RC Basics: How to find and hook a thermal

[@jimmbbo]

Another great, helpful video, Bruce! A couple of thoughts from 20+ years of full scale and model soaring - A thermal forming with a prevailing breeze will tend to drift with the breeze, so searching for lift downwind of a dark field or asphalt parking lot can be productive. Also, the thermal's rotational axis will "lean" downwind. Visualizing those events can assist in finding lift. Watching the surroundings is helpful for visualizing what Ma Nature is up to, especially if there are trees, water, flags, banners or dust devils in the area On many models, flying directly through a weak thermal may not be immediately evident, and often is indicated by the tail lifting as the thermal strikes the glider. At that point, turning downwind often allows the model to find the thermal. If there is no prevailing breeze, the direction of turn is a 50/50 proposition. A caution for models with stabilizing systems like AS3X is that the stabilizing system masks the normal indications of encountering lift. Instead of a clear wing tip or tail lifting, the model may simply start bouncing around as the stabilizing system counters the upset. FWIW, the normal lapse rate for atmospheric cooling is approximately 2 deg C or 3.5 deg F per 1000 ft. FFWIW, a real "gee whiz" bit of info is that subtracting the dewpoint from the temperature and dividing the result by the lapse rate yields an approximation of the cloud bases above ground level in thousands of feet. e.g.; if temp = 25C, dewpoint = 15C, 25-10 = 15, and 15/2 = 7.5, or 7500 AGL Cheers, mate! Jim

[@kcstart6265]

jimmbbo All of your variables are metric. Would that mean the altitude is meters? Great information, Thanks

[@xnoreq]

​@@kcstart6265 spread = temp - dewpoint [in °C] (a high spread means dry air, a low spread means moist air, a spread of 0 means 100% relative humidity) cloud base = spread * 122 [in m] cloud base = spread * 400 [in ft]

[@slam854]

I just acquired a motor glider of 2 meters and a second of 1.5 meters. the 2m is 3ch while the smaller is 4ch. Just renewed my AMA membership and FAA licensed the craft. I joined the Utah Valley Aero Modelers with meeting at the airfield tomorrow night. After official business a night flying session will begin. Thank you for your very good information which is sure to be quite helpful. We have very good terrain for slope soaring.

[@elfkind5590]

You're reading my mind! I've been watching glider videos all day, free energy is fascinating!

[@Tsnafu]

Are you considering selling any of your artwork Bruce? ;-)

[@FinalGlideAus]

Ahhhh man I miss gliding. Got excited seeing your last video with them in the sky.

[@RCModelReviews]

Yeah, we get several full-sized gliders dropping in each summer and it's always great to have a chat with the pilots. I also installed a FLARM receiver connected to GliderNet in my workshop to help them out. If you're around these parts at any time I'll see if I can organise some flying time at one of the nearby glider clubs for you if you want.

[@iflylilplanes]

Chad, We get a lot of full size flying out of Camden, some fly over the turf farm where we fly RC in Elderslie west of Sydney. I understand there is a quad racing club in the area as well, hint.

[@jack00scarecrow]

was FliteTest your last glide :) or have you had a go since then ?

[@scottthompson2481]

Thank's so much Bruce , Im building a DLG for this summer , so it's great to have this advice to let me now what to look for to get me going . Many thanks Bruce , all the best mate .........

[@LA6UOA]

This is a great tutorial! Thanks, Bruce! One thing is maybe missing: The thermal that rices where there is a steady wind blowing. That's also great fun, having the plane standing like a kite and going up in the bricklifter thermal! Standing still, because the wind is blowing at or over the aircrafts stallspeed. The thermal will then be tilted to one side. Keep up the great work you do for the hobby!

[@MoiraOBrien]

Great video Bruce. There was one thing you didn't mention and that was that the thermal will move with the prevailing wind. You can thus use the fluffy clouds to predict where the thermal activity will be by looking upwind of the cloud. By the time the air has risen to condensing altitude it will have moved some distance downwind.

[@danielburke6536]

Excellent tutorial, thermal gliding is one of the best forms of flying.

