Turbo islander trim

[taildraggin68]

Lots of climb performance, but trimming for level flight requires nose down trim almost to the stops even with cruise power set. Otherwise, a very nice islander. 

[diamonddriller]

I agree.  Very difficult to trim properly.   Just to double-check, I reloaded a few minutes ago.  The plane was off the ground before I could even think about pulling back, and then I made sure I was in neutral trim and left it.  BTW, it would be nice if the plane did load with the trim set in neutral - just a thought.  The nose was pointing skywards.  Reduced power and rpm to recommended 2030 , and waited.  Still climbing with the VSI nudging the stop, almost - if not hitting it.  So, started to apply down trim, and left it.  Huge oscillations.  More down trim.  Still climbing like mad. Hit the max down stop, and it is just about level.  "Okay,"  I said to myself, "Let's see what the autopilot does."  I trimmed up a bit and then turned on the autopilot, selected altitude hold and watched the trim wheel and indicator, and waited. The trim wheel whizzed round, and the indicator showed maximum down trim - right on the stop!   Even then, there was a slight tendency to climb, but the a/p did level it off.  So, hand flying a 500 fpm descent requires a large drop in power, when the speed also bleeds down to a ridiculously low.  Trimming versus pushing down with the joystick, etc. - all tricky.   Not sure why.  The avgas version is a peach to fly compared with this. Odd....  Otherwise, it's very pleasant.  I was flying it with just the pilot, and the default fuel load.  W&B looked fine.   X-P 11.51 on an iMac - and it was the same trim problem in OpenGL and Metal.

[Coop]

Taking a look into the trim to see if we need to add more authority there. 

We haven't heard of cases with such a severe runout of trim, those extreme circumstances sound like either the flaps are still out at too high of a speed or the engines are above torque limits.

[taildraggin68]

15 minutes ago, Coop said:

Taking a look into the trim to see if we need to add more authority there. 

We haven't heard of cases with such a severe runout of trim, those extreme circumstances sound like either the flaps are still out at too high of a speed or the engines are above torque limits.

Flaps up take off, cruise power, takes getting below 75%n1 and still forward trim to the stops to get anywhere near trim for level.  Will try more testing tonight. Default weights and fuel. 

[diamonddriller]

I'll also run another test tomorrow, but my flaps were up too, and I made the point that I had even dialled back the power - maybe not enough, though???

[taildraggin68]

Trim image..

[jimid]

Experiencing this also, lots of nose down trim required in level cruise.

[TS_Ulrich]

We're adjusting the trim slightly for 1.0.1. Let me suggest changing your passenger configuration a bit to get more forward weight in the meantime.

@taildraggin68You still have a half inch of trim left in that image, by the way. And you're also heavily aft loaded so I'm not surprised you need so much down trim.

[taildraggin68]

@TS_Ulrich I agree but that is the default loading. Thanks for looking into this though. 

[diamonddriller]

I put some more forward weight in, but it didn't make a lot of difference with the trim setting.   It's quite easy to throw the CG out of the envelope with some loads, and I find the W & B pdf very interesting.  I'm curious as to where the datum is.  I flew RW in a Trislander, and remember the prop (tail support) they put under the tail on the tarmac, so it wouldn't drop the tail till they had some weight up front.

If you just had the pilot on board (surely not unusual), would you really expect to dial the trim all the way down to maintain level flight?  That can't be right. Or is it???  Surely, one designs the trim so that you have a lot of leeway at each end of the usual expected area or range of travel.

 

Edited January 31, 2021 by diamonddriller

[Jim Lynch]

The BN Islander Turbine is a great plane as far as looks and systems, but oh my God it is worse than a Boeing 737 Max 8 for wanting to point its nose way up. There is something definitely strange about the trim and the power.  you have to keep pushing forward on the yoke to keep the nose down and the trim is at the nose down stops. I also find I have to keep reducing the condition levers while in flight along with the throttle in order to keep flying without climbing. Its nearly like you have to use the condition controls like prop pitch controls to fly level which should not be the case.

[diamonddriller]

Yes, Jim.  I'm sure they will fix this, as it is too tiring to hand fly, and all the juggling with power and the condition levers cannot be realistic.  It's around usable with the autopilot, but I'm hanging on for the update, to be honest.  Unusual for TorqueSim not to have noticed this anomaly.

[Jim Lynch]

I think I will leave my BN-2T in the hanger until they come up with a fix. It is unusual for TorqueSim not to have noticed the problem however, I am sure they will solve the problem after all they make some of the best aircraft for Xplane, i.e. SR 22 &  BN-2.

 

[Gentfam]

Just to say, I bought this on Saturday and have had the same trouble with the trim as described above. I got the plane to fly level on the autopilot and it also then pushed the trim right way down to the maximum; and it still had troubles not to climb, unless I dropped the speed to 120knots or so. Therefore I also feel it needs some adjustment, especially compared with the avgas version, which is a joy to fly. 

Thanks in advance for any help.; Brian

[Coop]

Yes, we have a tweak for this in the works.

[Steve M]

I've had the same problem with trim, having to set full nose down to be able to fly the aircraft with only one pilot. As a temporary measure I have found that it will fly level with 1.5 nose down trim if the C of G is set to -25 inches in the X-Plane weight, balance and fuel panel when loading the 2T. 

It still took a bit of juggling to set the trim for level flight but made the aircraft more flyable.

Steve M.

[diamonddriller]

@Stevev M Good idea.  Works a treat    

[Digingsw]

Yes good idea, thanks @Stevev M

 

[Jim Lynch]

I did a test flight with the 1.0.1 version of the BN-T2 to test out the trim problem that I have with the aircraft. During the test I decided to fly it with only one pilot, no passengers, no cargo and both fuel tanks half full. Abnormally light in other words. At takeoff I set the controls:

Torque - 80%

RPM - 1800 (manual says 2100)

Trim - (-2)

Flaps - TO position

The climb out to 4000 feet was steep but manageable. At 4000 feet I retarded the torque to around 60% and retarded the condition controls to around 1700. The manual says to leave the condition controls at 2100 yet the You Tube video shows the condition controls being moved back to about halfway between full forward and the indent. I adjusted the trim to -3. The aircraft flew quite well mannered with just a slight climb tendency.

I still find it a great aircraft and fun to fly once you find your right settings.