koz
Expert Class
Posts: 304
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posted May 31, 2002 03:48 AM
Aerodynamics
In the wind tunnel test about a year ago, I'd like to know the ranking for the 12, busa, and GSXR. From what I can remember it was the GSXR-1st, Busa-2nd, 12-3rd. Can anyone verify that. If that is so, there is a GSXR1000 from Lee's with over 200HP that made a 193mph top speed run. To me that kinda shoots holes through the wind tunnel results. When a 12 with 170HP runs 192mph. More aerodynamic my ASS!
Koz
  
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bagster
Zone Head
Posts: 630
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posted May 31, 2002 07:41 AM
test method
does anyone here know exactly HOW they measure the drag on bikes in a wind tunnel?
I have seen shows on testing airflow with smoke and i know they hook sensors up to different areas on the bike to check high and low pressure zones.
but do they actually put the bike on a level roller bearing plate and hook it up to some sensor to see how much force is pulling the bike back at different speeds?
of course my way would be the "hack n slash" engineering way. ;-)
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oldkawboy
Needs a job
Posts: 2125
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posted May 31, 2002 09:14 AM
Hey Koz,
Glad to hear someone else questioning the same thing as I have. The June 2001 issue of Sport Rider has the article and I will quote, "With an obviously smaller frontal area than both the Hayabusa and ZX12R, the GSXR produced less drag than the ZX12R, but still more than the Hayabusa" " The winner of this wind tunnel shootout is the Hayabusa"
CDA (ft2)
BUSA 3.37
GSXR 3.49
ZX12 3.67
Back to the real world....This past March we where at Maxton and Lee brought the 200hp GSXR. We ran back to back under the same conditions, he had 10 hp on me, is smaller and a much better rider. I ran a best of 202 and his best was 193, over all the runs I averaged 6-8 more mph. I'm not degrading him or his bike but it sure gets old hearing about how slow these heavy, un-aerodynamic 12's are! There was not any faster normally aspirated 'Busas there that could run with Lee. One more quote and I'll shut up!
"The Suzuki Hayabusa deserves to keep the title as the world's fastest motorcycle" Yawn...
Dan
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PaulVincent
Expert Class
Posts: 135
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posted May 31, 2002 09:54 AM
 Edited By: PaulVincent on 31 May 2002 21:03
koz and okb, I have repeatedly written on this site as well as Labusas that the real world and the wind tunnel are not the same. The last two times I wrote, I cited evidence/results from the auto world (F1). Jaguar is having a difficult time of it, and part of the equation is that wind tunnel testing doesn't add up to real world results. I also cited evidence from the aeronautical world. That both military and commercial aircraft don't always produce the numbers that cd. and wind tunnel testing would predict. I think that this is a case much like (but far more esoteric than) the difficulty that the 12 provided in its needing proper break in and oil level to produce its peak results. And if the magazine "experts" had a hard time accepting the fact that the 12 was in need of a lengthy break in and proper oil fill, how could they possibly consider, let alone conserve, the idea that aeros are more difficult to acertain than conventional wisdom would have us believe? And yes, the second I read of the 201.6 hp GSXR1040's terminal speed, I knew it was additional evidence that aeros are more than the experts understand.
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your car is slow
Needs a job
Fuck Nitrous...Got Boost?
Posts: 4089
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posted May 31, 2002 10:04 AM
having ridden a Gixxer1k at around 150mph...there is no way in hell that bike gives the wind protection required to beat out the 12 in aerodynamics "With a Rider".
perhaps with noone on the bike...or a freaking Fraggle size mutant rider on it.
I damn near thought I was going to fly off that bike at speeds that high.
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Do not taunt happy fun ball!
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Koz
Expert Class
Posts: 304
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posted May 31, 2002 11:26 AM
My post was aimed at the claims that the 12 needs more HP to achieve the same speed of a busa/gixxer. If you use the Lee's gixxer (with 200+ HP), that went 193MPH, it PROVES that all those wind tunnel tests are NOT acurate.
