trim question

T

tonedog

Guest
when i try to trim the aircraft i never seem to get it spot on. for eg, if the plane is goin to the left and i press the trim left key once then it starts to move to the right and vice versa.

do u guys use the keys to trim as well? is there a way to maybe the keys a little less sensitive?
 
It really depends on the plane--they all have different personalities. However, some are rather more stable than others, which makes it easier.

On the left-right thing, aileron seems to be more what you need than rudder. I hardly use rudder trim at all, in fact.

Note, however, that if you're playing with the wind turned on, this can give you the illusion of being out of trim. If you're flying across the wind, your plane will turn downwind. The only way to stop this is to crab into the wind at the right angle.

Also note that every time the wind changes (evident by your airplane suddenly suffering a bad bump of turbulence), you have to find the new crab angle. And each crab angle requires a different trim setting.

Another thing to remember is that these planes appear to have an amazing ability to conserve angular momentum about the yaw and roll axes. Even though you move the stick to stop a roll, say, and return the stick to center once you're level, the plane will start rolling again almost immediately. You often have to go through this process 3 or 4 times before the plane settles down, and this is even if you're trimmed out properly.
 
rockmedic109 said:
Sure! An early form of Redneck cruise control. Small sandbags on the rudder pedals and hold the joystick with your knees.
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You omitted the piece of rope, that secures the stick from 4 directions

Actually some adjustments could be made, by the mechanic on the ground on some aircraft, on others nope

Very, very few could set any trim in the air.

The SE5a could trim it's Elevators in Flight

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They actually had an autopilot in 1917, but it was MUCH tooo expensive to bring to War :kilroy:
 
Are the default trims part of the flight models?

I have wondered about that since without tweaking the trim, the Camel is nose heavy rather than tail-heavy.

I set up my trims the way I think they should be on a quick flight for each new type and then always set those values before I take off on missions. I see this as getting the Ack Emmas to rig the machine to my tastes. The exception being the SE5a, which I have a few degrees of trim available in flight.

That's the way I do it anyway. But I would like to know if the default trims are important to the historic feel of the aircraft.
 
I cheat on a 'massive scale' so I'm not affected. But if a Bloke wishes to fly as they did, I can see the minipulation of the trim controls, while the aircraft is on the ground as they did, because two aircraft of the same type, were not identical.

Because I for one believe you should experience, differences in flight manners between a Sopwith Camel in 1917, and a Piper Cub in 1963
 
gimpyguy said:
I cheat on a 'massive scale' so I'm not affected. But if a Bloke wishes to fly as they did, I can see the minipulation of the trim controls, while the aircraft is on the ground as they did, because two aircraft of the same type, were not identical.
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Some OFF planes are so badly out of trim to start with that they suspend my suspension of disbelief :). I can't imagine that they actually flew them that way. For instance, the FE2 wants to roll left so bad as soon as it leaves the ground that you have to hold the stick nearly full right for the duration. Not only does this rapidly tire your wrist, it makes it practically impossible to turn right.

If I had that happen to me in real life, I'd do a circuit as best I could, land, kiss the ground, and then have my fitter take up a dozen or so turns on the aileron cable turnbuckle. I'd repeat this as many times as necessary until the thing would fly more or less level with the stick centered.

IMHO, this is exactly what the real guys did. That's why they were always doing test flights. Every time they took the plane apart for maintenance and repairs and reassembled it, all the control cables would have different tensions than before, so the thing naturally would be badly out of trim. So they'd do a few hops to make such adjustments, assuming the thing wasn't so badly wrong that it killed the pilot the 1st time (a depressing number of guys died doing such test flights).

So yeah, WW1 planes really shouldn't be trimmed in flight. But OTOH, I firmly believe that none of them actually going out on missions were as grossly off-center as some of the planes in OFF. Therefore, I have no qualms at all about applying enough trim to straighten out more or less shortly after takeoff. I figure this would have all been done before the mission in real life.

Note there's a difference between being out of trim and unstable. When a plane is out of trim, you have to hold 1 or more controls way off-center, in a consistent direction, constantly. When a plane is unstable, you have to make a bunch of rapid corrections in all different directions, constantly. An unstable plane can be in trim, if the center point from which all your stabilizing stick movements originate is near the center of the stick's movement. Thus, you can tell if an unstable plane is out of trim if this centerpoint doesn't correspond to the stick's center.
 
tonedog said:
when i try to trim the aircraft i never seem to get it spot on. for eg, if the plane is goin to the left and i press the trim left key once then it starts to move to the right and vice versa.

do u guys use the keys to trim as well? is there a way to maybe the keys a little less sensitive?
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Tone,

You'll never get it spot on. The trims are set up as a percentage, a percentage of what I'm not sure, but the smallest increment is .5. Most planes can be trimmed to close to hands off but not always completely. You can see the values if you turn the data portion of the HUD on. My procedure is after take off to trim ailerons to give basically level wings. Then I trim elevator to give a nice rate of climb. After I get these set I watch my course and I'll usually find it tends to swing to left, (gyroscopic procession and torque) I then trim rudder to correct the swing. Trimming the rudder will cause the aileron trim to be off so I then re-trim them for wings level.

Did these old crates really have trim controls?
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Flavious,

No not really, a few of the British planes had a variable incidence horizontal stabilizer. The Snipe the Se5a and I believe the Strutter had one. This could be used to help keep the plane from climbing or sinking when power was increased or decreased. However all the planes were rigged to fly close to hands off in some portion of the flight envelope. This was done with the rigging wires and changing the incidence of the wings and tail plane. For instance the Nieuport lower wings had different incidence angles to help compensate for the torque of the engine. What I do to simulate this is first I trim the plane as described above, then I write down the trim values for each plane. Then before take off I set those values and don't change them throughout the flight. This give me a fairly well trimmed plane at full power at a nice climb. But during just level flight I have to either hold some down elevator or reduce the power to keep it from climbing. Diving requires me to significantly reduce the power and hold heavy down elevator etc.

Scott
 
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