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Old 10-05-2010, 11:32 AM   #1 (permalink)
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Default Rate vs heading hold? Trim? Help!

I'm a noob just getting into FF, and up to now have been using HH only. I tried using Rate for the first time, and needed to feed in about 7 clicks of trim. Then after switching back to HH, I had to trim it back the other way.

I know I'm doing something wrong in the setup, but I don't know what. I've tried searching the forums and I can't figure out what I need to do.

Gyro is an Align 780 and it's a Trex 450 Sport (combo kit with all stock electronics).

Also, do I understand correctly that Rate mode will allow the tail to track the direction of flight?

Thanks for any insight! I've learned SO much from lurking here.
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Old 10-05-2010, 11:50 AM   #2 (permalink)
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In order to fly in rate mode, you tail needs to be mechanically trimmed for center.

To do this, take off, switch to rate, note the drift, land, shut down heli, and adjust the linkage or move your tail servo on the boom.

Repeat until you have no drift in rate mode. Now since you didn't adjust the trim on your Tx, you should have it trimmed the same in rate and heading hold modes. Once trimmed correctly, your tail servo arm will still be at 90 degrees, but your tail slider will be off to one side slightly while your tail blades have about 8 degrees of pitch to counter act the torque generated by the motor.

And yes, rate will allow the tail to 'follow' the heli around more when flying fast. The heli will also weather vain into the wind during a hover, which you have to be mindful of when you are setting the trim.

The old school of thought was to trim the gyro in rate mode to get the best performance. Often beginners first learning FF would fly in rate mode. Now days, I see more and more people skipping rate mode all together, people have their tail setup so the slider is in the middle (not trimmed mechanically), and simply fly in HH mode all the time.
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Old 10-05-2010, 12:14 PM   #3 (permalink)
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Short and sweet....

HH requires 0 trim. Period. In order to be able to go into rate mode, you need it set mechanically at roughly 7 or 8 degrees IIRC. You should never 'trim' your tail. Why fly rate mode? I don't even have my heli setup for it.....
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Old 10-05-2010, 01:01 PM   #4 (permalink)
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I tried rate mode once when learning to hover, but did not like it. I learned to make nice carving turns using HH mode as a result. I'm so used to banked turns with HH that it is second nature. I think most people pick up this skill when learning FF.
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Old 10-05-2010, 01:08 PM   #5 (permalink)
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I've been told to alwasy setup in rate mode...

As to how...one thing you don't want to do is to be in the air and switch between rate and HH...less you are good enough to control the tail shift. Depending on setup it can be a slow drift or may push the tail quite quickly.

What I do is initialize in HH then switch when as I spool up. As I'm spooling up, I'll see the tail pushing one way or the other....I adjust trim to compensate till it's holding. I keep adjusting trim til I can hold a hover in rate mode. Then I land, spool down, power down then restart the bird in HH. Now HH and rate mode will be the same....I'll test here

Then if that's acceptable, I'll power down the adjust the tail, mechanically till I remove the trim. (I mark wher the pitch slider is then remove the trim and either adjust links or move the servo on the boom)

I found that sometimes I like rate and sometimes I like HH. I like rate when I'm just flying around, no tricks...but like HH if I'm doing flips, rolls etc.
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Old 10-05-2010, 02:47 PM   #6 (permalink)
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only thing i use rate mode for is setting up my tail electronics, once i am done doing that i always fly in HH. rate has it's advantages witch is really only one and has quite a few disadvantages IMO HH has no disadvantages and you learn how to fly the tail when you turn
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Old 10-05-2010, 06:51 PM   #7 (permalink)
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With a gy401, after you trim for rate mode, you simply cycle back and forth from avcs, to rate mode a few times and it's resets your trimmed position to center stick for HH mode.

I believe you can also trim in rate mode, then power down, then repower in HH and it will sense your now trimmed position as zero, or center stick. This freely allows you to switch between avcs, and rate mode on the fly depending on your flying style.

I believe this such procedure is pretty standard for all gyros that incorporate hh and rate modes. Check the manual.

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Old 10-05-2010, 07:21 PM   #8 (permalink)
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Lot of varying information here ... but my observations are:

1) You can either use a mechanical tail setup for rate mode, or just use sub-trim on the radio. I prefer sub-trim option.
2) Make sure to reset the travel limit on the gyro after.
3) The HH neutral (center stick) position will be set on power-up for the GY401, or you can toggle the gain between rate mode/HH 3 times in 1 second. If the gyro starts before the rx/tx connection, then very likely you have to toggle the gyro gain to reset neutral.
4) If you never fly rate mode, then you can leave the default tail pitch to 0 (I could not tell any difference when flying, maybe just me though)
5) In HH mode, never add trim after you set the neutral signal position. If the heli is yawing left or right in HH mode, that means there is some vibration throwing off the gyro. Check blade balance, shafts, etc ...
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