stance seems to be that visibility should trump takeoff distance and slower landing speeds. My take is you are trading one advantage for another. I personally would rather accelerate and slow down in the air not on the ground. When they brought up a comparison chart of all the engine options it made the VW seem competitive even though their numbers seem to be a bit of a stretch. They left off takeoff distance but he later acknowledged the rotax did noticeably out perform the other options even with the short propeller.