Aerodynamics question

[Bacachero]

I saw a mythbusters show where they did an experiment to see if a car would get better mileage if they imitated the surface of a golf ball. It worked. I have heard people that get Hail damage claim it improves speed by a couple of knots. Ive also read a few post in this forum where people who wax their birds also see speed increase. If this surface shape works like this, Could this become a speed mod? check it out.

http://www.youtube.com/watch?v=XD27VIU9O4M

Lets hear some opinions!

[KSMooniac]

I can't watch the videos at work, but the dimpled surface only reduces drag if there is a turbulent and then separated boundary layer.  In order of least drag to most drag, it goes laminar flow, turbulent flow, separated flow.  The dimples help a turbulent boundary layer stay "attached" to the body when contour might otherwise cause it to separate and create a draggy wake.  Mooney wings are laminar flow over much of the surface before they transition to turbulent flow.  I don't know but would guess there is turbulent (and attached) flow over most or all of the fuselage.  Thus, dimpling a Mooney wouldn't help and would likely be a detriment if the wings were dimpled.

Wax reduces skin friction drag and is certainly helpful, independent of the laminar/turbulent flow status.

[Skywarrior]

Could lead to a new product line for MAC:

- "The New Mooney Titleist"

- Mooney M20DD "Big Bertha" (all magnesium)

- Mooney M20FU "Mulligan" (Auto Go-Around)

 

Chuck M.

[sleepingsquirrel]

Yes ,

  I concur, taking a ball peen hammer to the wings is not the best idea . One should concentrate on the the fuselage just aft of maximum frontal area. Dimpling (use the round end of the hammer) from here back will encourage turbulent flow . A turbulent boundry layer unlike a laminar boundry layer is relatively insensitive to flow disturbances  and will remain attached in areas of an adverse pressure gradient. (remaining attached is good) The flow seperation is caused by the designers need to reduce the diameter of the airplane from a  point somewhere just aft of the baggage compartment to the diameter of the navigation light fixture located at the end of the tail cone . (really, this reduces the over all weight of the aircraft and keeps it from being infinitely long) 

  An adverse pressure gradient is initally set up by the furious beating given to the air as it passes through the propeller disc.(remember the air was relatively calm , minding its own business until we came along). As discussed in another thread three blades may look sexier but greatly adds to the beating and consequently the adverse pressure gradient.  You are going to get a greater drag reduction doing this than reversing the brake calipers. Conservatively there will be 3kt/$ spent increase in speed. (excludes labor)

Because the laminar flow wing on the Mooney has a narrow drag bucket it is better to leave the plane tied down outside in the Southeast or Midwest in the Spring. If you are lucky  hail damage will dimple the wing randomly just behind the designed (known) flow seperation point of your Mooneys airfoil. Nature can produce this random pattern far better than you can. If your not so lucky and you get hail damage anywhere forward of where the flush rivets are call your insurance company and let them fix it. Better yet leave the hail damage and get the windshield mod for extra speed. For faster looks get a three bladed propeller.

 

[thinwing]

sleeping rodent...i think your physics being pre schrodinger,are not taking into account natural harmonic energy levels of the outer electron shells of the Mooney aluminum.Everyone knows bernoulli was a bedwetter...hence his theory fails to account for why a Mooney wing flys just as well ..UPSIDE DOWN...DUHHH...the point being ,that the dimpling,in order to be most effective,must occur..at the subatomic level...sinc kpc

[sleepingsquirrel]

Yes,

 I concur, subatomic dimpling occurs naturally to some degree but it is difficult to dimpil at the subatomic level with a ball peen hammer.  Our government has done extensive research in this and the only positive result was the $800 hammer.

I really didn't want to open this box for fear of finding a dead cat, or a live cat for that matter. (ref: anyone fly a cat in a Mooney) However, research has been done at this level by Stan Portigal ,Eclispe Aviation.(ref: FAQ)

"This light should give you an extra 5 kts because of reduced optical friction from the light. If you install one of these on a Piper, Bonanza, or a Cessna, you should get an additional 20 kts because the air molecules see the Fresnel lens and figure it's a Mooney coming at them"

Have you ever noticed your Mooney goes faster at night? It's because of the light. You can't see the air molecules getting out of the way because trying to observe this will cause the wave function to collaspe. The wave function doesn't disappear as most scientist think it  just reappears in a different form <notably the Mooney wave function>.

Remember Einstein's greatest discovery was not that time is relative but that time is money.  As new as I am to the Mooney airframe even I know it takes money to make a Mooney go faster. There are lots of ways to skin this cat some of them yet unexplored.

[thinwing]

Well by now I am sure Bacachero is truely regretting ever starting this strange thread!!Personally,after reading the last two posts,I fell unwell...like I am in a parallel universe with nobody at the helm,headachy,skin flushed and somewhat nauseated..(ref:CO in your cockpit ,by thinwing)even Al Mooney is crawling deeper in the grave.kpc

[sleepingsquirrel]

Yes,

I concur, But as Skywarrior hinted the only way to get a dimpiled Mooney to fly faster is for it to spin like a golf ball. Everyone knows that you shouldn't spin a Mooney.  Gee,  Bacachero I'm sorry , I thought we were all pretty much on topic. I'm going to sleep now.