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Old Dec 21, 2003, 07:26 AM
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sydney
Joined Apr 2001
22 Posts
first take off, but my corona kept spinning clockwise

Hi all,

I'm new to helis, but after reading so many great reviews and viewing the movie files from liteMachines I bit the bullet and got myself one!

To cut the story short, after following the helpful hints in rcgroups.com (Thanks all) I've finally finished it. Into the garage I went to try a little air hopping and to my surprise It started to spin clockwise even before it got off the ground (I've got trainers at the moment).

I've got the stock corona, with the futaba gy240 mounted on the shelf I built just behind the rotor and the wires exiting the box towards the TR. After reading some articles relating to spinning I tried one of the suggestions to put the gyro to normal (not reversed)...I looked but it's already in Normal pos.

After much tinkering and making sure the TR isn't slipping I tried putting the AVCS to "on", the DIR to "rev", and Gain to 75-80% ... and that seem to cure it...I hope.

My question is, is this the right setting to do? I read that having the DIR on rev will cause it spin.

Since majority of you members out there have a similar setup what setting do you have on your gy240?

Anyway, I was so excited, and at the same time very nervous on my first little hover ... mind you it only lasted for 5 seconds but it was getting too close to my garage wall! Cant wait to get to open land!

Oh yeah ... I got one boom strike after dumping the throttle too quickly, I heard a snap and saw some peices of wood fly off .. lucky it was only the balsa wood I taped on the boom! phew... thank you rcgroup for that little hint!

anyway .. gotta sleep .. work tomorrow.

Happy flying all.
Vic
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Old Dec 21, 2003, 08:20 AM
Hooked Heli Human
gmaster's Avatar
Western NC
Joined Dec 2002
1,556 Posts
first off.. something isnt right here.. either the TR is slipping on the wire.. either up front or at the back.. or.. you dont have the TR trim setup right.. it should have enough pitch so when you spin up and lift off its counteracting the spin of the blades.. without heading hold on...

try this.. try to trim using your Tx the TR until when you start to lift off it doesnt spin.. if you can do that.. then shut down.. go back and physically trim it yourself by turning some clevis' and then set your Tx trim back to zero... once you get it to take off without the spin.. when you put heading hold on its going to act like a total different helicopter.. it will make hovering so easy..

Good Luck
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Last edited by gmaster; Dec 21, 2003 at 08:23 AM.
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Old Dec 21, 2003, 02:54 PM
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sydney
Joined Apr 2001
22 Posts
Thanks for the info, will try it when I get home.

So I guess I have to put the DIR back to normal right?

I don't really know what is involved with trimming, I've been at this on my own and only have rcgroups.com for help

I'll let you know how it goes.

Vic
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Old Dec 21, 2003, 03:27 PM
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Ben74's Avatar
San Francisco, CA, USA
Joined Jun 2001
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hold on now. if you switched the gyro direction and it doesn't spin now, leave it there. you have solved the problem already.
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Old Dec 21, 2003, 03:42 PM
Hooked Heli Human
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Western NC
Joined Dec 2002
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Ben74 is right... i re-read what you said.. and i thought u meant you didnt get it to work and you 'hoped' you did.. if you have it setup now where it doesnt spin then you should be ok.. minor trim might work out to where you dont need that much adjustment.. give it another try and see what happens.. leave it set to rev..
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Old Dec 21, 2003, 07:35 PM
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Hong Kong
Joined Nov 2002
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Steps for Tail Setup

This is how I setup my tail to maiden my helis. This is for a Futaba GY240 or any AVCS gyro that has manual adjustments on the Gyro. For the GY401 or higher, you'll need to read the manual on setting up for AVCS mode. Non-AVCS setup should still be the same.

1. Gyro on NON-AVCS mode, 50% setting.
2. Plug in the battery to the heli, with the main rotor OFF, manually jerk the tail from side to side. The gyro should move the tail pitch in response to your movement and then centre the tail pitch when the motion stops. Check that the direction of the pitch compensation is correct. If it is not, then change the direction on the Gyro to "reverse".
3. Center the rudder stick on the tx and unplug the battery. Manually adjust the push rod length until the pitch of the tail rotor is as close to 0 degree as you can get.
4. Stand back and start up the main rotor. Increase the throttle until the heli is in a hover but BE PREPARED to compensate for any slight left or right tail rotation. Trim with trim tab until tail is neutral. Land and shut down the main rotor.
5. Take a close look at the pitch angle of tail rotor and memorise it. Move the trim tab on your tx to center, and unplug the battery. Manually adjust the push rod length until the pitch of the tail blade is at the same angle as when you have the trims set for the tail to be neutral.
6. Plug in battery and go to hover. If there is still trimming required, repeat Step 5 until you are satisfied. Land and unplug battery.
7. Turn on AVCS. If you have a GY240, set it at around 50%. Plug in battery and go to a hover. If the tail "hunts", i.e. wags back and forth, then land and reduce the gyro setting a little bit. Repeat until tail is stable. If the tail DOESN'T wag at 50%, then land and increase the setting until it starts wagging, then reduce it slightly until it is stable and you are done. The aim here is to use the maximum % AVCS setting with the gyro that is stable.

