21 replies to this topic

[mariner]

I suppose there is nothing very new in basic physics and , sure enough, GE can cause porpoising = as Stephen South found out way back in the 1970's witht he Lotus 80.

 

Se related video at botom of this link 

 

 

https://www.autospor...lution/8512081/

 

 

[Bikr7549]

The RC forum has a topic on this, with some interesting comments and info.

Bob

Edited by Bikr7549, 26 February 2022 - 17:27.

[Henri Greuter]

To this day I still recall seeing Roberto Guerrero driving the Ensign bouncing over the front straight of Zandvoort in 1982.

Scary.

[AllanL]

Kids, eh? Those who cannot remember the past are condemned to repeat it! (George Santayana-1905)

Correct me if I'm wrong, but has not one of the mantras of each change of F1 rules for the last 20+ years been that the new rules would enable more overtaking than the previous set of rules?

Maybe one day.

The suggested solutions are to raise the car and/or soften the suspension. Both of which reduce the maximum downforce from the underbody.

This infers that those who are suffering the most may be pushing the envelope to maximise downforce. So good luck with telling the designers they need to back off these settings.

Getting a compromise that produces the most downforce across a lap should be the goal, but the temptation to go for peak downforce may blind some to the optimum balance across a lap/race.

Nothing new there, the first Honda turbo engine allegedly had a power curve like a light switch - which made Keke Rosberg's win in the Detroit GP all the more remarkable. Later iterations of the engine apparently had a more usable power curve. (Nostalgia link there - in case those on the Racing Comments Forum complain that oldies are encroaching on their greater wisdom.)

[GreenMachine]

Yeah, whodathortit?

 

I'm sure they will find a cure, but it may come at a cost in ultimate DF, given a lot of the tools have been taken away.  Allegedly the Maccas seemed to suffer less, but testing ... 

[Doug Nye]

The unfortunate Lotus 80 is the first ground-effects F1 design that I recall having been seriously beset by porpoising at speed.  Having initiated slender chassis/side-pod underwing developments with the Types 78 and 79, Colin and his team went for longer, larger area underwings in the 80 but in action lost adequate control of their effect.

 

The way it was described to me was that once almost any bump or longitudinal deflection caused the front end of the car's lengthy undersurfaces to lose lift, the effective aerodynamic centre of pressure would race rearwards, the rear suspension would suck down, reach its bump limit and react, causing the rear of each undersurface then to lose effective suction.  By that moment the front end would regain enhanced effect and the aerodynamic centre of pressure would race forward once more. Whereupon the front suspension reacted that added load and the process would repeat - the CoP being out of control, flickering back and forth.  Once this 'porpoising' set in, the car had become "self-exciting" as Colin put it - regretfully - while claiming "But it's nothing we can't fix".

 

Topside wings - which the original concept had sought to obviate - were added, but as for "It's nothing we can't fix", as the season progressed we were asking the question "Oh really?".  After the Lotus displays of '77-78 this was dispiriting for the team and its fans, but it was also so good to see Williams, Brabham - and, tee-hee, Ferrari - doing a far better job.

 

Adopting ever-stiffer, lesser-travel suspension settings to minimise pitch-change proved to be one obvious fix, but that inflicted brutal shock loads which proved destructive of both cars and their drivers' will to live with it...  

 

So here in 2022 we see something of a replay.  But top team's capabilities to "fix it" are now way beyond anything that Team Lotus possessed in 1979. This is when all those hundreds of technical team personnel can really earn their keep.  We shall see.

 

DCN

 

[Nemo1965]

The unfortunate Lotus 80 is the first ground-effects F1 design that I recall having been seriously beset by porpoising at speed.  Having initiated slender chassis/side-pod underwing developments with the Types 78 and 79, Colin and his team went for longer, larger area underwings in the 80 but in action lost adequate control of their effect.

 

The way it was described to me was that once almost any bump or longitudinal deflection caused the front end of the car's lengthy undersurfaces to lose lift, the effective aerodynamic centre of pressure would race rearwards, the rear suspension would suck down, reach its bump limit and react, causing the rear of each undersurface then to lose effective suction.  By that moment the front end would regain enhanced effect and the aerodynamic centre of pressure would race forward once more. Whereupon the front suspension reacted that added load and the process would repeat - the CoP being out of control, flickering back and forth.  Once this 'porpoising' set in, the car had become "self-exciting" as Colin put it - regretfully - while claiming "But it's nothing we can't fix".

