Paul Marsh Posted June 10, 2013 Share Posted June 10, 2013 Someone at the club had a new Hanger 9 Twist. First flight, bit of power from the OS 91 and the tailplane broke. All control lost and the model was destroyed as it went into trees. Rx smashed, but servos look ok. Shame, it was a nice model and flew well, although briefly. (see how much fuel in the tank). I usually brace my tailplanes, if it looks suspect... Not really acceptable for a H9 kit, although it isn't built for speed. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted June 10, 2013 Share Posted June 10, 2013 TBH Paul I think as a generalised observation I wouldn't agree that ARTF tailplanes are weak! Some are to be sure - the WOT Trainer springs to mind, but generally I have not seen a problem. I've only seen three tailplanes on ARTF's fail that I can remember - and none of them were strictly speaking design faults. One was indeed on a WOT Trainer and frankly it was just being over-flown. The pilot was a recent A pass and very full of enthusiasm! He was really throwing it around and had received several warnings from the model in terms of some quite noticable flutter. He ignored them and the inevitable happened. I don't really think you can blame the model for that - it simply was never designed to flown like that. The other two were both clean breaks caused by the builder scoring through the film too deep and into the underlying wood when removing the film to glue the tailplane in. This creates a severe stress concentration and significantly weakens the tailpplane. Sooner or later it will snap. Is this a design fault? Well if you were building the model from scratch you probably wouldn't cover the tailplane centre-section in the first place would you, so wouldn't have to cut the film away. So in a sense yes. But if the film is carefully cut with new blade using minimal pressure then generally I don't think there's a problem. So in that sense it could be called "builder error". I'm not familiar with the specific model in this case but frankly I'd be surprised if H9 got it seriously wrong in terms of the intrinsic strength of the tailplane. BEB Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted June 10, 2013 Author Share Posted June 10, 2013 Not all, but I don't think the pilot of this a/f would agree with you...This was caused by flutter, which destroyed the tailplane. One side was still attached, but the elevator was linked by a wire. If it had been a dual elevator servo setup, would've got down with one half - as long it stayed on. I've got the H9 Sundownder 90, and although it's a pylon racer, got a really weak, naff tailplane. Flown it, but was scared to push it, as would've come off. Going to brace it with c/f. Edited By Paul Marsh on 10/06/2013 10:44:28 Quote Link to comment Share on other sites More sharing options...
FlyinBrian Posted June 10, 2013 Share Posted June 10, 2013 I can not see where the tailplane broke however this looks like a lightly built 3D type model which is not designed to be flown at full power except possibly vertically upwards. I have only seen one tailplane failure on a ARF and that was on an early version of an Adrenalin, it was clear that the tailplane spar and TE had been joined in the centre (badly) The model was replaced by YT. Quote Link to comment Share on other sites More sharing options...
001 Posted June 10, 2013 Share Posted June 10, 2013 I think a bit more information needed. Was the tailplane fitting/construction one that has to have some of the covering cut away? Or as I believe, the tailplane is bolted in by the buyer? I stupidly bought a Ripmax XClaim about 8 years ago after reading a bad review. I made sure that the tailplane was firmly fixed, but the rear fuselage was composed of a series of balsa and plywood parts which had BIG gaps instead of joints, held together with air. It soon broke up, on a very soft landing, immediately behind the wing area and when the covering was stripped off, all the bad 'joints' could be seen. There were other faults too. I photographed the internals of plane and got my money back from Ripmax. (They said that their design had been changed in China where it was built.) Its stablemate the XPression was known for having a weak tailplane so I made sure that this was OK. Unfortunately the only way often to really test a built up ARTF is to pull and twist almost to destruction and that is not acceptable. You would think that the importers would do that for you, but I'll bet it very rarely happens. You would expect better from Hangar 9. Edited By Chris P. Bacon on 10/06/2013 10:54:09 Quote Link to comment Share on other sites More sharing options...
