"Unsticking" the CJ4

[Leptinos 0]

After the reinstall I had two flights without problems. However the third flight revealed the discussed problem again.

Something I have probably noticed may cause the issue is the elevator trim. For the third flight I've trimmed the elevator from the top end of the green band into the middle of the green band. The fourth flight (without touching the trim on ground again) worked again without the problem. I played around randomly with the trim setting before and had the "stick to the runway problem" also randomly. Maybe this has caused the issue ...

Maybe someone can confirm this investigation independently.

Edited July 17, 2023 by Leptinos

[eslader 1,787]

I know this can be difficult in MSFS with windsocks 5 feet away from each other showing opposite conditions, but have you checked the winds? I wonder if maybe it's triggered by a certain wind condition that's being reacted to improperly by the flight model/control surfaces.

 

I've never had this happen, but admittedly haven't flown the CJ4 all that much until recently.

 

[Valeryo 0]

Hi!
I noticed a similar problem. My cj4 in a lot of cases does not want to lift the front chassis at speeds below 120. It is extremely rare for takeoff to occur in the correct mode, at a speed of Vr ~ 100. I've tried various ways, but so far nothing has helped to make the behavior of the aircraft predictable during takeoff.

[TexasGary 47]

I was aware of this CJ4 "runway sticking" issue from reading the forums, but fortunately it never affected me.  Until yesterday.  I did two CJ4 flights yesterday, and both flights had the same "runway sticking" issue as described above.  Just tried another flight today and had the same issue happen again.  I had not changed anything or added anything to the community folder, and my CJ4 setup and loadout was the same as always (flaps 15, trim center of green band, V speeds set correctly, CG in range).  Like others with this problem have said, once I got the plane in the air the rest of the flight was problem free.  I agree with Leptinos that it seems to have something to do with the elevator trim.  But if it's a trim bug then why doesn't it affect the rest of the flight?  Why only the takeoff?  And why does it just seem to appear randomly out of nowhere?  Very strange.

I am going to take Leptinos suggestion and try some flights without touching the trim wheel before takeoff and see what happens.  Ill report back here after a few flights.

 

[TexasGary 47]

OK, I just did some quick flights experimenting with some different scenarios and trim settings.  Here are the results:

Normal cold and dark startup.  Trim left untouched at the top of the green band.  Takeoff was normal (no sticking).

Normal cold and dark startup.  Trim adjusted to the middle of the green band.  Takeoff was normal (no sticking).

Start on the runway ready for takeoff.  Trim left untouched in the middle of the green band.  Takeoff was NOT normal (stuck to runway until about 120kts).

Start on the runway ready for takeoff. Trim adjusted to approx middle of the green band. Takeoff was normal (no sticking).

 

After this I deleted and reinstalled the CJ4.  I'll try some more flights tomorrow and report back.

 

 

[RandallR 446]

I have deleted and reinstalled this aircraft twice.  The first time (after reinstalling) she rotated normally and took lifted off at VR with no issues.  About 8 flights later she was sticking again.

I reinstalled again - this time, she continued to stick (including today).  Very frustrating.  All other portions of flight response are wonderful.  Right now the problem appears about 50% of the time.  For now, when I pull back and the nose doesn't rise, I immediately maintain back pressure and steer carefully - when the nose finally comes up (which can happen quickly) I immediately release a little back pressure to stay out of stall.  She flies smoothly after that.

On the times that she rotates normally I simply adjust trim to hold the proper climb angle and everything is fine.