Blowhards Sailing Downwind
in [Basics]
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From: Joe on 31 Jul 2010 20:53 There sure seems to be a lot of people in need of remedial reading-for-content involved in the thread about sailing downwind. First of all, in all the posts that I can stand to read, John Larkin is NOT saying that his wind-propelled object would move FASTER than the tailwind, just that it WOULD move in the direction of the tailwind. Second, some people seem to misinterpret John's comments and argue against their erroneous interpretation of John's comment, or seem to say (*seem to*, because some of their rants are not very coherent) that an object cannot be wind propelled at all by a tailwind, regardless of the contrivance (e.g., windmill driving a gearbox). Third, I don't know why John hasn't set these people straight, nor do I understand why this thread has forked in two: Direct Downwind Faster Than the Wind (DDWFTTW) vs Direct Downwind NOT Faster Than the Wind (ddwNfttw). Those that are arguing against ddwNfttw probably would argue that an electrical generator cannot supply the electricity that powers its own field ELECTROmagnets. Sheesh! --- Joe
From: Joe on 31 Jul 2010 21:12 In article <none-3107101753220001(a)dialup-4.231.172.30.dial1.losangeles1.level3.net>, none(a)given.now (Joe) wrote: > There sure seems to be a lot of people in need of remedial > reading-for-content involved in the thread about sailing downwind. > > First of all, in all the posts that I can stand to read, John Larkin is > NOT saying that his wind-propelled object would move FASTER than the > tailwind, just that it WOULD move in the direction of the tailwind. > > Second, some people seem to misinterpret John's comments and argue against > their erroneous interpretation of John's comment, or seem to say (*seem > to*, because some of their rants are not very coherent) that an object > cannot be wind propelled at all by a tailwind, regardless of the > contrivance (e.g., windmill driving a gearbox). > > Third, I don't know why John hasn't set these people straight, nor do I > understand why this thread has forked in two: > > Direct Downwind Faster Than the Wind (DDWFTTW) > > vs > > Direct Downwind NOT Faster Than the Wind (ddwNfttw). > > Those that are arguing against ddwNfttw probably would argue that an > electrical generator cannot supply the electricity that powers its own > field ELECTROmagnets. > > Sheesh! > > --- Joe Gulp! I read too much of that thread and became addled. What John said is so amazingly simple and obvious, and the people that were arguing against it so confused, that it seems to have rubbed off on me. John merely said that an object could be wind propelled directly into a headwind by way of say, a windmill turning a gearbox and some wheels. As long as the widmill is allowed to orient itself into the wind (they usually swivel) the wind powered wheeled vehicle can go in *any* direction. --- Joe
From: John Larkin on 1 Aug 2010 02:27 On Sat, 31 Jul 2010 18:12:26 -0700, none(a)given.now (Joe) wrote: >In article ><none-3107101753220001(a)dialup-4.231.172.30.dial1.losangeles1.level3.net>, >none(a)given.now (Joe) wrote: > >> There sure seems to be a lot of people in need of remedial >> reading-for-content involved in the thread about sailing downwind. >> >> First of all, in all the posts that I can stand to read, John Larkin is >> NOT saying that his wind-propelled object would move FASTER than the >> tailwind, just that it WOULD move in the direction of the tailwind. >> >> Second, some people seem to misinterpret John's comments and argue against >> their erroneous interpretation of John's comment, or seem to say (*seem >> to*, because some of their rants are not very coherent) that an object >> cannot be wind propelled at all by a tailwind, regardless of the >> contrivance (e.g., windmill driving a gearbox). >> >> Third, I don't know why John hasn't set these people straight, nor do I >> understand why this thread has forked in two: >> >> Direct Downwind Faster Than the Wind (DDWFTTW) >> >> vs >> >> Direct Downwind NOT Faster Than the Wind (ddwNfttw). >> >> Those that are arguing against ddwNfttw probably would argue that an >> electrical generator cannot supply the electricity that powers its own >> field ELECTROmagnets. >> >> Sheesh! >> >> --- Joe > >Gulp! > >I read too much of that thread and became addled. What John said is so >amazingly simple and obvious, and the people that were arguing against it >so confused, that it seems to have rubbed off on me. > >John merely said that an object could be wind propelled directly into a >headwind by way of say, a windmill turning a gearbox and some wheels. Yes, I did say that. It's fairly obvious. What I don't know is how fast it could move windward, and whether it could actually move faster upwind than the wind speed. Apparently people have hit numbers like 60% or some such. The straight downwind, faster than the wind, case probably works too. It is sure counter-intuitive. > >As long as the widmill is allowed to orient itself into the wind (they >usually swivel) the wind powered wheeled vehicle can go in *any* >direction. Yup. John
From: Roger Dewhurst on 10 Aug 2010 22:12 John Larkin wrote: > On Sat, 31 Jul 2010 18:12:26 -0700, none(a)given.now (Joe) wrote: > >> In article >> <none-3107101753220001(a)dialup-4.231.172.30.dial1.losangeles1.level3.net>, >> none(a)given.now (Joe) wrote: >> >>> There sure seems to be a lot of people in need of remedial >>> reading-for-content involved in the thread about sailing downwind. >>> >>> First of all, in all the posts that I can stand to read, John Larkin is >>> NOT saying that his wind-propelled object would move FASTER than the >>> tailwind, just that it WOULD move in the direction of the tailwind. >>> >>> Second, some people seem to misinterpret John's comments and argue against >>> their erroneous interpretation of John's comment, or seem to say (*seem >>> to*, because some of their rants are not very coherent) that an object >>> cannot be wind propelled at all by a tailwind, regardless of the >>> contrivance (e.g., windmill driving a gearbox). >>> >>> Third, I don't know why John hasn't set these people straight, nor do I >>> understand why this thread has forked in two: >>> >>> Direct Downwind Faster Than the Wind (DDWFTTW) >>> >>> vs >>> >>> Direct Downwind NOT Faster Than the Wind (ddwNfttw). >>> >>> Those that are arguing against ddwNfttw probably would argue that an >>> electrical generator cannot supply the electricity that powers its own >>> field ELECTROmagnets. >>> >>> Sheesh! >>> >>> --- Joe >> Gulp! >> >> I read too much of that thread and became addled. What John said is so >> amazingly simple and obvious, and the people that were arguing against it >> so confused, that it seems to have rubbed off on me. >> >> John merely said that an object could be wind propelled directly into a >> headwind by way of say, a windmill turning a gearbox and some wheels. > > Yes, I did say that. It's fairly obvious. What I don't know is how > fast it could move windward, and whether it could actually move faster > upwind than the wind speed. Apparently people have hit numbers like > 60% or some such. > > The straight downwind, faster than the wind, case probably works too. > It is sure counter-intuitive. > >> As long as the widmill is allowed to orient itself into the wind (they >> usually swivel) the wind powered wheeled vehicle can go in *any* >> direction. > > Yup. > > John > Light sailing boats can sail faster than the wind but not downwind or with the wind abaft the beam. They are not reliant on the wind pushing the concave side of the sail but the combined effect of low pressure on the convex side of the sail, (Bernoullis Law) and the centrifugal force of the wind rotating in the concave curve of the sail.
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