Bodywork, Paint, Interior, Trim, & Wiring

discussions about bodywork, paint, interiors, trim, audio, electrical components, wiring, etc.

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roverman
Art Gertz
Winchester, CA.
(3006 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Floor pockets for seats
Posted by: roverman
Date: February 13, 2012 04:39PM

Is it possible correctly shaped "pockets" for seats, could add aero downforce,(inverted wing) ? Good news is RX 7 rear control arms will clear seat pockets easier than JH trailing arms.The more things change- more things need changing. Cheers, roverman.


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1087 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: Floor pockets for seats
Posted by: ex-tyke
Date: February 13, 2012 04:53PM

Would probably add to drag rather than provide downforce -
.......if it worked that way, the BIg Boys would have picked up on it!


roverman
Art Gertz
Winchester, CA.
(3006 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Floor pockets for seats
Posted by: roverman
Date: February 13, 2012 05:22PM

"Some", Paul Newman/ others, of the big boys used gas tanks shaped that way, for same reasons. I need the pockets-regardless, so why not more aero ? I will be using simlar shape floor, leading to rear radiator. Most aero down-force devices add drag, as a necessary evil. Cheers, roverman.



Edited 1 time(s). Last edit at 02/13/2012 07:25PM by roverman.


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1087 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: Floor pockets for seats
Posted by: ex-tyke
Date: February 13, 2012 05:37PM

You'd be better off trying to exclude all under chassis air......think NASCAR!
Guess it all depends on the final useage of the vehicle whether downforce (aero drag) takes precedence over top speed and fuel economy. Like you said, most aero devices contribute to drag.


Bill Young
Bill Young
Kansas City, MO
(1337 posts)

Registered:
10/23/2007 09:23AM

Main British Car:
'73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep

authors avatar
Re: Floor pockets for seats
Posted by: Bill Young
Date: February 13, 2012 05:54PM

Art, I don't get the "inverted wing" idea at all since to get the wing effect you basically need air flowing over the top and bottom of the surface. Can't fault you on reducing drag though on anything that is in the air stream. Good old boys such as Smokey Unick were doing that for years in NASCAR until the rule makers started to put an end to it with the body templates. If you have to put somehting on the car anyway, then it might as well be as light as possible and as aerodynamic as possible anyway. You really could take it to extremems with wing shaped lower a arms and even a wing shaped cover for the axle housings if you were running a live axle.


Moderator
Curtis Jacobson
Portland Oregon
(4414 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: Floor pockets for seats
Posted by: Moderator
Date: February 13, 2012 06:13PM

A pocket might be a good idea if it allows you to lower the driver's mass. In an open car, it might allow you to get his helmet down out of the airflow.

Even if a floor pocket were somehow shaped like a wing, it wouldn't function as a wing because it's in turbulent airflow. IMHO, the really important thing is to minimize airflow under the car by (a) getting the car as low as feasible and by (b) getting your air dam / skirt as close to the ground as possible, and by (c) shaping the air dam in a way that discourages air from flowing through what little gap is left. If the rules allow, you'll probably end up with something like this:

aero.jpg

If you think of the whole area under the car as having one average air pressure, and the whole area over the car as having another (higher) air pressure, then you can see that it's quite feasible to make the whole car behave as a "wing" with downforce as the net effect.


roverman
Art Gertz
Winchester, CA.
(3006 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Floor pockets for seats
Posted by: roverman
Date: February 13, 2012 07:20PM

I wish I could post a pic' of bottom of Ferarri 355., similar to what I'm after with AC 6.1. This being a road going car, articulated side skirts/front dam = non viable. I do hope to "steer" the splitter, mounted to bottom of front air dam. In the real world, this means getting considerable air under car and the best practicle way to use that air. Bill, when I say inverted wing, the bottom of this car is bottom half of a crude wing, that unfortunately creates lift at speed. "If" you can get air under car to speed up, without separating, it will contribute "some" down-force, ie. tunnels, diffusers or venturis. Perhaps Dave Craddock can weigh-in here ? Onward, roverman.



BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5853 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Floor pockets for seats
Posted by: BlownMGB-V8
Date: February 13, 2012 09:33PM

The concept does have some merit. Were you planning to add a full belly pan?

In the conventional airfoil the larger curvature and longer path over the top causes the air to speed up which lowers the unit pressure. However the air over the car body already follows a much longer path than you can hope to create under the car, which is the cause of the basic high speed lift that is so common. Obviously turbulence and laminar flow both play a part. If flow under the car can be kept laminar it will reduce unit pressure. Also making use of the choke points, ie, directly under the seat pockets as venturis will accelerate airflow in that area, further reducing unit pressure. This may be enough to get you what you want. Proper throat area control coming off the venturi can create suction which will help pull the car down towards the road. But, the balance may be off where you have the venturi halfway down the car rather than nearer the front. Mind you, without the help of side skirts it'll be difficult to get a great deal of effect.

Now on the top, anything that causes turbulent flow will kill lift. It will also cause drag but if a smooth envelope can be maintained enclosing the turbulent areas it should be possible to lessen the drag while still having the benefits of the turbulence. Or... you could just build an aeroplane.

Jim


Bill Young
Bill Young
Kansas City, MO
(1337 posts)

Registered:
10/23/2007 09:23AM

Main British Car:
'73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep

authors avatar
Re: Floor pockets for seats
Posted by: Bill Young
Date: February 13, 2012 11:29PM

For production cars perhaps Lotus had the cleanest bottom surfaces, with many having almost a completley smooth floor pan in fiberglass. I know that my Europa is pretty slick in the wind with only a small duck tail at the rear and oringally a fairly small chin spoiler up front. My car has a larger front spoiler and sticks to the road quite well for a car with a very light front end. Of course I'm not going nearly as fast as you plan on, but I think Jim's idea of a belly pan would be well worth considering and just use some small aero devices up top to spoil the lift a bit.
side view small.jpg


roverman
Art Gertz
Winchester, CA.
(3006 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Floor pockets for seats with belly pan
Posted by: roverman
Date: February 14, 2012 11:41AM

As mentioned in my JH post. Virtually all of our street use cars and most race cars, in this forum, have more aero lift than down-force, ie. a crude lift wing. When we say down-force, we're trying to counter lift with whatever means is practical. Not having a wind tunnel at my disposal, or the resources of a car manufacturer, this is seat-of-pants developement, at best. Jim B., I'm "kinda" building an aeroplane, jus' the landing gear will always be deployed/lol. Onward, roverman.



Edited 1 time(s). Last edit at 02/14/2012 07:05PM by roverman.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5853 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Floor pockets for seats
Posted by: BlownMGB-V8
Date: February 14, 2012 09:13PM

Well, just try to keep the dirty side down Art.

Jim


Jim Stabe
Jim Stabe
San Diego, Ca
(739 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

authors avatar
Re: Floor pockets for seats
Posted by: Jim Stabe
Date: July 25, 2012 12:41PM

Art

I just stumbled across this thread. I agree with Jim that this idea may have merit if you have smoothed up the rest of the underside to enable laminar flow between the car and the ground. It's pretty difficult to do without diverting the radiator exhaust somewhere else because that air is pretty turbulent after it goes through the radiator and bounces off all the engine bits before exiting out the bottom. The front suspension arms and the rotating front wheels don't help either. A front air dam/splitter do a good job of increasing downforce in the front by creating a low pressure area directly behind the dam and a shelf on top of the splitter for the high pressure stagnated air in front of the dam to act on. However, by minimizing the number of air molecules that get under the car the air dam would also reduce the effectiveness of the aero floor pockets and any other aero improvements you make to the bottom of the car. The F1 cars that used the inverted wing bottom contours so successfully encouraged high airflow under the car but they had no obstructions to disturb the laminar flow.


