TonyS Posted January 7, 2010 Author Share Posted January 7, 2010 And building up slowly..... Quote Link to comment Share on other sites More sharing options...
David E Posted January 7, 2010 Share Posted January 7, 2010 Is this any use? Sorry if that's depriving you of excuses! Have you got an really good pilots you could get to maiden it for you, and get it all trimmed up nicely? At least someone else to double check everything is working right before maiden... Quote Link to comment Share on other sites More sharing options...
TonyS Posted January 8, 2010 Author Share Posted January 8, 2010 Now I'm impressed David. Nice one. Thanks. Looks a bit different from my attempts (but I may be able to remedy this) I'll find someone to buddy up for the maiden - get me airborne then let me have a pootle around. The main thing for me with this is the relatively high wing loading compared with anything I've flown before - it'll be fast although, I hope, nice and predictable at the same time. Looks like tonight will be remaking the instrument panel though.... Quote Link to comment Share on other sites More sharing options...
Klippy Posted January 8, 2010 Share Posted January 8, 2010 Looking good Tony Quote Link to comment Share on other sites More sharing options...
TonyS Posted January 8, 2010 Author Share Posted January 8, 2010 Well they say necessity is the mother of invention...... Looking at David's piccy above I figured that the edge of the cockpit needed a white padding strip. This I figured would be easily made using the insulation off a white electrical cable of the right thickness. After much searching I found just what I needed in the form of my wifes iPod sync cable. Clearly I wouldn't be able to use this but I discovered that it had been cut into two pieces thereby rendering it available for other uses.... The pliers were already on the bench.....honest....... Anyway this fortunate find meant I could trim the cockpit... Then I re-made the panel mount... which is basically a 1.5mm balsa base plus some black cartridge paper stuck on. A panel with the dials was then cut and formed from 2mm depron. Finding something to curt these out smoothly was a bit of an issue so I used wood drill bits (with the sharp pointy spike in the centre) then I used the conical top off the cyano to round the holes out... Now please don't tell me that the layout is wrong... I know but to get all the dials in the holes had to be too small. From a scale perspective the dials would have been the equivalent of 5cm diameter. Now Boris may have excellent vision but that's a lot to ask. I think that my cockpit opening is too narrow but I'm not opening that proverbial can of wiggly things so he'll have to learn to fly the old way - by looking out of the window... Quote Link to comment Share on other sites More sharing options...
TonyS Posted January 8, 2010 Author Share Posted January 8, 2010 Now the plan was to paint the white marks and needles etc on the black paper (in the right place) then stick some clear plastic over them then glue the instrument cut outs over it all. I wanted to paint the instrument panel grey but as I'd made it from depron I only had silver in foam-safe paint so (and at this point I really did think 'stuff it) silver it is'. A lovely metallic silver - should give him a great migraine in the sunshine! Quote Link to comment Share on other sites More sharing options...
TonyS Posted January 8, 2010 Author Share Posted January 8, 2010 And voila.... Now it would have worked better if I'd used balsa for the cut-out panel (the recesses are too deep) but when I tried to cut the holes from balsa the thing kept disintegrating on me so... And painting the marks on is very difficult. If I'd had a graphics package on my machine I'd have done some on the computer and reduced them in size etc but again.... Quote Link to comment Share on other sites More sharing options...
Klippy Posted January 9, 2010 Share Posted January 9, 2010 Don't apologise Tony, it's looking great! Quote Link to comment Share on other sites More sharing options...
TonyS Posted April 10, 2010 Author Share Posted April 10, 2010 Well chaps. Today saw the maiden. Not a great success. I rigged up a dolly and used a bungee - never used one before and nor had anyone else in the club. I left the piloting to those in the club much more proficient than me . It basically turned vertical but without the power to climb out nor with the control. The chap piloting it suggests that there didn't appear to be any control as a result of inadequate air-flow over the control surfaces.... There were two attempts and both with an identical out come. The damage is incredibly light considering how heavily it went in. The major damage was caused by the battery (which is a pretty chunky beast) smashing through the base of the battery bay and then through the intake tube. Back to the drawing board.... Quote Link to comment Share on other sites More sharing options...
Dusty Posted April 10, 2010 Share Posted April 10, 2010 Tony OMG.. What a shame... 2 nice looking birds down in one day! Looks like there was not enough tension or the bungee/model/dolley got caught up in something? Might be fan, intake, ducting related problem? Quote Link to comment Share on other sites More sharing options...
