Do airplanes tend to float when landing in cold weather?

[snopercod]

Today I landed at AVL in 0C weather and once again I floated several thousand feet before touching down. It was very frustrating but she just didn't want to land. Before taking off my idle speed was 830 RPM where on a warmer day it would have been around 700. So more power at idle must be part of the problem. My IAS was right on the normal 80 KIAS, but when I flared, she just kept flying....and flying...and flying. A gust ballooned me up off the runway, my AoA was going off, and I had to add power lest I stall and the runway rise up to smite me. I was all set to go around but, after easing the power back off, gave it one more try. Amazingly, the bi*ch finally touched down 4,000' down the runway. Sheesh... Two years ago I checked the calibration of my ASI, but I intend to do it again when it's cold and see if it's different. Here's the embarrassing video, along with my "good as it gets" landing at GMU 1 hour prior. The only difference that I could see was that the OAT was 40F at GMU vs 30F at AVL. Ground speeds were similar and headwinds were ~5 Kts. at both airports:

Floaty 30F landing at AVL

Normal 40F landing at GMU 1 hr earlier

[N62XS]

Airplanes float(fly) until stall speed is achieved. Ground effect has a bit to do with float, but if you slow down, it will land, hot or cold.

[ChiefPilot]

Originally Posted by snopercod

My IAS was right on the normal 80 KIAS, but when I flared, she just kept flying....and flying...and flying.

An 80kt Vref? You might explore a Vref based on 1.3 times your stall speed and see how that works. A typical Vref for my -6A is in the low 60s, sometimes upper 50s if I'm light (computed using a TOLD app I wrote for my phone/iPad).

[snopercod]

Originally Posted by ChiefPilot

An 80kt Vref? You might explore a Vref based on 1.3 times your stall speed and see how that works.

That would be 78 KIAS, which is just about what I was indicating. The Lancair is different than the RV in that it develops a high sink rate between Vref and Vso. I try to avoid that regime until the wheels are <6" above the runway. I guess you watched the "good" landing using the same airspeeds. I'm still searching for an explanation why that one worked and the colder one an hour later was ugly.

[gammaxy]

Some people might not be seeing the good landing because the URL is missing a ":" after the https.

https://www.dropbox.com/s/5kj6n1xzsv...nding.mp4?dl=0

I try to fly the same IAS on final during all temperature conditions I've flown in from ~15F to ~105F and I've never noticed any increased tendency to float when cold. Even if temperature had a significant aerodynamic effect on float, 10F is pretty insignificant.

My impression from the video (based on little knowledge of your airplane) is that you are flying the approach too fast even in the good video. You round out and fly down the runway at least 500 feet and still touch the nose wheel simultaneously with the mains. In planes I'm familiar with this is at least several degrees AoA below stall. It seems you are carrying more energy on final than you need. Forgive my ignorance if this is just how you are supposed to land a Lancair.

If it were my plane, I'd make sure I know exactly what the stall speed is at different flap settings and start flying my approach slower 5 knots at a time until I feel like I have just enough energy to flare and feel for the runway for a comfortable (not too long) amount of time. I'd probably try practice landings a few thousand feet AGL at these reduced speeds to build confidence.

I imagine this speed might end up being lower than you currently feel comfortable with if you start consistently touching down close to minimum speed on the mains with the nose wheel off the runway.

Also, I'd try to fly the approach aiming closer to the threshold so I'm not flaring ~1000 feet down the runway.

[snopercod]

Chris-- Thanks for your constructive criticism and fixing the link. I'm not sure how the ":" went away on a cut-and-paste.

[flyboy1963]

well John, since you posted on a public forum, you get the whole enchilada!

as others have observed, we are mostly not Lancair drivers.

Is there another notch of flap to be had? that's usually the 'drag' that would reduce the float.
If you are carrying power to flatten the approach, as you say the sink rate is dramatic, you have to bleed off all that energy.....= float, or just plain flying level in ground effect.
If your idle is higher in cold temps, you have a rich mixture. Try leaning if you can ( FI not applicable).
I saw the nose pointed at the aim point on the runway....I never saw a 'flare', which dramatically increases drag, with minimal lift, at or near the magic number ( stall),

If you have an AoA, you can practice all this at altitude, then try above the runway, where you might have to add another 'dot' or two to your pitch.

