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HelicopterMain Discussion › Hollow Main Shaft
03-16-2003 01:01 PM  14 years agoPost 1
Futurac

rrKey Veteran

Belgium , Europe

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We would like to produce a new Hollow Shafts from special material, which is very strong and specially designed for high tork and pressure , what is common to RC Helis.

Basicly the shaft was tested successfully at hard 3D.
we are aware of what happened to Bergen or others Hollow shafts, thats what we will prevent with the new product.
The decision is not final, but opinions wellcome.
The sample shaft for Robbe i have is only 56 grams., just to give an idea of weight.
Also , what helis you think can use those shafts?

Thanks for cooperation.

Alex (Formerly Known as RCMarket )

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03-16-2003 01:14 PM  14 years agoPost 2
Ace Dude

rrProfessor

USA

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"we are aware of what happened to Bergen or others Hollow shafts, thats what we will prevent with the new product."

What happened to Bergen?

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03-16-2003 01:29 PM  14 years agoPost 3
Futurac

rrKey Veteran

Belgium , Europe

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SHAFTS

As i understand there were few single cases , where the shaft broke during the flight,
not sure who produced it, but it was estimation of producer since not many produce this product
..

Alex (Formerly Known as RCMarket )

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03-16-2003 02:12 PM  14 years agoPost 4
z11355

rrMaster

New England

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if your hollow one is 56g, what is a
stock one?

Yes, as I recall, in a few cases, the
Bergen one failed, near the upper
bolt hole if I remember.

The Robbe design doesn't put alot
of shaft into the headblock which makes
things quite stressful.

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03-16-2003 03:19 PM  14 years agoPost 5
coop

rrApprentice

Bainbridge, NY

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I have 2 Bergen Intrepids, never had a problem with the shafts, even had a couple survive a hard crash w/o bending...I don't think it is fair to advertise your new product and pick on someones estabilished product just for a few isolated incidents. Any part is prone to failure if pushed far enough..JMO.....Coop

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03-16-2003 06:52 PM  14 years agoPost 6
helidude

rrApprentice

Sunny California

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Alex,

Add the Freya to your list.

BTW, your C-Spec should be there this week.

Let me know.

Thanks,
helidude

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03-16-2003 06:58 PM  14 years agoPost 7
Futurac

rrKey Veteran

Belgium , Europe

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Coop

i am sorry if i am insulting any one or any product, there is no idea to go down on any product, not at all.
i picked the name because i saw it at some article a while ago, thats it,
put it this way, i am still using same bergen shafts on my own helis, so you can see that there is nothing wrong with it,
the idea to make a new product is due the intruduction of new material and new techology.

Alex (Formerly Known as RCMarket )

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03-16-2003 06:58 PM  14 years agoPost 8
corey11

rrElite Veteran

Bay Area, California

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whats the point haveing a hollow shaft?

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03-16-2003 08:25 PM  14 years agoPost 9
BQuick

rrNovice

Staatsburg, NY

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The strength of any shaft is mainly in the outer part of the shaft. A hollow shaft is lighter, but not much weaker.

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03-16-2003 09:08 PM  14 years agoPost 10
Wayne

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Davidsonville,​Maryland

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Just the hollow shaft won't quite do it guys. Bergain shafts are so good because he grinds them (or at least used to) on a centerless grinder, which he did after he hardened the shafts. This insured a perfectly true shaft. As I recall he did that process more than once. His main shafts were always dead on.

So, the hollow main shafts are a great idea. Don't forget to grind them though to make them straight!

As for the hardness, there is something called a rockwell hardness tester which measures how "hard" a material is. If Bergen really did have some break in flight, they were most likely too hard. If you make it too hard, it is actually brittle and could break I suppose. Beware of main shafts (cheap aftermarket ones...) that are not hardened and are not straight. A long time ago I bought some cheap aftermarket main shafts for a 30 machine, and they actually bent just doing normal forward flight and basic aerobatics.

Wayne

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03-16-2003 09:14 PM  14 years agoPost 11
Futurac

rrKey Veteran

Belgium , Europe

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Wayne

this is exactly the point we are concentrating on.
we are working together with German experts of steel, and they also provide formulas of Physics, in order to make sure we have the right material for right needs.

i am not sure it will be a cheap version of shaft, but at least it will be good.
we will not put any one heli on danger, before making sure it 1000% works.

