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Aren't they suppose to be vortex generators? To generate vortexes on the side of the car, now allowing air to get underneath
Somewhat, yes.
They create a minor direct downforce effect acting on the uplift angle.
They create a sealing vortex alongside the car to aid in keeping high pressure out.
They create a lower pressure in front of the tire which helps air flow faster under the splitter.
It's all in placement and design though.
Two things I see wrong with Patrick's as per the car picture he posted.
1) the initial angle of attack (leading edge) should be parallel to the ground which is the direction of oncoming air.....so they should be flat for a percentage of their length before turning upwards.
2) Patrick’s seem to be too highly placed to have a low pressure effect on the splitter and the angle is so extreme that they would allow detachment and turn them into turbulence generators.
It's possible the side plates on Patrick's compensated for spillage and detachment due to incorrect initial angle and steep uplift....but if they did, the directed air is aimed right at his rear wing which may have increased REAR downforce, not lessened frontal.
It's possible too, knowing the side curtain effect as one feature of a proper canard, that the original guy who recommended he delete them, took into account the unconventional side profile of his car with the offset wider front fender as compared to the door....?
I'm not an expert, just a student and a fan of McBeath's book.
It'd be interesting to know if Patrick actually fwd pics of his setup and what Simon's comments were, or even whether when the "lifting" pics or video were current, was there data that showed increased REAR squat and/or downforce.
T
Last edited by 951and944S; 07-15-2017 at 12:46 PM.
In that thread, I asked about diffuser angle changes but never got a reply.
It seems logical to me that if car behaved best at lowest angle setting, it would make sense to experiment by making at least one more shallower angle adjustment possible, otherwise you'd never know with best setting found against a stop.
In other words, you have to have ability to go too far, past optimal setting to know it is best.
Best of what you have, yes, but not maybe best that' possible.
It's accepted that 7-10 degrees should be optimal in retaining attachment of air flow but there are too many car-car variables for this to be set in stone...i.e. smoothness of floor, concave vs. convex shape, etc.
To the original poster, please accept my apologies for side tracking. This is a subject that interests me & I will be installing canards to my 944 turbo also.
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Patrick, as you should know I am a fan of your work. Your project is incredible.
I recall your comment about lifting in the front end and it's something I have struggled with on gravel (not pavement). I wanted to ask you about weight distribution. I know your suspension is incredibly stiff (high spring rate) compared to a stocker.
I had an idea I wanted to pass by you: put more weight on the front end of your car, shift some weight forward.
Look past the 911 and zoom in to the brz type car. Presently I have this "external dam/splitter/canard" design at the forefront of my mind for my inter-cooler'd street car.
Alternatively, for a car that was set on "bringing it" to the track... Why couldn't a car bolt on something like this? I have thought something like this would match Patrick's dual plane wing nicely. But for any car... just bolt it on at the track and have super down force at the front axle. no? This is also on the menu for my car in future, for consideration.
I'm a tech by trade, 35 years and really into F1 so all of the aero stuff always interested me.
Years ago.....15 years probably, and I date this by a just finished 944S when my son was 16 that's in the 3rd pic...., he's 29 now, I built a custom front splitter, laid by hand from a GT Racing core based on the 993 RSR for a part time track/street 944T I owned.
Had set back center and hand shaped end plates in an attempt to dam spillage off the ends and direct along the lower factory 944T add on rockers. The center width matched an add on that tied to my factory undertray along with the secondary 944T rear under metal piece.
10-12 years ago, I hand built an 11.25 degree rear diffuser of my own design out of hand laid fiberglass that mounted to a custom bracket on a 968 six speed and the factory tow bracket studs and was molded to fit my vented and notched rear bumper. The outer two sections were exhaust blown with a Burns stainless 1 into 2 exhaust splitter to excite air flow enough to pull turbulent waste air from rear wheel wells.
Just trying to display that I'm not a 15 year old copy and pasting BS from around the net.
Been there done that.
For longer than most people ever owned a 944.
