31 replies to this topic

[Herbert]

While doing some research on the Cunningham C6-R I noticed that the car race in different configurations.

Apparently even at Le Mans 1955 the car was driven with different bodyworks. But this is not mentioned in neither articles or book I have about the cars and the race.

Version 1




Version 2 (with openings in front of the rear wheels)



All images found in the www.

When (and why) did they race which version during the weekend?

[Doug Nye]

Here's C6R in its final and current form, with Jaguar D-Type engine and D-Type-derived front clamshell body section. It's photographed at the Collier Collection in Naples, FL, three weeks ago, during their 7th Connoisseurship Symposium. Dario Franchitti drove the car briefly, along with the preceding model Cunninghams lined-up beyond, and his immediate reaction to the C6R was that it immediately felt like a well-sorted race car, not a competition version of some production design. The car is due to feature in this year's Goodwood Festival of Speed, together with the Collection's much-loved ex-Briggs Cunningham Collection straight-8 Delage 1.5LS - which is the most original survivor of that landmark GP design. Miles Collier has been one of the Festival's most ardent and longest-faithful supporters, having - I believe - provided entries at almost every event - Museum Director Scott George bringing them over each year.



Not C6R but C4R taken by intrepid passenger while I rumbled around Naples byways in the great thunderous beast. From cold, as I joined the public road at a tee-junction, do you know it has NO brakes whatsoever. The drums warm quite rapidly with use, however, and once they have 'come in' they are remarkably powerful. It's one whole load of motor car, whichever way you slice it. Note the Indy-like steering wheel rake... Different strokes for different folks.

Photos Strictly Copyright: The GP Library

DCN

Edited by Doug Nye, 06 April 2013 - 23:18.

[RA Historian]

Lime Rock Park's big Labor Day Historic meet this year will have a definite Cunningham flavor. As I understand it, a number of Cunningham drivers, etc., will be on hand; although sadly their numbers have dwindled to just a few. The Collier Museum is said to be bringing a number of Cunninghams to the meet. To top it off, Dalton Watson Books will be rolling out its massive 600+ page new book on the history of Cunningham.
Tom

[Repco22]

While doing some research on the Cunningham C6-R I noticed that the car race in different configurations.

Apparently even at Le Mans 1955 the car was driven with different bodyworks. But this is not mentioned in neither articles or book I have about the cars and the race.

Version 1




Version 2 (with openings in front of the rear wheels)



All images found in the www.

When (and why) did they race which version during the weekend?

Your first pic shows a small opening in front of the rear wheels and the second appears to show some undulations above that hole.
I wonder if there are temporary covers over the large holes and they were later removed.

[Doug Nye]

Your first pic shows a small opening in front of the rear wheels and the second appears to show some undulations above that hole.
I wonder if there are temporary covers over the large holes and they were later removed.

I suspect that Repco is spot-on and at the time the 'closed' photos were taken the intakes were actually still taped and wax-paper covered in freight mode, as delivered to the circuit.

DCN

[simonlewisbooks]

All images found in the www.

That one is copyright Simon Lewis Transport Books.
Set of three prints are available from my website (corresponding side and tail views of the same car)
Visible on this page
http://shop.simonlew...-set-1083-p.asp

[D-Type]

Another question. The car had a 3-litre Offenhauser engine. The well-developed Indianapolis 'Offy' engine was 4.5-litres. Why did they produce a new smaller engine for Cunningham rather than modify the Indy engine to run on petrol? Or was the 3-litre engine based on the engine used in midgets?

[Odseybod]

I suspect that Repco is spot-on and at the time the 'closed' photos were taken the intakes were actually still taped and wax-paper covered in freight mode, as delivered to the circuit.

DCN

Not exactly disagreeing but this pic from our archive suggests that it did at least some running with the intakes covered - maybe to avoid the CBT (Cold Brake Trauma) Doug experienced in the C4R?



(Photo copyright Classic Cars Archive)

[arttidesco]

My own theory that the blanked off inlets might be part of a low drag 'qualifying set up' are dispelled by this linked photo that appears to show the start of the 1955 race.

[rudi]

My own theory that the blanked off inlets might be part of a low drag 'qualifying set up' are dispelled by this linked photo that appears to show the start of the 1955 race.

Right, the car had always the intakes covered during the race.

[Repco22]

Right, the car had always the intakes covered during the race.

