MU-2 pitch trim

[andyw248]

From what I'm reading about flying the MU-2 on final approach it appears that ~120 knots would be a good approach speed with flaps set to 20 deg, and torque set to ~20-25. Flaring will get speed down to ~105 kts, without cutting power too much, resulting in a soft touchdown. Works well for me in the sim, except that I can't seem to trim the plane to 120 kts; just running out of trim range. Does this correspond to the real world behavior?

I played a bit with planemaker and changed the settings in the control geometry window as follows:

- elevator trim down then up: down 0.25 -> 0.35 / up 0.55 -> 0.75

- trim speed ratio: 2.00 -> 3.00

This makes the elevator trim a bit more sensitive and extends the trim range. Makes me feel more comfortable on final, but this might just be my personal opinion.

Cheers

Andreas

[timdickson]

Similar experience. (Using X-Plane 9.31 on 3ghz intel dual core running Vista64bit CH products flight stick pro + pedals). Both on the approach and some climbouts run out of pitch trim Would also be interested in the answer to ypur question from those "in the know".

Being an X-Plane newbie I'd like to follow your example but slightly nervous twicking parameters in PlaneMaker!

TIM

[timdickson]

Also take the oppurtunity to thank "Tkyler" for his X-plane masterpiece !!!

TIM

[tkyler]

thanks for the compliment.

Regarding running out of trim, this would probably depend on your glide slope angle.  I agree the trim almost limits out on a casual approach...this due to the fact that x-plane does not model trim exactly, but only uses a 'percentage' of elevator travel as the trim travel. 

So I could simply "up" the percentage of elevator travel and that would have the end effect of having more trim authority as andy248  did.  That's the simplest solution.

The reason I guess I never really caught it was that the approach angle in the MU-2 as practiced is typically higher than normal and we all came in nose low with the flaps acting like air brakes almost.  This xplane version is designed to fly with neutral trim around 220 kias...so at slow speeds, I could see it being nose heavy and maxing out the elevator trim, but because I just never seem to fly that way, I guess I never notice it.

Regarding the 120 kias approach speed...the "in the know" crowd calls that speed a bit slow...more like 130-140 through the middle marker and about 120 at the inner marker and 105 +/- about touchdown.

The only time we'd fly the "proper" glide slope was during IFR ops and I didn't experiement enough during that time to see what's what...besides, we always had 1000+ lbs of cargo and the MU2 is trim sensitive enough that the distribution of the cargo would probably have some effect also.

In the MU-2...once it's trimmed nice and level...a pilot can lean forward and get the plane to nose down. 

So If you prefer to fly that profile, then you can change the trim percentages as Andy did..it's not hard at all...or you can just fly a bit steeper profile.  If you'd like to change your trim settings, let me know and I'll put some "how to" screenies up here.

[timdickson]

Thanks for the information. I'll try and fly it like the "in crowd",

TIM.

[andyw248]

Thanks for the comment! Yes, 120 kts on final feels like the lowest possible speed, below that it would get really mushy.