m21sniper

Exactly correct. Probably the easiest way to diminish a laser reflection is with a flat dark surface.(like a bra).

Get a laser pointer and aim it at a white wall, then something flat black. On the flat black surface it is literally 1000x dimmer than on a glossy white surface.

When we were trained to LAZE targets with the GV/LLD(aka "GLID") for laser guided 155mm Copperhead artillery strikes, we were taught to always LAZE on the most brightly painted/lightly colored portion of the target we could find.

Another effective way to greatly diminish a laser reflection is to aim a counter-light source at the laser emmiter, like an extremely intense IR flood for instance. If the IR flood is more intense than the laser beam, it will completely 'drown out' the laser beam reflection.

Ron_H

That is also very interesting.

bdstott

Hmmm,
Don't the brake lights on the newer Trail Blazers (amongs other cars) routinely set off Radar (laser) detectors?
How about mounting a string of them along the front airdam for a nice stealthy ricer look?

928SS

threads like this (and the speeding threads) just keep telling me to sell my shark before bad things happen. suppose I should be happy it won't start right now (poss. fuel pump -the only friggin thing I havn't replaced/upgraded)

old news: http://www.radarbusters.com/products/coatings/veil.asp it's anti laser gel. guess it's ok if you don't mind having a car that looks like it was used for a ky or afrosheen commercial (or "target practice" in a **** theater) hehehe.. yeccch!

the laser blinder looks pretty cool though. bout it for legal stuff, since lazer is ok to transmit/jam...

http://home.houston.rr.com/crxtreme/...adarjammer.htm shows how to "fix" a detector to make it a jammer - but iirc, it's a felony to transmit/jam radar in the US.... course, gang rape in the shower seems a bit harsh just for a "malfunctioning" radar dectector though...

could just use a beartracker / scanner... kinda legal if you are only using it to listen to the weather or news channels/not commit crimes I suppose...

I still think diplomatic immunity is your best bet, or having a daddy that is the govenor/mayor/police chief. I suppose simply not speeding would be the easy answer though. does make a good case for a boring hybrid or a limo (or a bus pass)

m21sniper

"http://home.houston.rr.com/crxtreme...radarjammer.htm shows how to "fix" a detector to make it a jammer - but iirc, it's a felony to transmit/jam radar in the US.... course, gang rape in the shower seems a bit harsh just for a "malfunctioning" radar dectector though..."

It is perfectly legal to have a RCS(radar cross section) so low you simply DON'T APPEAR on radar.

Seriously though, this thread was posted as lighthearted fun.

928SS

I was having fun! hehehe.

m21sniper

Mission accomplished then.

Nasty 928

OK, 1st - Its total bs about the color affecting radar reflection-see Myth Busters, they painted a car flat black and had it make several runs past 3 different radar guns, and every time it gave a reading.

2nd there are multiple bands of radar-
x band (old crap)10.475 to 10.575 gigahertz,
k band(1970s crap)24.0 to 24. 25 gigahertz spectrum,
ka band (late 80s) 33.4 to 36.0 gigahertz range,
POP and Instant -on
POP is not as common any more because cops cant lock on to individual targets( me ).
Instant-on- cops leave gun on stand-by and aim,squeeze trigger when they want to get a reading- becoming un-popular because they(cops) are lazy.

If you want a lazer jammer they do make them- BLINDER, Escort Shifter, and Beltronics LaserPro.
Laser jamming devices are not regulated by the FFC but by the FDA and there is no federal laws regarding the jamming of police laser guns.
*BUT some fun hating states have laws banning them* )Minnesota, Cali, Utah, are some.

RMR-rocky mountain radar makes lil things called Phantom, Phaser.. they suck, they DO NOT jam radar or laser and the dector they make doesn't work half the time. The company does claim to pay your ticket if your caught and cited. I am sure they give you the run-around once you call and try and file a claim.

