Rick Starkweather
Well-known member
Don:
Can't make Grattan. Work conflict that weekend. Any chance you'll make it to the Gold Cup?
Rick
Can't make Grattan. Work conflict that weekend. Any chance you'll make it to the Gold Cup?
Rick
Aero Questions, Especially for MGB racers
- Thread starter dcharnet
- Start date
JohnMcNaughton
Well-known member
The use of front and rear under trays, radiator and hood vents, along with behind the tire fender vents, are all interconnected. Together they provide a systematic reduction of under body LIFT, venting air upwards to a lower pressure area over the front or out the rear of the body. Given that they are very common in ALMS and Grand Am, they must be productive. And their dimensions are specified, in some cases, and open in others. The aero devices and affects, as used in ALMS and Grand Am, are more effective above 90-100 mph. And most effective above 135 mph. Slower than those speeds and the lack of aero affect puts the prototypes on an equal footing with the stock bodied cars they are trying to pass in the slower corners. At that point, it is all about mechanical grip, not areo advantages.
Prod rules are specific, only as original body work. If you are trying to run under "non-prod rules" then it may be worthwhile to add the venting and ducting. Laminar air flow at the leading 1/4 surface of an MGB hood, with flat fronted grill, is negligible. That area will have reduced air pressure over it. Sealing the air gap between the bottom of the radiator and engine crossmember will help, if the air is then vented upwards thru ductwork in the hood to the upper body work. For the radiator vent up to the top of the hood, most venting starts a few inches from the bottom of the radiator and and angles to the rear of the car, til it contacts the hood. It should be sealed fron the radiator on both sides and the rear wall of the ducting. If you have any overheating with this, you may need to add a small vertical spoiler lip at the leading edge of the vent on the surface of the hood.
How much of your lap time is spent above the effective speeds required for the work invested into the ducting?
Aero work is a lot like air flow thru the engine. If you install a big lumpy cam without the improved carburation, headwork, and exhaust improvements, you will never see the full potential. And you may make it slower.
Prod rules are specific, only as original body work. If you are trying to run under "non-prod rules" then it may be worthwhile to add the venting and ducting. Laminar air flow at the leading 1/4 surface of an MGB hood, with flat fronted grill, is negligible. That area will have reduced air pressure over it. Sealing the air gap between the bottom of the radiator and engine crossmember will help, if the air is then vented upwards thru ductwork in the hood to the upper body work. For the radiator vent up to the top of the hood, most venting starts a few inches from the bottom of the radiator and and angles to the rear of the car, til it contacts the hood. It should be sealed fron the radiator on both sides and the rear wall of the ducting. If you have any overheating with this, you may need to add a small vertical spoiler lip at the leading edge of the vent on the surface of the hood.
How much of your lap time is spent above the effective speeds required for the work invested into the ducting?
Aero work is a lot like air flow thru the engine. If you install a big lumpy cam without the improved carburation, headwork, and exhaust improvements, you will never see the full potential. And you may make it slower.
John:
The cam synergy metaphor is instructive and succinct. That and the legality issue are enough for me to stop thinking about this.
Except, that is, for a row or two of those traditional hood louvers placed vertically just behind the radiator and of equal width (laterally) to it. This has been in my psyche since I saw my first Morgan.
Will they do any harm? Will they do any good, other than pleasing me aesthetically?
Don
The cam synergy metaphor is instructive and succinct. That and the legality issue are enough for me to stop thinking about this.
Except, that is, for a row or two of those traditional hood louvers placed vertically just behind the radiator and of equal width (laterally) to it. This has been in my psyche since I saw my first Morgan.
Will they do any harm? Will they do any good, other than pleasing me aesthetically?
Don
Protech Racing
Well-known member
MY airplane flies @ 34mph.( http://pou.guide.free.fr/connaitre/gret ... ogren.html) For me, it all makes a difference.
The only unlimited rules racing that I have been doing is Chumpcar.
Venting the hood is a big plus so far, cooler rad temps, less under hood pressure. I also use a large splitter/dam mostly to get lots of air into the brake ducts. I added front dive plates/wheel air diverters and rear wheel diverters after looking at the Aero Honda stuff. I also had removed the rear valence some time prior. I have vortex generators on the 6 in windscreen, mostly because they worked so well on my plane.
