Dan Gurney'S Accident

[Autumnpuma 0]

In 1971, while I was still sucking the teat and soiling my nappies, Dan Gurney affixed a piece of sheet metal to the trailing edge of a race car's rear wing and invented the Gurney Flap. This little device has been widely used on race cars, airplanes and helicopters since then. This ingenious device causes a bubble of air to form right at the trailing edge of an airfoil. On a race car, this little bubble has the effect of increasing the size of the airfoil (wing) and, as a result, increases downforce generated by that wing. With very little drag. Like I said, ingenious.

Red Bull has one affixed to their diffuser.

This is significant because the length of the diffuser is limited by the rules, but with a Gurney Flap on there the diffuser suddenly becomes longer...and generates quite a bit of downforce. As with everything F1, there is more to Red Bull's speed than this.

They are also blowing their diffuser. Basically, their exhaust exits low and blows over the top and bottom of their diffuser. An old concept, but one that Newey has always liked. Blowing the diffuser on the top and bottom does two things...the bottom makes the air flow faster below the diffuser, creating a lower pressure area that generates downforce and the top make the air go faster over the Gurney Flap. As I said, blowing diffusers were common in the '80s and '90s but teams stopped doing that because in the 90's the engine suppliers wanted a shorter exhaust (remember Ferrari's top-exiting exhaust?). It appears that the new engines can have the longer exhaust so Newey has run back to the blown diffuser idea.

Blowing a diffuser has problems, though. You get heat from the exhaust blowing on the inside edge of the rear tyres and you get an uneven flow of air over a lap because the air coming out of the exhaust is dependent on throttle position (the faster you're going the more air...the slower you're going the less air). This explains perfectly why the Red Bulls were the only cars able to take the fast Turn 8 in Instanbul flat. The other problem is that you need a higher rear wishbone assembly to accomodate the lower exhaust. You also need ceramic or gold foil coating on the rear suspension bits to prevent the carbon fibre from melting. None of these problems are insurmountable, but some teams with a low wishbone assembly will have a big redesign ahead of them to match Red Bull.

Add all of this to the Renault engine's better fuel consumption and you get a good explanation of the Red Bull's speed. (Remember, greater fuel efficiency means less fuel in the tank...lighter car=faster car and lighter car=the ability to run a lower ride height setting).

It will be interesting to see which teams will adopt Red Bull's system.

[HandyNZL 1]

I'll have you take that back.....Dan sat on the Armco watching Bruce and Denny test a little strip on the back wing of their Can Am cars and noticed how much better they were at handling the corners....the next event they were all at was a Formula 1 race, and Dan had the strip on his wing....Bruce had only been interested in it for Can Am....and hence we now have a Gurney strip...

...I need to find the reference to that story in one of my books...or maybe it was in Dad's....for ya.

Otherwise, carry on, old chap.

[Persevere 0]

Damn, you're both going to have me scrambling through my library to check on this one. Still, any thread that discusses D. Gurney, B. McLaren and D. Hulme makes this old dog feel young again.

Craig: good to see you back.

[BradSpeedMan 6]

I'll have you take that back.....Dan sat on the Armco watching Bruce and Denny test a little strip on the back wing of their Can Am cars and noticed how much better they were at handling the corners....the next event they were all at was a Formula 1 race, and Dan had the strip on his wing....Bruce had only been interested in it for Can Am....and hence we now have a Gurney strip...

...I need to find the reference to that story in one of my books...or maybe it was in Dad's....for ya.

Otherwise, carry on, old chap.

Hi Handy, where have you been, nice to see you back. cheers

nice insight Mike

[Schumikonen 2]

Thanks Mike,I wanted to know about how this blown diffuser work and now you post this with even more info than what I wanted to know, it's great to have posts like this one from time to time.

If that "wing' makes the diffuser bigger, does that means that RB's diffuser it is actually smaller than other team's diffuser in order to accomodate this device? I gess that if another team with a full size diffeser want to imitate this they will have to reduce their diffuser size to be with the rules.

[HandyNZL 1]

Thanks Mike,I wanted to know about how this blown diffuser work and now you post this with even more info than what I wanted to know, it's great to have posts like this one from time to time.

If that "wing' makes the diffuser bigger, does that means that RB's diffuser it is actually smaller than other team's diffuser in order to accomodate this device? I gess that if another team with a full size diffeser want to imitate this they will have to reduce their diffuser size to be with the rules.

