Top Gear - Season 19

[WingsofWar]

Originally Posted by serialk11r

I'm not convinced that those flaps are all that useful, especially the ones in front. It must take crazy powerful motors/hydraulics to actuate them though.

I think it's more that the Ariel Atom has no aero to speak of, besides that bandaid wing. Exposed wheels really suck for aero. Pagani cars have a very tapered greenhouse compared to just about all the other supercars, which is good. Upon closer inspection of some photos it appears they have some ground effects going on; The rear diffuser is really high, and the nose seems to be pretty high at the front too. That might do it.

Still, freaking fast time! They beat the McLaren! (with more power of course)

Can't wait till next episode.

slippery when it wants to be, and alters high pressure zones on the fly. Sure the Arial atom isnt exactly aerodynamic but neither is F1, did you see last years active aero test on just the 2 stage rear wing? Drivers say it made passing suddenly too easy.

Regulating 4 corners of the chassis, i think its doing quite a bit, especially up front....reminds me of Chris Rado's Scion tC with the giant spoiler on the front.

active aero in itself isn't the reason why it was fast, IMO active aero was the reason why it was so composed in accel, braking, and cornering.

[OrbitalEllipses]

Originally Posted by WingsofWar

active aero in itself isn't the reason why it was fast, IMO active aero was the reason why it was so composed in accel, braking, and cornering.

The poise it showed was INSANE. Very composed.

[roflcopter]

This may be really dumb but I thought the episodes on BBC America were like a season, or half a season behind the ones on BBC2? It always seems like the Christmas specials and things are at the wrong times.

[serialk11r]

Originally Posted by WingsofWar

slippery when it wants to be, and alters high pressure zones on the fly. Sure the Arial atom isnt exactly aerodynamic but neither is F1, did you see last years active aero test on just the 2 stage rear wing? Drivers say it made passing suddenly too easy.

Regulating 4 corners of the chassis, i think its doing quite a bit, especially up front....reminds me of Chris Rado's Scion tC with the giant spoiler on the front.

active aero in itself isn't the reason why it was fast, IMO active aero was the reason why it was so composed in accel, braking, and cornering.

Naw the difference between the tC front wing and this is that these little flaps are on the body itself, so when the front flaps deploy they create a big wake over the body of the car, which lowers the pressure over the affected parts of the car. The tC wing is high up and away from the body, so it should be more effective, and it also does more than just redirect air since it has an aerofoil shape (higher downforce).

In the rear there shouldn't be this sort of interference so it could be more useful (though the flaps are very narrow, so they still are probably not that effective due to all the air slipping past the sides).

F1 is as good as it gets given the rules, which suck. The Ariel can have better aero characteristics if they try harder, but the complete absence of panels and fairings shows they don't really care lol.

[WingsofWar]

Originally Posted by serialk11r

Naw the difference between the tC front wing and this is that these little flaps are on the body itself, so when the front flaps deploy they create a big wake over the body of the car, which lowers the pressure over the affected parts of the car. The tC wing is high up and away from the body, so it should be more effective, and it also does more than just redirect air since it has an aerofoil shape (higher downforce).

In the rear there shouldn't be this sort of interference so it could be more useful (though the flaps are very narrow, so they still are probably not that effective due to all the air slipping past the sides).

wait wait wait....when the front flaps deploy they make higher pressure over the effective areas, i saw them only deploy during braking or low speed cornering. If i'm thinking right, they serve to function as adding drag, and are modulated to effect the level of downforce, to forcefully stop the car using parachuting and or change individual air speeds to each corner of the car.
Isn't thats opposite of what your proposing, if they lower the pressure in the effective area they make the air speed velocity faster, meaning the cars forward body will be slippy. Not exactly formula you want for stoppage if you want to harness the fluidity of air to aid performance.

The tC effectively uses the same type of drag but is static, meaning it aids braking, while aiding downforce depending on the situation, but never offers low pressure areas to the car's forward body because its completely detached from the main air stream. and isn't modulated.

[serialk11r]

Originally Posted by WingsofWar

Isn't thats opposite of what your proposing, if they lower the pressure in the effective area they make the air speed velocity faster, meaning the cars forward body will be slippy. Not exactly formula you want for stoppage if you want to harness the fluidity of air to aid performance.

I hope this is the Scion you're talking about? http://image.motortrend.com/f/motors...g-scion-tc.jpg

The difference is that the front wing is high enough that it doesn't really affect the air around the body of the car.

The flaps on the Pagani will have high pressure in front of the flap, low pressure behind the flap. The low pressure behind the flap probably more or less cancels out the high pressure ahead of the flap. If you just have a flap like that in a free stream, the (negative) lift to drag ratio is still going to be very very bad, because most of the air is going to go around the side of the flap. There's nothing wrong with producing drag like that though, it just produces a yaw force, and it won't help balance the car as far as side to side weight transfer goes. The rear flap may do a little more because it doesn't influence airflow over the body.