All of my hoods are white.
I have cut the roof off and removed most of the interior parts for the air to interface with. Not for aero value but more for weight.
MY HP Rocco car goes about 4mph faster with about the same power.(Daytona)
The trans Am car that I did Data(2001,2) for made about 600#( 166mph Sebring) of rear down vector, costing 4-8mph. Wing with biggest Gurney flap. Remove the flap equaled 250-300#. and only 2-3mph. All of these value are determined by average ride height on the shock travel sensors.
These cars liked the wing/flap in T 17 and T 1. And T14- 15- 16. The driver needed the big flap to flat foot the T 14 section, 137mph @ the inside blue curb.
No under trays back then. The lower rear body took in a lot of air IMHO. I was not the aero engineer, just the data guy, coach.
We did not mess with the front splitter package, as it worked and the car turned .
The new TA cars pay a lot of attention to the air around the wheel wells and under the car along with the inside of the body.
The CD for some Volvo is listed as having the front tires being about 30% of the drag value. Seems like enough to start looking into.
The only unlimited rules racing that I have been doing is Chumpcar.
Venting the hood is a big plus so far, cooler rad temps, less under hood pressure. I also use a large splitter/dam mostly to get lots of air into the brake ducts. I added front dive plates/wheel air diverters and rear wheel diverters after looking at the Aero Honda stuff. I also had removed the rear valence some time prior. I have vortex generators on the 6 in windscreen, mostly because they worked so well on my plane.
All of my hoods are white.
I have cut the roof off and removed most of the interior parts for the air to interface with. Not for aero value but more for weight.
MY HP Rocco car goes about 4mph faster with about the same power.(Daytona)
The trans Am car that I did Data(2001,2) for made about 600#( 166mph Sebring) of rear down vector, costing 4-8mph. Wing with biggest Gurney flap. Remove the flap equaled 250-300#. and only 2-3mph. All of these value are determined by average ride height on the shock travel sensors.
These cars liked the wing/flap in T 17 and T 1. And T14- 15- 16. The driver needed the big flap to flat foot the T 14 section, 137mph @ the inside blue curb.
No under trays back then. The lower rear body took in a lot of air IMHO. I was not the aero engineer, just the data guy, coach.
We did not mess with the front splitter package, as it worked and the car turned .
The new TA cars pay a lot of attention to the air around the wheel wells and under the car along with the inside of the body.
The CD for some Volvo is listed as having the front tires being about 30% of the drag value. Seems like enough to start looking into.
JohnMcNaughton
Well-known member
Someone asked about reading material. I have been reading everything I could find, since they started working on the Cobra Daytona coupe and the internal aero drag on the Ford GT40. I was following their development at the same time. That was in the early to mid 60's. The internal drag reduction with the GT40 ducting was claimed to be equivilant to an increase of 60 HP! Pretty significant. The significant increase in speeds at Indy during the 70's & 80's was from huge front & rear wings, as big as garage doors. The cars for a while had a slower top end speed, but never slowed down much for the turns. The wings helped lap times, but really reduced top end speeds. Cornering speeds were way up. All they needed was 800+ horsepower to push the wings thru the air...
I have read many books, but none of them stand out to me as better than any of the others. It is just accumulated knowledge and spending time in GT1, TranAm and IMSA GTO. When I get a few minutes I will go back to the Mulsanne website listed in some comments above.
Data acquisition and the ability to interpret it and utilize it is critical. The ability to get air pressure readings in all areas leads to what is needed and where to put it. There are too many variances between cars to say one thing works on all of them. If I had a Morgan or MG TD, I would put louvers on the rear of the fenders to reduce parasitic/parachute drag and some lift. But, then there is sooo much turbulence behind the fenders on those cars, because the hood side louvers are venting and mixing with the low pressure area behind and outside the rear of the fenders. OOPS, did that negate the drag of the fender? It's all interconnected.
