Question about run-up time when setting up DDVP

hello? Everyone.
Currently, a motor is mounted on the tail of an electric helicopter and set to DDVP for a flight test.
I have a problem and I have a question.
While the helicopter’s main rotor is running, the tail motor rotates at a high speed. Is there any way to adjust the tail’s run-up time?
If the tail motor rotates quickly before takeoff, a load is applied to the motor and the motor burns out.
Please let me know how I can solve it.
The current firmware version is 4.1.5.
Thank you in advance.

@retromix if you could post a log, that would be great. At a minimum please post your parameter file.

Thank you for answer.
Sorry for uploading the flight log late.
Last flight log.
Please analyze what the problem is.
Thank you.

@retromix please give me access to the file. It says the file wasn’t shared with me

I have turned off the sharing permission so that everyone can see it.
Resend the link.
Thank you.

@retromix So it appears the code is responding correctly to your setup. What type of ESCs are you using for the main and tail rotor motors? Are you using the governor of these ESCs or just setting speed by the setpoint?
Here is the plot of the Main and tail RSC output. It increases the PWM over the 9 second H_RSC_RAMP_TIME. Now it appears that you had the SERVO7_MIN set low initially and then raised it to 1100. You also experimented with the SERVO7_MAX.

I need to understand what problem you are having.

It appears that you changed the SERVO7_MAX which should have affect the tail rotor speed. Why do you feel you need to adjust the run up time

Why does the tail motor rotate quickly before takeoff? Is it not spinning when the main rotor is spinning? Do you have the log from when you had this issue?

Thank you for answer.
For the main motor, Hobbywing 200A ESC was used.
For the tail motor, T-motor 70A ESC was used.
The ESC of the main motor used a built-in governor,
The ESC of the tail motor is a type without a governor.
As the main rotor spools up, the tail motor rotates quickly before rotating.

The log file I sent you now is the log file with the problem.

@retromix I am not sure I can fix your problem. When you arm with the servo7_min at 1100 does the tail motor start spinning?

Part of the problem is the esc with the governor is expecting the setpoint right away where you need to gradually start the tail esc. So having the long ramp time is good for the tail esc but not good for the main rotor esc. The only suggestion is to make the ramp larger. Unfortunately the tail rotor rsc does not have separate control parameters.

After setting servo7_min 1100 and arming, raise the throttle stick to start the tail motor.

I’ll try it with a bigger ramp as you suggested.
We will inform you of the results after testing.
thank you.

What do you mean when you say that you raise the throttle stick to start the tail motor? You should enable motor interlock and the tail motor should start with the main motor. It should have nothing to do with the throttle stick (collective).

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Bill, I have used on all my 3 Helis tail motors - DDVP over the years.
All 3 Heli ESC were from CASTLE Front and Rear ( different models ) and used always the ESC internal governors. I must say that I never had a single problem. The ESC were starting up together slowly ( my setup ) and never failed. Castle had the best Governors at that time period. That’s all I can say. Retromix - needs a ESC for the tail with internal Governor in my opinion. As you know I have stopped flying Helis and also have only the JetRanger (Align 700 E inside) left on the shelf.
BTW. Great info at the conference from you the other day. Regards Fred

Thanks for your response. I figured that it would work better with both ESCs having internal governors.


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