 

Topside wings - which the original concept had sought to obviate - were added, but as for "It's nothing we can't fix", as the season progressed we were asking the question "Oh really?".  After the Lotus displays of '77-78 this was dispiriting for the team and its fans, but it was also so good to see Williams, Brabham - and, tee-hee, Ferrari - doing a far better job.

 

Adopting ever-stiffer, lesser-travel suspension settings to minimise pitch-change proved to be one obvious fix, but that inflicted brutal shock loads which proved destructive of both cars and their drivers' will to live with it...  

 

So here in 2022 we see something of a replay.  But top team's capabilities to "fix it" are now way beyond anything that Team Lotus possessed in 1979. This is when all those hundreds of technical team personnel can really earn their keep.  We shall see.

 

DCN

 

Funny. I remember it slightly different: that all ground-effect cars would suffer from porpoising, it was a matter of course and there were two ways to battle this: rise the ride-height (no, no, no, no), stiffen the suspension immensely or find some clever way to make the car less respondent to the undulations in the road. THAT was one of the clever ideas of the Lotus 88 after all, to haven an outer chassis with the so important sealing skirts that would be totally flexible and following the road while the inner chassis with the driver would be rock-solid... (BTW: I always found the rumour hilarious that Chapman all winter was trying and lobbying to get the diameter allowed for the underbody of the F1-cars diminished... yes diminished. To that dimension? Much more narrow than the the best cars of 1980 (The Williams, Ligier, Brabhams), more like that of the yet to be revealed slender Lotus 88...

 

Remember the famous line from Alan Jones who tested a totally-spring less Williams in 1980 and rather condemned the harsh drive. 'Why don't you sit on your wallet,' said Frank Williams. 'Why don't you give me something to put in it?' Alan retorted... Not only funny, but this story also underlined that porpoising and the need for an idiotic harsh suspension were relevant for more than the Lotus 88, the Arrows A2 and the Ligier JS 19... 

[mariner]

As an avid fan of Peter Wright, Colin Chapman and Lotus I will just say the same thing again  - the Lotus 88 had the capacity to solve all these problems by good lateral thinking. 

 

Whether was legal is a different debate  - and a very long one!!

[GreenMachine]

... But top team's capabilities to "fix it" are now way beyond anything that Team Lotus possessed in 1979. This is when all those hundreds of technical team personnel can really earn their keep.  We shall see.

 

DCN

 

The technical resources and capabilities are indeed on another planet by comparison.  However the ruleset has just taken away a lot of the suspension trickery that would otherwise have played some role in solving this problem (I reckon, anyway).

 

It will indeed be interesting to watch! 

[Nemo1965]

As an avid fan of Peter Wright, Colin Chapman and Lotus I will just say the same thing again  - the Lotus 88 had the capacity to solve all these problems by good lateral thinking. 

 

Whether was legal is a different debate  - and a very long one!!

 

But ah! The 88 presented all new problems by itself. De Angelis is reputed to be scared stiff by the car. I've read that there was a danger of air coming between the two chassis and it is said to have led to a mid-air pirouette around the axis... On top of that, I remember several interviews with Peter Wright, Nigel Bennet and Gerard Ducarouge, in which they stated that active suspension would have solved all the problems the Lotus 80, the Arrows A2 and the JS 19 had... but active suspensions are prohibited now, aren't they? It is shame because it would a synch now for the FIA to control ride-height (no more wooden four by fours in the pits!) and even to make, in the rain, certain ride-heights mandatory...

[Charlieman]

The way it was described to me was that once almost any bump or longitudinal deflection caused the front end of the car's lengthy undersurfaces to lose lift, the effective aerodynamic centre of pressure would race rearwards, the rear suspension would suck down, reach its bump limit and react, causing the rear of each undersurface then to lose effective suction.  By that moment the front end would regain enhanced effect and the aerodynamic centre of pressure would race forward once more. Whereupon the front suspension reacted that added load and the process would repeat - the CoP being out of control, flickering back and forth.

Much was made at the time of abrupt loss of downforce when skirts lost contact with the track. I always felt that this explanation was a bit of a distraction from the more fundamental problem. With venturi ground effects, the CoP will move forwards and backwards according to speed, even when the team has fully sorted out skirts.

