Landracing Forum
Bonneville Salt Flats Discussion => SCTA Rule Questions => Topic started by: javajoe79 on December 23, 2015, 11:00:08 AM
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So in the rule book, approach #1, you are allowed to fill the horizontal gap between the body and the leading edge of the spoiler up to the centerline of the rear axle. On the firebird that space is nothing in the middle then extends all the way forward to where the stock wing ends. I am assuming that would be fine. I can't find any pictures of the same car with a spoiler like that. Anyone know of any?
Our car has this style rear wing. (http://i873.photobucket.com/albums/ab300/Mastertomos/33643412853354971039IM103565x421_A562x421_zps3f29d48f.jpg)
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Chris, I don't know if this answers your question but here are a couple of pics I got a few years ago of the MacDonald and Pitts 300+ 1999 Firebird.
Looks to be the same factory spoiler that you have so it probably would be sufficient.
(http://i67.tinypic.com/rr2jvm.jpg)
(http://i63.tinypic.com/2cxaufd.jpg)
Hope this helps,
Gregg
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If the spoiler is OEM, unmodified, it will be OK from Production to Altered classes. One caveat, is that a SPOILER has a single aero surface, air going under the rear lip, even if OEM, is considered a wing and not allowed in some classes.
Check with your committee chairman if this is a SCTA question for El Mirage or the salt. If for another venue, never mind.
DW
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Yes it's the same as that car above. Couldn't remember if that car had a spoiler on it or not. What I am talking about is adding a sheet metal spoiler as described in the book 4.CC.8 approach 1 Figure 9
Was hoping for another same year firebird with a fabricated spoiler like that. Anyway I will run it by Lefevers.
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I'd think any deviation from what is there stock would put you complying with the rule book's definition of a spoiler and where it can and can't be.
Personally in a lot of cases where you don't need the downforce of one (which usually also is accompanied by more drag) the main benefit of a spoiler is that you can then add spill plates and those I would make to the maximum dimensions of the rule book. Also where the spoiler is located will let you make them larger in some cases and still be within the rules. The spill plates are going to add to your center of pressure and can be actually added in twice if you use this method of determining your cars center of pressure...
http://1fatgmc.com/car/14-Hooley/14%20-%20hooley-construction-2014-2.html
Getting the CP location as far reward of the CG can pay big dividends in having a car that isn't inclined to spin. In Hooley's case the spoiler had been there to gain the advantage of the increased CP the spill plates give the car.
(http://purplesagetradingpost.com/sumner/Hooley%202013/wing--87.jpg)
Now it is the wing that allows us to really improve the CP by allowing the verticals. As time goes on we will try and use the wing also more and more for downforce as we are about the limits of adding weight to the car,
Sumner
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Great info as usual Sumner. I don't think we will need much downforce as this thing will be heavy!! I will be maximizing spill plate size. Spoiler will be adjustable and with gurney flap option. Also would like it to freely flip up in case of a spin to help keep the car on the ground :cheers:
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.. Also would like it to freely flip up in case of a spin to help keep the car on the ground :cheers:
(http://purplesagetradingpost.com/sumner/Hooley%202013/wing--84.jpg)
Consider putting in a roof flap/flaps. You can see the one above that Hooley installed on the car.
Sumner
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We have a pair of flaps but there's really only room for one. So we will have that too.
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Chris:
I built one for gen two Camaro to what I think the maximum rules says. The spoiler can be set for +5, 0or -5 degrees. What I wanted was what Sumner said as much spill plate as possible. It has not passed tech but I think it will. I also wanted the deck lid to open with out a lot of trouble. There are 4 vertical stabilizer turn buckles and two spill plate turn buckles to brace and make sure they stay vertical.
BR
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That is what I am planning. Looks nice! Did you use 1/8" for the spill plates?
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Yes, the center plate is actually an Ed Quay piece that I shortened to meet the 10" chord limit. The side plates have tabs the mount on the underside of the trunk with .250" button heads on top of the deck. I used the old GM panel fitting to my advantage. Was able to adjust the trunk where the 1/8" spill plates fit in the gap. I have a drilled angle mounted underneath for a Gurney Flap if there is a need.
BR
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I found this pic of a spoiler for similar car. Thoughts?
(http://i292.photobucket.com/albums/mm17/chwdhw/Breaking%20Wind%20Firebird%20Build/90c701dffa54ff8c4a27373f7cce2686_3q8f.jpg) (http://s292.photobucket.com/user/chwdhw/media/Breaking%20Wind%20Firebird%20Build/90c701dffa54ff8c4a27373f7cce2686_3q8f.jpg.html)
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(https://scontent-dfw1-1.xx.fbcdn.net/hphotos-xfl1/t31.0-8/12307598_402275079968902_623935577447828193_o.jpg)
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....What I wanted was what Sumner said as much spill plate as possible..
(http://www.landracing.com/forum/index.php?action=dlattach;topic=15559.0;attach=53523;image)
Was there a reason you slopped the spill plates down? I think they could of been higher in the front giving more area that would help the CP.
(https://scontent-dfw1-1.xx.fbcdn.net/hphotos-xfl1/t31.0-8/12307598_402275079968902_623935577447828193_o.jpg)
The spill plates on the car above could of also been made larger. It is tempting to change the shape to make them more pleasing to the eye but I'd make them as large as the rules allow and the hell with looks,
Sumner
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I found this pic of a spoiler for similar car. Thoughts?
