3GX forward elevator movement on takeoff (250 DFC Pro)

[gazor]

Apologies if this has been answered elsewhere. I'm wondering if I've done anything obviously wrong to have severe forward pitching before getting off the ground (with a slow-ish spoolup).

I've just completed my build of the Align 250 Pro DFC Super Combo (paired with a DX8) and perhaps I need to do a better job of leveling the swash or something. It is setup as close to the manual as possible; I ended up with reversed gyro compensations for ail, ele in DIR setup mode (as well as for the rudder). The gyros appear to properly compensate nudges with opposite control movements.

I'm a little reluctant to build up head speed any faster due to the severity. I've checked the gyro compensation several times. The swash leveling certainly isn't perfect (within .2 degrees). In normal operation I do observe really severe cyclic servo throw well outside the values established in DIR mode (swash mix is-44 Ail, -44 Ele, -33 Pit) and via the software the limits are set to 40%.

Any thoughts? This is my first build in many years and I have probably done several things wrong.

[bad007]

.2 degrees? Used a digital gauge? The FBL gauge, rod and a manual gauge works better.
Setup your 0deg. pitch from one side and then spin the head 180 and check from the other side. If it doesn't read the same the swash isn't level. Do the same front to rear and for max pitch. Max pitch being different from side to side will cause drift, for example more on the left is like having back cyclic and it will drift backwards.
As for compensation by discription the swash should try to stay level when tipping the helli.
For PC and TC you need to have enough head speed for the FBl unit to stabulize before yout get light on the skids. for PC set to 40 45 50 75 100 and TC 0 60 80 ** ** 80 being the min at mid stick.
Review all the instructions and make sure you didn't miss anything.
43 in the swash gives ya 8 cyclic right and limits only 40? Limits are to be set to the point before binding. How much expo do you have and what about the flip and roll rates?

Originally Posted by gazor

Apologies if this has been answered elsewhere. I'm wondering if I've done anything obviously wrong to have severe forward pitching before getting off the ground (with a slow-ish spoolup).

I've just completed my build of the Align 250 Pro DFC Super Combo (paired with a DX8) and perhaps I need to do a better job of leveling the swash or something. It is setup as close to the manual as possible; I ended up with reversed gyro compensations for ail, ele in DIR setup mode (as well as for the rudder). The gyros appear to properly compensate nudges with opposite control movements.

I'm a little reluctant to build up head speed any faster due to the severity. I've checked the gyro compensation several times. The swash leveling certainly isn't perfect (within .2 degrees). In normal operation I do observe really severe cyclic servo throw well outside the values established in DIR mode (swash mix is-44 Ail, -44 Ele, -33 Pit) and via the software the limits are set to 40%.

Any thoughts? This is my first build in many years and I have probably done several things wrong.

[gazor]

I did use a digital gauge...unfortunately. I didn't have a rod to use but will pick one up and give swash leveling another go. It looks like there is a very small difference between left and right side pitch when folding the blades. I just didn't expect it to make such a difference, there's no way I can fully compensate with cyclic input.

I'm pretty sure gyro the compensation is correct.

My throttle/pitch curves are similar (Throttle: 0,37,63,84,100, Pitch: 30,36,50,75,100, Scale: 0,25,50,75,100). I'll bump them up a bit now.

-43 in the swash mix gave 8 cyclic when in DIR mode. In flight mode 40% limits does prevent binding but obviously a huge collective pitch throw.

I was running 20% expo and the flight mode flip rates are both 50% (probably a bit high?).

I'll follow up when I can level the swash better.

[bad007]

Originally Posted by gazor

I did use a digital gauge...unfortunately. I didn't have a rod to use but will pick one up and give swash leveling another go. It looks like there is a very small difference between left and right side pitch when folding the blades. I just didn't expect it to make such a difference, there's no way I can fully compensate with cyclic input.

I'm pretty sure gyro the compensation is correct.

My throttle/pitch curves are similar (Throttle: 0,37,63,84,100, Pitch: 30,36,50,75,100, Scale: 0,25,50,75,100). I'll bump them up a bit now.

-43 in the swash mix gave 8 cyclic when in DIR mode. In flight mode 40% limits does prevent binding but obviously a huge collective pitch throw.

I was running 20% expo and the flight mode flip rates are both 50% (probably a bit high?).

I'll follow up when I can level the swash better.

You mean 40% for limits gives a huge amount of cyclic right?
Ya lower the flips rates for maden, up expo to 30% so you don't have any supprises being to twitchy and get the 1/4 and 1/2 throttle up, that's to low.

[gazor]

Originally Posted by bad007

You mean 40% for limits gives a huge amount of cyclic right?
Ya lower the flips rates for maden, up expo to 30% so you don't have any supprises being to twitchy and get the 1/4 and 1/2 throttle up, that's to low.

Yep. Perhaps my DIR setup was completely off. Turns out that I have 22 degrees of cyclic throw in flight mode! I lowered all the flip rates, upped the throttle and expo. One other thing I hadn't done was setup reverse "Anti-torque compensation" in the rudder section of the software (though this doesn't appear to have changed the way the rudder reacts - though it was set up in the rudder setup).

Anyway, finally got it off the ground manually compensating for the huge forward movement. It actually seemed pretty solid when in the air. Super sensitive though (comparing to a 130X and a 550E 3GX). Blade tracking is clearly rather bad so I'll take a much more careful look at each blade.

Thanks for all your help.

[bad007]

Originally Posted by gazor

Yep. Perhaps my DIR setup was completely off. Turns out that I have 22 degrees of cyclic throw in flight mode! I lowered all the flip rates, upped the throttle and expo. One other thing I hadn't done was setup reverse "Anti-torque compensation" in the rudder section of the software (though this doesn't appear to have changed the way the rudder reacts - though it was set up in the rudder setup).

Anyway, finally got it off the ground manually compensating for the huge forward movement. It actually seemed pretty solid when in the air. Super sensitive though (comparing to a 130X and a 550E 3GX). Blade tracking is clearly rather bad so I'll take a much more careful look at each blade.

Thanks for all your help.

Anti-torque comp is ahead gain for when you add pitch fast so the tail doesn't blow out and it's set after the delay setting, green for the 3GX being mounted upright and red for upside down.
22 deg cyclic, indicates setup is off. You set 8 and then at stock limits you should get 12-13deg. out of setup default limits. You can set limits either linked up or running FM holding the rudder one way and then the set button to enter FM settings. Pre print the instructions ahead of time.
Tracking being off can cause tipping and just check both blades at the same point mid stick and at mix pitch and they should read the same.
Super sensitive cyclic lower flip and roll rates but go no lower then 50 and you can lower limits keeping track of cyclic pitch out of setup.