There are lots of subtle aero tricks that have been used to improve aero quality. The Trans Am & GTO cars once had the trailing edge of the front wheel opening, from about axle height and down, angling in towards the chassis frame rails. It did not drop straight down from the widest point of the fender, it tapered inwards. It reduced turbulence in the wheel well and assisted in venting air from under the front of the car. Rules ulitmately removed that option. They then started using carefully rolled lips at the bottom rear of the wheel opening to minimize turbulence in that area. Can you reduce the lower trailing aero exposure of your front or rear fenders in that area? Can you seal off behind the tire, and under your fenders? It acts much like a drag chute in that dark area, behind the tire and in front of the door, building pressure/drag as you go faster. If you can't use vents in that area, seal it off to reduce the drag build up. A simple piece of flat aluminum is all that is needed. You want air over or around the car, not under it or in the large body cavities.
Within the Prod car rules makers there is an undercurrent to minimze advancing aero tech advances. They actually had to write into the rules the use of a front spoiler. It is difficult to work into the rules a simple flat panel rear spoiler, such as NASCAR uses. It is inexpensive and effective. But, it will not benefit the front wheel drive sedans in the classes. But it would really help my tail happy RX7 in high speed sweeping turns like T9 at Roebling Road. The 240Z and Spitfire would also benefit from a rear spoiler. They could all then improve the effectivenes of their front spoilers, and go even faster.
The best use of our set of PCS rules is to opimize what you can do. Make a front lip, that can be replaced, on the bottom of your spoiler. Allow the track to wear it down. That will set your clearance. Lower the front of the car, until you start deteriorating your handling. Then try to lower the rear to restore the handling. Don't forget mechanical grip is more important than aero grip with these cars. Reduce internal drag on the front radiator. Make maximum use of as little air into the car as possible. Seal all air leaks, you can get by with less air intake. Front splitters are allowed. But, they do no good if they increase aero oversteer, because the back now doesn't stick as well as the front. A tray behind the radiator to the engine may help help a little, because it reduces turbulence in that area. But in some cases it may reduce air flow thru the radiator by decreasing air flow exit from the radiator. OOOPS, data geek needed here... The rules limit that kind of panel, it must not go beyond the front of the wheel opening. But wait, many cars have a panel there when new from the dealer. Did your car have one? A front ground plane panel under and behind your front spoiler, an inch off the ground generates HUGE downforce. Why do the GT1, TransAm and GTO cars have such a large rear wing? To restore aero balance. Along with rear ducting under the rear of the car. I am surprised that I don't see more Prod cars with custom fuel cells. The underside of the cell should be as wide as possible, not be much lower than your rear valance, and as close as possible to reducing the air spaces behind your rear axle and the gaps between the sides of your lower fender panels. Can you get a fuel cell 7" - 10" deep and wide enough? That would require 2 fuel pumps and fuel check valves to insure pickup in the turns. Who says the fuel cell bladder should be as large as the canister containing it?
How big, or small, are your side mirrors? Have you any poorly fitting bodywork adding drag? How much drag around the windshield area, can you clean it up? Big honking fender flares look neat. Especially to the driver of a similar car, using narrow bodywork, as he passes you going down the long straights.
I have read many books, but none of them stand out to me as better than any of the others. It is just accumulated knowledge and spending time in GT1, TranAm and IMSA GTO. When I get a few minutes I will go back to the Mulsanne website listed in some comments above.
Data acquisition and the ability to interpret it and utilize it is critical. The ability to get air pressure readings in all areas leads to what is needed and where to put it. There are too many variances between cars to say one thing works on all of them. If I had a Morgan or MG TD, I would put louvers on the rear of the fenders to reduce parasitic/parachute drag and some lift. But, then there is sooo much turbulence behind the fenders on those cars, because the hood side louvers are venting and mixing with the low pressure area behind and outside the rear of the fenders. OOPS, did that negate the drag of the fender? It's all interconnected.
There are lots of subtle aero tricks that have been used to improve aero quality. The Trans Am & GTO cars once had the trailing edge of the front wheel opening, from about axle height and down, angling in towards the chassis frame rails. It did not drop straight down from the widest point of the fender, it tapered inwards. It reduced turbulence in the wheel well and assisted in venting air from under the front of the car. Rules ulitmately removed that option. They then started using carefully rolled lips at the bottom rear of the wheel opening to minimize turbulence in that area. Can you reduce the lower trailing aero exposure of your front or rear fenders in that area? Can you seal off behind the tire, and under your fenders? It acts much like a drag chute in that dark area, behind the tire and in front of the door, building pressure/drag as you go faster. If you can't use vents in that area, seal it off to reduce the drag build up. A simple piece of flat aluminum is all that is needed. You want air over or around the car, not under it or in the large body cavities.
