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MS Composit › Play between tail hub and tail blade holder screw.
11-04-2004 02:43 AM  13 years agoPost 1
yapjy

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Singapore

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When I draw an imaginary line from blade tip to blade tip, this imaginary line is not parallel to the tail boom.

Taking a closer look, I found that if I try to push the tail blade tip slightly with my finger, I can observe some lateral play between the tail hub and the tail blade holder screw.

I thought about this and guess that when the tail blades are spinning, this play should not affect flight quality because centrifugal force will pull the tail blade straight.

I confirm this by spooling up the H2 on the ground and observe the spinning blades. An imaginary line drawn tip to tip on the spinning blades showed that the spinning blades are parallel to the tail boom.

Hence, it seems that this "non-parallelness" only happens when the tail blades are static.

I like to seek opinions on if this lateral play can cause tail wag.

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11-04-2004 06:10 PM  13 years agoPost 2
Roger Hamilton

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Surrey, England

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If the tail hub scres are misaligned then this will normally cause a tail vibe. However it is possible that they are both similarly misaligned so you are maybe getting minimal vibration but poor control over pitch changes, hence the wag.

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11-04-2004 09:08 PM  13 years agoPost 3
Razmo

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Chicago

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I don't think he's experiencing any wag. He's just curious if the lateral play can contribute to wag.

I have the same lateral play and wondered myself. I'd guess it's possible if the build of the H2 isn't correct, otherwise it's shouldn't contribute.

Raz

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11-04-2004 09:52 PM  13 years agoPost 4
OT45

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Kingston, NY

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yapjy,

The play is normal in the stock tail. I had tail wag issues initially as well. To solve your wag, make sure you didn't do what I did:

I made a build error during assembly that lead to long frustrations. Due to E431(tail hub) having poorly threaded holes, I ended up threadlocking the E058 rods into the hub. This allowed the blade grips to rotate on E058 but bind under flight loads. This initially worked fine without a heading lock gyro. When I switched to my gy401 the tail wag appeared and didn't go away. It didn't matter what gain, how much grease on the threads, how high the head speed etc... I simply had to rebuild the tail (per instructions) so that the threaded rods pivot inside the metal hub and not in the plastic!

So if you were one of the unlucky recipients of a poorly machined E431, I suggest re-tapping the threads (M2) and glueing the rods into the grips for safety. Don't forget to grease the hub and E058.

My HII has been rock steady since.

scratch building is not just for planks

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11-05-2004 12:42 AM  13 years agoPost 5
yapjy

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Singapore

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Thanks.

I have the infamous tail wag

I remember screwing and unscrewing the E058 rods into the plastic tail blade holder during building.
I wanted to get the E058 straight. Could the screwing and unscrewing deform the threads in the plastic tail blade holder?
In flight, the loads may cause the E058 alignment to go out because of deform threads?

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11-05-2004 01:52 AM  13 years agoPost 6
Razmo

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Chicago

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Be sure to check the pitch slider sleeve for a true fit. If the pitch slider sleeve isn't rotating true on the output shaft, this can easily cause a wag. Not only was my brass sleeve warped that came in the kit but the second I received was warped as well.

I attached a picture to illustrate my problem. Try removing the main blades and run up the tail. If you see or even feel the pitchslider wobbling at all, more than likely you have a bad pitch slider sleeve.


Raz

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11-05-2004 02:44 AM  13 years agoPost 7
yapjy

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Singapore

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Thanks Razmo,
It didn't occur to me that the seemingly rigid pitch slider can be wrapped!

I will check on that.

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11-05-2004 04:23 AM  13 years agoPost 8
OT45

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Kingston, NY

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yapjy,

Clean the threats and grips with alcohol then re-assemble using JB weld. The JB epoxy is nice and thick which will help center the rods into the blade grips. This will remove your possible excess play but more importantly prevent the rods from backing out during flight.

Razmo,

I also had a poorly machined pitch slider sleeve. I made a new one on my lathe that was close to perfect but still had the wag. It didn't go away until re-chasing the threads inside the tail hub with a tap.

scratch building is not just for planks

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11-05-2004 01:51 PM  13 years agoPost 9
yapjy

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Singapore

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When I spooled up the heli and tried to simulate the tail counter-acting the torque from the spinning main rotor head.
I done this by applying right rudder.

I found that when the tail blades are deflected(i.e blowing wind to the right), they goes out of track!!!

This is bad. I guess this pins down to the play between the tail hub and screw from the tail blade holder.

Have to visit the LHS to buy a solution.

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11-05-2004 02:23 PM  13 years agoPost 10
Bg_

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Penn. State U.

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Ditto on the messed up pitch slider. I even bought a new SS one from deetee and it still wiggles (as per Razmo's picture). But, as far as I can tell, for me this only results in a vibration in the pushrod to the tail servo (bad thing to have, I know, but I can't solve it).

