Fastest Isle of Man Commando?
- Thread starter highdesert
- Start date
- Status
xbacksideslider
VIP MEMBER
- Joined
- Aug 19, 2010
- Messages
- 1,967
Notice how wide that fairing is; that shape was atypical; most bikes, especially the Japanese, had narrow fairings which left elbows and shoulders in the wind.
Hortons Norton
VIP MEMBER
- Joined
- Oct 12, 2007
- Messages
- 2,036
In fact Buell won the AMA pro racing championshp series in 2009 and the motor was 1125, But most people don't know this as we have just heard! But the h.p. was very close indeed to all the inline fours. :wink:
- Joined
- Oct 19, 2005
- Messages
- 18,978
In Dunstall Tech Note he compared fairings, basically narrow vs wide to find the wider one hide pilot better for less resistance. They also made front of fairing flat to pile air up for a different sort of streamlining over round tube or dirtier cover shapes. Rolle had parties of friends come by to poke press and tug him into the most laid out of the wind posture so he'd know what to practice w/o a wind tunnel.
- Joined
- Oct 19, 2005
- Messages
- 18,978
- Joined
- Sep 26, 2009
- Messages
- 2,210
Just think if Duncan and 10 other racers are now going faster with the LANSDOWNE dampers ,what would Peter Williams have laped at with precise front end controll the new cartridges offer :?: Mayby another 5 mph :?:
100 bhp per litre for a four stroke push rod, two valver is about the limit, 200 bhp from a two stoke multi is the norm , i watched the "Flying Fin" on a 350 Yam leave the 750s for dead at Brands in the early seventies, Jarno was a exceptional rider, a great loss . and young .
100 bhp per litre for a four stroke push rod, two valver is about the limit, 200 bhp from a two stoke multi is the norm , i watched the "Flying Fin" on a 350 Yam leave the 750s for dead at Brands in the early seventies, Jarno was a exceptional rider, a great loss . and young .
Peter Williams spent hours in the wind tunnel testing the aerodynamics.....and I men HE spent the time in there, sitting on the bike, having to hold his racing crouch for 5 minutes after the fans had stopped to enable the sensors to normalise again. The drag coefficient was 0.39
I thought this was common knowledge, but again, I'm only interested in racing Commandos, but definitely well known to most people who have met and spoken at length with Peter. He was following Moto Guzzis formula from the 50s, minimising frontal area and reducing drag.
I thought this was common knowledge, but again, I'm only interested in racing Commandos, but definitely well known to most people who have met and spoken at length with Peter. He was following Moto Guzzis formula from the 50s, minimising frontal area and reducing drag.
This is part of a story from NZ on the Britbike Forum, when Peter Williams was invited to Pukekohe.
"Peters influence on the bike was very wide but he was especially happy about the results in reducing drag. He talked about testing in wind tunnels, working out precise rider position. He said he could feel when he was in the right place because his back would go cold from the wind flow. They took the numbers and patches off the backs of their leathers to smooth the surface. The drag coefficient on the 1970s monocoque has only been bettered recently by GP bikes. They had to do all this because they were so far down on hp."
The MIRA (Motor Industry Research Association) wind tunnel was opened in 1960. This would have been the most likely facility to have been used.
xbacksideslider has it right. The JPN fairing was quite unusual compared with the competition, and didn't come about by happy coincidence. The shape of the tail fairing was also important in smoothing out the air flow at the rear of the bike.
"Peters influence on the bike was very wide but he was especially happy about the results in reducing drag. He talked about testing in wind tunnels, working out precise rider position. He said he could feel when he was in the right place because his back would go cold from the wind flow. They took the numbers and patches off the backs of their leathers to smooth the surface. The drag coefficient on the 1970s monocoque has only been bettered recently by GP bikes. They had to do all this because they were so far down on hp."
