Author Topic: Spins on the flats  (Read 40277 times)

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Offline kustombrad

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Re: Spins on the flats
« Reply #60 on: December 24, 2014, 12:54:16 PM »
And looking at the picture of George's car on it's side again shows what I'm talking about. Which tire is destroyed from all the pressure and spinning on the salt?

Offline tortoise

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Re: Spins on the flats
« Reply #61 on: December 24, 2014, 01:31:58 PM »
Fix the "actual" issues . . .

The Speed Demon cockpit canopy extends much further forward than needed. Low drag, no doubt, but moves the CP forward a bunch.

Offline kustombrad

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Re: Spins on the flats
« Reply #62 on: December 24, 2014, 02:08:52 PM »
Tortoise, the canopy, windshield, CP, CG, etc. is not the point here and had nothing to do with it spinning. None of those caused the car to go right every time he rolled hard into the throttle and the picture of the car on its side and the left tire showing cords validates what I've said. Piles of horsepower, the car's twisting motion, loose salt and George "getting with it" were the causes of that deal. That car by design still had LOTS of records left in it!
My comment of "actual issues" was not referring to Speed Demon. George is one of my heroes in the hot rod "world" and I'm sure he'll be back to kick more butt!

Offline tortoise

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Re: Spins on the flats
« Reply #63 on: December 24, 2014, 02:46:58 PM »
Tortoise, the canopy, windshield, CP, CG, etc. is not the point here and had nothing to do with it spinning.
Quote from: Sumner
As George said in the interview in BRN (more or less) the car was stable for many runs before conditions finally were too much and it went around.  He notes that the cars CG was behind the CP and also notes that it won't be if there is a new car
Neither you nor I know whether aero forces could have stopped the spin. 
Quote
George is one of my heroes in the hot rod "world" and I'm sure he'll be back to kick more butt!
Agreed!
« Last Edit: December 24, 2014, 04:18:46 PM by tortoise »

Offline jl222

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Re: Spins on the flats
« Reply #64 on: December 24, 2014, 05:21:32 PM »
Yep, it spun left!   :-D

  That's left? rear end swings to right and is to drivers right. Guess its like making a left turn.

  Anyhow that's how the 222 Camaro spins, rear end slides to right. But its left?

  Now its almost Turkey time :-D

                 JL222 :cheers:

Offline 8

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Re: Spins on the flats
« Reply #65 on: December 24, 2014, 06:53:36 PM »
   


      And to end all this, refer to Newtons third law of physics " For every action there is an equal and opposite reaction"
. Meaning that the pinion has EXACTLY the opposite torque in relation to the ground that the engine has. Watch a nitro F/C leave the starting line, Both front wheels in the air and going straight. SAME amount of traction on each tire,maybe some chassis flex but same weight.

Offline tortoise

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Re: Spins on the flats
« Reply #66 on: December 24, 2014, 07:30:58 PM »
If the chassis is torsionally stiff behind the engine, no rear suspension or rear suspension with very strong anti-roll, engine torque won't cause much unequal wheel loading, especially with the front wheels inline or in the air. Rapid engine acceleration, like when traction is suddenly lost, will twist the whole car. You can see the result of this force when winging the engine while out of gear.
« Last Edit: December 24, 2014, 07:33:48 PM by tortoise »

Offline Ken Yooper

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Re: Spins on the flats
« Reply #67 on: December 24, 2014, 10:12:39 PM »
If the chassis is torsionally stiff behind the engine, no rear suspension or rear suspension with very strong anti-roll, engine torque won't cause much unequal wheel loading, especially with the front wheels inline or in the air. Rapid engine acceleration, like when traction is suddenly lost, will twist the whole car. You can see the result of this force when winging the engine while out of gear.


 :cheers:    Yup!
If it's worth doing, it's worth doing right.  If it's not worth doing right then it's probably not worth doing at all.  (Andy Granatelli in Gasoline Alley 1964)

Offline grumm441

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Re: Spins on the flats
« Reply #68 on: December 25, 2014, 06:46:38 PM »
So if you put the engine and transmission in facing east west ?
G
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Offline tortoise

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Re: Spins on the flats
« Reply #69 on: December 25, 2014, 07:52:44 PM »
So if you put the engine and transmission in facing east west ?
G
You'll probably increase frontal area and require some expensive custom unproven driveline bits, unless it's motorcycle powered.

Offline Stainless1

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Re: Spins on the flats
« Reply #70 on: December 26, 2014, 09:46:43 PM »
Tort... Bonneville runs on unproven bits of all types... innovation is encouraged...  :cheers:
Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Offline grumm441

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Re: Spins on the flats
« Reply #71 on: December 27, 2014, 04:12:23 AM »
Tort... Bonneville runs on unproven bits of all types... innovation is encouraged...  :cheers:

Innovation within the rules that is

G
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Spirit of Sunshine Bellytank Lakester
https://www.dlra.org.au/rulebook.htm

Offline John Burk

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Re: Spins on the flats
« Reply #72 on: January 04, 2015, 05:27:04 PM »
Hold a spinning die grinder with a cut off wheel as if it's the rear in a land speed car . If the "rear" yaws in either direction the outside "tire" dips . This says at the start of a spin the outside rear tire suddenly gets more traction guaranteeing a spin . Could spins be that simple ? Could spins start with unequal traction , gyro loading makes it worse till CP/CG takes over .

Offline kustombrad

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Re: Spins on the flats
« Reply #73 on: January 04, 2015, 06:06:33 PM »
Make sure it's an angle grinder to use that theory. Does it twist either way equally when you flip the switch (leave it on and just plug/unplug it) or just twist one direction?  When you turn it on, that's the ring and pinion torque load (twist) I was referring to with it unloading one and loading the other side. If you really want to make it like a landspeed deal, hook it to a rheostat and "hit" it. Level it off at part throttle and "hit" it hard again. Is it twisting when you "hit" it or just staying even?

Offline John Burk

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Re: Spins on the flats
« Reply #74 on: January 04, 2015, 06:59:55 PM »
Brad you may be missing what I'm talking about . It's not the acceleration of the car or die grinder , it's when the car yaws that gyroscopic force tries to roll the car in the direction of the yaw . A cut off wheel in the die grinder adds a lot to the gyroscopic effect making it more obvious . Point the axis of the spinning die grinder north . As you change the aim to NW or NE it tries to pitch up or down . Same for an angle grinder but with the 2 axis the effect is less clear .