 

No doubt there were similar porpoise problems with high mounted wings until teams prevented stalling by the front end of the car being pushed down too far. Remember all of the experimentation with anti-dive suspension systems?

[AJCee]

This was also discussed on the BBC Sport website in the comments section after the pre-season testing times. One contributor was lauded as some kind of sage for stating that Ducarouge had solved this issue with the JS11 by introducing pressure-release valves.
My memory may be wrong here, so happy to be corrected, but wasn’t the JS11’s initial problem much like many first generation ground effect cars in that it’s chassis wasn’t stiff enough for the downforce it created? (and not that the early season set up was written on a fag packet that had got lost…) Pressure-release valves were ‘moveable aerodynamic devices’ and therefore against the rules so not really a solution at all (mind you, sliding skirts were also moveable aerodynamic devices…). I’ve seen rumour that they were uncovered on the Ligier at the end of the 1980 season, but not seen anything to verify that.

[Henk Vasmel]

Funny. I remember it slightly different: that all ground-effect cars would suffer from porpoising, it was a matter of course and there were two ways to battle this: rise the ride-height (no, no, no, no), stiffen the suspension immensely or find some clever way to make the car less respondent to the undulations in the road. THAT was one of the clever ideas of the Lotus 88 after all, to haven an outer chassis with the so important sealing skirts that would be totally flexible and following the road while the inner chassis with the driver would be rock-solid... (BTW: I always found the rumour hilarious that Chapman all winter was trying and lobbying to get the diameter allowed for the underbody of the F1-cars diminished... yes diminished. To that dimension? Much more narrow than the the best cars of 1980 (The Williams, Ligier, Brabhams), more like that of the yet to be revealed slender Lotus 88...

 

Remember the famous line from Alan Jones who tested a totally-spring less Williams in 1980 and rather condemned the harsh drive. 'Why don't you sit on your wallet,' said Frank Williams. 'Why don't you give me something to put in it?' Alan retorted... Not only funny, but this story also underlined that porpoising and the need for an idiotic harsh suspension were relevant for more than the Lotus 88, the Arrows A2 and the Ligier JS 19... 

 

Yes, stiffening the suspension was one cure to porpoising, but the consequences of that are a very bumpy ride, and several drivers in those days began suffering from spine problems. Not the way to go.

There was also the theory that ground effect cars tended to fly after accidents and the subsequent landing made the results more damaging. (Villeneuve, Pironi, Mass in testing etc.)

I have been working on aeroelasticity at Fokker Aircraft for 15 years, starting in 1981, and I have learned that the non-linearities like stalling or hitting bump stops are not necessary for sinusoidal movements to occur, but it will stop the vibration from increasing up to levels where parts break when they occur. Then you get into the area of limit-cycle oscillations.

The vibration will actually have a complex value, including the damping which is negative in this case. That means the amplitude will increase after even a minute trigger, up to the level where a non-linearity is reached.

Basically it is an interaction between the (linear) stiffness of the structure and the changing aerodynamics due to the change of shape in the eigenmode. Solutions lie in the modification of the eigenmode, either shape or frequency, which indeed can be done by modifying the stiffness of the suspension. As seen above another way has to be found with less negative side-effects.

[Michael Ferner]

Interesting that the "twin-chassis" smoke screen still works - Chapman was onto something with that! (Not with the concept, that didn't work anyway, but his rhetorics of selling moveable bodywork as a "second chassis").

 

Anyway, I'm surprised to hear that F1 is re-introducing gound effects - what happened? is that a reappraisal of the whole idea, and if so what's the reasoning behind it, or are they just running out of ideas?

[Henri Greuter]

As an avid fan of Peter Wright, Colin Chapman and Lotus I will just say the same thing again  - the Lotus 88 had the capacity to solve all these problems by good lateral thinking. 

 

Whether was legal is a different debate  - and a very long one!!

 

 

But ah! The 88 presented all new problems by itself. De Angelis is reputed to be scared stiff by the car. I've read that there was a danger of air coming between the two chassis and it is said to have led to a mid-air pirouette around the axis... On top of that, I remember several interviews with Peter Wright, Nigel Bennet and Gerard Ducarouge, in which they stated that active suspension would have solved all the problems the Lotus 80, the Arrows A2 and the JS 19 had... but active suspensions are prohibited now, aren't they? It is shame because it would a synch now for the FIA to control ride-height (no more wooden four by fours in the pits!) and even to make, in the rain, certain ride-heights mandatory...

