This happens to me every time I fly when its windy. I get the plane trimmed up for hands off at full throttle ('cause that's how we do it 'round here) on the downwind. When I turn the plane back into the headwind, the planes seems to slow down. It takes me forever to get back to the runway.I have no more throttle so I have to deal with it. But here are my guesses as to why this is happening:

1) The aerodynamic drag of the airframe is increasing due to the headwind, thus slowing me down.
2) The headwind is causing the propeller to cavitate, thus decreasing its efficiency.
3) My turn radius somehow changed due to the wind, and while maintaining angular momentum, my speed decreased (just like an ice skater extending her arms during a spin).

I have figured out the downwind turn, but not the upwind turn.

Kurt

You're confusing ground speed with airspeed. Airspeed will remain the same whether you're going up wind or down wind. Now ground speed is the speed your airplane passes over the ground. Indeed a head wind will slow your ground speed. You very well might have to increase the throttle to increase the ground speed. Going into a stiff head head.
Me I trim to fly thumbs off at mid throttle that way I climb with power on. Trimming at full throttle when you reduce power you'll descend. Not a good position to be in when you cut throttle at the threshold to land.

Jet is correct. At full throttle you are at terminal speed. This means there is no more power available to overcome the drag at the speed you are flying. The airplane sees this speed regardless of what the wind is doing. You see the difference because you are on the ground. If after being trimmed at full throttle your average sport airplane will not retain the same trim at half throttle then it is not set up correctly. Either your decalage is off, thrust line is off or CG is off or any combination.

think of watching someone walking (at a constant rate) on a moving escalator, both in that same direction as the escalator and in the opposite direction.
when the person is walking in the opposite direction as the escalator is moving, he appears to slow down.

Great example Jim.

Bigger engine solves everything

Yes more power always makes things fly better, except if the airplane is not flight trimmed well. Then it just exaggerates the out of trim condition.

Hi5 Bozarth!

Classic troll and you set the hook deep! roflmao

Really Kurt, it's not even April 1 yet.

You were Air Force, not Navy. Air Force props do not cavitate in the air, only Navy props can cavitate in the water. Cavitation is when bubbles of vacuum form in a liquid, and we know that the Air Force only flies over water. The closest that the Air Force ever gets to water is when they get their drinks after a hard day of watching the auto-pilot.

ah, the dreaded down wind turn. The RCUniverse equivalent of the gift that just keeps giving.

I guess I don't understand the fun in trolling

I haven't looked at a lot of problematic (troll-like) threads but all in all I'd say that the down wind turn ones have been entertaining. There's actually been some good information in it; what some people have presented as "fact" supporting stuff has been interesting at times, amusing at times. Yes, at times it got acrimonious and needed to be dialed in a bit. But as long as people were able to avoid getting too nasty, I'd say it was more interesting than others.

So I can see why some don't want it to end!!! I think I mentioned that there are a couple of other basic fundamentals about flight that I'd like to learn more about. I am sure that these would follow a similar path as the down wind turn-some good information, some questionable stuff, some people taking it too seriously.

So, trolling? Maybe not 100% trolling, but something else as well. Maybe more like "gee overall this was fun. Can we keep it going?"

Downwind turn, or in the OP's case upwind turn discussion will always be with us in this hobby.

It takes two ingredients
(1) The commonly observed fact that our plane changes it's relational speed when the wind picks up and the observer isn't sure why, and
(2) a second person with a fading memory of a half misunderstood, simplified high school example of Kinetic Energy.


When those two people meet up, 9 posts later a new downwind turn discussion is born, with many well wishing relatives offering the new couple all sorts of baby advice...