Drive Shaft question

[jodyae52]

How much effect on out put power is robbed from a drive shaft when its axial point at the motor is displaced at the axial plane of the prop shaft by say 3/4 of inch over a distance of 4-5 inches?

[Guest]

Do what?! http://www.subcommittee.com/forum/icon_surprised.gif

It is April

Do what?!

It is April 1st I suppose.

[JWLaRue]

Not enough to worry about

Not enough to worry about for our R/C models.....

-Jeff

[cstranc]

I agree with Jeff, I

I agree with Jeff, I would not worry about the loss of power.

A part of me would worry about the possibility of vibration if you have a 4-5" dogbone joining the two shafts. I am sure I have seen this length or more in models before, I would just ensure you are not putting a really powerfull motor that could ramp up the RPM, cause excessive vibrations and failure.

Of course I worry to much and break too many things

The two shaft ends are well supported right?

[jodyae52]

Drive Shaft question

Thanks for the replies, The reason I posed the question is because I was told that that deflection in my drive shaft might be the cause for the seemingly slow speed of my OTW Seehund. The fountain pumps at Carmel Indiana nearly overpowered my boat, but at my home pond the boat ran fine. Right now I am installing NiMH batteries in lieu of the heavy sealed Lead acid batteries I was using. Hopefully the difference in wieght and voltage will make the difference. What do you think?

[JWLaRue]

Hi Jody,

If I remember correctly,

Hi Jody,

If I remember correctly, you are using the OTW dive module for your Seehund and the relatively small prop that comes with the kit, yes?

I'm using the same motor and prop in my OTW Seehund and I believe that the sub would benefit from a larger prop. Bob was going to check into finding one.

What voltage are you running your motor off of? 12v?

-Jeff

[jodyae52]

Drive Shaft question

Hello Jeff,

You are correct, I am using the OTW dive module. I went to a larger prop,(I robbed one of them from my in-build OTW TypeVII) I told Bob about this, and the results were better. He said he would look into this as well, he metioned that he was being a little conservative on the prop diameter, and was worried about the prop hitting the Kort. The larger TypeVII prop fits the Kort nozzle perfectly, no interfearance problems. At present I am using 12 volts, but I have since built up a battery "stick" with NiMH's for 14 volts which are lighter than my two seal lead acid batteries. I will Let you know about how it works.

[tmsmalley]

...and stay away from "The

...and stay away from "The Pacific Vortex" (aka the Carmel fountain )

The park is unable to turn off the fountain since it acts as an aerator for the pond to keep the water in balance.

[Guest]

I expect prop shop will

I expect prop shop will have a bigger prop suitable- the original boats seemed to have a fairly bog standard three blader, but in the photos I've seen, it filled out the nozzle nicely.

I have an original Dave Diplock/Craycraft Seehund, and that came with a tiny prop as the dive module was configured direct drive.

I fitted a much larger prop which fills out the nozzle nicely, but it did require the fitment of a reduction belt drive (3:1). I initially tried this with a Speed 480, but the this motor had too high RPM, and was under a lot of strain as a result.

I've since replaced the 480 with a Buhler motor, which is a surplus item I picked up at a ham radio show. A Speed 500E might be suitable for your boat if geared down, if you want to use direct drive you may want to look at a larger 'Speed' motor- perhaps a 700 or larger.

Andy

[jodyae52]

Drive Shaft Question

I have lowered my WTC deeper into the hull which resulted in aligning the shaft with the drive motor. Now no more transition. Also I used the larger prop from my yet built-up Type VII boat, and it fits the Kort nicely no interference. Finally I installed new lighter batteries NiMH's. Results, I think I can take on the current at Carmel! a great improvement in speed, however endurance is not as great as before, sufficient though.............thanks for all your input

Regards, Jody

[JWLaRue]

Jody,

You are still using a

Jody,

You are still using a universal joint, yes?

I'll have to try using a prop from the (OTW?) Type VII kit.....sounds like just the thing!

-Jeff

[jodyae52]

Drive Shaft Question

Hello Jeff, Yes I still retained the universal. One thing I discovered that before you secure the WTC down in the cradles by turning the transmitter on with the sub powered using the throttles you know you are perfectly aligned by the sound the universal makes. Rotating the WTC from side to side while listening for that "quiet" zone of the drive shaft assures perfect alignment. I secure my WTC with plastic cable ties, or "Ty-raps" as we call them in the aviation industry.

How's that Type II coming along? are we going to see a kit offered soon?

Regards, Jody