Downforce

Archives of Posts to the NZ MX5 List back in 2003
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EricW
See my 5 and raise you.
See my 5 and raise you.
Posts: 95
Joined: Wed May 24, 2006 7:07 pm
Location: Whangaparaoa

Downforce

Post by EricW » Thu Sep 04, 2003 8:29 am

Actually, thinking further about this, these spoilers are, as best I can
recall, set at a reasonable angle of attack. Suppose the wing was about as
efficient as that on a Piper Cherokee, (not a star amongst efficient
airfoils), that wing supports 2150 lbs at 61 knots (about 115 km/h) before
stalling. So, on a 136 sq ft wing, that is a wing loading of 15.8 lb/sqft.
Without measuring it, I guess a Mazda wing is about 4 ft by 6 inches, thus 2
sq ft. Assuming the other things are true, it is probably pushing down at
about 15 kilos at 115 km/h. Bear in mind that, unlike an aeroplane, the
angle of attack is constant, thus downforce will increase or decrease only
with the square of speed, twice the speed = four times the force. At 160
km/h of racing speed you would have about 30 kilos of downforce.

The downside to this is that drag also increases with the square of speed,
the drag produced by this wing, (and you cannot get lift without drag), is
four times as high at 100 km/h than it is at 50 km/h. So unless the
Lift/Drag ratio of these wings is fairly efficient you are probably chewing
a bit of gas to get a small amount of downforce.

But what the hell, they look good!

Eric

jeff

Downforce

Post by jeff » Thu Sep 04, 2003 9:24 am

"aerodramatics" I believe Bwob called it ;)

Jeff
resident miataforum parrot

--- Eric & Ann West <ericwest@internet.co.nz> wrote:
[...]

jeff

Downforce

Post by jeff » Thu Sep 04, 2003 9:24 am

"aerodramatics" I believe Bwob called it ;)

Jeff
resident miataforum parrot

--- Eric & Ann West <ericwest@internet.co.nz> wrote:
[...]

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