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#1 MarkWill

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Posted 20 January 2003 - 15:34

Hi,

I was looking at theZandvoort Circuit History site, and it ocurred to me that over GP history the cars went from having streamlined cowls covering the engines, to being open-engined, then open but with a scoop, then back to being enclosed. Is this due to rule changes, or the need to cooling?

Looking at the picture of Jo Bonnier's BRM in '59, it seems have a small ridge along the back - surely this wasn't for aerodynamic purposes....was it (if so, I'm curious to know how they arrived at this design)? The Cooper-Climax of Jack Brabham had a dorsal fin, a bit like those found on the D-type Jaguar - was this for straight-line stability?

Lots of questions (again) about these fascinating cars.

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#2 Wolf

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Posted 20 January 2003 - 17:15

Mark- one should also not forget the 'downforce' engine covers that were used shortly in '69, when ban on wings came into effect...

#3 MarkWill

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Posted 20 January 2003 - 22:03

Hi Wolf,

I missed those - when were they banned? I'm really intrigued about the ridge on the BRM, because it isn't an obvious shape. I was wondering if it wasn't to accomadate a part of a cooler or something. Maybe Doug knows..................

#4 Wolf

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Posted 20 January 2003 - 23:41

Mark, they weren't banned but made redundant with reintroduction of aerofoils (since the aerofoils were not to be high strutted, I figure the covers would disturbe the airflow*)... I think bare-engined trend had more to do with early 3l cars that were rarely light enough (hell, BRM H16 engine with gearbox and rear suspension attached, IIRC, was over minimum weight by itself!), so excessive metal was avoided. Then came scoops to increase pressure of the air fed to the engine (ram-effect). Only then, I guess streamlining came into fashion again.

* although one could argue they'd nmake bi-plane section in the middle... :lol:

I'm fairly ignorant about the purpose of dorsal fins, but I guess they might have had the purpose of introducing high speed oversteer (back then, it was reckoned the long tails of Italian cars had the same effect)- a desired thing because of 'controlability'. But one should not discount the possibility of stiffening effect of those fins (just like the steps on sides of cars) being also a factor in their application.

#5 Doug Nye

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Posted 20 January 2003 - 23:58

The original BRM Type 25 prototype body had a 'headrest' ridge formed into quite a prominent tail fin but it was speedily ditched in favour of a simple faring to the head-rest - or neck-rest - which had no measured aerodynamic effect at all. These things were just a styling motif really, though the shape helped stiffen the tail cowl panel which with BRM's use of 18 and even 20-gauge elektron sheet could certainly do with all the stiffening it could get. Many of the 1950s - and earlier - tail fin designs owed more to style and hunch than to aerodynamic study and testing. Mercedes used a tunnel - see Karl's superb works - Lancia toyed around - Connaught had a firmer grasp of aerodynamic niceties than most - Frank Costin worked his black arts on Lotus Mark VIII onwards - then there's Deutsch & Bonnet and the French practitioners, and going back pre-war there's Wunibald Kamm and Paul Jaray and Prof Zarkov and Flash Gordon and..... etc etc etc

DCN

#6 Wolf

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Posted 21 January 2003 - 00:07

Doug, I think Pomeroy reflected on this high speed oversteer and the cause of it (that's where I got the Italian long tail thing) in 'Design & Behaviour', I think he even mentioned the discussion with Chapman on the subject. And when one looks at the fins like on Coopers, they give extra aerodynamic drag behind the centre of the car, which pushes the tail out. Admittedly, the higher the speed the bigger the drag (so far so good, for my theory), but alack also the 'exposed' area of the fin (one cannot assume great angles of attach with high speed, because turning radii are great. Sounds like rather crude (too strong a word, but can't think of a better one) solution to induce this high speed oversteer. Just my 2c worth, though. :blush:

#7 MarkWill

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Posted 21 January 2003 - 04:48

Wolf, Doug,
Thanks for the info - Doug, if you're right, then thank heaven for the lack of wind tunnels in those days - the end result was very stylish. Odd to think that Mercedes had already showed the world which way to go in car design by using a wind tunnel, yet no-one else really did the job seriously iuntil sometime later (were the Ferrari Sharknose cars designed using a wind tunnel - they look as though they were quite a slippery design). Was the 18 or 20 gauge sheet unsupported? Thats very thin - you could almost deform it just by blowing on it.

