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HelicopterThunder TigerOther › 50 autorotation mod from mht magazine
12-01-2005 05:50 AM  12 years agoPost 1
helidad2

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potosi mo. usa

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Has anyone done this and how hard was it to do . I just took a 50 v2 apart and it definately needs something like that. The bottom gear has been wearing on the auto hub and looks like exactly what the mod fixes . I just got this machine used and I was completely dissassembling it and I discovered the gear has worn quite a bit I ordered a new auto hub and gear but I was wondering if the mod is very hard to get done . If you have done it give us some details total cost , how much for machining cost, parts, ect. And does it make a signifigant difference?
Thanks for any info.
David

even a blind hog finds an acorn now and then

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12-01-2005 11:21 AM  12 years agoPost 2
HeliPhil

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Brentwood, Essex, UK

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I would like to know what the mod involves as well as I have not seen MHT......

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12-01-2005 02:35 PM  12 years agoPost 3
BarracudaHockey

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Jacksonville FL

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The mod involves a bearing from an electric outrunner motor and it takes the sideways stress from the tail belt off the gear.

Andy
AMA 77227
http://www.jaxrc.com

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12-01-2005 05:36 PM  12 years agoPost 4
helidad2

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basically you mill a groove into the top of the white gear and fit a bearing then you turn the auto hub to fit into the new bearing . now the top of the white gear is supported by a bearing and you can tighten the tr belt without distorting the white gear . after pulling the white gear off this used raptor and seeing the wear on the gear and hub it looks to me like it is really a nessacary mod. if i can find the bearings i am going to have the machine work done and try it. i need 2 sets

even a blind hog finds an acorn now and then

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12-01-2005 05:39 PM  12 years agoPost 5
Al Magaloff

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12,199 Posts- Enough Time Wasted. See Ya!

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Anyone have a good source for the bearing?

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12-01-2005 06:03 PM  12 years agoPost 6
pcliftonjr

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Phoenix, AZ

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I haven't had any problems with the stock unit. What's the reason for this mod?

Paul

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12-01-2005 06:31 PM  12 years agoPost 7
RobRoy

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Huntsville, Alabama

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The only problem I've had with my raptors main gears is the auto-rotation hub locking up after hard 3D maneuvers. Hopefully when I get the new Quick UK auto hub this problem will go away.

Ignorance is curable, stupidity is for life.

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12-01-2005 06:40 PM  12 years agoPost 8
andyp

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New Zealand

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Sounds like a great wee mod. Does anyone know the bearing size?

Thanks, Andrew

PS I think RobRoy is talking about the R90 hub, where this is a mod for the R50.

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12-01-2005 06:41 PM  12 years agoPost 9
rob10000

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Western Massachusettes

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The only problem I've had with my raptors main gears is the auto-rotation hub locking up after hard 3D maneuvers. Hopefully when I get the new Quick UK auto hub this problem will go away.
This discussion only applies to 30/50 Raptors.

The bearing supported white gear sounds like a great way to improve this area.

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12-01-2005 06:52 PM  12 years agoPost 10
Alexander01

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Sweden

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I don't get it...

Why would you put any bearing in there? There is no movement between the one-way clucth shaft and the white gear--

And the clutch shaft is already supported by the bearing, aka one-way bearing.

Aren't you putting stress on the main gear instead by doing that? I'd prefer to stress a less vital and more tolerant part, where some flexibility is allowed, opposite to stressing the main gear.

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12-01-2005 06:59 PM  12 years agoPost 11
BarracudaHockey

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Jacksonville FL

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Al have you read the article? If not I'll dig it out when I get home and post the part numbers he used.

Andy
AMA 77227
http://www.jaxrc.com

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12-01-2005 08:54 PM  12 years agoPost 12
helidad2

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potosi mo. usa

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Alexander01
If you look at the white gear on a 30 or 50 size raptor the white gear goes over the auto hub and has the bottom jesus bolt holding it all together . If you tension the belt it will pull the top of the white gear towards the tail boom now the auto hub and the white gear can make contact at the upper inside part of the white gear and if you take the gear off a well flown bird you will see alot of dark residue inside the part of the gear where it goes over the auto hub , and if you look at the hub we can easily see where it is making contact . the new bearing will go in the top of the white gear and fit the auto hub eliminating alot of the friction in this area ,but there is some machining that has to be done as it is detailed in a recent issue of mht . I believe after some research this is a very bad flaw in the design and tt should fix this themselves and make it available to existing owners as a mod . another thing this doesnt apply to a raptor 30 or 50 with a non driven tail ( red gear ) it is only a problem if you use the driven tail mod ( white gear ) on either heli.

even a blind hog finds an acorn now and then

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12-01-2005 09:10 PM  12 years agoPost 13
TMoore

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Cookeville, TN

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I use an aluminum hub that I made a few years ago that is stiff enough that you don't need to use a ball bearing to provide additional support.