No, the diffuser should be much the same size accounting for suspension layout and chassis shape - they will just be generating more downforce. A Gurney Strip (or Flap as Mike likes to call it, which I believe is really a misnomer as it doesn't flap at all - unless it comes off of course) is generally just a piece of right angle aluminium or composite attached to the wing element, which as you can imagine will cause considerable drag, but in this case it is wanted drag, as it turns a wing, say 250mm wide, into one offering the same downforce as one, say 350-400mm wide, but of course you are not carrying the weight, nor needing to account for additional size of any aeropackaging.

Here is an example on a Swift DB4 Formula Atlantic, most noticeable on the front wing, though you can make one out on the lower wing foil, and the top foil has one that is painted yellow.

The technology involved in a Gurney Strip makes complete sense today, but when aero on cars was being worked out back in the 60's and 70's, it was quite a revelation. Often its the simplest ideas like this that turn out to be the best, same as the ducting of the air over the wing, which is actually counteracting the Gurney strip.

A lot of aero was sort of just "found out" by the drivers back in the day. For example in testing one of their M8's for Can Am, Bruce McLaren noticed that the he was handling better in testing after having come into the pits and been refuelled with the petrol flap not secured back in place...as he went down the straight he would watch this flap open up the faster he went, and in high speed corners this flap would stay up due to the wind pushing it up from underneath, giving him better front end handling. He stopped in at the pits, got out of the car, went to his toolbox (would you see a driver do THAT today??), pulled out a pair of tin snips, and attacked the bonnet on the car around the area of the petrol flap, opening up the hole. Everyone was kind of WTF (though they were a bit less gruff than that back in early 70's in England, it was more like, "Old Boy, what the blazes do you think one is doing there?") as Bruce jumped back in the car, and then went and set several lap times considerably quicker than he ever had before.

[HandyNZL 1]

Damn, you're both going to have me scrambling through my library to check on this one. Still, any thread that discusses D. Gurney, B. McLaren and D. Hulme makes this old dog feel young again.

Craig: good to see you back.

Good to be back....

Thems were real men back then. Nothing but poofs these days

[HandyNZL 1]

Hi Handy, where have you been, nice to see you back. cheers

nice insight Mike

Good to be back...where have I been....well sorting a bit of Sh#te out in the real world what with having started up my own business and all, and any other spare time has either been with my little girl, or tinkering on our now seemingly ever growing collection of Historic Formula racecars.

Pop's 1965 Formula 3 Cooper

My 1973 Formula Ford Lola T340/2 (which I claim is only as old as me as it's first race was two days before I was born! Log books make for interesting reading)

Pop's 1974 Formula Ford Lola T342 (just got into the country start of June - fired her up once, sounds very crisp with a Jay Ivey motor and nice stainless headers) (pic taken at it's old home in Spokane, Washington)

And now looking at getting a 1976? or 1977? Formula Ford Lola T440 (pic taken in it's current home in New York) - the old man is keen on this as he reckons it will give him an edge over me......... yeah, right.

Don't know how we intend racing four cars at once between two drivers when the Juniors and Fords race in the same race, nor how we will race three Fords at the same time when the Juniors and Fords don't get combined. The former owner of the black FF has been invited to race it at the NZ Festival of Motorsport Celebrating Chris Amon next January - he actually never raced it in the States, as he has two FF2000's.

Tell ya what...you get one car, and you just can't stop getting another...and another....and another....better than investing in BP stocks at least....

[HandyNZL 1]

The more I think about it, the more I think the story is spoken about in Phil Kerr's most excellent book "To Finish First" - if memory serves right, Dan was there because he was driving the Can Am car, so that is why he knew about it. I will skim over the book again when next at Dad's (for it is not on my bookshelf, so ergo and QED, it's on his) and see if I can find it again.

For those of ya interested, I highly recommend Phil Kerr's book. Covers the McLaren team from the McLaren service station in Parnell in Auckland, NZ, to when Phil left McLaren for retirement several years after Ron took over. Excellent read.

[Schumikonen 2]

No, the diffuser should be much the same size accounting for suspension layout and chassis shape - they will just be generating more downforce. A Gurney Strip (or Flap as Mike likes to call it, which I believe is really a misnomer as it doesn't flap at all - unless it comes off of course) is generally just a piece of right angle aluminium or composite attached to the wing element, which as you can imagine will cause considerable drag, but in this case it is wanted drag, as it turns a wing, say 250mm wide, into one offering the same downforce as one, say 350-400mm wide, but of course you are not carrying the weight, nor needing to account for additional size of any aeropackaging.