I wondered if the cowls were left off to assist cooling?

Ref. the fin - I don't see how this would work on the Cooper regarding inducing oversteer (and, presumably, neither did they because they ditched it). Is it possible that the Cooper was a bit unstable in a stright line (because as far as I can see, thats where the fin would be the most use). What I mean is, presumably on a front-engined car you would benefit from adding weight behind the wheels to counter the effect of having the motor so far forward and this would do the job of inducing high speed oversteer (I think), but on a mid, or rear-engined car, the weight is already there so I can't really see the benefit. Too bad we can't ask the designer what he was thinking of. Perhaps the idea was borrowed from the Jaguars (as I mentioned, wasn't the D-type using a fin at around the same time, and isn't it possible that this was a borrowed idea?). How long did the Cooper sport the fin for? Zounds, Dale, this looks like a tricky one...............

#8 Ray Bell

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Posted 21 January 2003 - 08:26

Wolfie mentions the Lotus fins being the subject of some Pomeroy discussion...

I think it was, and the point was that the Lotus 11 rear fins were intended to increase understeer by keeping the car wanting to stay straight.

Those were the days of intentional gross understeer... days we're glad have gone.

You will find that many cars were made with engine covers but ditched them in the practical scenario of the pit stops of practice... and left them off.

#9 MarkWill

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Posted 21 January 2003 - 13:30

Intentional gross understeer :confused: Thats a new one on me, but I guess that it was considered innovative at that time (although, again, I would have thought that you could achieve the same result through suspension settings), unless the car had a natural tendancy to oversteer???

#10 Wolf

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Posted 21 January 2003 - 13:42

Mark, let me explain what I meant with that oversteer thing. When turning, apparent wind* (sorry about sailing term, but 'tis most appropriate) shifts inside the corner, pushing the car 'out' of the corner. Exposing the extra surface at the rear (like fin) will increase 'push' on the rear, hence increasing the oversteering tendency (or, at least, decreasing understeer). BTW, I think the last GP Cooper to have sported the dorsal fin was T70 (from '63, IIRC)...

* to show the relevance of apparent wind, here's a bit of trivia- non-displacement sailboat (like catamaran), on a broad reach can sail faster than the (true) wind driving it; thanks to, You guess, apparent wind

I could argue how effective this fin would be post '61 (if at all, I reserve the right to be wrong), when not only 1.5l engines, which never developed enough torque to allow regaining full controll of the car with throttle*, but saw advent of new driving technique to which, I'd venture to say, this wasn't all that desirable feature. In '61, Moss started using trailbraking- and I don't think extra 'push' (or any destabilizing factor)would be desireable on unladden rear wheels on corner entry...

* a crucial thing with high-speed oversteer, which one would (if skillfull, or speed-happy enough) control by applying a bit of opposite lock and throttle modulation; or use it, in case of Greats, by on purpose breaking of traction at the front wheels and when oversteer kicked in, travelling through corner in controlled four-wheel drift

BTW, there was a surprisingly little change in weight distribution between front and rear-mid engined cars- speaking off top off my head, I would say Pomeroy mentioned 2-3% increase at the rear with the latter. And I'd say that polar momentum hasn't dropped significantly either, to make cars much more unstable (tanks went to the front, remember).

P.S. If I was to stetch my theory to 'unseen heights' (of ridiculousness :p), I could argue that unfaired engines og post '66 time could have the same effect, but not by virtue of extra surface to increase 'rear push', but by increase of Cf- drag coefficient. But, as I've said, the faster one goes apparent wind is stronger, yet the shift of it is smaller... *shrug*

BTW, I don't think Doug has stunned You enough- 'twas full scale windtunnel, not for models... :eek: But I don't think technology would make all that difference- just bear in mind that Mercedes, despite their scientfic approach and windtunnel failed to make use of great 'lead' (piece of info), regarding the air-brakes*, Moss provided to them at Le Mans (admittedly, they had other things on mind, after it :|).