I find speed, sink, and float a big issue with my RV-9a, all of which can be addressed...I too am learning on every landing, and if I fly the correct speeds and pitch on the approach, the landing is guaranteed to be a good one, on the mains, stick in the belly, minimal tire wear etc etc.....all good stuff.

is there a transition trainer on the Lancair? I'll bet one circuit & landing with them would answer a lot of questions.

enjoy the cold 'n clear while you can!!!

[snopercod]

Originally Posted by flyboy1963

Is there another notch of flap to be had?

Nope. What you saw was all I have: 20 degrees. Later model Lancairs have 30 degrees. Maybe it's not a coincidence that the L-320s do better at landing on the mains. As you saw, I always do "three point" landings. There's no "flare" like one would do in a Cessna. I land the Lancair just like I would a floatplane: Hold a level attitude just above the surface, ease off the power, and let it settle. Normally, that all happens immediately after round-out, but as you saw, it sure didn't this time.

Originally Posted by flyboy1963

If your idle is higher in cold temps, you have a rich mixture.

I've set both the idle speed and mixture, but that was done when the weather was temperate so maybe I need to re-do it when the weather gets cold?

Originally Posted by flyboy1963

If you have an AoA, you can practice all this at altitude, then try above the runway, where you might have to add another 'dot' or two to your pitch.

I have an AFS Sport system and it works really well. I just uploaded the cockpit video of the same landing so you can see/hear the AoA in action: Cold Weather Landing from Cockpit Cam

The landing gear in a Lancair isn't nearly as robust as in your RV-9. The wheels are tiny, there's only maybe 3" of travel in the stuts, and the last thing I want to see are the gear trunions breaking through the top of the wing skins if I drop it in from 24".

Originally Posted by flyboy1963

I fly the correct speeds and pitch on the approach, the landing is guaranteed to be a good one

That's my belief but I'm still missing something. In the above video I had a stabilized approach at 82 KTs, which was maybe 2 Kts too high. I held in the usual tiny amount of power, but I'm now thinking that was too much. Doing the math, it looks like on a zero-degree day my engine would put out roughly 5% more horsepower power than on a standard day. That's something I haven't been considering, but will in the future. I'm still learning, obviously.

Originally Posted by flyboy1963

enjoy the cold 'n clear while you can!!!

I DO really like climbing out at 2,000 fpm on 140 HP!

[ChiefPilot]

Originally Posted by snopercod

That would be 78 KIAS, which is just about what I was indicating. The Lancair is different than the RV in that it develops a high sink rate between Vref and Vso. I try to avoid that regime until the wheels are <6" above the runway. I guess you watched the "good" landing using the same airspeeds. I'm still searching for an explanation why that one worked and the colder one an hour later was ugly.

Sorry, video link didn't work on my phone and didn't realize you weren't in an RV, so i totally get the 80kt vref with a lancair.

[RV7A Flyer]

Originally Posted by snopercod

As you saw, I always do "three point" landings. There's no "flare" like one would do in a Cessna. I land the Lancair just like I would a floatplane: Hold a level attitude just above the surface, ease off the power, and let it settle. Normally, that all happens immediately after round-out, but as you saw, it sure didn't this time.

I don't know Lancairs from my @ss, but I was taught never to land in a "three-point" attitude in a nosegear airplane. Mains only, hold the nosegear off, and then let it come gently down as elevator authority is lost.

Perhaps that (you're not reaching critical angle of attack, despite whatever your AOA is saying), combined with this:

I held in the usual tiny amount of power

is the root of the problem here? I believe I can *hear* the alternator whine decrease *after* you touch down, rather than before (in what should be the flare)? If you're trying to *land*, power above idle is working against you.

Basically, you're flying it onto the runway, rather than doing a proper flare and stall at 1-2" above the ground, under idle power, perhaps?

ETA: It's been ages since I got a seaplane rating, and never really used it, but I don't think they taught a *level* attitude during landing due to the possibility of the floats "digging in" and flipping the plane. It was always a nose-up attitude and then after landing, stick full aft.

I'd worry much more about the nosegear hitting *first*, causing porpoising and PIO, than I would flaring too high, unless the airframe and gear are considerably weaker and more fragile than I would expect in a properly design light aircraft.