I want to make a portable smoke generator
 

I like how well smoke trails work for visualizing air flow in wind tunnels. Why not do the same thing on a moving car?

(note: the above is not a rhetorical question--if there's some reason it won't work I'd sure like to hear it)

How do smoke generators generate smoke, exactly? Are they available off the shelf...and if so, where are the shelves? Like most ecomodders I'd be happy to make my own (if I knew how) to save a few bucks, but if they're available from Crazy Eddie's Aerodynamic Emporium, factory seconds for $39.95, I'll just buy one.

The idea is, fix the wand to the car, drive with a chase car alongside, turn on the smoke generator, have a passenger in the chase car take pix and vids, mount the wand somewhere else and repeat as needed. Technical advice/assistance will be greatly appreciated.

I think you'd need a guy to run the wand too- move it around like you often seem em do in wind tunnels.

Get a fog machine and a hose running to the front grill of the car poking out a bit... then run it off a 12v dc to ac converter plugged in your cig lighter!

Wow that would be an epic sight to see hahahaha

I love the idea, but got a snap vision of the fire truck racing up behind you to save you from incineration ;).

You may actually br able to get smoke in a bottle, or just light up a big cigar and blow it through a hose (just kidding) ;).

Maybe tap off the exhaust and use the heat to generate smoke.

regards
Mech

I was thinking about this a while ago, not so much a portable smoke machine for aero while driving, but rather find a windy day and a flat place to park, try to face the wind's general direction to the best of your ability, and then mount your tuft on the end of a wand and try to look for patterns while moving the tuft around from outside the car.

But then I got tired of thinking about that and went back to my usual thinking about burritos, and about the anatomic features of women and so forth

All you need to do is follow a Chrysler product and you got yer smoke machine.

Spraying mist might be a better idea.

A little oil in the intake will produce a lot of smoke at the tailpipe.
Put the smoke producing car in front of the subject car and watch and learn.

it's a little messy but sailplanes sometimes use oil on the wings wich than produces streaks and patters, this will tell them things like flow sepparation etc and the best place to put turbulators. it might not apply to cars because of the different airflow over a car but it's worth a try

I've seen great airflow lines over my car after driving in the wet and the dirt sticking in the right places. I should've got a picture. It happens every so often. As for the oil in the intake, it takes very little oil to blow out the breather and into the intake before you have huge plumes of white smoke behind you. Ask me how I know :(

Model airplaners have found a 50/50 mix of diesel and canovus form release oil makes the best smoke for acrobatic planes. ATF works well but smells odd.
That said, Check your state laws.
In most states even having a smoke generating device, nevermind using it on the road, is illegal. In some you will lose your car and get a heavy fine. The authorities don't want big smoke clouds blocking other drivers vision.

I found a picture of an f-18 with aerodynamic test equipment on board. They had a load of nozzles fitted to places they wanted to study and pumped a liquid through them that stained the body, revealing the airflow. Here's a link to the picture:http://www.dfrc.nasa.gov/Gallery/Pho...8-0212-002.jpg
I found it elsewhere in the nasa site with a description but can't find it for now.

ollie

Check out McMaster Carr's smoke candles and pens. They also have a 120VAC smoke generator, but getting onboard power would be a challenge and it's a bit expensive (~$500).
Grainger has some stuff here as well.

Jack - I recently saw a film crew create A LOT of smoke from a single small source on a moving boat to simulate a foggy day in a harbour on a calm day. Tracking down a movie effects company might lead you in the right direction.

Also, I suspect the film industry is subject to regulations that might mean whatever they're using may be less noxious than simply burning oil/whatever.

smoke
 

There are commercial smoke generators.SAE published an entire book on imaging,including smoke and it might contain info on fabrication.I've glanced at it but don't own a copy.Texas Tech Aero Lab had a commercially produced smoke unit we used on a model in 1991.$1,100.00 US was the price at that time.A non-toxic oil is electrically heated and flashed off as smoke in a chamber exposed to the windtunnel airflow and flows to the rake,exiting at the exact velocity of the tunnel's flow,so as not to introduce turbulence right at the rake.------------- To do this on a moving car would require some fanagleing,as well as providing a sinewave inverter powerful enough to run the unit.---------------- You might cobble up a DC- powered unit to do the heating and experiment with a ram tube you could calibrate to match to the car's outer flow field.--------------- Demonstration parachute teams and aerobatic airplanes both do smoke.I think the parachutists use smoke bombs.They can be purchased at HVAC suppliers in sizes up to 50,000 cubic feet.The thing about them though,is that once you light them,they burn to conclusion----------------- I think the aerobatic planes spray oil onto the exhaust system.Don't know for sure.-------------- A bunch of us have settled on yarn tufts taped to the car for proof of flow.Darin has a boom which supports a video camera and he's self contained.I end up getting friends to drive "chase" cars and operate the camera to "freeze" the action.

I've thought of this sort of thing in the past as well.
I second what Metro said about trying to find an special effects outlet.
On a much smaller scale ( If the price on the movie set sized one is too steep ) , you could buy a home smoke machine ( smoke generator ) once Halloween is over and they drop the prices.You would really need to pump out a lot of smoke with it though .... and where would you plug it in at ??
I tried one and it didn't put out enough smoke once the fan kicked on in my small DIY wind-tunnel.
Since they are for use around people, they would certainly be more environmentally friendly than the other options given so far.

( MOTHER would thank you ;) )

BTW, How's MAX coming along ? I suddenly got really interested in the car when I saw the aero mods planned. It's cool how that you retained the 'classic' look, yet have a car that is very streamlined. Well done !


( Hmmm... O.K. so maybe the Halloween smoker wouldn't work. Well hmmm... what about a large Thermos of dry ice connected to your wand ??? ... grabbing at straws here.

