GT Mk1 aerodynamics
- Thread starter mlevea
- Start date
Howard Jones
Supporter
Really I guess a lot of the discussion around here about these cars is bench rac'in but I would like to know that I have built my car to be safe If I really push it. Will I ever get mine above 140 or so? Its not very likely on the street is it. Safe surely not, but do we all like to fiddle with our cars as if tomorrow we will starting at lemans , Ya you bet! Part of the hobbie I guess. And who knows maybe I'll get the call someday. You know some rich guy with lots of money and no braines that wants to take a trip to France.
Has anyone tried to actually retro fit a nose splitter? I am sure it would be very easy to make one. Just need a good design, and by the look of the new GT, it need not be too intrusive, nor spoil the look of the orginal design of the 40.
So anyone know a good spoiler designer?
Regards,
J.P
So anyone know a good spoiler designer?
Regards,
J.P
JP,
John Tiemann has designed, and will be fitting
a splitter, sill extensions, and undertray(diffuser)
to his DRB in the near future.
Hopefully, he will share his experience on the Forum.
Bill
John Tiemann has designed, and will be fitting
a splitter, sill extensions, and undertray(diffuser)
to his DRB in the near future.
Hopefully, he will share his experience on the Forum.
Bill
I talked to the Ford aero guy at Monterey concerning the Ford GT design. They basically made over a dozen spliters and a dozen diffusers and tried them on the car in the wind tunnel and on road to find out the effects. On road data logging of suspension ride height over a known piece of smooth track is a valid method of determining gross effects. Down force will cause the suspension to deflect and measuredm. The deflection can be easily calibrated with dead weight applied over the front axle and rear axle independently.
David Morton
Lifetime Supporter
We are talking about a car that was designed in the 1960's.
When I look at the current crop of LeMans winning cars such as the Audi R8, the Bentley Speed 8, and the McLaren GTR F1 they all have one thing in common. They have virtually no ground clearance and the ride height is minimal. Each of these cars have 'scalloped' diffusers under the rear body work( the Mac had two strakes just inside the limits of the rear wheel with a flat undertray, The Mac/ Williams had a low pressure 6 strake set up and the R8 had a low P area with two rectangular continuations of the undertray.
To achieve anything near the levels of downforce these cars have would need a major redesign of the GT40 bodywork with considerable lowering in ride as well. I wonder why ford are not redesigning it ? Probably because the gt harks back and thats what they want to do - to recapture the babyboomers some of who now have some spare money.
Canards and Gurney flaps go a part way to addressing the aerodynamics but while whe have a (beautiful) front end
instead of a slab air damming wall and we have relatively large radiator inlets,we are faced with copious amounts of air underneath the car. If your GT40 is only for the track and you have a truck with a tail lift to move it around, and you have a good understanding of aerodynamics any road going car is best left alone. All of the major race companies employ the cream of the crop to design their aero's with all sorts of tools to do the job. Unless we have one in our midst on the forum, you could be biting off much more than you could ever chew. (IMHO)
Dave M
When I look at the current crop of LeMans winning cars such as the Audi R8, the Bentley Speed 8, and the McLaren GTR F1 they all have one thing in common. They have virtually no ground clearance and the ride height is minimal. Each of these cars have 'scalloped' diffusers under the rear body work( the Mac had two strakes just inside the limits of the rear wheel with a flat undertray, The Mac/ Williams had a low pressure 6 strake set up and the R8 had a low P area with two rectangular continuations of the undertray.
To achieve anything near the levels of downforce these cars have would need a major redesign of the GT40 bodywork with considerable lowering in ride as well. I wonder why ford are not redesigning it ? Probably because the gt harks back and thats what they want to do - to recapture the babyboomers some of who now have some spare money.
