Hey guys,
I just finished running my new DA50 and boy what a powerhouse!! Turning a Mejzlik 23x10 @ 6950! But I have a problem. It about shakes my plane to death!! Everthing is balanced (spinner/prop). Anybody got any suggestions as to what may be the problem? This is my first gasser, so any input will be greatly appreciated. Thanks!!!!

usually it shakes really bad if it is to rich.try to lean it out on the high needle and set it for top rpm.

Just a thought...... are you running the engine with the wings and stab on? The reason I ask is because a friend was having the same problem due to the plane not being fully assembled.

bn120,
That is something I was thing about too, but simce it is a brand new engine (about 10oz through), wouldn't it be better to be rich? Or should I do it like glow...put a tach on it, lean it till I get a good top rpm, then back the needle out a little.

LUNATIC,
That is a very good point. I had the stabs on, but I didn't have the main wings on. I'm gonna fly it this weekend, so time will tell. I can see where that would help distibute the "shakes" though....

Thanks Guys!!!

Without the main wings on, you will have much more vibration.

The wings help to dampen the vibration greatly.

PUT THEM WINGS ON IT.........

Being that you are new to gassers, a "little" rich is better than a "little" lean. Gassers should be run VERY NEAR PEAK, but pay CLOSE attention to it. Check the spark plug FREQUENTLY. Pull it out and look at the end of it. If it is BLACK, then you are too rich. If it is WHITE, you are too lean. A well set up gasser will be TAN on the electrode.

One more reason to allways run the engine first on a test bench.
Keep it rich a bit on the high speed, but the idle is what is going to kill you with vibration and it should be leaned a bit until it gets better.

Humm!!!
roger i was told to put the motor in the plane and fly it. was told it was not nessecary to run it on a bench.

i'am new to gas also can you give us some of your input please

dennis

Dennis,
As far as breaking in the engine, they are right, you can do it in the air.
The reason I like to bench it first is to run it a bit and adjust it so that it will run decently, hence the vibration. Its a lot easier to do adjustments on the bench then in the airplane at first.

hi roger

do the setting's change once the motor is mounted in the plane with the cowl on

No they shouldn't change much, but you do need to do minor adjustments once in a while anyway.

Hi Dennis,
In the plane and fly it is right. That comes directly from DA. There is a reason for that. You want to break the engine in as it would be flown in the air. The only thing running one on a bench will do is statically load it and heat it up. Never run a GS model without the wings on...some models will exibit 3rd order harmonics, and you may one day find you are holding up a couple of sticks...what used to be a model. Everything is bigger on a GS model...the size, forces, power, flight qualities, and other things ad infinitum. When you test a GS model, test it ready for flight...even if you are range checking it, testing controls, or anything else.

...flyin a little higher altitude at present, but still...
flyin_low

I think you missed what I said, on the bench to do first setup and then on the airplane.

Ummm, nope, I was responding the the poster...check the quote again.

Sorry about that...

Buy 3 W

Roger, When pulling over the top of a manuever and slightly backing out of the throttle, I experience a slight 4 stroking effect on my Fuji 50........Do you think the bottom end could be to rich????? Thanks in advance for your help..... Skip

You can try and lean out the low end a bit at a time.

I agree !!!

if your moter was droped maybe the crankshaft is slightly bent.with all starting devices off and spark plug wires off,hold a scewdriver at top of cylinder turn prop till blade hits closest point without moving driver rotate prop to oposit side if the prop doesnt hit it the same may have a bent crankshaft