Here is an example on a Swift DB4 Formula Atlantic, most noticeable on the front wing, though you can make one out on the lower wing foil, and the top foil has one that is painted yellow.

The technology involved in a Gurney Strip makes complete sense today, but when aero on cars was being worked out back in the 60's and 70's, it was quite a revelation. Often its the simplest ideas like this that turn out to be the best, same as the ducting of the air over the wing, which is actually counteracting the Gurney strip.

A lot of aero was sort of just "found out" by the drivers back in the day. For example in testing one of their M8's for Can Am, Bruce McLaren noticed that the he was handling better in testing after having come into the pits and been refuelled with the petrol flap not secured back in place...as he went down the straight he would watch this flap open up the faster he went, and in high speed corners this flap would stay up due to the wind pushing it up from underneath, giving him better front end handling. He stopped in at the pits, got out of the car, went to his toolbox (would you see a driver do THAT today??), pulled out a pair of tin snips, and attacked the bonnet on the car around the area of the petrol flap, opening up the hole. Everyone was kind of WTF (though they were a bit less gruff than that back in early 70's in England, it was more like, "Old Boy, what the blazes do you think one is doing there?") as Bruce jumped back in the car, and then went and set several lap times considerably quicker than he ever had before.

This is really interesting, with posts like this I don't need the Pre-race coverage

[Autumnpuma 0]

No, the diffuser should be much the same size accounting for suspension layout and chassis shape - they will just be generating more downforce. A Gurney Strip (or Flap as Mike likes to call it, which I believe is really a misnomer as it doesn't flap at all - unless it comes off of course) is generally just a piece of right angle aluminium or composite attached to the wing element, which as you can imagine will cause considerable drag, but in this case it is wanted drag, as it turns a wing, say 250mm wide, into one offering the same downforce as one, say 350-400mm wide, but of course you are not carrying the weight, nor needing to account for additional size of any aeropackaging.

How tedious. It's commonly called a 'flap' whether it's actually a flap or not and it's commonly called a 'Gurney Flap' in many publications. I've also heard it called a 'Gurney Strip' as well. Here are some publications that use the term Gurney Flap:

Journal of Aircraft, Enhanced aerofoil performance using small trailing-edge flaps

Motorsport Magazine

A water tunnel study of Gurney flaps; NASA

Those are just a few.

Also, it doesn't cause a lot of drag..that's the beauty of it...massive downforce with very little drag.

The technology involved in a Gurney Strip makes complete sense today, but when aero on cars was being worked out back in the 60's and 70's, it was quite a revelation. Often its the simplest ideas like this that turn out to be the best, same as the ducting of the air over the wing, which is actually counteracting the Gurney strip.

A lot of aero was sort of just "found out" by the drivers back in the day. For example in testing one of their M8's for Can Am, Bruce McLaren noticed that the he was handling better in testing after having come into the pits and been refuelled with the petrol flap not secured back in place...as he went down the straight he would watch this flap open up the faster he went, and in high speed corners this flap would stay up due to the wind pushing it up from underneath, giving him better front end handling. He stopped in at the pits, got out of the car, went to his toolbox (would you see a driver do THAT today??), pulled out a pair of tin snips, and attacked the bonnet on the car around the area of the petrol flap, opening up the hole. Everyone was kind of WTF (though they were a bit less gruff than that back in early 70's in England, it was more like, "Old Boy, what the blazes do you think one is doing there?") as Bruce jumped back in the car, and then went and set several lap times considerably quicker than he ever had before.

Please link a source or publication I can check out that says Bruce McLaren was the inventor of the strip on a rear wing. I can find many references to Gurney being the first to try it on a rear wing but nothing about Bruce McLaren. I can find vague references to studies being done in the 50s, but not on the trailing edge of an airfoil.

[HandyNZL 1]

Yeah, I was flicking through Phil Kerr's book last night (though I was half asleep doing it). Dan and Bruce were great mates, as you most likely know, with Dan quite often racing for McLaren. I'm 80% certain I read it in this book (To Finish First), but it may be in McLaren Memories, which is a recent one that Eoin Young has written. I've definitely read it in the last three years, just got to find the book and passage (which means I may need to read the books cover to cover again).

Flap, strip, potatoe, potatoe. We call it strip down here in the colonial outposts of Her Majesties Empire. Birds flap.

