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Oct 28, 2013, 05:26 AM
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Discussion

scale sub prop vs boat prop


Im designing my first submarine to be made from pvc. Im putting in 2200kv brushless motor 36mm wide x 60mm long. Im building it to achieve the highest speed possible. My question is would scale sub prop be all around better than that of a 2 or 3 bladed boat prop?
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Oct 29, 2013, 04:31 AM
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DDG 51's Avatar
If do you using high power brushless motor, with relativly high RPM per Volt, you have use 5-7 bladed Raboesh prop. I have 40-30 motor in my sub, with 7 blades 70mm prop, and result is excellent.Speed is great. But hight speed sub as a first sub ever..... I do not know, if this is good idea
Oct 29, 2013, 05:22 AM
Registered User
I get that it could run a 70mm prop but you would need a gear reduction. Im going direct drive. The recommended size for this motor is 40mm x 2.198 pitch
and im assuming thats for a 2 bladed boat prop. A 5-7 would look awesome but I not really looking for scale appearance. Im just not sure what would achieve the greatest speed without burning up my motor.
Oct 29, 2013, 12:43 PM
KC8WPF
CG Bob's Avatar
Quote:
Originally Posted by X1AaronW View Post
The recommended size for this motor is 40mm x 2.198 pitch and im assuming thats for a 2 bladed boat prop.
That's the recommended prop for a planing type boat hull. That's not necessarily the best prop for a submerged displacement hull.

Give the 40mm x 2.198 itch prop a try - don't be surprised if it doesn't work right the first few times. There may be prop torque induced problems.
Oct 29, 2013, 03:10 PM
Registered User
I figured a smaller prop would work better to help compensate for the torque. Would that help?
Nov 04, 2013, 03:37 AM
NeverAgainVolunteerYourse lf
nick_75au's Avatar
the reccomended prop is most likely for a surface drive where the prop is half out the water, Im guessing that a reduction of prop size by 25% would be needed to ensure thew motor is not overloaded in the subsurface configuration.

Nick
Nov 04, 2013, 08:43 PM
Registered User
Thats kinda what I was thinking but needed to hear it


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