EDIT : Sorry for posting an idea that was just mentioned. I rushed in without thinking.

One more straw to grab at - A bug fogger ( minus the toxic poisions ). That would be portable and it already comes with ( sort of ) a 'wand'.

bugs
 

Cd,your brain must be as twisted as mine! I grabbed a second-hand CRAFTSMAN bug fogger at a local flea-market for $15.I've made no attempt to fire it up so she languishes amidst my mountain of "treasure." When time allows,I'll research the oil used in windtunnels.Shell makes one I'm pretty sure of,although it's probably a "special" and not locally available.

I saw a device that ecomodders were using back in the '70s that consisted of a funnel pointed into the wind. The funnel was then connected to a length of clear tubing filled with colored fluid. As the car got up to speed, the fluid was pushed out of the tube on the area needing to be tested. There is a certain name for the instrument, but I cant think of it now.
It produced the exact same results as those shown in the F-18 image.

The magazine that had this article on ecomodding was published around 1978, and I have long since forgotten the name of it. It was devoted mainly to hot rods - in fact the car that tey were ecomodding was a '69 Camaro.
( Imagine that ! )
They added a large air dam to the front of the car and did coast down testing as well.
P.M. me if anyone recognizes the magazine I am talking about.

Sorry for the hijack - back on topic please ( P.M. me instead please )

Thanks, that should hold me for a while. chuckm, I followed your links, and found a product at Granger (90 second chemical smoke generator, 600 cubic feet, no harmful residue etc blah blah) that seems worth the risk for an experiment. At nearly 7 cf per second, it should be visible to 60 mph as a discrete line of smoke. I'll get a box of 10, fabricate some sort of chamber/wand for it and report back.

Re the legality, well...I don't plan to do it in town, I'll carry a copy of Mother Earth News with me so I can show it's for a good cause, I'll practice my innocent smile ("But officer, smoke generators weren't mentioned in the driver's handbook and it wasn't on the test!") and once it hits my wake I believe it will be diluted about 80 to 1 by the surrounding air and not too noticeable. I think I can be discreet--we have a lot of low occupancy roads in rural Southern Oregon--and surely I can talk my way out of getting my car impounded if I proooomise I'll nevernever do it again.

As for oil-in-the-exhaust generators--I've used corvus oil in my air show performances (yet another aspect of my misspent youth--if I ever write an action-adventure novel I have the "about the author" credits in the bag) but the high cfm is going to put the car in a cloud, not produce a discrete stream of smoke. Ditto re skydivers' smoke generators, they too make a huge amount of smoke. Ditto re following a smoke generating car--its wake is going to scramble the smoke into a cloud. Y'all may already know that stuff; sometimes it's hard to tell when somebody is kidding on the Internet.

I think smoke-on-the-fly might be an interesting alternative to tuft testing and/or oil-and-lampblack testing if it can be done cheaply (and discreetly) enough--and a $20 box of chemical smoke generators is less threatening to the wallet than a $1000 oil vaporizer. So give me a couple weeks and I'll tell you how it worked.

PS--Frank Lee, you may be right, it might be better to make the wand moveable rather than reposition it every trip. Maybe I can make something passenger-actuated.

Video documentation Pleaseeeeeeeeeeeeeeeee!
 

When you arrive at your moment of temporary insanity,please get someone to record it so we may all benefit from it, as well as pass the hat to raise funds to bail you out of jail.Kidding!------------ I'm not admitting to anything myself,but Estes model rocket dry-cell ignition systems make a great way to ignite fuzed smoke bombs that find their way into a perforated metal can which has stolen a ride on a persons rear bumper late at night on a deserted road where flash photography can capture the image of the smoke trail which a light breeze safely blows from the test track,away from any unsuspecting motorist who might happen along about then.:thumbup:

DON'T DO IT!!! When Homeland Security catches you doing your terroristic activities they will either blow your brains out all over the road or send you to Guantanimo. :eek:

I used to do nuclear clean-room filter testing and duct tracing using smoke generators. Google DOP or dioctyl phthalate smoke generators. You can buy them or make them. Some are as small as a tin can. It will take some compressed air and a small heat source. They produce tons of smoke and it is harmless stuff. It is theatrical smoke and is what you've seen being produced in wind tunnel tests.

Coincidence? Portable fog generator advertised in my local Home Depot flyer yesterday for $29.95.

FYI, someone who has worked in wind tunnel testing provided me with this information:

EDIT: link to smoke generator brochure PDF from that company - http://www.aerolab.com/downloadable-...enbrochure.pdf

Hey guys, I didn't re-read this entire thread, but if has not been mentioned, I wanted to suggest smoke used in acrobatic flying / parachuting.

http://worldwar2headquarters.com/ima...rogs-smoke.jpg

Those are smoke canisters that are ignited and continue to burn until they are depleted. i.e.; no way to shut them off. I would submit that a quick shut-down is a design requirement, so that you don't get your brains blown out all over the road or sent to Guantanamo.

Darin's description of the hypodermic tube with current passing through it sounds like the best idea to me. Anyone know where you can find such small tubing in small quantities?

Anybody proposed e- cigarette ( https://en.m.wikipedia.org/wiki/Electronic_cigarette )? Its basically smoke generator, battery operated, quite cheap. All you need is fog generator liquid.

To prevent possible problems of using smoke on the road, I was thinking of a fog / smoke source and using a large back pack leaf blower to provide the wind....would this simulate driving closely enough?

Welcome to Ecomodder; no.


:)

I'm in favor of a 4ft arm like a windshield wiper on the front bumper. The arm could swing though 180° and the emitter could traverse the arm. Covering the entire frontal area of the vehicle.