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Jan 06, 2003, 09:32 PM
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How high to catch a thermal?


How high do you normally have to fly before you can start catching thermals? I'm a total newbie so promptly dismiss me if this is ridiculous. I swear that my plane seemed to fly more sluggish when it's closer to the ground & powered down as compared to when I go way up & power down to a similar throttle setting. Yesterday I was flying in very little surface wind but when I'd get up about 200' or so the plane took off & kept climbing. At one point I was having trouble seeing it & I was getting nervous sticking it down until I was comfortable with it. I was flying it "on a close reach" (excuse the newbie using sailing terminology ) -- sideways to the wind & trying to slightly turn up into the wind very gently almost like I was trying to beat a sailboat upwind. I tell you I had the plane down to around 1/4 throttle & I felt like I could fly around for an hour up there just going back & forth/in circles.

What ever I was doing it sure was fun!

Chris
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Jan 06, 2003, 10:02 PM
Ascended Master
Sparky Paul's Avatar
Thermals start at the ground.
At the 1960 King Orange Internats in Florida, my A-2 Nordic was almost to the ground after being released at 180 feet, when the wings wiggled, and up it went for a max.
You have to learn the signals of a thermal.
First, fly upwind about 45 degrees off the wind, and beat back and forth, always turning into the wind. A direct entry to a thermal is indicated by the nose lowering, or more easily seen, the tail coming up, as the plane adjusts itself to the rising air.
If one wing goes into the thermal, that wing will rise.. you turn toward that side to get into the thermal.
Thermals generally come in pulses, with a minute or three between them. That's why you go upwind. Flying downwind looking for one results in long walks.
Jan 06, 2003, 10:24 PM
B for Bruce
BMatthews's Avatar
Sound to me like you were in a thermal. If you'd powered right off the model probably would have kept on going up.

And from the sounds of it you found one of the rare "all field" thermals. Usually thermals are quite small near the ground and bell out as you are taken up higher in them. But occasionally you get a really big and gentle area thermal that just takes everyone on the field up at one time.

As for how low they can go like Sparky I've had and seen lots of free flight models catch thermals at 10 to 12 feet and spec out before the DT cut in. That sure is a hoot isn't it Sparky...

I'm sure the RC hand launch crowd has similar stories.

I've been away from the soaring crew here for some years but a when I did hit the contests there was one guy that would hand launch his 120 inch Windsong to about 20 feet or so when he thought he felt something. I watched him work the base of quite a few thermals up to about 100 feet before he cut out and dropped down to 15 or 20 for another go. So model size doesn't really matter either.

That's what I like about soaring. The never ending questoin about what the air holds in store for us from day to day. Flying a glider is probably the easiest way to learn to fly RC but truly soaring is one of the most difficult to master.
Jan 06, 2003, 11:21 PM
Ascended Master
Sparky Paul's Avatar
My brother tells of watching Joe Wurts hand-launch a Paragon.. 114"! and spec it out in the SF Valley!
Out here in the desert some of the thermals are hundreds of feet wide at a reasonable altitude. Almost impossible to fly out of.
Brings up another tip. To get out of a thermal, fly upwind. Then do a square pattern back if you want to land, or go upwind to find the next one.
And watch the plane all the way down. There's rabbit f*** thermals that can lift or at least keep the plane up if you can stay in it with tight circling when you're low. But keep the landing in mind, don't get too low to get back.
Jan 07, 2003, 12:29 AM
Registered User
Sparky
I have heard it said that Joe Wurts can find thermals in a closet.

Windysurfer
However we humans have to do it the hard way. Learn your airplane so you can recognise the story you are being told on every flight. A wing dips or the speed increases so very slightly--maybe the plane wants to turn on its own or the nose may pitch up slightly--all could be signs of lift in the area. These signs can be very subtle and easily missed. Unless you stumble upon the elusive brick lifter your best indicator is your plane.

One last comment--speed will not help find thermals. In light lift you may fly through lift without showing any indicator because your plane was too fast. One reason good thermal ships are not the fastest in the sky.
Jan 07, 2003, 12:55 AM
Chemically Corrected
Grapeape's Avatar
Old Buzzard's Soaring Book, a great read, and quite entertaining!
http://www.carstens-publications.com/hangar/a11560.html


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