Within the Prod car rules makers there is an undercurrent to minimze advancing aero tech advances. They actually had to write into the rules the use of a front spoiler. It is difficult to work into the rules a simple flat panel rear spoiler, such as NASCAR uses. It is inexpensive and effective. But, it will not benefit the front wheel drive sedans in the classes. But it would really help my tail happy RX7 in high speed sweeping turns like T9 at Roebling Road. The 240Z and Spitfire would also benefit from a rear spoiler. They could all then improve the effectivenes of their front spoilers, and go even faster.
The best use of our set of PCS rules is to opimize what you can do. Make a front lip, that can be replaced, on the bottom of your spoiler. Allow the track to wear it down. That will set your clearance. Lower the front of the car, until you start deteriorating your handling. Then try to lower the rear to restore the handling. Don't forget mechanical grip is more important than aero grip with these cars. Reduce internal drag on the front radiator. Make maximum use of as little air into the car as possible. Seal all air leaks, you can get by with less air intake. Front splitters are allowed. But, they do no good if they increase aero oversteer, because the back now doesn't stick as well as the front. A tray behind the radiator to the engine may help help a little, because it reduces turbulence in that area. But in some cases it may reduce air flow thru the radiator by decreasing air flow exit from the radiator. OOOPS, data geek needed here... The rules limit that kind of panel, it must not go beyond the front of the wheel opening. But wait, many cars have a panel there when new from the dealer. Did your car have one? A front ground plane panel under and behind your front spoiler, an inch off the ground generates HUGE downforce. Why do the GT1, TransAm and GTO cars have such a large rear wing? To restore aero balance. Along with rear ducting under the rear of the car. I am surprised that I don't see more Prod cars with custom fuel cells. The underside of the cell should be as wide as possible, not be much lower than your rear valance, and as close as possible to reducing the air spaces behind your rear axle and the gaps between the sides of your lower fender panels. Can you get a fuel cell 7" - 10" deep and wide enough? That would require 2 fuel pumps and fuel check valves to insure pickup in the turns. Who says the fuel cell bladder should be as large as the canister containing it?
How big, or small, are your side mirrors? Have you any poorly fitting bodywork adding drag? How much drag around the windshield area, can you clean it up? Big honking fender flares look neat. Especially to the driver of a similar car, using narrow bodywork, as he passes you going down the long straights.
JohnMcNaughton
Well-known member
Recommended reading.
Carroll Smith, "Tune to Win" and "Engineer to Win". I am a student of Carroll Smith and his "to Win" series of books. Good reading for the non-engineer or non-professionally trained mechanic. It organizes your thinking on how to properly care for and feed a race car. I read his early articles in Sports Car Graphic magazine. When I finally met him asked about when he would be writing a book. I have an autographed copy of his first book, and all of his other books. Highly recommended. Also listed in the reference list of Competition Car Downforce.
I have a copy of Competition Car Downforce, by Simon McBeath, forward by Gordon Murray. It is a typical British car book. Covers formula, sport racer, prototype, GT and Production based forms of race cars. Well illustrated with pictures, charts and diagrams, 208 pages. Good reading with what you may be looking for. It has a broad approach to all types of race cars with chapters on spoilers, wings, under trays, DIY construction techniques, case studies and references. It even has a picture of a fully Aero "optimized" Lotus 7 and a bug eyed Sprite! You will receive a well rounded presentation of how aero works and what shouldn't work. It will not address any specific car, but you can make more informed decisions after reading the book.
When I checked Amazon.com, it is still available. Along with a few other good references. Would now like to read New Directions in Race Car Aerodynamics, by Joseph Katz.
