HK450GT, 4 blade rotor, phasing issue - RC Groups
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Jan 28, 2013, 03:50 PM
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cynr100's Avatar

HK450GT, 4 blade rotor, phasing issue

I am rebuilding my HK450 to run with Flymentor and a 4 blade head to go in a MD500. As a test bed I am using a Titan 450 to test the setup.
I have yet to spin this unit up as I wanted to concentrate on blade balance and weight, I have all blades within 0.02mg and all balance to the same point. My next issue was phasing, simple process once explained, but my HK 4 blade rotor will not phase to the recommended 90degree, because of the location and size of the swash retainer I can only get 85 degree.
Does anyone see an issue with this or do I have a faulty 4 blade head.
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Jan 28, 2013, 04:49 PM
banging head on wall
skyeblu's Avatar
I don't have my 4 blade with me to check but I don't think my phase lock is 90* from my blade grips off the top of my head. I think if I have one blade over tail boom I bring bring the lock around main shaft till I get the swash ball link from the blade to the left of the one I have over the boom to line up with the anti rotation pin and I can use input for that blade and get no movement / interaction with the two blades 90* (out to sides) to the blade over the boom. You can do a search for multi blade phasing or go down to the scale heli threads . Here you go
Jan 28, 2013, 06:51 PM
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Thanks Skyblu, I have watched that informative vid explains the whole mystical "phase" thing very simply. As long as each connector rod is the same length then only 1 blade needs "phasing" and the rest should follow, but I checked anyway just to be sure.
The issue is when I line the ball link up with the antirotation pin the swash lock gets in the way before the 90deg is achieved, this follows for all blades. I said before that I could only get 85deg, I meant 95deg
Just wondered if anyone had experienced this with the HK 4 blade head, I'll experiment and post the results
Jan 29, 2013, 11:15 AM
banging head on wall
skyeblu's Avatar
That is one of the heads I have had no problems phasing it. Are your blade grip links leading or following the grip balls should be leading the grip. I remember I fought phasing on a head till I realized I had the blade grips following instead of leading. Also the lock can be moved up or down if that can give you more clearance mine is centered in the travel range of the swash. I set my swash before I phase at mid stick. Level the swash and set pitch close to 0*. I use a hex driver that drops into a blade grip bolt hole that fits with little slop and I look from the side and adjust links till I have the hex driver lined striaght up and down up with the main shaft this gets all the blades close to 0* at mid stick and then go back and readjust pitch as needed after phasing. I not home with my birds but if you haven't got it set up yet I can post a close up picture so you can see the phasing position of my setup in a couple of days when I get home if that would help.
Last edited by skyeblu; Jan 29, 2013 at 11:32 AM. Reason: to add line about pictures
Jan 29, 2013, 04:47 PM
banging head on wall
skyeblu's Avatar
here are some pics I found from an old post of mine the first shows the angle of my links on one of my 5 blade heads in phase
the second and third are one of my copterX 4 blade you can't tell much with these. I posted because the op had the swash lock assembled wrong.
When The head is in phase the ball on the swash for the swash lock and feathering shaft for the blade that in phase line up with antirotation pin. I think you can see that in picture one just above my thumb of the 5 blade. I think that is the same for the 4 blade it's been awhile since I have had to any phasing so I would have to double check when my birds are in front of me.
Last edited by skyeblu; Jan 29, 2013 at 04:56 PM.
Jan 29, 2013, 10:23 PM
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Thanks again Skyeblu, the 2nd pic held the secret. It looks like my swash lock is on backwards thereby limiting the move to 90deg. I'll check that when I get home tonight, yours is a better model than mine (HK) but the "skinny bits" on my swash lock are trailing where yours are leading. I really hope HK didn't put it together backwards
Blade grip link balls are leading edge.

Thanks again, I'm feeling more confident about this build
Jan 29, 2013, 11:09 PM
banging head on wall
skyeblu's Avatar
I have the HK 4 blade also! these pictures up right now I posted about a year ago and pulled them out of my attachments here. When I get back to my place about 500 miles away right now but that will be a couple of days. I can take a picture of the HK head and post it. I think I have that on my A109 right now. I'm experimenting with a short dfc main shaft to bring the rotors down closer to the doghouse we'll see
Feb 02, 2013, 01:05 AM
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Your CopterX is obviously a better build. Your swash lock allows rod clearance and achieves a 90deg phase.
Here is the HK 4 blade, notice how the rod is hard up against the swash lock and the trailing blade ball link is just short of alignment with the anti rotation bar

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Guess I'll just wait until I spin it up and see if there are any control issues.

