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Old Sep 18, 2012, 09:19 PM
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Great stuff, CloudyIFR and Piper! I might have some questions for you guys once I plow through it. In the meantime I hope that this thread will become a place where beginners can ask us all questions more or less in real time.
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Old Sep 19, 2012, 01:42 PM
B for Bruce
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The 'Wack, BC, Canada
Joined Oct 2002
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Here's a long winded but hopefully helpful write up I did a few years ago for just this sort of question;

_____________________________

Catching thermals is about carefully watching the model for disturbances caused by the air flowing around it and reacting to them. On calm days the disturbances will be weak and can be discounted as nothing unless you're on top of your game. On blustery days the signs can be violent to the point of trying to crash the model and quick and decisive control is needed both for survival of the model and to maneuver the model to actually trap and ride the lift as it goes by. The one common point is that a trimmed model does not suddenly go out of trim for no reason. The flight path is altered by some disturbance in the air. Often those disturbances are thermals.

First off, if you only fly in dead calm days then it's hard to catch lift. It's there but so weak that a newbie likely won't see it or it may be so weak that it doesn't hold up the model. Look for days where the wind is light to moderate and seems to be variable in both direction and strength. If it's mixed up like that then there's very likely therals around.

Launch the model and fly directly upwind so the model is about 100 yards upwind of the release point. Now gently turn the model so it flies cross wind but with its nose still crabbed into the wind so that the ground track stays out at the proper distance. Depending on the wind this means the turn may only be a few degrees or it may well be 80 degrees. When the model has moved about 150 to 200 yards off to the side gently turn it back into the wind and keep turning to re-establish the same crab angle for the return. Let it fly past the launch point and off to the other side. When it gets to the same distance on the other side gently turn back and repeat. This is your basic search pattern. Exciting, eh? (I'm Canadian, I'm allowed to "eh" )

The key is to keep it upwind the same distance for now. Alter the direction to keep this. And for all this turning the sticks should only be used with very slight motion. The more you deflect the controls the more drag you create. The key to efficient flying to conserve altitude is to barely move the controls and then wait the 2 or 4 seconds for the model to react. If you're not in lift don't be in a hurry to do anything. Rapid turns and corrections are high in drag and that wastes your fuel (altitude). Also keeping your inputs small means that the air moving the model will be more apparent. And it's the air moving the model around that is your indication of what is happening out there.

The most likely thermal interaction when crabbing back and forth like this is that the windward wing will suddenly lift up and the model will try to turn off the wind. Fight this with a strong turn back into the pushed up wing and turn into the wind. As the model banks over feed in elevator to maintain an even flight speed. Be quick and decisive here. You're potentially in lift and the gentle rule from above does not apply in this. You need to KEEP THE FLYING SPEED NEAR TO CONSTANT. A stall at this point is like loosing the fish off the hook. As you turn into the disturbance watch the model closely. The initial tendency is for a slight lift up due to all the corrections adding speed. But if it was not a thermal these actions will fade away within a second or two. If it is lift you'll see the model start to gain height as it turns into the lift. Let the turn open up and fly into the wind for a moment to see what is happening. If it keeps lifting then fly until you see it start to sag off and then carry through with your turn in the original direction to bring it back around into your thermal circle.

Another way to enter a thermal is nose first. The telltale signs for this option can be confusing as it depends on the model. I've had some models that tend to lift the nose and want to slow down and need a quick push of elevator to punch into the thermal and start rising. I've had others that like to lift up the tail slightly at the same time that they slow down and start rising. Again, the way to success is to fly your model a lot and watch it carefully to see what it's doing.

This is where you're elevator control comes into play. You need to fly a moderately tight turn with a 20 to 30 degree bank angle and use the elevator to restore and maintain a close watch on your proper flying speed. This is hard due to the apparent variations as the model turn into and off the wind. But if you use the cross wind portions of the circle as a guide you should be able to get it set pretty quick. I cannot stress how important it is to master the elevator control when soaring. It is your throttle. But unlike a power model THIS throttle only works if it has airspeed to work with. It is imperative that you use a quick and finely tuned stab of down if needed to kill any tendency to stall or suddenly slow down. If some gust or lift suddenly lifts the nose you need to be quick on the stick to jab in some down to lift the tail and keep the model on an even keel and at a proper flying speed. Thermals are often turbulent and to some extent you need to fight that turbulence to keep the model flying through it. But just as importantlly you need to be ready with some up elevator at the first sign of the model wanting to pick up the tail and try diving. A thermal or gust induced dive is like having a gas line on your car suddenly start leaking when you're in the middle of nowhere. You need to "plug that leak" quickly.