* he forgot to retract the air-brake for one corner and noticed he could go faster through it, with the brake on than withou it. The first movable-aerodynamic device (for creating downforce, rather than drag) was born, and Moss used it to his advantage, but everybody failed to realize the importance and true nature of this find.

#11 Ray Bell

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Posted 21 January 2003 - 20:47

Originally posted by MarkWill
Intentional gross understeer :confused: Thats a new one on me, but I guess that it was considered innovative at that time (although, again, I would have thought that you could achieve the same result through suspension settings), unless the car had a natural tendency to oversteer???


Actually, all paths to achieve it were eagerly pursued through to the fifties...

I think you need to have a read of The Design and Behaviour of the Racing Car by Moss and Pomeroy to catch up on this...

They mention M-B being 'caught up in this theory as much as anyone else' and date the whole thing back to pre-war ideas. So Chapman wasn't being innovative.

#12 fattogatto

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Posted 21 January 2003 - 21:40

Wolf,

Most interesting discussion. I will stick my neck out here and disagree with the sailing analogy. Apparent wind is a very real phenomenon in sailing, but I do not think it applies here. On a boat, due to the ability to swing the sail relative to the keel, this distinction must be made. However, with the dorsal fin fixed relative to the car's longitudinal axis, the phenomenon involved is "relative wind."

Dorsal fins add straight line stability and decrease oversteer, in that as soon as the car yaws, due to either aerodynamic forces or driver input, the "outside" face of the fin is presented to the realtive wind. This relative wind tends to push the rear of the car back in line.

This aero aid was developed (in part) during the late 1950's and early 60's by the manufacturers of the first trans-sonic and supersonic fighters. Several aircraft in developemnt, notably the F-105 Republic Thunderchief and the Electric PA-1A had high speed stability problems in the yaw axis. It was found that by adding a dorsal fin to the bottom of the fuselage it helped damp out the yaw tendencies and provided the stability.

Dorsal fins lately have been developed for those cars involved in high speed ovals or high speed tracks like Le Mans. Oversteer on an oval is pretty much undesirable so these aids were a help to keep the car under control. Also it is a method of providing for high speed stability without changing the low speed characteristics of the car. An added benefit also may be to clean up some of the airflow to the rear wing.

#13 MarkWill

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Posted 21 January 2003 - 21:59

Thanks Ray - I'm looking out for the book on e-bay and amazon.

Well, if nothing else, this thread has lead to an amusing lunchtime discussion with my colleagues about "apparent wind" and a new management style :) but once I re-read your post, Wolf, it makes sense. Now, Wolf, you talk of oversteer, and Ray talks of understeer, but if I understand correctly you are both referring to the same thing - namely that the goal was to get the front and rear wheels to break to get the car to four-wheel drift around a corner. My question is, which was it - understeer first, then oversteer, or the opposite?

Incidentally, the Mercedes wind tunnel story is interesting - when was it built, and where? One person I work with thinks that it was a leftover from pre-war racing; is it the same one that was used by Porsche/Auto Union? The air-break/aerofoil story has triggered a vague memory - weren't there sportscars in the fifties that ran with nose-ducts that did the same thing (just a vague recolection.....)?

If the current thought of the period was to use a fin, I wonder what lead BRM to drop it on the Type 25 (wouldn't their car have benfitted more than others from this)?

I guess that the cowls only became necessary when their aerodynamic benefits were considered to be important - circa late-seventies.

#14 Roger Clark

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Posted 21 January 2003 - 23:09

I have to admit that Wolf's theories about high speed oversteer are completely new to me. My understading is that the fins on the D-type, the Mark VIII Lotus and the orginal B-Type Connaught were there to promote high speed understeer (as fattogatto says). This is what Pomeroy wrote in Design and Behaviour, not the opposite (page 162/163).

Ten years later, the reason many 1 1/2 litre cars had no engine cover was cooling, particularly of the injection nozzles; te early 3-litre cars had no engine covers simly because the engines were too bulky to fit bodywork around them - try to imagine a cooper-Maserati with rear bodywork.

When high wings were banned in 1969, the rules said that aerodynamic devices were only permitted it they were part of te bodywork, hence the downforce engine covers. This rule proved impossible to enforce and was soon abandoned.

