Takeoff Distance

[13brv3]

This week I did some half flap takeoff in the Onex. It's clearly off the ground a bit sooner, but I'd guess only by maybe 75 ft. It's not something I'll do much, but it certainly is convenient if you want to do some touch and goes with only half flaps. I find the flap handle fiddly, and somewhat awkward to deal with when trying to keep the tailwheel behind me.

I also did some Google Earth measuring. With no flaps, just letting it fly off, I'm off the ground in 500 ft. Of course this isn't apples to apples, since I have a 912UL (80HP) rather than the Aerovee. My prop is set to a climb pitch, and density alt has been around 3500 ft, so it could be off in less than that under better conditions.

Cheers,
Rusty

[pilotyoung]

I need to get some lessons from you. I can't get off the ground in less that 1,000 feet in the summer heat. I am going flying in the morning and I will note the density altitude and what the takeoff distance is.

[13brv3]

As I mentioned, I have a 912UL engine, so it's not a direct comparison. The geared 912UL will have more thrust than the direct drive VW. BTW, I also have the short wingtips.
Rusty

[pilotyoung]

I flew this morning and the DA was about 2800 feet. With or without flaps, I get flying in about 1,000 feet. No way I could do it in 500 feet.

I did not think about the geared engine. The HP is rated the same. I have short wing tips.

I did not buy it to be a short field airplane so I just have to remember that. I love the airplane but I wish it had more power. If I win the lottery, I am going to put a 912ULS on it.

Thanks for the information and help.

[Onex107]

My Onex is ready to fly at 60 - 70 mph. Stall speed is 45. This happens in 4 - 500 ft. I'm running the recommended 54 X 44 wood prop from Sensinich and seeing 2900 plus rpm at takeoff increasing to 3000 and 80 mph on climb out. Your wings are only one foot shorter. I'm surprised they would make that much difference

[13brv3]

Since I've been playing with video, and overlays, I posted this partly as a test. I just let it fly off here, but I'll try raising the tail early and see if that shortens the distance when I get a chance. The PAPI lights on the left are the best reference point I see. This was not a max effort climb speed.

https://www.youtube.com/watch?v=I0Dwx7Dah84

Rusty

[pilotyoung]

Now I am jealous of both your flying skills and video editing skills.

I went flying again this morning. I have been testing setting the trim farther back to see if that makes a difference and it doesn't seem to make much of a difference. I just can't get it in the air before 1,000 feet. I usually get about 3100 rpm on the runway and about 3200 as I climb.

[13brv3]

I was wondering about the health of your engine. Are you using the same 54x44 prop 107 mentioned? If so, you're getting more RPM, so you "should" have better performance. If the prop is different, maybe that's part of it?

I will say that Sonex seems to publish realistic specs, so if they say it will do it, then you can probably bet money that they really CAN do it.

Rusty

[pilotyoung]

I did a top overhaul last fall. It flys well, cruise speed is what they advertise and I think it is the standard propeller. I was just trying to think of anything else that would make the takeoff distance longer. I am within the 950 pound limitation.

[13brv3]

In thinking about this some more, I looked at the Onex specs page, and they actually list the takeoff distance at 400ft...

I'm wondering how much difference there is in the attitude on the ground. The tailwheel Onex can't make a true 3 point full stall landing. Full stall is 1 point followed by the front two. If you think about takeoff performance, you can't pitch up any farther than how it sits on the ground in a taildragger, so you won't be able to fly off at the lowest speed the plane will fly. I have the slightly larger 5.00-5 tires, mostly to give about 1" more prop clearance. I've had 3 tailwheels, currently using a 4" full swivel. I haven't been able to get close to full stall 3 point landings with any of these configurations.

The other thing I wondered about is tri-gear planes. It may be that a tri-gear has more room to rotate on takeoff and landing?

Rusty