But what if the disturbance was not a thermal? Well, you reacted and turned into the wind but as you let the model fly a few yards upwind you see that it was just a little turbulent rotor or gust that caught your wing. So cut that cross wind leg short and carry through with a reversal back the other way. The model will still have a little bit of the upwind turn in it so it's more efficient to just work with the flow rather than fight it. You already lost a precious 10 feet or so dealing with the possibility that it was a thermal so cut your loses rather than loose more by returning to the original track. Damage control is just as important as finding a thermal. Same if you do find lift and start turning only to find that you turned the wrong way or are not successful in locating it within a two turns. Once you realize it's a lost cause just maintain a smooth turn until you come around into the wind. Fly upwind with a slight crab back to the centerline and when back out at the range increase the crab angle to maintain your 100 yard upwind line.

When in the thermal turn watch the model closely for signs that the lift is stronger on one side than the other. Also if you're not centered you'll find that on one side of your turn the lift tries to push the model away by increasing the bank. Use that disturbance to let the turn tighten and as it comes around and is pointed more or less in the direction the disturbance hit open the turn up to fly into the area of sky the disturbance came from. By watching and reacting to this stuff you should be able to center your turn in the lift. This is where the skill and handling comes into play. You need to learn when to let the turn open up and then close it down in order to place the model where it needs to be. But at the same time you don't want to use any more control input than is barely required. This means you need to start letting the turn open up a good 90 to 120 degrees before where you want it and to start closing it up ahead of time as well.

Thermals also come in lots of sizes and flavours. There's the big soft ones where the turn can and must be large and open. There's the little stovepipers where you either need to dance on your wingtip or fly through it for only part of the turn. And then there's some that try to push your model into a spiral dive and once you're cored you need to be constantly holding some outward control to maintain your position. Then there's those that need to have the model force its way constantly into them. You'll find all sorts so be ready to be reactive to the needs of the moment and always be watching the model for the signs of what the air is doing to it.

NEVER turn downwind unless you think there's a thermal or it's time to come back and land. Always make your reversals into the wind like a sailboat tacking. Gliding is by far the easiest method of learning to fly a model airplane. The models are gentle in the extreme to learn on. However, learning to SOAR is a whole other issue. Gliding is coming downhill while soaring is gliding uphill. Learning to read the air and truly soar is a skill that mixes a wide number of skills that must all come together at the same time and in the proper proportions. But when it all clicks and you find that you had the longest flight of the day in your group and in bad conditions you'll know that you got all you could out of the air that day and it'll be a great day to be alive.

____________

The above is based on flying out away from yourself. The dynamics change a lot for finding air if you're looking to hold onto the model and then side arm it into the air directly overhead. For that case the writeup in the first few posts of this thread suggesting that you watch for wind variations of direction and strength is the key. You also need to pay attention to the warmth of the air as it rises when a thermal is building and moving around you. Only when it's still attached to the ground or fairly close to it will you feel the signs that are "right" for a thermal to be overhead.

One final thing. A strong gust is often the "fill" adding to the general windspeed. The fill being the suction of the thermal that just passed by you. In that case the right option is to wait for the gust then sidearm or throw it up and move quickly to somewhere around 20 to 50 yards downwind of your position. That is generally where you'll find the thermal that just passed by if you read the rest of the signs right.
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Old Sep 19, 2012, 04:27 PM
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If the model is tearing around at high speed or diving, out of control, shut down the power. I know this is obvious, but I've seen people forget to do this on numerous occasions. I suppose that's not really a soaring hint except that broken models don't soar very well.
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Old Sep 19, 2012, 04:32 PM
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A wonderful analysis of thermal activity Bruce.
As an old free flighter of 50 years + and only flown R/C sailplane since 1973, I can confirm your observations. There is nothing more satisfying than hooking up with a good thermal.
After designing and building all of my own R/C sailplanes up to four years ago, I have fallen a sucker to Ukrainian and Czech ready built electric sailplanes which perform much better than my designs,
Most of the local club fly everything from speed to 3D stuff and are baffled as to why I fly sailplanes. It's like the comparison of sailing and power boats. To each his own!
We have recently been given access to the decommissioned Shearwater Airbase, which with its 10,000+ ft runway provides sufficient area to fly both Free flight and R/C without conflict. This has given us the opportunity to revive our Condors Model Flying Club which caters for Free Flight and R/C sailplanes.
The joys of thermal hunting are a wonderful experience and the skills developed in seeking and working the thermals are an inspiring experience.
get yourself a sailplane and get the satisfaction of natural flying.
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Old Sep 19, 2012, 06:04 PM
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Very, very, good stuff. Thank you all.