#15 Wolf

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Posted 21 January 2003 - 23:39

Mark, the apparent wind is the only relevant thing, even for cars... Even more so, despite wind not being propellant but creating drag or lift- because speeds are much higher (here we can safely disregard true wind, and hence is car's speed is the only component of apparent wind). In case of straight line travel, this fin will indeed correct rear end of the car. I fear You got the wrong impression of 'apparent wind', so I made a small sketch to illustrate it. And to make analogy (here we'll disregard true wind and speed vectors), and say this could very well be the apparent wind on the car in sharpish left turn (pointy end would be the front end).

Posted Image

Now, if I durst be lazy and use the same sketch for the car, I'll depict the idea behind my reasoning. Adding the fin would increase are at the rear of the car, but will also move the 'point of application' (Angriffspunkt) of aerodynamic force arrears (we could assume it generally to be centroid of exposed area). Now if we were to compare situations, things would be like shown in the first pic. Yet better comparison would be in second pic, which shows force in the case of fin moved to point where no fin force was applied. The obvous thing now is 'reduction momentum', which if we remeber the case being car turning left, 'pushes' the rear out, hence it promotes oversteer (or reduces understeer).

Posted Image

But I would disagree with Ray, on matters of general practice in '50ies. I can only remember W196 and Chapman's modifications to Vanwall (and early Lotus, pre 18, cars) to be 'notoriosly' understeering. Italians had afinity for final oversteer. And Mercedes had went trough great deal of pains to remove the understeer (and Moss, when taking Vanwall for a spin after Chunky's redesign of suspension, IIRC, just said the front roll bar was to be removed). The trouble with understeer is that one needs to drastically slow down to regain controll, but artificially induced understeer (abrupt and violent turn on the wheel) was sometimes used to slow the car down if braking point was missed, because it also scrubbed off speed at great rate*. I'll enclose the graph from 'Racing Driver', and just remark that I guess D curve might very well be W196...

* and as DSJ so vividly described it in case of Moss- even in esses, where he provoked understeer in an oversteering car (300SLR) to slow down through first bend, and when the undesteer wore off (otherwise dangerous) snap of the rear end-out rotated the car in the next bend. The tricky part was catching the 'snap' and utilizing it to turn in, but that's what made the difference between Greats and 'mere' greats...

http://members.atlas...om/wolf/dj2.jpg

Roger- I think the understeer Pomeroy and Fattogatto speak of is 'static' (initial) understeer, as in factor of straight line stability (extreme left of the graph above); not the 'actual' (cornering) indersteer.

#16 Roger Clark

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Posted 21 January 2003 - 23:56

Originally posted by Wolf

Roger- I think the understeer Pomeroy and Fattogatto speak of is 'static' (initial) understeer, as in factor of straight line stability (extreme left of the graph above); not the 'actual' (cornering) indersteer.


I 'm sure Pomeroy, at least, was talking about both.

I'm note sure what you mean by "the extreme left of the graph". The graph shows the side thrust a tyre is able to withstand for different slip-angles. The left hand part of te graph shows a left hand bend. The implication of the graph is that the tyre is able to withstand maximum side thrust when running at a slip angle of about 15 degrees. This is why the cars of the 1950s were cornered in such satisfying slides.

#17 Wolf

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Posted 22 January 2003 - 00:15

Roger, are You sure You didn't by chance open the file http://members.atlas...om/wolf/dj3.jpg ?!? Or did You check the post before I edited it, and replaced (wrong)image with link to correct one? Sorry about the confusion, but click on the link if You haven't done so. :blush:

#18 Doug Nye

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Posted 22 January 2003 - 00:41

I regret to say I think there's rather a lot of obscure nonsense being perpetrated in this thread...given more time (which I don't have presently at 00:41 and still with hours of work ahead of me) I would be more specific...

DCN

#19 fattogatto

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Posted 22 January 2003 - 00:47

Originally posted by Wolf

Roger- I think the understeer Pomeroy and Fattogatto speak of is 'static' (initial) understeer, as in factor of straight line stability (extreme left of the graph above); not the 'actual' (cornering) indersteer.


