Wednesday, June 6, 2012

Re: [Electric Boats] Outboard.. from scratch (was: Electric speedboat revisited)

 

CV joints get pretty bulky and do most of their duty in straight neutral line. if you're into R/C model cars, very similar to dogbones and drive-cups, when they're run at steeper angles all the time they chew themselves up pretty fast (Associated RC-10 as example). raising an RC-10 on its springs for ground clearance is a popular idea but hellish on moving parts.
I'm no engineer, just know from observation (very mechanically inclined), have had experience as mechanic and machinist too. I've also played with a LOT of R/C model boats, have a couple graupner's U-joint steerable stern drives, they get really loud in tight turns, call it "toggling stress"? they're a lot like a U-joint from a wrench set, put em at much of an angle they start kinking, so I dont see em as a viable-reliable option for transfer.
chain or belt sure takes some room, and have their limits too for speed and power.
 
last note about it I'd yahell searched "right angle drive" as I was replying, some pretty big ones for about 120-180 bucks, precision high speed high power, 1:1 ratio and sealed.
the casings werent physically huge, had good size shafts. stumbled onto one and cant find it now of course.
not tryin to be negative, just relating some personal experience with mechanical stuff. theres reason theyre all using right angle bevel gears, if there were better and more reliable I'm sure theyed be doing it.
 
mentioned before, small hydroplane racing gears (1:1 is popular I'm seeing now)
is a likely better solution for outboard electric conversion.
--- On Wed, 6/6/12, Craig Carmichael <craig@saers.com> wrote:

From: Craig Carmichael <craig@saers.com>
Subject: Re: [Electric Boats] Outboard.. from scratch (was: Electric speedboat revisited)
To: electricboats@yahoogroups.com
Date: Wednesday, June 6, 2012, 1:05 PM

 

>U-joints? how long are they gonna put up with being power-stressed?

I intend to find out. I think they should be more efficient than
gears. At least they should generate little heat, and I intend that
they'll be running in oil. I'm somewhat concerned about using just
two U-joints at 45º each, tho it would fit easiest. might be enough.
I'm more confident that three, each bending 30º, would run smoothly.
Four at 22.5º I hope would be overkill.

If they wear out quickly I may end up getting more sophisticated and
making ones with bronze bushings or ball bearings for the job.

Or there's CV joints, which are always twisting under power stress,
and with only grease for lubrication. I've never actually looked at
one open.

The smaller it all can be, the thinner the bottom end can be.

Craig

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