Active Aero Part II
Discussion
I noticed a rather extended discussion regarding Active Aero, however I thought I'd start a new topic as that topic was more concerned with electrically actuated wings acting as airbrakes. All I know is I don't know quite enough about aerodynamic models to add anything, but it seems quite a bit of trouble.
In another bit of "banned from motorsport" technology, how about something that really worked well, fans?
The Macca F1 had a couple of electric fans running all the time, at least the road car did. If I remember correctly they were used to counteract underbody lift by preventing the formation of a slower moving boundary layer of air, essentially blowing air laterally. But I do remember a certain F1 car with fans set up for suction driving so well in its first race that they banned it immediately.
It's a bit left field, but it might be a nice way to run huge downforce without a wing at all, pretty low weight considering the possible benefits. Would require some serious aero and suspension knowledge...
Speaking of underbody effects, has anyone fashioned a more complete underbody tray for their ultima? Any aero engineers on the board? Someone who knows their venturis? What's the factory stance on underbody effects/tunnels? I'd love to see a downforce solution for the ultima which didn't entail that rear wing.
Oh an this is my first post, my name is Hans, I'm from New York, and I've not yet taken the Ultima plunge, although I have considered it a couple of times over the years, and have a bit of a renewed interest recently. Having browsed through the posts, I can tell that you all are a fine bunch of enthusiastic owners, and amazingly helpful. My apologies for the long post, and all the best.
In another bit of "banned from motorsport" technology, how about something that really worked well, fans?
The Macca F1 had a couple of electric fans running all the time, at least the road car did. If I remember correctly they were used to counteract underbody lift by preventing the formation of a slower moving boundary layer of air, essentially blowing air laterally. But I do remember a certain F1 car with fans set up for suction driving so well in its first race that they banned it immediately.
It's a bit left field, but it might be a nice way to run huge downforce without a wing at all, pretty low weight considering the possible benefits. Would require some serious aero and suspension knowledge...
Speaking of underbody effects, has anyone fashioned a more complete underbody tray for their ultima? Any aero engineers on the board? Someone who knows their venturis? What's the factory stance on underbody effects/tunnels? I'd love to see a downforce solution for the ultima which didn't entail that rear wing.
Oh an this is my first post, my name is Hans, I'm from New York, and I've not yet taken the Ultima plunge, although I have considered it a couple of times over the years, and have a bit of a renewed interest recently. Having browsed through the posts, I can tell that you all are a fine bunch of enthusiastic owners, and amazingly helpful. My apologies for the long post, and all the best.
Well the Standard wing looks lovly IMHO, and tends to make the car looks so sexy from the rear.
But I have looked into making a rear under tray before, but the chassis rails at the back are to low (i.e. level with the rest of the chassis), to make any rasied defuser at the back.
BUT, if you look under the car, the clearances ( Hieght )at back of the car compared to the front are 2" more. So the chassis is allready at an angle and making a pressure drop towards to rear anyway if you fit a flat pan under the engine that is. Factory standard as they say.... But keep those ideas coming this is how things are developed....
But I have looked into making a rear under tray before, but the chassis rails at the back are to low (i.e. level with the rest of the chassis), to make any rasied defuser at the back.
BUT, if you look under the car, the clearances ( Hieght )at back of the car compared to the front are 2" more. So the chassis is allready at an angle and making a pressure drop towards to rear anyway if you fit a flat pan under the engine that is. Factory standard as they say.... But keep those ideas coming this is how things are developed....
good idea if you ask an ideot like me. i have also seen that F1 car that had a huge fan that pulled air from under the car to increas down force. if you mounted the fans in a flat undertry and mounted them just behind the bulkhead, they would provide some nice cooling air diredctly on the egnine block aswell as ading the downforce. Could help with some of the overheating problems.
thanks Chris.
thanks Chris.
If memory serves, both the Brabham F1 car from the 78 season and the Mclaren F1 road car were children of Gordon Murray, that man must love fans, and considering how well those cars behaved, they must work pretty well. But considering their respective R&D and production budgets, fans and other active aero are probably a bit beyond the scope of my own tinkering.
