Anti-skid coating on 737 wing

pscraig · September 25th, 2003, 09:18

While flying on a USAirways 737-400 last weekend, I noticed that the wing area near the emergency exits was coated with an anti-skid coating, and the surface appeared very rough. Does this not disrupt the flow of the air over that section of the wing, much like frost or ice? I can understand the need for passenger safety in an emergency, so is the effect on the wing that negligible?

EatSleepFly · September 25th, 2003, 10:54

Can't disrupt anything too bad...almost all low-wing airplanes have it.

pscraig · September 25th, 2003, 12:02

True, but this was very coarse and I thought of the parasitic drag at 400+ kts

kellwolf · September 25th, 2003, 17:58

Doesn't parasite drag decrease with altitude? At around 300 kts, I'm assuming you would be fairly high up.

Minuteman · September 26th, 2003, 00:24

Induced drag decreases with airspeed, form and parasitic drag increase with airspeed.

The coating is probably so far aft on the wing and close to the fuselsausage that its effect is negligible. Sometimes a rough surface downstream of the transition from laminar flow can be beneficial by energizing the boundary layer from the free stream (similar function to vortillons).

Sharks have been imparted with this gift of textured skin too. On them, their skin has small ridges (like couderoy). 3M was working on a skin surface for Airbus a while back that had similar textures. Last I heard, they were experimenting with different ridge spacing and heights, but it was really expensive stuff ... like a hundred bucks a square foot. An A320's wing area is around 1300 ft², so it better offer big savings.

The ridges are called "riblets" is they're prependicular to the flow, "rivulets" if they're parallel, and they both make a swhooshing sound as the airplane taxis around the airport.

Up next, "speed holes"...

B767Driver · September 27th, 2003, 10:45

pscraig,

That "anti-skid" coating that you observed is actually utilized for the airlines de-icing procedures. Under certain situations, one of the cockpit crewmembers may be required to visually observe a section of the wing to inspect for ice contamination. The "rough-smooth-rough" strips that you noticed enable the pilot to determine if ice remains on that section of the wing from his vantage point inside the cabin.

Clear ice can be very difficult to discern from the grey, smooth section of the wing. The strips aid in the visual determination.

Hope that helps.

(BTW, the laminar flow boundary is so disturbed at that section of the wing that is provides almost no lift...so the placement of the "strips" at that location has a neglible affect on lift or drag.)

Doug Taylor · September 27th, 2003, 16:05

MD88Pilot would know!

He's the guy who gave me my Beech 1900 type ride!

B767Driver · September 27th, 2003, 19:41

Hi Doug,

I've been enjoying your website, lately. Not doing much flying on reserve....gotta do something!

Eric

September 25th, 2003, 09:18	#1
pscraig Senior Member Join Date: Jul 2001 Location: Houston, TX Posts: 1,021	Anti-skid coating on 737 wing While flying on a USAirways 737-400 last weekend, I noticed that the wing area near the emergency exits was coated with an anti-skid coating, and the surface appeared very rough. Does this not disrupt the flow of the air over that section of the wing, much like frost or ice? I can understand the need for passenger safety in an emergency, so is the effect on the wing that negligible?

September 25th, 2003, 10:54	#2
EatSleepFly Old Skool Join Date: Dec 2002 Location: ?? Posts: 4,600	Re: Anti-skid coating on 737 wing Can't disrupt anything too bad...almost all low-wing airplanes have it.

September 25th, 2003, 12:02	#3
pscraig Senior Member Join Date: Jul 2001 Location: Houston, TX Posts: 1,021	Re: Anti-skid coating on 737 wing True, but this was very coarse and I thought of the parasitic drag at 400+ kts

September 25th, 2003, 17:58	#4
kellwolf Old Skool Join Date: Jun 2003 Location: Memphis, TN Posts: 13,879	Re: Anti-skid coating on 737 wing Doesn't parasite drag decrease with altitude? At around 300 kts, I'm assuming you would be fairly high up.

September 26th, 2003, 00:24	#5
Minuteman Old Skool Join Date: May 2003 Location: Austin, TX Posts: 1,529 Blog Entries: 1	Re: Anti-skid coating on 737 wing Induced drag decreases with airspeed, form and parasitic drag increase with airspeed. The coating is probably so far aft on the wing and close to the fuselsausage that its effect is negligible. Sometimes a rough surface downstream of the transition from laminar flow can be beneficial by energizing the boundary layer from the free stream (similar function to vortillons). Sharks have been imparted with this gift of textured skin too. On them, their skin has small ridges (like couderoy). 3M was working on a skin surface for Airbus a while back that had similar textures. Last I heard, they were experimenting with different ridge spacing and heights, but it was really expensive stuff ... like a hundred bucks a square foot. An A320's wing area is around 1300 ft², so it better offer big savings. The ridges are called "riblets" is they're prependicular to the flow, "rivulets" if they're parallel, and they both make a swhooshing sound as the airplane taxis around the airport. Up next, "speed holes"...

September 27th, 2003, 10:45	#6
B767Driver Old Skool Join Date: Sep 2003 Posts: 1,888	Re: Anti-skid coating on 737 wing pscraig, That "anti-skid" coating that you observed is actually utilized for the airlines de-icing procedures. Under certain situations, one of the cockpit crewmembers may be required to visually observe a section of the wing to inspect for ice contamination. The "rough-smooth-rough" strips that you noticed enable the pilot to determine if ice remains on that section of the wing from his vantage point inside the cabin. Clear ice can be very difficult to discern from the grey, smooth section of the wing. The strips aid in the visual determination. Hope that helps. (BTW, the laminar flow boundary is so disturbed at that section of the wing that is provides almost no lift...so the placement of the "strips" at that location has a neglible affect on lift or drag.)

September 27th, 2003, 16:05	#7
Doug Taylor Agent Smith Join Date: Dec 1969 Location: KSDL Posts: 41,241 Blog Entries: 1	Re: Anti-skid coating on 737 wing MD88Pilot would know! He's the guy who gave me my Beech 1900 type ride!

September 27th, 2003, 19:41	#8
B767Driver Old Skool Join Date: Sep 2003 Posts: 1,888	Re: Anti-skid coating on 737 wing Hi Doug, I've been enjoying your website, lately. Not doing much flying on reserve....gotta do something! Eric

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