I don't have any tail wagging when flying though.

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11-05-2004 03:17 PM  13 years agoPost 11
Razmo

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Chicago

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OT45,

Wow, Thanks for the note. I'm waiting on a servo from Futaba, so I haven't had the chance to test for wag just yet. I may just retap the threads anyhow since the play has been bugging me since day one.

Just to make sure I understand you correctly, can you go through your retapping procedure step by step for me?

Raz

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11-05-2004 03:24 PM  13 years agoPost 12
Razmo

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Chicago

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Bg_
I'd have Dennis send you a new one. The second of my two bad sliders was a upgraded stainless sleeve from Dennis. You and I may have bought around the same time, mine was way off. Since his most recent stock, Dennis has sent me a fresh one free of charge which seems to rotate perfectly. I get no vibration and not even a slight wobble.

Raz

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11-05-2004 11:29 PM  13 years agoPost 13
OT45

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Kingston, NY

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Razmo,

It's simple. Use a M2 tap (same thread dia. as the rods) and re-chase the threads inside E431 hub. You might want to use a "bottom tap" which has less taper at the beginning to allow for more threads to be formed at the bottom of the hole. Next is to clean out any chips stuck inside the greased tail using some alcohol\solvents. If you have access to compressed air, blow it out carefully. Make sure that the threaded rods(E058) have "clean" threads as well. During improper assembly on my heli, the slitted (screwdriver end) part of the rods spread so now that end is glued into the grips and I use the "clean" end inside the metal hub (follow my previous reply). Now re-grease the threaded bore and screw in the blade grips containing the bonded in rods. Make sure to allow for enough travel for full blade pitch. In other words, don't screw them flush with the hub. The overall idea is to make things as smooth as possible and I don't think threaded rods are an ideal bearing surface! Since bonding the rods into the plastic grips, I don't have any play there but very little still exists (~2 deg overall deflection)between the hub and rods and is needed to keep things from binding up. I hope this helps.

scratch building is not just for planks

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11-08-2004 09:20 PM  13 years agoPost 14
Razmo

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Chicago

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I may not be seeing the point here....

During assembly, I made no errors so no damage was done. I have zero play while E058 is screwed into the blade grip alone. My play resides while E058 is screwed into E431. The hub holes of E431 already seem too large. If I retap the existing threads at the same size what would I be accomplishing here?

Raz

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11-08-2004 10:35 PM  13 years agoPost 15
OT45

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Kingston, NY

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Razmo

You are correct. As I mentioned before, this is for hubs that have tight bores\bad threads. In fact mine was so tight that I had no other choice but to open up the threads or buy another unit. Sorry for the confusion.

I'm surprised that your hub is too large, as taps wear during the manufacturing process it should result in a tighter fit. The clearance hole must have been oversized... Go figure with MS quality control...

scratch building is not just for planks

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11-09-2004 04:18 AM  13 years agoPost 16
yapjy

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Singapore

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"Go figure with MS quality control..."

Lousy. I found that the size of the E058 is not consistent!
I compared a few NIP E058 with the same E431 hub and found that some E058 is abit large causing tightness and some E058 is abit small causing play!!!

Considering the important role of the E058 in the entire tail rotor system, the poor quality is totally unacceptable!.

I have since gotten a E058 that is a good fit to my E431 and is awaiting for a flight test.

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11-09-2004 03:40 PM  13 years agoPost 17
Razmo

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Chicago

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I've spent hours figuring I had bad pitch slider sleeve, which made up 4 times of completely rebuilding the tail assembly. Not only have I spent extra dollars on parts I spent extra dollars on a press so that I can remove the output shaft easily. This is before I've even ever flown it!! I now have to spend hours finding the appropriate fit of E058 and E431.....
This is rediculous!

MS needs a quality assurance department BAD!!!!!

As I always figured, I'm betting the play between my E058 and E431 is way off...

Raz

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11-13-2004 04:16 AM  13 years agoPost 18
yapjy

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Singapore

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OT45, you are right

"Clean the threats and grips with alcohol then re-assemble using JB weld. The JB epoxy is nice and thick which will help center the rods into the blade grips. This will remove your possible excess play but more importantly prevent the rods from backing out during flight. "

I found that the screw thread in one of the tail blade holder has worn out for unknown reason. This might the cause of the tail wagging that has bugged me for 3 months!!!

Fed up with the constant care the tail needed, I bought the Duzi metal tail blade holder to replace the plastic MS ones.

Cool, flight test a few moments ago and the tail wagging is gone.

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11-13-2004 11:02 AM  13 years agoPost 19
ifly65

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The Arch

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tail
SWWEEEEETTTT!!! The tail problem solved!

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11-13-2004 02:41 PM  13 years agoPost 20
OT45

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Kingston, NY

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No more tinkering and on to flying...

scratch building is not just for planks

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