[WingsofWar]

Originally Posted by serialk11r

I hope this is the Scion you're talking about? http://image.motortrend.com/f/motors...g-scion-tc.jpgThe difference is that the front wing is high enough that it doesn't really affect the air around the body of the car.

I just said that;

....aids braking, while aiding downforce depending on the situation, but never offers low pressure areas to the car's forward body because its completely detached from the main air stream

of course you cant speed up air velocity using low pressure waves without an attachment.

The flaps on the Pagani will have high pressure in front of the flap, low pressure behind the flap. The low pressure behind the flap probably more or less cancels out the high pressure ahead of the flap.

low pressure behind the flap means nothing because your decelerating an object in motion. You cant just cancel airflow around an object in motion, and suddenly air molecules travel at the same rate as the object in motion. aka 0 drag.

If you just have a flap like that in a free stream, the (negative) lift to drag ratio is still going to be very very bad, because most of the air is going to go around the side of the flap.

We are not in a free stream, the aerodynamic properties of earth surface with ground effects do not share the same principles as streamline aerodynamics because the road surface has its own boundary layer, which changes as objects move through its surface.

Negative lift for vehicles is always in the form of detachment and is never induced, which also cannot be achieved without a boundary layer which happens AFTER it has attached to a surface. UNLIKE airfoils on planes which is induced lift, based on surface attack angles. Meaning a Box with a flat surface hitting wall of air is not lift, its just drag...simple air Resistance.

Now look at the attack angle of the forward flaps on the Pagani, its at a insane negative degree angle which is used for downforce, or (airbrakes) for free streamed objects.

"Air brakes differ from spoilers in that air brakes are designed to increase drag while making little change to lift, whereas spoilers reduce the lift-to-drag ratio.." ~ Wikipedia

There's nothing wrong with producing drag like that though, it just produces a yaw force, and it won't help balance the car as far as side to side weight transfer goes.

Right, there is nothing wrong with producing drag appropriately, but I never said anything about weigh transfer, yaw induced by air stream pressure (AKA drag for vehicles) forces an object in motion to change direction accordingly. Meaning those flaps ARE changing the way air moves BEFORE the object reaches said stream of air, and a vehicle that moves through 2 axis of atmosphere, (vs 1 axis for flight) allows the air pressure, air speed, and drag to be modulated, meaning the downforce is actively changing.

The rear flap may do a little more because it doesn't influence airflow over the body.

actually it does, when you have a high pressure surface area in the rear, which is caused by a negative attack angle spoiler, which increases drag, which induces downforce. what do you think is happening to the low pressure air stream before it hits the spoiler? the air slows down. When air slows down on a surface (like the roof or the doors glass windows) that is aerodynamically slick and should produce good air velocity. There is friction. and that increase in friction forces the entire body of the vehicle to also slow like trying to move through a spider web.

But wait! the flaps are going down to a near 0 attack angle, this allows the high pressure area to disappear, we induce less drag, promote no more downforce, but that stream of air around the roof and door glass windows is not slowing down, no sir! now that it can speed through its low pressure, high velocity surface. No friction here! we can increase vehicle speed quicker without a spoiler.

also...
big problem with CFD and wind tunnel testing for vehicles...it doesn't take into account that a vehicles surface can move through 2 axis of air as it goes through a road course. Ever seen CFD of a drift car going through a corner? its a numerical nightmare.

[serialk11r]

Okay okay let's just clear a few things up.

Yes there is technically ground effect, but that wasn't the point. The wing on that tC is high enough that it is getting air that is mostly not disturbing the rest of the airflow. Yes it does change the airflow around the car, but not as much as it does on the Pagani, where the wake of the front flaps is more or less directly over the car's body.

Airfoils do not always rely on redirecting the air to generate lift. They attempt to pass more air over one side to create a difference in velocity, and ideally have zero drag. If you give it an angle of attack, then it's got induced drag because the lift vector now has a forward/backward component. On cars they often are given a high angle of attack because cars don't have enough space to fit large wings.

The Pagani flaps are by default stalled: no air can pass underneath them. They are too narrow to produce meaningful downforce even in the absence of the rest of the car body. You're right about the rear flaps, when they are raised the pressure of the air in front of them increases. However they still have the problem of having that big gap between the 2 flaps for air to pass through.

Because of these reasons, I'm saying those flaps essentially serve as airbrakes. Airbrakes can influence the weight distribution of the car since they apply a torque to the body (McLaren uses the airbrake not only to brake, but to increase weight on the rear wheels and improve the balance), but it's not as effective as using a device that produces really meaningful downforce (aka, producing significant net downforce as well as changing weight distribution).