(http://i292.photobucket.com/albums/mm17/chwdhw/Breaking%20Wind%20Firebird%20Build/90c701dffa54ff8c4a27373f7cce2686_3q8f.jpg) (http://s292.photobucket.com/user/chwdhw/media/Breaking%20Wind%20Firebird%20Build/90c701dffa54ff8c4a27373f7cce2686_3q8f.jpg.html)
Thinking sort of like this but hinged at the point where the stock spoiler ends. I have an email in with Lefevers also. Pretty sure how I have it envisioned in my head will work well and be legal. I agree with Sumner on keeping the spill plates at max size and I think they will also look fine on this car. At 300 mph who cares what the spill plates look like?
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....What I wanted was what Sumner said as much spill plate as possible..
(http://www.landracing.com/forum/index.php?action=dlattach;topic=15559.0;attach=53523;image)
Was there a reason you slopped the spill plates down? I think they could of been higher in the front giving more area that would help the CP.
(https://scontent-dfw1-1.xx.fbcdn.net/hphotos-xfl1/t31.0-8/12307598_402275079968902_623935577447828193_o.jpg)
The spill plates on the car above could of also been made larger. It is tempting to change the shape to make them more pleasing to the eye but I'd make them as large as the rules allow and the hell with looks,
Sumner
Sum:
They are level horizontally front to back, it's just the angle of the shot. here is another shot of the finished spoiler with the car level on jack stands.
BR
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at 300 it is REAL nice when the car goes where you are wishing it to!
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Here are two photos of Rex Svoboda's beautiful McLaren M6GT showing airfoil & spill plates. He said the car was very stable at 200mph.
Regards, Neil Tucson, AZ
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I bet that Mclaren is nailed down at 200mph!!
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....They are level horizontally front to back, it's just the angle of the shot.
I was wondering if that might of been the case. They look good,
Sum
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One thing about having the spill plate being triangular in shape similar to the McLaren that Neil provided is that this shape when it become side ways to the air flow, as in the. rear end getting loose, it will generate a huge amount of aero force that opposes the spin force of the car. The "delta" shape is extremely efficient and works by generating a very strong vortex on the opposite side of the spill plate that generates the differential pressure on the plate that opposes the spin forces.
Rex
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The Mclaren being mid engine had a rear bias CG so we had to add vertical side surface to chase the CP rearward and keep the car stable at speed. The 'wing' was more for structural strength as down force which it turned out we did not need at Bonneville. The wing helps a bit when running the Silver State road racing events but with only 450 available engine hp we had enough traction on the salt without the help of a wing. The car was very stable on the salt and easy to drive even in heavy cross wind gusts. I have Fond memories of looking out the big picture window going down track on a sunny Bonneville morning.
It's all about the air
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Joe-
We built ours ('98 Camaro) using the same approach (#1) you're considering (1/8" aluminum on the spill plates) but without the adjustable "flap". It certainly helped with down force; probably TOO much for a mile car. With the speeds you'll be approaching with that car (and Production being out of the question due to the turbos), you may as well build one large enough to help your down force and stability. Just my .02.
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If you mounted your roof flaps at 45 deg to centerline you should have room for two shouldn't you? that way they come out before you go 180 rotation.
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If you mounted your roof flaps at 45 deg to centerline you should have room for two shouldn't you? that way they come out before you go 180 rotation.
Maybe but probably not at their current size. The roof is just too narrow and curved so they also don't fit the profile.
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Some where on my truck build I have photos of my NASCAR type flaps.
I do know some of the teams actually sell roof flaps with hinges and tethers.
Check it out. You might find a solution. :cheers:
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Like these. http://www.ebay.com/itm/Nascar-arca-scca-roof-flaps-complete-with-cables-/111711489092?hash=item1a02860c44:g:esAAAOSw~gRVmYG7&vxp=mtr
Doug :cheers: :cheers: :cheers:
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Good deal at $69. :cheers:
Nice one Doug,
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Muscle Motorsports in Huntersville/Mooresville, NC has roof flaps (and a lot more
NASCAR parts). The late Bob Gribbel (sp?) put together a really nice resource for
LSR guys; always worth a call if you need something hard to find.
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We have exactly what is in that link ^^ They're huge
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Ok so I am making progress here and was wondering about support struts between the spill plate upper edge and the body and or rear window and or filler plate in front the hinge pictured here. Probably just some 3/16" stainless rod to keep the spill plates from flapping.
(https://scontent-atl3-1.xx.fbcdn.net/v/t1.0-9/13428655_892149047561657_59596474732886845_n.jpg?oh=565166f7631add661e84e1e067ebe017&oe=57C25CBF)
Here is the side view. The spill plates will be at maximum dimensions allowed.
(https://scontent-atl3-1.xx.fbcdn.net/v/t1.0-9/13435525_892149037561658_6211879364381124425_n.jpg?oh=8ed4d2153e6cfe1194c4cab63b111f55&oe=57CF8495)
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If you do a strut rod you might want to look at shaping it for minimum drag, and elliptical shape has something like 1/10th the drag of a comparable round rod.
Probably could shape your own strut rod with a little machine time or sander time.
http://faculty.dwc.edu/sadraey/Chapter%203.%20Drag%20Force%20and%20its%20Coefficient.pdf
A little google searching on aircraft wing struts will probably find an appropriately shaped cover for your strut.
Something like this:
http://www.aircraftspruce.com/catalog/lgpages/de-struts-strutfittings.php?
http://www.ultralightnews.ca/streamlinedfairings/1.html
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Agreed but these won't be large at all. Any of those aero tubes are way bigger than a piece of 3/16" stainless rod. I also worry about the struts being considered streamlining as per 4.CC and therefore illegal