31 replies to this topic

[MG Brown]

By 1969 most cars at Indy had sprouted wings. Why did it take so long I wonder? Remember most F1 cars had fully adopted wings in 1968.

 

If memory serves, there was a rule added in the late 1960's to the USAC technical specifications that the "wings" or other air control devices, must be an intregal part of the bodywork. I believe that this rule was removed in 1972.

 

An example of this was the 1971 McLaren (Peter Revson and Mark Donohue shown).

 

[bshawn]

The 10 car has the chin spoilers, I guess to help hold the front end down and add traction to steering.    Compared to what we see today (60 years later),  the front nose design looks like an airplane you are trying to get airborne.   I assume the spoilers were an attempt to overcome this flaw in design?    Is this right or am I totally  missing what's going on  with the nose design.     

Martin,

 

The "chin spoilers" on the front of the car were not so much spoilers (devices that create aerodynamic download but also have high drag) as canards. At least they should have been. A canard is a front wing that is an aerodynamic surface (makes lift but little drag) as in the Rutan planes such as VariEze (https://en.wikipedia...i/Rutan_VariEze). For the car to corner properly, it should have a balance of download on the front and the rear wheels. Too much on the front and the car oversteers (rear wheels spin out); too much on the rear and it understeers (front wheels spin out).

 

Getting download on the front wheels is easy. Canards and spoilers both work. The airflow is clean with no engine or cockpit to muddy it. It's those pesky rear wheels that are the problem. When I worked for Lotus on download (my PhD thesis at Berkeley), i only got a small region underbody suction. But it was just where it was needed: under the rear wheels.

 

      Shawn

[bshawn]

I was trying to figure out which car was used for the Bat Car. So I found all those pics to compare.

This is my guess.

The Bat car has a Monocoque chassis and the only pic I can find other than the one with wings is this one.

Same wheels, same number same Monocoque chassis. It has a different motor in this pic.

Clearly NOT the Pactra body and I am not sure if this slot body was ever made?

In this pic it has a modified tail and engine cover and has sprouted a small spoiler.

 

I do realize some of this info and pics arerehashed but now we have Shawn onboard it always good to get a fresh eye on the subject IMO.

 

Is there a body that would be a good start for the a slot version of the Indy Bat car?

 

Jerry used an unusual frame design also. He used "D-sections" to make his monocoque. I brought my pal Ron Petrich (designer of the Lola cars in the early 70's, https://irp-cdn.mult...aded/FF 2-3.pdf, p11-12) over to Jerry's shop. Ron was a Master's degree stress designer for Lockheed Burbank where we both worked in 1966-67. He was concerned that Jerry didn't have the wheel mounts attached to the monocoque well enough. Jerry's response was that he didn't care how well they were attached.  If a crash wiped off the wheels he could fix it quickly by attaching new wheel mounts. Now THAT was a really practical reason. He made the two D-sections himself (one on each side) and had fuel inside. 

[Martin]

Hey Shawn, that was Matt that asked about the fins  BTW.

 

I was hoping you would tell us what you know about the suggestion that wings like on the Bat car (BC) may of caused the ruling body to write a rule. As MG Brown suggests.  Any inside info on that?

 

Was the Bat car the first to try a wing of this design on an Indy/USAC car. A mile stone car if it was? Well worth a slot model at least IMO. I was playing around with aluminum to see if I could make a chassis that looks like the BC #96

[TSR]

Shawn,
great story on the Eisert Bat car, but it was not the first Indy car to sport a wing. This was achieved 5 years earlier by another smart fellow (while not by far as educated as you are) by the name "Smokey" Yunnick, on his front-engine Watson/Offy roadster. It worked so well that it killed 3 mph in top speed, negating the gain in cornering speed. So off it went! 
Of course a smaller device could have been the ticket, but what do you expect from such ruffians?



 

[Martin]

Had not seen that pic before PDL thanks. It does seem a bit over the top. Literally and figuratively

 

Did you know the rule MG Brown is referring to? 

I quote MG,

"If memory serves, there was a rule added in the late 1960's to the USAC technical specifications that the "wings" or other air control devices, must be an intregal part of the bodywork. I believe that this rule was removed in 1972."

[TSR]

Yes, this rule came in 1969, to conform with the FIA banning of moveable aero devices and they did the same with wings, it had to be attached to the bodywork.
And yes, that was rescinded in 1972 after McLaren got around the rule in 1971 with a smart design.