land speed / salt lakers - suspension?

[Jantrix]

I've got something ...........different in my head concerning a land speed car. The idea is unlike anything I've seen before and like as not would be completely ill suited as a land speed car, but man I think it will look wicked.

Something like this.

Yep, twin rear engines and the rear tires out in back of the car. I'm trying to figure out the physics of this odd ball and was wondering if adding a rear suspension would be done on something like this. I know it's a fictional car that would never be built in reality, because the whole idea is ludicrous, but I'm gonna build it anyway. I got the idea from seeing a big offshore racing boat and thought about building the automotive equivilant.

Just looking for some feedback if anyone has a moment.

Edit, I'm planning to drive the rear wheels thusly.

Edited August 6, 2011 by Jantrix

[Harry P.]

That is so impractical already.. I don't see how adding a rear suspension would make it any more "feasible."

[diymirage]

seems to me that if i were to build something like this i would apply the same principles as they bo when building a motorcycle

just build two ladders bars that act as a swingarm and put your suspension on there

kinda like the second picture in this link only with a drive shaft and much wider, with a spring/shock absorber on each side

http://www.members.tripod.com/groep004/Swingarm.htm

[Jantrix]

Actually I'm thinking there isn't even going to be a drive shaft, or at least something very short like a dragster, so suspension would be a moot point. Thanks for the info though Eelco. And Harry you are so right, but lets face it, it's a model. It's not supposed to be practical. Just fun.

Edited August 6, 2011 by Jantrix

[Harry P.]

It's not supposed to be practical. Just fun.

I know. That's why I added the emoticon.

BTW... land speed cars have very narrow tires. Less friction = more speed. No LSR would run those humongous rollers you have in your photo.

But then again, that's being logical.

Never mind...

[diymirage]

you know, i am working on a top secret project myself where the rear end bolt right up to the engine...no driveshaft what soever

or rear suspension

im thinking of calling it the suicide machine

if you DO build a monster like this with rear suspension and no driveshaft wont the whole engine follow the movement of the rear axle ?

[Jantrix]

BTW... land speed cars have very narrow tires. Less friction = more speed. No LSR would run those humongous rollers you have in your photo.

But then again, that's being logical.Never mind...

Good point. Maybe I'll just call it an altered wheelbase dragster. You might actually find such a machine on a drag strip more than a Speed Week event.

you know, i am working on a top secret project myself where the rear end bolt right up to the engine...no driveshaft what soever

or rear suspension

im thinking of calling it the suicide machine

if you DO build a monster like this with rear suspension and no driveshaft wont the whole engine follow the movement of the rear axle ?

Well most rail type dragsters don't have a rear suspension at all. I think it would be something like that. Also I've heard that a lot of salt lake streamliners have the axles hard mounted to the chassis like a hard tail motorcycle.

Edited August 6, 2011 by Jantrix

[MikeMc]

have to have some suspension...ask John Teresi...he knows a bit about LSR Bikes...meanwhile check this one out...

http://theselvedgeya...-tragic-result/

http://www.sporttruc...ruck/index.html

I keep reading about NO suspensions in the early MT ans Summers Bros....check out Harrys 29 in ROM...

http://www.gatsbyonline.com/main.aspx?page=text&id=526&cat=auto

Edited August 6, 2011 by MIKE THE MANIAC

[Alyn]

Suspension vs no suspension is still debated in the LSR community. There are plenty of cars that have axles rigidly mounted to the chassis. Typically, if a car is built in a stock or modified category and already has a suspension, it will be retained. Cars without suspension are more likely to be in the special construction clases which includes the streamliners and lakesters and run at the higher speeds; 200+.

As Harry mentioned, you would not see a tire that wide on the salt. The only exception I've ever heard of are a group of guys that run NASCAR spec cars including their original rubber. There isn't a specific class for NASCAR, so they are "time only" entries. Another thing that jumps out about your layout is the rear axle width. The tires would be tucked in within the width of the car body to minimize drag.

Finally, you car would not fall into any known class, so like the NASCAR entries mentioned above, would only be allowed to run for time slips.

What-ifs are always fun, though it might be a better project for the drag strip.

[Agent G]

If you've never been on a dry lake bed, or the salt flats of Utah you will be surprised the first time.

Actual dry lake beds aren't flat per se. You can get away with rigid suspension, to a degree.

The salt flats are flat yet still posess a texture, if you will, to the surface.

Vibration is a factor. Will a run generate vibes to a degree control will be lost, or will the suspension allow the car to take flight, despite ground effects, due to the vibration?

Just rambling.

G

[Harry P.]

If you've never been on a dry lake bed, or the salt flats of Utah you will be surprised the first time.

Actual dry lake beds aren't flat per se. You can get away with rigid suspension, to a degree.

The salt flats are flat yet still posess a texture, if you will, to the surface.

Vibration is a factor. Will a run generate vibes to a degree control will be lost, or will the suspension allow the car to take flight, despite ground effects, due to the vibration?

Just rambling.

G

The world record holders don't have a suspension system, do they? I'm talking about the rocket cars, the fastest of the fast.

[Agent G]

At that speed, ground effects generate enough down force to render any suspension useless. Those puppies wear tires that put a rockcrawler to shame. The tires themselves are the "suspension".

G

Edited August 7, 2011 by AgentG

[Alyn]

At that speed, ground effects generate enough down force to render any suspension useless. Those puppies wear tires that put a rockcrawler to shame. The tires themselves are the "suspension".

G

Just the opposite, actually. Suspension movement renders ground effects unpredictable.

Ground effects see limited use on cars running in the 300 to 400+ range. Land speed racing is one of the few if not the only motorsport where weight is a good thing.Weight is used to maximize traction rather than down force. Aero effects create drag. Drag is the greater evil when maximum speed is the goal. I've heard accounts of drivers saying the once you get above 300, things seem to smooth out.

Aero once again becomes critical at the ultra high speeds of the jet and rocket cars. Once you enter the arena of Andy Green, aero is about the only realistic way to control the car which is literally flying on the ground.

[Dr. Cranky]

I agree with Chuck, sleek = more speed = more salt in the eyes!

[Jantrix]

I'll likely re-dub this beastly what-if a drag racer then, because the huge tires out back are something I just can't live without. However this is a seriously back burner build that I'm just kicking around. Thanks very much to everyone who chimed in. Great info.