I think actual suction is probably asking for trouble, will distort the pitch and roll centers/ center of gravity, would require some serious engineering, as it would seriously affect the overall dynamics of not just the aero but the whole suspension. Still I think that it might not be the most expensive thing to try out, if it could go under the motor (I've seen a couple of build diaries with custom built pans under the motor, nice for stiffness too).
The Macca F1-style "boundary layer" fan setup is probably easier to engineer, however its effectiveness sans an underbody tray is likely limited, possibly counterproductive. And it seems there might not be enough room for the effects.
I'm on again, off again with respect to the appearance of the wing. It would be nice if the wing could go on for track day and come off again for streets (and be strong and seamless looking). I really love the look of the car without it, and in fact one of the things that turned me off to the Sports back in the day was the wind and it mounting. But at 180 mph under heavy braking, I'll take the wing any day. Does anyone here run without the wing? Any impressions of overall stability or lack thereof?
Thanks guys for your responses. ..ht
I think actual suction is probably asking for trouble, will distort the pitch and roll centers/ center of gravity, would require some serious engineering, as it would seriously affect the overall dynamics of not just the aero but the whole suspension. Still I think that it might not be the most expensive thing to try out, if it could go under the motor (I've seen a couple of build diaries with custom built pans under the motor, nice for stiffness too).
The Macca F1-style "boundary layer" fan setup is probably easier to engineer, however its effectiveness sans an underbody tray is likely limited, possibly counterproductive. And it seems there might not be enough room for the effects.
I'm on again, off again with respect to the appearance of the wing. It would be nice if the wing could go on for track day and come off again for streets (and be strong and seamless looking). I really love the look of the car without it, and in fact one of the things that turned me off to the Sports back in the day was the wind and it mounting. But at 180 mph under heavy braking, I'll take the wing any day. Does anyone here run without the wing? Any impressions of overall stability or lack thereof?
Thanks guys for your responses. ..ht
As a pilot (for fun), this is a very interesting thread to me. I don't know why general automotive manufacturers and motorsports have not increased their development in this area. BTW, the Reno Air Races started this week. www.airrace.org Those speed-freaks will be making laps 50 feet off the ground at over 500 mph! And, sometimes they are only a few feet apart!!
I was thinking about this thread recently, after reading a book called "Race Car Aerodynamics" by Joseph Katz. Although it is very math-intensive, just the concepts open one's eyes to the possibilities. So, I am driving along in my land-yacht (compared the GTR) and it hits me like a ton of bricks. All of this time, every effort that I have seen/read about has been geared towards generating downforce so the tires can generate greater traction, or to reduce/increase parasitic drag. Attempts at active aero combined these efforts into an adjustable downforce and drag-producing element.
But, this approach may be totally off base. When an airplane goes around a corner (generally), there are three axis around which it rotates; X, Y, and Z.
Pitch - The tail horizontal stabilizer and elevator work to adjust the nose up and down, which is the same force in a car when you step on the brakes or accelerate,
Yaw - The vertical stabilizer and rudder work to keep the tail behind nose, the forces that make a car spin, and...
Roll - the wings and ailerons control roll, which we hope we don't need in a car!
Such are the forces on an airplane in it's 3-dimensional world. Luckily, we need only be concerned about pitch and yaw, unless you are a dirt-racer.
But, to some degree, I think those "Outlaw Series" dirt-racers with the huge air foils are on to something. If you are not familiar, here's a photo (136k) of some "Outlaw Series" cars. These cars spend their entire time oversteering; sliding around an oval counter-clockwise. Notice how their aerodynamics (their vertical stabilizers) are staggered to maximize surface area? Those things are used like sails in the negative direction to keep them from moving to the right.
This type of concept is a little radical for a street rod, but... The latest advances in aviation wing structures use mechanical elements under the wing's skins to actually deform the shape of the wing, in addition to ailerons, flaps, etc. If moving air has less pressure, when I turn right, I want less pressure on the right. So, why not incorporate that into automotive design (especially for race cars). Why depend on the tires for much more than to stop, accelerate, and keep the car off the ground?
Sorry for the long post, but I think a mechanical panel could be made to pop out of the side of a car to enhance it's ability to turn. The best possible scenario would be to slip-joint the entire car chassis and body so that the sides could bend, making the entire shape of the car body into a wing.
Okay, enough crazy talk. How am I going to do that?!
