Air Venture Cup racers were required to have 18" numbers on the bottom of the left wing and on each side (or vertical stab).  I had vinyl numbers on my plane for 5 years and took them off last year since I don't race anymore.  They were easily removed and caused no residual effect on the paint (automotive white, base coat-clear coat finish).  Indicated air speeds exceeded 200 kts over hours of racing (slightly less at cruising) with no lifting of the sharply cut corners or leading edges.  These numbers were on the plane winter and summer.

 

In other words, what a great way to detail an airplane and, if you don't like the results, it is easily removed.

 

However, one must think carefully about the effect on various parts that rely on laminar flow.  It takes very little to disrupt the laminar flow, thus causing an increase in drag and possibly a decrease in lift.  This means that the airplane should be retested for its flight characteristics at or near the stall after application of the wrap.  Before and after performance tests should also be noted.  Places to avoid flow disruption would be the first 2/3 rds of the upper wing, leading parts of the empennage vertical and horizontal stabs and possibly certain parts of the cowling.  Control surfaces should be rebalanced. 

 

I don't know if the number on the lower surface of my wing caused any effect, but I am sure that the numbers placed on the fuselage ahead of the tail cone had little effect because it is behind the location of the static port - an area of quiet boundary layer air. Forget the sponsor advertising stickers for the 2003 AVC.

 

 

Grayhawk

 

Congrats, Steve and Claudette, on your spectacular win at OSH.

Re the vunyl wrap: Does anyone know the effects on the boundary layer and 
airspeed? Any known drag numbers as compared to a smooth, waxed paint job?

Thanks,

John Schroeder
Lancair ES


On Mon, 03 Aug 2009 14:43:27 -0400, Steve Colwell <mcmess1919@yahoo.com> 
wrote:

> The wrapped Pulsar at OSH belongs to a friend of many years.   He is an
> aeronautical engineer and composites specialist who is aware of the
> potential problems.   Alex tested the wrapping material by attaching test
> panels to the leading edges and prop before committing to the whole 
> plane.
> He has had zero peel or lift, even on a couple of patches and punctures.
> The Pulsar had been flying for a couple of years and I would bet he was 
> very
> careful about prepping the surface before the vinyl was applied.  If you
> want quick,  inexpensive (and lightweight) graphics with a small 
> compromise
> of visible seams up close this is an alternative you should look into.  
> He
> had 2 out of 3 vendors in the Los Angeles area turn him down so some
> shopping will probably be required.  The vinyl wrap has been around for
> several years on busses, cars, vans, etc..
>
>
> Steve Colwell  Legacy
>
>
>
>
> "Pretty awsome!  And at a saving over painting.... Wow!  I wonder what 
> the
> chances are of it coming off in flight.  I would presume proper 
> application
> is important."
>
>
>




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