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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 1039211 times)

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Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3645 on: September 30, 2020, 02:22:06 PM »
During my early 20's race tires were tried for street racing by some of my friends.  They almost killed themselves so I did not use them.  The problem was lack of grip.

These videos I am watching during lockdown.  They show and discuss race tire vs track temperature vs performance.  My friends probably did not get the tires hot enough to grip.  These racers pre-heat the tires prior to racing and do a warm up lap to get them ready to race.  Some of these videos are in Spanish and most are in English.  The lady doing the commentary is Suzy Perry.  She was one of the first women that presented the races and has been doing it for over 20 years.   

https://www.tokyvideo.com/series/moto-gp-2020-full-race

Offline manta22

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3646 on: September 30, 2020, 07:00:45 PM »
WW;

When I was drag racing my '65 Pontiac GTO, I used M & H Racemaster slicks but one time I was in a hurry and did not replace them at the track with my street tires. They were great on the street until it started to rain. I drove home at 15 mph.... :?
Regards, Neil  Tucson, AZ

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3647 on: October 01, 2020, 11:24:58 PM »
That car must'a been fun to race.  There were a lot of drag strips in the old days.  The tracks were dry in the first five races on those videos and those are what I have watched until now.  They used soft, medium and hard slicks.  Hopefully it will rain for a race and I can see how they set up the tires. 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3648 on: October 19, 2020, 11:24:05 PM »
The featured bike in this article, the John Player Norton, has a fairing that was developed using extensive wind tunnel testing.  Note how it gives the rider good coverage and the trailing surfaces, just before they end, are parallel to the direction of wind flow.   

https://www.motorcycleclassics.com/classic-british-motorcycles/john-player-norton-monocoque-replicas-zmmz13sozbea

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3649 on: October 19, 2020, 11:39:28 PM »
This article shows the current MotoGP fairings.  There is much less coverage and the trailing edges are angled to the wind flow.  This seems like backwards progress from that 1070's Norton.  The new fairings look to be inefficient.  I asked about this during the wind tunnel visit.  The answer was to keep the fairing large so as to give good coverage.  "The fairing is more streamlined then you are" was the answer I remember hearing.

https://www.crash.net/motogp/feature/928481/1/wings-chins-remain-under-stricter-2020-motogp-aero-rules   

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3650 on: October 20, 2020, 10:36:21 PM »
Surface roughness vs smoothness was discussed at the wind tunnel.  The tail section may have a small area of attached flow with a turbulent boundary layer.  Most or all flow will be detached turbulent flow.  No appreciable benefits will be gained by a smooth surface in these conditions.  The rivited plate surface will be used.  It is easy to make and repair or modify and it is light and strong.

F = ma or force equals mass times acceleration.  Reduction in the force to overcome aero drag allows the bike to go faster and this means the mass of air disturbed by the vehicle must be minimized as well as the acceleration of the disturbed air.  Acceleration is a change in air velocity or in the direction of air flow.  Creating a wake vortex or disturbance accelerates air in both velocity and flow direction.  Wake disturbance needs to be minimized.  Tail shape does this and not tail finish smoothness.

The vehicle from overhead view was designed to conform to a NACA shape.  The vehicle as viewed from ahead and the sides is a "do the best as I can" shape.  The rider is part of the vehicle during the design.  It was developed using years of experience and book learning before it went into the wind tunnel.

The wind tunnel cost big money to use.  Most of us can afford to use it to validate our design and to test easily made modifications, like I did.  It would take mucho dollars to develop a shape in the tunnel.

Tufts of yarn were attached to the bike to show flow direction across the surface.  The first tunnel test was used to photograph the yarn tufts during air flow.  Also, a smoke wand was used.

"The best modification you can make is to get your head and shoulders down and behind the fairing" I was told after the smoke test.  The seat pan was lowered to do this.  It is about a millimeter above the frame tubes and it is an inch or two lower than it was before.  It was narrowed, too, to allow my knees to tuck in better along the bike sides.

Posting pictures with the narrative is problematic after the website crash.  The post following this will be an attempt to post pictures.