The MIRA (Motor Industry Research Association) wind tunnel was opened in 1960. This would have been the most likely facility to have been used.
xbacksideslider has it right. The JPN fairing was quite unusual compared with the competition, and didn't come about by happy coincidence. The shape of the tail fairing was also important in smoothing out the air flow at the rear of the bike.
lcrken
VIP MEMBER
- Joined
- Mar 15, 2009
- Messages
- 4,983
swooshdave said:
No pics, but I know they used an extended sleeve gear to fit the extra bearings. Norrman White showed me the factory drawing for it when I visited his shop back in the '80s. When Norton closed down the facility at Andover, they left a lot of drawings, including this one, which Norman salvaged. I don't recall all the details, but the drawing showed a sleeve gear with a longer extension than stock. My failing memory also says that there was a double row ball bearing in place of the standard sleeve gear bearing, but I can't be absolutely positive of that. I assume the outrigger bearing was retained in the inner half of the custom primary case they used. As I recall, they used a double row primary chain, not the Commando triple.
More primary trivia. My friend Mick Ofield, who used to work for Norton, said the race shop had experimented with belt drives back then, but found them not reliable enough. Belt drive technology has greatly improved since then.
Ken
Interesting chat about aerodynamics.
Can't say I've seen much of that in print before.
Worth pointing out though that Nortons best result at Daytona was 4th in 1972, with Phil Read as pilot. Slim version of fairing, it must be noted....
P.S. Although the early 1950s Manx WINS at Daytona must be noted.
Before they banned Manx and Inters and OHC motors....
Can't say I've seen much of that in print before.
Worth pointing out though that Nortons best result at Daytona was 4th in 1972, with Phil Read as pilot. Slim version of fairing, it must be noted....
P.S. Although the early 1950s Manx WINS at Daytona must be noted.
Before they banned Manx and Inters and OHC motors....
- Joined
- Jun 17, 2009
- Messages
- 642
Yes, and in fact Read's 4th place finish was the highest finish of any 4 stroke in that race, including the more powerful Triumph/BSA triples.
Read was at one point the outright leader at Daytona that year.
Read was at one point the outright leader at Daytona that year.
- Joined
- Oct 19, 2005
- Messages
- 18,978
Dunstall race notes on last page has head on photo of narrow fairing that exposed bar ends and wider one that covered bar end and stated by electronic eye speed test the wider beat the lower for better air 'penetration'. Don't know more than that to apply to the Daytona results. I'm going big and bulbous on Peel, but mostly for weather protection.
Does anyone have the I.o.M. speed trap figures?
It would be interesting to compare the F 750 Norton with the G.P. 500 Honda, since they both did similar average speeds, one known for good handling/steering/roadholding, & the other, not.
From Cycle Australia May `74 P22,
A list of the Daytona 200 F750 trap speeds;
1, H. Kanaya, Korea, Yamaha TZ 750, 307.01 kmh.
2, Y. Du Hamel, Canada, Kawasaki H2R 750, 298.11 kmh.
3, G. Romero, U.S.A., Yamaha TZ 750, 294.11 kmh.
4, D. Castro, U.S.A., Yamaha TZ 750, 280.14 kmh.
5, B. Sheene, U.K., Suzuki TR 750, 275.86 kmh.
For the imperialist hold-outs, a km is `bout 5/8ths of mile..~1.6:1 ratio..
It would be interesting to compare the F 750 Norton with the G.P. 500 Honda, since they both did similar average speeds, one known for good handling/steering/roadholding, & the other, not.
From Cycle Australia May `74 P22,
A list of the Daytona 200 F750 trap speeds;
1, H. Kanaya, Korea, Yamaha TZ 750, 307.01 kmh.
2, Y. Du Hamel, Canada, Kawasaki H2R 750, 298.11 kmh.
3, G. Romero, U.S.A., Yamaha TZ 750, 294.11 kmh.
4, D. Castro, U.S.A., Yamaha TZ 750, 280.14 kmh.
5, B. Sheene, U.K., Suzuki TR 750, 275.86 kmh.
For the imperialist hold-outs, a km is `bout 5/8ths of mile..~1.6:1 ratio..
- Status