Olly Giles Posted July 21, 2011 Share Posted July 21, 2011 I have recently been given a Thunder Tigre eHawk 2m span glider and i have been trying to thermal it effectivly. Trouble is the only gliding experience i have is of full size gliding. I have read a few things about using flaps etc to gain more lift? Any tips and adive would be fantastic. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 22, 2011 Share Posted July 22, 2011 None of the experienced model glider guiders seem to have taken any interest in this Olly so I'll add my three ha'pence... In full size, thermalling flap is handy to get a smaller turn radius (as you can reduce airspeed by a couple of knots) and therefore get into the core of a thermal and also when dolphining will give a few more feet in the pull-up but unless you're flying a very large scale glider I'd doubt that they would make very much difference. Negative flap is used between thermals to optimise the wing section for high speed flight and the theory explained to me was that the fuselage provides lower drag by effectively changing the angle of attack of the wing while maintaining the same fuselage angle. I'll reserve judgement on that in hindsight but I also have a theory that providing reflex to the trailing edge lessens the download provided by the tail therefore reducing induced drag. As I recall,, my ASW20 didn't require any retrimming with flap changes but simply settled into a faster airspeed. My limited model experience is leading me to conclude that it's not at all easy to find organised thermal lift low down and I've had more success (with a 2M block of foam resembling an ASW28) slowing down and flying straight through lift than in maintaining any prolonged themal turns. This may simply be ineptitude but as model thermal soarers are rare within my club I don't have much to compare with. I'd guess, as with most things in this hobby, there's no substitute for practice! Edited By Martin Harris on 22/07/2011 13:51:19 Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted July 22, 2011 Share Posted July 22, 2011 olly - i would have thought if you have experience of full size gliding-you would be telling us how to do it.....when i have been at our flat field with a model with a motor on the front...i normallly head over a bunch of tree's we have...and have got in to lift(thermal) off them......and up the model go's......i also watch for the bird activity and follow them in to a thermal.......the more experienced lads i fly with up the hills(HTP).....will often say that there is a thermal comming through.....to me - they might as well speak chinese...so i just agree with them.... ken anderson ne..1 thermal dept.... Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 22, 2011 Share Posted July 22, 2011 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 22, 2011 Share Posted July 22, 2011 I've found trees tend to create turbulence rather than proper themals.That's not to say that the turbulence won't nudge some warmed air upwards but the lift seems to be very bitty from our local woods. You do seem to get some late thermals from woods as the trapped air cools slower I'd guess? If you feel a cool breeze - especially with a change of wind direction, it's often the sign of a thermal going off - it's the surrounding air being pulled in to replace the bubble of warmer air that's just detached itself from the ground. This is what your psychic mates are probably going by, Ken... I think birds are the most reliable indicator (other than dust devils but they're rare in this country) and our local red kites and buzzarrds are extremely handy thermal markers!Edited By Martin Harris on 22/07/2011 17:51:25 Quote Link to comment Share on other sites More sharing options...
Gaz Elliott Posted July 22, 2011 Share Posted July 22, 2011 We have a lake/ large water area which is good for lift. Unsure if the water content of it has anything to do with it but poss the water vapourising ??!! Quote Link to comment Share on other sites More sharing options...
Gaz Elliott Posted July 22, 2011 Share Posted July 22, 2011 We have a lake/ large water area which is good for lift. Unsure if the water content of it has anything to do with it but poss the water vapourising ??!! Quote Link to comment Share on other sites More sharing options...
Erfolg Posted July 22, 2011 Share Posted July 22, 2011 Olly to thermal, you need to find one. In principle it is obvious, when the model goes up, you are in a thermal. In practice, it is often different to the ideal. Have the model set to glide straight, observing all the time. If the model veers to the left, there could be a thermal to the right. Some will allow the model to continue round, cross their previous path, and look for signs of bobbing up slightly. If you think you are in a thermal, circle gently, minimise inputs, keep the model flat. After a bit of practice and flying the same model, so that you know it very, very, well, you can also tell from its speed, if it is sinking or rising, if it is being pushed out of a thermal, or passed through one (nose rises slightly). At the end of the day, it is knowing your model that is more important than the model itself and of course, experience and interpreting what you see, or think you see. All the other things from what birds are doing (seagulls, buzzards and swallow types) give many clues. Also getting under a cumulus type cloud, crossing a dark field, etc can help. You will often know a thermal has gone, by a sudden gentle wind as it draws in cooler air. Books have been written on what to do, yet it is really experience and practice that matters. It is a lot easier with electric glider models, yet the bungee, told you how well you really were doing. Quote Link to comment Share on other sites More sharing options...
Conwy Soarer Posted July 22, 2011 Share Posted July 22, 2011 good bit about thermal soaring here: http://www.torreypinesgulls.org/rcsoar.htm This is on ebay at the moment - its an old book but excellent still, I still have a very well used copy: http://www.ebay.co.uk/itm/RADIO-CONTROL-THERMAL-SOARING-MODEL-GLIDER-R-C-M-/270783293262?pt=UK_ToysGames_RadioControlled_JN&hash=item3f0bf1274e#ht_500wt_1156 Quote Link to comment Share on other sites More sharing options...
Olly Giles Posted July 22, 2011 Author Share Posted July 22, 2011 Thanks guys. I had a bit of thermalling today over the woods at the far end of our field. It had just rained and the sun came out which formed some small cumulous clouds down wind of the woods which indicated rising air. after climbing to a decent height i stayed roughly where i thought the lift would be. It wasnt much but it was enough lift to reduce my sink rate to virtually 0. I even had it climbing for a little while. I experimented and found that turning lost me height even in the very shallowest of turns. I found that a tiny bit of flaps helped me stay in the lift. I defiately need more practice though. Quote Link to comment Share on other sites More sharing options...
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