Bearair Posted June 10, 2013 Share Posted June 10, 2013 I agree with BEB, most ARFTs dont have intrinsically weak tailplanes, although the YT Rush springs to mindas one that does! If however I was using a engine more powerful than that recomended by the manufacturer I would add some bracing to the tail. Looks like the elevator has gone on your mates plane or is that just the photo not showing it? Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted June 10, 2013 Author Share Posted June 10, 2013 I had/have a Weston Hype 3D and the tailplane broke off on take-off. Was made out of soft balsa and weak. Luckily down to pilot's skill - me, I used the flapperons to keep the nose up, and got down on the next circuit. Weston UK replaced it and flown it loads of times, but never at full power, unless vertical. I've seen someone chuck this plane about and not fell to bits. The tailplane was still attached, but snapped halfway along, causing loss of elevator. Wasn't like the hype, where it snapped at the fuselage. Edited By Paul Marsh on 10/06/2013 10:59:33 Quote Link to comment Share on other sites More sharing options...
001 Posted June 10, 2013 Share Posted June 10, 2013 I have just looked at the (American) instruction manual for the Twist. Lots of disclaimers for the company for the responsibility of the pilot to fly sensibly etc. But no comment that it should not be flown fast. Edited By Chris P. Bacon on 10/06/2013 11:21:16 Quote Link to comment Share on other sites More sharing options...
John Olsen 1 Posted June 10, 2013 Share Posted June 10, 2013 BEB, you talked about cutting the covering away to allow glueing...it is better to use a fine tipped soldering iron to "cut" the covering as this will not score the underlying balsa at all. It was disconcerting to find that they told you to cut away the covering on the Hangar 9 Fokker DVII where there was actually no balsa underneath at all. Tailplanes are a problem structurally because if you make them too strong they will be too heavy and you will need a lot of lead up the front to balance it. I had an interesting example of this...I replaced my Hanger 9 60 size stick with a 40 sized Great Planes one and used the same electric plant in both. (Both were designed for IC but nevermind...) Now the H9 one had a solid sheet tailplane and fine...the GP one is built up. The H9 one had needed the 4S 4200 battery forward against the firewall, plus some lead to balance. The somewhat smaller GP one needs the battery just peeking out from under the forward edge of the wing and no lead. Needless to say, the performance, which was pretty good in the H9 one, is outstanding in the lighter GP one. It goes vertical with great enthusiasm, oops we are not supposed to go over 400 feet at our site. John Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted June 10, 2013 Share Posted June 10, 2013 Posted by John Olsen 1 on 10/06/2013 11:37:09: BEB, you talked about cutting the covering away to allow glueing...it is better to use a fine tipped soldering iron to "cut" the covering as this will not score the underlying balsa at all. Yes quite right John. Though I must admit to cutting mine and having no problems in that department,....so far! BEB PS Now seriously tempting fate! Quote Link to comment Share on other sites More sharing options...
Alan Wood Posted June 10, 2013 Share Posted June 10, 2013 I suspect that twist was just overstressed, funfly models aren't designed to be flown at anything above half throttle in level flight, full power should only be used when necessary like hovering. Another reason I would suspect it was overstressed is thats a .90 2-stroke in a .60 size model! Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted June 10, 2013 Share Posted June 10, 2013 Having suffered a wing failure this weekend that I put down to aileron flutter I do think we seriously underestimate the forces involved with our aeroplanesas the speeds build up..... I got the model down in more or less one piece but the only thing holding the wing together was the top veneer & the flap......the flutter ripped the teeth off the servo gears too...... Quote Link to comment Share on other sites More sharing options...
001 Posted June 10, 2013 Share Posted June 10, 2013 Just realised, that is a two stroke. Thought that we were talking 0.90 Four Stroke. No comeback from H9 then! Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted June 10, 2013 Author Share Posted June 10, 2013 He was at half to 3/4 power when it broke. Yes, a bit over-powered, but still. Quote Link to comment Share on other sites More sharing options...
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