correct thermal technique

[patv]

Hi All,
If my plane (Gentle Lady) is correctly balanced and trimmed correctly...and I'm circling into what appears to be a thermal...

-should I be able to circle with rudder alone..or should I be adding a bit of up elevator if its correctly trimmed?

I trying to determine if I've got the plane well trimmed or just "in the ballpark".
and find the best technique for thermalling.

Thanks
Pat

[Sparky Paul]

You will have to add a bit of elevator when circling.
Either trim it in, or hold it. I prefer to hold it.. if the plane shows it doesn't have enough, then I go try to recenter the thermal, the plane is losing the thermal.
Holding elevator gives a good feedback as to what's happening.

[patv]

Thanks Sparky Paul. I'll hold the elevator in when circling so trim remains correct while searching for lift

[nuevo]

You may have to add rudder (in or out of the turn), if you want to change your bank angle. For me, once I get my bank angle reasonable, elevator stick movement does 80% of the work for me. If the plane is well designed, it will pretty much maintain that bank angle in the turn without further rudder input.

[patv]

I'm probably using too much rudder and not enough elevator. When I begin to cirlce its fine but as I continue to cirlce my control is off and it could be too much rudder. I try it this weekend and see if it helps.

Pat

[loic_debisschop]

When circling you must keep the fuselage horizontal, nose slightly down. This is necessary to keep the same speed, which should be the lower sink rate speed ( approx. 20 % higher than stall speed)
Keeping fuselage horizontal will require most of the time up elevator,because the glider kas a natural tendency to pitch down when circling, but sometime you need DOWN elevator, because this natural tendancy is not a rule. Some example where you may have to put down elevator:
- Turbulence (happen often in thermals, it's a good sign !)
- When you reduce the bank angle (95 % of the time)
- When you applied to much up elevator, and you are to close from stall
So the only rule to remember is keeping fuselage close to horizontal. You can try circling even without lift in calm air, to feel what's happening when you increase or decrease bank angle. The more bank angle, the more up elevator, but this is not a rule, it's only the consequency of the rule above.

Loïc

[fprintf]

The biggest mistakes I always make, as a beginner-intermediate, are using too much rudder and not allowing the plane to fly at a good speed. I think you have already noticed, but too much rudder can cause the plane to turn onto a wingtip and without elevator it drops the nose. If you use too much rudder with an equal amount of elevator to stop the nose from dropping you end up with a stall as the plane slows down from the drag of the control surfaces. By not allowing the plane to fly itself (waggling the sticks too much) I find that I end up coaxing the plane into a stall as I try to fly too slowly.

My best flights (and I had a good 10 minute thermal flight this past weekend) are when I fly the plane into a thermal at a good height and make good wide and flat turns. My worst flights are when I use too much bank angle - for me it is better to make wide open turns and fly repeatedly through lift than it is to core the thermal with tight turns. Somehow I think I am more successful because the tight turns require better attention to airspeed, a lot of elevator and it places the plane closer to the edge of a stall, which usually robs me of any extra height gained by coring the thermal.

[schrederman]

If you can learn to circle tightly, you will be able to use the lift more effectively. Many people comment about how tightly I circle. I will do my best to find the core of the thermal, where the air is rising the fastest, and circle there. Yes, the bank angle is great, often 60 degrees. The stick is more often than not at the backstop, ie I hold full up elevator. More often than not, the conversation turns from how tight my circle is to how I got above them. In wide, slow thermals, the lazy, wide circle is OK. Where the thermals are quarter to dime size, you need to know how to thermal tightly and effectively. Remember that thermals are small close to the ground. If you are going to save your flight from 20 feet, you need to be able to circle tightly with confidence. Correct dihedral is essential in this flight regime. Too little dihedral with an RES sailplane is really difficult to handle. Heavy wingtip panels are another problem area. Practice these techniques when up high and get confident before trying down at save level.

Hope that helps... It's the same for flying real gliders, too. I do lots of 2g turning...

