Fun, Learning, Friendship and Mutual Respect START  HERE


Unregistered
Go Back   HeliFreak > R/C Helicopter Support > 250 Class Electric Helicopters


250 Class Electric Helicopters 250 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


Like Tree1Likes
  • 1 Post By BobHyatt
Reply
 
LinkBack Thread Tools Display Modes
Old 07-02-2020, 08:36 PM   #1 (permalink)
Registered Users
 

Join Date: Apr 2020
Location: Birmingham, AL
Default align 300x swashplate fix

Jayrat and I have been discussing this issue. For those unaware, the swashplate-servo links have an issue. The back servo (elevator) is mounted lower than the other two, yet all 3 have the same sized linkage. You basically can't level the swashplate with servos at 90 degrees.

Here's what I did last night.

1. Removed the head/blades/DFC links...

2. Removed two front swashplate links from both the servo and swash. If you look, you can see that the link rods are threaded far enough that if you thread them all the way into a ball socket, it will punch into the interior or bulge the interior so that the link will pop off. Yet we need these two links to be as short as possible since the rear link is already 4-5mm too short.

3. Took dremel and ground 1-1.5mm off of each end of those two links. Which will shorten them by 2-3mm. Re-install and level the swash with the servos at exactly 90 degrees. Now it works.

4. Next problem is trying to get zero degrees pitch at the same point (servos at 90 degrees). Could never get there. Always had a +2 to +3 pitch at the zero point. So, I removed the DFC links and cut about 2mm off the end of each one (I measured the depth and it was about 3.8-3.9mm so I took one half of that.)

5. I then threaded the linkage rod into the DFC link and measured how far it was from burying the threads all the way inside. I ground off the link rod on the end this much. I think this was about 1-1.5mm. I then ground the same amount off the other end. Screwed the links into the DFC with some align locktite, and then threaded on a ball link for both.

6. Reassembled everything and checked pitch. woah. -4.5 to -5 at the neutral point. So I actually had to thread some of the DFC linkage out of the ball joint to get it up to zero (think it was 2-3 turns.

I now have servos centered, swash level, and zero (+/- 0.2) pitch.

Had to spend a few minutes playing with the pitch curve after all of this, but really like the way it behaves now. At 50% throttle heli sits on the skids. Used to almost fly.

This all took maybe an hour or so to do.

One other note. We had talked about the 200 skids from amazon. They offer a wider stance and a slightly better skid shape for flying off grass. But it is pretty hard to keep the tail rotor clear unless your grass is cut to ľ" high.

They provide some spacers and I took two of the shortest ones and put them on the screws on the back of the lg (between the cross mount and mounting point on heli). Gave it a little of that align "forward cant" which helps. Thing still does not like any taller grass, and Bermuda gives it fits since any skid will snag the way Bermuda runners grow. But landings and takeoffs are uneventful other than for the occasional cleaning grass particles off the damned tail rotor.

Other notes. You could probably reduce the amount you cut off of the DFC arm to 1mm, and trim the link rod to bottom out. If you feel a little antsy about going too far. What Align should do fits into two categories.

(1) provide a longer elevator link, enough to exactly offset its lower mounting point.

(2) very slightly raise the Jesus screw hole. Then you would not need to fiddle with cutting the DFC linkage at all. I came within an inch of doing this with my drill press. Drill a new hole at 90 degrees to the existing hole, maybe 2-3mm higher. Chamfer to make it easier to get the screw back in and the DFC linkage part of the heli would then be ok. Only question would be if the second hole would significantly weaken the shaft. I don't think so since that part of the shaft would still be inside the head.

More on this later as it is not a hard fix to try.
__________________
AMA #118235
BobHyatt is offline        Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 07-03-2020, 11:25 AM   #2 (permalink)
Registered Users
 

Join Date: Jul 2016
Default

It almost seems easier to find a longer elevator link. I was messing with mine yesterday and I shortened the aileron linkages as far as they can and got the elevator link at probably max length. I did a couple of test hovers and it seems to work but still feel uncomfortable flying it with the elevator link at its tippy toes. I wonder how the RTF version is setup.
mechrome is offline        Reply With Quote Quick reply to this message
Old 07-03-2020, 10:29 PM   #3 (permalink)
Registered Users
 
Posts: 443
 
My HF Map location
Join Date: Mar 2008
Default

Nice work Bob! Very good info here.

Jay.
jayrat is online now        Reply With Quote Quick reply to this message
Old 07-04-2020, 02:13 AM   #4 (permalink)
Registered Users
 

Join Date: Mar 2012
Default

Great info, thank you for that, it astounds me that Align have made this error!

Just a thought, can you not just buy threaded rod and make a longer elevator link, or does such stuff not exist?
Paul_F is offline        Reply With Quote Quick reply to this message
Old 07-05-2020, 02:17 PM   #5 (permalink)
Registered Users
 
Posts: 443
 
My HF Map location
Join Date: Mar 2008
Default

Yes, Iíve read that someone has done this. Not sure if youíre able to get 90 degrees at mid stick while going that route though.

Jay.
jayrat is online now        Reply With Quote Quick reply to this message
Old 07-05-2020, 03:30 PM   #6 (permalink)
Registered Users
Thread Starter Thread Starter
 

Join Date: Apr 2020
Location: Birmingham, AL
Default

I'm assuming you could use a dremel to cut 'em at any length you want. Would be a minor headache to level/zero the swash since you would have to remove one end to adjust...

BTW you can't get by with out cutting the DFC links. I tested last night and you can't get the pitch to go anywhere near zero at 50%. But it works, so I'm happy.
jayrat likes this.
__________________
AMA #118235
BobHyatt is offline        Reply With Quote Quick reply to this message
Reply




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.
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


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.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.

SEO by vBSEO 3.6.1