Wolf,

I still beg to differ. Although your diagrams are most helpful, I believe the one showing the two vectors (with & without fin) is misleading. While I totally agree that the addition of a fin will increase the rear area upon which the wind (apparent or relative) will act, the "point of application" will not move. All forces acting upon the vehicle will act around the center of gravity. The center of pressure, however, will indeed move rearward, and, in doing so, will provide for a greater moment arm, therefore giving a greater tendency for the rear end to fall back in line with the front: understeer. This stability is dynamic, and continues throughout the corner. If the car is held exactly in the same drift angle the stability effects will be constant, but still tending to understeer.

Our basic point of disagreement is in the direction from which the wind comes. I posit your diagrams are correct for a car in a right turn not a left hand turn. In considering one of those great pictures from the early 60's showing a large car in a beautiful 4 wheel drift, the nose of the car is always pointed into the turn, and therefore, the relative wind will be coming from the outside of the turn. i.e. in a right hand turn the relative wind is from the left quarter, and vice versa. Therefore, the relative wind will tend to straighten the car out, not over-rotate.

Think of a rally car in a broad-slide. With the car pointed 75 degrees to the direction of travel, where is the relative wind?

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#20 Wolf

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Posted 22 January 2003 - 01:13

Fattogatto, regarding 'point of application', we might argue on semantics, but basically are in accord in regard of end result, I say drag is in 'centre of pressure' and You say drag is in centroid, coupled with 'reduction momentum'.

Re the direction of apparent wind- it always 'oppposes' travel (speed)- just observe the phenomenon while riding the bike; You can drive in circle and always feel as driving against the wind. So, in corner I see no reason to be otherwise; but Your example is a bit misleading. Assuming the situation of normal 'angle of attack' (or attitude of the car), apparent wind will always push the car out. Speaking of numbers, I remeber Moss mentioning figure of 8/100 (speaking w/o any of my books at hand, can't check it out, but 'twas in 'All but my life') gradients of drift. So with that in mind, I think we're safe to assume that drift will somewhat diminish the angle of apparent wind, but not change its direction from wind to lee (in my picture).

Doug- we're looking forward to being put straight... :)

#21 fattogatto

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Posted 22 January 2003 - 01:17

Wolf,

We'll just have to agree to disagree. The difference between the boats and bycycles versus the drifting car is that there are no slip angles involved in the former.

#22 Wolf

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Posted 22 January 2003 - 01:54

Fattogatto- You're right about the bikes, but boats do have slip angles of a sort (they even have something like under- and oversteer). Actually all boats have a 'drift' when under sails...

#23 Marzal

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Posted 22 January 2003 - 03:02

I always tought that fins were there to reduce drag. They shape the back of the car (the most drag-inducing part of the car) such as to minimize the body-induced vortices.

Don't you remember those '50 Alfa Romeo BAT prototipes with their huge fins?

#24 Roger Clark

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Posted 22 January 2003 - 06:22

Originally posted by Wolf
Roger, are You sure You didn't by chance open the file http://members.atlas...om/wolf/dj3.jpg ?!? Or did You check the post before I edited it, and replaced (wrong)image with link to correct one? Sorry about the confusion, but click on the link if You haven't done so. :blush:


Yes, I saw the post before you edited it.

#25 Wolf

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Posted 22 January 2003 - 16:52

Apparently, I have made an error in 'reading' Fattogatto's post, and should blame it entirely on him- I had been thrown off, with that rally comparison. :p

Fattogatto- in case of cars pointing inside the corner (apparently, drift gradient outweighing turn 'gradient')- You are right: wind and lee indeed switch sides and in that case my pictures would show right turn, and momentum would increase understeer (or decrease oversteer). Sorry it took me a bit to catch up, but my mind sometimes gets stuck in a 'rut' and I miss most obvious things. :blush:

#26 Wolf

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Posted 22 January 2003 - 18:29

Heh, I just used the boat thingie to visualize the difference beteen perceptions of the first pic... And to confirm it with Fattogatto, to see if it is indeed what he meant.

