Finding Thermals for RC Sailplane Soaring

[@matijanovak3906]

regarding the tail lifting/nose down attitude mentioned at 9min when in thermal, and also tail down/nose up attitude mentioned at 34:30 when in sink is because your angle of attack changes. how, i didnt touch the sticks you say. remember, angle of attack is defined as an angle between airfoil chord and RELATIVE oncoming air. people usualy leave out this "relative" which is crucial in this case as your oncoming air is suddenly from slightly downwards and a nicely balanced and trimed plane will adjust to it to fly at aoa it was trimmed at, making it fly at different attitude angle as we can witness.

[@jgm911t]

You have to work at times to hear but overall as someone new to soaring this was great. I got a lot of good information out if this, thanks for posting.

[@lonezombieheart7808]

that sound quality

[@BigJimMartinGuy]

Viewer 10,000! Do I win anything?

[@peterden9076]

Very sorry to say, but the statement that a wing lifts up on the side of a thermal is a (very common) misconseption. You have clearly no experience with freeflight gliders: how would they ever fly in thermals on their own if they are constantly would bank away from thermals? The banking of a glider near a thermal is caused by the windshear near a thermal and the dihedral of the glider acting on it. It will turn the glider towards the thermal instead of away.

[@richarddarlington1139]

While searching for thermals, and one wing half rises, you have found the edge of a thermal. Turn in the direction of the higher wing. A wing with no dihedral will react the same way, would it not?

[@peterden9076]

@@richarddarlington1139 Some misconceptions are at the base of this: By drawing a thermal as a distinct circle, it suggests that there exists a distinct edge where air rises in the circle, outside not: this is not the case. Away from the centre there is a slowly degrading of lift until lift is 0. Over the wingspan of a glider, say 3mtr, even under ideal circumstances the difference from one wing to the other in ‘'rise’' is by far not as big as one might expect and while the glider moves is constantly changing. It is often forgotten that the glider moves at its own airspeed, the result is just a momentary difference of angle of attack. The glider may respond by: stalling if it is really a large increase of angle of attack, dropping the wing towards the centre, or tilting away just shortly, consequently side slipping en regaining a stable situation with just a slight tilt, adapting to the rising off the airmass and level out. Visual this lifting of a wing is hardly seen and results in just a bid of a wiggle. The real reason why gliders close to a thermal can lift a wing substantially is because near a thermal there is a strong horizontal movement of air towards the thermal, ’sucked up’' or suppleting the air moving up. This effect is observed on the ground as well, when a thermal passes, as the momentary falling of the wind, wind seemingly changing direction and after passage strong increasing of the windspeed. The moving glider experiences a sudden new gradient in the oncoming air. The outside wing (from the centre of the thermal) experiences on its dihedral an increase of angle of attack lifting the wing and initiating a turn towards the centre. But while turning it still encounters new shifts in gradients so this phenomenon stays intact, keeping the outer wing high and the glider circling to the centre. The glider slips sideways until there again is a balance of forces along its longitudinal axis. Freeflight gliders have large dihedrals and small tailfins that will accommodate this effect strongly, but RC gliders experience the same effect, although less. Even so, zero dihedral wings undergo this effect but much less (why zero dihedral wings have still a basic stabilising effect goes be-on this issue here) This explains why the U-turn approach, although based on a wrong idea is also successful. .

[@richarddarlington1139]

@@peterden9076 So, everything I've experienced first hand, and everything I've read by some of the best soaring R/C pilots in the world is wrong, but you alone are right? How much flying have you done?

[@peterden9076]

@@richarddarlington1139 Thank you Richard, I get those reactions a lot. May be you can consider having an open mind. There are a lot of misconseptions going on in in the field of model aircraft and flying because some phenomina seem so obvious and once ''explained'' are easely, without a critical observation, copied from one individal to another. Still it does not matter how much flying an individal has done, but how seriously someone has studied airplane dynamics and understand them. But you asked, with some hesitation I can tell you: My name is Peter den Ouden from the Netherlands. You can find me in the results of 1963, 1965, 1969 F1b World championships. Futhermore I have participated in 3 Europian championships, and have been Dutch champion F1b for 3 times in a row and one F1h. Nowedays I am flying Rc gliders of my own design and build for 30 years or so. And rest asured, I am not alone in being 'right', but because of reactions like this, we dont speak up that often..

[@richarddarlington1139]

@@peterden9076 And yet, I keep finding thermals. Just so you know, I've been building and flying model airplanes only since the 1970's. Rubber scale is a particular favorite of mine. R/C scale, pattern, and sailplanes are also a source of great satisfaction for me. As I write this, I'm building a Dave Thornburg Bird of Time, possibly for RES competition. We'll see, as I fly mainly for the pure joy of it. Although, I've toyed with the idea of competing in IMAC on more than one occasion. Cheers, from Las Vegas, Nevada!

[@danman4t4]

Horrible presentation. I was hopeful to learn but the audio is frigin ridiculous. Have you ever heard of a wearable microphone? Sounds like this was recorded in a warehouse with speaker at one end and the microphone at the other. I got about 10 minutes into it before my frustration level was through the roof. Sad.

[@berts6943]

That is exactly what I was thinking after a few minutes o watching. So sad that this, probably very useful, information was presented with such terrible audio.

[@markwest3150]

They could not record anything! Keep it up SBSS, I will take whatever you put up

[@tankogenonrcgroups9750]

I shizamed the whole thing with my brain