[@Moethebro123]

So I also fly manned gliders and I learned something from your video! Just one remark: remember the air goes down again on the sides of thermals!

[@Paul_C]

Which is why you start with water, and land without. You just shift your sink curve to the right.

[@dennisrichards9480]

" where there is sink there is lift"

[@Arthur_C]

Thanx Bruce! More info on the coriolis effect etc. is much appreciated. Especialy your hints and tips on recognising thermals is most welcome!

[@coinholeo2253]

Yes,still awake at the back!Gave me a bit to think about.Thank you!

[@brucestevens2488]

great video, been flying sailplanes for a few years now and learned a sig amount of info today, Thanks!

[@WarblesOnALot]

G'day Bruce, Yay Team ! Well put... We spent a lot of time discussing Thermal Spin Direction & Corriolus Effect versus Landscape Topography & Wind-Direction, back in the early & mid 1990s ; when in the Pub after a hard day Aerotowing Hang Gliders with a 3-Axis Ultralight, the prototype Bailey-Moyes Dragonfly... The consensus among the Hangies was that anywhere from 15% to 20% of times the Thermals must be spinning "backwards", but the rest of the time then turning to fly against the "statistically-predicted" direction of the Therrmal's Corkscrew gave higher rates of climb via slower Groundspeed, tighter "coring" of the Lift with less Bank required & thus a larger Planform perpendicular to the available Lift. Much booze was drunk over the years, comparing notes, but that was the consensus, from memory. Have a good one, ;-p Ciao !

[@stofffpv3128]

thanks just discovering the wonder of gliders..so been looking at lot of videos..yours very clear and mentions things that others dont seem to..

[@Captain-Nostromo]

A few years ago I was flying My Kyosho thermal glider in South Sweden Skåne 'scania' the thermal Wind was so strong that I lost the control off the plane and it was sucked in to the Clouds Even if I try I couldn't Dive out of it, about a month later I got a call from a farmer in Denmark telling me that he has found the plane, I told him to send some pictures of it and it looked intact, so I Drove over the Malmö/ Copenhagen Bridge to meet him and collect my sailor. He didn't want any reward and just thought it was a big fun. The moral of the story. Always put a name and telephone number tag on your aircraft You never know what's gonna happen. 😀

[@gsansoucie]

Wonderful timing as spring has sprung up here in the states. Dusting off my DLGs and gliders.

[@MassivaMusic]

Guys, get into DLG! It's so much fun and so pure. Although i'm a beginner my other planes have no more use and get sold one by one. Feeling the plane, catch the thermal and losing it is frustrating and fabulous. @ Bruce, The second video of why to fly in a certain direction to the thermal would be greatly appreciated. And the advertisement url on your shirt leads me into a blank page.

[@barrygiblett5823]

-2 deg C /1000ft, thanks Bruce, very good, can't wait for part 2 ... left of right, ...

[@jfrede1976]

Hopefully we can get a live demo of this in the future would be nice to see someone searching themals and tell us what he is thinking at the flight.

[@unclefester420]

now you have to discus, get it, camber, crow and when to use them and maybe some set ups. I've been flying a calypso and others and catching your first thermal will give you goosebumps. more Bruce. Waiting patiently.

[@JakeBullit123]

very timely as I just bought an ASW28 for FPV,cheers.

[@Smt_Glaive]

wow...this morning I ordered carbon fibre rods and balsa to make a glider...and now this wonderful video..👍

[@navigator902]

Excellent presentation Mate.... been flying my Hobie Hawk for years now and thermals are the best....Cheers....

[@FlyingMerf]

I enjoy thermal flying and thought I knew thermals, but you taught me at least a couple of things I did not know. Great stuff!!!

[@familiekasman7413]

Nice video with clear and simple explanation !

[@hansleatherby1032]

Nice video Bruce - no glazing over for me! keep them coming

[@cbluebeard]

Thanks, Bruce! Looking forward to pt. 2.

