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RC Gliders, Sailplanes and Slope Soaring Discuss rc gliders,rc sailplanes and slope soaring in this forum. Thermaling techniques, airfoils, tips, etc

First thermal?

Old 02-12-2006, 10:12 AM
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andy glider
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Default First thermal?

How long was it for you thermal guys before you caught your first one? I guess it has partly to do with picking the right days?
I have mastered the very basic flying now but i've yet to catch my first thermal.
Old 02-12-2006, 02:00 PM
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Default RE: First thermal?

Catching thermals is more about carefully watching the model for signs and reacting to them.

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.

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.
Old 02-12-2006, 10:42 PM
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Wide Open
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Default RE: First thermal?

wow, that was a ton of helpful information. now i cant wait to fly the fling (which i just finished by the way). ive flown real gliders and they teach you all the same stuff so im excited to see how that will carry over to model soaring.
Old 02-13-2006, 04:11 AM
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andy glider
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Default RE: First thermal?

Wow, thats one excellent guide to finding thermals! Thanks very much for your help! I can't wait for a nice day to go searching.
Old 02-13-2006, 11:34 PM
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Default RE: First thermal?

Well, the blisters on my fingers from the typing are almost gone.... Glad I could help. There's still a lot left out but by the time you get to try out what is above for a while you'll be able to fill in the blanks yourselves. Perhaps some of the others here will add to what I wrote to help fill in the blanks. Certainly a few of them have in the past. I'd strongly suggest you try some searching within this forum for keywords like "finding thermals" or "learning thermals" or similar and see what comes up.

Another excellent resource if you can find it is Dave Thornburg's book The Old Buzzard's Guide to Soaring. It covers such stuff as the low impact searching like I spelled out as well as many other topics. Like proper soaring the book is as much a philosophical "how to" about the most effective way to fly a glider as it is a detailed description of what thermals are like as well as how to fly in them.
Old 02-14-2006, 08:09 AM
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Default RE: First thermal?

thanks matt. when i really got to looking at what you typed i slowly started to realize that it was just like the soaring handbook (full size) that i have, except without the navigation tecniques! so i think its time to look in there for a refresher since i havent been soaring in about a year. hopefully ill be able to get the first flights on the fling this week so ill tell you how it goes!
Old 02-15-2006, 06:24 PM
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Default RE: First thermal?

having never seen a thermal flight, i would like to see a video.. anyone know links to pages that have videos of guys handlaunching into thermals?
Old 07-01-2010, 03:27 AM
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Default RE: First thermal?

http://www.youtube.com/watch?v=IZMZuYr5lDA

http://www.youtube.com/watch?v=KAs53d1kzPU

Two very clear launches into thermal, you can actually see the plane rising. You can also see the instability of the thermal (the video's were taken on a small island close to the Netherlands where it's always pretty windy). Browse youtube for more video's

(yes, Iresurrected this thread because it contains some very useful information!)

Old 07-01-2010, 11:29 AM
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Default RE: First thermal?

Other methods for finding thermals are watching the big birds (i.e. buzzards, hawks and vultures) searching for them. These birds know where to catch thermals. If you don't have the "luxury" of sharing your airspace with those birds, then look for low hanging smaller clouds. claouds that are kind of dark on the underside. These clouds normally produce good lifts. Or any dark surface on the ground, like large patches of woods. Cement and asphalt surfaces are good sources too. In general on any hot summer day there should be plenty of thermals to be found anywhere.
Old 07-01-2010, 02:36 PM
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Default RE: First thermal?

Indeed. Generally, just fly. The first time you catch a thermal you will be thrilled (just like each and every time after that
I caught my first thermal with my first easystar shortly after starting this hobby, that was enough to make me abandon everything smelly (gas, nitro) and concentrate on gliders...
Old 07-16-2010, 11:50 PM
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vh2q
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Default RE: First thermal?

What's the right technique for gaining altitude? Same tacking technique, or just power straight into wind? My Aspire, with Black Widow on pylon, has trouble punching into the wind.
Old 07-17-2010, 09:01 AM
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Default RE: First thermal?

Once you start getting 'into' sailplanes you'll be hooked! I do like many aspects of the hobby- even free flight- which is very challenging. A really great book that will stoke your fires about catching thermals is titled 'Exploring the Monster'- can't remember author. It's a GREAT read! Martin Simons has some great books with 3-views and the history of many types. Well worth the money if you are 'into' scale. Ride that 'Cumy' (cumulus clouds) Highway!
Old 07-17-2010, 10:51 AM
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da Rock
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Default RE: First thermal?


ORIGINAL: vh2q

What's the right technique for gaining altitude? Same tacking technique, or just power straight into wind? My Aspire, with Black Widow on pylon, has trouble punching into the wind.
Want the best technique for gaining altitude?

Watch the real pro's, the buzzards. They circle.



Old 07-18-2010, 12:31 PM
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vh2q
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Default RE: First thermal?

gaining altitude under power, I mean.
Old 07-18-2010, 01:36 PM
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Default RE: First thermal?


ORIGINAL: thevirginian

Other methods for finding thermals are watching the big birds (i.e. buzzards, hawks and vultures) searching for them. These birds know where to catch thermals.
I'll second that statement. My first thermal was where I always see Red Tailed hawks circling, now whenever I want to catch one I go this the same place and 9 times out of 10 even if the hawks aren't there I will catch a thermal there.
Old 07-18-2010, 11:03 PM
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Default RE: First thermal?

