Legal ground effect?

[manchild]

I was wondering about allowed amount of flexing of floor panel and came upon this idea…

Imagine upper plane of that triangle overhang of floor panel in front of the sidepods shaped as wing to generate upforce. Now, if the allowed amount of flexing is significant and this would lead to generating of upforce strong enough to flex the panel upwards it would than enable the unthinkable – legal ground effect!

Not only that, but if these overhangs are increased all the way as much as the reg. allow that would also reduce overall drag since less air would enter the sidepods at high speeds.

Here is the “animation” showing the principle of idea:

[RH1300S]

I suppose the first response has to be that there is a flat bottomed rule and rules about how much deflection is allowed on aero surfaces.

The cars already use ground effect (I know you know that BTW ). It looks to me like you are trying to form the front part of a venturi, but surely without side skirts this idea is pretty redundant. I understood that flat bottomed cars pulled air under the car from the sides not just the front, this air is then accelerated across the underfloor by the diffuser and wing working together. I.e. given the lack of side skirts they can already get enough airflow to the underside, the problem is placing the centre of pressure and getting enough extractor effect from the arse end of the car to speed it through.

[manchild]

Yeah, I know about the current ground effect but I was thinking about that nice, old late '70s early '80 ground effect

I had upforce-downforce relation in consideration and I thought that loss by upforce necessary to cause flexing wouldn't be a problem since downforce gained by flexing/flow under sidepod would be much greater.

There is also question what would the situation be if that upper shape that should cause flexing is designed in a way that once it reaches it maximum position it does not generate upforce? I was thinking that this flexing would be caused only partially by that wing shaped top end while the rest of the job could be done simply by pressure that would push the floor upwards and keep it there until the speed drops?

Perhaps I should have mention/inquire - would this flexing with more air below the sidepods be more likely efficient if the floor behind the sidepod is minimized so that rear end of the sidepod/car can enable sort of suction with greater "appetite" than what the inlet - max flexed front would be?

And let me mention, the flexing on the drawing is sooooooo much bigger than it actually could be, but making animation that would show several millimeters flexing in 1:25 ratio would be quite difficult

[manchild]

Would it be better if rear end of the bargeboard is connected with floor via rod? When the bargeboard flexes it would lift the front end of the floor panel upwards… There would be no upforce since top of that peak of floor panel would be flat….

[kilcoo316]

I wonder how it would affect the Cp position

[DaveKillens]

I'm sure this would fall into the category of a moveable aerodynamic device, which are very illegal in F1. This concept is similar to allowing the wing surfaces to flex back under high air pressures, thus giving lower downforce (and thus drag) at higher speeds.
To make it happen, you would first need a high pressure zone under the area, and a low pressure area above, to begin to flex the panel. I presume that the opposite exists, where the air under the panel is of a lower pressure than the top.
Lastly, this panel would have this device making higher downforce, and thus more drag, at high speeds, the opposite effect desired. At lower speeds, (in the corners where maximum downforce is appreciated) the panel would flex back straight, lowering downforce.

[kilcoo316]

Lastly, this panel would have this device making higher downforce, and thus more drag, at high speeds, the opposite effect desired. At lower speeds, (in the corners where maximum downforce is appreciated) the panel would flex back straight, lowering downforce.

Good point

[RH1300S]

The early '80's ground effect were venturi cars, they only really worked because they had skirts to close the venturi sides. The upcurved front formed the mouth of the venturi.

I think I'm right in saying you can't form a venturi without closing the sides to some degree, but you can achieve ground effect by accelerating the air across the underside of the car. If it's not a venturi, then it does not need a throat - so surely a generous radius to the floor edges would be equally good at allowing air to get under the car (if that's a good idea at all with a flat bottom?).

I am speculating here, but wouldn't a flat bottom work better if you could use the energy of the air that's going down the side of the car and trying to get underneath (assuming the diffuser is doing it's job) to work on surfaces just above the floor (i.e. like the highly sculpted side pods many cars have today)

[Apex]

Firstly i agree with Dave

What i dont understand is, why not mould it in the upward position if it was better?

