Posted by TTRotary |
Oct 22, 2012 @ 07:45 PM | 4,548 Views
I crashed my World Models .60 Spitfire on turn to base yesterday, on the 3rd flight. The plane went in inverted, almost straight in. It happened very fast and was over before I could react. I held up elevator all the way down. Total loss. So what happened?
Prelude to disaster: I completed a windward pass down the runway after coming out of an immelman. The plane was about 200 feet up or so, lower than normal perhaps. Downrange, I pulled the throttle back to 1/2 and dropped the gear, so I could see clearly that both legs were down. I then initiated a turn to downwind leg, with the plane still moving along pretty fast. Flaps down. Plane starts to lose altitude. Midway down the downwind leg, I added elevator to gain altitude. Inexplicably, probably because I was in the mindset of scrubbing off speed, I did not advance the throttle. This was probably brain fart #1. The plane did gain altitude, however, but was still lower than it normally would be. I remeber thinking that I could not see it well (see below) At this point, I initiated the turn to base, using ailerons only. I have no idea how much up elevator I was still holding at this point. And then it happened. Loss of orientation, some stick movements of some sort, then in it went. I probably tip-stalled it in the turn, so that it rolled over to the inside of the turn - or maybe it was not headed in the direction I thought and my stick input was the reverse of what it should have been.
1. The 360 degree vector thrust system needed lots of adjustment to get right. All 4 push rods had to be dremelled down a bit.
2. Two servos had to get the arms re-attached on the next spline. This was painful on the wing aileron servo, but I managed it with minimal damage by running a string under it and pulling up gently with some gentle warming from a heat gun. This was necessary to get the geometry squared up after the radio had centered the servos.
3. The Rudder input to the Vector Thrust system comes off a Y-harness from Rudder output from the receiver. Using Sub Trim, I centered the "Vector 3" servo, then centered the nose wheel steering mechanically. Fortunately, they are going in the correct directions!
4. The instructions for the DX7 programming in the Manual are Bass Ackwards in a couple places...
5. The "Gear" channels needs its Travel adjusted way down. Full travel causes stress on the landing gear servos. Adjusting them properly eliminated the "servo chatter" when the model is idle.
6. The Mixes going into the Vector Thrust servos need to be adjusted way down - else they want to move too far and stress the mechanicals, especially if both Elev and Aile inputs are given. Beware of over-travel!!
7. Front Landing Gear does not retract neatly all the time - sometimes it hangs a bit low and at angle. I came up with a very simple zero-mass modification to make the nose landing gear retract...Continue Reading