[@aerowings9027]

Really well explained! Great video, love the enthousiasm. However, there's one thing I would like to correct, it's about the thermal getting wider at higher altitudes. The thermal doesn't really get wider due to centrifugal forces, maybe just a little but that's negligible. It actually gets wider by the lower air pressure around as its altitude increases. For most of us known, the air pressure decreases with increasing height. So when the bubble of air rises at the same time the pressure difference rises. This will result in an expanding width of the thermal. I know this has nothing to do with actually using the thermal inflight. But still I wanted to get my thoughts out (-;

[@jgruppe27]

Great video Bruce. Can't wait for Part 2. Love the channel by the way.

[@patrickcol]

Excellent video as usual Bruce, and I loved the grammatical instruction.

[@JimN5QL]

yeah, what's with that anyway?

[@kyus1974]

Good info Bruce. A big issue i see with a lot of people is setting their plane up nose heavy, which makes it very hard to read the air its flying through.

[@BrianPhillipsRC]

Great info - Thanks for your help!!!

[@M0rdH0rst]

I'm a big DLG fan too! :) A couple of weeks and I will see, if I got something of that lecture. Last year I got a lot of flight time out my 2 DLGs. A couple of 20 minutes-flights even. The birds in the area are watching me and come floating, when they see, I got lift :) I am currently scratch-building a bigger lightweight glider with "electric thermals" build in. It can carry a camera and then I can look those birds in the eyes :D It will also have a variometer so I get notified when it goes up or down.

[@lemauz.]

I'd mention thermal drift, generators and triggers and the use of 'varios', but rules and regs. change so much it's not worth the fuss. I'd say you have it pretty well framed. Good one, Bruce.

[@ranashome24]

Excellent explanation. Thanks. You have an artists hand The spirals are the proof. Please do a video for powered larger gliders

[@PugetSoundFlyer]

Thanks for this great introduction. Really well illustrated - especially the glider :)

[@Heli4213]

Besides the plowed field what else is best to go over? Open field? Roads?Roof?

[@GraemeDJ]

This is very informative. Please do a part 2. Maybe you could add a few clips of your old video of your 7 minute HK versus DLG flight to show us how it's done. Just a couple of questions: do thermals always rotate in the same direction and is there an optimum time of day to fly e.g is it better to fly a DLG mid- afternoon after the ground has been heated up for a longer period compared to mid-morning? Thanks.

[@Stambo59]

After watching this video the other day, I walked outside and saw a couple of hawks doing exactly this. Instead of the usual quick look I actually sat and watched them for a while. Must have been a fairly large thermal as I watch them cover quite a large area with not a wing beat in sight. Was quite fascinating. :-)

[@richards6246]

Reminds me of my ground school days... very well done!

[@chrisj800]

Thermals low down tend to be self centering as the wind being sucked in from all sides also moves you towards the centre if you maintain a steady rate of turn. Contrarily when high the thermal broadens but the self centering effect can disappear and you need to work harder to stay in the thermal core using a thermal technique that works for you. This can include tightening or cranking up the turn when in the strongest lift or easing the turn or even straightening up a few seconds when in the strongest lift before continuing the turn. A yaw string can be used to help picture the air being sucked in from the sides and turning into the gust with lots of rudder can centre the yaw string and centre in the core.

[@stevecraig3004]

What a great video! As entertaining as it was educational! All your videos are fun to watch...

[@chiro30]

Spot on for my main flying interest...one request....MORE please. TTFN

[@nlcirque]

Thank you. This was very good information.

[@gygaxthegoat2491]

excellent stuff thanks Bruce. You offer much more useful and straight talking descriptions than Joe Wurts video i have. great computer graphics too mate. happy flying :)

[@Skydive4ever]

Awesome video Bruce. Very well explained. If you have more to teach about thermals, don't be shy to do another video :-)

[@robertvanhousen1015]

Nice video. Which video discusses thermaling using the coriolis effect?

[@scottfirman]

In the summer,I can usually count on plenty of thermals to play with. Smaller RC powered rc planes can benifit greatly from thermals,especially over our mobile home park. Those trailers produce a ton of lift along the edges and over my flying field right next to it.

