HDX300 rotational, head to swash, slop eliminator

[Rebuild]

This collar and swiveling spring driver (I am calling a swash follower for the lack of a better term) turns the swash and keeps everything 90/90 degrees between head and swash by driving the swash from a fixed point on the main shaft. The pushrod frames remain centered, vertically, around the main blade grips. It got rid of all the collective surprises and cyclic ticks I had been experiencing with the HDX300 head and swash. So now , since the concept is solid, I will go ahead and build one out of a brass collar and more precisely formed driving wire. It does not interfere with collective/cyclic swash movement either. Anyone experiencing the problems I had with this head may want to give it a go. FWIW :wink:

[Finless]

GREAT work... I noticed this problem right off the bat and told Steve something was needed like this.

I am going to have to look if it interfers with my collective setup when cyclic is also applied at full pitch.

Bob

[Rebuild]

Finless Bob, my HDX head was practically non-flyable the way it was! It would be nice to get a nice shiney machined unit to take care of the problem, for sure. I get no interference but I know you like your set-ups with the most pitch the machine is capable of. I would hesitate to do this, but just had a thought that the hub could be shallow drilled 90 degrees from the set screws to support some type of a swash driving mechanism. That would take any interference issues off the table. Yikes!!! I would probably screw up the head with myself attempting this though!

[Rebuild]

Since there was some interest in this simple little swash driver thingy, I am posting these pics of the refined version. This one uses a brass collar, as opposed to the proto's aluminum one, and brass insert to size it to the 3mm main shaft. It does not restrict swash movements in any way (on my set up anyway) and really does the trick of taking the slop out. Again FWIW? :)

[Finless]

NICE WORK!

I gotta go make one :)

I will show this to Steve at HDX and see if they can incorporate this into the next version. Unless you want to show him?

Bob

[Rebuild]

No Finless, you go ahead and show it to Steve if you want. This thing works fine but maybe you guys can improve on it or come up with an easier way to do the same thing. Thanks for the replies, I was beginning to think I was the only one having any concerns with this head!

[Skiddz]

Glad I stumbled across this thread.. I was getting ready to crack open my wallet and buy one of these little guys.. I think I'll wait and see if the "fix" is incorporated into future versions.

[edzinator]

Glad I stumbled across this thread.. I was getting ready to crack open my wallet and buy one of these little guys.. I think I'll wait and see if the "fix" is incorporated into future versions.

I found this to be trouble as well, only I had some Hummingbird 3D Pro parts on the bench and a bit of tinkering... unit has very little slop now at least in my heli.

edz

I do like your fix better! as you see mine has very little of the hdx300 on the head.

[Skiddz]

Not seeing exactly what the fix was there...

[Rebuild]

The HDX head has the flybar over the main rotor. I see what you have added here but it will not help the HDX flybar over configuration. Your linkages are much shorter with the flybar below the main and vertical pushrods so what you have done here is excellent for your heads configuration but the HDX head has a long angled control rod from the swash to the upper mixer levers that flips back and forth causing the pitch slop. This angle would run into interference with a stationary guide, hence, the guide must pivot to accomodate the normal excursions of the pushrod.

[bluemooone]

There is a bind point in head . too much play in it.

[Skiddz]

I'd love to see this head play issue in person. I think Rebuild's fix is pretty slick but I'm hesitant to buy this little bugger to replace by Blade CP if I've got to fabricate parts to fix a problem.

Finless, any news back from Steve on a potential fix?

[Rebuild]

I am completely in the dark as to why some people with this head do not seem to have a problem with it. The first time I spooled it up and went into a hover the thing would jump into the rafters and slam the floor from collective excursions. I had concerns about this slop before I spun it up the first time, like Finless, but had heard only of fit to main shaft wobble problems that have since been cleared up. The only possibility I see here, is that I carefully sized the ball links so perhaps the underlying problem(of which ther definately is) was merely amplified by a freed up set of linkages throughout the head. Hell! I don't know but I will say that since I have tamed the little beast it spins up and operates as precisely as it looks. I would not discourage anyone from fitting one of these to their heli but just to be aware of the possibility of experiencing this one minor hitch. Once fixed, it is a mighty fine rotor head. I am really puzzled though as to why Heli Direct has not received any negative feedback in regards to this. Am I the only one? :dontknow

[bluemooone]

As soon as I get time I gotta make one of these . Also gota get tail to hold somehow (zoom gyro/belt) tail wants to move in either direction (mostlly to the right )

[hdx300hope]

Rebuild i am having the same problem with mine and i was wondering if you would consider making a few of those for sale? I would definatelly buy a few.

[Rebuild]

Rebuild i am having the same problem with mine and i was wondering if you would consider making a few of those for sale? I would definatelly buy a few.


The thing is really easy to make..honest! Just go ahead and use a collar that will fit main shaft and drill a couple of holes. Bend up a driver wire and you got it. This one is still working great so far but I am hesitant to make some up as yet until I fly it alot more to see how well it works over the long haul. This is just a proof of concept thing I threw together that you or anyone out there can take and refine or modify as you see fit until something better comes along. Someone with the equipment to machine a driver mechanism perhaps with bearings for the lever assembly could knock out a really precision driver along these lines but I just don't have the resources to pull something like that off. Give it a try and if you can't get one of these things put together, I will consider making you one up to try out. Just keep in touch so I'll know if you get something going or not! :wink:

[johnnychimpo]

I think an easier fix would be to just sell some plastic univeral joints that actually ride along side the blade holders. Good fix though. Its a better idea than what i came up with so far. Hope HD comes out with somthing like this.

[ImAcracker]

Im having pretty good luck with using the plastic hoops from my blade CP head. Only thing is that they are a bit shorter so you gotta mess with the pitch and bell hiller linkage to get the pitch correct. Im also not sure if they will alow for correct negative pitch. But Im not near any stage of going inverted yet so it works fine for me.

http://static.flickr.com/86/231548662_5de77c5492_o.jpg

[Rebuild]

I made the gap in the pushrod frames narrower with some split down the middle fuel tubing at first and it helped but still there was the fact that the blade grips must be in contact with the pushrod frame to push the swash around. I chose to drive the swash directly from the main shaft so there is no contact between the frames and the blade holders. I figured these parts do not move in unison during normal operation so isolating their individual movement would be, at the least, desirable. Also, the little driver assemblies I am using (on two helis now) are getting quite a work-out and so far have not failed or shown any signs of wear. :D

[johnnychimpo]

I just cant understand how the manufacture built these heads and some how didnt notice this flaw. Its sad that we have to come up with a fix for it. :arggg:

[Rebuild]

I would be really curious to know why the great majority of people flying this HD head do not seem to have a problem as is. In my case, my rotor system just "Daffy Ducked" all over the place. When I took that slop out it was like a night and day difference and it spun-up/flew perfectly. I guarantee you this was not whining, I absolute had an un-flyable system on my heli until I put the swash mod on. As long a the majority of folks with the HDX head are happy with it as is and not experiencing this same problem to some degree, that's good, I really do not expect any HD modifications forthcoming. Something strange going on here as even Finless Bob, anticipating a problem in this area, must have flown the head by now and had no problem with it as I am sure he would have posted something to the effect. :dontknow