Bowling aerodynamic and rolling hp calculator

[jim reed]

Hello,

My first post on the forum. Has anyone used the Bowling aerodynamic calculator? Does anyone know how close it's prediction have been with real world experience at Bonneville or elsewhere? I wrote a series of articles some years ago for a bike mag on the subject of aero most of which was based on work done by Kevin Cooper for CanAm up in Canada at the gov't low speed tunnel. Using the math he introduced me to the Bowling calculator seems to produce results very close to Cooper's. Bob Barker who rode the bike and was the head engineer at the factory on the project said the Cooper predictions came very close to the speeds they actually acheived with their rotary valve 125 mps bike in setting the record. I talked to Cooper not long ago and his feelings about the fairings used on sportbikes and even GP bikes was that they are pretty much a waste of time. I know that back in the 90's when I did the article for the mag a friend and I ran his CBR600 Honda at Maxton and found the bike significantly faster without it's fairing but with stock seat. We changed the seat to one we made based on Cooper's suggestions with no fairing and it was significantly faster than the faired bike and the naked bike with the stock seat. We never got back to Maxton to run the bike with a CanAm style LSR fairing. Should have been quite fast I suspect.

regards, Jimmy Reed

[Rex Schimmer]

Jimmy,
I "Googled" Bowling Aerodynamics and did get a page that would calculate hp but you needed to know the frontal area and the coefficient of drag for your object. Is this the one?? http://www.bgsoflex.com/aero.html

Looking at what it does there are some nice features, it calculates the hp for rolling resistance and also takes into account the air temp and pressure.

Rex

[JonAmo]

http://www.landracing.com/forum/index.php/topic,3720.0.html

I did that formula based on the magazine article.

I have the nomograph sitting in front of me, very close to real world with Don Vesco's stuff and the MSA Lakester.

Jon

[jim reed]

Hello,

thanks for the input. pretty much the same conclusions I came to.

regards, jim

[ChrisLenahan]

I have been trying to find what issues those articles were in but haven't had any luck.  I can remeber reading them at the time and they stuck with me but it would be good to be able to read them again. 

[jim reed]

I've got copies if you want them. Just send me your address and I'll snail them to you.

jim

[sabat]

I'm not sure which bikes you're talking about, but most folks lose 10-15 mph when the fairings are removed. That is my experience on a ZX10 and a Hayabusa.

[jim reed]

The bike we ran was a Honda CBr 600 1996 if memory serves. The new Suz and Kaw big bikes have vastly improved aero over the past machines as well as current supebikes. I would like to know what the cda is for a current Hyabusa and ZX-14. Anybody know? Back in the TZ days a TZ-350 From a French team went 175 at SPA during the GP weekend with aero much like the CanAm lsr bike. Vesco told me that when he installed his fairing and seat on a TR2 350 Yam that it immediately went 10+ miles an hour faster. It was derived from the old Harley fairing that I think was developed at Cal Tech.  Back in the days when Todd henning was racing his vintage twin shock TZ-350/R-5 against FZR-400s and EX 500s in AMACCS racing I talked him into installing a Vesco fairing and seat. What had been a fairly even battle became a no contest at Daytona. He just walked away. His competators were faired using typical fairings of the day. They were so pissed they took his win from him claiming the bike was a TZ. Fortunately I got a parts book and showed them the cases and frame were R-5 street items. They didn't know the TZ parts would fit the old street twin. They gave him his points but not the trophy if memory serves. This was back in the Rodger Edmondson days. Not bad for a 25 yr old twin shock bike with wire wheels, treaded tires and cast iron/steel brakes attached to 35 mm forks. Can't remember the year but a TZ-750A went 196 at Bonneville with a CanAm style set up. It had 4.5 sq ft frontal area and certainly no more than 140hp (at sea level). I think it ran the TZ-350 cylinders (700cc). Did Gutherie ever go 200 on one of his TZ-750s?

[sabat]

He did, I think it was in 1992.

Jon Amo provided the drag and frontal area values of the Busa and ZX12 here;

http://www.landracing.com/formula/nomograph.htm

The Busa is the slipperiest so far of any stock bodywork.