Posted Image

Curve 1 would be left constant radius turn I had in mind when drawing a sketch (and I'd say apparent wind is still OK for that situation). Curve 2 would also be (this time right) constant turn radius on which car would travel without drift (although, I have rotated it a bit, not to make second case too extreme in terms of requited drift). Obviously, to have same apparent wind, one must have drift angle as shown in pic, which results in trajectory 3, which is (I'm not sure about the name, but think it is Euler's, not Archimede's) spiral, not circular trajectory.

#27 fattogatto

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Posted 22 January 2003 - 18:39

Originally posted by Wolf
Fattogatto- in case of cars pointing inside the corner (apparently, drift gradient outweighing turn 'gradient')- You are right: wind and lee indeed switch sides and in that case my pictures would show right turn, and momentum would increase understeer (or decrease oversteer). Sorry it took me a bit to catch up, but my mind sometimes gets stuck in a 'rut' and I miss most obvious things. :blush:


Wolf,

That is my point exactly, and, entirely. I can not really imagine a situation (restricted to 4 wheeled, non-ocean-going vehicles) where a car, in a drift - which normally requires the momentary nominal heading of the car to be different from the momentary direction of travel (course, if you will) - will not be pointing into the turn. This would be the case excepting the presence of monumental understeer. One might assume that in such extreme cases, the rear of the car could indeed be slightly upwind of the front, but I don't feel this would be enough of a difference to actually induce oversteer.

As to the second post with drawing . . . . . . it gives me a Greek headache.

#28 David Beard

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Posted 22 January 2003 - 18:40

Originally posted by Wolf
Obviously, to have same apparent wind, one must have drift angle as shown in pic, which results in trajectory 3, which is (I'm not sure about the name, but think it is Euler's, not Archimede's) spiral, not circular trajectory.


Euler was the bloke who came up with the theory on the crippling of struts, surely. (the one that F1 designers ignore and insist on using push rod suspension instead of pullrod)

#29 oldtimer

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Posted 23 January 2003 - 01:34

If the Mercedes designers who penned those stylistic headrests could see this thread, there would be plenty of :rolleyes:

#30 fattogatto

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Posted 23 January 2003 - 01:48

Wait-a-minit, oldtimer. Maybe Mercedes was following the age-old adage of:

"Better to look good than to be good!"

Which leads to another aspect of the dorsal fin discussion. I personally think they look terrible - like something Captain Nemo would put on the Nautilus.

As to the issue of engine covers that was breached earlier: as with my March, they found the heat issue was a factor when the factory tried to fabricate an effective engine cover that would provide proper airflow to the injector stacks. The increase in engine bay temperature was critical so they decided to remove the cover altogether. (Looks better, anyway)

#31 oldtimer

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Posted 23 January 2003 - 06:48

It wasn't the Mercedes guys who followed the adage, because they were good. On the other hand, it could apply to some of the not-so-few who followed their styling lead. :)

#32 Roger Clark

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Posted 23 January 2003 - 06:56

The W196 shape was compromised to meet the needs of the marketing department.

#33 Ray Bell

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Posted 23 January 2003 - 07:53

Just in case I've been misunderstood... Pomeroy spoke of the promotion of understeer from beginning to end of the corner...

The idea of converting that understeer to a four wheel drift or having progression to oversteer was not on the cards, according to the 'understeer theory' on which he comments... as Roger has posted.

And I agree with Doug...

#34 Roger Clark

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Posted 24 January 2003 - 23:46

If I may summarise what I understand from the writings of Pomeroy and Jenkinson:

Most Grand Prix cars from 1937 were designed to understeer on the limit. The Mercedes W125 was the first car to be designed with this characteristic. Of course, with the power available in those cars, oversteer could be generated by use of the throttle which would reduce the grip available to the rear tyres. The four wheel drift, which first appeared in the late 1930s was actually an understeer condition with the front wheels pointing into the corner.

The 1954 W196 was designed according to these theories and it was excessive understeer which caused Fangio's problems at Silverstone, not lack of visibility.

In 1955 the W196 was modified to oversteer at the limit. During that season Fangio and Moss developed new driving techniques which enabled them to make the most of these characteristics. These techniques demanded extreme sensitivity and help explain why the gap between those two and their team-mates was so much larger than it had been between Fangio and Kling the previous year.

