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Recent content by Alsee

  1. Alsee

    Blackbird Land Yacht "DDWFTTW"

    rb1957: this design requires the propeller to be fixed dead ahead the propeller is providing thrust for the cart (to go forward) Right and right. rb1957: i don't see these propeller blades as being on a "beam reach" Right. It's a broad reach. (For the non-sailors, "broad reach" means the sail...
  2. Alsee

    Blackbird Land Yacht "DDWFTTW"

    rb1957: i don't see this cart tacking downwind That's the neat part of this design. There's no need for the *entire cart* to tack. The only thing that truly need to be tacking across the wind is the *sail*. On a conventional sailcraft the sail is mounted directly to the body of the craft, and...
  3. Alsee

    Blackbird Land Yacht "DDWFTTW"

    Correction. I meant to say: "From the point of view of the ground, wind energy is going into the cart, part of that energy drives the prop to spin, the rest accelerates the CART". I accidentally wrote the last word as "prop" instead of "cart". rb1957: if there's no wind then there's no motive...
  4. Alsee

    Blackbird Land Yacht "DDWFTTW"

    "'Note that if you recalculate things using a zero windspeed' ... i'll take that as nett windspeed " Nooooo.... When I said "if you recalculate things using a zero windspeed" I really did mean "if you recalculate things using a zero windspeed". If you consider the case of NO WIND BLOWING, you...
  5. Alsee

    Blackbird Land Yacht "DDWFTTW"

    Here's some calculations showing how the cart works. Start with the cart going 30 meters per second to the left, and a wind at 20 meters per second to the left. So the cart is going downwind, faster than the wind. The cart sees an apparent headwind of 10 meters per second. Now we put a load on...

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