I learned RC flying at a great slope site in 1970 so it took me a couple years after moving to the flat lands to learn how to work lift. I have come to the conclusion that, when all is said and done, thermal soaring must be learned but it's very hard to teach. Hopefully we can help others by pooling our hints but, as has been said, there's no substitute for experience.

I just recently picked up the hobby after a long layoff and started out with a foam Extra 330. Once I got rid of the rust I quickly grew bored with aerobatics but I can fly a sailplane every day and the thrill of seeing the plane climb in a glide never gets old. Plus a nice, slowwwww, roll with a glider is more exciting than tumbling a powered plane. The only reason I had given up gliders in the first pace was because I moved away from my old flying field and I've gotten old enough that i don't much care for chasing a hi-start around. The new motor/battery technology has made that a moot point and I've found a lovely flying field just a few blocks from my home so I don't foresee giving it up again any time soon.

John. I haven't gotten my Czech dream glider yet but I'll be getting an uncovered TopModel sailplane for my winter project. I have an acquired allergy to CA so I don't care for building much but I've always derived great satisfaction from covering so it's a match made in Heaven. Besides which it would be very hard to build a kit of similar quality for the price. The Pulsars and Albatross are just a bit outside of my budget constraints so I'm planning on an Astra, Avia, Pegasus, or Siesta. Any thoughts on any or all of them would be greatly appreciated.

Thanks, again, guys!
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Old Sep 19, 2012, 07:01 PM
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Peter,
I fly with John O'Sullivan...we both have pulsar 3.2 REFs. Wonderful plane.
I also have a Topmodels Prelude...the +tail version of the Avia. Also a great flyer...its my full house plane.
Andrew
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Old Sep 20, 2012, 09:11 PM
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Great advice guys, I have a lot to learn. I have found the Radio Carbon Art DVD series help me too, though a lot of the stuff is very advanced..
Things like, if your are in a thermal, even a small one, don't leave it to search for another thermal that might not be there.
Making minimal control inputs to reduce drag.
I find that the higher I can get , thermals tend to get wider, so wider radius turns, are possible to stay in the thermal = less control input..
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Old Sep 21, 2012, 11:51 AM
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From many years of flying I have learned the following thermal facts:

The best lift is always directly in the sun where you can't see the model.

The best thermal of the day happens shortly after you put your glider in the car.

Birds always show the location of a thermal when you are too low to get there.

The winch always breaks down when its your turn to launch into the "hat sucker" everyone is flying away in.

And..... when you finally catch the ultimate monster thermal, your transmitter will be running low on batteries and you will have to pull out and land.
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Old Sep 21, 2012, 02:14 PM
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If you really want to learn about thermaling check out Paul Naton's videos at Radio Carbon Art. Its well worth the investment.

PS. I'm not affiliated with his company.
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Old Sep 23, 2012, 10:03 AM
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Hey guy's, I am new to this type of flying and so far am very enthused. I know that I don't have a "real" sailplane but it will do as a means of learning the basic's along with THIS very informative thread... I bought myself a HK Dynamic-S and have been having alot of fun flying it. It is so neat to climb quickly up to 1000' or so and cut power and see what I can do. I have been working on getting her trimmed so that it fly's well hands off. BYW, back in my old life when I was young and my dad was alive we spent alot of time in a beautiful sailplane a friend of his owned as my dad and him traded out my dad towing him in my dad's S.Cub. My dad was a ret. Army Air Corps and Airline pilot. Flying in the silence of that sailplane is and has been something I will never forget, it was like truly being a bird...all I could hear was the wind. Anyhow, I can see this type of flying becoming my new "line of work"... I am also so happy that I have a beautiful and powerful 80" Hanger9 Piper Pawnee "Tug" that my son likes to fly so that I can eventually get myself a full fledged sailplane once I learn more and find out what would be recommended. Great to have a fellowship of pilot's here that I can learn from and ask all those "stupid" questions.....That is how I learned to be a master shipwright...... as a young boy in the boatyard asking all those annoying questions, as to 'WHY and HOW"???????? Dave/ZZ
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Old Sep 26, 2012, 02:31 PM
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Welcome, zeezee.

