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#1 Dunc

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Posted 29 July 2020 - 18:10

I've been reading about the 1982 season and the decision that year to ban skirts for 1983 following all of the horrific crashes of that season.  It's prompted me to look into skirts a lI have to admit, it's not a subject I knew a lot about.

 

Just out of curiosity, what would be the consequences of bringing them back? I know they made the sport incredibly dangerous but given the advances in safety etc since then, would it be possible for them to come back and not result in death?



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#2 FNG

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Posted 29 July 2020 - 18:16

No more dangerous than DRS today. It was a moveable device that if failed could and did have consequences. Much like DRS today.

 

I think the engineering standards of today would make it for the most part a non issue. We could easily have skirts today.

 

By the way you posted this in the wrong forum...



#3 Dunc

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Posted 29 July 2020 - 18:22

No more dangerous than DRS today. It was a moveable device that if failed could and did have consequences. Much like DRS today.

 

I think the engineering standards of today would make it for the most part a non issue. We could easily have skirts today.

 

By the way you posted this in the wrong forum...

 Oh dear, sorry all, the consequences of being distracted by a Zoom call!

 

Can one of the mods either delete or move?



#4 Slartibartfast

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Posted 29 July 2020 - 18:24

By the way you posted this in the wrong forum...

 

Are you sure?   ;)



#5 Dunc

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Posted 29 July 2020 - 18:24

Now it's in the right place, thanks.



#6 Izzyeviel

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Posted 29 July 2020 - 22:02

No more dangerous than DRS today. It was a moveable device that if failed could and did have consequences. Much like DRS today.

 

I think the engineering standards of today would make it for the most part a non issue. We could easily have skirts today.

 

By the way you posted this in the wrong forum...

Not quite, A DRS failure is something you're likely to notice and do something about, with skirts, the moment you'd realize you're in trouble is when the marshals are rescuing you from the tree you crashed into.

 

Also if i've remembered correctly, modern ground effect can be achieved without skirts so they won't be coming back.



#7 Dunc

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Posted 30 July 2020 - 08:32

Not quite, A DRS failure is something you're likely to notice and do something about, with skirts, the moment you'd realize you're in trouble is when the marshals are rescuing you from the tree you crashed into.

 

Also if i've remembered correctly, modern ground effect can be achieved without skirts so they won't be coming back.

 

Oh, I know they have no chance of coming back, I'm just interested in the theory of whether they could come back. Given we have better track safety, stronger cars, better medical facilities run-off areas now would that make them less of a risk?



#8 jcbc3

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Posted 30 July 2020 - 09:00

..., modern ground effect can be achieved without skirts so they won't be coming back.

 

I like old fashioned ground effect better!

 

I'm pretty certain that given a free hand and with the option of skirting the cars, the designers would go for skirts.



#9 Charlieman

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Posted 30 July 2020 - 10:11

I'll start with a brief history of skirts. Some of the details are fuzzy because teams were intentionally unclear about how they used skirts. Other errors are caused by my memory.

 

Fixed skirts were probably first used on the Chaparral and McLaren Group 7 sports cars. They were used longitudinally and laterally to create a low pressure area around/behind the driver's bottom, Chaparral using a fan. In F1 fixed skirts appeared with McLaren and Brabham in the mid 1970s, in the fashion of the McLaren Can Am cars and would have been in use at the time that Lotus were developing their wing and ground effects cars.

 

Lotus tested and abandoned a brush system (similar to a draught excluder or the seals on revolving doors) on the model 77 and 78. For the 78, Lotus also tested a fixed skirt with a hinge half way up. By the time that the Lotus 79 briefly dominated, Lotus had decided to adopt sliding skirts, arguing that they were fixed to the sidepod wall and thus were not a moveable aerodynamic entity... For the Lotus 80, the team used a sliding skirt which weaved around the rear wheel (i.e. not straight) which did not rise and fall correctly. Other teams (e.g. Ligier) experimented with straight sliding skirts in the rear wheel region (eventually banned). Sliding skirts were banned completely after a few years and minimum ride height regulations were introduced, leading to the use of fixed skirts with ride height adjusting suspension (Brabham followed by everyone else). A few more years later, the regs required 'flat bottomed' cars, leading to the diffuser, exhaust extraction and more. 