I was thinking about this thread recently, after reading a book called "Race Car Aerodynamics" by Joseph Katz. Although it is very math-intensive, just the concepts open one's eyes to the possibilities. So, I am driving along in my land-yacht (compared the GTR) and it hits me like a ton of bricks. All of this time, every effort that I have seen/read about has been geared towards generating downforce so the tires can generate greater traction, or to reduce/increase parasitic drag. Attempts at active aero combined these efforts into an adjustable downforce and drag-producing element.
But, this approach may be totally off base. When an airplane goes around a corner (generally), there are three axis around which it rotates; X, Y, and Z.
Pitch - The tail horizontal stabilizer and elevator work to adjust the nose up and down, which is the same force in a car when you step on the brakes or accelerate,
Yaw - The vertical stabilizer and rudder work to keep the tail behind nose, the forces that make a car spin, and...
Roll - the wings and ailerons control roll, which we hope we don't need in a car!
Such are the forces on an airplane in it's 3-dimensional world. Luckily, we need only be concerned about pitch and yaw, unless you are a dirt-racer.
But, to some degree, I think those "Outlaw Series" dirt-racers with the huge air foils are on to something. If you are not familiar, here's a photo (136k) of some "Outlaw Series" cars. These cars spend their entire time oversteering; sliding around an oval counter-clockwise. Notice how their aerodynamics (their vertical stabilizers) are staggered to maximize surface area? Those things are used like sails in the negative direction to keep them from moving to the right. This type of concept is a little radical for a street rod, but... The latest advances in aviation wing structures use mechanical elements under the wing's skins to actually deform the shape of the wing, in addition to ailerons, flaps, etc. If moving air has less pressure, when I turn right, I want less pressure on the right. So, why not incorporate that into automotive design (especially for race cars). Why depend on the tires for much more than to stop, accelerate, and keep the car off the ground?
Sorry for the long post, but I think a mechanical panel could be made to pop out of the side of a car to enhance it's ability to turn. The best possible scenario would be to slip-joint the entire car chassis and body so that the sides could bend, making the entire shape of the car body into a wing.
Okay, enough crazy talk. How am I going to do that?!
Builder - very intersting thoughts, although I do believe more than one race car has twisted, for lack of a better term, flapjacked maybe, running left / right wings. I guess cause you do have to deal with roll in a car just like a plane, just when you roll it's into the ground.
I saw an article just now googling about this topic, the source (popular science) scares me since by their reckoning we should all be filling our personal cold fusion powered hovercraft with pump tritium for our morning commute to Mars, but the author is the real deal so: www.popsci.com/popsci/futurecar/article/0,20642,681879,00.html
but as far as crazy talk goes, with cheap actuators and pretty cheap grp processes, and cheap computers, all you need is engineering and testing, the tools to execute are very available nowadays. A hollywood 3D movie magic friend of mine once tried to convince me that sufficiently detailed CAD diagrams of the car plus Silicon Graphics Maya software could model aero better than all but the most advanced tunnels, and measure effectiveness at speed across various scenarios (cornering, braking, accelerating, dynamic transitions). He might have something there, as certain cars, the Saleen sportscar, which is as close to a an old school group c car as i've seen lately, comes to mid as having been built very rapidly in a similar fashion, so they could get thousands of hours of simulation done in seconds of real time.
..ht
>> Edited by htny on Tuesday 14th September 09:48
I saw an article just now googling about this topic, the source (popular science) scares me since by their reckoning we should all be filling our personal cold fusion powered hovercraft with pump tritium for our morning commute to Mars, but the author is the real deal so: www.popsci.com/popsci/futurecar/article/0,20642,681879,00.html
but as far as crazy talk goes, with cheap actuators and pretty cheap grp processes, and cheap computers, all you need is engineering and testing, the tools to execute are very available nowadays. A hollywood 3D movie magic friend of mine once tried to convince me that sufficiently detailed CAD diagrams of the car plus Silicon Graphics Maya software could model aero better than all but the most advanced tunnels, and measure effectiveness at speed across various scenarios (cornering, braking, accelerating, dynamic transitions). He might have something there, as certain cars, the Saleen sportscar, which is as close to a an old school group c car as i've seen lately, comes to mid as having been built very rapidly in a similar fashion, so they could get thousands of hours of simulation done in seconds of real time.
