ceecrb1

Ok so i´m loving my great planes extra 300 sp...

I´m trying to play with the C/G a little. I currently have it stated at the manuals recomended starting point.

Now here is where it gets complicted (for me).
I KNOW that you always set C/G with an empty tank but I just CANT get anything "3d" out of this plane, its far more pattern-like.
Would it be better to set C/G with the tank just half full? As lets behonest, I set the C/G (empty), fill the tank and in a 15min flight, from full am using about 20% of the tank only with the os55ax, so i´m still flying & landing WELL stocked with fuel... ie nose heavy.

ALso, what I really dont understand, like I say I want to move the C/G farther back as I am now very competent with the plane and would like to get it more into a 3d role...
TOday I added some weight behind the wing and moved the C/G from the "starting point" to half way towards the manuals farthest rearward point.
The effect in the air, well I didnt notice any really.. but .. Landing.. the damn thing became a "floater" and it took me about 5 attempts to get it down onto our very short runway. I always thought this was more indacitive of a plane that is NOSE heavy, not tail heavy???

Can someone give me some insight as to what is going on?

bkdavy

My Feedback: (1)

Most planes recommended cg is slightly nose heavy to improve the chances of a successful maiden flight. Once you've flown the plane, you can adjust the CG within a range to achieve the flying style you prefer.

The plane feeling like a "floater" as you move the CG back is related to the tendency of the plane to drop the nose. A plane that is nose heavy will drop the nose at some point as the horizontal stabilizer loses its force to hold it up. With a neutral CG, the elevator doesn't have to apply much force to hold the nose in position, so the tendency to drop the nose is reduced, giving it that "floater" feel. As the plane becomes more tail heavy, other forces come into play and the plane becomes less stable, so don't overdo it.

For most aerobatic planes with symmetrical wings, the neutral CG tends to be right along the thickest part of the airfoil, which generally corresponds with the wing tube or main spar.

As for "tank empty", balancing with the tank half full is pointless. Always balance empty as this is the most rearward CG, and the most unstable condition for planes with the tank ahead of the CG.

Brad

ceecrb1

Excelent, basically from what your saying i´m dead on the C/G I need for being able to mix 3d and the pattern (like I was practicing today)

I now only need to extend the throws out to the manuals "3d" settings and give it a real bash tomorrow... They are currently half way between "high" and "3d" as stated in the manual.. I was increasing it is small doses too..

The floating landing is a reall pain in our club, as the runway is very short and at the (whats normally for the weather here) upwind area, just at finals, is an orange grove, planted on higher ground than the runway, so there is always a last minute dive where it accelerates and foats off down the runway (most planes in the club not just mine).

pimmnz

'Floating' on landing is simply too much airspeed. Take the model to a safe height each time you move the balance and carry out your normal stall checks. You will soon see the slow speed effects of rearward balances and be able to better judge the correct approach speed. Always use 'up' elevator while landing, of course, 'down' will only increase your speed, and 'float'.
Evan, WB #12.