Jack Womack

[nuevo]

Jack's got some good comments here. I agree.

To broaden the topic just a little bit...

When you get a little more advanced, watch your plane closely during the circle. If the plane is climbing better on say the left side of the circle, widen your circle on that size and move towards the stronger lift. You know you've got the thermal 'cored' when the plane is climbing equally all the way around the circle.

Oh, just because you have it cored now, you may not be in 30 seconds. Thermals can change shape/size/position as you climb out.

[fprintf]

Awesome helpful comments Jon and Jack. Thank you a bunch! As for the thermals changing shape/size/position that is absolutely one of the bigger challenges. For two or three turns the plane is going up and then *pop* it is coming down even though the turns are moving with the wind. In my mind I picture thermals like tornadoes on the Wizard of Oz - moving all around the sky sucking things up, but moving all the time.

Another challenge alluded to earlier is telling when the plane is going up or not. Unless you have some perspective, like the plane against the tree line, it is difficult to tell if the plane is getting smaller or larger. I think this may be why it is said that beginners too often circle in bad lift... we just can't tell within one circle what the plane is doing. Now that I am more experienced with my one plane it has become easier, but I still do the multi-circle thing more often than I'd like.

[WimH]

If you can learn to circle tightly, you will be able to use the lift more effectively....
Jack Womack

I just realized this in the last couple of weeks. I'm no thermal flying expert, but finding and exploiting low-level thermals is what I like to do most of all. I had noticed recently that when circling tightly, it seemed as if there were much more thermals about than I ever could have imagined...Before that, i could only find them on certain days. Now I realize there's always some thermal activity around somewhere.(when I just started glider flying I thought thermals were a hoax...)

[WimH]

... but I still do the multi-circle thing more often than I'd like.

You're not alone...

[Hostage-46]

Jack's got some good comments here. I agree.

To broaden the topic just a little bit...

When you get a little more advanced, watch your plane closely during the circle. If the plane is climbing better on say the left side of the circle, widen your circle on that size and move towards the stronger lift. You know you've got the thermal 'cored' when the plane is climbing equally all the way around the circle.

Oh, just because you have it cored now, you may not be in 30 seconds. Thermals can change shape/size/position as you climb out.

A trick I picked up from a pro was really simple. His comment was the most folks turn too soon when they hit lift, particularly when getting a little edgy runnning down wind, thus sometimes ending up in the edge and not coring.

His point was, when you hit the lift (this does not apply to low altitude per say) maintain heading, and in fact, you might even fly to the other side to better define the thermal. This gives you a better feel for space you're working with. The other thing is, don't assume the lift is in a uniform shape. If I had thermal glasses I bet the flying field would look more like a lava lamp. Lot's of non standard blobs of warm air going up, cooling and coming down. It would be real interesting with a bit of a breeze and local obstacles.

I was also taught this in my full scale soaring training. However I'm sure Jack will agree it's easier to define the thermal core when you get an 8KT kick in the seat!

[fprintf]

A trick I picked up from a pro was really simple. His comment was the most folks turn too soon when they hit lift, particularly when getting a little edgy runnning down wind, thus sometimes ending up in the edge and not coring.

For those newbies that question their desire/need to go to contests, I picked up this exact tip from an expert F3b flier at my second contest and it has improved my ability to find and stay with thermals significantly. I was doing the 'wing tip goes up, turn immediately toward the upturn'. Now I wait and see what will happen - if there is a thermal there it will likely not disappear in the second or two I fly past the bump. It is awesome having experienced fliers talk into your ear while you fly... it is even better once you are past the porpoising/plane control stages and can actually fly smoothly according to the directions given. :)

[Hostage-46]

It is awesome having experienced fliers talk into your ear while you fly... it is even better once you are past the porpoising/plane control stages and can actually fly smoothly according to the directions given. :)

The importance of flying with others can't be over emphasized. Show up, watch and listen. Find a mentor or two if you can.