Keep the questions coming. It's very easy for us old hands to remember what baffled us as fledgling sailplane pilots.
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Old Sep 27, 2012, 02:39 AM
If it flies.....I can crash it
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United Kingdom, England, Preston on Stour
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Quote:
Originally Posted by zeezee View Post
Hey guy's, I am new to this type of flying and so far am very enthused. I know that I don't have a "real" sailplane but it will do as a means of learning the basic's along with THIS very informative thread... I bought myself a HK Dynamic-S and have been having alot of fun flying it. It is so neat to climb quickly up to 1000' or so and cut power and see what I can do. I have been working on getting her trimmed so that it fly's well hands off. BYW, back in my old life when I was young and my dad was alive we spent alot of time in a beautiful sailplane a friend of his owned as my dad and him traded out my dad towing him in my dad's S.Cub. My dad was a ret. Army Air Corps and Airline pilot. Flying in the silence of that sailplane is and has been something I will never forget, it was like truly being a bird...all I could hear was the wind. Anyhow, I can see this type of flying becoming my new "line of work"... I am also so happy that I have a beautiful and powerful 80" Hanger9 Piper Pawnee "Tug" that my son likes to fly so that I can eventually get myself a full fledged sailplane once I learn more and find out what would be recommended. Great to have a fellowship of pilot's here that I can learn from and ask all those "stupid" questions.....That is how I learned to be a master shipwright...... as a young boy in the boatyard asking all those annoying questions, as to 'WHY and HOW"???????? Dave/ZZ
i found that the wings on my dynamic required a little twisting to reduce the amount of trim i have set....more trim=more drag....i have also moved my cg about 5mm back from the marked spots and found it glides much better and once on power it has a slight climb out....works for me.
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Old Sep 27, 2012, 08:43 PM
The Lone Sloper
USA, NY, Orchard Park
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Originally Posted by flystoolow View Post
The best lift is always directly under the sun because the ground is hottest there.
That happened to me today, caught a nice thermal and it headed right for the sun

Absolutely read The OLd Buzzard's Soaring book.
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Old Sep 29, 2012, 12:51 PM
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Here's another one I forgot.

Almost all motorized gliders will want to pitch the nose up with the motor on. The faster you go? The more it wants to climb. It just becomes second nature to push the nose down but there is another way. Just climb in a spiral. Adding some bank reduces the tendency to pitch up.

Keep the ideas and questions coming!
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Old Sep 29, 2012, 11:01 PM
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Originally Posted by zeezee View Post
Hey guy's, I am new to this type of flying and so far am very enthused. I know that I don't have a "real" sailplane but it will do as a means of learning the basic's along with THIS very informative thread... I bought myself a HK Dynamic-S and have been having alot of fun flying it. It is so neat to climb quickly up to 1000' or so and cut power and see what I can do.
snip
I am also so happy that I have a beautiful and powerful 80" Hanger9 Piper Pawnee "Tug" that my son likes to fly so that I can eventually get myself a full fledged sailplane once I learn more and find out what would be recommended. Great to have a fellowship of pilot's here that I can learn from and ask all those "stupid" questions.....That is how I learned to be a master shipwright...... as a young boy in the boatyard asking all those annoying questions, as to 'WHY and HOW"???????? Dave/ZZ
You may turn out to be an exception, since you have an in-house tug, but it is my understanding that the aerotow guys usually don't get to fly much at all due to all the logistics. I am not sure you have to have a scale job to have a "full fledged" sailplane. You probably do have to have more span, unless it's really sophisticated like a DLG. Go to charlesriverrc.org and look up the Supra and the Bubble Dancer in the articles section. I'd consider those "full fledged".

I always try to get beginners to build an Olympic II. (over at skybench.com, presently). As a master shipwright you should have no trouble with the building part. It's reasonably large, so things happen slowly, it stays up better, and it's easier to see. Plus the handling is very good. So you learn faster and when it's time to catch thermals you can devote more brainpower to figuring them out since you don't need as much for the mechanics of flying.

There are other decent choices but, of the ones I've flown and instructed with, the Oly II seems to be the best.

We have a boat builder in our area who has recently taken up rc soaring. He's doing quite well. And the stuff he builds is gorgeous.
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