Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Submarines => Topic started by: essex2visuvesi on February 07, 2013, 12:57:33 pm
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As some of you are well aware I am in the process of building a Robbe Seawolf. I made the fatal mistake of looking on propshops website and came across the 7 blade scimitar props which in my opinion look the business and much nicer than the 3 bladed plastic prop as supplied in the kit.
So I have decided I would like to fit one to my seawolf. My question is this... do I order one the same diameter as the robbe 3 blade or is there some formula to work out the difference?
I'm guessing a 7 blade will draw more current than a 3 but in turn will give more torque.... is this right? or are the pitches different enough as to give the same power output/current draw
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this is the prop in question
http://www.prop-shop.co.uk/index.php?section=store&sub_section=product_detail&id=781&product_type=35
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The main three factors which affect how a prop will perform are-
Diameter
Pitch
Blade area.
Secondary factors are blade shape and number of blades. Preferably the fewer blades you can get away with, the better.
That prop gives diameter but not pitch or a pitch ratio (wish Simon would standardize his system, it's very confusing), so it's difficult to give you a ballpark figure for performance, and it would only be a rough estimate at that.
What i can say is that your drive system should be able to deal with it without any difficulty, and you could even consider going to a 2" diameter prop.
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Thanks :)
I think I'll start off with the supplied prop for initial testing and then fit the 7 blade
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The main three factors which affect how a prop will perform are-
Diameter
Pitch
Blade area.
Secondary factors are blade shape and number of blades. Preferably the fewer blades you can get away with, the better.
That prop gives diameter but not pitch or a pitch ratio (wish Simon would standardize his system, it's very confusing), so it's difficult to give you a ballpark figure for performance, and it would only be a rough estimate at that.
What i can say is that your drive system should be able to deal with it without any difficulty, and you could even consider going to a 2" diameter prop.
Had a reply from Simon at prop shop and he suggested the MS/22/7/RH/BR. From what I have read on here and other forums he has a rough idea what he's doing so I'll take his advice
[/size]At 42 quid plus postage I hope he's right! {-)
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I have a six blade on mine works well and looks good. dia 2"approx.
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HHB
what motor are you using with that and at what voltage?
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kit motor and 7.2 volt nicad 3000 mah.