 

Skirt problems? 

* Brush skirts: Didn't seal sufficiently for late 1970s designs.

* All skirts: Low pressure could 'suck' the skirt underneath the sidepod. Lots of photos show skirts which are not hanging vertically. Trailing/running edge wear. Wear surfaces used ceramic or metal inserts which broke away creating track debris. Intermittent leaks in the venturi tunnels (caused by track bumps etc) lead to 'porpoising' -- ride height changes or pitching. Insufficient rigidity in the sidepod would have made everything unpredictable.

* Fixed skirts, with or without a hinge: Don't seal until the car is pushed down on its springs and tend to leak on anything but the smoothest track.

* Sliding skirts: Need to be straight and the rise/fall sliders require a lot of testing/development. Top teams ran a separate group to maintain skirts at the races, which increased costs. Riding over kerbs is a risky act and an extensive off-track excursion rips skirts off completely. In F1, skirt loss on one side of the car tended to result in a high speed spin -- although I am sure that there were even scarier accidents as well.

* Fixed skirts plus lowering suspension: Reduced one cost (skirt maintenance group) and introduced a new one (ride height hydraulics group). F1 teams and their suppliers had done an incredible job to create fixed skirts which worked as well as sliding skirts.

 

If sliding skirts were permitted in F1 today, thousands of spectators would die from boredom. The cars would have so much downforce that they would not budge from their line on anything but the slowest corner.

 

How much downforce did cars generate at any particular time? It's impossible to say owing to different testing facilities, but we can assess high speed corner performance (top speed through a known radius). In CART racing where venturi tunnels were permitted for a few years longer than F1, skirtless cars cornered at whopping Gs.



#10 guiporsche

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Posted 30 July 2020 - 13:43

Just one detail: if I remember well, skirts in the 74-5 Brabham's (which would explain the skirts's v-shape) and the 76-77 Mclaren's were meant to take air away from underneath the car.

Here's Coppuck on the M26:

 

“The principle of the car was to keep the air flow from underneath the car to create negative pressure on the underside of the bodywork,” designer Gordon Coppuck recalled. “I thought at the time – but I now know, of course, that I was wrong – that with all that number of square inches under the car, if you could generate a very small amount of negative pressure by keeping the air from flowing underneath, you would have more downforce. 
 
“You couldn’t really see our work. It was the plastic skirts to stop the air going under the car. We did much development with suspension, because the car understeered, so we did a new front suspension and several variations, all the things that we had done with all our previous cars.”
 
"“We had three pole positions in the last seven races [of 1977] and led five of the last six,” said Coppuck. “But it encouraged us in the wrong direction. When it came to proper ground-effect, you encourage flow underneath the car. We were working on the opposite direction trying to stop flow. That was the story of the M26, really." 
 


#11 PayasYouRace

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Posted 30 July 2020 - 15:03

I like old fashioned ground effect better!

 

I'm pretty certain that given a free hand and with the option of skirting the cars, the designers would go for skirts.

 

They would indeed, because if there's one thing that provides the best seal against the ground, it's a solid object. Even if you'e getting good stuff from vortices and the like, a skirt will do the best job.

 

 

Not quite, A DRS failure is something you're likely to notice and do something about, with skirts, the moment you'd realize you're in trouble is when the marshals are rescuing you from the tree you crashed into.

 

Also if i've remembered correctly, modern ground effect can be achieved without skirts so they won't be coming back.

 

FNG is right. Nowadays it wouldn't be a significant danger. Also, why would you be hitting trees? Are you going rallying? The main danger from the skirts was that they'd get stuck in the up position, but it's not a stretch to be able to design them to be failsafe.

 

 

 

Skirt problems? 

* Brush skirts: Didn't seal sufficiently for late 1970s designs.

* All skirts: Low pressure could 'suck' the skirt underneath the sidepod. Lots of photos show skirts which are not hanging vertically. Trailing/running edge wear. Wear surfaces used ceramic or metal inserts which broke away creating track debris. Intermittent leaks in the venturi tunnels (caused by track bumps etc) lead to 'porpoising' -- ride height changes or pitching. Insufficient rigidity in the sidepod would have made everything unpredictable.

