A arte do voo Termal - Dicas

Este é um espaço destinado tanto para as pessoas que gostam do vôo silencioso e tranquilo dos planadores quanto para aqueles que curtem a adrenalina do voo rápido e acrobático dos planadores de colina.
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Lambreta
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Mensagem por Lambreta »

Importante ler.
Dica de Bruno Pavani.

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Hi Ken,
Some tips...
Here are some things I have learnt over the years (mostly from trial and error and from other pilots like Joe Wurts, Carl Strautins, Alan Mayhew, Jim Houdalakis, Tim Lennon, Hugh Blackburn, Tim Mellor and many others) that make a huge difference, and it all applies to what I saw at the World Champs!

Tip 1, 2 & 3, Learn to read the air. In F3K there is not much time to make the right decision so you need to improve your chances of finding a thermal as quickly as possible. Joe won because he was the best air reader there (and some would say in the world).

Tip 1. Ground signs.
1. Get out with some (3) streamers on a pole and start to watch the air change. Start to predict where the thermals are and validate/unvalidate it with a launch and see if you were right. Do it a million times, then another million.
2. Find the 'Vector method' on the web. Read it, learn it and do it.
3. Practice
4. Trees, bugs, grass, flags, birds, dust, other planes. If there is abnormal activity then there is usually a thermal there.
5. Practice
6. Did I mention practice

Tip 2. Plane signs
1. Learn to read the air around your plane.
2. Tail up is lift, tail down is sink.
3. A yaw to the right means a thermal is pulling your plane to the left so turn left.
4. If the plane speeds up then the thermal is in front of you, slows down and it is behind you.

Tip 3. Thermals and Meteorology
1. Get the Radio Carbon Art DVD 'Thermals' and learn about the air around us.
2. Learn what adiabatic lapse rate is and how the air forms when the air is moist or dry. Cold or hot.
3. Learn how thermals form on the leeward side of large objects.
4. Learn that thermals are likely to 'pop off' over a row of trees or some tents.
5. Learn about inversion layers (there can be 3 different layers of air evident at the same time).
6. Learn to visualise the thermal and the air that is passing over you. What has the air been doing over the last few minutes and what does that mean for the air down wind of you?


Tip 4: Find a friend who has the same thirst for knowledge as you do, because it makes it heaps easier. Bounce ideas off each other, analyse your thought process and validate your ideas.

Tip 5: Flying techniques
1. Learn to be agressive and fly faster than best l/d to get to a thermal.
2. Learn to centre a thermal properly. Don't overpull the back side of a thermal or add flap during the downwind leg of a thermal turn because you will fall out the front of the thermal. Get the book 'Old Buzzards Soaring Book' and learn about the river of air.
4. All the top pilots fly on the downwind side of a gaggle and are often the highest in the thermal. I watched it happen a dozen times at the Worlds.


Tip 6: Learn the taks
1. One thing we found 'wanting' in the Aussie team was our lack of practice with 5x2min or Poker because we do not fly them very often. It is simply practice, practice and more practice. Fly all the tasks in your local competition.
2. Get the Master Class DLG video series from Radio Carbon art and Bruce Davidson (in #3 I think) talks a lot a strategy and task management along with a lot of other great tips and info.

Tip 7: Spend more time worried about Tips 1-6 than Tip 8 and you will be a lot better off

Tip 8: Planes.
I saw two trains of though with planes and both worked.
1. Joe Wurts had a plane for the different conditions. A super slow 'Black Magic' for the 'almost dead' conditions because it had great handling and could hook the tiniest thermal. He had a Concept Extreme 2 for the nice conditions. Then he had a Stobel V3 for the active conditions because sink rate means nothing. He flew it because it has a great l/d at speed and this means he could get to the lift faster and punch home through the sink better. Because the section was slippery he carried a minimal amount (45g) of lead.

2. Martin Herrig had one plane to do everything, the Salpeter. A great plane in the light to moderate conditions but it is not so good in the windy conditions, so his solution was to ballast it to 130g. Geroge (2nd) and Mike (3rd) both used this type of scenario successfully with the Concept Extreme 2 and Twister 2 respectively.

3. Both scenario's work and so fly as many different planes as you can to find a fit that works for you. If you are starting out then choose a single plane and fly the pants off it in every conition. For the more advanced, try a few different planes and find a good fit.

4. My take (others will have a different opinion) on planes from floaty to racy are:

Floaty: Black Magic, Twister 2, Salpeter, Stobel V2
All around: Concept Extreme 2, Polaris, Blaster 3.
Racy: Stobel V3, Steingeisen

As a friend of mine once said..."there is a good start! Come back when you have finished and I'll give you some more!!!"

Cheers everyone and I hope this helps,
Marcus
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Marco Aurélio
SD-10G/F3J Supra/DG808S 4m/Condor 3m/DLG Steigeisen... e uma zag
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Outro texto.

