Motorcycle CFD Reduction Tips

[donpearsall]

That's an amazing bike Whizbang. Good work. By looking at the frontal view, you can see that your legs and feet will provide the most un-streamlined and draggy part of the bike. If you can make that lower fairing to come back more and go out a little wider then the legs will be in the slipstream shadow. I think it will reduce the total drag although it will be wider.
How fast is it expected to go? Tell us more about the bike and the build.
Don

[WhizzbangK.C.]

Thanks! 

We're not really sure how fast it'll go. We're fairly confident it'll go over 100, and we'll be very happy with that, and ecstatic if it'll give us 120, given that we're working with an old, stock engine. The record in the class is well over 150 right now, and we're sure that's out of reach, with the stock engine at least. This is more or less a learning exercise for us right now, and we're having a real good time doing it.

As far as more info, check out the XR500 post in Build Diaries. Lots of pics and descriptions of what we've done so far.

[narider]

Jon,
Unfortunatley for Production rules, this is yet another great idea that is not allowed

And although some have found out how to alleviate the radiator and aero concerns with the use of a v-twin plant, most of us have at the same time alleviated the possibility of big speeds by doing so. 

Larry's findings are the same that Dave had found in his wind tunnel testing some years back. So along with the speeds and longevity they've both accomplished; these being the two fastest NA teams of their time certainly adds merit to anyone considering this tip.

See you very soon,
Todd

[Seldom Seen Slim]

Todd, I was thinking farther ahead -- to the 250T and the 12N.  I know that we couldn't do the radiator block-off thing on the 15R.

See you soon.

[narider]

I know you knew that on the 15... it was moreso words for others that may have been thinking differently.

I'll put it on the whiteboard for when we get good enough temp data on the other bikes.

If it would show safe on a dyno simulation run we may consider a variation at Maxton first, but truthfully I'm not big on cutting cooling on a non NA motor until I see the numbers... especially on a long course nitrous bike. 
Todd

[kiwi]

Regarding the new rule for special construction, partial streamlining, tail sections  (7.G.11). Does this mean that the tail section can now completely enclose the rear wheel and tyre except for the bottom 4" ?

[Commuta_Busa]

I've been wondering the same thing if you reshape the tail section...

Regarding the new rule for special construction, partial streamlining, tail sections  (7.G.11). Does this mean that the tail section can now completely enclose the rear wheel and tyre except for the bottom 4" ?

[joea]

as always.........CALL THE TECH FOLKS FOR CLARIFICATIONS....

as i did...........

even with my own understanding........and interpretation.....

there is always room for differences.......

its like reading the bible and telling someone what a passage
meant...........

Van Butler took my call with vigor and enthusiasm...!!!!!

and Tom Evans is the MAIN interpreter...and enforcer.....and I
for one want to say...

THANK YOU VAN BUTLER AND TOM EVANS........you guys mean
so much to our sport right now.....KUDOS to you guys for your
dedication....!!!!!!!!


Joe

[oz]

Ive got a big pot of dimple finish GOLF BALL PAINT,GOLF BALLS,GOLF BALLS,GOLF BALLS,
I got told off last time I mentioned them,
I do think that the only real way of testing aerodynamics is wind tunnel testing.
some early faired bikes actually had more drag than there un faired counter parts,narrow/small/pointy frontal area isnt always the way to go either.
love it or hate it the Hayabusa is by and large the most slippy through the air stock motorcycle personaly I think they look awful and if you had asked me 15or so years ago what an aerodynamic bike would look like it certainly wouldnt have been a Busa but the Japanese invested a load of time and god knows how much money making it that way
Sometimes adding random lumps and bumps in the most unusuall places can have a huge effect on aerodynamics but without a tunnel its very hit and miss.
ps.Ignore the Golf Ball bit but apparently someone mentions it every year, and its about a year since I mentioned it last time!!

Ignore me I am bored and I want to go to Bonneville NOW!!!!