I have just patchiest a Black Horse Cap 232 the C G it spot on to the instructions but when i get it up in the air it nose dives I trim it and flys like a dream. question is should i play with the battery position or leave it heavily trimmed..?

last weekend I converted a flyng wing to electric.  The model, a Wingamajig, is one of my oldest still flying, and once I'd taken off the cox 049 and glued on the mountings for the 100w electric, I realised I'd got no idea where it should balance.  I really should have marked the CofG before messing with anything, but hindsight is always 20/20 isn't it?

What I did was to put the battery up front so that it was definitely nose heavy,  get it gliding about right from a hand launch, then switch on the power.  trim for staright and level at cruise power and we're ready to do a test or two.

First to check the CofG - once I'd got plenty of height (air underneath is your friend, air above is a waste), I switched off the power and pushed the nose down about 45 degrees.  The model pulled out of the dive pretty quickly - less than 30' at a guess, indicationg that it was nose heavy, hence needing a lot of up trim to fly straight and level.   If it had stayed in a steady dive I'd have moved the battery forward a little, if the dive had increased I'd have been worried as I'd be running out of 'forward' to move the battery to!  For this model I'd like to get it  so that it will sort itself out without much intervention from me,  for something more aerobatic (Acrowot) I'd be looking for it to keep a constant attitude once put nose down.  

Next , wind up the power - in this case the model started gaining speed and losing height, indicating the thrustline needs adjusting.  ideally I'd like it to gain a little speed and climb at a steady rate under power. 

I hope this is some help Robert,  

Thanks for your help,

Maiden flight. I’ve left the CofG marks on the wing until I get it to fly right by the way. With the batteries next to the tank & receiver and (forward) & on full throttle it flew with a lot of up trim throttling back to cruising speed the nose dropped.  And extra trim was required to keep it level. (not the result I required )

When I was on the return leg & put the throttle on idle it fell out of the sky like a brick despite full up elevator. I just managed to get full throttle on & pull up in time but on the second attempt the engine faulted & the ground bite it hard resulting in undercarriage damage.

Second flight. With the batteries as fare back as possible & the CofG still on the same marks & trims all set to 0 resulted in my cap nearly hanging on the prop from takeoff & me having to input full down elevator to try & gain air speed wiliest  fighting to keep the wing level this as you can appreciate left me with very little options & I just managed to get the plane over some trees/bushes  next to our site with the engine still at full tilt & very little control nose still up in the air again this resulting in damage to the wing/ undercarriage.

I will persevere and find the perfect CofG