Tail heavy DP Extra?
 

My first flight was a close call. Very windy roller coaster ride kind of a thing. My control was so bad that I blamed the new radio. Now that I'm socked in with rain and have had a chance to over-analyze the situation, I suspect balance is the problem.

My initial flight was with the cowling off. The balance with cowling off is 6.25 inches. With the cowling on, it's 5.75 and with my Rx batt forward, it's 5.5. The instructions say 5.75 is the target.

All my previous experience has been that the recommended balance point is alway very conservative (too far forward). I'm wondering if the Patrick Extra may be right-on or slightly aft. I wouldn't think that one half inch aft would produce an uncontrollable airplane.

BTW, all throws are at the recommended low rate and I have a 20 oz tank at the stock forward location.

What is a good balance point for the DP Extra?

RE: Tail heavy DP Extra?
 

According to the addendum on DP's site the 'conservative' balance point is 5" back from the LE.

My new-to-me Extra is balanced a little behind the 5.75" point with everything but the spinner and prop. This is one of the first0-generation (tail-heavy) Extras with the canopy held on by a buncha screws. Engine is a BME 50, elevator servos are in the tail, rudder servo is in the tray. I had to move the rx and battery up in order to get it balanced at this point - and that's with a heavy engine.

Maiden flight was to have been this past Sunday but we couldn't get the engine to fire. From the desciption of your flight this may have been a blessing!

Going to add a bit more weight to the nose for the first flight.

RE: Tail heavy DP Extra?
 

DP web site makes vague reference to a 5.0 inch balance point. The instruction manual clearly states 5.75. I don't see any official looking addendum though. I'm confused.

RE: Tail heavy DP Extra?
 

I flew this plane all summer with the CG set at 5 5/8" with everything in the stock position. Really like the way it flies and does 3D great.

Here are the pics.

RE: Tail heavy DP Extra?
 

Mine was a handfull to fly at 5 3/4" and very hard to land cause it wanted to balloon in. At 5" it is easier to handle and still feels tailheavy. Still wanted to balloon a little so I drop the airlerons 1/2" on landing and it solved the ballooning problem. At 5" I have slight climb while inverted which is what I like. My biggest problem now is the plane wants to snap right with heavy elevator input like a wall. Now that I know its coming, I can handle it but don't like it. Version 1 with Taurus 52 with 100 or so flights.
Paul

RE: Tail heavy DP Extra?
 

Holy crud! I was flying at 6.25. No wonder I had problems. Winds were gusty 10-15 too. I'm getting quite disappointed now. I was going for a light glow set-up with an OS 1.60. I have the new version kit, one mid-mounted elevator servo, and battery mounted to forward tank position. My balance point is now at 5.50. Balance with full fuel tank is 4.75. Pleases don't tell me I have to add weight!

RE: Tail heavy DP Extra?
 

DP site reference

Lots of anecdotal references here on RCU by guys with DP Extras moving their CG *forward* after the plane's initial flight...

RE: Tail heavy DP Extra?
 

DP made a change to the current revision Extras (with the hatched canopy) - the wing has been shifted back to make the plane easier to balance when using light engines.

You may be OK now. Wouldn't hurt to move the CG a little more forward, though. At least while test flying.

Its easier to move the CG back if you haven't broken the plane :)

I know I'm moving mine to 5". Hopefully swapping the 5-cell 1400 mAh rx batt for a 5-cell 2400 mAh one will do the trick...

RE: Tail heavy DP Extra?
 

On my version 1 DP Extra, I fly at 6". If you're flying a version 3, 5" is good.

-Ben

RE: Tail heavy DP Extra?
 

Ben Diss, I don't understand. Isn't the old and new revision basically the same except for a few minor changes. An acceptable balance point for each version should also be the same.

RE: Tail heavy DP Extra?
 

ilikeplanes-

No, the position of the wing was changed with version 3. This is what visioneer_one was saying also.

-Ben

RE: Tail heavy DP Extra?
 

I agree, even if the wing was moved the CG would not change. I am using about 6" back. I accidentally had it about 7" back and it was kind of squirrelly :-)

RE: Tail heavy DP Extra?
 

Rebalanced mine last night. Used a 2400 mAh 5-cell rx pack, mounted under the fuel tank.

CG is now right near 5" according to my non-calibrated thumbs.

Bring on the weekend!

RE: Tail heavy DP Extra?
 

Hi all,

I have latest version. Balanced at 5.75. Had 3 flights on it. It is the smoothest flying machine I ever had. So 5.75 is just fine. I would not try 4.75. Wrote everithing about mine in the giant scale forum. Post names DP extra + ZDZ50 + KS-86.

pceagon: I have the same snap problem. Let me know if you figure out how to fix it (should I have to add weight to one of the wing tips).

RE: Tail heavy DP Extra?
 

OK, having thought about this some more I see that the CG in relation to the wing shouldn't change between versions of this model.

FYI, DP moved the wing to make it easier to balance. At 6" from LE, inverted flight takes very little down to hold, pullouts from loops and vertical maneuvers take a little up to pull out (versus pulling out on their own) and the amount of rudder/elevator mix to correct knife-edge is less that with a forward CG.

-Ben

RE: Tail heavy DP Extra?
 

The weekend has come.

Maidened the Extra yesterday with its 5" CG.

It flew well, but was indeed it was too nose heavy.

After flying it around for a bit I brought it down indending to shift the CG back. This was difficult as I couldn't slow the plane enough. Unfortunately I snagged a thick clump of grass and flipped the plane onto its back. Spread the landing gear and put a crease in the wing tube.

I'm going to use this as an excuse to replace those items with CF versions. :)

RE: Tail heavy DP Extra?
 

I also managed to get out this weekend. I had a sort-of successful flight. I now wonder if all my problems are related to too much elevator authority. I have mine set at 3/4 inch measured at the front of the counterbalance. It is extremely pitch sensitive. I did have a flame-out of my OS 1.60 and it glided back very nicely. No ballooning or anything like that. Just settled into a nice glide slope with a little back stick.

Anyway, what is a good elevator throw for basic precision flying and at what point should it be measured?

RE: Tail heavy DP Extra?
 

I'm using the recommended low rates introduced in the manual. Very smooth, and not pitch sensitive (but I'm used to give very small inputs on the sticks).