Alex (Formerly Known as RCMarket )

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03-16-2003 09:33 PM  14 years agoPost 12
CopterDr

rrApprentice

West Plains, MO

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Futurac..................like full scale masts, a hollow main shaft would be great. I'd love to have one for my upcoming OH58D project. I'll be using the Benzin mechs and a 4 blade head. I'm not a metalurgest or machinist so making my own was way out of the question.

I wish you good luck on your project, and hope you will keep us all informed.

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03-16-2003 10:03 PM  14 years agoPost 13
Jagboy69

rrKey Veteran

Miami

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After reading this.. I just went to the table and picked my last sceadu main shaft... it is only hollow about 1 inch up each side.. If I remember correctly... a hollow shaft gets it's strength differently than a solid shaft.. It infact has two sides in which to do so... the inner and the outside.. dont believe me?? pick up a solid piece of 10mm aluminum stock at the hardware store and put it next to the hollow shaft of the same size... now whip them at someone passing by... the hollow shaft is stronger..
weird.. I would be interested in putting this theory to the test on a model helicopter...

Jason /// Sceadu50/9chp WWW.Jagboy69.com

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03-18-2003 01:26 AM  14 years agoPost 14
BQuick

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Staatsburg, NY

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A hollow shaft is NOT stronger. It's stronger per unit weight, but will be weaker than a solid shaft of the same material.

- Brad

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03-18-2003 01:57 AM  14 years agoPost 15
Blair

rrKey Veteran

Republic of​Canuckistan

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It was the Bergen main shafts in Robbe's that were the problem. I spoke with Chris Bergen last year and he confirmed it.

Problem seems to be the jesus bolt sits very high on the mast
causing greater leverage at the end of the mast.

Bob J had one let go too.

I've been flying one for two years with out a problem in a 61 Milli II.

I'd only be concerned with balls to the wall 3D flight, and or monster engines.

Since putting the YS91 in my Milli I've gone back to the stock Robbe main shaft.

Blair

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03-18-2003 08:35 PM  14 years agoPost 16
bobj

rrVeteran

United Kingdom

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Hi Blair
----------------
Bob J had one let go too.
---------------

Did I, don't remember this one?

Well I did have one go but that was only after the model boom struck in midair due to a component failure, nothing to do with the shaft really.

The problem is the 90 sized engines have moved things on a lot and there are so many guys doing far more agressive flying than only say a year ago that I don't think a hollow 10mm mainshaft is a good idea anymore, 12mm would be ok I would think but that would need a lot of changes to the machine to fit one.

Best regards
Bob J

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03-18-2003 09:16 PM  14 years agoPost 17
spincycl

rrVeteran

Marietta, GA

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I have been using Bergen shafts on my Xcell from day one. In fact I have only owned a total of three Xcell brand shafts in my whole heli career. The Bergen shafts have to be hit HARD to even get tweaked. In fact most of the time, a crash will only bend them so little that it's hard to even detect it without dial indicating it on V-blocks.

I did a hardness test on one and it came in at 60-62 Rockwells. The Xcell shaft came in at 35-45 max. Hardness CAN be a bad thing, so I don't fault the Xcell shafts at all, but from my experience with them, the bergens are not only harder but much stronger. They are not just hardened but tempered quite well. In fact, them being hollow has little to do with reducing weight, but it just makes it possible to thru harden/temper.

If anyone makes heli shafts of similar quality, I would not hesitate to buy them consistently. But, please make sure that the holes in the ends are the proper sizes. The bergen shafts are drilled for 3mm THREADED bolts. But, the Xcells use 3mm diameter dowel pins which are slightly larger than the holes. So, it's HARD to drill into a 62 rockwell shaft, even if its to open the hole up a couple thousandths.

You got my vote!

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03-18-2003 09:55 PM  14 years agoPost 18
Blair

rrKey Veteran

Republic of​Canuckistan

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I apologize Bob!

Your name was dropped by someone about a year ago when this same topic came up (It's been raised a few times on various forums).

Blair

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03-18-2003 11:28 PM  14 years agoPost 19
RappyTappy

rrProfessor

North Denver,​Colorado

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It was the Bergen main shafts in Robbe's that were the problem. I spoke with Chris Bergen last year and he confirmed it.

Problem seems to be the jesus bolt sits very high on the mast
causing greater leverage at the end of the mast.
Thanks for clearing up this gross MIS-INFORMATION on this thread. Just T's me off. Especially when they say
i picked the name because i saw it at some article a while ago, thats it
grrrrrrr....

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03-19-2003 01:37 AM  14 years agoPost 20
vortechZ230

rrElite Veteran

U.S.A.

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I would prefer a bigger shaft!, But, thats just my opinion.....

Blue skies, Light Winds!

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