Smart Airstart Pitch Trim

[Frederf]

This is a feature request of sorts. When starting in the air in a MiG-21bis the pitch trim is at the zero position (same as when starting ramp). This results in a hands off dive at any airspeed with slower being more violent. The engine shuts down and overall the user has a bad time.

 

Instead the module could take a few parameters at air start initialization and set the pitch trim to a reasonable approximation of level flight, at least enough not to flame out the engine. This would improve the user experience and I think other modules do this already.

 

Example data for 5km clean configuration where axis tuning was used to limit the aft stick deflection and speeds were found for 0-5 increment 1, and 10-50 increment 5 percent deflection. For example at 678 km/h (IAS F2) and the stick 10% aft level flight was maintained.

 

In a simple airplane a simple function strictly of IAS would produce very good results. Because of the variable lever arm to the stabilator it's position between maximum and minimum probably has a sizeable effect on the correlation between speed and trim. Other factors such as gross weight, external stores, weather, etc. probably also play a minor role.

 

With some investigation a suitable equation of a small number of variables should be able to be found without much difficulty.

[Bogey Jammer]

+1

You can use your spreadsheet software to find the coefficients for a polynomial regression very easily.

However the external stores have a huge impact on this aircraft's flight dynamics, but I suspect the main criterion is the CoG position, to be verified.

[-Rudel-]

I noticed too....sent to Dolphin to look into.

[KilledAlive]

Honestly I circumvent this whole endeavor by just screaming through the skies at 850-900km/hr, no need to trim at all at those speeds!