[Guest]

I believe you are correct.
Physical skirts aren't allowed, but I believe that the sidepods are sculpted in such a manner as to have an effect on the flow of pressures along the side of the underbody tray. If very low pressure could be generated along the very bottom of the sidepod, then it would most probably assist in creating, or at least, mainting low pressure along the underbody.
Can anyone verify or disprove this assumption?

[kilcoo316]

You see the small mini wings ahead of the side-pods close to ground level, they used to be on the jordan and williams.



The wingtip vortice from these wings helps seal the sidepod underside from the air flowing down the sides of the car.

[Guest]

When talking about undercar downforce creation you want the least possible air going under the car and thus creating a low pressure zone. By increasing the relative height to the ground of the car's floor you would increase the air going underneath the car and thus lowering the downforce created. As someone said to raise the floor you would need a low preassure on top of the floor and high pressure beneath it which is the opposite of what happens in reality.

[manchild]

When talking about undercar downforce creation you want the least possible air going under the car and thus creating a low pressure zone. By increasing the relative height to the ground of the car's floor you would increase the air going underneath the car and thus lowering the downforce created. As someone said to raise the floor you would need a low preassure on top of the floor and high pressure beneath it which is the opposite of what happens in reality.

I don't get this... I mean I know that there are no skirts and that everything is based on diffuser nowadays but I don't understand your statement - "you want the least possible air going under the car and thus creating a low pressure zone"? Why are the noses raised than?

More air flowing underneath the car = lower pressure. Car’s bottom and track form Venturi tube and as the amount of air increases in the point where the car is closes to the ground. That point as the narrowest increases speed of air and low pressure.

Nose is the front end of Venturi tube and the diffuser rear end of Venturi tube while wooden plank and floor (all the way) are the mid section with lowest pressure/highest air speed, right?

[DaveKillens]

Don't confuse mass with velocity. The low pressure area is created by air velocity. In fact, the ideal underbody would have a perfect vacuum between the car body and road surface.
I assume the nose is high to allow a controlled amount of air to enter the front of the underbody. But I seriously doubt it is there in an attempt to ram as much air as possible under the undertray. That would create a high pressure area, regardless of how much velocity you can impart to it.

[RH1300S]

Why are the noses raised than?

The raised nose does not necessarily send more air under the flat bottom - to look at it, there is often a projecting shelf at the front of the floor I can visualise air forming high pressure on the top surface of this. Is'nt the high nose about managing air to the sidepod intakes and then around and over the sidepods (i.e. you get a cleaner flow into the intakes and also back to the ever important rear wing)?

More air flowing underneath the car = lower pressure. Car’s bottom and track form Venturi tube and as the amount of air increases in the point where the car is closes to the ground. That point as the narrowest increases speed of air and low pressure.

Nose is the front end of Venturi tube and the diffuser rear end of Venturi tube while wooden plank and floor (all the way) are the mid section with lowest pressure/highest air speed, right?

More air does not mean lower pressure, faster air does (EDIT: which is what Dave said - I was typing this while he posted!). Sending too much air under could easily slow it down surely?

I think it is best not to think of a venturi tube in this situation - the air flows in at the front in the direction of travel, but it's easy to visualise that a lot of the air will be sucked in at the sides at 45deg (ish) to the direction of travel. I.e. it's not the forward speed of the car pushing air under it, but the energy of the diffuser & wing sucking air out from underneath which causes a pressure drop, which the air at the front & sides tries to fill - to me the logical conclusion to that statement is that you don't want to encourage air in as this is only headed in that direction in trying to balance the pressure.

Or, to put it another way, you want more air out than in..........

Surely with a flat bottom car all you really want to do is watch the radii of the edges to help the transition of air going under the floor (i.e. maybe you don't want sharp edges which might cause separation and are perhaps more pitch sensitive.