C of G or thrust line

[John Keywood]

I have just landed my Wot 4 badly on its maiden flight. I have converted it to electric using the information from Chris Foss. When it flew, it wanted to dive whenever I gave it more revs. I had to use a lot of up elevator trim to get it to almost fly level. It did take the undercarriage off when I landed it heavily.When I did the autopsy, I used a commercial C of G balancer instead of my fingers. It was very nose heavy.

Now that it is repaired and before I test fly it again, can any one tell me if it could have been the fact that it was nose heavy or is it likely that it had to much down thrust?

Thanks,

John

[PatMc]

If the nose down pitch increased with power then it's too much downthrust.

[Lindsay Todd]

Hi John, sounds like a bit of a combination factor however if the model felt reasonably harmonised and 'normal' at slower speeds and the effect was related only to increased power then down thrust sounds like a factor. I would however also rectify the forward cg to its normal position as this will re harmonise the control authority at all speeds, particularly a loss of elevator at slow speed, like flaring for a landing. I would expect the sort of down thrust required to have a pronounced downward pitch to be quite visibly evident so worth checking.

[Dave Miller]

The first thing to do is to move the C of G to the correct position. You cannot deal with more than one factor at a time.

[crispin church]

as dave miller said do one at a time cog first

and check prop with the tail level

[John Keywood]

Thank you very much for the advice every one. I have sorted the C of G and the thrust line does not look far out. As you say correct one thing at a time.

Thanks again for your help. I will post the results after my next flight.

John