Canards and Gurney flaps go a part way to addressing the aerodynamics but while whe have a (beautiful) front end
instead of a slab air damming wall and we have relatively large radiator inlets,we are faced with copious amounts of air underneath the car. If your GT40 is only for the track and you have a truck with a tail lift to move it around, and you have a good understanding of aerodynamics any road going car is best left alone. All of the major race companies employ the cream of the crop to design their aero's with all sorts of tools to do the job. Unless we have one in our midst on the forum, you could be biting off much more than you could ever chew. (IMHO)
Dave M
David,
I don't think most folks here are talking about the massive undertaking you are talking about. I believe this issue is to address high speed stability with minor, un-obtrusive aids like a small chin splitter, as per the new GT, and maybe a Gurney, as per Howard's GTD. BUT IMPORTANTLY - without changing the appearance of the origanal design.
I don't think that any of us will be entering Le Mans(I wish!!) and require the need for enourmous amounts of downforce and ground effect etc.
Put it another way. If someone approached me and said " Hey, J.P I've got a chin splitter you can fit to the front of your 40, it'll only effect your ride hide by about 1 inch. But it will provide a noticeable increase in stability at 160mph. And costs $250!". I'd rip his bloody arm off and fit it immediately.
Regards,
J.P
I don't think most folks here are talking about the massive undertaking you are talking about. I believe this issue is to address high speed stability with minor, un-obtrusive aids like a small chin splitter, as per the new GT, and maybe a Gurney, as per Howard's GTD. BUT IMPORTANTLY - without changing the appearance of the origanal design.
I don't think that any of us will be entering Le Mans(I wish!!) and require the need for enourmous amounts of downforce and ground effect etc.
Put it another way. If someone approached me and said " Hey, J.P I've got a chin splitter you can fit to the front of your 40, it'll only effect your ride hide by about 1 inch. But it will provide a noticeable increase in stability at 160mph. And costs $250!". I'd rip his bloody arm off and fit it immediately.
Regards,
J.P
David Morton
Lifetime Supporter
JP,You are absolutely correct and if it were a functioning unobtrusive well thought out part, then I would be in the queue behind you. I only put an extreme view which I see, manifested in the cars of the teams I work with, tempered with the fact for me its difficult to get one of these cars (a gtd40) on and off a trailer without further protruding extensions. In fact, all the body work (on the LM cars I see) is carried seperately and is only fitted in the pit garage.
I look forward to seeing one of Ford GTs in the flesh and my camera will be working overtime. One thing I note is the small lip above the center removable panel (bonnet/hood) is not there. Would this be an attempt to perhaps alter the (whole car) centre of pressure? Any chin 'Splitter' will have an effect but how have Ford converted the previous -ve lift into +ve. Is there some sort of ram decceleration (box) structure under the car?
All of these things I would love to find out but at the end of the day, the -40 still has to be the most beautiful shape ever.
Dave M
I look forward to seeing one of Ford GTs in the flesh and my camera will be working overtime. One thing I note is the small lip above the center removable panel (bonnet/hood) is not there. Would this be an attempt to perhaps alter the (whole car) centre of pressure? Any chin 'Splitter' will have an effect but how have Ford converted the previous -ve lift into +ve. Is there some sort of ram decceleration (box) structure under the car?
All of these things I would love to find out but at the end of the day, the -40 still has to be the most beautiful shape ever.
Dave M
I agree with JP. There is quite a large spectrum of effort and cost between doing nothing to a current GT40 and designing a competitive LM car. I think there is a happy medium in between which I am confident we can do for example. I do work amongst some of the most talented aero guys in the US.
The modifications which Ford has done to the GT are relatively straight forward and do not significantly effect the ground clearance, etc. It is not like they put a huge effort either as a few engineers did the entire aero design in ~12 months. The main drawback on our part is the lack of significant budget to permit wind tunnel testing. As this is more effective then on vehicle tests, etc.
The modifications which Ford has done to the GT are relatively straight forward and do not significantly effect the ground clearance, etc. It is not like they put a huge effort either as a few engineers did the entire aero design in ~12 months. The main drawback on our part is the lack of significant budget to permit wind tunnel testing. As this is more effective then on vehicle tests, etc.
