Relationship to the Eppler Code
At its core the current method is closely related to the Eppler airfoil
design method (Eppler 1957). And "90%" of what is presented here on the
WWW is based on Eppler's method. Some of what follows will only make sense
to the experts and those experienced with the Eppler method.
Features common to both the Eppler code and PROFOIL
- Multipoint design capability allows for matching performance a various
- Segment descriptions of the airfoil with associated design angles of
attack and arc limits
- Constant velocity segment velocity distributions
- Trailing edge thickness parameter Ks specification through
iteration on various design parameters
- Cusped trailing edge airfoils
Features unique to PROFOIL
Most of the listed features of PROFOIL are not implemented in
PROFOIL-WWW. Why? Because setting up the forms support and error
trapping across the net would be too difficult. However, PROFOIL-WWW
has enough capability to solve most of the world's problems ...
related to low-speed airfoil design. But as mentioned in the overview,
a viscous analysis code is required to close the loop.
- Non-constant segment velocity distributions can be
adjusted to achieve a specified boundary layer development
- Specified anchor velocity for a given segment - Useful when dealing with
hydrofoil design when there are limitations on the velocity for cavitation
- Finite trailing-edge angle airfoils
- Misc single parameter prescriptions:
- Maximum thickness
- Maximum camber
- Other geometric constraints
- Pitching moment
- Trailing edge differential at closure arc limits -> Useful when trying
to control the amount of aft loading without necessarily having a
constraint on the pitching moment.
- Zero-lift angle of attack
- Trailing-edge velocity
- Segment prescriptions:
- Velocity distribution along the airfoil arc length
- Boundary-layer developments, such as the shape parameter H12,
linear stability amplification factor n as used in the e^n method
of predicting transition, the Eppler transition criterion curve, skin
friction, and more
Finally, it should be mentioned that PROFOIL is approximately 7000
lines of Fortran code (no graphics) written in a "structured" format,
and it is not a "new" or "modified" version of the Eppler code.
Hopefully, someday I will get around to writing a manual for a PC
version of the code.