<VV> Oversteer?

[Ken Pepke]

On Jan 23, 2013, at 8:56 PM, ricebugg at comcast.net wrote:

> All:  In the movie I referred to earlier that Chevy R&D did for the lawyers, one of the situations was this.  They put a Valiant, Falcon and a Corvair on a skid pad...but not at the same time.  The skip pad had a series of concentric circles on it.  Driver of each car turned wheel and established study state speed around the inner circle, going clockwise.  Then he locked the steering wheel by bracing left arm on arm rest.  Then gradually increased speed.  The two other cars kept going further and further out on the skid pad until they went off screen.  The Corvair went out about 1.5 lanes, and snapped 90 degrees to the right and stopped basically perpendicular to line of travel.  
> 
> I call what the Falcon and Valiant did understeer, and what the Corvair did oversteer.  

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The movie to which you refer may be titled 'Car on Trial.'  It was shown at the 1979 CORSA Nationals.   In 1980, I convinced Paul Winchell [?]  [I have always had a poor memory for names and getting close to 70 has not helped me a bit] who was the VP in charge of the trials, to release it to the DACC for our Homecoming and to CORSA.  It was produced back in the white shirt and tie days and they felt they did not project a desirable image.

Normally the lateral acceleration 'G' test is done on a 200' radius.  Holding the steering wheel in a position to keep the vehicle at that radius.  The vehicle is accelerated gradually causing the 'G' meter to register higher and higher.  An understeering vehicle will require higher and higher steering input effort as the vehicle speed increases.  An oversteering vehicle will require less and less steering effort and the steering wheel input will have to be turned to straight ahead as the vehicle moves through the neutral steering point and then to the RIGHT as the vehicle crosses over into an oversteering condition.  This is NOT a condition for the faint of heart!  In either case, the 'G' rating is established right at the maximum edge of traction … no matter where the vehicle goes beyond that point.

In the 'Car on Trial' movie the test vehicle is circling the skid pad to the left continually holding the radius at .72 'Gs' and the throttle is wide open.  With the 102hp engine there was not enough power to go faster.  It is clear in the Film that the steering wheel is held to the LEFT and the test drivers are laughing and noting the 'G' meter.  The vehicle is CLEARLY understeering!  Could it be driven to an oversteering condition by installing a much more powerful V8 engine?  Perhaps … but this discussion is about 'stock' Corvairs.

These results were repeated in a court ordered test session, by an independent testing lab, at Ford Motor Company at the Dearborn test track with quite similar results.  
Ken P
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> 
> Don't know what anybody else calls it.  Maybe we are using the same word to mean two different thing.   Racers induce oversteer by not lifting the throttle on turn in, and then balance it with steering and throttle.  Most of the rest of us are not that good, and while we can sometimes get it right on occassion, racers do it corner after corner, lap after lap.  They are different than us.   
> 
> Any a car can be provoked to do all kinds of stuff.  At the limit, should you choose to go there, the Corvair will go off the road backwards at about the same spots the other two go off frontwards.  How deep the dodo is depends on the road you choose to do dumb stuff on.  

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Yeah, all kinds of stuff … In the 'Car on Trial' film they do the 'spin the steering wheel 180 and then let it go' trick :-)  The Falcon went absolutely wild turning itself right and left until it spun itself out!  The Corvair, on the other hand, just made the turn. 
Ken P
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> 
> Oh, and I have since remembered spinning a Corvair in a autocross.  Seth was there.  
> 
> Historically Yours,
> 						James
> 
> PS: And scared looks for a place to change your pants.
> 
> Message: 7
> Date: Wed, 23 Jan 2013 11:07:00 -0500
> From: Ken Pepke
> Subject: Re: Autoweek ~ "ill-handling Corvair" - Really ?
> To: Vair Views 
> 
> OK, first example :-)  
> 
> Answer to the question ? everyone!  Because a Corvair does not oversteer.  What it DOES do is understeer LESS than most other stock cars.  Can they be spun out?  Yes, but it requires some pretty sloppy driving.  But, so can a Falcon be spun out and in the tests back in the day, it produced the lowest rate of lateral acceleration of all cars tested. 
> 
> To quote ole 'DocHudson' [the movie, Cars] "You have to turn right to go left."  Of course, the racers induce oversteer with the throttle.  No stock Corvair ever had the torque to do that.  Honestly now, in the hardest left hand turn you have ever made with a Corvair, which way were you turning the steering wheel [before you lost it]?  An 'oversteering' vehicle is started into a left turn by turning the steering wheel to the left to get the turn started, then the wheel will have to be turned to the RIGHT to maintain the left hand turn.  The faster one goes the harder to the right the wheel must be turned.
> 
> Ken P
> Wyandotte, MI
> 65 Monza 110hp 4 speed 2 door
> Worry looks around; Sorry looks back, Faith looks up.