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- Newsgroups: rec.models.rc
- Path: sparky!uunet!ftpbox!mothost!white!rtsg.mot.com!svoboda
- From: svoboda@rtsg.mot.com (David Svoboda)
- Subject: Re: More R/C Gliding........
- Message-ID: <1992Jul22.233354.6431@rtsg.mot.com>
- Sender: news@rtsg.mot.com
- Nntp-Posting-Host: guppie44
- Organization: Motorola Inc., Cellular Infrastructure Group
- References: <1992Jul18.214223.1@cc.curtin.edu.au>
- Date: Wed, 22 Jul 1992 23:33:54 GMT
- Lines: 70
-
- Prolific today, ain't I? :-)
-
- In article <1992Jul18.214223.1@cc.curtin.edu.au> tmarshall01@cc.curtin.edu.au writes:
-
- |Q:
- |THERMALLING!! How does one find a thermal in an R/C plane!!
- |I know over trees you can get a bit of up draft...
-
- Tips on thermalling--
-
- 1. Look for thermalling birds. This is a good hint of rising air. Don't
- piss them off.
-
- 2. Small, fluffy cumulous clouds indicate better thermalling weather.
-
- 3. When flying, watch the airplane closely. Fly smoothly. If you see
- the airplane bank over of it's own volition (and you didn't get a radio
- glitch), that usually means that you have a thermal on the side that the
- glider banked away from.
-
- 4. If the airplane "wiggles" about the yaw axis, you have crossed a vertical
- air transition, and may be in a thermal.
-
- 5. Think of a thermal as a "bubble" of lift, rising from the ground. Sometimes
- you can circle in it, like a bird (if you can place it that well; this is difficult).
- Also, the airplane sinks more when you turn. Sometimes you just work back and
- forth across the region, always turning into the wind. The thermal moves
- downwind, a little slower than the wind speed.
-
- 6. You don't climb with elevator. Let the thermal do the work.
-
- 7. Don't insist on a strong rise. If you are simply sinking more slowly, you are
- gaining something.
-
- 8. A thermal is stronger, the higher you find it. Some thermals extend up many
- thousands of feet. This can be dangerous to your airplane. On the other hand,
- when you get low, land; you probably won't find a thermal down here.
-
- 9. Find a "cruise speed" and a "thermal speed" for your particular airplane, and
- memorize the elevator trim positions for these. Cruise speed is usually your
- best glide ratio; that is, it's when you cover the most ground horizontally, for
- the amount of altitude you are losing. This is typically pretty fast. Thermal
- speed is your minimum sink rate, usually just a bit faster than stall.
-
- 10. Use the cruise speed for searching, and when you find a thermal, bring it back
- to thermal speed to stay with it. Flaps and computer radios are good for this,
- but the elevator trim works, too.
-
- 11. There are also "downers", usually following thermals. These are like "inverse"
- thermals, which pull your airplane down. If you find yourself descending faster
- than you expect, don't pull up elevator, push down elevator, accelerate and get
- out of there.
-
- 12. Some sailplanes exhibit pitch changes with different rising air rates. My
- Sagitta 900 would consistently pitch down in the presence of a thermal, proportional
- with the strength, so I could just hold the fuselage attitude constant and pay
- attention to the elevator I was holding to do so, to guage the thermal strength.
- Real boomers would require full up elevator!
-
- 13. Take a pair of binoculars along. It really sucks to have to come down just
- because the plane is getting too small.
-
- 14. You can feel a thermal pass you. The breeze stops, it's warm and calm for a few
- moments, then you feel a cool breeze. A thermal just walked over you. The top
- extends downwind from where you are standing.
-
- 15. If you get the thermal flight of your life, pay attention to how much time you
- have on your receiver batteries. (Ask me how I know this one. :-( )
-
- Dave Svoboda, Palatine, IL
-