David Morton
Lifetime Supporter
Gary,
I think computational fluid dynamics have become 'de rigeur' in any design house, but I think you underestimate how much effort was put into the new Ford car. Further more,(IMHO) Ford could not cope with the adverse publicity if one of their GTs (whilst trying to run at any venue) flipped, much like Mercedes did in 1999 at LM, hence they have done their homework big time before this one was released.
Look at how much adverse publicity any vehicle recall creates (how many recalls has the Explorer had to date - probably 7 or 8). I digress. Ask any of the talented aero guys you work amongst about the difference between something that seemingly works in a low speed tunnel but not on the road or in the air, and vice versa.
It's an amazing tool to use but only in the hands of a very skilled technician. Wouldn't it be nice if we had one on the forum (a technician)? What I am trying to say, not very succinctly, is that there is a very fine line between a Spoiler/flap/canard/bargeboard/wing and the car you intend to use it on and its effects on that particular car [show me two GT40s that are set up the same ie Height/springs/ bump/ rebound]. Anything we produce ourselves will, generally, only be analyzed subjectively, and probably 'talked up' by the person/s who made it.
But all that doesn't stop any of us trying - because I think the particular sort of person that attempts to build one of these cars is not the usual run of the mill joe soap, and if something is going to be a challenge, then it's all the more rewarding when its done.
Time for the pub
cheers
Dave M /ubbthreads/images/graemlins/smile.gif
I think computational fluid dynamics have become 'de rigeur' in any design house, but I think you underestimate how much effort was put into the new Ford car. Further more,(IMHO) Ford could not cope with the adverse publicity if one of their GTs (whilst trying to run at any venue) flipped, much like Mercedes did in 1999 at LM, hence they have done their homework big time before this one was released.
Look at how much adverse publicity any vehicle recall creates (how many recalls has the Explorer had to date - probably 7 or 8). I digress. Ask any of the talented aero guys you work amongst about the difference between something that seemingly works in a low speed tunnel but not on the road or in the air, and vice versa.
It's an amazing tool to use but only in the hands of a very skilled technician. Wouldn't it be nice if we had one on the forum (a technician)? What I am trying to say, not very succinctly, is that there is a very fine line between a Spoiler/flap/canard/bargeboard/wing and the car you intend to use it on and its effects on that particular car [show me two GT40s that are set up the same ie Height/springs/ bump/ rebound]. Anything we produce ourselves will, generally, only be analyzed subjectively, and probably 'talked up' by the person/s who made it.
But all that doesn't stop any of us trying - because I think the particular sort of person that attempts to build one of these cars is not the usual run of the mill joe soap, and if something is going to be a challenge, then it's all the more rewarding when its done.
Time for the pub
cheers
Dave M /ubbthreads/images/graemlins/smile.gif
David I agree. Most LM cars are heavy ground effect cars and thus their proxcimity to the ground is very important. This is one of the reasons for the MB problems at Le Mans. CFD is still hard to apply 100% epecially for an entire car in ground effect (The CFL3D "CFD" code that is widely used in aircraft design was written about 100 yards from my office). There is however a lot that can be learned and applied on a case by case basis with lots of testing, etc. You can readily instrument a car with data logging equipment and tell what kind of lift or down force the car has to a couple of significant digits. That is the kind of stuff I am going to look at. I will leave the hard core CFD /wind tunnel testing to those with lots of time and money /ubbthreads/images/graemlins/smile.gif Unless I can convince the guys to model a car instead of an aircraft.
Cheers.
Gary
Cheers.
Gary
...and then you get in the dirty air behind another car and throw all your wind tunnel tests out the window /ubbthreads/images/graemlins/shocked.gif
Peter Delaney
GT40s Supporter
Interesting - the late great Zora Arkus Duntov (GM's Corvette guru) twigged to the lift problem back in '68. The initial protos of the new '68 "shark" Vette exhibited alarming V1/V2 tendencies. The addition of a small chin spoiler & the reduction of the built-in rear spoiler combined to balance things out so that the car was quite stable at Zora's target speed of 140mph.
