Problems trimming the Crow! Taranis / Esoar / Xplorer2

[andyharrold 56]

Hi, I have an Xplorer2 which I fly with a Taranis and the ESoar template.

I am happy with the way it flies apart from taking Crow. I have found it to be very pitchy, nose up. I have altered the curve for the Elevator compensation to give me more nose down as soon as crow is selected ( full down!). This helps with the inital pitch but due to the large amount s of elevator comp when I stow them for landing am now encountering a pitch ( up, I think)  at low altitude. I have tried increased aileron. I have flown f3f models in the past and they have been easily trimmed to be benign regarding this pitch. I have also seen videos of f5j pilots slamming full crow and catching their models. Well you couldn't do that with mine!!!

I believe the CG to be correct, both by measurement and dive test. ( Could possibly come back a few mm)

I have spoken to Peter Mitchell, the original owner, and Gary B, who have both given me some options to try. ( Peter suggested trying a lot less aileron. ). Unfortunately due to the current situation I am unable to get out there and experiment.  Gary has kindly agreed to help me once the pandemic is over and it warms up a bit but I would like to get it a bit nearer to the sweet spot if I can before then , so that I can start to nail these landings!

So....Is there anyone on the forum flying an X2 ? If so, please could you give me some idea of how much flap and aileron and ele comp you are using and ideally, if you are using the esoar, what your ele comp curve looks like.

many thanks,

andy

[satinet 786]

I've had an X2. Lost it due to Frsky bit that's another story. I don't remember it being difficult to setup to land.

Sometimes you can suffer from the servos taking their time to get to full travel. If you think the elevator only has to go a few mm and the flaps can take a lot longer and the ailerons somewhere between. 

That being said most models need a curve on the elevator where it ramps up more quickly than linear and flattens off as you get to full flap travel.

 

[Phil.Taylor 878]

If its any help - I use very little up aileron for crow - maybe 10-15 degrees. 

Phil.

[SteveH 47]

If it helps most pilots I know now are using no up aileron at all during braking preferring to have maximum aileron movement / control on the landing approach.

The Shellim Esoaring programme is really great but have a look in the flight modes screen. It will programme a delay in the rate of flap deployment which can screw things up a bit. I have reduced mine to zero which suits me better.

[f3fman 274]

We all do something different !   I use a lot of up aileron, maybe only leaving 10% extra for aileron at maximum crow setting.... but ....  I am changing the crow setting a lot whilst landing and probably never very long at maximum crow  :-)

[rc-soar 442]

Got your PM Andy.

The fade times are set in the flight modes menu, the ones to look at are Landing and Power modes.

Just to recap the adjustments affecting compensation:

• Calibration (CAL mode) - sets the elevator limits
• Throttle trim - compensation adjuster. Range of adjustment is 0 - GVar3('Cmp')
• Curve2 ('CrC') - compensation curve

For my F3F setups, I mix in a fair bit of up aileron. The curve typically starts steep, flattens out, then steepens again for the last bit of crow.

[andyharrold 56]

Thanks for your help. I have adjusted the fade in/ fade out.

[Gary B 181]

One basic thing to check is that the elevator servo is neutral (horn 90° to the servo, no subtrim) with the tailplane neutral. I have one used glider that couldn't flare for landing properly because there wasn't enough up travel. It had been put together in a hurry to be ready for a competition. The fix was to pop the glued elevator servo and move it aft slightly without disturbing the linkage.  

Also check that there is full range of movement (AMT drive pin able to hit both ends of the fin slots before the end points of the servo are reached), there have been cases of the tail bellcrank fouling internally (sometimes on the balsa rudder post).

How long is your elevator servo horn and what hole is the clevis in? All variables that can stack up to give strange results.

Another used glider had the elevator servo horn slip during a winch launch, the horn and servo were different manufacturers, different spline/shaft diameters. The only thing holding it was the screw. It was almost impossible to fly, the competition slot turned into a 'get it down in one piece' mission.

You should aim for too much movement initially then move the clevis on the servo in a hole or two for better resolution (trim steps) but still giving enough travel for full control (crow compensation is the down limit and enough to stall/spin for the up travel).

I've just had a look at my Xplorer 1 F3J X tail fuselage, I guess the tail bellcrank  is the same. Both clevises are 12 mm from the servo axis, I've not flown this particular fuselage but have every reason to believe it's set up nicely (;-).

Not long till we can get out again hopefully.