..ht
>> Edited by htny on Tuesday 14th September 09:48
mrloudly's right, you'd have to have a lot of computing going on to make it all work with two hands and two feet, but have you seen all those propsed drive by wire, non steering wheel setups from the big manufacturers, which use a yoke for throttle, braking and steering. leaves the feet free for rudder no? Now let's see them get one of those around a race track (you can count the F1 guys out, can't drive two footed anymore) ..ht
Ha-Ha! I know. It's pure lunacy. And I agree with the computer modeling. I sold CAD systems for about 10 years. Anyways…it’s an interesting topic. Although, perhaps a little off topic here.
Albeit slowly, an airplane can make an “uncoordinated turn” and turn flat while flying. Only the rudder is used. Ailerons, the large wing controls, are used to bank/roll the plane into a “coordinated turn” to counteract the G-force. If all other surface control systems fail in an airplane, the pilot can still turn the plane with only the rudder. It’s sort of like skidding the rear tires around a corner on ice...not much G-force and lots of yaw (over-steer). In an uncoordinated turn, the sideways G-forces are then felt by the occupants, and the rudder experiences greater loads.
The roll factor could be virtually eliminated by the Bernoulli effect of the panel(s) that would open on the side (and/or top) of the car. The panel opening size (thus, amount of lift) would be controlled by steering position and speed sensors. The side of the car, taking on a wing-like form, would be "sucked", by Bernoulli, around the corner. (Bernoulli sucks!
) Anyway... The goal would be to eliminate the roll factor. The tendency for a car to roll is due to the inertia of the car wanting to continue in a straight line, while the tires want something otherwise. There's nothing to push (or pull) against the inertia of the car except the tires. Since the tires' friction points are at the very bottom of the weight, roll is induced. Counteract that with equal forces at the top, and the roll is eliminated. Still, the friction of the tires is what’s making the car turn and is a limiting factor. Augment turning force by opening panels to channel air, and we could increase turning forces an X-factor.
I know…it’s all hyperbole, but what the heck! Chime in, if you think any of this is possible and we’ll change the auto industry forever!
Albeit slowly, an airplane can make an “uncoordinated turn” and turn flat while flying. Only the rudder is used. Ailerons, the large wing controls, are used to bank/roll the plane into a “coordinated turn” to counteract the G-force. If all other surface control systems fail in an airplane, the pilot can still turn the plane with only the rudder. It’s sort of like skidding the rear tires around a corner on ice...not much G-force and lots of yaw (over-steer). In an uncoordinated turn, the sideways G-forces are then felt by the occupants, and the rudder experiences greater loads.
The roll factor could be virtually eliminated by the Bernoulli effect of the panel(s) that would open on the side (and/or top) of the car. The panel opening size (thus, amount of lift) would be controlled by steering position and speed sensors. The side of the car, taking on a wing-like form, would be "sucked", by Bernoulli, around the corner. (Bernoulli sucks!
) Anyway... The goal would be to eliminate the roll factor. The tendency for a car to roll is due to the inertia of the car wanting to continue in a straight line, while the tires want something otherwise. There's nothing to push (or pull) against the inertia of the car except the tires. Since the tires' friction points are at the very bottom of the weight, roll is induced. Counteract that with equal forces at the top, and the roll is eliminated. Still, the friction of the tires is what’s making the car turn and is a limiting factor. Augment turning force by opening panels to channel air, and we could increase turning forces an X-factor. I know…it’s all hyperbole, but what the heck! Chime in, if you think any of this is possible and we’ll change the auto industry forever!
There is one vital piece of info missing. An aeroplane is part of the mass in which it travels (air) therefore all control deflections will be against that mass and thus will always display a constant repeatable effect (subject to air density and speed)(Excluding extreme windshear situations ((and we all know what that can lead to)). If you start using aerodynamic forces to steer vehicles you (the car) are attached to a fixed mass (Earth) and the controls will be subjected to a moving variable mass (air). To correlate the effects of two controls (aerodynamic/steering) operating in two mass's (Earth/atmosphere) into a constant predictable result would be very difficult.
Jeez I've impressed myself with that one.....