[@montanacrosses]

Help me Bruce!...The low pressure area is directly under the thermal as it rises? High pressure air rushes in to fill the low pressure area? This is right at 4:56 of the video and then on in the explanation. I teach flight as it relates to birds. I really want to get this little tidbit right in my brain!!

[@franklee90]

Its simple but great !! Thanks Bruce !

[@agennello1]

1. Is it better to yank and bank or rudder the thermal turn? 2. Is it better to turn counterclockwise or clockwise in the northern hemisphere?

[@donwood7700]

Excellent video as always Bruce! Two comments: First, If you were in the US, it would be practice.Second, it would seem to me that thermals lose their energy as the altitude increases. I say that because energy is expended as the thermal heats up the surrounding air. Thus, as the altitude increases the thermal gets weaker and eventually would not exist. So, I would expect that in your last example of "light" lift. The maximum height that one could reach (using the same glider) would be less than if the thermal was "really powerful". I think that would be due to the conservation of energy (anyway, that is what my engineering mind tells me).So, am I right or am I wrong?I am new to this gliding fun. I have a UMX Radian, Radian Pro (needs to be repaired), Radian, and Radian XL. They are all way cool and way fun!Keep up the great work!Don

[@samgu619]

Thank you, man. I learned so much.

[@mick7sp]

An old wise man once told me: _"Thermals are an act of god, but the landing is your own dam fault."_ :)

[@Memento86Mori]

nice one

[@franklee90]

Nice !!

[@alexyt4434]

True true for me

[@mazpr2025]

Its your own damn fault if you dont know how to write.

[@anbu94]

@@mazpr2025 said the man who edited his comment

[@jhardiman3]

Bruce, thanks for the great video.

[@alexyt4434]

Thanks for the information! I am a new RC pilot of a Radian glider.

[@pnaton]

I'm a fan Bruce, but your thermal information given here is full of errors: There are no thermal 'bubbles', energized air rises in streaks and columns. There is very little thermal rotation either near the ground or aloft. Any rotation at all is driven by ground aerodynamics and asymmetric vertical motion in the rising air. Thermals are not influenced by Coriolis effect, they are too small a mass. Wind speed tends to INCREASE as the thermal moves away from your location and opposite of how Bruce explains it. Also, wing banking away from thermal is not a reliable method as thermal edges are diffuse. Dust devils are the compressed inflows at the bottom of a large thermal much higher up, and spin in what ever direction as they are not coriolis influenced. Yes, air flows into a forming thermal and causes a wind shift you can use to find low levels thermals. Got that right. And practice too.

[@isoldemarangelis5096]

Great tutorial, always enjoy your work

[@MrFowl]

Very much appreciated! Great video. I look forward to seeing more glider flights in the future

[@richards6246]

Great Video Bruce!! Where is the second half of the video? On coriolis....

[@mitchsmith71]

Great video!!

[@theartandscienceofflight9239]

Hi Bruce - great video. Not too much flying in Canada at this time of year. I was wondering how you seek thermals when using a flight controller? Do you have to be in manual mode to see the wings rocking? Or is there another way to find the thermal? Thanks!

[@daftnord4957]

what are some good ways to manufacture a place for thermals

[@userTJ39780]

Hi Bruce (XJET), how are things in Tokoroa?

[@bacillo68]

Thank you for your videos. I really appreciate them.

[@maliniaravindan5349]

Sir, could you please tell me what would be the temperature difference inside and outside the thermal? Is it significant (greater than 5 degree celcius) or insignificant (less than 2 degree celcius)? In case it's significant, can it be sensed using Infrared camera sensor? Also will the speed of the air spinning inside the spiral thermal be higher than the air surrounding it? Thank you in advance.

[@dwexoticmaple]

so should you use alieron or rudder. and should keep nose attitude down?

[@TheStickyBusiness]

Very interesting. I really hope you upload part 2

[@malcolmeccles3783]

Thankyou for this video. I enjoyed it.