OldKawboy - Did you do any testing with different shields? (Double Bubble - Sport Tourer)
I know it adds frontal area but, I'm wondering if it may help by making a bigger/cleaner hole for bigger riders. I read your comment about you modding the seat to get out of the wind. If you have tested other shields (Or heard of someone else), how much effect or MPH would you gain or lose. The reason I ask is, take a look at a road racing/GP bike, their shields are pretty big. I know they're not concerned about top speed but they reach some high speeds down the straights. I do alot of high speed street(Highway) riding (cruising at a buck 20/30 and short blasts to peak). I wouldn't think of taking my sport tourer shield off, it's the difference of being able to see and enjoy the speed (And I fucken ENJOY speed).
Koz
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entropy
Moderator
Posts: 8671
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posted May 31, 2002 11:28 AM
Edited By: entropy on 31 May 2002 14:43
AEROS???? ZX12 = Busa!!!!!
I have posted this before, but let's do it again.
same hp
Pappabusa's Busa (1397) and my ZX12 (1361) were both dynoed at 194-5hp SAE,
same size riders
John and I are both 6'3" or so 230lb suited or very close to it.
optimal gearing
both of us had many top end tests to get optimum gearing; he had an onboard Halmeter, had bike tuned for top end
same conditions
we made multiple passes on same day, same 3 mi straight, same direction, within 15 min
same results on GPS's
201mph; neither of us could get 1 mph more
Conclusion
for people 6'3", 230#, with 195hp:
Busa aeros = 12 aeros
Am I disappointed? Ecstatic? Bored?
none of the above. I am just VERY happy to have achieved 200mph and so was John 
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted May 31, 2002 12:12 PM
Wind tunnel testing.
The testing of the aeros that I've seen are very uncontrolled.
Rider position is key. Was there even a rider on board?
Not in one of the tests I read. One of the other tests never said anything about it.
Its all as worthless as everything else they try to test.
Just like HotRod and CarCraft are to cars... Cycleworld and Motorcycliest are to bikes....its all bullshit to entertain the kids.
I can hardly stand to even open those magazenes anymore.
If my buddy didnt drop them off once in a while I'd never even see them.
As for windtunnel testing... I dont know how drag is read. But I can find out.
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frEEk
Administrator
ummm... yeah
Posts: 9660
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posted May 31, 2002 12:17 PM
here's another (earlier i think) aeros test from Cycle Canada magazine. pretty similar results. This one used a gsxr750 as the 1k had not come out yet. results:
CDA (m2), rider crouched
Busa: .313
GSXR: .324
12R: .341
i imagine the 1k is almost identical. such a large difference in aeros makes u wonder why the bikes are often so evenly matched, as in the case posted above. a couple clues come in the cycle canada article. for one, they mention the big single sided can of the the 12 is pretty bad. so the standard aftermarket version shoudl help a bunch. going to flushmounts should help a bit (the article mentioned the integrated signals of the busa).
but what bothers me most is the suggestion i'v read a couple times that it doesnt matter what wind speed u perform the wind tunnel tests at. this is an argument thats been bantered about before. i dont buy it. i dont believe the aerodynamics (dynamic being the key word here) are going to be static. at certain speeds eddies could reach a particular diameter that begines to interfere with adjacent phenomenon for example. the frontal shockwave grows wider as speed increases too if i'm not mistaken, thereby changing the forces acting on everything behind it. now ranted, i gots no education in aeros, this is jsut from what little i have observed from tv programs and the like. in any case, seems that most of these wind tunnel test were done at around 100mph, and not at closer to 200 as i think they should. this could definitely explain the lack of performance out of the 200hp 1k.