The techniques also demanded that the car had a surplus of power which could be applied at the crucial moment to balance the car. The Maserati 250F had always been an oversteering car, but did not have the necessary power surplus until 1957 when Fangio used the same techniques to great effect, most notably at Rouen.

#35 Wolf

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Posted 25 January 2003 - 00:23

Originally posted by Roger Clark
The W196 shape was compromised to meet the needs of the marketing department.


Would You mind expanding a bit on the subject, Roger? :)

#36 Roger Clark

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Posted 25 January 2003 - 00:42

Originally posted by Wolf


Would You mind expanding a bit on the subject, Roger? :)


Denis Jenkinson, comparing the W196 and the streamlined Connaught:

"The Mercedes-Benz was not so strictly functional in its lines, pandering in small ways to the styling department, the publicity department and to practical knowledge as regards racing cars. Whereas the front of the Connaught would have done justice to a fighter plane, the Mercedes-Benz was styled to have a similar appearance to their production sports car. The Connaught made no concessions to the requirements of te tyres, demanding tht te tyre manufacturers should be capable of producing a tyre that would stand up to the of racing without having the benefit of te outside air to cool the rubber. Mercedes-Benz, on the other hand, were prepared to upset the airflow along the bodywork and cut large holes in front of the rear tyresto allow some cooling air to enter the body. In a similar way they had air scooops for taking cold air into the cockpit, and other holes for letting hold air out of te engine compartment and for the exhaust pipes to protude through."

When the W196 was tested at Reims before its debut, it had a chrome three pointed star in te radiator intake. Tese were removed for the race, but reappeared at the British Grand Prix.

#37 Wolf

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Posted 25 January 2003 - 00:56

Thanks, Roger. :)

#38 MarkWill

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Posted 25 January 2003 - 02:23

And Thanks everyone to date. I recognize that there are aspects of this thread that might belong more in the technical forum, but the time and trouble you've all gone to has been impressive. I'm still looking out for a copy of The Design and Behaviour of the Racing Car before I can add my own 10 cents worth (or ha'penny worth, for those who know what it is).

Still curious to know about the Mercedes wind tunnel - I've looked on the 'net but there's no info. on its history, and unfortunately the people I know in Germany all work for Dornier. I'll re-ask the question - was this a pre-war facility, or was it new and purpose-built to test mercedes cars?

#39 Wolf

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Posted 25 January 2003 - 03:30

Don't know about the tunnel Mark, I think no details were mentioned in 'Design and Behavoiur', but there must've been few wind tunnels in Germany (I know there was one in Desau in late '20ies)...

BTW, I went for a quick look for a copy of aforementioned book online. Good grief, what happened to book prices?!? I got my copy for 10 or 15 quid (last year or so), now the cheapest copy is 90$ (I've even seen +200$ copies)?!?

BTW, You'll find Tech Forum more suitable and receptive for current F1 technology than anything else...

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#40 Roger Clark

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Posted 25 January 2003 - 08:23

Karl Ludvigsen, in "The Mercedes Benz Racing Cars" says "The nearby FKFS (Research Institute for Motoring and Vehicle Engines) was used for test of a one-fifth model of the proposed shape", and later "No wind tunnel tests of the full-sized body had been made before the day early in March 1954" (for the first tests of the car).

He later says that at Monza in 1954 coasting tests were done to calculate the aerodynamic efficiency of the bodies. I can find no further mention of wind tunnel work.

The results of the Monza tests were:

Open wheeled body: Frontal area 11.7 sq ft, coefficient of drag 0.62
Streamliner: Frontal area 13.4 sq ft, coefficient of drag 0.43

#41 MarkWill

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Posted 26 January 2003 - 13:39

Thanks Roger,

I have contacted some people at Dornier and asked them to hunt around for more info. The FKFS subsonic facility has been kept very modern, but hopefully there is an archive of older tests. From a personal point of view I'm curious to see what sort of testing they did in those days (what they were aiming for in terms of results, and what they were looking at). Re. the three pointed stars removal and subsequent reappearence, you don't happen to know why this became acceptable again by any chance (or was it for patriotic reasons?).