Tilt issue - HeliFreak
Fun, Learning, Friendship and Mutual Respect START  HERE


Unregistered
Go Back   HeliFreak > R/C Helicopter Support > 600 Class Electric Helicopters


600 Class Electric Helicopters 600 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


Reply
 
LinkBack Thread Tools Display Modes
Old 04-13-2011, 07:35 AM   #1 (permalink)
Registered Users
 

Join Date: Sep 2010
Location: Vancouver, BC
Question Tilt issue

Everything is perfectly level (swashplate etc).

When I attempted a trial hover... just as I was about to lift off the ground I noticed the heli was going to tilt off dramatically to the left side. So I quickly reduced power.

The only thing I could find a tad off was one rotor measured 1/2 degree difference in pitch than the other. So I adjusted one link and that fixed the pitch difference.

Could that have been the cause or would it be something else?

I haven't had a chance to do another spin test... I live in Canada and it went from +15 down to +3 today. So I guess an attempt is out of the question until it warms up a bit.

Last edited by Bots; 04-13-2011 at 01:46 PM..
Bots is offline        Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 04-13-2011, 09:16 AM   #2 (permalink)
Registered Users
 

Join Date: Dec 2009
Location: American Fork
Default

Have you fully checked the swash movement without the blades spinning? Most bad tilt issues I've seen are because one of the servo directions isn't right in the CCPM mixing or something.
__________________
Trex 550e FBL BeastX, Trex 450 se v2, Blade mCPx
And lots of those funny things with wings and a prop on the front instead of the top.
mulicheng is offline        Reply With Quote Quick reply to this message
Old 04-13-2011, 10:33 AM   #3 (permalink)
Registered Users
 

Join Date: Dec 2010
Location: NJ
Default

Your helicopter will naturally want to tilt to the right, here is why.
The helicopter hanges on its rotor head and produces torque in the opposite direction. To counter this torque, we use a tail rotor. Unfurtunitly, the tail rotor is mounted below the head and pushes to the helicopter to the left. The helicopter hanges on the head and the tail rotor is pushing to the left below the head causing the helicopter to tilt to the right. The only way to counter this effect is to move the tail rotor up into the same plane as the rotor head. Here is another way to look at it. Look directly down the tail boom. The tail rotor looks like it is mounted to the side of the helicopter below the rotor head pushing to the left causing the helicopter to tilt to the right. I hope this helps.

SJW
stephenwagner is offline        Reply With Quote Quick reply to this message
Old 04-13-2011, 12:02 PM   #4 (permalink)
Registered Users
 

Join Date: May 2009
Location: England
Default

If this is an FBL bird, then, yes, the vibrations induced by the out-of-track blades might be enough, particularly on a resonating surface, to get the aileron sensor to freak out.
ollie2893 is offline        Reply With Quote Quick reply to this message
Old 04-13-2011, 12:11 PM   #5 (permalink)
Registered Users
Thread Starter Thread Starter
 

Join Date: Sep 2010
Location: Vancouver, BC
Default

Quote:
Originally Posted by ollie2893 View Post
If this is an FBL bird, then, yes, the vibrations induced by the out-of-track blades might be enough, particularly on a resonating surface, to get the aileron sensor to freak out.
Nope, it has a fly bar.

I took the head off and used the swash plate leveler... again. I notice aileron, and pitch subtrim off by a hairs width at full pitch but couldn't iron it out. So what I did was transfer the hairs breath difference to the elevator. This is as close as I can get. Now at low, mid, and high pitch all is well... except at 3/4 pitch the elevator subtrim is now off by just a hairs width.

Hmmm. can't get it any closer. Is this normal?
Bots is offline        Reply With Quote Quick reply to this message
Old 04-13-2011, 01:43 PM   #6 (permalink)
Registered Users
 

Join Date: Dec 2009
Location: American Fork
Default

Well, you said dramatically.. so I'd say no. But then again, it sounds to me like perhaps you haven't done this a lot.. or you wouldn't be asking if it's normal. You'll have to provide more clarification I guess.