course, there is one other major factor that people often overlook, and it is also mentioned in the article: rolling resistance. tho a small portion of the equation, this dfoes play a part. i would guess that this doesnt vary much from bike to bike, but perhaps it does. do dynos take rolling resistance into consideration? given that the rear wheel at least ir turning, it may consider it to some ddegree. but given the amount of brake drag on the front (esp with aftermarket pads), that could make a big diff. obviously a wind tunnel cares nothing about rolling resistance. i guess the only way u coudl measure real work results is put an inline dyno (dont remember what the correct term for them is) on the wheel, measuring the actual power transfered thru the sprocket. u could also place a simpler force meter such that the forward force on the axle is measured.
course, at the end of the day, the test of the 195hp bikes says almost all that needs to be said. the rear wheel puts out the same power, and all moving factors combined (aeros, front wheel drag, etc) lead to approx the same results. my only concern with that scenario is the lack of the riders switching bikes. the slight difference of their crouches or riding gear could be all the difference.
hey, they'r fast. what more do ya want? 
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frEEk
Administrator
ummm... yeah
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posted May 31, 2002 02:32 PM
btw, just calculated the conversions for the two magazines' tests, and they are identical.
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dougmeyer
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moderated
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posted May 31, 2002 03:22 PM
My fifty cents.
Drag in a wind tunnel is shown in pounds of load measured by electronic load cells. This is basic, very mature technology.
Subsonic aerodynamics is also VERY mature and well explored technology. Most of the work was done in the 30's and 40's when aircraft were subsonic. There are plenty of basic texts that explain most of your questions.
Subsonic aerodynamics "scales" up and down almost perfectly (as does hydrodynamics when designing a boat hull) again this is common, well proven engineering. The use of models is widespread in aircraft, auto, and boat aero testing (Sorry, Freek, you may not "buy it" but that's opinion, which differs quite a bit from provable scientific fact.
The Bosch Handbook of Automotive Engineering lists the rolling coefficient of resistance of a properly inflated bias ply auto tire on pavement at .015. By comparison this same value of a steel wheel on a rail is .001. This becomes a component of the overall coefficient of drag of the entire motorcycle which is about .4 to .6. As you can see, it's a small part of the overall Cd.
I think (I KNOW actually) the riders position is vastly underestimated in all these discussions and evaluations. The bottom line on a high speed motorcycle is FRONTAL AREA and the rider has a lot to do with this. Here's what I think happens. You take a given rider and put him on a given motorcycle-he crouches and you measure drag. Now take him and put him on a smaller bike, which "riderless" has a cmaller Cd. But our rider can't crouch the same on the smaller bike. His back is higher, his elbows are out a little. Now the smaller bike shows a worse Cd. The bigger one a better Cd. My point is, every rider and a given bike gives a different Cd. I'm glad to be seeing all you guys running Maxton. You're starting to see the variations between different riders on the same bike and the same setup on different runs. You are finding that the bike with most power may not always be going the fastest.
Doug
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It's not that I think you're dumb, it's just that so much of what you know isn't true....
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frEEk
Administrator
ummm... yeah
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posted May 31, 2002 03:56 PM
thx for the educated post doug. i'm pretty surprised about the scaling of aeros, but given that i am an engineer, i'm not gonna dismiss the practice of over half a decade of science given that the test in cycle canada used the same rider on all the bikes, i think it's fair to say that their numbers are solid and the identical speeds of the 195hp brothers were due to all the other factors, predominantly the riders.
any thoughts on the effect or removing turn signals, mirrors and the ssmaller can? did u play with any of this on the top speed runs muzzys did a year or so back?
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oldkawboy
Needs a job
Posts: 2125
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posted May 31, 2002 07:39 PM
Koz,
I talked with Chip Ellis (Kawasakis Funny Bike rider) after he came back from Maxton last year on his 12. He did try the Double Bubble and stock shield back to back with no difference.
For the record(s), Chip ran 203 and Bergie went 202 at Maxton and both of their 12's had less than 200hp. Gotta love those Kawasakis!!!
I really appreciate all the input in this interesting subject.
Dan
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