From: Guillemot@aol.com
Date: Wed, 22 Mar 1995 22:56:26 -0500
Message-Id: <950322224714_58164061@aol.com>
To: baidarka@imagelan.com
Subject: Re: Paddling...
>> In light of the above KE solution I can see where by using both lift
>> propulsion and drag propulsion you may end up imparting less KE to the
water
>>and end up with a more efficient paddle stroke.
>
> Note that the key to more efficient energy transfer is less paddle slip.
> If the paddle is slipping, you must be losing energy. I do think it
> possible to use lift propulsion to reduce the paddle slip.
I haven't thought this through yet but here is my initial thinking:
The basic principle I missed with my drag arguement is that, due to the V^2
term in Kinetic Energy, thrust is more efficient when moving more mass with a
lower velocity.
I suspect that adding lift to the system may improve efficiency by reducing
the backwards velocity of the paddle while still applying the same force. I
guess in a sense this is reducing slip, but... Well here's an example:
Pull a given paddle straight back at a given force (F). All your propulsion
is drag. It will slip. Now add a sideways component. This will create a
certain amount of lift force (Fl). Now not as much backwards "drag" force
(Fd) is required so the backwards velocity can be reduced without sacrificing
propulsion Fl+Fd = F. By combining two lower velocity motions do you get
something more efficient than one higher velocity?
These are preliminary ideas. Can anyone shoot holes in it before I look
further?
Nick