19th April was when I finally got out to try a maiden on this plane - sorry no video! I didn't fancy juggling a video camera and flying the plane. Well, my 'Tribewt' – newly named - just floated off the ground in what looked like a perfect balanced take-off. But no! It was tail heavy - and things soon went wrong. A drooping tail and excessive control throws on the ailerons soon had me beat. After a few wobbles and swoops I nosedived and pranged the propeller. The plane survived relatively unscathed as the foam nose absorbed a fair bit of the shock. Well I should have stopped there, but I put on another prop, adjusted the elevator trim to try and compensate for the heavy tail and took-off again. Well, it flew, sort-of, but (!!! because I didn’t take time to check properly !!!) the last crash had loosened the elevator horn. Soon it had worked loose and I was struggling to get any reaction from the elevator. The plane climbed to a dead stop, did a back flip and plunged straight down for another dirt nap. I wiped out the front end, but the motor and pod survived! I did a field repair, hence the packing tape on the nose, but I couldn't repair the control horn - which was probably just as well - who knows what the next crash would have wrecked!
When I got home I rebuilt the nose, losing some of the fancy detail,
and took the opportunity to shift the wing back about 15mm.
I also fixed and reinforced the control horn,
I know it looks a bit askew but it's screwed through into the lolipop stick underneath so its solid.
Second outing was Sunday 2nd June. You’ll see from the film that it flew pretty well, though I felt it was still a tiny bit tail heavy.
First flight ended in some kind of brown-out, and the plane did a nasty belly flop. Fortunately nothing was broken. I swapped-in another battery and this time I hand launched. Once it was trimmed-out it was great fun.I was quite happy just looping it around the field. The landing was a bit rough again, but I reckoned with better balance it would come down a lot easier.
I flew it one more time, sorry no video, but stuck on another battery just as an additional balance weight. What a difference! The plane just cruised around - I was stunned how smooth it was. I even tried a bit of inverted flying, but I was on low rates and couldn't keep the nose up. A quick roll got me out of trouble.
I had a battery monitor on the battery and after about ten minutes of very satisfying flying the bleeper went off. As I coasted in for the landing, I had another brown-out/signal failure which lost me the elevator at the last part of the approach. The landing was bumpy but OK, but I think I’ll try another receiver.
So I added more weight, prettied it up, and put in another receiver. What a difference!
Overall I’m very pleased with this plane.My final CG is about 20-22% of the wing chord. If you look at my other recent build which I'll post soon – the Velie Monocoupe, you’ll see I'm having similar problems with finding the CG. Initially I was looking at somewhere between 25-30% of the chord – but again it was tail heavy. I’m concluding that for the Armin wings I’m building I should start with a CG more around the 20% of chord and work from there.
I was thinking about this monoplane fuselage layout and reckon it could be easily adapted to a number of turtledeck variations; cockpit well to the rear, single cockpit, enclosed cockpit, etc.
The only issue is the access for the servos. A servo hatch would be easy enough. I found that if I stripped the paper from one side of the foamboard it could be coaxed into forming quite a tight curve, with the paper on the outside.
Some more images after repainting.