Obviously excess airspeed on final is the reason any airplane floats excessively. It doesn't matter whether it's a J3 or PP's Mooney or my P172D or a 747. If the numbers are right, the airplane will land.
Here's my example--sorry for the windiness. My pard and I bought one of the first TR182s out the Cessna factory door (advice: don't ever do that!). We had had a straight 70 182, and he was a reasonably good pilot. But within weeks of buying the TR182, he wanted to have a Robertson STOL kit installed, which back then was about $20,000 or so (roughly $72,000 in today's dollars). I balked--I couldn't see the need, nor could I afford it. The airplane already was a pretty good STOL airplane when I flew it. His reason was that he had patients he wanted to visit at their ranch strips, and he wasn't able to make the first turn off of 21 at Laramie, which is roughly 1600' down the runway--he figured he'd overrun any 2000' strip.
I suggested that before we spent huge sums of money on a STOL kit, that he should learn to land much slower. But he had that feeling that many people seem to get when they move up to a faster airplane, that it must also be landed faster. So we made an appointment for me to show him what I meant.
I cheated a little and practiced a number of landings the day before our appointed time, and what I learned was that with half tanks and just me, I could consistently land comfortably at 55 knots indicated on short final, no power. Much slower than that, and I couldn't hold the nose off after touching the mains.
The next day, we went out and I asked him to first do some slow flight. His idea of slow flight was that the stall warner would just occasionally bleep. I asked him to slow down to the point where it was on all the time, full flaps, high prop, power sufficient to maintain level flight. That brought the ASI to just barely above the bottom peg. Then I asked him to do some turns, and he did the little bitty 5 degree bank turns. I asked him to increase the bank to 30 degrees. "No, it'll fall out of the sky!" "No it won't." "Then you do it!" So I did, and of course it didn't fall out of the sky--I was feeling the stall burble rather than listening to the buzzer.
Then we went back to land, and his first approach was at 80 knots indicated. He touched right on the numbers, but even with heavy braking, we went right past the first turn off. So I asked him to make the next one at 70, and although he was reluctant, he did, but still it was too fast--right past the turn off again. Now I asked him to do it at 60. "No, it'll fall out of the sky!" "No it won't." "Then you do it!"
But instead of 60, I slowed it to 55, knowing that by now we'd burned off sufficient fuel, and he was pretty light anyway, so that we were probably lighter than my practice times the previous day by quite a bit. He really was uncomfortable--hands gripping his seat etc. "You're going to kill us!" "Nope." We landed gently, and with moderate but not heavy braking, I stopped the airplane in about 600'. We sat there for a moment. "Now you try it."
Well, he wouldn't slow to 55, but he did slow to around 65, and this time with moderate braking, he made the turn off.
Then we had a discussion about stall speed varying according to weight, 1.3 Vso on final, 1.2 Vso over the fence, etc. Nothing dramatic, just good approach and landing practices.
We didn't get the Robertson kit.
Cary