After many builds with never a problem... I have two airplanes in a row that do the same thing which makes me think I somehow have lost the formula when setting the firewall angle, CG or maybe the manuals are wrong ??

Here is what I have on an Aerotech Extra (DA50) and a Columbo Anderson Extra (3W-75i) they are the lastest planes I put together and they both do the same thing..

Fly plane at full throttle... chop throttle.. plane does not climb or dive, tells me incidence and up/down thrust are OK
Fly plane straight up plane stays straight even at WOT - tells me right thrust (mixed in with rudder) is dead on
Fly plane in down line, it pulls to canopy slightly, mixed out with down elevator (pretty normal )


CG on Columbo - dead center on tube, right where manual says. 19 pounds 14oz FUW.
CG on Aerotech - in the third fifth of the range (i..e if range was 1-5 I'm at 3) 16 pounds 9oz FUW
Incidence on both planes are zero/zero.

The planes FLY very well with no bad tendencies whatsoever. Where I am having problems is on landings. I come in on approach, and all looks great until I get over the runway. When I reduce and/or cut the throttle the plane balloons up way to high to land. I have to feed in down elevator in order to compensate, which usually ends in overcorrection and a missed landing. Add any headwind into this equation and its very hard to get the plane on the ground. The plane cannot land hot, it will continue to fly, so something is definitely up.

To try to reduce the sensitivity of the elevator, I have enabled a landing flight mode - the elevator throws are very low (15%) and 40% expo. The elevator still seems a little sensitive but not hypersensitive as it was with no expo and higher rates. Again, in normal flight everything is fine and even on high elevator maneuvers the planes do not snap.

So.... does this sound like a CG issue or could it be I need to add some up thrust ? The CA Extra has some upthrust built in. The Aerotech has none.


Honestly, these planes should be easy to land yet they are harder to land than some of my previously (and much smaller) planes. I battled a 20 mph head wind yesterday while flying the extra and on about the 7th attempt to land it I drifted slightly off the runway and caught the gear on the edge of the pavement. I tore out the gear block when I hit a rough spot in the dirt. I was very lucky as it was a clean break with no other damage to the plane. The plane is already fixed (beauty of a kit) but I really don't want to go through that again.

One last thing. Early in the day before the gale whipped up, I did an intentional dead stick landing (i.e. lined up with the runway and cut the ignition) it was a LOT easier to land and came in very predictable.

I'm thinking upthrust... anyone else??

DP