Wednesday, March 28, 2012

Re: [Electric Boats] Re: Regen (again)

 

Tim,
 
The autoprop website said that autoprops  feathers to provide 85% "less" drag. If there is less drag from the prop it only stand to reason that there should  be less torque being imparted on the driveshaft so you're going to get less spinning and less electricity. Maybe the thing might somehow operate counter intutively and actually spin better with less drag on the boat but my gut feeling is that feathering is not going to help spin the driveshaft better. 
 
I guess someone will just have to stick one in a creek and see how it spins to be sure
 
Carter

From: Tim <haywardt@gmail.com>
To: electricboats@yahoogroups.com
Sent: Wednesday, March 28, 2012 2:01 PM
Subject: [Electric Boats] Re: Regen (again)

Eric,

I do know that you have said that no one is making more than a 100watts with regen, and I believe you. I also know that people are making a lot more than 100watts with screw impellers in streams. What I don't know is why it matters whether the water flows or the water stands still and the impeller moves. I suspect blade stall has something to do with it. An autoprop would reduce or eliminate blade stall.

I don't think an autoprop will increase performance at the optimal cruise speed. After all, it will be at one pitch at that point and shouldn't perform any better than a properly pitched fixed prop. I do think it should widen the envelope of performance so that you get better performance over a wider range of speeds. I think it will couple the drive line to the water more efficiently in varying situations.

Mostly I think it might provide interesting data.







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