High RPM on a 3/16 "flexshaft

[grsboats]

I'm curious to see how much RPM's a 3/16 flexcable can support.I'm running saw riggers and never had a failure with my shafts( low 40K) but I'm about to test a new combo that is supposed to reach 60K ......I know there are some guys running 50K with no problems.you're welcome to share your experiences. Thanks Gill

[RandyatBBY]

It is more the voltage, power and size of the prop that limits the 3/16 flex shaft. 4S with with most all motors is OK. when you go to 6S it gets touchy.

[Fluid]

I've run my SAW boats to 42,000 rpm with that size cable without problems - but I use only Hughey cables. I too wonder at what rpm the centrifugal force will contribute to cable failure - but it seems to be balanced by the tortional forces imposed by the prop. I have heard reports of others runing in excess of 50,000 rpm, but I have never witnessed this.



.

[Mike Caruso]

I've run my SAW boats to 42,000 rpm with that size cable without problems - but I use only Hughey cables. I too wonder at what rpm the centrifugal force will contribute to cable failure - but it seems to be balanced by the tortional forces imposed by the prop. I have heard reports of others runing in excess of 50,000 rpm, but I have never witnessed this.



.

Your boats stuffing box tube does it have a slight S bend, one bend or straight?
Mike

[grsboats]

Mike only one soft bend.Also I only use Hughey shafts and I saw some people in Germany running boats in the mid 50k's with no issues so as I'm about to test a new rigger with a 1527 on 8S I thought it would nice hear some comments. Thanks Gill

[Chris Harris]

I run 3/16 cable in my 8S SAW rigger at higher than 50,000 rpm
and I have not broken one yet. I did tweak one from a blow off
when the prop bit when the boat landed. It is unusable now because of the bend
in it but it still did not break. I have been running props up to 44mm
with this setup and they are Hughey cables which in my opinion are about as good
as cables get. Having a really good motor to cable coupler is really important.
This is really the weakest point and with that much rpm and power that connection sees
an incredible amount of stress. I solder the ends of my cables and this helps a lot with durability.

Hope this helps,
Chris

[RandyatBBY]

Hi Chris

You been to any Olive Gardens Lately?:wink:

[RaceMechaniX]

Likewise I have run a 1527 on 6S and once with 8S and no problems. A very true coupler is key as is a true joint at the stub shaft. The prop has to be dead nuts balanced. All of mine run a single gentle bend with Teflon liners.

Tyler

[jcald2000]

No problems with 3/16 on 8s and Mod 452 on 1527/1y.
45% silver solder on cable end with 3 piece coupler and cable is polished.

[grsboats]

Thanks guys I think that I'm in the right direction as my parts are top quality ones and I spend lot of time on my props so let see what will happen with this new challenge.Chris what do you think using a 1527 1D on 6S or better stick to a 1,5D on 8S?Jim interesting input polishing the cable !Well I have the choice of both motors so it would be nice know what the experts recommend! Thanks Gill

[Chris Harris]

1527/1D can be good on 6S but don't over prop it. This setup
can be really hard on ESC's. Depending on how much pitch your running
I wouldn't run anything bigger than 45mm.

Chris

[grsboats]

I see Chris ......I'm using a SF 300 that is supposed to handle this set up well.About props I have some in this diam 44/45mm with 3,5 to 3,7 cup. My previous test with 2047 and different cups were also good but it was with the lower kv motor.Anyway I really appreciate your help and will you all know how the boat performed soon Thanks Gill

[Doug Smock]

Ditto on the 45% silver on the end of the cable. Polishing isn't a bad idea either.:wink:

[grsboats]

Yes Doug I've been doing this for the last twenty years.Thanks Gill

[urbs00007]

chris, when you run 1527 in saw can you use motor with 5mm shaft? trying to trade my 2230 for a 1527 to run straightaway. dont want failures right off the bat !!

[Chris Harris]

chris, when you run 1527 in saw can you use motor with 5mm shaft? trying to trade my 2230 for a 1527 to run straightaway. dont want failures right off the bat !!

I would not run a 5mm shaft for the 1527 in any case especially for
SAW. It just seems to be too long of a rotor for a 5mm shaft
I have seen them break and it is really ugly, usually taking out the ESC
in the process.

Chris

[gsbuickman]

prefer 3/16 flex & I generally run pro-boat shafts. I try and stay around 37k for sport boating. Like Fluid I have run 42k w/o issue. I did see a 3/16 AQ shaft fracture just behind the collet, after the prop smacked something submerged at the pond.

I am wondering about the 3/16 flex on my vintage 31" shovelnose hydro. Currently it's got a k&b .30 pushing an Octura 1460 prop.
http://www.offshoreelectrics.com/search.php

I thought it would be cool to keep it vintage with a cordite 700 class motor. I have an Astroflight 60v/50A ESC to push it with.
I am thinking of 6s power for 54,000kv. If not I could go 4s for 36000 to be safe. The thing I am wondering is how many amps that prop will pull at 1.4 x 2.36" = 3.304" ?....

Well according to the speed calculator, on 4s this prop is suppose to turn 112 mph. I'll stick to the 56.4 mph estimate on 2s.