The '40 does not seem to have the excessive downforce problem at the rear (like the proto Vette), but could benefit fron a small chin spoiler to reduce front-end lift - perhaps it could be just an inch high, & mounted slightly forward of the lowest part of the front edge of the clip so that ground clearance was not affected too much. If done in matt black, it would be almost invisible (like the old Vette & the new Ford GT).
Kind Regards,
Peter D. /ubbthreads/images/graemlins/smile.gif
The '40 does not seem to have the excessive downforce problem at the rear (like the proto Vette), but could benefit fron a small chin spoiler to reduce front-end lift - perhaps it could be just an inch high, & mounted slightly forward of the lowest part of the front edge of the clip so that ground clearance was not affected too much. If done in matt black, it would be almost invisible (like the old Vette & the new Ford GT).
Kind Regards,
Peter D. /ubbthreads/images/graemlins/smile.gif
A front chin spoiler would help things, but most manufactures (ST, new GT, etc.) have gone to the spilter as it can provide more downforce without extending in down at all (just out front).
This website http://www.mulsannescorner.com/ has some cool info on areodynamics, its main focus is on le mans cars, but it has some good explenations for people like me, for whom areodynamics is a black art!!
David Morton
Lifetime Supporter
The Saturday Telegraph (Motoring Telegraph) here in the UK has a reasonably good article about the Bentley Speed 8 being driven by a journo at Ricard, but on page 3 there is an article entitled "Down force - the Dark Art".
Quite a good read for the small room.
Dave M.
Quite a good read for the small room.
Dave M.
The top-speed test of the RF40 (mentioned in another thread at 282 km/h) suggests that the concern about high speed instability of the MK1b body is not at all bad as implied in this thread. Keeping in mind that the original MK1 body had an upturned nose and no rear spoiler, the Mk1b was a great improvement on it. After reading this thread, I asked myself how 150lb of lift can effect stability when there are still 500lb or so of gravitational force still working in the opposite direction. Certainly it will effect grip, but that's a long way from instability. Just my thoughts /ubbthreads/images/graemlins/smile.gif
Chris,
If that 150 lbs of lift brings the nose up so your front ride height is higher than the rear I'm sure you'll notice that in the stability of the car.
To let you all know I am designing a splitter for the GT40 and I'm planning to sell it through my XtremeClassics venue.
An off topic note: The first set of Xtreme GT40 headers are being built as I write this. Should have them to show within a month.
Mark
If that 150 lbs of lift brings the nose up so your front ride height is higher than the rear I'm sure you'll notice that in the stability of the car.
To let you all know I am designing a splitter for the GT40 and I'm planning to sell it through my XtremeClassics venue.
An off topic note: The first set of Xtreme GT40 headers are being built as I write this. Should have them to show within a month.
Mark
Mark,
When will you have the splitter off the drawing board
and begin to manufacture them?
Bill
When will you have the splitter off the drawing board
and begin to manufacture them?
Bill
Doing high speeds in a GT40 sounds like a no brainer but I have to say that it requires a lot more than one thinks for a GT to go past 150MPH. While at Run and Gun the highest speed I could attain was about 133 MPH in the striaght away. That's because of the driver, not the car. However, I have had the car to 153MPH and that was my limit. Mainly because the GT felt light to the front and I honestly felt that any faster would cause the thing to fly. Any car that attempts to go past that speed will have to be setup to go beyond 150MPH. It's not a matter of power so much as it is about aerodynamics. If you try to go that fast without proper suspension setting and proper aerodynamics then you're in for a surprise. There is no doubt the GT can acheive 200MPH speeds with the right chin spoiler and suspension changes. Just not with me in it. /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif
Hersh /ubbthreads/images/graemlins/smile.gif
Hersh /ubbthreads/images/graemlins/smile.gif
