List:
I hope not everyone is through with this topic-- I've been out of the country,
so
this is my first opportunity to get in on it.
Like many others have said, "I'm no expert, but..." I went to Bonneville for
the
first time at Speed Week this year. Had been forewarned that "getting the power
to the ground" is the biggest problem for the really powerful cars-- so I tried
to
observe everything I could about the problem, since I want to build my own
machines.
One thing I noticed was that some of the fastest cars showed very little
"roostertail" until they were well past the one-mile-- but by the "big-end" they
were really kicking up the salt.
After they had shut-down the course on the last day, I walked out and studied
the
salt on the long course at about "the three", to see if I could learn any more
about those big-end roostertails. I could see distinct tracks from some of the
vehicles. I assumed that the deepest and most distinct tracks probably belonged
to (drive) tires that were under the most stress-- the cars with so much power
that they could barely keep it "hooked-up". I saw a particularly interesting
phenomenon repeat itself in several different sets of tracks:
as the track approached an expansion joint, it would suddenly disappear;
when it reappeared on the other side of the joint, the tire was
tearing-up the salt much worse!
I assume this was due to the fact that the tires accellerated during the time
they
were unloaded, and then they just spun when they re-contacted the salt. I don't
know about that "three-foot [wide, I assume] dip" thing that someone mentioned
earlier. Didn't have a long straight-edge with me. But I could see that the
expansion joints I was looking at did seem to be depressed. However, some of
the
tire track "jumps" looked longer than three feet-- maybe around SIX feet.
Some very smart and experienced LSR people have told me that they think the most
powerful vehicles are probably loosing 15% of their potential tire thrust to
"slip". If that is right-- then clearly it can be the difference between
reaching
your speed goal, or not.
What many people have said about the practical stumbling-blocks-- in adapting a
rear suspension and getting it to work-- are all points well-taken. But the
CART
cars I'm around all still use suspensions, even on the 240mph speedways. I
think
suspensions can probably be made to work at our LSR speeds, too.
My observations have convinced me that I should begin building my LSR machines
WITH suspensions; then-- if I ever get to the point where I have an engine that
is really asking a lot of the drive tires-- maybe I will have experience that
will
give me an advantage.
Russ Mack
john backus wrote:
> ----- Original Message -----
> From: john backus
> Sent: Wednesday, October 24, 2001 7:53 PM
> To: kturk; land-speed
> Subject: Re: Rear suspension
>
> Okay, okay, this may sound really stupid but I do have a theory about this.
> What if the engine, trans and rear end were mounted on one frame unit,
> attached at the front of the engine and the body was attached to another
> length of frame with springs, shocks, etc. between the two frame sections.
> Kinda like one long ladder bar, of sorts that hinges at the front of the motor
> with all suspended together with coils and shocks between. I know this is a
> lot of unsprung weight but it could be managed and even eliminate the
> driveshaft.
>
> ??????????? John Backus
>
> ----- Original Message -----
> From: Keith Turk
> Sent: Monday, October 22, 2001 7:29 PM
> To: land-speed@autox.team.net
> Subject: Rear suspension
>
> Okay along the lines of the Trans mounting system.... I wanna do the rear
> suspension issues....
>
> My thoughts are that a fancy rear suspension to make the car leave the line
> is a Moot point at Bonneville... ( may help you at Maxton or El Mirage ) but
> once the car is through the gears it's settled down and the only real
> advantage of a suspension at all is to maintain the contact patch with the
> ground....over minor bumps...
>
> Joe Timney and I have beat this up at length and I have several idea's on
> the correct course of action for me.... But I'm curious to hear others
> thoughts on what they run and WHY?....
>
> In other words... what are your theory's..
>
> Keith ( Mayf.... what you doing Hiding out... I love your questions...
> always pointed .... which may not be pleasing to all ... however they are
> always honest and well thought out )
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