Hi Everyone,
This is a short topic. I 'm having the most difficult time to track desired vertical speed with A2A Comanche. It does’nt provide vertical speed control in it’s autopilot unit. Once you’re in lateral mode, you have to make it work with elevator trim. I’m having difficulties during approach. Even at a constant horizontal speed and with fine elevator trim adjustments, the vertical speed fluctuates crazy. The reason might be bursts of wind and turbulant weather around. But it totally is ruining my joy of flight. I can’t get my eyes off of the vertical speed indicator.
Do you have any suggestions for that?
When doing a visual approach pick an aiming point (runway threshold or even before that on a short runway or the “numbers” on a long one) and fly to keep it stationary on your windscreen. The only instrument you need to look at during landing is the speedometer. Trim so that you don’t need to apply any (almost) forces to the elevator.
2 Likes
Final approach is fine. The difficult part for me is the lack of VNAV during descend after TOD. I have the VNAV through GTN 750Xi unit. Just can’t easily track the desired VPATH.
I suppose it depends if you’re flying VFR or IFR. If VFR I wouldn’t focus on it too much. As long as it feels good and you don’t bust any airspaces or minimums. If IFR then keeping your eyes on the instruments is what you should do 
But even then I wouldn’t focus on having a perfect descend profile. It’s not an airliner, if it’s turbulent / gusty it will get thrown around. As long as you’re at the altitude you should be, when you should be, it’s fine.
1 Like
Don’t worry about a specific vertical speed other than keeping it within a reasonable range for this type of airplane (like 500-1000fpm). Generally you’re not following VNAV/PTH descent cues in a plane like this, so it’s kind of a reach (not impossible, just a reach) to be emulating it as such.
But the key is to trim for the airspeed you want and use power settings to establish your desired rate of descent. The trim tab is working in concert with the airflow (read: airspeed and propwash) to maintain the equilibrium of the stabilator at a particular angle of attack. There may be minor adjustments in both pitch and power in the end, but try this:
Trim for 140mph, level flight, cruise power, and pull the power, the airplane will want to regain that 140mph, but without the power it will be descending while doing so, going through oscillations while it tries to stabilize at that airspeed. Dampening the oscillations with the yoke will establish the equilibrium more quickly. Once it’s in a stable descent, add the power back in, and eventually it will oscillate its way back to level flight and 140mph. You can also do this the opposite direction with a climb from cruise, by adding power.
6 Likes
Thank you both. Will keep these in mind for the next time.
1 Like
The vertical speed indicators in most GA aircraft have a lot of lag, and I assume A2A has modeled this well. Trying to “chase” the vertical speed in a real GA aircraft never works well. The VSI is the least sensitive performance instrument.
It is best to try to hold a specific pitch attitude to your aiming point on the runway, and control rate of descent with engine power.
1 Like
The best way to set a vertical speed in cruise is to adjust the elevator trim and power (as noted by @HalberQuacky), not to use the yoke.
Remember, too, that most controllers have much less range of motion, and different range of motion compared to the real yokes and sticks in planes, not to mention there is zero physical feedback, which makes using these controllers wicked hard compared to real flying.
I find myself putting the slightest amount of back pressure on my joystick accidentally all the time, and it’s really annoying. When I’m really flying, my vertical flight path is controlled almost totally by power and trim, and I keep a finger on the yoke to keep the plane from rolling when wind gusts hit. (ok, sometimes my hand 
“Yikes!!!” 
). Because of the physical feedback, real flying in this regard is soooo much easier.
4 Likes