SkippyUK Posted October 3, 2013 Share Posted October 3, 2013 Any chance of a photo side on to the end of the main wing when on flat ground? I'm really curious about the AoA of main wing vs tail especially as it looks nearly symmetrical section. All my planes have an upward AoA when on ground and the Bipe behind looks more normal. Glad you've found a solution that works now. Skippy Quote Link to comment Share on other sites More sharing options...
crispin church Posted October 6, 2013 Author Share Posted October 6, 2013 i try and get photo done today plane behind is a high wing cub and yer its a normal as can be zebra ex yellow cub can be Quote Link to comment Share on other sites More sharing options...
crispin church Posted October 6, 2013 Author Share Posted October 6, 2013 wing to tail both level no AoA with tail at zero Quote Link to comment Share on other sites More sharing options...
SkippyUK Posted October 7, 2013 Share Posted October 7, 2013 Thanks for taking the time Crispin - can see the wing profile better now. Picture 3 still looks a bit odd to me - if the tail came up off the ground to make the red and blue lines more level with only a bit of upward slant as would be normal for take-off then it looks like you would lose all of the main wing AoA except for a bit of reflex. Do you have to put in a lot of elevator to fly upside down? Be interested to hear what BEB and the other experienced guys thought. Only similar high wing plane I have is an old Nova trainer which has flat bottomed high lift wing and it definitely has more AoA on the ground than your Tornado. Skippy Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted October 7, 2013 Share Posted October 7, 2013 It's possible that the apparent lack of AoA at the wingtips could be due to washout. It's difficult to see why the decalage angle should be different to any other example - but this isn't a "trainer" - more of a high/mid wing introduction to "pattern" model where you would expect something nearer to a "zero-zero" configuration... Quote Link to comment Share on other sites More sharing options...
crispin church Posted October 7, 2013 Author Share Posted October 7, 2013 sorry cant say about flying upside down cant remember fly upside down will try next time out would be interested to know if there was any other tornado owners out there if theres are the same looked on some reviews and no one else say its a pain to get off ground but now i can drag it off the ground it does put a smile on me face glad i stuck to it not often a plane beats me Quote Link to comment Share on other sites More sharing options...
Stevo Posted October 7, 2013 Share Posted October 7, 2013 As I said, I gave up with mine, a right pain to get off the ground, if at all. All other Blackhorse models I've had have been excellent. Would not recommend this one - at all ... Glad you have persisted more than I!!! Quote Link to comment Share on other sites More sharing options...
crispin church Posted October 8, 2013 Author Share Posted October 8, 2013 upside down needs a lot of push on the sticks about 3/4 of the full throw to level out looking at prop there up thrust so i put some down thrust in and will try that next time Quote Link to comment Share on other sites More sharing options...
SkippyUK Posted October 8, 2013 Share Posted October 8, 2013 Must be age creeping up on me - forgot all about my son's Wot 4 sitting in the shed but 'borrowing a picture from Marko - hope it's OK Marko...... WOT4 Edge on - This definitely shows the main wing and tailplane perfectly lined up, And during take-off, the AoA is very evident. IMHO the AoA is somehow incorrect but I don't know why and having to feed so much stick in when inverted sort of confirms this - don't have to put that much in on the Nova and that's a flat bottomed wing. C'mon BEB and the rest of you, you're wizards at these kinds of problems.... Skiipy p.s. all respects to picture owners. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted October 8, 2013 Share Posted October 8, 2013 Skippy I think your shot of the Wotty taking off shows why I think the tail needs to get lower so the model can take off more easily. I say the taildragger conversion has meant the tail can't go down, to increase the wings angle of attack. On the inverted performance, to me, that shows that the C/G is too far forward. Moving the C/G back (bit by bit) should reduce the amount of down ele needed. It may well help with takeoffs too. But while the tail is being held up high by the tailwheel, the elevator isn't going to be able to push the tail down. Quote Link to comment Share on other sites More sharing options...
