your completely right, and sorry i shoulda been more clear, by 'playing around' i meant computer modeling [fluid dynamics or complexity, etc...]
john fisher <[EMAIL PROTECTED]> wrote: well Dale, I am only passing on the wisdom of others, plus a little observation, so take it FWIW. I think experimentation is great, and everybody should get out there and build things. For instance, I've always wanted to try to make a poor-mans wind tunnel out of a trailer, as I mentioned above. But I am aware that without a rolling road, controlled conditions, ability to instrument the airflow, lean the bike, and some good experience, the data would be very rough. Look, its basically impossible to get an accurate, repeatable, dyno reading on a sportbike without $100k in equipment, and thats a much simpler problem. at speeds somewhere between 30 and 50 mph, drag doubles. Its very instructive to look at the graphs used by the LSR guys. They can get 1000 hp up to say 250 mph ( just pulling numbers out of air) but 300 mph takes another 1000. Dragsters are another good source of data. Also HPV racers ( human powered vehicle) So my rule-of-thumb for *my* uses is keep it below 50 mph and give it a nominally electrathon shaped body ( like Aptera for instance) without spending a lot of money. Weight reduction is more important to me since I am looking at a city-vehicle. If I were to scale up to a highway-capable vehicle, I'd probably just copy the Aptera, which is more or less like a modern composite sport plane in shape. But none of that applies to 2 wheel bikes, if thats what you are contemplating. So why am I saying all this ( aside from being a long-winded pedant)? You can fool around with tassels and vortex breakers and belly-pans and what not, but if you don't have a way of checking for improvement ( 1/4 mile time, LSR speed, lap time, wind tunnel ) you'll never know whether you made a difference. BTW Paul is correct about Bernoulli's law and aero lift. Almost everybody, including some NASA websites, have it wrong. Apparently this is well known among pilots, but not so well known among Physics profs. Leather bags, chaps, tassels, soup-bowl helmets, and loud pipes are well known to increase your hp quite a lot. Just not your vee-twin power ;>) dale henderson wrote: > i would like to learn more about how to reduce drag though, for example i've > been toying with the idea of studying effects of tassels on the rear of a > bike. i would like to know if having a series of tassels on the rear would break up the air and thus reduce drag? since i'm more of a chopper fellow wearing a leather jacket with tassels and a seat and saddle bags with tassels would be a simple addition. > > and is there any data on the effects of wind shields on bikes? angles, sizes? > maybe vetter knows? > > harry Albuquerque, NM http://geocities.com/hendersonmotorcycles/blog.html http://www.austinev.org/evalbum/1179 http://geocities.com/solarcookingman --------------------------------- Looking for last minute shopping deals? Find them fast with Yahoo! Search.