Copy the link below to your browser:
http://www.amazon.com/s/ref=nb_sb_ss_i_ ... ooks%2C211
Carroll Smith, "Tune to Win" and "Engineer to Win". I am a student of Carroll Smith and his "to Win" series of books. Good reading for the non-engineer or non-professionally trained mechanic. It organizes your thinking on how to properly care for and feed a race car. I read his early articles in Sports Car Graphic magazine. When I finally met him asked about when he would be writing a book. I have an autographed copy of his first book, and all of his other books. Highly recommended. Also listed in the reference list of Competition Car Downforce.
I have a copy of Competition Car Downforce, by Simon McBeath, forward by Gordon Murray. It is a typical British car book. Covers formula, sport racer, prototype, GT and Production based forms of race cars. Well illustrated with pictures, charts and diagrams, 208 pages. Good reading with what you may be looking for. It has a broad approach to all types of race cars with chapters on spoilers, wings, under trays, DIY construction techniques, case studies and references. It even has a picture of a fully Aero "optimized" Lotus 7 and a bug eyed Sprite! You will receive a well rounded presentation of how aero works and what shouldn't work. It will not address any specific car, but you can make more informed decisions after reading the book.
When I checked Amazon.com, it is still available. Along with a few other good references. Would now like to read New Directions in Race Car Aerodynamics, by Joseph Katz.
Copy the link below to your browser:
http://www.amazon.com/s/ref=nb_sb_ss_i_ ... ooks%2C211
JohnMcNaughton
Well-known member
Enjoy it, I am always available for assistance.
FYI, my first car was a one year old 63 MGB. Drove it thru the service and most of college. Replaced it with a Lotus Europa. Enjoyed both immensely, and other than an occasional Corvette, 67 427 coupe and 84 coupe. Never had another "street toy" to drive on a daily basis. Got wrapped up in race cars, B/S 510, B/P AND GT1 Corvettes, drove the Daytona 24 Hours, and crewing for TRANS AM and IMSA GTO, most with podium finishes. And 2 RX7's for my wife in SSA, ITA, ITS and E/P, from then until I recently sold our E/P RX7. We both used the last RX7 as our final racing car. All forms of racing were goodStrangely, I enjoyed the production racing and drivers more than the other racing. They seemed to put more heart into their cars and driving. The bigger cars and drivers were at times way too serious to enjoy it as much...
FYI, my first car was a one year old 63 MGB. Drove it thru the service and most of college. Replaced it with a Lotus Europa. Enjoyed both immensely, and other than an occasional Corvette, 67 427 coupe and 84 coupe. Never had another "street toy" to drive on a daily basis. Got wrapped up in race cars, B/S 510, B/P AND GT1 Corvettes, drove the Daytona 24 Hours, and crewing for TRANS AM and IMSA GTO, most with podium finishes. And 2 RX7's for my wife in SSA, ITA, ITS and E/P, from then until I recently sold our E/P RX7. We both used the last RX7 as our final racing car. All forms of racing were goodStrangely, I enjoyed the production racing and drivers more than the other racing. They seemed to put more heart into their cars and driving. The bigger cars and drivers were at times way too serious to enjoy it as much...
Dave Craddock
New member
Don/others, you can probably vent eng compartment air thru the fresh air vent on the cowl, this would require removing some sheet metal on the firewall under the hood, so far I've only seen that done by one guy(who shall remain nameless).
Dave
BTW; I'll see you at Grattan.
Dave
BTW; I'll see you at Grattan.
JohnMcNaughton
Well-known member
If you tie some string around the vent at the base of the windshield, which way does the string blow? On most cars, that area usually has a slightly higher air pressure level and is used as an air source for the carburetor. I think that was the source of cooler fresh air into my MGB during the summer, before the British invented A/C. (No, wait, that was their A/C)
One thing that was not discussed earlier. Placing small, flat, sheetmetal tabs ahead of the front tires, mounted vertically on the front spoiler wheel opening lip. It cannot exceed the vertical line of sight rule for how far it can protrude. It will create a little bit of negative pressure to the rear of it, drawing more air from under the front of the car and exiting out in front of the wheel. Don't expect signifcant results, this is only a minor tuning step for cars that have rules allowing greater aero tools. But, it could also assist with hot summer cooling problems. If you have a little bit of high speed, front end, lack of sharpness in steering response, such as the kink at Road America or at Road Atlanta entering the pit straight and then T1, this could help a little.