Jeez I've impressed myself with that one.....
mrloudly said:Ha-Ha! And well you should! That's a very good point. The control computer would probably need to have density altitude compensation tables, or something like that. Also, it would probably need airspeed vs. ground to determine relative wind. It's complicated. Not impossible, but definitely impractical for the average Ultima builder! Multiple pitot tubes and static ports, angle of attack, etc.
To correlate the effects of two controls (aerodynamic/steering) operating in two mass's (Earth/atmosphere) into a constant predictable result would be very difficult.
Jeez I've impressed myself with that one.....
The car, while rolling on the ground, would "fly" sideways. Jeez, with the right system, you wouldn't even need to mechanically turn the tires (except at low speeds). They would turn like a shopping-cart!
Occasional gusts of wind?
The B6 Sport has a nice rear diffuser and undertray. The ultima nor stealth has the little vents in the front wheel arches that the maccy does. I don't know if that would benefit or not. BTW I love the 2004 stealth, just 4 pics with lots of nifty aero features.
www.racecar.co.uk/stealth/mk2image1.htm
Alot of the suction and venturi stuff requires crazy low ride heights to be very effective.
Race Car Aerodynamics by Joseph Katz would be a good place to start. I quite after trying to understand the reynolds number.
The B6 Sport has a nice rear diffuser and undertray. The ultima nor stealth has the little vents in the front wheel arches that the maccy does. I don't know if that would benefit or not. BTW I love the 2004 stealth, just 4 pics with lots of nifty aero features.
www.racecar.co.uk/stealth/mk2image1.htm
Alot of the suction and venturi stuff requires crazy low ride heights to be very effective.
Race Car Aerodynamics by Joseph Katz would be a good place to start. I quite after trying to understand the reynolds number.
PiB said:Yup, that's a booger! After the 10th grey page, I stopped trying to work the formulae; rather just absorb the concepts. Coming from the CAD world of computing, I thought I knew a little math! The math in that book probably borders on
Race Car Aerodynamics by Joseph Katz would be a good place to start. I quite after trying to understand the reynolds number.
doctoral level.Consider me hardheaded... I received the following email from Paul VanValkenburgh, the engineer and writer quoted in the popular science article:
">...question is, is it possible to effectively
>employ such suction effects in a road going
>car,i.e. one which is not skirted down to the
>road’s surface?
Possible, but not at all practical, or I would have done it decades ago. Coincidentally, I was making notes for an article/editorial about that very topic.
Paul"
">...question is, is it possible to effectively
>employ such suction effects in a road going
>car,i.e. one which is not skirted down to the
>road’s surface?
Possible, but not at all practical, or I would have done it decades ago. Coincidentally, I was making notes for an article/editorial about that very topic.
Paul"
PiB said:
Occasional gusts of wind?
The B6 Sport has a nice rear diffuser and undertray. The ultima nor stealth has the little vents in the front wheel arches that the maccy does. I don't know if that would benefit or not. BTW I love the 2004 stealth, just 4 pics with lots of nifty aero features.
www.racecar.co.uk/stealth/mk2image1.htm
Alot of the suction and venturi stuff requires crazy low ride heights to be very effective.
Race Car Aerodynamics by Joseph Katz would be a good place to start. I quite after trying to understand the reynolds number.
I have seen that car and it really is nice, Steve Smith did all the body work and helped Mark build the car being as it's the only road going Stealth out there, it's a shame Steve is no longer with ultima as I feel the GTR would be even better now with his ideas and development, only my opinion though. He did a nice job on that body work and it's so much better in the flesh.
Cheers.
Unfortunately for your Bernoulli theory to work the car would have to look like a wing on its side and you would vary the shape of either side relative to the other to direct the lift- without a perfect joining of the two streams of air at the trailing edge you don't have any lift I don't think.
Active aero is all well and good but it tends to be best used in things like Porker turbos and Crossfires that look suspiciously like the aforementioned wings and have a rotate velocity of somewhere around the speed limit! And are you going to do 5 runs of your trip to the supermarket to set up your wings just so before attempting the real run? :P
Active aero is all well and good but it tends to be best used in things like Porker turbos and Crossfires that look suspiciously like the aforementioned wings and have a rotate velocity of somewhere around the speed limit! And are you going to do 5 runs of your trip to the supermarket to set up your wings just so before attempting the real run? :P
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