Conference waylay::askenet_v5

Somewhere else on the web is some sort of account of something like
the following, perhaps someone can find the "original" story:

	Someone decided to strap some sort of rocket engine onto a car,
	in order to see how fast they could go.  They killed themselves
	slamming into a cliff or something like that.  When the authorities
	examined the wreck, they found the brakes entirely burned up.
	Apparently the poor soul had been trying desperately to stop.

/Eric

Reading about land speed records brings up some interesting physics
questions:

o	Suppose in order to solve the problem of finding a large enough
	space to perform the experiments, we decide to use a circular track.
	How large would this track need to be so that with normal tires
	and road friction, a 700 mile-per-hour speed could be achieved
	without the car skidding sideways off the road ?

o	Back to the straight speedway now.  Given the curvature of the earth
	(which is basically downward as far as a forward-moving vehicle is
	concerned), at what speed would a car become airborne merely due
	to that curvature ?

/Eric

    .5 is an urban legend.
    
    			Steve

re .5:  They guy's name must have been Wile E. Coyote.

re .6:  I think that question is ~equivalent to asking what is the orbital
velocity at the Earth's surface.  I don't know, but given that it is a fairly
small percent of the Earth's radius difference between low Earth orbit and the
surface, I would guess it would be in the vicinity of 18,000 miles per hour.

Burns

If memory serves me correctly, the sound barrier _was_
broken on land back in the late '70s /early '80s by a 
rocket car (hydrogen peroxide, I think) sponsored by 
Budweiser. It was not, however, a record, as they were
unable to "back it up", that is, make a run in the opposite
direction at a speed within a certain percentage (1%??) of 
the first run, which is a requirement for a "record".


Steve

Eric:

> Suppose in order to solve the problem of finding a large enough
> space to perform the experiments, we decide to use a circular track.
> How large would this track need to be so that with normal tires
> and road friction, a 700 mile-per-hour speed could be achieved
> without the car skidding sideways off the road ?

  It depends on how many G's you'll accept in the "normal"
  direction.
                                   Atlant

    
    	Eric, I think that the astronomical footprint of this round track
    	would far outweigh the advantage of a decrease in overall length.
    

    
>re .6:  I think that question is ~equivalent to asking what is the orbital
>velocity at the Earth's surface.  I don't know, but given that it is a fairly
>small percent of the Earth's radius difference between low Earth orbit and the
>surface, I would guess it would be in the vicinity of 18,000 miles per hour.
    
    
    	IE, avoid jackrabbit starts and that Camry of yours should hold
    	the road pretty well.
    

>    <<< Note 1196.10 by ATLANT::SCHMIDT "See http://atlant2.zko.dec.com/" >>>
>
>Eric:
>
>> Suppose in order to solve the problem of finding a large enough
>> space to perform the experiments, we decide to use a circular track.
>> How large would this track need to be so that with normal tires
>> and road friction, a 700 mile-per-hour speed could be achieved
>> without the car skidding sideways off the road ?
>
>  It depends on how many G's you'll accept in the "normal"
>  direction.

On a flat track or road, a well-suspended sports car can turn
and hold the road with about 0.7G lateral force (am I close on this?).
If we are allowed to bank Eric's track to whatever degree is necessary,
we can probably make the track arbitrarily small, also considering
Atlant's how-heavy-can-the-driver-stand-to-be caution.

- tom]

    Sure, haven't you ever seen one of those shows at a fair where a
    motorcycle drives around a bowl shaped "stadium until its completely
    horizontal?  
    
    Of course, I guess at that point it blurs the definition of "land"
    speed record.
    
    jeb
    

No, I don't want to bank the track at all.  Since I said "normal tire
friction", that defined the g's (a definition I assumed would be well within
human comfort zones, in other words a turning car would skid off the road
way before the human would feel adverse g affect).

Once someone verifies Tom's guess at 0.7 g, we can probably calculate our
track size fairly well.

/Eric

    
    	The Corvette supposedly is capable of close to [if not] 1G.
    

.7G is rather low for cars nowadays.  Even modestly-priced cars with good
suspensions can make over .8G.  More exotic cars can indeed push 1G.

				Steve

Back on the subject of land speed records...

> A car called the Blue Flame, powered by a propane rocket, owns the
> record now, but it's still not close to the sound barrier.

	When did Blue Flame take the record back from Thrust 2?

The latest two records from:

	http://ms.shellus.com/SpiritofAmerica/soa_lsr_holders.html

DATE	DRIVER	COUNTRY		CAR	TYPE	LOCATION	SPEED(mph)
October 4, 1983 	
	Richard Noble 
		Great Britain 
				Thrust 2	
					Jet	 Black Rock Desert
								633.470 
October 23, 1970 
	Gary Gabelich
		USA
				Blue Flame
					Rocket
						Bonneville Salt Flats
								622.407 

See the very end of .3