'cause if you ain't cheatin', you ain't tryin' ;)

[schrederman]

I've been accused of using the hair on my legs to detect thermals.... I must dispell that notion immediately. All of the information here is really good stuff. The core does move around. Moving the circle with the core is something I do when I can. The porpoising model thing is something we all do at times. If you don't, you are flying too conservatively. Some think that minimum sinking speed is somewhere quite a bit above stall. Even if it is, the slowest speed possible will keep your model or real glider in the center of the lift better. The center is going up the fastest... watch the hawks if you don't believe me... and will more than make up for the difference in a slightly higher sinking speed.

In one of my training flights, I thought I was kicking @$$ in a 5 knot thermal. My mentor, who was showing me how to go faster on X-C flights, took the controls and pegged the variometer at 10 knots. The glider with 2 passengers weighed about 1300 lbs. We were in a 60 degree bank, with the yaw string off center just a touch, at the top of the yellow arc on the ASI, and the stick on the backstop. We were VERY close to stalling, and in fact had the ship shuddering from time to time.

Good Friday was the first time in a long time I've had an 8 knot kick in the pants. It was emphasized by a pull up from 100 knots. When the vario started showing up air, I eased the stick back and went screaming up, trading that speed for altitude. When I had slowed to 45 knots, I dropped the flaps and ailerons to 8 degrees and began my turn with a roll in to 60 degrees. It took about 3 turns to get me centered in the thermal, and with practice, I'll be able to do it quicker.

One thing I'd suggest to any R/C sailplaner, is to go and buy 1 hour with a good glider pilot in a 2-place sailplane. You'll get a much better perspective about thermals. You'll come away almost not believing that the air you can barely feel moving against your face can really lift you and the sailplane at 1000 feet per minute, and more at times...

Enjoy

Jack Womack
PIK-20B N77MA (AZ)

[Keith Johnson]

Great post Jack. It is one thing to stand on the ground and look at our sailplane lift in thermals and another to be inside a sailplane and experience thermal flight in person. Nice to read the experience posted here.

[schrederman]

Well, after getting to fly my old Windfree a few times, I went to fly my big ship. I was at the north end of the field when I noticed an RV-4 (nice homebuilt airlane) taxiing off the main runway at Soaring Club of Houston International. It was our friend Richard King. He is big into scale sailplanes. He came down to the staging area and we had a nice chat. He ran my wing as I took off. A little while later, he circled me several times at about 5000 feet. As I took off toward another thermal at about 90 knots, he passed by me on the left at about 150 knots and did a nice good-bye roll on his way out of the area. It was good to see him. It was really fun to see him in the air.

The day was pretty good. My max altitude was cloudbase, which was about 5900 MSL. There was 6 to 7 knots lift at times, but I averaged about 4 knots up. I spent a lot of time in 2g turns, but a lot of time running in good air, with many runs at 80 to 100 knots while maintaining altitude. I ran 24 miles between 2 towns and never circled, and lost only 300 feet in the process. This was one for the books for me. I'm glad it was because our trip and surgery on my arm will keep me from flying anything for a couple of
months, at least. I'll probably build a toy or two while my rebuilt arm grows back on... hehe... Grand Esprits and Legionairs and Houston Hawks... OH MY!!

I'll see you all on the flip side.......

Jack Womack

[nuevo]

It is one thing to stand on the ground and look at our sailplane lift in thermals and another to be inside a sailplane and experience thermal flight in person.

The other side of the coin reminds me of a personal experience. I was at the local sailplane airport several years ago. My father-in-law was receiving his first glider ride as a birthday present. I talked to one of the ground crew after they took off.

When I told him I flew thermal RC gliders, he stopped and his jaw dropped. Then he asked "How do you know you're in lift, if you don't feel the thermal kick you in the backside?" :D :D


Jack, thanks for the insights and stories. Captivating!