 

 

I confirm Nemo's statements about what he has read and posted about de Angelis and the behaviour of the 88. I hae read such too.

[Nemo1965]

Yes, stiffening the suspension was one cure to porpoising, but the consequences of that are a very bumpy ride, and several drivers in those days began suffering from spine problems. Not the way to go.

There was also the theory that ground effect cars tended to fly after accidents and the subsequent landing made the results more damaging. (Villeneuve, Pironi, Mass in testing etc.)

I have been working on aeroelasticity at Fokker Aircraft for 15 years, starting in 1981, and I have learned that the non-linearities like stalling or hitting bump stops are not necessary for sinusoidal movements to occur, but it will stop the vibration from increasing up to levels where parts break when they occur. Then you get into the area of limit-cycle oscillations.

The vibration will actually have a complex value, including the damping which is negative in this case. That means the amplitude will increase after even a minute trigger, up to the level where a non-linearity is reached.

Basically it is an interaction between the (linear) stiffness of the structure and the changing aerodynamics due to the change of shape in the eigenmode. Solutions lie in the modification of the eigenmode, either shape or frequency, which indeed can be done by modifying the stiffness of the suspension. As seen above another way has to be found with less negative side-effects.

 

Very interesting, your post. When I was about thirteen, fourteen I was the only F1-fan or motorsport-fan in my family and also at my school. (We are talking way before the Jos & Max Verstappen-days.) Coincidently, I have a lot of family working in aviation. One brother is a pilot, and a lot of my uncles worked in the aviation industry. At birthday-parties they would often amuse themselves by asking their slightly nerdy nephew about the newest inventions in F1. I remember distinctly that sometimes they could not believe some stories until I showed them the written proof. For example: that the whole F1-fraternity had not understood what Lotus had done in 1977 with the first ground-effect car. They could also not believe that Colin Chapman (a name that they at least vaguely knew) had build such floppy, flexible ground-effect car with the 79, when it should have been obvious that stiffness was THE conditio sine que non for such cars. 'Oh, Nemo, come off it,'  they would say, 'of course that Chap Chapman must have thought of THAT!'

 

All my uncles (at least from that side of the family) are dead now. But they would have been amused by the current F1-cars bouncing like Mexican show-cars at the straight... 

[Henri Greuter]

This was also discussed on the BBC Sport website in the comments section after the pre-season testing times. One contributor was lauded as some kind of sage for stating that Ducarouge had solved this issue with the JS11 by introducing pressure-release valves.
My memory may be wrong here, so happy to be corrected, but wasn’t the JS11’s initial problem much like many first generation ground effect cars in that it’s chassis wasn’t stiff enough for the downforce it created? (and not that the early season set up was written on a fag packet that had got lost…) Pressure-release valves were ‘moveable aerodynamic devices’ and therefore against the rules so not really a solution at all (mind you, sliding skirts were also moveable aerodynamic devices…). I’ve seen rumour that they were uncovered on the Ligier at the end of the 1980 season, but not seen anything to verify that.

 

the famous  "plouf" .....

 

I recall a story by Giorgio Piola who told that on one occasion he saw the evidence of that and how the people at Ligier were livid on him because of that.

 

There was also an edition of the legendary magazine Grand Prix International paying attention to that, if my memory serves me well, it was in the edition of Zandvoort 1980 or shorly therafter.

[nmansellfan]

 

Anyway, I'm surprised to hear that F1 is re-introducing gound effects - what happened? is that a reappraisal of the whole idea, and if so what's the reasoning behind it, or are they just running out of ideas?

 

Part of the reason is to help make overtaking easier, primarily by simplifying the bodywork / wing aero to help reduce the dirty air generated by the car, but still giving the cars reasonable downforce.  The key difference to the '77 - '82 GE though is that there are no skirts of any kind this time round.

 

At least one improvement is that the cars no longer run a massive rake angle, they looked terrible with (relatively) huge rear end ground clearance.

[mariner]

It's getting more deja vu by the day. Now ti's "solve porpoising by active suspension".