[@saggynun1802]

Awsome video I paragliding as well as fly quads and got a dlg recently can't wait for summer to arrive now. Looking forward to your next installment. I think you could talked about how to paint a white wall white and I'd still have to listen 😜

[@peterpanizza4320]

Thanks Bruce been following for a while, thought this one was a great info session!

[@frankv3864]

Great learning video again :) I like the white board stuff. But this one confuses me also a bit: what goes up, must come down. where is the air going to? And how big is such a thermal in meters approx? Cause when the wind is from South in Europe, there couldn't excist thermals in New Zealand:) A nice practical video IRL would be nice too :)

[@Memento86Mori]

thanks, sir it's good to learn by one who is in the hobby for long time

[@brianshangar7129]

Thank you for the interesting video s. Michigan,USA

[@tramsgar]

Thanks, Bruce!

[@GaetanVrprtn]

So interesting!!! Wonderfull if you can doing some videos with camera onboard and explain it in the same time! Great job like always !!!!

[@wordreet]

I had been wondering, but I see now that the entire thermal contains lift, with no dead spot in the middle. I caught my first ever thermals about 3 weeks ago. WoW one in particular just didn't fail until I reckoned I had gone far enough down wind. And again last weekend though I didn't manage so well. One of the things I love about flying RC is, just as when I was making a lot of kites, every day and in fact every minute is different! . LoL! First time you spelled practice the English way, then you spelt practise the American way. ;¬)

[@admargodoy]

Great thermal lesson. Until now I thought that when my glider moved alone it was because the thermal was pulling it in. :))))). I always try to guide myself through the vultures. But they do not always appear. A curiosity: One day I was watching one of these birds circling the top of a large cell phone antenna. He stayed there for a long time without moving his wings. I got tired of looking at it for so long. I wondered if these antennas generate heat from the microwave. Enough to generate thermals but not to the point of cooking it ... :)))))

[@vonSchwartzwolfe]

they do make heat. Also they are a BIG pile of steel with lots of area for the sun to heat up

[@admargodoy]

Ron DuBray I forgot to mention. They flew no more than 5 meters from the top and circled the tip of the antenna.

[@admargodoy]

makes sense

[@maartin111]

any tall object that stands out will trigger a thermal.

[@mediamonitor980]

Admar Godoy What you are talking about is dynamic lift - it's not a thermal but it will allow you to rise just the same. Dynamic lift is literally just air moving over and rising over a physical object like a tall building, a grove of trees, mountains, or an bluff along the shoreline.

[@lw216316]

A question - please sir - I'm new at this and fly a UMX Radian with small motor. The motor draws current from the battery and the controls draw current from the battery. I'm guessing the motor draws a lot more current than the controls. So when I'm in a thermal how long will the battery last just using controls and no motor? I know the answer is - it depends - so let me provide details to get a more specific answer I usually fly 10-12 minutes on my battery and so far I have only found a little help from thermals. I come down so as not to hurt the battery by running it too long. If I find a good thermal and stay in it a long time how much can I extend the 10-12 minutes by only using the battery for controls - turns....? Maybe another way to ask this is - if my motor takes 100 percent battery then what percent do controls take? a wild guess - 10-20 percent ?

[@irvine40]

Great video, classic Bruce!!

[@rusack7174]

Excellent presentation Bruce! Where does one catch thermals with a quad? :)

[@nicktk]

you can catch thermals also with a brick...it a matter of efficiency to be solved :)

[@MF-og1ct]

Thanks for this video! Very informative!

[@darryljmathews]

Great explanations

[@jh1982a]

Awesome video !!! Thanks

[@SamFugarino]

Thanks Bruce, good stuff

[@helierez]

good stuff. are people using variometers yet through telemetry? would be interesting topic for part 2

[@jimmbbo]

I installed a Spektrum vario and TM1000 telemetry module on my Calypso using a Spektrum DX9 and it is absolutely fantastic.. No sense flying without it when the glider starts getting tiny. Last year caught a thermal to 1740 feet AGL. The glider was getting too small to see, so called it quits. Do some research on RCGroups.com for more info. Vario www.spektrumrc.com/Products/Default.aspx?ProdID=SPMA9589 TM1000 www.spektrumrc.com/Search/Default.aspx?SearchTerm=tm1000

[@roberthosterman9575]

Do thermals bend ? Do they rise at an angle.

