coeffecient of friction

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David Leikvold
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gator

Post by David Leikvold » Mon Dec 22, 2008 8:44 pm

Yep, they're called Gators or Alligators. The originals used a 650cc Honda chooky single, now the newer version uses an S&S V twin. If my memory serves me correctly (and it rarely does these days) 3 wheelers are regarded as bikes. If you're looking for traction how about running 2 rear wheels on parallel but independent swing arms (a bit like a Dodge Tomahawk) and have 2 chain drives. Might as well be completely unconventional, because let's face it, it doesn't make sense to do everything the same as everyone else and then expect to be faster!
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Stayt`ie
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Post by Stayt`ie » Mon Dec 22, 2008 10:49 pm

Gary, i dont think the mighty Hayabusa has reached its limits yet,, yeah sure thay have stagnated, better still thay have been in a comfort zone, no one has pushed them to go faster,,,, however after Richards effot this year, i will be surprised if in 2009 we dont see John N come out faster, not sure what Jason M`s plans are, but i recon he wont be sitting around. I know Richards bike is capable of faster speeds, i recon we are going to see a resurgance in ultimate sit on bike performances,,, bring it on :D
First Australian to ride a motorcycle over 200mph at Bonneville,,,

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Greg Watters
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Post by Greg Watters » Tue Dec 23, 2008 9:16 am

My understanding of wings is there subject to cross winds, in a plane you would crab a bit and adjust the tail or wing to suit... on a bike a greater force on one side will lean or steer you.

I think tire technology is holding the bikes at the current point,

David Leikvold
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worms

Post by David Leikvold » Tue Dec 23, 2008 10:56 pm

Yes, wings on bikes could be a real can of worms. If a wing was mounted high, i.e. any higher than the rider, the sideplates would certainly exert unwanted leverage in a cross wind and make the bike lean just when you didn't need the excitement. And the rider would spoil the airflow so much that the wing would hardly work anyway. So that would suggest that any wings should be placed in clean air on existing body panels so as not to increase the area exposed to crosswinds and to improve the efficiency of the wings.
If it was a normal configuration bike the best idea would be to have one on each side of the fairings in front of the rider's shins. That way they'll never touch the ground unless the bike has already crashed, they don't increase the surface area exposed to cross winds and they're about midway along the bike so the downforce generated would push on each tyre about the same. You just have to make sure they were set at identical angles or they would steer the bike to one side. And if they were very strong they might protect parts of the bike better in a big crash. I'm not saying this is necessarily a winner of an idea, it's just something a few people might like to ponder in the shed one night when there's nothing else to do.
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Greg Watters
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Post by Greg Watters » Wed Dec 24, 2008 9:01 am

Even in that position the force on each would have to be exactly the same to not affect handling, not very likely in real world conditions,
quite often during a run a gust will move you around , over the length of the track its possable for a breeze to come from one direction at one end and another direction near the 5 mile as the nearby ranges influence airflow across the lake.

Tiger racing have bolt on wings available, not sure i would want to try either of them, (but i do like his chainguard and bellypan)

David Leikvold
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Post by David Leikvold » Wed Dec 24, 2008 10:19 am

I couldn't find the wings, except for a tiny one mounted on the pillion fairing on a customer bike. The belly pans are good and some of the full fairing kits look really slick, especially Seldom Seen Slim's. Nobody seems to move the footpegs from their original positions. Is there a rule that says you can't? That might make it easier to get lower down on the bike especially if the fuel tanks were flattened to get the rider's rib cage lower.
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Greg Watters
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Post by Greg Watters » Wed Dec 24, 2008 12:02 pm

There used to be canard wings mounting on the front forks too
i think the aim was improved traction on front and rear :?
Lower fuel tank is good,
I actually forgot which bike i was on during one run at Bonneville and went for the rear pegs i have when my bike is in drag trim, ...bloody hard to bring your feet forward again at 180mph :oops:

Footpegs are moved around a bit for personal fit but not far from std position, anything else would need a fairing mod , and i suspect thin ankles are easier to fit out of the wind than thighs, and toes down is more surface area again ???

hawkwind racing
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Post by hawkwind racing » Thu Jan 01, 2009 4:28 pm

I have put together some figures to demonstrate that at least for motorcycles ,traction is by far our greatest challenge ( with the existing rules ) ,also for comparison I have added some figures for a roadster which has a similar Cd to a P/S bike ,both rely almost exclusivly on brute HP for top speed .
roadster A (frontal area) 21.5 ft2 Cd 0.75
P/S bike A " " 6.1 " Cd 0.6
Naked bike A " " 5 " Cd 0.75
drag in pounds, power in HP thrust in pound force & weight in pounds
CASE # 1 200mph

------- roadster----------- naked bike--------------- P/s bike

drag 1573 -------------- 366 --------------- 357
H.P 880 ---------------- 205 -------------- 200
thrust 1650 ---------------- 384 --------------- 375
weight 2750 ---------------- 641---------------- 625

CASE # 2 250 MPH

drag 2458 -------------- 572 --------------- 558
H.P. 1718 -------------- 400---------------- 390
thrust 2577 -------------- 600 ---------------- 585
weight 4295 -------------- 1000 --------------- 975

from the above figures we can see that trying to get 1000 LBS of wieght over the back tyre of a bike is next to impossible both from a physical perspective as well as a tyre loading perspective , I spose getting the weight on the roadster is not easy as well ,but nowhere as hard as for the bike , getting the power for the bikes is piss easy ,though much harder especially for the higher speeds for the roadster
IMHO I suspect that the bikes have just about reached there limits ,unless tyre technology advances ( or switching to landspeed eagles ) then its working out how to get half a ton of lead over the back wheel OR allowing much more radical streamlining , I think its time to do a special construction with ductbin & boat tail and run time only as a pre cursor to allowing radical streamlining to special construction on a perminant basis :D
cheers
fastest busa in Captains flat pop. 200

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internetscooter
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Post by internetscooter » Thu Jan 01, 2009 4:47 pm

Tony Foale's book (http://www.tonyfoale.com/) has a bit on wings, in theory it is possible but you'd need to position things correctly and have the wing tilt to adapt to forces.

He says Colin Lyster's "wing" bike, has the wing too high and to the rear.

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