I'd show y'all the under floor of my current project but you'd have to apply for security clearance through a Russian lawyer friend of mine first.....
Even though we bash heads sometimes I respect and admire you.
Am enjoying your comments. Big time.
Aero stuff is fantastic.
"black art" like you say.
If "bashing" is me wishing you to succeed by trying to make you avoid mistakes that I either made or thought through to avoid...., then I'll keep bashing....
Don't disagree with what you're saying Mr T. Our first effort was homespun and rather rushed. The point I was making about Mr McBeath was that in a nutshell, he said that they can create more drag than downforce. Quite likely what we had initially.
Re the link to Disasterman's car, I was just pointing to some diveplanes if someone were interested.
Were you able to quantify results with the rear diffuser?
Don't disagree with what you're saying Mr T. Our first effort was homespun and rather rushed. The point I was making about Mr McBeath was that in a nutshell, he said that they can create more drag than downforce. Quite likely what we had initially.
Re the link to Disasterman's car, I was just pointing to some diveplanes if someone were interested.
Were you able to quantify results with the rear diffuser?
No..., no I wasn't able to. I got tied up working on an inclined flat rear wing with adjustable center that I thought would be a better companion to the diffuser then turned course and home made a hot wire foam cutter to cut my own rear wing laid up by 2 oz weave and epoxy resin with my own design tigged aluminum uprights.
This was an all out PCA GT car (close to equal to your "open" class) with a 3.0 liter turbo 968 engine with 6 speed, standalone, etc. (parts from this shelved project are for sale at Pelican in a thread by my RL user name - more to come too)
10-15 years ago, you could count 3.0 16V turbos on one hand.
Right about wing/diffuser fab, PCA changed class rules for engine based on a power/liter formula that made the project obsolete, so I traded an orthodontist friend of mine, the engine with the 968 pistons for an NA implant to a 944 body car he had in exchange for $6500 worth of braces for my daughter's teeth....
LOL, for about a year, I'd stop and put my ear to my daughter's mouth until one day my wife asked...."what are you doing...?"
Me - "I'm trying to see if I can hear my engine run in there"
The guy blew the engine around the carousel at Road America and gave me the engine back free of charge. Hole in the block but I sold off some of the good stuff. Dave Mcgrath got the cylinder head, can't remember the rest.
I felt so bad for the ortho, I rebuilt a 323i automatic transmission for him for free.
I still have that diffuser though. May use it one day but current car I am building does not allow diffusers for class.
Doing a 7500-8000 rpm 2.5 16V S engine right now.
Waiting on the piston drawing spec sheet from Chris White to sign off on and Performance Developments is getting my crank next week.
If I can get CatCams to answer an email, I'm golden. Taylor at PD said they could design an optimized cam set for me but I already worked out what I want. "level of competitiveness" is how they put it.
I have a secret weapon though in place of all out money investment that most have to invest in parts to be "competitive".....my son could drive a wooden wagon $hitbox to 1st place.
I do my thing, my son drives. Other than an occasional multi driver enduro or local heat race or two I gave up driving when I realized that I can't beat him....
Here's an old pic of the experimental wing. Body attachment to the non moveable side sections was the real hurdle that made me toss idea and move to upright style wing.
The diffuser looks larger and lower in the pic than it actually is, larger because a few inches of it's height notches into the lower factory bumper and bolts there and lower because the car is raised on stands in the front.
If this paint scheme looks familiar, the lime green NA SP2 car my son drives that I post from time to time to the cue from this car which was the original sibling.
It makes sense that canards are used for tuning rather than big down force. I guess you can always ask yourself "how substantial is the mounting hardware?" This will help rate where the device fits in the downforce field.
Is there a theory of why 2 or 3 stacked canards vs singles?
1.
an unfounded rumor or story.
"the old canard that LA is a cultural wasteland"
2.
a small winglike projection attached to an aircraft forward of the main wing to provide extra stability or control, sometimes replacing the tail.
07-15-2017, 12:25 PM