[ferincr]

Long time ago I was in this little town for a triathlon competition in argentina and I met a instructor pilot (or pilot instructor?) he gave me a ride in a super Dimona, and when I told him I did a bit of r/c he gave me the controls, what a rush! I think it was easier to fly than the r/c's (at least until I was getting close to land) I still remember the feel of the lift (I think the biggest one we hit was like 7 knots).
Fernando

[bigjohn]

Visualizing lift: There are two thermal effects that I can think of, that are visible and at different ends of the thermal spectrum. One would be smoke from a campfire. That smoke is basically going to define the shape of a thermal. So, you can watch how it surges, and jets upwards, and then sometimes levels and goes sideways. I am reminded of a time over a decade ago when I was on a road trip and there was some sort of structure or junk fire burning off the side of the interstate. There was no wind, and I followed the smoke column up, up and up to a few thousand feet, where a FS sailplane was happily circling.

The other example I can think of is the southwestern dust-devil. I've seen dust devils here in Florida, but out on the desert around Phoenix, you can see a line of dirt in the vortex that can extend 1000 feet into the sky. Often this dirt filament will be surrounded by papers & junk that have been picked up.

FWIW, anyway...

[Peytr]

Training your circling technique is best done at lower altitudes and a bit away so you can view the plane from the side. I Found I could work very light thermals at 30-50 m, just because I could see better what I'm doing.

Correct bank/pull/rudder is a highly intuitive skill (combined with knowing your plane, any airframe behaves different). Although risks of low altitude circling are obviously higher than doing them at 100+m, you get a good feel once you regularly do it. This convinced me of the fact that small planes (like HLGs or 2 m at the most) can teach you a better thermal technique than larger ones. Do 100 bungee launches at 200 ft with you small plane (with or without thermals) and you had better training than 50 at high altitude. Once you master the skill you will discover thermal activity is everywhere on most days.

Another important thing is that you can't master all skills in one go. When starting to learn flying thermals you have to get the hang of circling first and just after that try detecting and coring thermals. Trying to do both at the same time takes longer and doesn't get you the flying skills to get the most from it.

Then finally a point which might be subject of some controversy:

I found that a bit rearward CG gives me better circling. Of course the plane is a bit more twitchy, but has less tendency toward porpoising. Though planes fly with a wide variety of CGs, I feel the optimal CG for good thermal behaviour (and tight circling) to be is in a much narrower slot.

[Ollie]

http://www.nesail.com/articles.php

Learning To "See"

by Mike Lee

While there is no doubt that a large number of people must wear glasses for perfect vision, there is a little-known fact that people only see what they want to see. Most of the time, we see only those things which are in close proximity to us and ignore the rest. But when we fly aircraft we must be able to see or we are lost. There is a way to help yourself.

Good eyesight doesn't require you to borrow the eyes of an eagle to be great. Even if you wear glasses, the trick to seeing well is to train yourself to do so. This is really easy to do, and you can do this anytime that you are awake and looking around.

The first thing to do is try to notice everything around you. Look especially for details of items like the leaves in the trees, not just the trees. Look for the name emblem on a car as well as the entire car. Watch for the things within your peripheral vision without moving your eyeball from the spot it is focused on. After awhile you will find that you are seeing things you didn't see before.

Next, move on to more distant objects. Don't just look at a mountain in the distance, look at the detail of the mountain in the distance. When you are out driving, look ahead, way ahead, for the street signs and read them. You will soon find that you are teaching yourself to see better. Your eyesight was always there for you -- it just wasn't fine tuned to see everything.

If you practice seeing with your eyes, you will soon find that your ability to identify the altitude of your aircraft at distance is easier than before. You won't worry about whether that last control input should have been left, or was it right? Consequently, you will recognize lift faster and run from sink sooner. It is a very conscious effort to train your eyes to see, but the results will last you the rest of your life.

http://www.djaerotech.com/dj_askjd/dj_questions/thermturn.html
http://www.djaerotech.com/dj_askjd/dj_questions/smoothturn.html
http://www.djaerotech.com/dj_askjd/dj_questions/thermal_snif.html
http://www.djaerotech.com/dj_askjd/dj_questions/thermals.html
http://www.djaerotech.com/dj_askjd/dj_questions/vario.html

[patv]

Thanks everyone for all the great info. I'm working on flying smooth and circling technique.
I know the lift is there...I just need to improve my skills with practice.