Dusty Posted April 10, 2010 Share Posted April 10, 2010 Or a high speed stall? Too much elevator, model should come off the bungee and sit in "ground effect" till it builds up speed! My 2p... Ton will be your man! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 10, 2010 Share Posted April 10, 2010 So sorry to see that Tony - after all that lovely work you did too. Glad to hear that the damage is not too bad though - you MUST get it repaired and flying.Now, what went wrong? Well of course its always easy to be an armchair critic but that definitely leapt up far too steeply and stalled IMO. One thing you cant do with most EDFs is haul her up too soon, as there is no airflow over the control surfaces, and also, if the stall speed is quite high due to power/thrust to weight ratios, then it MUST be allowed to build up a good turn of speed before trying to climb. Even then, any climb out should be shallow and gentle - unless you are dealing with a super light mega power to weight ratio beast. You know the old saying that if it looks right it will fly right....well that model looks right - ..............however the take off looked distinctly wrong.Sorry if I missed it, but have you actually measured the power to weight, or static thrust?If you have, and it seemed to be good, then my assessment is a "simple" stall - the model reached an alarmingly high AOA almost immediately, ( freeze frame at 18 seconds and you will see what I mean) - and IMO, didn't have a chance to get on the step as it were.Edited By Timbo - Administrator on 10/04/2010 22:04:28 Quote Link to comment Share on other sites More sharing options...
Dusty Posted April 10, 2010 Share Posted April 10, 2010 Timbo, cant be "armchair critic"? "investigation" rather! Thats really odd! I have never seen that happen before! looking back at the video a few times now Timbo is correct! looks like your mate yanked the elevator which stalled the model! Maybe he paniced when the model was released! The RBC models probably need to be flown more than the "toyish" foam edf things knocking about! Quote Link to comment Share on other sites More sharing options...
TonyS Posted April 10, 2010 Author Share Posted April 10, 2010 Timbo, Never feel worried about offering me advice - I know that I'm a complete beginner when it comes to RC planes. I thought the same as both of you - seemed the obvious explanation but the guy flying it was until recently a BA pilot and I think if he'd made a habit of yanking hard on the elevator too early then we'd have all heard about it. Funny thing is that the second try resulted in EXACTLY the same thing happening. Unfortunately as the plane started from a slightly higher place the landing created more damage... I've never measured the thrust - havent really rigged anything up to do it. I was working off the published data for the fan / motor combo which should have given me around 1.1:1 to 1.2:1 thrust to weight. (It got a little heavy due to the glassing and the battery.) Quote Link to comment Share on other sites More sharing options...
Tom Foreman Posted April 10, 2010 Share Posted April 10, 2010 To be honest Tony, when I Bungee launch my EDF's I release first and then hit the power 2nd, elevator 3rd. With hand launches they usually sink fast and either get away with no elevator or they land nice and flat, although I would re-check that CoG, the hand launch wasn't very smooth, always throw slightly downwards, you should practice on a slope soarer I assume you had no headwind, that doesn't help either. Tom Edited By Tom Foreman on 10/04/2010 23:59:42 Quote Link to comment Share on other sites More sharing options...
TonyS Posted April 11, 2010 Author Share Posted April 11, 2010 Hi Tom, No headwind and it wasn't me doing any of the launching / flying. Thanks for the tip though. Next time I'll give it a go myself. I can see what you mean though about launching slightly downwards....It did look as though it was in a near vertical attitude even as it left his hand which wouldn't work... Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 11, 2010 Share Posted April 11, 2010 Coincidentally 18 seconds freeze frame is again the exact point that needs to be examined. True the launcher did have her slightly nose up at launch but not alarmingly so, and he did have a reasonable throw. The model immediately pointed vertically, and from that point on the pilot had no chance.My advice would be to get the COG forward - maybe a cm from the current position, and stick to a bungee launch, with gentle ramp, when there is decent headwind to help her get airborne. The bungee launch will always be easier to analyze, and as you have discovered, the damage will likely be less if it all goes pete tong as soon as she lifts off. Keep at it mate, youve invested too much of everything into this model to not get her airborne.Incidentally, I never suggested that your pilot hauled too much elevator, just that it was a stall due to high AOA at too low a speed, and this could be due to the bungee attachment point being too far behind the sweet spot. I hate bungees, and these days simply wont build or fly any model that requires them, so am no expert, but if the hook is too far rearward, this will upset the AOA on release. Quote Link to comment Share on other sites More sharing options...
Ton van Munsteren Posted April 11, 2010 Share Posted April 11, 2010 Tony, Sorry to see that the maiden went wrong. The problem you have is that the cog is far to much aft. It must be far more forward and can even be a little more as per plan for a first start wit handlaunch because that is more critical. With the power comming from underneath the wing and no airflow over the controles and the cog to far aft, you will never stand a chance correcting it with a flip as a result. As can be seen on the first vdo a line start gives more start speed so you win 5 mtr before you flip but again no chance at all. Make sure that the cog is on the spot or a litthe more forward and with the handlaunch on 3/4 it will flyaway like a trainer. Can you tell wher the cog is now on the model. Please please please do not temp to fly the YAK23 with a aft cog this will never work and you will end up crashing your model. Quote Link to comment Share on other sites More sharing options...
