Nicholas Booth Posted May 4, 2009 Share Posted May 4, 2009 Hi all I have had abreak from flying for a while but am about to ressurect my Top Flite DC3 that I crashed ealry last year. It only had 2 flights, I will try to list both flights for an idea of what happened. The kit was built from a Top Flite standard kit and converted to electric whilst doing so. The power supplied from the motors is far greater than the plane would ever need to fly. I have put 3 bladed, variable pitch props due to ground clearance. First flight: It taxis fine without issue, no ground looping an felt nice and stable, due to our field layout their was a fairly strong side wind from right to left, but nothing extreme. I accelerated fairly quickly getting her to 3/4 power at which point she pretty much jumped into the air (45-55degrees) at about 15 feet she dropped the right wing to an almost knife edge position, I managed to use full rudder (I had left lots of rudder in just in case) and brought her back to the straight and level. after which she flew ok but placed a lot of down in the elevator to keep her level. I was quite nervous when flying her but could not remember much else, except on landing I pulled up elevator and had a fairly feeble response with a stronger than wanted bounce on the floor. no damage. Second flight: Not tempting fate I didn't fly again the same day, but a few weeks later. I had put the ealrier issues down to not keeping her in the ground long enough although the speed had been really fast. This time the wind was from left to right and about the same speed. Knowing that I had since trimmed the plane, I expected a different take of and applied gentle throttle, holding up elevator until the tail rose and then tried to use down to keep her on the ground without hitting the props on thr ground. This time she took off at 1/3 throttle and there was nothing with the controls I could do to keep her on the ground. This time she dropped the same right wing, caught the ground and cartwheeled. The elevator felt a little bit twitchy. I did not use flaps on either take off, but tested them first flight, the first setting raised the nose by about 5degrees, the second about 15 degrees. I am just finishing the repairs and am looking for help in what could be the cause and maybe a fix or two If you can help then please do as I would like to fly the plane soon and right now expect it to do the same thing again unless I make changes Nick Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted May 4, 2009 Share Posted May 4, 2009 Could it be that your COG is a little rearward? I say this because you mentioned that the elevator felt a little twitchy, plus you stated that a lot of down elevator was required to fly her straight and level.Edited By Timbo - Moderator on 04/05/2009 12:23:05 Quote Link to comment Share on other sites More sharing options...
Nicholas Booth Posted May 4, 2009 Author Share Posted May 4, 2009 it did on the second flight, but you know what it is like when flying a plane for the first time, I had thought about moving the CoG forward a tad as part of the rebuild. I just wanted to make sure there was nothing else I could be missing Quote Link to comment Share on other sites More sharing options...
Stephen Grigg Posted May 4, 2009 Share Posted May 4, 2009 Could you get an expert to fly it for you they can usually tell in an instant the problem and have the expertise to get it down safely and fix any issues Quote Link to comment Share on other sites More sharing options...
Nicholas Booth Posted May 4, 2009 Author Share Posted May 4, 2009 Whilst I wouldn't class myself an expert, I have flown a large number of planes over the last 7-8 years including a few really tail heavy and some nose heavy kits. The problem is that I have never had an issue keeping the plane on the ground before, which I attempted to do the second flight. I expected the tail to lift but not for the right wing to drop both times. I am pretty sure that whilst in the right circumstance it might have been saveable the second flight, it dropped its wing so fast I couldn't catch it. What I didn't state in my first post, was that I did a stall test on the first flight to see what it would do after the bad take off but it came to an almost stop and just droppped its nose. not what I expected nor the other flyers at the field. I think that moving the CoG is a first attempt and may also remove some of the pitch on the blades to increase the speed before take off...... Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted May 4, 2009 Share Posted May 4, 2009 hello nicholas--one of my friend's spent a fortune on a DC3-built from a mag plan pack-it do'es exactly the same as your's--it's a real ********drop's a wing when comming in to land and when taking off-if you lift it too quick-same wing will drop-not gently-but really bad..it's a hand full at take off and landing..not so bad when there is a breeze to help it. a classic example of tip stalling-last time out it got damaged-i advised him to get rid-i would advise you the same unless you like a challenge.. ken anderson................. ps--last time he flew it and it t/stalled there was two round thing's fell out of his pant's leg bottom's....................... Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted May 4, 2009 Share Posted May 4, 2009 Nicholas. Another thought occured to me - have you checked for equal thrust from both motors - it does now sound rather like it yawed itself into the ground. I presume that you have checked the more obvious possibilities like an off trim rudder, and warped wing etc. Quote Link to comment Share on other sites More sharing options...
Nicholas Booth Posted May 4, 2009 Author Share Posted May 4, 2009 I know I checked the wing both before and after the crash so don't expect the wing to have any issues. as for the motors, I couldn't get a positive read on the rpm's so used the rough speed which seemed to show within 150rpm of each other and also their voltage pull was less than 0.1 of an amp, but thinking now there may still be a difference in actual pull of the motor which will be worth checking. I will create some sort of harness to check each motors actual pull. Hopefully I will get some freetime this week to start checking the bits out. I went to spray the nose back up to green today but found I had not sealed my air canister properly.......off to the shops again tomorrow. Quote Link to comment Share on other sites More sharing options...
DAVID CLIFFORD Posted May 4, 2009 Share Posted May 4, 2009 What about thrust angle? would that have a bearing? Quote Link to comment Share on other sites More sharing options...
Nicholas Booth Posted May 4, 2009 Author Share Posted May 4, 2009 Trust angles were a long story. When build the kit it called for 6.5Degrees down thrust and 4 degree outward thrust for each motor. I had a long email exchange with Top Flite re the angles and they stated that the down thrust was required, but the side thrust was there to stabilize the plane in case of a motor loss. As it was built electric, and the chances of a normal styl engine out were not there, I removed the side thrust (had seen it done on other forums and flown without issues). Again, not sure what to expect with the side thrust and what 4degrees outward on each motor may give. Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted May 5, 2009 Share Posted May 5, 2009 http://www.bvrmc.co.uk/ hello nicholas-check out our web page/video's--forgot to mention that the DC3 video is on here-you'll see the wing drop on take off and attempt to drop on landing......... ken anderson........... Quote Link to comment Share on other sites More sharing options...
Nicholas Booth Posted May 5, 2009 Author Share Posted May 5, 2009 Hi Ken Thanks for the video, I wish I had mine on film as I think I would have seen a lot more information. In your flight you can see the right wing lift off before the left and would have point me more towards the thrust angles. Did he use any flaps do you know. I will check my angles out as a matter of priority first I think. Nick Quote Link to comment Share on other sites More sharing options...
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