I have seen some GT1 cars experiment with a larger front splitter with very good affect. But, again, it must be offset with some addtional rear down force to restore aero balance. One attempt proved to be way too large of a splitter. It caused such an increase of air presure into the grill opening that it ruptured the sealing of the radiator shroud and separated the brake cooling duct hoses from their mounts....
One thing that was not discussed earlier. Placing small, flat, sheetmetal tabs ahead of the front tires, mounted vertically on the front spoiler wheel opening lip. It cannot exceed the vertical line of sight rule for how far it can protrude. It will create a little bit of negative pressure to the rear of it, drawing more air from under the front of the car and exiting out in front of the wheel. Don't expect signifcant results, this is only a minor tuning step for cars that have rules allowing greater aero tools. But, it could also assist with hot summer cooling problems. If you have a little bit of high speed, front end, lack of sharpness in steering response, such as the kink at Road America or at Road Atlanta entering the pit straight and then T1, this could help a little.
I have seen some GT1 cars experiment with a larger front splitter with very good affect. But, again, it must be offset with some addtional rear down force to restore aero balance. One attempt proved to be way too large of a splitter. It caused such an increase of air presure into the grill opening that it ruptured the sealing of the radiator shroud and separated the brake cooling duct hoses from their mounts....
Dave Craddock
New member
John, unless the car is a GT, it probably has no windshield.
Dave
Dave
JohnMcNaughton
Well-known member
Ok, without the windshield:
If you tie some string around the vent at the base of the windshield, which way does the string blow?
If you tie some string around the vent at the base of the windshield, which way does the string blow?
JohnMcNaughton":6o0ksezn said:
Surely this would depend on the windshield.
In a road MGB with a full windshield, I read that air flows into the opening. This would mean to me that pressure under the hood at that point was lower than pressure over the hood at that point. The confused air above the opening at that point creates a higher pressure zone. String flows forward.
At the other end of the spectrum, if a car has a lay-down windscreen I suspect that the reverse would happen. The string would flow to the rear. Airflow would be smoother and faster, and the pressure above the opening would be less than below. Hot air would be pulled out. Thus the racer's trick of using the opening to vent hot air under the hood, which I have heard before.
So, my sense of this is the same as Dave's.
John?
JohnMcNaughton
Well-known member
On a stock MGB the air flows from the windshield vent into the interior of the car, over the transmission tunnel. It is assisted by a fan motor, as needed.
With or without the windshield, you will need to know the pressure differential of the air over the top vent and the air pressure at the exit area under the hood to accurately determine the effectiveness of the venting you are designing. The most accurate method is with data acquisition on the track, using manometer/pressure strips with a recording of the speed of the car, as the pressure changes. In the absence of that equipment, use your video recorder to monitor a manometer gauge in each location. Or, just record the motion of this magic string taped to the hood and windshield vents. Is the air over the vent moving, showing downward pressure into the vent, or lifting over the vent. Test it with the interior vent open and again with it closed. Any other suggestions for monitoring pressure under the hood? It would need to be in the area you plan to connect to the windshield vent.
If you have an open car with a stock vent opening forward of the windshield, and have replaced the windshield with a low race windshield, you will still need to identify how that small windshield lip is affecting areo flow and pressure over the vent.
With or without the windshield, you will need to know the pressure differential of the air over the top vent and the air pressure at the exit area under the hood to accurately determine the effectiveness of the venting you are designing. The most accurate method is with data acquisition on the track, using manometer/pressure strips with a recording of the speed of the car, as the pressure changes. In the absence of that equipment, use your video recorder to monitor a manometer gauge in each location. Or, just record the motion of this magic string taped to the hood and windshield vents. Is the air over the vent moving, showing downward pressure into the vent, or lifting over the vent. Test it with the interior vent open and again with it closed. Any other suggestions for monitoring pressure under the hood? It would need to be in the area you plan to connect to the windshield vent.
If you have an open car with a stock vent opening forward of the windshield, and have replaced the windshield with a low race windshield, you will still need to identify how that small windshield lip is affecting areo flow and pressure over the vent.