* Fixed skirts, with or without a hinge: Don't seal until the car is pushed down on its springs and tend to leak on anything but the smoothest track.

* Sliding skirts: Need to be straight and the rise/fall sliders require a lot of testing/development. Top teams ran a separate group to maintain skirts at the races, which increased costs. Riding over kerbs is a risky act and an extensive off-track excursion rips skirts off completely. In F1, skirt loss on one side of the car tended to result in a high speed spin -- although I am sure that there were even scarier accidents as well.

* Fixed skirts plus lowering suspension: Reduced one cost (skirt maintenance group) and introduced a new one (ride height hydraulics group). F1 teams and their suppliers had done an incredible job to create fixed skirts which worked as well as sliding skirts.

 

Sliding skirts obviously. It isn't 1982 any more. The don't need to be straight (why would they?) and F1 circuits don't have the huge kerbs that they did back then. It would be the obvious way to do it, and they could be much more reliably forced onto the track to create a seal.

 

 

If sliding skirts were permitted in F1 today, thousands of spectators would die from boredom. The cars would have so much downforce that they would not budge from their line on anything but the slowest corner.

 

How much downforce did cars generate at any particular time? It's impossible to say owing to different testing facilities, but we can assess high speed corner performance (top speed through a known radius). In CART racing where venturi tunnels were permitted for a few years longer than F1, skirtless cars cornered at whopping Gs.

 

So what? If you were to have racing with full skirted ground effect, you'd be keeping things in check in other ways.



#12 PayasYouRace

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Posted 30 July 2020 - 15:06

 

Just one detail: if I remember well, skirts in the 74-5 Brabham's (which would explain the skirts's v-shape) and the 76-77 Mclaren's were meant to take air away from underneath the car.

Here's Coppuck on the M26:

 

“The principle of the car was to keep the air flow from underneath the car to create negative pressure on the underside of the bodywork,” designer Gordon Coppuck recalled. “I thought at the time – but I now know, of course, that I was wrong – that with all that number of square inches under the car, if you could generate a very small amount of negative pressure by keeping the air from flowing underneath, you would have more downforce. 
 
“You couldn’t really see our work. It was the plastic skirts to stop the air going under the car. We did much development with suspension, because the car understeered, so we did a new front suspension and several variations, all the things that we had done with all our previous cars.”
 
"“We had three pole positions in the last seven races [of 1977] and led five of the last six,” said Coppuck. “But it encouraged us in the wrong direction. When it came to proper ground-effect, you encourage flow underneath the car. We were working on the opposite direction trying to stop flow. That was the story of the M26, really." 
 

 

 

That's really outdated. As I explained in the BLAT thread, you want to encourage air to go under the car as fast as possible, lowering the static pressure.



#13 Charlieman

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Posted 30 July 2020 - 15:38

That's really outdated. As I explained in the BLAT thread, you want to encourage air to go under the car as fast as possible, lowering the static pressure.

It is imperative to know stuff without comprehension.



#14 guiporsche

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Posted 30 July 2020 - 16:03

Of course it's outdated - if you are looking at it with the benefit of 40 years of technical hindsight.

The point I made was historical. Skirts (defined broadly) first appeared in F1 not because race-car designers, with the knowledge they had at the time, intended to use them to generate ground-effects (which most had no clue about) but rather with the opposite goal (as in not encouraging air to go under the car as fast as possible).

From which you can take the conclusion that it is not because a F1 had skirts that it can be seen as anticipating ground effects. 



#15 desmo

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Posted 30 July 2020 - 17:47

If you really want to know the genesis of aero skirts in F1, you will pretty much have to get a copy of Wright's "F1 Technology" book and read "Appendix A—Ground Effect" where he describes his work on the development of skirts for the Lotus T78, the first F1 car to successfully use ground effect with skirts. Gordon Murray had used a transverse skirt on the BT44 in 1974, but it wasn't really informed by ground effect aero. 



#16 Pingguest

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Posted 01 August 2020 - 11:45

Peter Wright quite recently proposed reintroducing skirts to overcome Formula One's overtaking problem.

http://www.youtube.c...h?v=1mNmY5JYmiE