William Robison

My Feedback: (3)

Just a short one this time, it's a simple thing.

Had a PM asking about lateral balance and trimming for an imbalance. Basically, this note is my answer.

Nose to tail balance is used to make the plane stable, using downforce from the stabilizer/elevator to control airspeed. If you understand that you are well on your way to understanding lateral balance. But it's not necessary.

If we have one wing heavier than the other, the heavy wing is going to have a constant tendency to drop. Since it is constant, it will not change with airspeed.

But the aileron effectiveness does change with air speed. So the amount of aileron trim that will hold the plane level at one speed will be too much if we speed up. At the same time, it will not be enough when we slow down. Result? Constant change with a change in speed, and we can't trim for it.

Lateral balance is at least as important as fore and aft balance, and has to be much more exact for the airplane to fly at its best.

Bill.

Robby

My Feedback: (18)

Uhmmm,, william,,
You sorta left one one tinsey winsey little ingredient of Lateral
balance .. Torsional rotation... This has to be compensated for
as well.. Thankfully, R/C is effected less by it.. Well, probably,
more easy to correct would be a better way to put it..

For those who may ask, torsional rotation is when too much
power is applied causing aircraft to rotate <axial / lateral >..
This is why some manuvers are better done in one direction
than the other..

William Robison

My Feedback: (3)

Robby:

Thanks for the comment. But... Always a "But," isn't there?

The torque induced rotation, the helical path of the slipstream, and the old fellow that gets blamed for everything including running out of fuel, P-factor, have no efect on the airplane when flying power off.

And that's where lateral balance, or lack thereof, will most assuredly and quickly bite you on the posterior.

Bill.

Robby

My Feedback: (18)

Theres that damn 'but' thing again.. *sigh* ...
But you are correct.. Well,, there is another but,,
In a power off situation you still have the prop pitch creating
a rotational force,, more effected by a single than a twin,
thankfully..

Ok,, yer turn.. Next 'but' ...

<no 'moon' shots, BTW>

Oh, hey.. I ran outta fuel on one of my gass'r's today,, not once,
but three times... Thats da bad news..
The good news is,, I had landed, and was just to or in pits when it died,, each time..
Was funny, first time I thought there was something wrong with
motor because it -never- dies.. I spent about five minutes
checking it out when I got to fuel and notice,, EMPTY...

Ok, class,, can we all say *DUH!* ..

William Robison

My Feedback: (3)

Robby:

I know you are familiar with GA planes, remembering we have flown from the same field in years (many) past.

An engine out in a light plane. The second thing you do, after first being sure you have airspeed, is to stop the prop from windmilling if it has not already done so. Why? Because the windmilling prop has much more drag, and greater aerodynamic effect on the plane than a prop not turning.

BUT (And here's the but) our little engines NEVER windmill, they stop. And then the only effect the prop has on the flight of the plane is a very slight tendency to roll right - the opposite of the normal running engine's torque effect.

And congratulations of saving the plane when you ran out of fuel, but running out after landing is cheating.

Bill.

Robby

My Feedback: (18)

Correct --------
A disc has more resistance than a 'stick' <prop>.. This can be
seen on our R/C planes by putting a bigger diameter prop,less
pitch, on. It will pull hard,, and it will slow the plane down better,
and in some cases,, hard and fast.. But a good way to learn to
fly a heavy plane as something along the lines of a warbird.. Fly
it till it lands...