Salute
Depends what plane you are going to fly as to how many trim axis you may need.
For example, Spitfires and Hurricanes have trim controls for rudder and elevator, nothing for aileron.
109's have trim for elevator only, nothing for rudder or aileron.
If CLIFFS OF DOVER is anything like IL-2, you will be able to assign trim to an axis when it is enabled for an aircraft.
If you already have a joystick and rudder pedals, then what you need is a throttle to give you additional axis to assign for trim.
There are many solutions out there, here are a couple:
CH Pro Throttle
This has one throttle axis, it would free up the throttle wheel on your joystick to use as an elevator trim. Combine that with the wheel on your mouse, which you could use for a rudder trim. There is also a mini joystick on this unit which could be used for trim purposes.
CH Throttle Quadrant
This has six separate throttles which could be used to free up the throttle wheel on the joystick, or whose axis could be assigned to whatever trim you wish.
Saitek Pro Flight Throttle Quadrant
This has triple throttles which again could be assigned to trim purposes or free up the throttle wheel on your joystick.
You can also buy HOTAS setups which include joystick, throttle and rudder pedals if you don't already own a joystick and pedals.
For example, the Saitek X-52 system is a joystick and throttle. Combine that with the Saitek rudder pedals and you have a HOTAS setup:
There are also HOTAS setups available from Thrustmaster, Logitech and CH Products. (my personal favourites)
One thing people need to remember about CLIFFS OF DOVER, is that with complex engine management, it is going to require quite a few more control axis. By my understanding of the promo info released, the axis required would be as follows:
1) Throttle
2) Mixture
3) Supercharger boost level (players will need to be careful in their settings, too high boost with lean mixture will cause detonation and destruction of the engine. Low boost with too rich mixture will consume too much fuel as well as bogging the engine, and players who run high boost/rich mix all the time will find they will run out of fuel in very little time. Combat power should consume 4 times the fuel of of cruise settings.)
4) Prop pitch (for early Spit and Hurri, this will be a two speed setting, activated by a button, either coarse or fine pitch. Later Spits will be constant speed, with the player setting the RPM level, and the auto pitch adjusting to maintain that engine speed. For 109, this will either be completely manual, with the requirement for the pilot to ride the controls constantly to prevent overrevving, or if Oleg allows for the late BoB 109 to be modelled, which were very rare, there will be an auto pitch version of the 109)
5) Radiator
6) Flaps (only for 109's, Spit and Hurri flaps are either up or down, and would be activated by buttons. If 109 flaps are correctly modelled, they will take 30 seconds to fully deploy)
7) Elevator trim
8b) Rudder trim (Spit and Hurri only)