Pat

[Yardbird]

Use care Pat.

I lost my GL in a woody swamp last week. Trying to figure out what happened. I was seduced by my first real boomer, and probably got too far downwind. Either I hit sink on the way out, or the ol' floater just couldn't penetrate back upwind. Anyway before I knew it, I was low over the trees and lost orientation. Stalled and went in. :(

Being a newbie, I didn't have the knowledge to mark the bearing with the transmitter antenna and wandered around the swamp, finally quitting when I lost a shoe.

For me some valuable lessons learned. My replacement GL ARF is almost ready and it WILL have a lost model alarm and a wiser person on the sticks.

Keep up the good work.

Tony

P.S. Ollie, where do you come up with those great links all the time? :)

[ferincr]

My replacement GL ARF is almost ready and it WILL have a lost model alarm

Hi Yardbird,
what do you mean by that?
Can you buy those?
It's one of my concerns (losing a plane) I know that when you start it's near to impposible to catch lift, but I live in the tropics and see the birds flying all day long without flapping the wings once so everytime I read about somebody losing a model either due to fly long distance downwind or not being able to get it off the lift gives me the itches.
Thanks,
Fernando

[Yardbird]

Here you go Fernando, I've also seen them on eBay as well.


http://www.californiasailplanes.com/accessories/Lost%20model%20alarm%20New.htm

http://www.skykingrcproducts.com/accessories/lostmodel/lost_rc_model_alarm.html

Tony

Fernando, I've got both on order for evaluation. I'll let you know what I find out. Tony

[ferincr]

Thanks,
One thing I'm not very clear on.
Do these alarms make the lost sound through the whole flight? or they "activate" the sound when you lose your plane and turn the Tx off but the Rx still on?
Fernando.

[Sparky Paul]

When you're "seduced" downwind in a boomer.. remember the glide angle your plane has.. and keep at least high enough to come back from wherever..
Especially with the floaters.. these don't come upwind well... :(

[Ollie]

"Ollie, where do you come up with those great links all the time? "

I started as a modeler in 1937. I love knowledge even now. I am still a student of skilled and knowledgable modelers to this day. My hero list is at Dr. Mark Drela, Don Stackhouse, Joe Wurts, Dave Thornburg and many, many others.

[Yardbird]

Thanks,
One thing I'm not very clear on.
Do these alarms make the lost sound through the whole flight? or they "activate" the sound when you lose your plane and turn the Tx off but the Rx still on?
Fernando.

Fernando,

They have several functions. If the Rx is on, and the Tx off, you get the "Lost Plane" alarm. Otherwise they are silent unless your Rx battery starts getting low or your are getting some "glitches", (depending on the model). If you are talented, you can construct your own. Several sites have plans (schematics) and instructions.

[ferincr]

Yes, that makes sense. After I thought about it I kind of realized that was the way it should work, but that's my problem my tong (fingers in this case) is faster than my brain.
I saw some schematics in a web page called electronics projects for r/c.
I don't know if you know another one, I'm always interested to see new gadgets I can build at home (and most of the time I don't succeed to make them work).
Fernando

[Yardbird]

Here's one: http://thelocust.org/soaring/lma/

Another: http://www.designsoft.com.au/ahome/rc/PIC-LMA/LMA.html

Try a Google search on "lost model alarm" That seems to get a good number of hits.

Tony

[ferincr]

thanks.

[Don Stackhouse]

You may have to add rudder (in or out of the turn), if you want to change your bank angle. For me, once I get my bank angle reasonable, elevator stick movement does 80% of the work for me. If the plane is well designed, it will pretty much maintain that bank angle in the turn without further rudder input.

