Tips on recognizing thermals

[fprintf]

I saw a response in the longest flight thread about not being able to hook onto any thermals. I have a few guys instructing me at the local field soon and they have already been telling me what to look for. How about a thread on recognizing thermal activity, and then what to do about it?

So far I have heard:

If the wing tip rises, turn immediately in that direction and you may find a thermal.

If the plane speeds up and the tail raises (without any operator input) then you have flown straight through a thermal. Make a 180 to find the thermal.

When trying to "core" the thermal make tighter turns (45 - 60 degree bank angle) at medium altitude. Make shallower turns higher up. When at lower altitude just look for a good place to land since tight slow turns may lead to stalling.

I suppose this is all predicated on good flying skills, that is, the plane is already flying smoothly not porpoising around due to operator overcorrection.

Any other tips for beginners?

[rcav8r2]

I have thermaled quite a few times for over an hour....

...I must admit they were 'acciental' I tried the tips you mentioned without great success. I have no problems flying a plane smoothly, and ususlly just fly my glider with the trims, and can land it at my feet almost everytime.

There is a guy at the field that knows when to launch. When I followed his advice, I got the long flights. One over an hour flight was with a Zagi, 1700MAH battery, and about a 30-40 second motor run. I brought it down fearing I would run out of battery., and after about an hour, the activity strated to die down. This day was the classic big puffy clouds with the slightlty black bottoms. I asked how he knew when to launch as when I was getting ready to, he said to hold off for about an hour. He siad something about the clouds being at the end of their cycle, and to wait till new ones build. Well sure enough about an hour later, he said it was time to launch, and told me where to fly. It was just upwind of a just developing cloud. Within about 30-40 seconds after launch, it was going up faster and faster, and this was after I shut the motor off.
From then on, I just baild out when it got too high to see, and moved to the next developing one.

The others were ones I just stumbled up on :-)

I was thinking about getting a Dave Throburg (sp?) book/video, as I have heard great things about them.

Good question.. Can't wait to see what the "experts" have to say :D

[Ollie]

Besides how your plane reacts to thermals, there are many cues to where thermals are and where to look for them.

There are the visual cues:
1. Circling birds
2. Debris such as dust, dandilion seeds, bits of trash etc. swirling around and rising.
3. Insect eating birds darting after insects that have been lifted by rising air.

There are wind cues:
1.When the wind stops blowing or gets weaker and the air gets warmer, the thermal is just up wind or overhead.
2. When the wind shifts, it is often the surface air feeding the thermal, and the flow is to the thermal.
3. When the wind picks up, the thermal is downwind.

There are natural thermal generating spots:
1. A black top parking lot, plowed field, etc allow the surface air to heat faster than the surroundings and therefore produce thermals.
2. The lee side of buildings, tree lines and other obstructions slow the flow of surface air and give it a chance to heat longer to produce thermals.
3. Buildings with furnaces or air conditioning are heat sources that produce thermals.

Sometimes nonthermal lift is generated by colliding air masses. A mass of cold air sliding under a mass of warm air not only produces spectacular lift but often stormy conditions. Here in SW Florida during the summer, when there is an easterly breeze in the morning and a developing westerly sea breeze later in the day, the gently colliding air masses may not be acompanied by rain yet produce a wide area of lift that persists for as much as an hour.

[John Gallagher]

On some gliders the nose will bob up when you enter lift.
A glider flying in stable air will lose altitude. So you want to watch for when the glider is either gaining altitude or not losing altitude. If the glider isn't losing altitude, it's in lift.
Beginners have the most difficulty in centering the lift. When you make a circle you have to watch for which part of the circle that the glider is gaining altitude and adjust the circle to center on that spot, remembering that most thermals will be drifting with the wind.

[BatteryJockey]

My 2 best flights were accidents, one with a Bird of Time and once with a Dodgson design V Gilante. on both occations I was coming down and at about 100' I landed on top of a rising thermal. on both occations the thermal almost took the plane out of sight. The one thing that I have always had luck with is flying under grey clouds. They have always maintained hieght or gotten pulled up towards the cloud until I bail out from under it.

