RunRyder - MA Main Shaft Question

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Miniature Aircraft Nitro/Gas Helicopters > MA Main Shaft Question

Jesper
Senior Heliman
Location: Jönköping, Sweden

I recently had to replace the main shaft on my Stratus after an unfortunate incident. When I took it out to test fly it, I noticed that my hovering point was much higher than normal (3/4 stick instead of 1/2). In forward flight I didn't have enough collective.

After landing, I checked my collective and found that all curves had been lowered by about 3 degrees. During the rebuild I did nothing that could have caused this.

My question is:

Are there differnt length main shafts? I thought that the ones I had was MA120-10, but I am not sure since I put the bag in the garbage. The one that was in the heli when I crashed is 187mm between the holes. I havent been able to measure the new one now that it's installed in the heli, but I am thinking it's longer??

/Jesper

07-18-2008 12:30 PM

rotaryfalcon
Heliman
Location: Social Circle, Ga. USA

I recently bought a new shaft for my Pro and it was 3mm longer than the original (the product listing advised of this). This is probably the difference you may have.

07-19-2008 12:29 AM

Jesper
Senior Heliman
Location: Jönköping, Sweden

Ok, I guess I must have had a short one in there before and now I replaced it with a long one causing a reduction in pitch.

Thanks,

Jesper

07-19-2008 11:13 PM

lfalsetto
Veteran
Location: COLORADO

The 120-10 has about 3/4 of an inch after the bottom hole. The older shaft does not. The 120-10 will replace the older shaft but that should not change your curves. Did the links get switched around? By the way did you find the shaft hard to get into the bearings, my last replacement was a real pain the tolerance is so close that I had to really struggle to get the shaft in the bearings.

07-20-2008 03:33 AM

HOMEPAGE

Jesper
Senior Heliman
Location: Jönköping, Sweden

I only had to replace one of the links going to blade grip, I used this one to adjust the tracking with the new blades. All other links remain untouched.

If the old shaft does not have the app. 3/4" below the lower hole, it wouldn't fit the Stratus since the lower end of the shaft below the hole passes through a bearing.

I had no problems with the main shaft passing through the bearings. However, I have had this problem with spindle shaft bearings several times.

/Jesper

07-20-2008 11:25 AM

Jesper
Senior Heliman
Location: Jönköping, Sweden

Could someone measure the distance between the holes on their main shaft? The one I had before was appr. 187mm.

Thanks,

Jesper

07-20-2008 11:26 AM

adcnh
Senior Heliman
Location: Raymond, NH.

the overall length of a 120-10 is 8.25 in or 209.5 MM i think. Yes their was an extended main shaft bout 3Mm longer. You have the new one now. Just reset the linkage to for 0 at center. you will have more + and - now

Helli's are a Love hate relation ship, I love them my wife hates them

07-20-2008 11:49 AM

stanc
Veteran
Location: Conroe, TX

I have a new 120-10 and it measures 187mm between the holes and 15.7mm, not quite 5/8" from the bottom hole to the end.

Stan
2 x Ion X2
eStartus
eAvro90
Performance Plus Lipo Packs

07-20-2008 12:59 PM

Oneyeflyr
Heliman
Location: Enid, Oklahoma - USA

Wow, I just noticed that...

I was having the same problem too!

I just thought I messed up the linkages or something when I put mine back together.

3mm makes quite a difference, doesn't it? I'll fix it tonight.

He who lands hard, makes brown skid marks

07-31-2008 09:09 PM

vulcan1
Heliman
Location: Alberta, Canada

If you are having problems with the shaft being snug as the tolerances are so close an old trick I have used for years as a mech was to put the shaft in the freezer for a bit. That will shrink the shaft a touch until it warms up. The same as when removing bearings that are to tight I use a soldering iron to heat the bearing. It does not need to be to hot to get some play.
John

Gear down, locked and welded

08-01-2008 12:47 AM

blt4ice
Veteran
Location: Newark, DE

You really should recheck all of your pitches after a crash just to make sure a link didn't go out of whack as well.

Brian
Heli tools used: Torch, Pipe Wrench, 4 ft. crowbar

08-01-2008 05:26 PM

Oneyeflyr
Heliman
Location: Enid, Oklahoma - USA

good idea... I'll do that too. Last crash was an idle-up issue where I forgot to flip the switch before the heli.

He who lands hard, makes brown skid marks

08-01-2008 05:50 PM

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Miniature Aircraft Nitro/Gas Helicopters > MA Main Shaft Question

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