The point I am getting to is if you want to get away with speeding, the easiest way(for me) was to fight the tickets in court. I have found that all you have to do is creat the instance of doubt that you were speeding. Subpoena the radar/laser guns records-check to see if they calibrated it according to mftr specs if not Motion to dismiss(lack of evidence to prove beyond a resonable doubt), also check to see if gun has had any recalls, warranty work, damage repair... if so exploit.
If everything about the gun is good, did the officer use the gun, or did he/she just guess how fast you were going(some do this its called presumed speed and its bullsh*t) subpoena the officers vison records (if they have 20/100 vision your free even if they have glasses/contacts) also was it cloudy, bright, night.. were there any other vehicle passing by that could *confuse the officer* also subpoena the officer's citation record that day, how many speeders did he nail that day(he could have had a hard on for people driving red cars...) look for patterns, judges/jury members are sometimes sympathetic twards that kind of stuff.
I have had to fight only 2 of 7 tickets and I won both. 5 times the freakin cops(THE State/city/counties only witness) did not show.

I hope is helpfull and aint too boring.

m21sniper

We were talking about LASER DETECTORS when paint color was discussed.

There are actually many more bands of radar than you list, and they all behave on the same basic principles. Until you get into the really longwave military search static-installation type radars, all of them are susceptible to various methods of RCS reduction.

Thanx for the heads up.

I don't think anyone here would disagree with any of that.

drnick

porken, i like your idea about angling the radiator and adding a vent in the hood. from what i understand the disturbed air exiting the vent enhances laminar airflow and reduces lift over the front axle. i supose leaning the radiator forward would allow the vent to go further forward on the bonnet increasing its aerodynamic effect. i would love to see a 928 with this kind of hood venting, i think there is one in carbonfibre but it also has a raised edge which i didnt think to enhance the aesthetics as much.

Mongoose

Ack! Sorry drnick, I just had to pipe in here.

Adding a vent in the hood will add energy to the boundary layer, which can help prevent separation. However, this is separate (but not unrelated) to laminar flow. And in this case, will decrease the likelihood that laminar flow occurs on the hood. More than likely it will increase the turbulence in that region. (turbulent flow = opposite of laminar flow)

Also, laminar flow serves to increase lift, wheras turbulent flow decreases the lift produced at the same airspeed/angle of attack/etc...

Turbulent flow does however reduce a certain kind of drag on a body. Turbulent flow (i.e. usually higher energy flow) causes the separation point to move aft on a body in an airstream. And this reduces pressure gradient drag.

So to sum up:
-A vented hood will add energy to the boundary layer at that point on the car.
-This may or may not decrease the lift at that point and aft, it depends on what the flow looks like in the first place.
-This will increase the turbulence at that point, and possibly aft of that point on the car.
-This may or may not increase the skin friction drag of the car from that point aft. Again, this depends on what the flow (and pressure gradients) look like.
-This will probably reduce the drag of the entire vehicle, but that depends on many other factors.
-The only way to tell would be to put the 928 into a wind tunnel and test it. (I wish)

(just finished a crash course in compressible aero)
Jason

inactiveuser92616

interestingly, my 1987 944NA rarely ever gets picked up by the "Your speed is ____" traffic radar signs.

m21sniper

Well the way the nose is shaped if it's not transparent to the signal(and im sure it's not), it would angle the vast majority of the return straight up into the air.

It should still get a return off the grill, windshield frame and interior though.
Maybe the plastic laminate inside the front windshield in your car is a reflective surface?

Heh.....at any rate, niiiiiiiiiiiiiiiiice.

Normy

I think you misread my earlier post: the lower edge of the radiator forward would mean that the upper edge was toward the back of the car; radar returns would be deflected up.

-I suspect that a good radar detector [Valentine] and a good lawyer would be more effective at preventing traffic tickets than an angled radiator....or any sort of fancy aircraft paint. Anyway, at least in Florida, they make more use of Cessna 182's than radar guns in speed enforcement on open highways. You can get away with 80 mph on the Florida Autobahn [I-95 north of Palm Beach county]. I know it- I was passed by an FHP trooper while sitting at 85 mph one day in Indian River county... he looked at me, slowly wagged his finger back and forth... I SLOWED down!

[reasonable! law enforcement, Florida-style]

N!

drnick

mongoose, thanks for the technical correction. i new it did something to speed up the airflow and thereby increase the pressure and of course this is all idle speculation untill its actualy demonstrated to have such an effect! i think it would look cool