 

https://www.autospor...-issue/8572196/

 

Well done Wright and Chapman and their technical teams of the day!

[cpbell]

Part of the reason is to help make overtaking easier, primarily by simplifying the bodywork / wing aero to help reduce the dirty air generated by the car, but still giving the cars reasonable downforce.  The key difference to the '77 - '82 GE though is that there are no skirts of any kind this time round.

 

At least one improvement is that the cars no longer run a massive rake angle, they looked terrible with (relatively) huge rear end ground clearance.

Yes, as someone who still follows contemporary F1, my understanding is that the last few years saw both an increasing focus on "outwash" aerodynamics, wherein dirty air from the front of the car was forced away from the car laterally with some being induced into vortices and directed (by massively-complex bargeboard systems) to seal the sides of the floor.  Those teams that were most adept at this were thereby able to increase the "rake" angle of the cars to generate more underbody downforce - running the "tea tray" leading edge of the floor almost on the track surface, but with the diffuser at least 2-3 inches off the deck.  Obviously, if their vortices failed to seal the floor properly, this wasn't achievable, and some teams (notably Mercedes) didn't use such a steep angle.  This outwash idea, though, meant that the area of turbulent air, instead of heading upwards at an angle, spreads-out like boat wake behind the cars, meaning that, once a following car gets within 1 second or so, they hit a wall of turbulence.  This problem is further exacerbated by the front wings being very sensitive to turbulence and running close to the ground.

 

This year's rules, rather that prescribing boxes around the car in which no bodywork can be present, define a series of curves and profiles within an acceptable range.  This was decided-upon after a couple of yeas' research by a group comprising former Technical Directors and designers who drafted rules, then went away and acted as though they were still working for a team to determine where the opportunities were to flout the intent of the rules.  This years' cars have the following important aerodynamic changes:

 

1.  Front wing is simpler and higher off the ground, with large endplates.

2.  Aerodynamic curved flaps are used at the front, mounted to the uprights and curving over the front tyres from just inboard of the inner shoulder to condition the flow off the front end.

3.  Rims now have discs fitted to reduce turbulence.

4.  Bargeboards are much smaller and in one part only.

5.  Floor entry venturi tunnels under the sidepod inlets, together with the tunnels themselves and the diffusers have to conform to the accepted range of curve radii and profiles I mentioned above.

6.  Rear wings do not have separate endplates; the mainplane and flap must curve downwards instead.  Beam wings are allowed.

Edited by cpbell, 28 February 2022 - 13:55.

[Sterzo]

They could also not believe that Colin Chapman (a name that they at least vaguely knew) had build such floppy, flexible ground-effect car with the 79, when it should have been obvious that stiffness was THE conditio sine que non for such cars. 'Oh, Nemo, come off it,'  they would say, 'of course that Chap Chapman must have thought of THAT!'

A fascinating angle on a legendary development! Perhaps it's a reminder that racing teams were small operations with limited facilities, compared with aeronautics companies. Chapman, Wright and earlier the Costins were of course well aware of and had connections with the nearby British Aircraft Corporation (previously de Havilland). But perhaps they simply didn't have the resource to test their ideas so thoroughly. They were certainly aware of the need for increased rigidity, but (from memory) Wright was shocked by the downforce generated, which exceeded all estimates.
 

[Nemo1965]

A fascinating angle on a legendary development! Perhaps it's a reminder that racing teams were small operations with limited facilities, compared with aeronautics companies. Chapman, Wright and earlier the Costins were of course well aware of and had connections with the nearby British Aircraft Corporation (previously de Havilland). But perhaps they simply didn't have the resource to test their ideas so thoroughly. They were certainly aware of the need for increased rigidity, but (from memory) Wright was shocked by the downforce generated, which exceeded all estimates.
 

 

Of course I am not in any way slagging off the achievements of Wright, Chapman and so forth. The discussion about the 'floppy' Lotus 79 came about halfway 1979, when Williams and Ligier 'out-Lotused 79' the Lotus 79. If I remember correctly, even Mario Andretti told that year or not much later, he had stressed (haha) to Chapman, that they had to reinforce the Lotus 79... and according to Mario, Chapman did not listen because he had his mind already on the next wonder-car (which was the Lotus 80 and wasn't!)