Stock airfoils

[pat king]

I have been asked why I offer several airplanes with stock airfoil instead of symmetrical airfoil for flying the pattern. The airplanes with stock airfoil are for Profile Scale competition. As a scale judge I see a great need for airplanes that are not just bricks on a string. There are literally hundreds of airplanes available for flying the pattern. Offering designs to try to address the stunt arena is not good business. I have a few, but not many.

Pat

[Brett Buck]

I have been asked why I offer several airplanes with stock airfoil instead of symmetrical airfoil for flying the pattern. The airplanes with stock airfoil are for Profile Scale competition. As a scale judge I see a great need for airplanes that are not just bricks on a string. There are literally hundreds of airplanes available for flying the pattern. Offering designs to try to address the stunt arena is not good business. I have a few, but not many.

Pat

  What does "stock airfoil" mean? Do you mean cambered (which I glean from the context)?

    Brett

[Dave Hull]

Scale airfoil?

[pat king]

By stock airfoil I mean exactly that, the airfoil that the full scale aircraft was carrying when it left the factory. From my auto racing roots I refer to things that are the way they left the factory as "stock". Some early airplanes had undercambered airfoils, some later airplanes have flat bottomed airfoils like the Clark Y. Many WW II fighters had airfoils that lend themselves to aerobatics. While not fully symmetrical they are a very long way from flat bottomed. My Profile Scale Extra 330 SC has the fully symmetrical airfoil that the full size aircraft carries. That should make it competitive with most any non-flapped stunter. Some of my designs that are intended for Profile Scale competition were originally offered with symmetrical airfoils. Many of those have been updated to carry the same airfoil as the full scale airplane to prevent loss of points in national level competition.
My profile P 47 stunters are profile versions of the Bill Werwage World Championship airplane. They look like the full scale airplane, but would lose points in static judging for Profile scale. Those airplanes are designed to fly the full pattern. In most cases I am not trying to produce models for flying the pattern in competition. Many of my Fun/Sport airplanes have fully symmetrical airfoils that will perform stunts well, but not at a competitive level.

Pat

[Howard Rush]

Here you go: https://m-selig.ae.illinois.edu/ads/aircraft.html  You won't be flying at the same Reynolds or Mach number, but you'll be authentic.

Check out the B-17.

[pat king]

Thanks Howard,
That list is my first "go-to" for determining the original airfoil for scale airplanes. As you say, the Reynolds numbers and Mach numbers do not match the full scale aircraft, but that does not really matter for scale competition. My goal for scale airplanes is to provide kits that can be competitive and do not have ridiculously high wing loading and will actually fly level without significant angle of attack.

Pat

[Walter Hicks]

This is one of Pats Scale Kits, Extra 330. Even though it is profile scale , the airfoil and wing is very good, tail volume coefficient, moments etc are good for stunt, Symmetrical airfoil. 640 square inches of wing area I made the flaps slightly bigger than the kit . RO Jett 67 SE for power my bet is that it will be a good profile stunt plane even with a scale wing and airfoil! Plane is yet to be completed needs pushrod, tank.

[pat king]

Walter,
Very nice!!
That airplane should be competitive in Profile Scale and/or Profile Stunt. The full size airplane is designed for aerobatics, so I don't see any reason that the model will not stunt well. It can be used to compete in both classes if the paint scheme can be documented. I like the paint scheme.

Pat