If electrics go off in a SR22 one will have many other stuff to worry about not just trim, especially in weather or the kind of missions the aircraft is supposed to fly, hopfully you can pull the chute without electric if loss of trim is paramount to stability?
But I doubt a sping loaded trim is that problematic for speed stability as stick position and aerodynamic forces will remain same, so you are only lacking force feedback: some practice in the sim with a 10£ joystick/keyboard and some gym workout may help…
The electric trim works very well and is smooth and effective.
In the event of a total trim failure the handling is actually fine and the loads are not excessive. You should expect to explore the envelope during a conversion.
The chute is entirely mechanical.
As unlikely as total electrical failure is (two alternators, two batteries, duplicated essentail buses), in IMC the chute is the answer as the standby AI is also electrical. As far as I am aware none of the models have a manual T and S, albeit it would be easy to fit one, as well as a standby AI with its own backup power suppy if you were that risk adverse.
All SR22s have both trim motor and autopilot servos, only some early SR20s lack servos.
That is interesting because in most GA planes where an autopilot is installed, the pitch trim is done by the autopilot trim servo. The yoke trim controls just tell the autopilot computer to drive the trim directly. The SR22 really has two separate motors driving the pitch trim mechanism?
What was the thinking behind removing the trim wheel? I suppose it simplifies the cable runs because the trim actuator(s) can be right far back in the tail so you avoid the long trim cable run.
In most RVs the elevator trim is a small servo (installed in the elevator) driving the trim tab. The autopilot use a separate servo driving the stick/push rods (AFAIK). On microlights the trim tabs are usually controlled by a RC servo. If you have no trim tab, I guess the autopilot servo can also function as a trim?
Peter, I think your surprise at the lack of a trim wheel is rooted in the fact that you don’t realise there is no trim tab.
All the trimmer in a Cirrus does is apply a certain amount of spring loading to the side yoke. It’s not an aerodynamic trimmer – so there is no trim cable etc.
All the trimmer in a Cirrus does is apply a certain amount of spring loading to the side yoke. It’s not an aerodynamic trimmer – so there is no trim cable etc.
Which by the way is handy as during ground checks it gives you a direct feedback that it actually works
I agree it is very useful. I have also noticed that sometimes those who complain about the sidestick are those you find arent very precise about using the trim. I have found that flying on the sidestick is a very pleasant experience, and it really isnt the case that the aircraft should be flown for as much of the time as possible on the A/P.
stevelup wrote:
All the trimmer in a Cirrus does is apply a certain amount of spring loading to the side yoke. It’s not an aerodynamic trimmer – so there is no trim cable etc.
Sounds like the same trim system as on my Onex. It’s one of the things I don’t like about the design. With a real trim tab you will have redundancy in pitch control. Another option offering redundancy is the same system as the Cub; With the trim wheel you adjust the incidence angle of the horizontal stab with a jack screw. Same system as used in the B737 with various success 
That is interesting because in most GA planes where an autopilot is installed, the pitch trim is done by the autopilot trim servo.
Is that right? Legacy autopilots like Altimatic and Bendix King have a separate trim servo. I have a spare in my cupboard.
Has that changed in more recent autopilots?
We had elevator trim failure in the Corvalis. Like the Cirrus, it has no manual trim.
Having flown the Cirrus 60-70 hrs by the time I started flying the Corvalis I had almost stopped worrying over the missing manual trim. After all, both types have very good electric redundancies. But there was only one trim controller unit, and that one failed in flight, running the trim full nose-up before the pilot had time to find out what was going on so he could have pulled the trim circuit breaker. Obviously the autopilot could not be used, and it took reportedly a very strong push on the stick to maintain level flight until the pilot reduced to approach-like speeds.