[WingsofWar]

Originally Posted by serialk11r

Okay okay let's just clear a few things up.

Yes there is technically ground effect, but that wasn't the point. The wing on that tC is high enough that it is getting air that is mostly not disturbing the rest of the airflow. Yes it does change the airflow around the car, but not as much as it does on the Pagani, where the wake of the front flaps is more or less directly over the car's body.

I agreed with you two posts ago already, don't need to bring it up

Airfoils do not always rely on redirecting the air to generate lift. They attempt to pass more air over one side to create a difference in velocity, and ideally have zero drag.

Airfoils for planes always have lift, when they pass more air over to one side to make the difference in velocity..its still making lift. Impossible to have zero drag unless you make the surrounding fluid the same speed as the object in motions or you move through space which has no fluid to move through. Reynolds Numbers on fluid and viscosity works against your theory on zero drag. Please Read D'Alembert's Paradox if you want to try to prove that an object that moves through fluid (like air) can cancel the speed in which air flows around it by means of shape....

If you give it an angle of attack, then it's got induced drag because the lift vector now has a forward/backward component. On cars they often are given a high angle of attack because cars don't have enough space to fit large wings.

Airfoils don't actively induce drag, and lift vector is perpendicular to object direction...there is no forward backwards component..thats parallel, which is drag. Cars don't need large wings because the shape of a car is already aerodynamically cursed before you add ground effects.

The Pagani flaps are by default stalled: no air can pass underneath them. They are too narrow to produce meaningful downforce even in the absence of the rest of the car body.

they are not stalled..



and the forward flaps are attached to brackets that are bolted directly to the frame. Not the car body.

You're right about the rear flaps, when they are raised the pressure of the air in front of them increases. However they still have the problem of having that big gap between the 2 flaps for air to pass through.

Because of these reasons, I'm saying those flaps essentially serve as airbrakes. Airbrakes can influence the weight distribution of the car since they apply a torque to the body (McLaren uses the airbrake not only to brake, but to increase weight on the rear wheels and improve the balance), but it's not as effective as using a device that produces really meaningful downforce (aka, producing significant net downforce as well as changing weight distribution).

Thanks sorry i brought you into this long winded discussion..i was just arguing that the active aero does give focused downforce (especially up front). When you said you didn't think it did any meaningful function.

The Pagani Huayra is different from its predecessor in that it incorporates active aerodynamics.[3] It is capable of changing the height of the front from the ground and independently operating four flaps placed at the rear and front of the car.[3] The behavior of the flaps is managed by a dedicated control unit that is fed information from systems such as the ABS and ECU, which pass on information about the car's speed, yaw rate, lateral acceleration, steering angle and throttle position.[7] This is intended to achieve minimal drag coefficient or maximum downforce depending on the situation.[3] The Huayra's designer Horacio Pagani states that it has a variable drag coefficient of between .31 to .37.[8] The system also prevents excess body roll in the corners by raising the "inside" flaps (i.e. the left ones in a left-handed corner and vice-versa), increasing the downforce on that side of the car. The rear flaps also act as an airbrake. Under hard braking, both the front suspension and the two rear flaps are raised to counteract weight transfer to the front wheels and keep the whole car very stable, for instance when entering a corner.[7] Air from the radiator is extracted through an arch in the bonnet at an angle that is designed not to affect the streamline around the body. The side air intakes behind the front wheels create a low pressure zone, resulting in downforce.

[serialk11r]

Oh snap. Flaps in front open to vent. That would help things out some.

The rear flaps don't look like they have that effect since there isn't any extra air to evacuate from the engine compartment, but again rear airbrake will increase pressure over the body of the car so it's somewhat useful.

I'm still not a huge fan of the flaps, they are still kind of glorified airbrakes. They might increase downforce, but I'm pretty sure you can come up with something much better than that. With that level of complexity, you could be using some very elaborate ducting to control airflow under the car or something. But hey, they look pretty cool moving around so what the hell.

[ZetaVI]

The 86 will be on episode 3.

[Purdue FR-S]

AM I THE ONLY ONE AROUND HERE




That thinks this season is sort of sub-par? We're two episodes in, and while I've enjoyed them a lot I just don't seem to get as many laughs/enjoyment out of it as I used to.

Thoughts, opinions?

[mit_peid]

same here... can't wait!

[Rampage]

Originally Posted by Purdue FR-S

[B]
That thinks this season is sort of sub-par? We're two episodes in, and while I've enjoyed them a lot I just don't seem to get as many laughs/enjoyment out of it as I used to.

Thoughts, opinions?

Maybe you are growing up and outgrowing the sophomoric humor?