I was looking at this picture thinking, “wow, nice job Matt, the way you captured all the bugs and scratches on the wind screen, beeeaautiful”. Then I remembered where I took this, and why it was funny to me. Look at my GPS, and notice the ground speed, 29 mph. N7780Y cruises at 90 mph in dead calm air at 2500 RPM. I think the wind was blowing 50-60 mph at altitude. The air-strip I was heading for was on the valley floor so it had good approaches from both directions and I had a sneaking suspicion that it was not blowing as hard on the ground. I landed several times here on this particular day and it was never blowing more than 20 on the ground.
For those that don’t fly I am going to briefly explain the difference between airspeed and groundspeed. If my airspeed in flight is 100 mph and I am flying into a 100 mph headwind then my ground speed is 0 mph. That’s all, it’s not rocket science. Airspeed is all-important when it comes to the flight of the aircraft because it’s what keeps the plane in the air. It’s also what all of our structural limitations are based on for deploying flaps, maneuvering speed, Never Exceed Speeds, etc. Groundspeed is what gets us home in time for dinner. Pilots often ask what airspeed I land at in the cub. I have NO IDEA. I honestly don’t know, I have never looked at my airspeed indicator on landing because I don’t care. I can feel it in my butt like all the other guys that fly cubs. I just fly it as slow as I can behind the power curve so I am hanging on the prop a bit.
Here is my point after saying all this … I ALWAYS LOOK AT MY GROUNDSPEED on final. I know that is bassackwards from how we were taught because the aerodynamics of the plane don’t care about groundspeed, and if you have a tailwind you could stall and crash. A well-tuned Super-Cub-Butt should be able to feel a 3 mph tail-wind. If I see my specific magic groundspeed, in landing configuration, on final, I know I can get my plane stopped in the given distance. (NOTE: I did not put numbers in that last sentence because I don’t want some idiot to sue me when he/she crashes using them.) All I am saying is that I feel my airspeed, but I visually check my groundspeed, because groundspeed is the energy I need to dissipate upon touchdown. I did not always have a GPS so I certainly don’t need it, but I sure do love double-checking that ground speed. On numerous occasions I have used that information to get out of bad approaches on one-way strips before it was too late. If you’ve ever landed on the side of a mountain with a 8 mph tailwind you overlooked then you know what I am squawking about … ya’ that’ll make your butt pucker.