Levanter Posted November 8, 2020 Share Posted November 8, 2020 I have had a part built Sophisticated Lady on the shelf for some time and this week I decided to finish it off. Not having tried film hinges before I thought I would have a go using this method for the elevator. Many many years ago I built a Caprice and that has a de-thermaliser tailplane to put it into a descending mush when the fuse burns through. Following this theme I wondered whether the elevator alone would have enough authority on its own to put the Sophisticated Lady into a mush. The reason for asking is that with the film hinge I will have limited travel in one direction and say up to 90 degrees travel in the other. Should I therefore arrange to have as much up-elevator as possible and more limited down? Or maybe it's not going to work anyway so it doesn't matter. Levanter Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted November 8, 2020 Share Posted November 8, 2020 Personally I would say that the elevator would not have the authority to put the model into that complelety stalled attitude that a dethermaliser does. But it is an awfully long time since I did any serious free flight flying. A Calypso Major at the RAF Champs in the late 50s 1 Quote Link to comment Share on other sites More sharing options...
MattyB Posted November 8, 2020 Share Posted November 8, 2020 I agree - without significantly increasing the horizontal tail and elevator area I doubt this will be effective. A better way to escape from big air with RE aircraft is a spin or (if it won’t spin) flying inverted (which with the wing section on that will be super inefficient, exactly what you want!). Edited By MattyB on 08/11/2020 09:35:37 Quote Link to comment Share on other sites More sharing options...
Levanter Posted November 8, 2020 Author Share Posted November 8, 2020 Thanks Peter and MattyB I'll just go with the advised travel on the plan. Just one more question. How do you get inverted? Off the top of a loop or bottom of a bunt? I image it will be seriously unstable. Levanter Quote Link to comment Share on other sites More sharing options...
MattyB Posted November 8, 2020 Share Posted November 8, 2020 Off the top of a loop - bunting a model like this poses too much risk of reaching disintegration speed! It will be very unstable, but remember you are just trying to escape from a big thermal - the best way to do that is to fly inefficiently in a straight line, you shouldn’t need to turn. It’s worth practising at a low enough altitude you can see what is going on in a non-crisis situation, that way you will know what to expect if you are doing it at specked out range! Quote Link to comment Share on other sites More sharing options...
Levanter Posted November 8, 2020 Author Share Posted November 8, 2020 Thanks MattyB Perfect Levanter Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted November 8, 2020 Share Posted November 8, 2020 Could you add spoilers into the wing, that would make dumping lift much more controllable. Quote Link to comment Share on other sites More sharing options...
Levanter Posted November 8, 2020 Author Share Posted November 8, 2020 I have a 2m Sonata converted to electric (again half finished) that has spoilers so it will be interesting to compare the two. One day that is! Levanter. Quote Link to comment Share on other sites More sharing options...
Levanter Posted November 8, 2020 Author Share Posted November 8, 2020 I have a 2m Sonata converted to electric (again half finished) that has spoilers so it will be interesting to compare the two. One day that is! Levanter. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted November 8, 2020 Share Posted November 8, 2020 Once you've used spoilers then you'll probably miss them on models that don't have them. Years ago I had a 2 channel Multiplex Alpha H, got into a huge thermal off the slope, decided the best way out was to loop down, was great for the first 3-4 loops and then the wing snapped off, that stopped it from going up............................ Quote Link to comment Share on other sites More sharing options...
MattyB Posted November 9, 2020 Share Posted November 9, 2020 Posted by Frank Skilbeck on 08/11/2020 13:41:03: Could you add spoilers into the wing, that would make dumping lift much more controllable. Retrofitting spoilers is generally a complete pain - I tried once in an old bring and buy RE job, but quickly decided it would be harder than building a new wing and flew it as it was! Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted November 9, 2020 Share Posted November 9, 2020 One of the old dethermalisers used was a parachute attached to the tail. That would work. You could even arrange a second operation to release the line once the model was down to a safe height. Quote Link to comment Share on other sites More sharing options...
Matt Carlton Posted December 15, 2020 Share Posted December 15, 2020 Perhaps some thin ply plates let into the fuselage sides using a servo to 'pull' them open against a band, somewhat like the fuselage air brakes on many jet aircraft. Going further with the parachute idea, if it were mounted in a streamlined fairing on top of the wing, it could be located at the CG to permit a vertical descent? Given the band on wing, it need not be a permanent fixture. Just a thought. 1 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted December 16, 2020 Share Posted December 16, 2020 I've used large simultaneous upward deflections mixed in with ailerons on several gliders (around 45 degrees), which have been very effective - even on a 4m Discus. Easy to program on most transmitters these days assuming you have separate aileron channels/servos. Aileron control has still been effective enough especially if they are deployed once established on an approach. Edited By Martin Harris on 16/12/2020 00:44:57 Quote Link to comment Share on other sites More sharing options...
Slope445 Posted May 30, 2021 Share Posted May 30, 2021 (edited) I’ve used the tipped up (like 70 degrees) aileron method on my 100 in. Ventus. An added on, contoured, thin piece of fiberglass installed on the top of a 2 meter Phoenix and a tipped up central flap method on a 100 in. Trendy. All worked well to dump altitude. Edited May 30, 2021 by Slope445 Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted May 30, 2021 Share Posted May 30, 2021 (edited) On 15/12/2020 at 21:40, Matt Carlton said: Perhaps some thin ply plates let into the fuselage sides using a servo to 'pull' them open against a band, somewhat like the fuselage air brakes on many jet aircraft. Going further with the parachute idea, if it were mounted in a streamlined fairing on top of the wing, it could be located at the CG to permit a vertical descent? Given the band on wing, it need not be a permanent fixture. Just a thought. I like that idea, in fact I did consider doing it on my PSS A4 Skyhawk (speed brakes) but I thought it probably had enough built in drag as it was and didn’t need them! I don’t even think they need to be ‘let in to the fuselage sides’, just a couple of hinged pieces of 1mm ply operated by a single servo would not cause very much drag when closed and be highly effective when open. May not cause too much of a trim change either. Edited May 30, 2021 by Piers Bowlan Quote Link to comment Share on other sites More sharing options...
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