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Author Topic: Bloodhound latest news  (Read 8121 times)

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Offline fordboy628

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Re: Bloodhound latest news
« Reply #60 on: July 14, 2019, 06:06:03 AM »
I have been following the progress of the absolute world land speed record for the past 50 years. I am dumbfounded by the insistence of Thrust 2, Thrust SSC, Bloodhound, and Aussie Invader 5R to eschew pneumatic tires and instead run their vehicles on solid metal wheels.
Since the coefficient of friction of the metal wheels on dry salt lakes, or other hard surfaces, is insufficient to provide steering control they must find semi-soft surfaces to run on. Since these metal wheels obtain steering control by, in effect, machining grooves in the race course surface, they literally destroy the course as they run and cannot return on the exact same path. Also, finding the optimal surface composition for the record course seems to be adding unnecessary complication to the search for the land speed record venues.
When we ran The Blue Flame in 1970 on pneumatic tires, the steering control was excellent as the coefficient of friction approached that of rubber on asphalt or concrete. The Goodyear tires and our wheels were tested at Goodyear at speeds up to 850 mi/h without failure. The only failure in testing occurred when the wheel mounting mandrel broke loose at speed and the tire and wheel spun around in the concrete test cell. The wheel, while not being used afterward, only had some gouges on the rim from impacting the cell walls and still looked nice as a display piece.
Three of the four pneumatic tires and wheels were replaced for minor reasons on the salt flats. When one of the two front tires leaked air (probably the O-ring seal between the wheel center and the outer flange), we replaced both at the same time. One of the rear tires was replaced after a towed braking incident (locked up tire and skidded) wore through most of the thin rubber tread. The fourth tire was used for all 24 timed runs.
Since we could design and build 850 mi/h pneumatic tires 50 years ago, it should be a simple task to design and build 1,000 mi/h tires (and wheels) with the materials and design improvements since that period of time. When I think of all the time wasted by the LSR teams trying to use metal wheels for providing the steering function I am amazed. Just my opinion.

My experience is with the Oregon state highway department pavement research program.  Higher tire internal air pressures do create greater tire contact patch pressures.  It is not often a linear relationship but it is close.  The "tire pressure" in metal wheels is related to the moduli of elasticity which is magnitudes higher than the contact pressure with pneumatic tires.  Solid tires do tear up the racing surface.

It is called "common sense".

But in my experience, it turns out that it is NOT very "common" at all . . . . . . .

YMMV

The ability of other engineers to logically work through difficult engineering problems, seems to me, to have "diminished" over the span of my career.   Now it seems everyone wants to be a "specialist", with no regard for the overall program, or how "their segment" fits into the overall scheme.   You can't "get to the Moon" with that sort of attitude.   And the "moon" you do get . . . .  well, use your imagination . . . . . .  :roll:

 :dhorse:
« Last Edit: July 14, 2019, 06:15:19 AM by fordboy628 »
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Offline MAYOMAN

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Re: Bloodhound latest news
« Reply #61 on: July 14, 2019, 12:37:38 PM »
This section view of The Blue Flame rear wheel and pneumatic tire assembly will give a little better idea of what we did in 1970. The outer wheel flanges were sealed with rubber O-rings. Tire pressure was 350 psi. The tire imprint on the salt surface, with aerodynamic loading at 660 mi/h, was about 2 inches wide as the tire cross section expanded outward from inertia. The impression was barely visible, maybe 1/8 inch or less deep. With computerized solid modeling and analysis available now, the wheel design could have been more aero and less massive. We had planned to re-visit wheel fairings for the planned supersonic attempts in later record attempts. Our schedule for design and construction for 1970 was very tight, so we compromised to meet the less than 2 years' time available.
The road is long - Life is short - Drive fast

Offline wobblywalrus

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Re: Bloodhound latest news
« Reply #62 on: August 02, 2019, 02:00:42 PM »
An article about the upcoming journey to Africa.https://www.bbc.com/news/science-environment-49184375