Gilbert

[Randy G]

I was flying today at 60 acres and had a great day of thermal hunting. The first plane (Taboo dlg) I was launching and flying for about 30 minutes with just small thermals and then saw another guy with a 4meter take off at the edge so I followed him. I ended up having the T being extremely high and for so long I was afraid the battery was going to die so I landed.

Then, for an encore, I brought out the Boar 2meter from Arthobby.com and hi-started that. First few flights were not too spectacular then I hit a thermal in the opposite side of field and specked it out in about 5 minutes to fly 45+ minutes. It is easy at this field to hit thermals because of the surroundings: blacktop path, blackberry bushes, and on the end a ridge going up with houses. When I first started flying the T and Boar I usually circle the area looking for different areas of lift. Sometimes I will find lift in an area for a little bit then find another in a different part. There is a couple that always seem to produce lift but then other areas (depending on the conditions) will produce too.

Oh ya, practice too! Fly in a bunch of different conditions (cloudy, sunny) and at different times of the day too.

And the best part of having a day like I did today is coming home to the wife with a silly grin on your face! :D

[denete]

As far as flying in distant air and spotting lift, here's a tip I learned a year or so ago. Follow the tail. If your tail goes left, hunt to the left of the plane. If the tail goes right, hunt to the right. If the tail goes up, pull back on the stick and climb in the lift. If the tail goes down, push forward and speed through the sink.

I really wonder about the whole "black-top, building, parking lot, tree line, etc." notion. I'm not a professional who can give you the how and why, but I really don't see these things as being able to generate lift in a fluid medium (like our atmosphere). Perhaps they contribute to the lift tendancies when "somewhat bouyant" air passes their way. They can kick off a thermal by perhaps heating the ground air. If you fly in bouyant air and pass one of these warm patches, you might find yourself in a full-fleged updraft as you move downwind.

Food for thought.

- David

[Soar_dude]

I found was I learning to thermal by myself was to do figure eights in and out of the thermal that way yuo could keep in the lift without worrying about staying in a tight circle "RES guys"
This is not as efficent as coring it but it is easier then trying to stay in a constant turn and losing it to a stall! I have gotten better at watching what the glider does and responding to it then trying to keep the glider rock steady straight.

Saor Dude

[Ollie]

Efficient thermalling is very much about finding where the lift is best and putting the plane there even when the thermal is trying to push the plane out.

The flying skills that make for better thermal flying are the concentration to know where you want the plane to go and putting it there with predision. The best thermal pilots fly with forethought and precision. That's why learning to land precisely also improves thermalling skill.

[BrianSmith]

As an "old" sailplane flyer, I would suggest you read and "re" read Ollies advise..My 2 cents...Brian Smith

[SESH1975]

Save yourself the trouble and just go sloping!!!

Shawn:D

[BrianSmith]

Hey, that is lots of fun too..I did it once for 8 hrs without landing...Brian Smith

[rcav8r2]

Originally posted by BrianSmith
Hey, that is lots of fun too..I did it once for 8 hrs without landing...Brian Smith

8 Hours !!! What kind of battery did you use?

Man I wish there was a place to "slope" here. :D

[BrianSmith]

In the model I used a pair 700 mah airborne nicads, I had two transmitters on the same frequency with 1100's in each one of them..It was for the LSF 8 hr level 5 flight..Was not nearly as tough as it sounds...Brian

[fprintf]

No reliable place to slope here in Connecticut either - both places I had in mind have resulted in other people's lost planes (one fell down a cliff when the wind died and ended up very high in the trees below, the other got caught in a wind gust and disappeared into the trees and has not been seen since). So go ahead and rub it in.

This is why I posted a thread on thermaling because that is all I can do (until I go to Cape Cod). Would you say it takes more skill to thermal than to slope (not combat)?

[Ollie]

Thermalling isn't hard when the lift is strong. Even a plastic garbage bag can be sucked up in strong lift.

Slope flying isn't hard if the slope site is free of obstructions and the rotor behind the slope isn't too strong.

When conditions are marginal and the landing area is restricted, then flying of either type is more difficult.

Pilots who can utilize the full speed range of their model and manage its kinetic and potential energy can fly in a wider variety of sites and conditions.

Pilots who allow their plane to float around aimlessly and don't fly with forethought can get themselves into difficulties even in favorable conditions at favorable sites.