And I was meaning downforce rather than drag - sorry if you misinterpreted my misinterpretation of the interpreted interpretation I think Schumikoninbunny understood. I believe I clarified it where I said "It will be generating more downforce" Next time I shall be much more tedious

[Persevere 0]

Yes, I've also started the process of skimming through some books that may help to 'flesh this out' a bit. Terminology: back in the late 1980's/early 1990's I would often hear U.S. television announcers use the term wickerbill interchangably with Gurney Flap and Gurney Strip. Which reminds be of an exotic dancer I once knew...

Does anyone remember the fellow who tried to run a wing on his Porsche at Le Mans in the mid-1950's? Somehow the name Michael May comes to mind, but my mind is not what it used to be.

[HandyNZL 1]

Used to race mountain bikes against a guy called Michael May....he was a bit young though to have been driving a car in the '50's though.

[HandyNZL 1]

The reason the anecdote has stuck in my mind is that I always assumed Dan invented the strip/wickerbill/flap/bit of aluminium since his name was attributed to it, but reading the passage made me go, "oh, interesting"...and subsequently filed the information in the mildly interesting factoid pigeon hole in my brain

[Schumikonen 2]

Ok, now that your are into this technical aspect of F1 I have a question about a recent event in the Canada GP.

In that race Vettel was suffering from an gear box failure or problem, he complained about that over the radio and the team answered they were looking at it, later the team told Vettel that they took care, fixed or resolved the problem I don't rememeber exactly the words used by them, as far as I know there was nothing the team could do to fix any problem like this without stopping the car, I know there was a time with a two way communication between the car and the team but that was changed and the car were only allowed to send data and not to receive any, if that is still the case the team could not have send any signal to the car to "fix" anything and because of this my question is:

What really happened in this case?

my guess is that it was a temporary problem that just dissapeared and because of that they told him that everything was taken care of but he remained with some kind of problem until the end because when he asked about the fastest lap of the race his engineer almost die and told him "don't even think about we have enough problems, you are just what we need, good job" again the words may be different but that was the idea.

[Autumnpuma 0]

I'm putting those two books on my 'to buy' list! Thanks!

The aerodynamic theory behind the Gurney flap was probably being researched long before Bruce McLaren or Dan Gurney decided to use bits on their race cars. What I'm talking about is the specific application of a small flap perpendicular to the horizontal plane of an airfoil as first used on a race car by Dan Gurney in 1971. McLaren might have been using the same principle on a different area of his cars, and Dan remembered that, but that's not relevant to the Red Bull's diffuser...which is the point of this thread.

Also, while I appreciate the extra technical details, my intention was to explain a bit of current F1 aero without such details. I had hoped to explain this in a way that everyone could understand, regardless of their technical knowledge.

On drag, iirc there are two different kinds of drag, only one beneficial to a racing car. Pardon me if I get the terminologies wrong; I'm typing this without any reference in front of me. If you take a brick and shoot it at high speed, you would get the air hitting the flat front and deflecting off of it, slowing the brick down. That's one kind of drag sometimes called deflection drag, or resistance drag. You get this when you angle a wing almost vertical...the air hits it and deflects upwards, pushing the wing down and as a result, pushing the car's mass down on the tyres. Grip through a beneficial kind of drag and heavily used at slow-speed tracks such as Monaco.

The second sort of drag is what happens at the rear of that speeding brick. As the air flows over the brick, it tends to exit and create a low pressure area just behind the flat back of the brick, creating a vacuum-like force that pulls on the brick, slowing it down. This is the sort of drag that race cars try to avoid. The whole idea of an airfoil shape is to minimize that flat back.....to smooth the air behind an object (or car). Interestingly, if you put a Gurney flap on the back of a brick, you get a small amount of resistance drag but you almost completely remove the drag behind the brick.

[HandyNZL 1]

Same application with winglets on Boeings and Airbuses....tidies up the air coming from under the wing, prevents the wing from vibrating outside the limits of the design, and in all making the wing more slippery, and thus the hole plane more fuel efficient.

Regarding Vettels gearbox....ummmm.....me have um big thunk on that....

[Autumnpuma 0]

Ill look into the gearbox thing as well. As unscientific as it sounds, sometimes gearboxes fix themselves during a race...

[Autumnpuma 0]

Same application with winglets on Boeings and Airbuses....tidies up the air coming from under the wing, prevents the wing from vibrating outside the limits of the design, and in all making the wing more slippery, and thus the hole plane more fuel efficient.

Regarding Vettels gearbox....ummmm.....me have um big thunk on that....