As pointed out... all helis will slide a bit because of the tail but I wouldn't say it's "dramatic". A tiny bit of cyclic input on my takeoffs keeps them where I want them.
__________________
Trex 550e FBL BeastX, Trex 450 se v2, Blade mCPx
And lots of those funny things with wings and a prop on the front instead of the top.
mulicheng is offline        Reply With Quote Quick reply to this message
Old 04-13-2011, 01:46 PM   #7 (permalink)
Registered Users
Thread Starter Thread Starter
 

Join Date: Sep 2010
Location: Vancouver, BC
Default

Actually it wanted to tilt to the left... sorry I should have clarified. Will change in the original post.
Bots is offline        Reply With Quote Quick reply to this message
Old 04-13-2011, 07:03 PM   #8 (permalink)
Registered Users
 

Join Date: May 2009
Location: England
Default

Helicopters are unconditionally unstable machines. They will do any manner of things unless proficiently controlled. Simply use the trim tabs to counter any bias to tilt left out of a hover. And let us know how much trim you needed in the end.
ollie2893 is offline        Reply With Quote Quick reply to this message
Old 04-14-2011, 07:46 AM   #9 (permalink)
Registered Users
 
Posts: 3,485
 

Join Date: Jan 2010
Location: Hoorn (NL)
Default

Quote:
Originally Posted by ollie2893 View Post
Helicopters are unconditionally unstable machines. They will do any manner of things unless proficiently controlled. Simply use the trim tabs to counter any bias to tilt left out of a hover. And let us know how much trim you needed in the end.

Trim Dont do that. make sure the swash is level, the CG is good, and the blade pitches are the same.... if 1 of these is off, fix them instead of trim the problem away.
__________________
Designing/Building the HEX Helicopters
Sponsored by Gens Ace Batteries, Gryphon Rotorblades, RCbearings.co.uk,
Nko15 is offline        Reply With Quote Quick reply to this message
Old 04-14-2011, 07:54 AM   #10 (permalink)
Registered Users
Thread Starter Thread Starter
 

Join Date: Sep 2010
Location: Vancouver, BC
Default

Quote:
Originally Posted by Nko15 View Post
Trim Dont do that. make sure the swash is level, the CG is good, and the blade pitches are the same.... if 1 of these is off, fix them instead of trim the problem away.
Ok thanks for the advice.

WRT the swashplate... it is as close to perfect as I can get it. (See above)

The pitch is now perfect.

I'll be checking the CG soon.

Super!
Bots is offline        Reply With Quote Quick reply to this message
Old 04-14-2011, 08:46 AM   #11 (permalink)
Registered Users
 

Join Date: May 2009
Location: England
Default

Quote:
Originally Posted by Nko15 View Post
Trim Dont do that. make sure the swash is level
Read what the OP writes first before you criticize others !! He has triple-checked his swash, he says. Now what... ?!?

Trim it out in a hover and tell us how much trim you needed. I don't have any sense for your flying skills. I don't even understand whether your tilt is persistent or merely a ground effect phenomenon.

I am sure, though, that CoG will be the least of your concerns. In fact, I wonder how many here have ever balanced their CoG across aileron? (Unless you have your battery attached to the lhs only or fly a X-trainer)
ollie2893 is offline        Reply With Quote Quick reply to this message
Reply

Tags
pitch, spin, test, tilt




Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the HeliFreak forums, you must first register.
Please enter your desired user name, your REAL and WORKING email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself. Use a real email address or you will not be granted access to the site. Thank you.
Email Address:
Location
Where do you live? ie: Country, State, City or General Geographic Location please.
Name and Lastname
Enter name and last name here. (This information is not shown to the general public. Optional)
Helicopter #1
Enter Helicopter #1 type and equipment.
Insurance
Please select your insurance company (Optional)
Helicopter #2
Enter Helicopter #2 type and equipment.
Helicopter #3
Enter Helicopter #3 type and equipment.
Helicopter #4
Enter Helicopter #4 type and equipment.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On




Copyright © Website Acquisitions Inc. All rights reserved.
 

SEO by vBSEO 3.6.1