The tail on my R50V1 is driven, no bearing needed.

TM

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12-01-2005 09:14 PM  12 years agoPost 14
w.pasman

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Netherlands

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Why would you put any bearing in there? There is no movement between the one-way clucth shaft and the white gear
I'm guessing but I think they want the bearing as high as possible, around the wide part of the autorot bearing. It must be a very large bearing, yet pretty thin in order to leave some material on the white plastic gear??
Alternatively, but offering less support to the white gear, they might fit a bearing at the part where the autorot bearing gets wide (as low as possible along the main shaft). This would offer less support to the white gear but that would make it possible to lathe away part of the autorot bearing such that the bearing does stick out only very little out of the autorot bearing.

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12-01-2005 10:31 PM  12 years agoPost 15
helibird

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St. George, UT

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Just my $0.02,

Don't bother! When I first started flying I spent hours and hours fine tuning my raptor before I realized it's a low cost plastic heli and that any benefits from all this tweaking are minimal at best. Put it together stock and fly the crap out of it.

The belt doesn't need to be tight, I keep mine so I can push it in easily 1/4 - 3/8" and don't have problems of skipping teeth. I agree that after time the white gear might develop some wear, but so what it's a ten dollar part.

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12-01-2005 10:47 PM  12 years agoPost 16
helidad2

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potosi mo. usa

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The belt doesn't need to be tight, I keep mine so I can push it in easily 1/4 - 3/8" and don't have problems of skipping teeth. I agree that after time the white gear might develop some wear, but so what it's a ten dollar part.
But if it is wearing out there has to be friction and if theres friction enough to wear those parts out it has to be dragging down the headspeed in an auto for one thing and maybe anytime the rotor is turning, so anyway you look at it that it aint good. If it can be fixed cheap and easy I will do it .

even a blind hog finds an acorn now and then

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12-01-2005 11:24 PM  12 years agoPost 17
Al Magaloff

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12,199 Posts- Enough Time Wasted. See Ya!

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Al have you read the article?
Yeah, I did. I'll look that up also.

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12-01-2005 11:35 PM  12 years agoPost 18
AirWolfRC

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42½ N, 83½ W

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I looked at this problem right when the auto gear came out.

This is only a problem during autos.

I was not able to find a proper bearing that had a low enough rolling resistance to be suitable. The ID of the bearing needs to be less than 26mm (the OD of the aluminum hub for the Raptor 30/50). I found a 25 x 32 x 4 from Boca but the seals gave too much resistance at full head speed. Actually warmed up the bearing on bench test.

In the end, I just turned the hub down to 25mm for the bottom 9mm worth to clear the inside of the auto gear but still leave a bearing surface of 26mm dia. for the top of the auto gear.

Can anyone tell me what size bearing MHW came up with ?

Wolfgang

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12-01-2005 11:51 PM  12 years agoPost 19
helibird

rrKey Veteran

St. George, UT

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But if it is wearing out there has to be friction and if theres friction enough to wear those parts out it has to be dragging down the headspeed in an auto for one thing and maybe anytime the rotor is turning, so anyway you look at it that it aint good
I still think it isn't worth all the effort, my rappy auto's great. I just looked at my white gear (heli is down for repairs ) and it has some minor discoloration at the top, it isn't worn at all. I've never replaced this gear and I've had this heli for two years so it probably has over 250 flights on it. I have seen people wear them down but it is because they have the belt way too tight and it deforming the gear and causing contact with the oneway bearing.

These are just my opinions, I have great respect for all those that have enough mechanical ability to improve their heli's flying abilities.

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12-01-2005 11:54 PM  12 years agoPost 20
AirWolfRC

rrProfessor

42½ N, 83½ W

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There are two potential problems here.

High belt tension (obvious, that's what the bearing is for) and the lower jesus bolt being too tight causing deformation of the lower auto gear making it rub on the aluminum hub (turning down the hub fixes this).

Wolfgang

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HelicopterThunder TigerOther › 50 autorotation mod from mht magazine
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