There are 3 types of Drag at work during flight - Profile, Induced & Parasite. In aircraft flight it is a delicate balance of lift and drag, in boomerang flight it is a matter of creating the amount of drag desired.
Profile Drag: is caused by the airfoil itself. The layer of air closest to the wing creates friction and travels slower over the wing. Slots and deflectors are two methods of controlling this boundary friction.
Induced Drag: is created at the back of the airfoil. The air moving over the top hits the air flowing underneath and drives it downward, interrupting the smooth flow of air.
Parasite Drag: is resistance from the rest of the aircraft.
Airplane wings are attached at a slight angle to the longitudinal axis of the airplane to take advantage of Newtons's 3rd Law of Motion. As the speed of an aircraft is increased due to more powerful engines and other technological advances - that angle as well as the airfoil are changed to produce a more neutral (lower) lift coefficient. This lower coefficient makes the aircraft more stable and easier to fly.
For lower speed aircraft. This airfoil produces the most lift at the lowest speeds.
The following airfoils are newer and typically better at faster speeds. A less pronounced leading edge and a rounder underside tends to produce a more neutral lift. This means more control for aircraft at higher speeds.
Stealth - very unstable
Boomerang Airfoils - the Basics
Boomerang airfoils can be any of the airfoils found on aircraft. They can also be radically different to produce various flights.
Boomerangs can be modified by drilling holes in their wings, placing tape spoilers on the top or the bottom, or tape trailers behind the wing, or rubber bands wrapped around the wing to create drag over the top and along the bottom. Some people use weather stripping to create a spoiler on the top of a wing, or just a coin to create a raised area.
Taping weights to boomerangs is a very effective way to increase the distance as well adjust certain aspects of the flight, such as the trajectory or hover time and flight path.
Because of the different shapes of boomerangs and the wide ranging density of woods (even from the same mill and the same specifications) there are no hard fast rules governing the flights of boomerangs.
Traditional Boomerang Airfoil:
Undercut produces more spin and makes for a more stable and more accurate flight.
A lower flight path can be produced by building the boomerang with a very laid back leading edge (subsonic or supersonic airfoil) or by using any of a number of drag creating methods.
The top choices of throwers to control the flight; whether for wind, distance, or trajectory, are weights in various positions and/or holes, tape are other materials attached to the wing to create drag.
Creates drag to keep the flight low and reduce the speed of the spin. A spoiler near the leading edge creates more drag than near the trailing edge. For short distance boomerangs like a Competition Fast Catch the spoiler near the front keeps the flight lower than a spoiler at the back. Spoilers are also a very effective way to fight a strong wind.
A trailer of tape creates much the same effects as the spoiler but not as pronounced. Blunt leading edge creates a slower spin & a shorter hover. Blunt leading edge and a short trailing edge creates a rounder flight as well as a slower spin & a short hover.
Special concave undercut creates turbulence which holds the flight low.
Create turbulence and tremendous amounts of drag. They force the flight to stay low and fight strong winds. They can be various sizes. The closer to the tip, the greater effect they have. Concave shapes carved into the underside of the wing also create turbulence and help keep the flight low. The Colorado Boomerangs Condor Comp has a very special concave cut into the underside. These concave cut keeps the flight low throughout the flight and really help put the brakes on as it is coming in.
Because of the different shapes of boomerangs and the wide ranging density and thicknesses of woods (even from the same mill and the same specifications) there are no hard fast rules governing the flights of boomerangs.
Field testing and experimentation is the only way to truly determine flights.