The post #1 pic, allegedly of Sherwood Johnston on Saturday afternoon, shows intakes AND headlights uncovered while the post #8 pic shows BOTH covered.

[rudi]

The post #1 pic, allegedly of Sherwood Johnston on Saturday afternoon, shows intakes AND headlights uncovered while the post #8 pic shows BOTH covered.

Wrong caption, it's taken during practice.
Headlights were covered until night...

[D-Type]

Does anyone know the times of the practice sessions as they might provide a clue? ie
When were the night time and daytime practice sessions?
Was there a session that covered both?

[Repco22]

Another question. The car had a 3-litre Offenhauser engine. The well-developed Indianapolis 'Offy' engine was 4.5-litres. Why did they produce a new smaller engine for Cunningham rather than modify the Indy engine to run on petrol? Or was the 3-litre engine based on the engine used in midgets?

Duncan, an Offy enthusiast friend says that the Cunningham motor would have been a destroked Sprint motor. Sprint motors are
smaller than Championship, Indy motors at 220ci against 270ci. Apparently the biggest a midget motor can go is 120ci and at that it is fragile.

[D-Type]

Duncan, an Offy enthusiast friend says that the Cunningham motor would have been a destroked Sprint motor. Sprint motors are
smaller than Championship, Indy motors at 220ci against 270ci. Apparently the biggest a midget motor can go is 120ci and at that it is fragile.

That's what I was getting at - why reduce the capacity? As a generalisation, 'stretching' an engine works but reducing the capacity doesn't as everything that is sized for the more powerful engine will be oversize and overweight when reduced. Surely they would have done better to stick with the 3.65 litre of the '220'?

But we still haven't resolved the original question about the [rear brake or rear axle] cooling openings.

[Repco22]

That's what I was getting at - why reduce the capacity? As a generalisation, 'stretching' an engine works but reducing the capacity doesn't as everything that is sized for the more powerful engine will be oversize and overweight when reduced. Surely they would have done better to stick with the 3.65 litre of the '220'?

But we still haven't resolved the original question about the [rear brake or rear axle] cooling openings.

A stab in the dark; Perhaps there was too much drag with the openings and they gained some top speed and found the brakes worked OK with them covered.

[D-Type]

Does anyone know the times of the practice sessions as they might provide a clue? ie
When were the night time and daytime practice sessions?
Was there a session that covered both?

To answer my own question. The relevant Motor Sport report tells us:
On the Wednesday there was a night practice session. On Thursday the practice session included two hours of daylight. On Friday there was only a short night practice from 9pm to 11pm.

So, the shot of the car on track with the openings covered was presumably taken during the Thursday practice session while the one showing it with them uncovered was taken during the race, as the caption says and the size of the crowd suggests. The photo of the car in front of the pit with the team around it could have been taken at any time but it's likely to be either Wednesday or Thursday afternoon while waiting for practice to start. And the same applies to Simon Lewis's three pictures of the car on grass alongside the caravan which I would suggest were taken on the Wednesday.

I can't see them taping up the ducts during the race so I think the logical conclusion is that they tried covering the ducts in practice but raced with them opened up. I accept that it is feasible that it started the race with them covered up and had them uncovered at a pit stop but I can't think why they would do that.

[rudi]

To answer my own question. The relevant Motor Sport report tells us:
On the Wednesday there was a night practice session. On Thursday the practice session included two hours of daylight. On Friday there was only a short night practice from 9pm to 11pm.

So, the shot of the car on track with the openings covered was presumably taken during the Thursday practice session while the one showing it with them uncovered was taken during the race, as the caption says and the size of the crowd suggests. The photo of the car in front of the pit with the team around it could have been taken at any time but it's likely to be either Wednesday or Thursday afternoon while waiting for practice to start. And the same applies to Simon Lewis's three pictures of the car on grass alongside the caravan which I would suggest were taken on the Wednesday.

I can't see them taping up the ducts during the race so I think the logical conclusion is that they tried covering the ducts in practice but raced with them opened up. I accept that it is feasible that it started the race with them covered up and had them uncovered at a pit stop but I can't think why they would do that.

The crowd ? Not as on race day.

The photo in front of the pits with all the team staff was taken on satturday.

[rudi]

The start Briggs Cunningham driving.

[simonlewisbooks]

And the same applies to Simon Lewis's three pictures of the car on grass alongside the caravan which I would suggest were taken on the Wednesday.