-----------------------

If one doesn't take the time to set up DLGs well, then one doesn't know how a well set up DLG should fly! One also doesn't have the practice at doing it, so it becomes a hassle and takes a lot of time. And the results are uncertain. That is because plane setup is a skill just like any other. It becomes faster and more automatic with experience. You won't get that experience without doing the work!

In the vast majority of the cases where someone puts their transmitter into my hands, the plane is set up sufficiently poorly to hurt the pilot's performance.

The throws you want may not be the throws wanted by someone else. Take a plane setup by IMAC pilot Jim Cokonis (ShadowFalcon). Is his plane fairly well set up? Yes... If you only want to move the sticks about an eighth of an inch for normal maneuvers. He has the skill on the sticks to do that with precision. Do you? If not, then his well set up plane would be poorly set up for you. The less precision you have with the sticks, the more toned back you need the control response to be, so that you can maintain adequate precision in flight.

Let's look at rudder throws for example. It turns out that the efficient range for rudder throws is about 13mm or about half an inch. Beyond that, efficiency goes to garbage. Amazingly enough, that is pretty true regardless of the percentage chord of the rudder. That was a surprising result from one of my analysis threads. So one could set up such that rudder throw is only a half an inch. Or, one could set up an inch of throw, but except for real emergencies, only use the inner half of that throw range. Both options could be considered well set up; it depends somewhat on how the pilot will use it. If you like to play close tag with trees, then you likely need that inch available. Otherwise, you'd likely be better off without it. When it comes to using rudder, it is better to use a little too little than a little too much. Having reduced travel available helps prevent over-ruddering.

CG is another one of those things... Some pilots make a study of how their planes fly. They can keep the plane flying efficiently regardless of conditions and regardless of CG setting. Other pilots have no clue. They need the plane to be fairly pitch stable to make up for this. Also, "optimal" CG position is a function of turbulence level, as are optimal airspeeds (more turbulence -> fly very slightly faster for same camber setting). That's just a minor fact of life in the Reynolds numbers range in which we play. The neutral point is not a static point for us. The behavior of our wings is not a constant. So there isn't a single perfect CG setting either. Even the range of desirable CG positions may change a little as conditions change.

Some manufacturers provide good guidelines for things like throws and CG. Others provide essentially no guidance. But in any event it is a good idea for pilots to have enough confidence/skill at the sticks to be able to safely fly the plane regardless of settings. It is also a good idea for the pilot to have the skills in plane setup to then be able to fix it so it flies well.

Heck, one should be able to take a mystery plane and get it set up reasonably well fairly quickly. That would still be set up better than the vast majority of planes out there. Then, fine tuning takes more time and familiarity with the plane.

For instance, take mystery plane. Let's say the pilot is pretty good at the sticks, smooth, and doesn't over-control the plane. So, let's set fairly conventional starting throws of +/- 3/8" aileron, +/- 3/4" rudder, (assuming top mounted stab) as much down throw as one can get without hitting the boom, and some reasonable degree of up throw - lets start at half an inch to make up a number. Put the starting CG about 3" behind the leading edge of the wing. Set the elevator trim to be parallel with the boom. Now the plane should be flyable regardless of the model. Perhaps not easily, or hands-off, but flyable.

Set the camber in cruise. Lacking info to the contrary, that is where the upper surface of the wing near the root is fairly flat across the hingeline.

Give it a toss and trim elevator so that it will try to fly hands-off.

Now launch it and get a little altitude. Put the plane in a vertical dive and let it build up some speed. If it pulls up, then give it some down trim. If it tries to go inverted, then give it some up trim. Now we have a trim position that would be somewhere in the ballpark for pitch neutral provided the CG was set approximately at the neutral point. Yes, there is some handwaving and some caveats here but it should be close.

Now, add a few clicks of up trim (perhaps 3 but how much will depend on the servo you are using and on whether or not you set up the transmitter such that each trim click moves the servo - which you should have done). Then leave trim alone... Adjust CG in minute increments until the plane is flying at a desirable speed for cruise trim.

This method somewhat decouples the elevator trim question and the CG location question which is why I presented it as an alternative to the classic methods. It should get you in the ballpark pretty quickly which is the point of the exercise.

Now lets look at response rates in roll and pitch. If the plane is super responsive in pitch but dead in roll, then increase aileron travel and/or reduce elevator travel. Get the plane to where the pitch and roll response seem to be at the same rate as one moves the sticks. One can generally set this in the dual rates setup, even if dual rates are not turned on by a switch. That is, one can use the same rate for all flight modes/conditions. I advocate that - less to mess with and mess up as one flies. Our DLGs don't really have a wide enough speed range to need multiple rates. If you have to mess with the travel adjustments you might have to re-visit the elevator trim as the servo can end up moving a little depending on your luck.

