Do airplanes tend to float when landing in cold weather?

[snopercod]

Thanks to all for your comments and I've learned a lot about reduced drag/increased lift in ground effect and increased power in cold weather. But now I see this thread moving away from the original question into "Lancair Landing Techniques". I'd certainly be glad to discuss that, but an RV forum really isn't the place. The management has been gracious enough already. Thanks again.

[F1R]

Originally Posted by snopercod

Thanks to all for your comments and I've learned a lot about reduced drag/increased lift in ground effect and increased power in cold weather. But now I see this thread moving away from the original question into "Lancair Landing Techniques". I'd certainly be glad to discuss that, but an RV forum really isn't the place. The management has been gracious enough already. Thanks again.

In cold air , since the air has more O2 in it, you are effectively making the mixture leaner. I have not read to see if your ship is injected or has a carb.

If injected, your normal idle rpm will be faster as it is like the 50 RPM gain as you pull the mixture half way out , but from the cold air.

If carbed, try landing with full carb heat as that will richen the mix and drop your RPM just a bit.

If that does not do it, just pull the mixture all the way out and try holding the mains 2" off as long as you can. In order to do this you will be progressively increasing the AOA and raising the nose wheel ever so gradually while holding the mains off 2" until stall.

[snopercod]

Originally Posted by F1R

If carbed, try landing with full carb heat as that will richen the mix and drop your RPM just a bit.

Yes, my O-290-D2 is carbureted. I'm becoming convinced that I float more during cold weather due to the excess power the engine is putting out. So pulling carb heat and leaning would help counteract that. When I pull carb heat during runup, I get roughly a 250 RPM drop so my setup works well. The only concern I have is that if I had to go around, I wouldn't want to forget to remove carb heat; I made that mistake once as a student pilot and almost had a close encounter with an apartment complex so it's burned into my brain.

I'll go up and practice that.

[RV7A Flyer]

Just curious...taking the AOA indicator out of the equation here, just what IS Vs0 (demonstrated via actual full-flap, gear-down stall at altitude)?

Forget the 82 KIAS for the moment...are you *sure* Vs0 is as high as you think it is?

[F1R]

I'm just reading through earlier posts on this thread. I approach at 62 to 65 Kts in a heavy fat IFR F1 Rocket. Yes that makes for a steep approach but I have enough airspeed left to round out and flare. Your IAS of 78 Kts in a 7A would instantly explain why you float down the runway. I think you are carrying way to much air speed and energy. I think the simple solution is to ride with some other 7A guys that operate out of short strips and just watch their numbers and see how it looks. It will be steeper and much slower.

[RV7A Flyer]

Originally Posted by F1R

I'm just reading through earlier posts on this thread. I approach at 62 to 65 Kts in a heavy fat IFR F1 Rocket. Yes that makes for a steep approach but I have enough airspeed left to round out and flare. Your IAS of 78 Kts in a 7A would instantly explain why you float down the runway. I think you are carrying way to much air speed and energy. I think the simple solution is to ride with some other 7A guys that operate out of short strips and just watch their numbers and see how it looks. It will be steeper and much slower.

He's already said he's flying a Lancair, not an RV.

[F1R]

Thanks! That explains a lot.

[snopercod]

The weather has been crappy so my landing-speed-quest was interrupted for a couple weeks. I went up today (OAT=45F) and flew wind triangles at 80 KIAS to verify my pitot-static system at that speed. I averaged three runs and as near as I could tell, my ASI was right on. The formula I use is very sensitive to ground speed so it's possible that there was an error of +/- 1 Kt but that's plenty good enough for me. I tried to land at 78 KIAS today but a gust of wind on short final bumped my speed up.

The important thing I learned was that pulling carb heat on short final had absolutely no effect on my engine RPM. It read 1030 at idle with or without carb heat. I take that to mean that the prop is driving the engine at 85 KIAS. Now that the weather is better, I'll continue testing and report back.