[@rfcpilotaus2308]

G'day Bruce Me and a few mates are glider addicts and glide any chance we get but we don't fly DLG we fly giant aero tow gliders with 3.6 - 6 meter wingspans and all but one glider seem to be thermal magnets because the Dg500 is a bit of a pain in the backside to keep in the air because it tip stalls really bad and doesn't seem to want to catch thermals, idk if it's just me but I can make everything else fly up and over 3000ft from aero tow drop off at 500-750 ft. I thought you might know what the problem is because you've been doing it for way way longer than me and I'm still young and stupid haha. Cheers from Sam :)

[@vonSchwartzwolfe]

there might not be enough or to much washout on the wings. I had one plane handed down that had to much and it had down incidence at the tips and stalled in every turn.

[@Mr.Laidukas]

+RCModelReviews Very informative video, nice! Want more, I built DLG for upcoming season. Please do second video on the topic.

[@leighfpvk8176]

Bruce, timely video, any chance you have a design for an Rc variometer? I don't have a taranis. I know rc hacker did one a ways back, but I thought there might be a newer style...

[@Len02013]

Leighfpv k have a look at www.rcgroups.com/forums/showthread.php?1749208-DIY-simple-and-inexpensive-Arduino-based-sailplane-variometer Works well, I put the audio into the video feed. But ended up removing it and just using APM and osd, can set up osd to have rate if climb etc and it's very similar

[@leighfpvk8176]

Len d Thanks Len, I have seen this one in the past, I was hoping it may have been simplified with the advent of new tech... cheers

[@Len02013]

Leighfpv k it's pretty simple, for memory all mine was arduino, ms5611 and 2 resistors, so 4 parts in total

[@selewee4809]

Impressive as usual, but MAJOR question: On northen hemisphere, in thermal, turn glider left or right for better performance?

[@old-timeangler5356]

Thank you, very informative.

[@carlosclaptrix]

Real good teaching!

[@bigmac3006]

Great vid!!

[@peterzingler6221]

Quite cool. I experienced the sucking away of air from the ground several times today. I couldn't find the thermal tho

[@dalecarpenter8828]

The ear above the ground ? Is he saying thearmal ? Good vid !!!

[@iflylilplanes]

What is the rotation of thermals in the southern hemisphere? and, are they always in the same direction?

[@wordreet]

Ooo, that's a good question. I'd like to know the answer too!

[@Len02013]

iflylilplanes found on a hang glider thread. Coriolis effect is produced by the Earth's rotation. This effect is more evident when applied to big masses of air. Hurricanes tend to spin clockwise in the southern hemisphere and counter-clockwise in the northern hemisphere. But when speaking about thermals, we are not speaking of big masses of air, we are in the micro-meteorology field. You will find thermals rotating in different directions in both hemispheres (and many times you'll not be able to notice the spin at all). Thermals direction of rotation depends on where they are generated, the ground and mountains relief , influence of air masses changes, winds, and many other factors. Coriolis could be an influence, but a weak one in my humble opinion. Which direction should we turn? Personally, I'd prefer flying against the thermal's spin (same as flying against wind). I think that in this way is easier to stay centered. Actually, we usually rotate to the side we detected the thermal and started our initial turn.

[@iflylilplanes]

That seems to be the way I thermal now, go the way you find the thermal, port wing goes up turn left, starboard wing goes up turn right. I've never noticed a change in speed which ever direction I circle in a thermal, could be the speed is not that high to be noted. Thanks for the answer.

[@dennismason3740]

I have been watching the Redtail Hawks in my neighborhood - dozens of generations of birds - for 27 years here where I live in Hollywood. Thermals were a bit abstract until Elsinore drew a spiral in the sky up and down and fore and aft... Dude - draw a spiral. Geez.

[@vlfreak]

even more inspiration to get off my butt and get another axn in the air again.. they make a half decent wedgetail-eagle chaser in summer here in aus :D