it is simple....
the antenna spiral creates a vortex in a manner such that it creates a low
pressure around the front of the vehicle. this low pressure effect is like
the vehicle always driving or being pulled into a vacuum. And this take
less gas to move the vehicle along and is similar to a draft when one
follows real close behind a big truck on the highway.
If it was that simple to increase gas mileage, why don't cars have several
of these. And if a small piece of wire has that much effect on a large
vehicle, why are airplane wings so big?
If the vaccuum I could create behind my motorcycle is to be looked at, I
would pull a tractor trailer off the road when I passed by.
Sounds like a lot of horse manure to me. An AWFUL LOT of horse manure.
I am sure there is a valid reason for the spiral, but I don't think it has
anything to do with gas mileage. If it did, all the manufacturers would be
using it. And you would find someone on the tube seling them and making a
mint. Have you seen that? I didn't think so!!
The spiral reduces noise created by air rushing across it. If you
don't belive it, run a piece of tape lengthwise to the antenna and
drive at 65 mph. It will have considerable noise.
STOVEBOLT (Nickname for 1930's Chevy)
On Mon, 31 Oct 2005 02:19:41 GMT, "Yammie"
Mitsu huh. Figures ...
I've got a bunch of the others around here as spares. They are all
ground. The easy way to tell is to look at the base area, the grind
stops about an inch above the adapter. On average we coated 30,000 a day
for each of the big three. Hated the damn things because they were
racked 20 per row on a 3 row rack. You had to get between the rows and
coat the adapters, then down the shafts, then spin them while coating
from the outside. Too much powder and you hid the details and had a
"drip" on the end. Not enough and you got textured finish.
"Steve Mackie" < firstname.lastname@example.org> wrote in message
Mine is also a wire wrap, just went down and looked at it. I took a picture,
but my camera sucks so it didn't take well. I can tell it's a wire wrap
because it's starting to seperate in one spot and in another there is a kink
in the wire. I also looked at the two cars parked next to me, a late model
Buick and a late 90's Caravan. The Caravan appeared to be a wire as well and
the Buick's was identical to mine. You really can't get much more common
than a mid-90's W-Body GM, so it's safe to say there is A LOT of wire
wrapped antennas "whipping in the wind."
And I believe the ones top-center on the window are there as a
sunscreen, since you can't get a visor over there. You don't often
need to look through that portion of the window, so they block out the
The spiral is to reduce wind noise???? Reducing the smoothness of a
wind-exposed surface hardly reduces the wind noise---in fact it would have
the opposite effect.
The spiral is indeed for the purpose of increasing the effective length of
the antenna. It's a common practice to use a coil to reduce the physical
size of an antenna without decreasing its effective length.
As for the dots, I have no idea. My guess would be to act as a sunscreen.
sean email@example.com (Sean Elkins) wrote:
GULP--the sound of me eating my words. Looks like I was wrong about the
wind noise, although in my meager defense that does seem counter-intuitive
that roughing up the surface would cut wind noise. I thought the more
streamlined an object the less air it would displace?
From an Engineering stand point.... The Spiral wrap induces Eddy
which reduces the wind drag force on the antenna to minimize
whipping action.... This and the German periscope spiral
are notorious educational discussions at Automotive Engr Seminars
in Detroit in the fall.
The spiral wrap on the car antenna is there to reduce wind drag &
stop antenna 'whip motion'. The German's used this feature on WW2
submarine periscopes to stabilize 'periscope viewing'. With the spiral
wrap, antennas could be made smaller diameter & still resist wind/water
without bending nor vibrating much in the breeze.
Most of the above-mentioned apply, especially the eddy current and
vibration, but the primary purpose of the spiral is to
prevent/avoid wind resonance (re: Tacoma State Bridge). If you
have ever driven in sleet/rain and have the spiral-wound antenna
caked in ice, the antenna will vibrate, depending on our speed,
initially with one node, then two nodes, then three if you are
crazy enough to drive that fast in that weather.
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