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Old 10-18-2007 | 02:08 PM
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Rafael23cc
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From: Junction City, KS
Default RE: T-rex and JR 8103 Dt programming

I don't mean to sound disrespectful or harsh, I'm trying to look at this thread in a critical manner so we all can learn. This is the purpose of this thread and the purpose of all forums, right?

So correct me if I'm wrong, if all you did was cut and paste from the manual, what is the purpose of the thread? Wasn't this already published information?

All what I'm trying to say is that, if you are going to cut and paste information here, you should add some "meat" to the subject. The "meat" being the logic behind the numbers. Nut just a recipe for programming that might not be what I'm looking for.

So this is how I actually set up my helicopters.
After I do the system settings as indicated above...
1. Install the servos and check which arm on the servo wheel is closest to having perfect alingment.
2. Use subtrim to make the alingment perfect.
3. Make sure the tavel adjust is 100% ON ALL CHANNELS
4. Go to the Swash menu and enter the desired mixing. Probably already published on the manual.
5. Set the collective pitch "window" on the swash menu. Adjust links as necessary to obtain desired range. For aerobatics and 3D 0 degrees should correspond with mid-stick (50%) travel on the pitch/throttle stick.
6. check that the cyclic pitch is approx 7 degrees on aileron and elevator. Increase or decrease the swash menu numbers as necessary. If a servo does not move in the desired direction, a combination of servo reverse or a negative number on the swash menu should have it moving in the correct direction. If there is any binding after the deflection is set to 7 degrees, there is an error in the assembly and links need to be adjusted. After 17 degrees of total pitch (10 degs of collective pitch and 7 degs of cyclic) the blades enter a stall where the airflow starts separating from the blade surface.
a. Make the collective pitch be 0 degrees
b. Move the blades on line with the tailboom.
c. Check Aileron deflection by moving the stick to the extreme and measure (both ways) if the deflection is not the same, there are some links that need adjusting.
d. move the blades so that the flybar is on top of the boom and check the elevator deflection as indicated above.
7. Depending on the gyro, the travel needs to be the maximum allowed by the mechanical set-up of the machine. You want the blades to have a slight angle to counteract the normal torque of the motor while hovering. From there, check for gyro sensing by grabbing the helicopter and making it rotate on the main shaft. If the gyro reacts incorrectly, reverse the sensor. Gain will be adjusted at the field. True center of the gyro and servo will be adjusted at the field too. At the field, set the gyro in rate mode and hover the helicopter if the tail drifts, adjust the length of the control rod until the drift is gone. Make sure the servo is still centered. The gain is adjusted to eliminate drift after the control rod has been adjusted.
8. Set the throttle curve at the field, with a head tachometer. You are looking for a headspeed that will make the heli feel crisp, but will not drain your batteries too fast. Also, the batteries should not feel hot after a normal flight. If they are hot, your headspeed is too high. Normally 2400rpm for a Trex 450 is good enough. Some people prefer higher headspeeds. Set the hovering HS and then adjust the points above the hovering point by "punching" the heli up and listening for the motor noise.

Those are the basic steps I take when setting up a new heli. I think I have not missed any. Then again there are the Finless videos in Helifreak that take you step by step almost exactly like I did above. He does it for a Trex, but the theory is the same.

Rafael