Wire Drive for a .45 Rigger Questions

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Brandon Atwell

Well-Known Member
Joined
Mar 11, 2012
Messages
1,202
Hey guys!

I’ve been picking through a few threads and reading on the wire drive systems. Has there been any heads up comparisons between a wire drive system and a shaft system on a .45? I read through Bob’s post previously on his .12 and wanted to get some opinions on the applicability of those results to a .45

Also, do these systems require certain struts or can you stick with say a Zipp or BB strut? Who is the go to for buying the kits for setting up a wire drive system?

Any other recommendations?

Thanks for any insight!
 
Hello Brandon,
I don't have any exact data from a 45 motor, but I have a lot from FE riggers with equal power. A well designed wire drive will result in several hundred more RPM with all other things being equal. A 45 motor probably needs a 2.5mm or .098" wire diameter. In this size you need a very carefully planned bend in the wire to avoid excess friction. It also goes without saying it needs to be a single bend, no S-bends.

Jeff Wholt is making wires and stub shafts for the smaller sizes. Brent Byers on JRCBD is selling 1/8" wire drives for gas boats. 1/8" is too much for a 45 boat.
Ball bearing struts are preferred depending on how much side load you have at the strut. Leaded teflon bushings will work fine in most applications.

-Tyler
 
Hello Brandon,
I don't have any exact data from a 45 motor, but I have a lot from FE riggers with equal power. A well designed wire drive will result in several hundred more RPM with all other things being equal. A 45 motor probably needs a 2.5mm or .098" wire diameter. In this size you need a very carefully planned bend in the wire to avoid excess friction. It also goes without saying it needs to be a single bend, no S-bends.

Jeff Wholt is making wires and stub shafts for the smaller sizes. Brent Byers on JRCBD is selling 1/8" wire drives for gas boats. 1/8" is too much for a 45 boat.
Ball bearing struts are preferred depending on how much side load you have at the strut. Leaded teflon bushings will work fine in most applications.

-Tyler

Hi Tyler
How does the lead Teflon compare to ball bearing in performance with the wire drive? Off hand I’m thinking there would be some loss.
Thanks John
 
Hello John,

The advantage of ball bearings starts to shine when there is a significant radial forces at the stubshaft from a tight bend in the wire. So a very gentle gradual bend over a long length will show very little benefit between BB and bushings. A tight bend or very stiff wire will show a measurable difference as the ball bearing will take the side load more efficiently. A downside though is the ball bearings will not last very long with high side load compared to bushings. The bushings last a long time. For SAW and TT boats, ball bearings are worth it. For heat racing boats leaded Teflon is fine.

-Tyler
 
Thanks, I ran lead teflon for a few years back in the solid shaft days with great success. I agree on the ball bearings, those balls are really small, short life, we used to buy them dozens at a time.
John
 
Thanks for the replies guys, so for bushing the strut are they being machined and inserted, or are there readily available bushings/ bearings for production struts that just fit inside?

I run 3/16 shafts in my .21 hydro and may be looking to convert it over as well pending the success of the .45’s if we go that route.
 
On my 45 rigger when I built it, I used .125 diameter music wire. That was all that I could find at the time that I believed would work. The .098 wire would probably also work but I have not tried it. Our boats using nitro engines need a little larger wire diameter for the same torque compared to the electric to make up for the engine pulses. The best wire has a ground finish and then I polish it to remove any surface imperfections where stress cracks begin.

On this rigger I used 2 pair if 3/16 X 3/8 ball bearings for the strut. (They have much larger balls) leaving the outer shield on the outside bearings and using automotive engine camshaft break-in lube for lubricant. This lubricant is designed for very high loads.
As Tyler said, use a very gradual bend in the wire.
I have ran this boat a lot and have not had a problem.....yet.

Charles
 
Interesting..... compared to ASTM A228 music wire, Hi Mod carbon fiber rods have an ultimate tensile strength
rating of 3447 MPa as compared to 2450 MPa for the music wire..... Modulus is 228 GPa as compared to 198 GPa
for music wire.
Have done some thought experiments on a 'wire drive' for 45 powered lightweight hydros, but didn't get any further.
 
Let us know the results when you test .....

Will do Charles! I appreciate the suggestions. I think we will build one hull with the wire drive setup and one without for a heads-up comparison, unless it is viable to easily switch between wire and 3/16 shafts on the same hull for a better comparison?

Still some time off from getting to this stage but planning ahead!
 
Interesting..... compared to ASTM A228 music wire, Hi Mod carbon fiber rods have an ultimate tensile strength
rating of 3447 MPa as compared to 2450 MPa for the music wire..... Modulus is 228 GPa as compared to 198 GPa
for music wire.
Have done some thought experiments on a 'wire drive' for 45 powered lightweight hydros, but didn't get any further.
Hey Tim,

Remember the majority of carbon's tensile strength is in the axial direction. Something like pultruded rod where all the fibers are aligned would not be a good choice for torsion like a wire drive sees. You would need to find a helical wound carbon fiber rod with interwoven fibers at 45Deg or thereabouts to be able to handle the torsional loads.

-Tyler
 
Hey Tim,

Remember the majority of carbon's tensile strength is in the axial direction. Something like pultruded rod where all the fibers are aligned would not be a good choice for torsion like a wire drive sees. You would need to find a helical wound carbon fiber rod with interwoven fibers at 45Deg or thereabouts to be able to handle the torsional loads.

-Tyler

Exactly, and that's why we halted on that concept, pretty much. Seemed pultruded

was the only option we found, in limited research.

Thanks!
 
Interesting..... compared to ASTM A228 music wire, Hi Mod carbon fiber rods have an ultimate tensile strength
rating of 3447 MPa as compared to 2450 MPa for the music wire..... Modulus is 228 GPa as compared to 198 GPa
for music wire.
Have done some thought experiments on a 'wire drive' for 45 powered lightweight hydros, but didn't get any further.

The stiffness of the carbon fiber may work against you when you need it to bend and flex some. Not sure if the ease of bend and the fatigue life of carbon is going to be superior to something made of metal. Surface hardness isn't there for sure. Wear may be biggest issue.
 
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