motor bogging

[tonydig11]

I got my 250 all set up. and flying great. only thing is that my motor bogs when trying pitch pumps. its really bad when i do a high hover and sink with negative pitch then try to pump to full pitch. the heli takes about 7-10 feet to transition from negative to positive pitch.

im running sky lipos 30c 800 packs
90% flat curve
-12 and +12 pitchs

any advice heli is 100% stock

[jreue]

I'm having a similar, if not the same issue. My collective seems delayed by a fraction of a second. It does not seem to have the same 'pop' as it use to.

The following was tested:

• With absolutely ZERO wind.
• Tested both in both Non-IdleUp and IdleUp modes

Results:

• Hovering at 6', I can pitch pump, and there is a slight delay before the heli ascends.
• Most of the time, when coming out of a turn, I drop in altitude alot, and I have to give almost full collective to get it from touching the ground.

Anyone have any ideas?

[birch]

How tight is your gear mesh?

[jreue]

I check tonight and report back.

[janol]

ball links at the blade grips are loose?

[dbennettya]

Mine reacts almost instaneously, however if you have a fast sink rate it does have a slight delay due to having to kill the downward velocity and start positive ascent.

Make sure all ball links are silky smooth. I use a MH ball link sizer and it works great. You can easily test by lightly trying to rotate the ball links back and forth a little, they should move freely with no drag.

BTW, I run +/-11* per the manual and have plenty of collective pop. I do run slightly higher and different throttle curves than recommended. N 0,35,70,85,100 ST-1 100,85,70,85,100 and ST-2 100s.

Good Luck, Don

[Ah Clem]

If you run it at a flat 90%, of course it will bog.

When you increase the load on the motor by adding collective or cyclic, but do not increase the throttle, it will bog.

This is why so many run governors, so that the throttle is constantly adjusted to the load imposed by the head (and tail).

This is with gentle "U" shaped throttle curves and cyclic to throttle mixing-listen to the RPM:

http://youtu.be/NS4CvMsl19I

When the collective increases, the throttle increases. When cyclic is added the throttle increases.

A high quality governor is the best choice, when available.

[tonydig11]

Originally Posted by Ah Clem

If you run it at a flat 90%, of course it will bog.

When you increase the load on the motor by adding collective or cyclic, but do not increase the throttle, it will bog.

This is why so many run governors, so that the throttle is constantly adjusted to the load imposed by the head (and tail).

This is with gentle "U" shaped throttle curves and cyclic to throttle mixing-listen to the RPM:

http://youtu.be/NS4CvMsl19I

When the collective increases, the throttle increases. When cyclic is added the throttle increases.



A high quality governor is the best choice, when available.

thanks very much. i enjoyed your movie. i do run gov on my 550 but not my 250. how gentle of a U curve do you suggest i try out.

[Ah Clem]

About 100-90-100. If you have a JR or Spektrum radio (DX7 or above), set these three points and activate "EXP" in the Throttle curve menu. This will change the curve from a sharp "V" to a gentle "U" with only the three points.

Go into the P-Mixes and add 10 % Aileron to Throttle mixing and 10% Elevator to Throttle mixing (on JR/Spektrum radios you have to have the mixes set negative for on direction and positive for the other).

Check in the Monitor screen to see that the throttle increases as you move the Aileron stick both left and right and the Elevator up and down (if the mixes are set wrong and decrease the throttle as you add cyclic it will ruin your whole day).

I know on the 11X and 12X cyclic to Throttle mixing is built into the "Swash" menu and only has to be activated and the percentage added.

Very easy to do-the whole thing can be done in less than 10 minutes and the improvement is well worth it.

The goal is to get absolutely constant RPM.

By the way, the Trex 250 has a reputaton for having tail issues (wagging, blowouts, etc.). You can see the tail is quite solid in the video. Constant RPM helps a very great deal with this type of issue (as do the KBDD Tail Blades-sorry, I had to work a plug in there somehow).

Good luck to you sir!

[Sonic_BOOMER_SOONER]

You're always good for some great advice Ah_Clem. I'm going to try that on my 250 & 450!

[rctazz]

How much vertical play do you have on your main shaft? Even with the motor bogging, 7 to 10 feet to reverse direction is huge.

[tonydig11]

thanks for all the great advice.

I have no play in main shaft

[jreue]

Guys,

Went over the heli last night and here are my results.

• Main gear to pinion mesh seems fine/normal. Not too tight, not too loose.

• I went over the head, and all seems fine mechanically.

• I'm certain I'm at 0 pitch at mid-stick
• If I recall correctly, I am set up with -10 0 10 pitch.
  • I'll triple check this tonight.

• I checked all my linkages. None of them too tight or too loose. When rebuilding this heli, I tried very carefully to size them properly.

• I'm using the Align 'tapered' main blades that comes with the 250 kit
• 15T pinion
• KBDD tail rotors
• I'm using these EXI 250 paddles. Could this be an issue? They are shaped my differently from the stock Align paddles.

• Someone mentioned in another thread to bind to a new model. I went to the liberty of just resetting everything.
  • Using my DX6i, I cleared and made a new model
  • I entered in all my old values into the new model. The ones worth noting are
    • D/R Expo
      • AILE: 100%, +8
      • ELEV: 100%, +8
      • PITCH: 100%, +5
    • Swash Mix
      • AILE: -45
      • ELEV: -45
      • PITCH: +55

• • • T-Curve (Normal): 0 40 80 90 100
    • P-Curve (Normal): 35 42.5 50 75 100

• • • T-Curve (IdleUp): 95 90 80 90 95
    • P-Curve (IdleUp): 0 25 50 75 100
  • I rebound my heli to the new DX6i model

• Someone mentioned in another thread to reprogram the ESC. I'm not sure how to "reset" it, but I took note of what I'm currently running.
  • Brake: Disabled
  • Electronic Timing: Mid
  • Battery protection: High cutoff voltage protection
  • Aircraft: Helicopter 1 (Soft Start) (no governor)
  • Throttle Response: Quick
  • BEC Output: Need to check

[jreue]

I've spent some more time ensuring everything is correct on the head.

I found my pitch was >+12 0 -10 on both blades. Adjusting my Pitch setting in the Swash Mix from +55 to +60. This equalized it to +12 0 -12

I have yet to run a test flight on all my changes as it is way too late. Hopefully tomorrow I can get one in.

[Suburban92]

didnt read others replies but

Motor Timing on ESC will cause bogging..

[HelliYea]

Originally Posted by jreue

• • • T-Curve (IdleUp): 95 90 80 90 95
    • P-Curve (IdleUp): 0 25 50 75 100

That throttle curve is not V, more like a Y. I'd try 95, 90, 85, 90, 95

[jreue]

Nice catch! I'll definitely try that tonight!

[jreue]

Well, it looks like 'something' fixed it. I ran a test flight last night, and this thing now has lots of pop; it's back to how it use to be.

Thanks for all who suggested fixes!