Yup. There are little vortices (swirling bits) of air that come off of the ends of a plane's wings that cause drag. Those winglets eliminate the vortices and eliminate most of that drag. The little winglets and flip-ups on an F1 car's front wing do a similar job (i.e. to clean up those vortices).

[asj 0]

... it was LeMans, in the 1960s. Pete Brock's Cobra Daytona, drivers getting front end lift, down the Mulsanne. Dan grabbed an engineer, took him for a spin. Engineers relieved the hood on the Daytona, with venturies, to circulate dirty coming through the radiator, out the top of the hood. Top edges of those venturies, you'll see "flaps." FYI: 1971, Dan Gurney had already retired-- QED, asj.

[Medilloni 6]

This thread's been bugging me, can't find much info on the 'net, and my memory isn't that good!

Who invented it? My first job was at around the same time Gurney flaps/strips became a must-have ('69/'70), and I remember the designer/owner (Derek Bennett) of the company talking about the theory of them to us all, and stories about how the hell we could get rid of the terrible understeer they caused on high speed circuits, because they are so effective - a problem that everyone had when they first used them. The answer to this was initially the front 'lip' made from yet another strip of aluminium bolted so that it stuck out of the front of the bodywork, which then of course grew into a more wing-profiled nose or a nose wing.

His story was that Dan Gurney was the first to make one and put it on a car, though Dan was inspired by Ritchie Ginther's work on the Ferrari's of that time - apparently Ginther was a massively gifted driver in terms of development and was trusted by Ferrari to bolt on bits of bent aluminium as he saw fit.

Still, this is working from memory, so is as good as hearsay!

Lots of stories came out around that time about (in a sportscar) high and low pressure areas that the driver described to the team - how the bodywork was lifting or being sucked lower - in some cases by air getting under the nose and into the front part of the spaceframe/monocoque, or not getting in and causing a vacuum which sucked the bodywork in; the first seeds of ground effect I think?

Flaps or strips? We (and other team members we met) called them 'flaps' on short width wings (our Chevron B16, similar to the Porsche 908/02), 'strips' for full width (rear wing of a formula car or wing proflile the full width of the rear of the sportscar). This I do remember; all apprentices were instructed to get their spanking new scribers out, measure up bits of ally to fit all the wings and bodywork of each of the cars, then spend days on a manual folding machine bending loads of them into pretty right angles. You can call me Bender

Another question for y'all

For such an incredibly simple, and great idea, Dan Gurney's name is on an idea/concept directly from motorsport.

So, who else has achieved the same?

[Senna's Ghost 0]

What a fantastic thread this has become. Great to hear from those around at the time with their memories of working on the cars of yesteryear. Absolutely fascinating.

I have nothing to add to the thread but I am very interested in hearing more from you all. Keep it up.

Tchau.

[Autumnpuma 0]

Thanks Meds and asj. Fine posts there Alas, I have no answer for you Meds.

Here's some additional information on Red Bull's blown diffuser. One problem with blowing exhaust gasses is that when you lift off the throttle, your downforce goes away. Red Bull are possibly using a..wait for it....retarded ignition system. Okay, I'm playing with the words there for a cheap laugh, but it's true. In a normal cylinder, as we all know, combustion takes place inside the closed cylinder which opens for the exhaust to travel out. Red Bull are igniting their air/fuel with the exhaust valve open. What this does is create a steady stream of gas traveling through the exhaust and over/under their diffuser regardless of throttle position. Viola! Constant downforce.

This isn't a new concept but it's certainly not being used by anyone else yet. As with any good thing, there is a negative side to it. It burns more fuel and it generates much more heat in that whole area (perhaps not a faulty spark plug after all?).

Too bad Andres, Graham or Adam haven't dropped by to add their two cents worth. Though everyone who's posted in here so far has done a fantastic job!)

[HandyNZL 1]

Jonathan Leggard is trying his bestest to have the word Schumacheresque be used to describe someone going fast....just imagine:

Man pulled over by policeman

"Excuse me so, do you realise how Schumacheresque you were traveling back there?"

"Ah, no Sir...how Schumacheresque was I going?"

"About $400 worth Sir"

"I'm really sorry, but my Schumacheresque gauge must be faulty...."

"You should really have that checked out then, Sir. Too much Schumacheresque can be quite a dangerous thing."

"Yes Sir...I'll watch out for going Schumacheresque in the future Sir"

"Very well Sir. Have a nice day"