×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

racing wax

racing wax

racing wax

(OP)
A store around here sells "racing wax," guaranteed to make your car go faster by reducing drag. My question is, would this stuff really make a difference on a vehicle traveling below a couple hundred miles an hour? I can't imagine the the paint finishes on new vehicles are rough enough to cause a noticible decrease in speed and fuel efficiancy.

-Jon

RE: racing wax

I agree.  This is just another way for someone to separate you from your money.  There are many larger obstacles to airflow on cars than dust.

RE: racing wax

It can have an effect when you get up around 180 mph on something like a Winston Cup car but as the CD of these vehicles decreases, so does any surface effect. Most of the wind tunnel testing for R&D is done in primer.

We did testing a few years ago on boats and found the reduction in hull friction made a difference with drag boats made a difference on the clock. The slower te boat the greater the effect, since the faster classes had less hull surface in contact.

We also tried it on golf balls - got 5 to 10 yds longer drives. So there's something to be gained by surface treatment in certain cases, but I doubt the 'guarantee' has much data behind it

Keep the wheels on the ground
Bob
showshine@aol.com

RE: racing wax

Bob,
The boats I'm not surprised about because of water's density, viscosity and surface tension.
The golf balls though, sounds like there's $ to be made with that idea.  Maybe some kid wanting a summer job can polish golf balls for his neighbors.  He'll have to understand what's going on though because he's going to have to convince them it's worth it.

RE: racing wax

at low reynolds numbers, it's better to have a slightly rough surface to keep the boundary layer energized so it doesn't build up too quickly, causing more drag.  so, unless you're going around the track at 180 mph, all by yourself, it won't help.  profile drag is your nemesis.

RE: racing wax

That's why I prefer to keep a fine layer of grit on my car at all times. Sometimes the airflow gets disrupted by the "Wash me" written by some helpful (But obviously not an aerodynamicist) person.
Tony

RE: racing wax

Nice one!

RE: racing wax

OK guys, stop being so cynical.

Don't forget that the wax really does multiple duty:

(1) fills-in pits/pores within paint finish caused by impact damage and paint irregularities, that can appreciably "smooth-out" an overall "rough" finish.

(2) makes the surface relatively "non-adherent" for bugs, dust, debris, rain/moisture, etc.

(3) adds a thin layer over the paint finish for improved abraision resistance and a provides a temporary "wear-away" surface.

In aviation I've experienced the following:

(a) A very rough paint job reduced cruise speed of an O-2A acft by up-to 18-Kts [was ~150Kt with a glossy finish... reduced to 132-Kts at 75%-pwr with a rough "flat-camoflage" finish]. Sand-off and repaint "to spec" "improved" overall cruise airspeed up-to ~142kts!!!

(b) Many experimental or high performance airfoils have seen disasterous performance reductions due to roughness [especially on airfoils, due to premature/irregular flow separation]. Sailplane and "racing" pilots learned years ago that a "clean waxed" exterior provides a "winning-edge in contests... simply because of the improved micro-finish and reduced adhesion that "wax" provided.

(c) Boeing pays attention to minor exterior details... a 0.5% decrease in drag is probably worth several hundred-thousand $$$ in fuel expennse over the life-time of "heavy" [transport sized] acft!!!!

NOTE: on a dirty racing auto the improvements may be very slight... but between high speed racing vehicles, win-loss times are generally measured in 1/10s of seconds over an entire race! if the wax just keeps a few bugs from sticking, it may make a "winning" difference.

Regards, Wil Taylor

RE: racing wax

Is the paint on an aircraft aerodynamically necessary, or necessary for the protection of the skin of the aircraft? I'm just wondering how much a typical paint covering for, say, a 747 weighs. Are the passengers paying so that the airline can fly a ton(?)of advertising hoarding on every trip?   

RE: racing wax

jgm,
To give you some idea of paint weight, when the space shuttle was first built NASA painted the big liquid fuel tank under the shuttle white.  Shortly afterwards they stopped painting it because they realized the paint weighed 300 lbs and every pound they launch is expensive.

RE: racing wax

jgm...

Surface roughness is the key here. Polished metal and waxed paint are about the same.

Paint is there for (2) reasons.

Engineering: corrosion protective organic finish [primer] over inorganic-finish surface preparation [anodize, alodine, platings, etching/passivation, etc].

Decorative [or camoflauge]: "pretty" finish over corrosion protective finishes to please the customer's needs.

Paint adds considerable weight. For a small fighter [F-16], the primer and camoflauge paint [specialized heavy pigments] add up to about 80#. Large transports [747-400] can gain close to 1000# for a full primer/paint job [huge surface area]. Also, primer and paint touch-ups have been known to severely affect the ballasting of a large balanced flight control surface [transport elevator].

Note: highly polished "ALCLAD" skins have good corrosion resistance and low skin friction. Maintenance is easy IF the polished apearance is NOT allowed to deriorate... and repainting costs are obviously minimized***. ON-GOING MAINTENANCE is very critical if corrosion sets in, maintance.

American airlines has choosen bare-skin and decals as their "finish scheme" of choice. This approach is high maintenance on a daily basis [maintaining highly polished "pretty appearance" is demanding] ... but saves lots of weight and re-repaint cost/time.

Other airlines have choosen the opposite approach, since a majority of primary structure skins*** [IE: wings] are machined and cannot be successfully ALCLAD and/or polished... and still maintain good corrosion resistance on critical structure [they are generally anodized, primed and painted]. These Airlines choose the minimum daily maintenace approach... followed by on-going touch-up and occasional de-paint/re-finish every 6--8 years.  

The drag affects and maintenance affects of ACFT finishes have LOTS of economic affects!!!!

Regards, Wil Taylor

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources