Seems like many people are trying thermal sailplanes for the first time in AFPD. I've been able to ride thermals pretty well in AFPD so I'll share my experiences as just one example.

I like flying "full house" ships (both flaps and ailerons) in the 2m range. The closest option I have in AFPD is the Ventus, a 3m full house scale sailplane. (If you are listening OMP or Ikarus please add some 2m full house planes! I can't find any even in the download sites. And no elec motor please!).

CG
The stock Ventus is very stable and less responsive to thermals than I'd like. It also tends to pull up from its best glideslope instead of staying on slope. I copied the Ventus to another model name and moved the cg back to -1.75 in based on the "dive" test. It still pulls out of a dive on its own but not as bad as it used to. Move the cg back to make the plane more pitch neutral (holds a given pitch) but not so much to jeopardize control. If the plane gets too twitchy or stalls easily, you've moved the cg back too far. Elevator trim also affects this so you need to adjust both at the same time.

I'll save flaperons and landing crow settings for another post.

FLIGHT MODES (Flap settings)
I prefer to have 3 preset positions for the flaps: speed/reflex (slightly up), cruise (neutral), and thermal/loiter (moderate down). The purpose of these settings is to change the wing camber and optimize aircraft performance in each flight task. If you want to cross the field with the minimum loss of altitude, move the flaps to the speed setting. The plane's path will steepen slightly (let it go!) but it will cross the field so quick it won't lose much height. Use the neutral cruise setting to sniff around an area for lift. This setting balances altitude loss with a moderate speed to cover an area. Kick down to thermal flaps to slow down if you think you've found some lift. At the slower speed you can turn tighter to stay in a thermal. The ventus flies so fast you really need the cruise and thermal settings to slow it down to detect thermals and stay in them.

Since we don't have guages you'll have to load your plane into a *non photo scene* so you can get the camera up really close to see the flap deflection when you make your adjustments. Use the up arrow key to move the camera in close, and the left/right keys to move behind the plane. Someday I'll research the wing type and put in ideal settings but for now I set the reflex flaps to about 3 degrees up; really just a smidgen. I set the thermal flaps to about 20 deg down. This seems too much to me now but the Ventus doesn't seem to suffer from too much drag.

WHERE TO FLY
Pick a scenery that has a large open field. I often fly at "rottenburg". It is a large empty field with some light industry in the background and a very large, distant hill with a nice little house on it. I make the house on the hill my "upwind" reference. The hill is too far away to affect thermal patterns or cause turbulence in the flying area. Below I have suggested weather settings. Beginners may want to try turning off wind, but be cautioned that this makes the flying conditions unrealistic. Turn wind back on as soon as you can so you can learn how it will be in the real outdoors. The wind settings I suggest are still a "very good flying day" so the wind shouldn't give you much of a problem.

Wind: 2-3 m/s and set FROM the direction of the house on the hill (130 degrees)
Turbulance: 0.5
Thermals: anywhere from 3 (challenging) to 5 (obvious, but good for beginners)

LAUNCH
Let the plane turn into the wind while sitting on the ground. Retract the airbrake. Retract the wheel. Set flaps to "speed".

Press H once (50m challenge) or twice (100m beginner) to launch the plane. Let the plane fly away for one or two seconds, then save this position with F3. From now on just use F4 to start again. (Make sure to be in "speed" flaps each time you restart).

Fly at "speed" upwind for about 10 seconds to extend away from your pilot position. I find it much easier to hunt thermals if I can watch my plane from the side rather than from directly below.

HUNTING
Once you are in the upwind hunting area, switch to cruise or even thermal flaps. Try to trim the elevator to maintain a steady shallow dive angle. Reduce "porpoising" as much as you can. Once you have a steady glide slope, note that your plane does indeed sink slightly but noticeably. This sounds silly but it is important. In dead air, your plane SINKS. The most subtle clue that you are in or a near a thermal is your plane will MAINTAIN altitude. This is often missed by power pilots who are used to their planes flying level.

So fly back and forth across the wind, staying upwind (in the direction of the house on the hill). Sometimes you may never find lift or you'll dork a turn and lose so much altitude the game is over. F4 and "speed" back into the hunting area. Note that the plane will want to climb whenever you point into the wind. Don't confuse this with a thermal. Just continue through your turn.

UP WE GO!
Hey, did you realize that in the last few seconds you weren't sinking? Or maybe you even climbed a bit? A thermal "bump" can be as subtle as this; your plane stays level or rises slightly without pitching up. More obvious signs include the tail lifting or a wingtip lifting (don't confuse this with turbulence though). Time to switch to thermal flaps, slow down and begin circling in the area. Begin with shallow circles (30 deg bank), don't lose excessive altitude while circling. Keep a shallow steady sink to maintain airspeed. Two or three circles is all you need to detect a thermal. If nothing is found, switch back to cruise (optional) and move to another nearby area to begin hunting again.

You may notice that your plane wants to maintain or climb on half the circle and sink on the other half. Bias your circling to the "rising" side. If you move into position in a thermal you should be able to increase bank angle to 45 degrees or more, yet your plane will still climb!

Now that you are in lift, maintain a steady bank angle. The wind will want to extend your circle downwind. Let it. You want to travel downwind with the rising thermal.

Now its entirely up to you how long you want to stay with this thermal. I generally bail out at 500ft and head upwind again just to keep things challenging. In any case don't fly downwind of the pilot position too much; you may not get back. When you are done with this thermal or lose it, remember to use "speed" flaps to head back upwind to the hunting area again.

If I figure out how I'll try to post an AFPD video soon.

Good luck and happy hunting!
Clark
(FallingWithStyle)

An excellent post! This is exactly what I want to do with AFPD (when my Commander version arrives).

What you describe sounds very much like real thermal hunting.

Overall, is it a realistic simulation of thermal soaring?

- Eric

Thanks Eric!

It seems to be very realistic to me. Especially the subtle thermal signs. Their ex*****ve "perfect" models have less drag than my cheaper birds but that's understandable.

Clark

Thanks Clark! Appreciate the help. I have to get some thermal practise in so I can hopefully actually catch one this weekend with the electra I'll go try your settings and tips. I did have a big problem spotting the changes in attitude of the glider when hunting but maybe I just need to set up viewports well enough etc. Will keep you posted on my findings. I also didn't fiddle with CG setting too much but yes that could make all the difference for sure with the glider's reaction to the thermal. I just couldn't find yet if the simulator actually shows the change of CG difference like it would in real life. I still need to move my Electra's CG back as well to get it closer to the stall...haven't had enough flights on it to get it tweaked yet.

Oh, here's another tip: the more stable you fly (or the plane flies) the easier it is to see disturbances (like thermals) in the air.

You should trim the plane so it flies straight and on its shallowest stable glideslope completely "hands off", with the stick at neutral. Even better, you should be able to put the plane into a shallow bank and hold it there with very little back pressure on the stick. Turns should be perfectly coordinated; aileron differential can reduce or eliminate the need for rudder. After your cg is set, adjust elevator trim and aileron differential so you can fly the plane almost effortlessly.

This can be really thrilling if you get the trim right. My aircraft (in AFPD and real life) are trimmed out so well it feels like all I'm doing is "suggesting" to the plane where to go and it flies there all by itself. Which is good because the plane flies itself better than I can.

Clark

Clark,

Thanks for the informative post. Which radio are you using ?

I use the USB cable to connect my JR 9303 (sailplane version). I highly recommend it if you intend on being in the rc aviation hobby for the long run. It will easily handle any airplane/heli you will ever buy (or fly in a sim ).

Clark

Ahh Clark I had some fun last night! I completely forgot that I can switch on the follow mode camera in the second view window. It was now much easier to see the thermals bump the plane around when you hit them. Thanks for the help. I have not been able to play with all the settings you provided yet because I can't get my 9X to work with the sim yet...still having problems finding another headphone plug. But I did take some of the other just normal gliders last night and thermalled my brains out. It sure was great fun when I was actually able to see what the plane was doing. No need for no stinking vario meter anymore!!! I did print out everything you wrote up untill now so as soon as I get the interface sorted I'm going to play with the sailplane programming in the 9X a bit. Today I am getting my new motor for my electra so this weekend is serious thermal hunting time again.

Glad to hear it Spacey. I didn't even think about using "follow cam" since I'm trying to simulate my real flying experience. You have a great idea though for those trying to learn how the plane twitches.

Latest changes to the guide:
* I added some comments on the wind settings
* I removed the F3/F4 hint for cg adjustment. Turns out the software forgets the F3 data once you leave the sim to enter the editor.
* CG HAS MOVED BACK TO -1.75 in.

The new cg improves pitch neutrality even more and reduces the amount of elevator trim needed to hold a glide slope so the plane should fly more efficiently. Stability didn't appear to suffer with the change.

So far, I've never been able to pick up a thermal below 100 feet. Either they are not modeled down that low or they are too weak at that level for a 3m plane. Someday I'll try a smaller HLG and see if I can find a thermal that low.

Clark

Finally got some stick time and recorded a 12 minute flight where I caught 3-4 thermals including one to 580ft over the span of 12 minutes. This was at thermal setting of "3" using the Ventus as modified above. The recording file is a whopping 39MB. Yikes! This is baffling because as far as I can tell all the playback gives you is the correct model and position over time. It zips to 11MB but this is still puzzling why it should be so big for so little information.

If someone can volunteer some web site space, I'll upload the zipped file.

Clark