When in doubt procrastinate
Feb 02, 2013, 03:24 AM
banging head on wall
skyeblu's Avatar
Looks like you have the lock assembled wrong here is a short video of my head phased. If you watch with aileron stick the red ziptie moves and there is no movement at all with the yellow ziptie. I rewatched the video and I have a slight interaction still with the yellow zip tie moving it needs just a slight tweek still for no movement. I think you can see in the picture the ball alignment is off a bit oops! as I describe below. The front and rear blades will move but the blade out to the sides should remain still no movment. With the video I tried to get the lock assembly so you can see it assembled. I have to upload the videos to youtube will be up in a little while. The first video needs to be opened to view it shows the blade grip interaction when in phase
phasing 001 (0 min 53 sec)

here I tried to shown the clearance you should have between the link and the lock pivot
phasing 003 (0 min 17 sec)

In the picture If you look into the antirotation bracket from the back you can see the grip link from the right blade grip is seen and the blade grip to the back of the heli is centered above the boom. So you pretty much have the anti rotation pin the swash ball from your right blade and the rear blade all in alignment. Hope this might be of help
Last edited by skyeblu; Feb 02, 2013 at 06:39 AM. Reason: add video and picture and correct spelling
Feb 03, 2013, 12:54 AM
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Originally Posted by skyeblu
Looks like you have the lock assembled wrong................... Hope this might be of help
Bang on target Skyeblu, your help greatly appreciated. Your vids were are the only ones I have seen that show the swash lock in detail.
I installed mine "as received", the dogleg to swash was reversed, the cupclamp could have been me when placing on the shaft.
A before and after for anyone esle following the thread.

Thanks again Skyeblu, your a champion

Name: before.JPG
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Name: after.JPG
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Size: 55.3 KB
Feb 03, 2013, 01:05 AM
banging head on wall
skyeblu's Avatar
Good to see that you have it sorted out. In my video I think my phasing is just a very small bit to advanced. I have a little bit of interaction still. When you do the phasing have one blade over the boom just to make sure you realize that and a good starting point is getting the swash balls and blade grips close and the fine tune. I can take that head off and change a main shaft reassemble and phase it in no time now. If I use that as a start point. Also to add I did the same thing when I first hk 4 blade but I had to figure it out my self and almost gave up more than once. Would be nice to see it after you are done with your build . I have a flymentor that I was going to use with the multi blade heads but was given the impression that they wouldn't work right together without the flybar it is not fast enough and never finished my multi blade builds until the stabilization systems became more affordable. I have the flymentor in a V2 with 2 blades and it's fantastic the way it holds position hands off but I don't fly it much any more no real reason!. I use a tarot zyx-s and the zyx now for everything else I have.The five blade in my earleir post is for a md 500 also
Last edited by skyeblu; Feb 03, 2013 at 01:47 AM.
Feb 03, 2013, 04:10 AM
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Ahhhh......maaaaate long way to go on this build.
I spun it up after sorting the swash lock and was very happy with the overall balance and vibration level, now I need to sort throttle and pitch settings so that I achieve hover just before mid stick.
Problems arising
Present 2 blade tail is lacking in authority - new blades or 4 blade hmmm
Blade holders came loose, strip and check
FlyMentor is over reacting, disengage and set the heli trim up first then revisit the FlyMentor settings on the program box, improve the Gyro anti vibration pad.

But ....................all in good time
Feb 06, 2013, 03:46 PM
Registered User
I thought you could run straight up and down if you reversed ele and aer servos, thereby giving the require 90* phase.
is this not true?
Feb 07, 2013, 06:38 AM
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As I understand it "phasing" insures that the blade is in the required control position before it reaches the required direction of travel.
The rotor blades in motion are affected by gyroscopic precession, a phenomenon caused by the torque effect of a rotating disk.
Using a clock face, if the direction of travel required is 3 o'clock the blade pitch change would need to be in effect at 12 o'clock and revert at 6 o'clock. The torque induced by the rotor (in essence a gyroscope) causes the effect of the blade pitch to manifest itself 90deg after application.

Sounds confusing....right, took me a while to get my head around it.
Having the control rods "up & down" would probably work on a 4 point swash with some good Tx mixing.

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