Those three shots show the car covered in the kind of grime that's very much post-race/retirement rather than pre-practice.

Just to add a further race-day shot, although obscured and considerably blown up from a wider angle photo, it does back up the lack of vents.

[D-Type]

I see what you mean. It must be the other way round as Rod suggested. They tried it in practice with the ventilation ducts open but decided to run in the race with them blanked off.

[BMH Comic]

I see what you mean. It must be the other way round as Rod suggested. They tried it in practice with the ventilation ducts open but decided to run in the race with them blanked off.

Im not too sure if they are Brake ducts anyway? Funny place to put them. and what plumbing is inside? None I would suggest.

Understanding a little about these early wings and there aerodynamic effect, I was curious if there is a corresponding opening in the back of the bodywork? Does it exhaust beside the wing or out through the bottom of the body at the rear??

[simonlewisbooks]

Tyre cooling maybe? Or some early form of air-pressure venting for the wheel arch area?
Given the lack of wind tunnels back then I guess it was often a case of suck-it-and-see with any aerodynamic development.
The car looks so much better with the vents blanked off!

[BMH Comic]

Tyre cooling maybe? Or some early form of air-pressure venting for the wheel arch area?
Given the lack of wind tunnels back then I guess it was often a case of suck-it-and-see with any aerodynamic development.
The car looks so much better with the vents blanked off!

I think these guys understood a lot about aerodynamics having just lived through an era of great technical development being WWII. They certainly didn't bolt on the rear wing for no good reason, Jaguar very much understood the advantage and MB built the streamlined F1 car with that very principal in mind. That was long before this car. Whilst not knowing my elbow from my earhole on this particular vehicle, I would suggest that it would not have had inner mudguards it, would have at best a floor in the rear and that would make the rear body one very efficient parachute on a long straight, thus my question as to rearward openings in the body, it would let the air out of the body that would have been blown in through the openings in the low pressure area at the vent. Most top level cars of the day had venting at the high pressure areas, they knew about it at Porsche and they had winning cars before this baby

Edited by BMH Comic, 10 April 2013 - 11:10.

[ry6]

To me this is what 'spices' up Le Mans.
Brave efforts like those of Briggs Cunningham.
Different 'one offs'
The recent Delta Wing car being an example.

[simonlewisbooks]

I think these guys understood a lot about aerodynamics having just lived through an era of great technical development being WWII. They certainly didn't bolt on the rear wing for no good reason, Jaguar very much understood the advantage and MB built the streamlined F1 car with that very principal in mind.

Even with a high-tech outfit like Mercedes it was the drivers first hand experience (rather than the engineers calculations) that discovered the airbrake on the 300SLR gave a degree of 'stability' (downforce) when partly raised, which I think Moss mentions in several of his books.
And when Porsche produced the original 917 in 1969 it suffered from horrendous instability from lift on the Mulsanne, even before it's fancy little flappy-paddle rear winglets were deemed illegal until fixed in position(at which point it was even worse). So I'm not sure how much anyone really understood aerodynamics on race cars, at least until wind tunnels with moving floors came into being.

[BMH Comic]

Even with a high-tech outfit like Mercedes it was the drivers first hand experience (rather than the engineers calculations) that discovered the airbrake on the 300SLR gave a degree of 'stability' (downforce) when partly raised, which I think Moss mentions in several of his books.
And when Porsche produced the original 917 in 1969 it suffered from horrendous instability from lift on the Mulsanne, even before it's fancy little flappy-paddle rear winglets were deemed illegal until fixed in position(at which point it was even worse). So I'm not sure how much anyone really understood aerodynamics on race cars, at least until wind tunnels with moving floors came into being.

I do agree, Bruce McLaren a good example of drivers knowing more about the aerodynamics than the draftsman! He didn’t have the advantages of a wind tunnel either.

Notwithstanding this, ask any tail gunner in a Lancaster about aerodynamics and he can tell you more than the Engineering department could! More ways to learn than building a car if you get my drift.

Back to this lovely little car the Cunningham. C6R. Now as I pointed out I wouldn’t know anything about the car but my eyes tell me that the image of the car with the vents has numbers on the wing and the other images don’t. A fair call that its a different day but I would suggest that this body rear section at least isn’t the same as shown in the other two images? Could it be that there were two different bodies for this baby or is a spare car and thus the different numbering? The frontal shot doesn’t even look similar in that area? In 1955 did teams take replacement body sections to the track? I know that the sedan cars did in the era.

