Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: hazmat on June 05, 2010, 05:04:26 pm

Title: Flexible prop shafts
Post by: hazmat on June 05, 2010, 05:04:26 pm

Nice little problem for you experts.
I want to run a propeller from an very offset motor. (Long long story) :D :D :D :D
It's not very elegant using multiple universal couplings so is there such a thing as flexible prop shafts?
For example, an idea I was given was using a speedo cable. {:-{
Any learned ideas guys???

Paul

Title: Re: Flexible prop shafts
Post by: andyn on June 05, 2010, 05:43:57 pm

Depends what motor you're running. If it's a small one you can use an etti wire drive, or is it's quite big you'll need a full flexi setup, which arent all that cheap.

Title: Re: Flexible prop shafts
Post by: Tombsy on June 05, 2010, 06:33:31 pm

Graupner has some flexible couplers, I don't know if they would work for you.
http://www.offshoreelectrics.com/proddetail.php?prod=grp-3345 (http://www.offshoreelectrics.com/proddetail.php?prod=grp-3345)

There are complete flex shafts on the site as well.

Title: Re: Flexible prop shafts
Post by: andyn on June 05, 2010, 06:44:59 pm

Bear in mind Flexi's can only go in one direction, mostly anticlockwise, though clockwise rotation shafts are available.

Title: Re: Flexible prop shafts
Post by: Shipmate60 on June 05, 2010, 07:41:22 pm

Have you thought about a toothed belt drive.

Bob

Title: Re: Flexible prop shafts
Post by: hazmat on June 05, 2010, 09:55:07 pm

The thought about cable only capable of going one way as discussed when the idea of using a speedo cable was thought of.
Apparently they are not wound in the same way as Belden or steel wire like what you buy from B&q and they can go backwards. (verification needed if there is an automotive engineer reading this)

Lots of double couplers was thought about but the basic layout is shown in the sketch below. As the angles were over 30 degrees, and as the bulkheads are fiber glassed in and room is 'tight', well see what you think? Tip to tail 440cms.Beam 110cms and moving the rudder servo is not an option.

Oh yes. motor size 550.

Paul

(http://s4.postimage.org/6uYUi.jpg) (http://www.postimage.org/image.php?v=aV6uYUi)

Title: Re: Flexible prop shafts
Post by: Tombsy on June 05, 2010, 11:48:53 pm

Can you angle the new motor a little? Then your bends won't be so severe, I think a flex shaft would work just make gentle bends in your brass.
I have flex shafts in both electric and nitro race boats, for your RPM's I think you would be fine.
Something like this maybe
http://www.offshoreelectrics.com/proddetail.php?prod=oct-oc098L-24c (http://www.offshoreelectrics.com/proddetail.php?prod=oct-oc098L-24c)
Available assembled or unassembled.

Title: Re: Flexible prop shafts
Post by: hazmat on June 06, 2010, 12:31:40 pm

Tombsy.
That's great, thanks for your help.

Paul