Protech Racing
Well-known member
I have made a "helicopter cam". It is a 70in long tripod that attaches to the cage of the car.
I then tape streamers to the hood,top of the cut windshield, etc, and front end parts of the car to watch the airflow . This is the Chumpcar, with a 6in tall screen, no roof.
I get very little airflow down into the seat area. ( the rear deck area has been removed)
I get lots of air from the hood vents.
Air leaves the under hood area from the base of the windshield. (maybe the "Gurney" strips at the vent edge , help here)
It has a large airdam with small canards near the front tires.
The airdam's main job is to feed the(water misted) brake ducts, as the races are 14hr.
I am considering adding a vent into the driver area from the pass fender well, to lessen the air swirl in the footwell . The pass floor will be the landing zone for the stones, but dust is the main reason it is not there yet. As it is now, rain does not really bother the driver.
Most of race car engineering is some form of; "sq in. of involvement". For Air, less is more.
I wil try to post some pics of this testing on my website. The trans is getting a taller gear this week and we are running nextweek @ Sebring, so it may be a week or two.
We also did the streamer/camera thing with my airplane videoed from a car. The deal here is to use contrasting streamers, and get close. I roll it down the 6000ft runway of my local airport.
I then tape streamers to the hood,top of the cut windshield, etc, and front end parts of the car to watch the airflow . This is the Chumpcar, with a 6in tall screen, no roof.
I get very little airflow down into the seat area. ( the rear deck area has been removed)
I get lots of air from the hood vents.
Air leaves the under hood area from the base of the windshield. (maybe the "Gurney" strips at the vent edge , help here)
It has a large airdam with small canards near the front tires.
The airdam's main job is to feed the(water misted) brake ducts, as the races are 14hr.
I am considering adding a vent into the driver area from the pass fender well, to lessen the air swirl in the footwell . The pass floor will be the landing zone for the stones, but dust is the main reason it is not there yet. As it is now, rain does not really bother the driver.
Most of race car engineering is some form of; "sq in. of involvement". For Air, less is more.
I wil try to post some pics of this testing on my website. The trans is getting a taller gear this week and we are running nextweek @ Sebring, so it may be a week or two.
We also did the streamer/camera thing with my airplane videoed from a car. The deal here is to use contrasting streamers, and get close. I roll it down the 6000ft runway of my local airport.
Protech Racing
Well-known member
Up date. The Turbo Jett@ Sebring, would pull hard to 119, but no more. I have too much downforce with the canards, Splitter scoops etc. The car reached 119 at every straight onthe track, in about 1200 ft or less.
In the video, the canard streamers are pointed up at slow speeds, and straight back about around 70 or more. They are stalled hard IMHO.
Mon am ;" Ihave a plate on this". I find a long straight road and start some coast down testing. Being as I have enough issues with the car running on the street, I use 60mph as the top speed and coast until 45mph( per GPS.) 3 passes each direction, average about 14.7sec. I drill off the canards , the next 6 passes up to high 15.8-16.
(The same car ran 117 @ daytona with about half of the torque.)
I will let the nose back down 1 in,remove the pass seat, add a tonnau over the pas area. and retest, with a full tank again,maybe fri.
The ribbon streamers are a big help in the video, esp the rear deck area. A small change in the spoiler angle makes a big diff over the rear face.
I will post the website for the coast down info next edit. MM
In the video, the canard streamers are pointed up at slow speeds, and straight back about around 70 or more. They are stalled hard IMHO.
Mon am ;" Ihave a plate on this". I find a long straight road and start some coast down testing. Being as I have enough issues with the car running on the street, I use 60mph as the top speed and coast until 45mph( per GPS.) 3 passes each direction, average about 14.7sec. I drill off the canards , the next 6 passes up to high 15.8-16.
(The same car ran 117 @ daytona with about half of the torque.)
I will let the nose back down 1 in,remove the pass seat, add a tonnau over the pas area. and retest, with a full tank again,maybe fri.
The ribbon streamers are a big help in the video, esp the rear deck area. A small change in the spoiler angle makes a big diff over the rear face.
I will post the website for the coast down info next edit. MM