There's a lot of weird things that interact during a thermal turn, some of them seemingly contradictory.

On small models (like HLG's) in particular, where getting too slow can get you into performance losses from having the Reynolds numbers too low, you should be careful to keep your speed up. On the Chrysalis, our basic advice is to try to keep the fuselage parallel to the ground.

That said, you will probably have to hold at least a little bit of "up" in order to keep the fuselage at the desired attitude. This effect is proportional to the radius of the turn in comparison to the length of the fuselage.

The culprit is curvature of the airflow due to the turn. If the plane is flying in a curved flight path, then to the plane, the airflow past it feels curved. In really tight thermal turns, this can make the relative wind at the tail more than ten degrees different from the relative wind at the wing, in both the pitch and yaw directions! The effect of this curvature is to try to yaw the plane to the outside of the turn, and to push the nose down. You may have to hold rudder into the turn, and probably will need a pretty large dose of up elevator.

For example, on our old "Monarch" RCHLG sailplanes, a max effort thermal turn might require twice as much up elevator just to compensate for this curved airflow than it takes to stall the model in level flight! Of course if you hit anything (gust, etc.) that suddenly alters the radius of the turn, you have to instantly back off on the up elevator or the model will stall. It's a lot like playing a fish on the end of a fishing line.

[ScottN3N]

Another thing to watch is the speed. The best thing to do is keep your hands off the controls as much as possible so you can observe. If you are constantly moving the sticks, you don't know if it's the air or your fingers that is causing a movement. Fly smoothly. The wing tip from a thermal is more obvious, but a thermal will also affect the speed. If you fly strait into the thermal, the wing may not rock too much, but the speed should increase slightly. The upward moving air will tend to push the tail up and the speed will increase. If you find yourself having to add a but of up trim after the glider has been trimmed, then you are likely in lift. Conversly, if you're in sink, the opposite will happen. These are small changes, so you have to really be concentrating on everything the plane is doing, not just looking for one wing or the other to lift up.

[jcats]

These are some good tips!!! Thanks guys!
I fly an electric Stork 2 Pro and it wants to pitch down during a turn. They say that I may have too much (too little aileron down deflection) aileron differential. what do you guys think?

Also, Do you have up elevator/down flap mixed in? I do and I have mixed feelings about it-- Or maybe I just dont know when to use it or not.

thanks,
jc

[Don Stackhouse]

These are some good tips!!! Thanks guys!
I fly an electric Stork 2 Pro and it wants to pitch down during a turn. They say that I may have too much (too little aileron down deflection) aileron differential. what do you guys think?

Might have the C/G too far forward. I doubt that aileron differential is doing it. Once the bank angle is established, you only use tiny amounts of aileron to keep the bank angle where you want it, so there shouldn't be enough aileron deflection during the turn to be a significant factor.

In a turn, you're using some of the plane's lift to pull it around the turn, leaving less to hold it up against the pull of gravity. Since the model still weighs the same, gravity is still the same, so you now need more total lift to handle these two simultaneous jobs, in comparison to what you needed in level flight. The model will naturally start to descend. If the model has the C/G far enough forward to give it lots of static pitch stability, it will react by dropping its nose and gaining speed to make the extra lift.

When you level off after the turn with a model with this setup, it will now be going too fast, and will tend to pull up into a climb.

Of course the other option is to hold just enough up elevator to hold the pitch attitude constant in the turn, then smoothly release it as you roll back out of the turn. However, there is only so much of that you can do without causing a stall (see below).

If the pitch stability is weak (i.e.: aft C/G), it will tend to hold the same pitch attitude, which (in combination with the downward change in the flight path) results in a greater angle of attack for the wing, and that creates a higher lift coefficient to make the extra lift required, without a big change in airspeed.

Unfortunately, there is only just so much lift coefficient your wing's airfoils can make before they stall, so too steep a turn plus not enough airspeed = bad. In a 60 degree bank, the plane feels 2 G's, so the stall speed will be 1.41 times greater than in level flight. In other words, if the model stalls at 10 mph in level flight, it will stall at 14 mph in a 60 degree banked turn.