Preform Resources
Dave Craddock
Redford,Michigan
(359 posts)

Registered:
12/20/2008 05:46PM

Main British Car:
72 MGB V6 3.4

Re: Floor pockets for seats
Posted by: Preform Resources
Date: July 25, 2012 02:44PM

Yes a clean underside is better, seat pans while lowering the c/g will disturb the air under the car, since most production type cars have openings for engine/trans, rear axle etc that disturb the air anyway seat pans will probably not hurt much. the NASCAR boys have cleaned up their undersides a lot and the run the trunk floor at an angle up to the quasi rear bumper,
creating a dffuser with out the sides, If they were allowed to drop the sides down (there by creating a true diffuser) they would generate a lot of down force. On LMP, DSR, Daytona prototypes the center of pressure changes depending on where the diffuser
begins, the farther forward the more centered the CP. It's all a matter of using the Bernoulli theory, creating a vacuum under the car, the diffuser allows the air to return to normal speed. Formula one cars have many mandates dictating what is legal, still they useevery surface to aero advantage, bluff body cars like Nascar, SCCA production,etc can't take advantage largely because of rule restrictions, so front splitters and deck spoilers trim out the top air and can be used to balance the car ,,somewhat.
ground effects aero dynamics is a black art and science and expensive to prove out.
Dave


Jim Stabe
Jim Stabe
San Diego, Ca
(739 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

authors avatar
Re: Floor pockets for seats
Posted by: Jim Stabe
Date: July 25, 2012 03:27PM

Dave

I was assuming that Art was going to have the floor pan pockets tapering gradually front to rear starting just aft of the front wheel arch and ending right before the rear wheel arch to create a venturii right under the seat. If he did that the pockets by themselves wouldn't disturb the air much. They would only be effective though if the rest of the underside was cleaned up and you weren't dumping a bunch of dirty air out the bottom from the engine compartment and you allowed sufficient airflow under the car.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5853 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Floor pockets for seats
Posted by: BlownMGB-V8
Date: July 25, 2012 05:06PM

One of the reasons F1 venturi effects work so well is because the engine is in the rear. But I believe Art said he was putting the radiator in the back so that would really help clean up the airflow and make it a lot easier to seal the bottom of the car. Even so you do not have the advantage of an inverted wing at the front and typically it is more of an issue to develop front downforce than rear where you can always make the wing more aggressive. The vacuum developed by the venturi effect will be to the rear of the seat pocket and will develop more downforce at the rear of the car. This may be a problem.

Jim



roverman
Art Gertz
Winchester, CA.
(3006 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Floor pockets for seats, update 7/26
Posted by: roverman
Date: July 26, 2012 04:14PM

Car will have nearly full belly pan. Front air intake for oil cooler only,(tested for effectiveness). Approx. 2,600 cfm of fan flow through rear radiator,(NO snow moblile engine) ! Most aero enhancement will be trial and error with "Magnehelic". Hi speed trivial pursuit, will be easier with Maxton-like TR7-8. Thanks, roverman.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5853 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Floor pockets for seats
Posted by: BlownMGB-V8
Date: July 26, 2012 09:07PM

Is it true that Jim Hall's creation would stick to the ceiling with no forward motion? Now THAT I would like to see.

Jim


roverman
Art Gertz
Winchester, CA.
(3006 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Floor pockets for seats, more fan-more fan !
Posted by: roverman
Date: August 01, 2012 12:27PM

According to Jim S. ,oem has 4-4.5k cfm., per fan. That really sucks, in a good way ! Would (2) make this a hybrid fan powered car ? "Maybe those golf ball dibits on bottom of belly pan ? Wheeler Vortex Generators, just over rear window. Tunable/steered spliter at front, for downforce. Dump ZO6 exhaust into negative pressure, at rear "Kamm" area. Onward, roverman.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5853 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Floor pockets for seats
Posted by: BlownMGB-V8
Date: August 01, 2012 02:46PM

I know, with your radiator in the rear use a massively oversized fan and pull the cooling air from under the car. Then you just need some skirts to restrict the air getting in and you have a Hoovermobile. Which you can then drive on the ceiling. ;-) (sounds familiar somehow...)

Jim


roverman
Art Gertz
Winchester, CA.
(3006 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Floor pockets for seats
Posted by: roverman
Date: August 01, 2012 03:01PM

Idea is to pull air through belly pan and floor,in this manner, ride height does little to affect downforce. This should work somewhat like 355 Ferarri, only maybe $200k-less. Onward, roverman.
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