David E Posted April 11, 2010 Share Posted April 11, 2010 Tony, Sorry to hear you're having such a nightmare with it Glad to hear the damage isn't too severe, though. To my inexperienced eye, the angle of attack looked wrong on the dolly launch as soon as it was released. Is it possible that it's pushing on a point too far back or too low on the aircraft? The same went for the hand throw, I think pushing on the exhaust outlet may not have helped. As everyone else has said, the C of G needs checking. Good luck with the repairs, I hope they prove quick and easy. Definitely worth persisting with it though, I'm sure it'll be worth it in the end. It's sure to look great in the air. Quote Link to comment Share on other sites More sharing options...
TonyS Posted April 11, 2010 Author Share Posted April 11, 2010 Just spent ages posting a reply with pics etc and the blinking site kicked me out again!!!!! Oh well, let's try again. Ton / David, Thanks for the advice and comments. I finally plucked up the courage to open up the model today to inspect the damage and I'm amazed at how little there is considering it came down quite hard...twice. Had it not been for the weight and momentum of the battery I don't think there would have been anything more serious than a horizontal stabiliser coming unstuck! It has to be said the glassing with Skin-crylic is very tough. I also like it as it doesn't stink like two part resin. Anyway a couple of pics of the damage.... I'd just started to cut away the paper intake tube before I decided to take the next two pics.... I have a large enough piece of the black cartridge paper left over from making the tube for the Gloster and this will be inserted and taped into place.. Quote Link to comment Share on other sites More sharing options...
TonyS Posted April 11, 2010 Author Share Posted April 11, 2010 Cont.... (didn't want to risk losing the post again.....) This time I'm going to "beef up" the battery bay by making it from ply. This will help to add a little weight at the front too and move the CoG forward. Just to add... Having read Flanker's brilliant thread "Ow splat, you won't fix that" the damage to mine seems cosmetic. I don't have Flanker's expertise but I'll dig deep find something that'll get me through this repair. I do have one slight problem though. I tried to remember to pick up all the bits but I'm missing a fairly key piece. I need to make a former to go around the circumference of the tube between the base of the battery bay and the tube. I don't have a template for the original former or a scale plan. Any ideas...?Edited By TonyS on 11/04/2010 17:35:56 Quote Link to comment Share on other sites More sharing options...
Kelly Posted April 11, 2010 Share Posted April 11, 2010 Ouch , I know the feeling Hand launching issues with my Me 109,still a bit hairy in nil wind conditions. Great looking model Tony Quote Link to comment Share on other sites More sharing options...
TonyS Posted April 11, 2010 Author Share Posted April 11, 2010 OK. I just worked it out. Find a piece of balsa that is about the same length as the diameter of the remaining former keep trimming it until I have the right diameter then I can make my own piece from that - too obvious really.. Quote Link to comment Share on other sites More sharing options...
TonyS Posted May 22, 2010 Author Share Posted May 22, 2010 Hi Chaps, Well, I repaired the plane and took it back to the club to fly today. Light breeze only. Sadly, same result as last time. I'd shifted the battery well forward and added in another 60g of lead up front, triple checked the CG and following a superb bungee launch the plane nosed up and even on full down elevator wouldn't change from that attitude. Throttled off and it nose-dived into the ground from around 20 feet. Typically, the LiPo buried itself destroying the intake tube (again) and this time the nose took a pounding. It's a pity I didn't have my camera but it looked pretty similar to the last posted video to be honest. Lots of theories at the club. 1 The exhaust tube from the motor is vectoring thrust down relative to the fuse - this may be pushing the nose up. 2 The motor may be too powerful and a launch at half throttle until speed has built up and the control surfaces can 'do their stuff' may be appropriate. 3 The control surfaces are too small. I'd discount the latter having seen Ton's fly. I think that the Wild Beast in combo with the slight downward vector on the thrust tube is forcing it to nose up. A fairly big re-build is called for..... Quote Link to comment Share on other sites More sharing options...
David E Posted May 22, 2010 Share Posted May 22, 2010 Bummer sorry to hear that. I don't have anything to in on, obviously, but other things worth checking/considering for the next attempt might be: -Are all control surfaces moving the right way? -Is the catapault causing the rotation by applying force behind or too far below C of G? -Is the tail incidence ok? How about trying a throttle off catapault launch with glide straight to land? Might help narrow down cause? Quote Link to comment Share on other sites More sharing options...
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