[D-Type]

I think aerodynamic knowledge in the fifties was patchy and variously applied. A few examples:
The Disco Volante Alfa Romeo and D-Type Jaguar had curved sides to reduce vulnerability to side winds.
The Cunningham C5R body shape was similar to an aerofoil and generated a lot of lift. This led to its crash at Reims and is one reason it didn't reappear at Le Mans the following year.
Despite its all enveloping bodywork the Merceds W196 streamliner still had ventilation ducts in the rear wings to get cooling air to brakes, back axle and tyres.
Competition E-Type Jaguars had vents added to aid cooling of the back axle.
The lack of success of the Ferrari, Maserati, Cooper and Vanwall 'Reims special' streamliners. Admittedly this can mainly be attributed to the lack of development as it was not economic to fund it for 1 or maybe 2 races in a season.
The 300SLR air brake being hinged at the rear making its use to stabilise the car less effective than if it had been front hinged.
The evolution of the Bristol 450 despite the aerodynamic knowledge that was available from Bristol's aircraft engineers.
The tale that Moss tells of when his Cooper-JAP blew up and they found that smoke came out of the cooling air inlets.

Edited by D-Type, 21 August 2013 - 21:30.

[simonlewisbooks]

The tale that Moss tells of when his Cooper-JAP blew up and they found that smoke came out of the cooling air inlets.

I love that

[arttidesco]

Tyre cooling maybe? Or some early form of air-pressure venting for the wheel arch area?
Given the lack of wind tunnels back then I guess it was often a case of suck-it-and-see with any aerodynamic development.
The car looks so much better with the vents blanked off!

 

Thanks to some help from Cunningham Motorsport Historian Lawrence W. Berman, Paul Kierstein from the photo archive and Sondre Kvipt in Norway I have managed to solicit this response to some of the questions raised here from the C6R's designer Mr. Bud Unger.  Quotations are unedited.

 

 

"I received your E-mail concerning questions about air vents appearing and disappearing in the rear fenders of the C-6 Cunningham? I could not find the Link. and without a picture of what your friends are questioning, I don’t have a clue as to what they want o know?

All their questions about “holes were cut’ , air ducting, holes appearing an disappearing are all strange terms to me. In fact, the water cooled brake experimenting project was tried on another experimental Ferrari car ,not the C-6. So what your friends  are seeing might be an illusion in the picture? No changes in body design of the C-6 after I finished the car and it was entered in the LeMans , France race were made. The changes, to resemble jaguar styling, were made long after I had  finished building the C-6,and prior to it being placed in the Museum in Naples, Florida. Allow me to start from the beginning : When I was assigned the project of designing and building The C-6 Cunningham, the air cooled brake project was past tense, but was a factor in my design assignment by Briggs. The engineers wanted maximum air flow to the brakes front and rear! So, the entire shaping of the body styling was a factor. I made the front air intake as large as possible and also extra air intake on both sides beside the main grille air intake . Next, I tapered the side of the body in from the front fenders all the way back to the rear fenders and by large air scoops  to get maximum ram air into both rear brakes. This design is very evident and noticeable in all the photos! That is about all that I can help you with at this time."

 

 

After seeing the links to this thread Mr Unger continued ...

 

"I looked at the three links. It looks to me that all three pictures were taken of the C-6

at the same race at Le Mans 24 hour race? For some unknown reason the picture taken at the pit stop does not show the vents in the back fenders?, but the other two clearly do? A mystery? But, the C-6 , in all three links reflects exactly the way that I designed it in every detail!"

 

The blow up above appears to show the blanking off a little more clearly.

 

I have passed on our collective thanks to Mr Unger for his response.

[arttidesco]

One further thought on the blanked off C6R rear brake brake ducts, it appears that Cunningham had thought about using a 340hp Ferrari V12 motor in C6R which, had it been fitted, would surely have created more work and therefore heat from the brakes. Maybe running with the 270 hp Offy that was actually used the car brakes did not reach critical temperatures so easily.

[D-Type]

I've just found another photo of the car on page57 of Mike Lawrence's Directory of Classic Sports-Racing Cars (1987).  Unfortunately I don't have a scanner.  It shows the car on track and somewhat grimy, it has no visible rear brake ducts and the lights have no tape, ie the same as Simon Lewis's photos.  So it looks as if it raced with the ducts blanked off but practiced with the ducts open.