When climbing under power you are looking for max climb rate. Staight up only works for hotliners, most will need a less sever angle. Practice will tell you MUCH more than I.
Maintaineing adequate air speed is important. Forward motion lets the wing generate lift. this counts in thermals and under power.
When flying a new plane we often allow it to float or fly very slowly. Lift can hold the plane even sometimes but flying a circle with adequate speed lets the plane's speed work along with the lift for maximum results.

I thought BMatthews was quite excellent with his above post, well done!
Old 07-19-2010, 02:39 PM
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vh2q
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Default RE: First thermal?

Turning causes loss of altitude so my first instinct is to NOT fly in a circle while gaining altitude under power (unless in a thermal which is not likely immediately upon takeoff). Flying straight into the wind with some degree (how much?) of up elevator seems that it would result in a higher rate of climb. Tacking back and forth across the wind, turning into the wind, seems like the second choice. Turning downwind seems like a lousy idea. But I am a beginner when it comes to gliders so I probably have this all wrong.
Old 07-19-2010, 03:47 PM
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Default RE: First thermal?

My first thermal was with an Aerobird, a parkflyer. At the time I did not have a glider.  But once I got a taste, I ordered a glider.

Old 10-31-2010, 06:14 PM
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Default RE: First thermal?

I'm a full size glider pilot. We work off ground feartures such as large ashphalt areas, farm houses (i'm an aussie), roads, etc. Cumulus clouds are pretty much thermal markers. Anything that gets hot and holds the heat is a source for a thermal. The hotter the better. The birds are pros.. Without doubt

I have caught a few thermals in models and I'm hooked!

Best of luck
Old 11-18-2010, 10:45 AM
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Nor Cal Mikie
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Default RE: First thermal?

Once you get into your first thermal, you'll be hooked! I started off with a glow .049. What a mess. Never again.
Went with a DynafliteWanderer that I modified with aSpeed 600 motor to get about 4 mistakes high.
One power on launch and I startedlooking for lighter air. Cought aBIG one and in no time the Buzzardsjoined in the hunt. Even had Hawks tryingto run me out of "their" air space. Nothing like a Hawk hitting your plane. Talk about a thrill?
Lasted almost 2 hours. Good enough to put the raido on the bench and watch the plane keep going up far enough that if you blinked, you lost sight ofit. Catch a good one and see how close you can get to the bottom of the clouds. At least you'll have fun trying but you " just can't quite get there".
Even acheved Level 1 L.E.S. I don't compete so I'll probably never get any farther but it was fun getting there.
Been away from flying too long.Got the bug again and before too long I'll be at it again.
Old 11-18-2010, 11:21 AM
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da Rock
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Default RE: First thermal?

You actually can reach the clouds. And you will be very sorry that you did.

We had a rule at a previous glider club. When your glider is just two tiny dots you can say you have specked out. Of course, you're seeing two specks. The rule went on to say that when you only saw one speck it was time to lose some altitude.

One day we had cloud streets from horizon to horizon and BLUE blue above. Gorgeous day. Everybody was specking out. So one guy decided to reach the clouds. You know, it's really hard to fly a glider that just got sucked into a cumulus. Nothing to look at but cloud. Never found a trace.
Old 11-19-2010, 11:44 AM
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Default RE: First thermal?

I had been launching via high start a Gentle Lady, 2 - 3 minutes max or whatever it was, so long ago....

I was in N. Texas in some pastures. One time there happened to be some hawks circling, I managed to high start close to them.

Once off of the high start I started their way and could actually see the glider "bump" up! So after I got that visual I knew what to look for.

I have built more gliders than powered planes since then....

Old 11-19-2010, 12:05 PM
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Default RE: First thermal?

It wasn't my first thermal,but my most memorable  one that comes to mind.  I had been doing  mostly slope flying at
Torrey Pines and decided to take my Paragon out to the desert to give thermaling a try.  I launched using a heavy high-start and was hoping to be able to stay in the air for at least a  couple of minutes when I hooked up with a real boomer.  I went from about 300 ft agl to specked out in a matter of minutes.  One thing that I learned was that while spoilers are not needed for the most part on slopes, I sure needed them in this situation.  Alas I hadn't built them in and so I was without the advantages that they can give.

I ended up loosing sight of my Paragon (I was thinking I might have to rename it "paraGONE") when I spotted it again.  I managed to break free of the thermal and got it back down to about 1000 ft when I ran into another boomer and my plane was climbing without effort once again.  This cycle continued and after over an hour I finally managed to get it back on the ground. 

Lesson:  If a plane has spoilers in the design, build them in!!!!  Tis a far better thing to have them and not need them than to need them and not have them!
Old 12-31-2010, 08:37 PM
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Default RE: First thermal?

I have just started gliding, I have been at it for about two days and I caught my first thermal using a great planes fling! came off the Hi-start directly into it!! (talk about luck) and now im hooked! I already want to buy a bird of time! and about dozen other gliders!
Old 01-01-2011, 10:08 AM
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Default RE: First thermal?


ORIGINAL: planefreak123

I have just started gliding, I have been at it for about two days and I caught my first thermal using a great planes fling! came off the Hi-start directly into it!! (talk about luck) and now im hooked! I already want to buy a bird of time! and about dozen other gliders!

Well, don't let us stand in your way.

I wanted a Bird since forever. I think all the old guys do.

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