SkippyUK Posted October 8, 2013 Share Posted October 8, 2013 Chris, just to understand the implications of bad CofG better, if the plane was very nose heavy then in normal flight, would you expect there to be a fair amount of up elevator to be dialled in to maintain level flight or could this be negated by up thrust which, as crispin said, would adversely effect inverted flight and make the situation worse? We all seem to be agreeing that the main wing needs a better AoA when on ground - a higher U/C might solve this maybe or remove the tail wheel and fit a skid? Skippy crispin, not trying to hijack your post but want to get a better handle on this stuff for when i get back into larger IC again - my small depron and epp foamies never fly the same twice due to warping in the sun etc. but they are still great fun even if they need re-trimming each week. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted October 8, 2013 Share Posted October 8, 2013 Sorry guys not been following this one - here now! Looking at that picture - well Martin could be right it could be wash-out, but,...if it is its a hell of lot of washout! This model is unlikely to have washout I would have thought - it doesn't really need it. Looking at all the evidence the best I can come up with is this: 1. The wing incidence is too negative - this is evident in the photo and if you can see it with the naked eye then it's far too negative! Also the information that it needs a hell of lot of down inverted would bear this out - I know that sounds counter intuitive but I think what is happening is that to get it to fly right way up with that amount of "down thrust" its effectively got massive up trim - which of course becomes massive down trim when we invert the model - result you need a shed full of push to keep it level. 2.This problem is compounded by Chris's point. The conversion to tailwheel is limiting the model's ability to rotate - you just can't get the back down to bring the nose up because the tailwheel is stopping it. 3. You might get away with point 2 if you had bags of power to literally drag it off the ground - but while 90W/lb is "OK" it hardly constitutes "bags of power"! So you can't even pull it off the ground. Solutions? Several possible: 1. Put a bit of packing under the leading edge - just try an 1/8th of inch or so to start - a piece of 3mm ply say. See if that improves things. 2. Lower the back end or lengthen the main legs. 3. Get more power from somewhere! BEB Quote Link to comment Share on other sites More sharing options...
crispin church Posted October 8, 2013 Author Share Posted October 8, 2013 cog dead on factory settings the webra that on there now is giving 3kg of static thrust i did put a high front wing mount holes but never tried it in end as webra was pulling it off ground will try it next time out i dont get about tail wheel when its at speed the tails comes up and lift off before it gets near the ground with up elevator Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted October 8, 2013 Share Posted October 8, 2013 Posted by crispin church on 08/10/2013 20:04:43: i dont get about tail wheel when its at speed the tails comes up and lift off before it gets near the ground with up elevator That's just the point Crispin, When the tail is sitting high as it races accross the ground, the wing is in effect pointing downwards. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted October 8, 2013 Share Posted October 8, 2013 Chris is right I believe. Its acting like the aerofoil on the back of a formula one car - it giving you down thrust - not lift! BEB Edited By Biggles' Elder Brother - Moderator on 08/10/2013 20:20:55 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted October 8, 2013 Share Posted October 8, 2013 Within the limitations of a camera lens, if you project a straight edge along the tip of the tailplane in at least 3 of the pictures the result actually appears to be a zero angle of attack. Crispin - do you have access to an incidence meter? A forward C of G will result in a well trimmed model needing a lot of down elevator and is my usual basic check on a model's C of G. Manufacturer's settings have been found to be wrong so many times, so don't take them as gospel... I agree that the root cause of your problem is most likely ground attitude and lack of power. As BEB has said many times, lift increases with airspeed at any given angle of attack - the increase in airspeed resulting from an excess of thrust over drag. With a zero-zero model there's little tendency to lift off without a positive rotation or high ground angle at lower speeds and your lack of power would probably have meant that at a low A o A and low airspeed due to wheel drag etc. insufficient lift was being produced for flight. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted October 8, 2013 Share Posted October 8, 2013 Another point is that the wing section looks pretty near symmetrical - that being the case without a definite positive incidence you'll not get any lift. BEB Quote Link to comment Share on other sites More sharing options...
crispin church Posted October 9, 2013 Author Share Posted October 9, 2013 well from this thread i have learnt so much thank you all no i dont have a incidence meter the cog calc i use most say a 124mm not 110mm cog so trying that next time out and will also try front of wing higher as well and report back Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.