Next, lets set up pitch-neutral roll. In level flight, roll back and forth quickly over shallow bank angles. Make sure you are using only aileron to do this, no elevator! If the spring tension is not high on the sticks, chances are you can't do this well enough. Now, if the plane gradually pitches down, increase the differential slightly - make the down aileron go down a bit more and the up aileron go up a bit less. If the plane pitches up some, then do the reverse. Note the plane will likely slow down some during this maneuver but that is NOT the same thing as a pitch response. Making the plane move costs energy and that is paid for by either altitude (potential energy) or speed (kinetic energy) or both. What you want to watch is the angle of the tailboom (or whole fuselage) relative to horizontal. You don't want that angle changing.

Is this where you really want your differential? If you are a beginner/intermediate pilot, then I'd say yes. If you are advanced/expert, well then it is your choice. You should have the skillz to deal with the pitch change induced by aileron input.

Now realize I'm not an advocate of aileron->rudder mix. It is wrong more than it is right IMHO, in terms of percentage of flight time. But let's assume you want it. So this is when you'd set it up.

Go back to the small quick rolls. Watch how the fuselage changes pointing direction, left and right. When the plane is rolling in the clockwise direction, then the fuselage will yaw to the left. And vice-versa. So add a little aileron->rudder mix and check the results. Dial that mix until the fuselage maintains a constant pointing direction during the shallow roll maneuvers.

BTW, will this give you an axial roll? NO! It will just start out close to axial so it is not bad for initiating rolls from level flight. The required rudder correction direction is reversed when the plane is flying inverted (reversed at the sticks that is)... As I said, automatic corrections are wrong more than they are right. You can't beat skill at the sticks. But, you're the pilot. You pick your poison and take your chances.

Now, add in a mix for elevator->camber that adds perhaps 2mm down flaperons for half stick up elevator. It's just a starting point anyway. What you should find is that now the plane is suddenly a lot livelier in thermal turns and climbs more easily.

Now go do the loop test and dial in the up elevator throw and the elevator->camber mix. http://www.rcgroups.com/forums/showthread.php?t=1234569

At this point, the plane should be flying pretty well in cruise mode/condition and should thermal fairly well. It should be smoothly responsive on the sticks.

Now go ahead and duplicate this setup to create speed+launch and float flight modes/conditions.

For speed, adjust the camber to be 2mm up from where it was for cruise. That's a good starting guess if one doesn't have the info for that wing.

For float, adjust the camber to be 2mm down from where it was for cruise. Again, just a good guess lacking data for the wing. If Edge, go 1.5mm for starting.

Fly the plane in each of these modes, and trim the elevator to adjust the speeds. Don't bother trying to trim float if the air is not smooth while you are doing this setup. It is too difficult.

Now set up a launch preset. This would just be a couple mm up elevator added to the speed mode. Adjust for a nice pitch response on the throw.

Perhaps one can invent a quick and dirty test for how much elevator to use. Put the plane in a near vertical dive in speed mode from perhaps a quarter above launch height. Hit the preset button as one has speed approaching the ground. Make adjustments to get a good compromise between speed retention and altitude loss from when the preset is hit. Or, even better, use an altimiter.

For float mode, which is a thermal mode (cruise being the other thermal mode) reduce the elevator->flap mix for up elevator and down flaps. Since the flaps start farther down, there is less margin for them to go lower. For a starting guess, cut the motion in half.

For speed mode, probably just go ahead and cut the elevator->flap mix in half, both directions.

Ok, now just go and fly the plane for a while in a variety of conditions. Fine tune as you see fit.

Gerald

PS - Forgot to mention about dialing in landing flaps, but I covered that anyway in the sticky thread. This post duplicates a lot of info from that thread anyway, but perhaps with a bit more of an at-the-field perspective and doing things slightly differently in a few cases. There isn't one single approach that works. But doing things in an appropriate order really makes the job a lot easier!"

___________
Marco Aurélio
SD-10G/F3J Supra/DG808S 4m/Condor 3m/DLG Steigeisen... e uma zag
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Dedé
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Mensagem por Dedé »

Uma ótima dica para quem quer voar térmicas é:

TENHA UM ÓTIMO PLANADOR TERMAL e aprenda a voar este planador.

Caso contrário toda esta teoria e manhas não ajudam muito, apesar de serem também fundamentais.

DD
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Mensagem por Marco Aurélio Olivetto »

[yt]OV4H-UgATXE[/yt]
Fantasma
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Re: A arte do voo Termal - Dicas

Mensagem por Fantasma »

Valeu Sergio.
Muito boa suas orientações, por mais que ja voe planadores essas suas dicas vem enriquecer o nosso voo.

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