Then, on really lightly loaded models that can make very tight turns, such as some RCHLG's, there's the effects of curvature of the airflow in a turn. If the flight path of the airplane is following that of a banked turn, then the airflow past the model is curved. This means that if the airflow past the wing is straight, then the airflow at the tail (the "local relative wind") will be blowing inwards and upwards, which tends to yaw the plane to the outside of the turn, and push the tail up (and therefore the nose down). You will need some up elevator and some rudder into the turn ("bottom" rudder) to counteract these yawing and pitching effects.

Meanwhile you might have to add some aileron to the outside of the turn ("top" aileron) to counteract the fact that the inside wingtip sees a lower airspeed than the outside wingtip.

In a really tight thermal turn, it's not unusual for the local relative wind to be more than ten degrees different from the airflow direction at the wing, in both the pitch and yaw directions! On some of our HLG designs it was common to need more than twice as much up elevator in a tight thermal turn to compensate for this curved airflow than it took to stall the model in level flight! Of course this means that if you hit a gust, or something else disturbed the turn (widening the turn's radius, and therefore reducing the curvature of the airflow), you have to be ready to immediately back off on the extra "up' elevator or the model will stall! Working really tight turns like that ends up being a lot like playing a fish on the end of a line.

Also, Do you have up elevator/down flap mixed in? I do and I have mixed feelings about it-- Or maybe I just dont know when to use it or not.

thanks,
jc

You use it if (and only if) your model needs it. Ideally, as you extend flaps, the pitch attitude should stay about the same, or maybe drop the nose just a little. Some models will tend to raise the nose and others will tend to drop the nose when you extend flaps. You start testing with no compensation, then add whatever compensation you need to make the model fly the way you want it to.

[RTHawk]

I have read that it is better to turn into the rotaion of the thermal for slower speed. Can thermals form a rotation in either direction, or just one direction like water going down a sink drain. One direction north of the equator, the other direction south of equator. At what altitude AGL is the best for finding the stronger thermals.

[Hostage-46]

As you go higher, they expand. If you can core it and then setup a nice stable turn, the rest is gravy, no matter what direction you're turning.

Thermals do not have uniform rotation or shape, picture a lava lamp :) Odd shapes triggered by different conditions. As they ascend they merge, and where this is lift, there will also be sink.

I'm suprised at how many RC and full scale pilots favor one direction of turn, you see it in the landing pattern as well. Turn in the direction needed to core the thermal. Also, if one plays by full scale rules, if you join a thermal, you should turn in same direction as the airplane you're sharing the airspace with.

How high? I hooked one at about 10 feet on Monday and worked it to 800 feet while drifting down wind at 7 mph, then ran back up wind and found another, I had a few 15 min flights that day, which was better then some who were flying off the winch!

On a good day here in Texas, you can stay up as long as you like from 800 - 1000 ft. Full scale guys can go up to 10K in peak season.

[RTHawk]

Dan
Thanks for the tips. Iam located north of you at Lake Texoma and the thermals have really been good here as well. Finding and flying thermals is rather new to me, I learn something new each time I fly. We have a lot of Black Buzzards around here and they seem to have the technique down pretty good. I will follow them when they are around and can usually pick up the thermal they are in. I have had some really long flights, low batteries will some times terminate the flight before loss of lift.

[Hostage-46]

Cool,

Come on down and join us, we have several OK pilots at most contests. www.slnt.org

[RTHawk]

Will try to make one of your events. Always something too learn from watching experinced pilots.

[ChuckA]

When in a thermal, turn in the direction your model flies the best. This used to be more important in the days of built up wings but I notice that even my modern ships temd to fly smoother when circling in one direction than in the other. Could be that I could get both circles to fly equally well with a little more work but I don't bother unless circling in one direction is much better than the other.