Mike Kovacs wrote: >I have a hard time keeping the glider from stalling >when it turns back into the wind and losing a great >deal of altitude. I have even reverted to watching >the vultures fly in the wind. I see what they are >doing, but just can't seem to do it. It looks as if >they use their downwind speed to gain the altitude >lost when they turn back into the wind. I seem to >have to keep my speed up on the downwind, but just >lose too much . Mike, this is a very good question for a new pilot, and even for us experienced pilots to review. There are many approaches and each pilot will have his/her own technique. I will give my opinions here and other will add some with their experience. The approach to thermalling in the wind may depend on many factors: wind speed, characteristics of the plane/airfoil, control surfaces with plane responses, land characteristics ( wave production, trees etc), where you are flying (upwind or down wind from your position), and your experience. Blaine Beron-Rawdon has written about plane flying speeds in windy conditions, as perhaps many others. I view the plane circling in the wind. The plane looks like it is flying faster downwind versus upwind because we use ground based objects as a reference. Going upwind, the speed we observe is the plane's flying speed minus the windspeed. Going downwind the plane's speed is the flying speed plus the wind speed. Often times, we think that we need to slow down the plane going downwind in order to reduce the sink rate. However, we often have to give down elevator to speed up in order to get the surfaces of the plane working better to get it to turn. When we turn back into the wind the plane is often going faster than it needs to go to remain in level flight going upwind, hence the plane balloons up and we feed in down elevator. We can take advantage of this later. This is a short explanation but is sufficient. In practice, we can fly either in circles, or we can fly in an S pattern, always turning upwind. The latter flying is like a flying on the slope and allows you to never really gain speed or loose control. While the addition of ballast helps with penetration, you can add it an still have problems. The main problem I found was that in windy condition we do not have as much down elevator as we really need. For years, I used to fly in the wind by just adding an oz of lead to the nose, to move the CG further forward. My controls were better, and by not adding ballast you still have a plane that flys like it always does. Anyway, if you fly the S pattern you have to allow for downwind drift of the thermal and as your plane goes crosswind you let it drift downwind through the center of the thermal. When you exit the thermal you will be downwind of its center. When youthen turn upwind you are slightly ahead of the center yet outside of it. Then you repeat the process you go crosswind, drift through the center of the thermal. You go on with this. The advantage of this pattern is that you are nearly always in control of the plane and its speed. You can fly circles, and it this case you have to concentrate on drifting downwind with the thermal. Sometimes, if the thermal is big enough, fly in the thermal. In this case, the thermal as a whole is traveling/drifting downwind, but you see the air inside the thermal bubble. It is alot like the old question of birds flying in a Boxcar. While you are in the thermal, the air you are flying in is the thermals air not the exterior air. Really a closed system. If you are trying to fly in a small thermal in the wind, you will be entering and exiting the thermal and the air around it. In these cases you need to have either good control surface responses, or be able to "lead" you ship anticipating what it will be doing. If you fly in this pattern, you can be going upwind. Your plane will balloon up, depending on its speed and the rising air of the thermal. As it balloons up you can either give down elevator or turn the ship. If you give it down elevator the plane will be upwind of the thermal and you have to then allow the plane to fly more downwind on the downwind leg before you turn it upwind to get back into the thermal. If you turn yo convert the energy of balloning up into altitude, at the expnese of flying speed. As you reach to top of the ballooning path and turn downwind in the circle, you have to add some down elevator to keep your speed up so that your control surfaces remain effective. If they are not effective you will flounder downwind with the wind and end up downwind of the thermal. You will then have to add down elevator to regain speed for the turn, or after the turn you will need to add down elevator in order to penetrate back up into the thermal. Ideally you can time the downwind leg and the balloon such that you stay in the thermal. That is the trick. I add noseweight to my plane because Ihave found that adding noseweight keeps me in flying control of the plane, makes the plane less pitch sensitive and takes away some of the ballooning. It allows me more down elevator control. Many pilots may differ in this approach, but if you do not fly with ballast alot, you will be inexperienced with you your plane responds and how fast it needs to fly with the new weight. It is a matter of preference at this point. There is also another approach you can use, and this is effective if there is some "wave type" condition. While doing the S pattern, and keeping the plane pointed approximately 45 degrees or less from the incoming wind direction, you methodically pull up elevator. That is, pulse the elevator. Pull up, the plane balloons slightly and increases altitude. You tap down elevator to level the plane and it appears that you have gone up a foot (or more), like a staircase. While the plane looses some flying speed, you have gained altitude. It is hoped that the sink required to get the plane up to normal flying speed again is less than the altitude you have gained. This works best normally with larger heavier ships which penetrate well in the wind, like F3B, and where the difference in flying speeds between the start and the top of the ballon is small. There is so much more to be said, but I hope this get s you trying some differenc techniques. Good Flying, Chris Adams RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