Hope this helps!
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Old Dec 21, 2003, 10:50 PM
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sydney
Joined Apr 2001
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Thanks Greg, that explanation really is clear! I've been looking everywhere for a post like yours.

I'll try it as soon as I get home.

Cant wait to try.

Vic
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Old Dec 22, 2003, 01:07 AM
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San Francisco, CA, USA
Joined Jun 2001
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btw, you should never ever apply trim while the gyro is in head hold mode. it will interpret the trim as constant stick input, causing the tail to slowly drift.
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Old Dec 22, 2003, 02:29 AM
Our Daddy and Heli Junkie
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In Heli Wonderland
Joined Aug 1999
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On the 240, if you do use the trim after you run it up. Just move the (rudder) stick to both extreems very fast 2-3 times. That will reset the center.
Oh, and don't do that while you are flying!!
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Old Dec 22, 2003, 02:22 PM
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sydney
Joined Apr 2001
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I've flown it again last night, following the steps GregW has advised.

I ended up with trimming it full left...strange. Put the trim back to the middle and had a look at the servo, it has somehow gone to a - 10 degrees angle instead of the 10 degrees.

Anyway, I'll try it again as my testing happened very late at night and the battery wouldn't cool down quick enough for another testflight.

I did hover for a bit longer though, can't wait for it to be trimmed.

Will keep you all posted.

thanks
vic
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Old Dec 22, 2003, 07:09 PM
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Hong Kong
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Quote:
Originally posted by vic2001
I ended up with trimming it full left...strange. Put the trim back to the middle and had a look at the servo, it has somehow gone to a - 10 degrees angle instead of the 10 degrees.
Hi Vic,

Not too sure what you mean by this... If this means that the servo arm has moved from +10 to -10 degrees after the flight, and with the same stick position and middle trim, this could mean that there is a problem with the servo gears.. Without trim, the servo arm should always return to the same place when the stick is in the middle.

In my experience, if hovering after setting the tail pitch to 0 degrees as I've describe, usually means trimming it at the very most, half way either left or right, never using up the full trim settings..

Greg
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Old Dec 23, 2003, 04:23 AM
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sydney
Joined Apr 2001
22 Posts
Greg,

I put the servo arm back to the +10 degrees (or if you are looking straight at it roughly at 1 oclock.)

I've checked the servo gears but I believe they are good.

Today I flew the heli with the hacker and hacker 40-3p heli - that throttle is a little touchy at around 30-40 percent isn't it.

I managed to trim the heading pretty well! thanks for the tips.

Now to get that drift to the right corrected. I took the trainers off and balanced them and to my dismay they are heavy on the right side. I've balanced them now and will attempt again later on.

Since I'm new to the hacker setup, I'm a little weary about plugging on the batts. The manual that came with it was pretty poor so I couldn't make out wether I am doing the right thing or Im endangering myself.

I turn on my tx, plug the battery, put the switch to the red mark, a beep is heard followed by a long pause and some more beeps.

When is the craft actually "armed"? as soon as I switch it on? (I know it's a silly question, sorry, but I have to make sure)

thanks
Vic
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Old Dec 23, 2003, 09:05 AM
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Hong Kong
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Hi Vic,

Looks like you're getting it trimmed..

I don't have a Hacker ESC, so I won't be able to help you with the start up sequence.. I'm sure someone else here will chip in with the correct info though..

If the throttle is touchy, then you can change the throttle curve to reduce the sensitivity around the middle, e.g. instead of a straight curve such as 0%, 25%, 50%, 75%, 100%, you can set it up as 0%, 35%, 50%, 65%, 100%. For safety, you should program your throttle cut switch.. What transmitter are you using?

Do you have a heli transmitter? i.e. no "clicks" on the throttle? If it has "clicks", then it will be much much harder to hold the heli in a hover. You can easily get rid of the "clicks" by opening up the transmitter and turning the metal strip around so that the notch is pointed away from the transmitter stick..

Greg
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Old Dec 23, 2003, 03:03 PM
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sydney
Joined Apr 2001
22 Posts
Greg,

I've got a Hitec Prism 7, it's not a heli specific one unfortunately. I'll see if I can change the sensitivity of the throttle. I think it's only got one setting though.

I've not thought about taking the notches off but that's a good idea. The throttle stickyness I think is to do with the soft start of the ESC. I've not had a problem with the fusion stock but I'll get used to it.

Last night I balanced the trainer, put it back on the heli and still it slides right. However I do believe I found the culprit...the battery. It weighs one side of the chopper down a little.

What do you guys do to counter this?

vic
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Old Dec 23, 2003, 05:27 PM
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Hong Kong
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Due to the design of the Corona, the right side will be slightly heavier than the left due to the battery pack.. You'll need to dial in some left trim on your aileron to counter that.. Unless you want to upgrade to the Voyager E landing gear, which will then allow you to put your battery between the landing gear..

I have mine in the normal position, but since I'm using Lipoly, it's lighter and has less of an impact on the left/right balance.

You definitely need to get rid of the "clicks".. You will instantly become a much better flyer when you do that..

Greg
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