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Public Domain Aeronautical Software (PDAS)  

One of the most important considerations in the design of a commercial transport aircraft is the aircraft's performance during takeoff and landing operations. The aircraft must be designed to meet field length constraints in accordance with airworthiness standards specified in the Federal Aviation Regulations. In addition, the noise levels generated during these operations must be within acceptable limits. This computer program provides for the detailed analysis of the takeoff and landing performance capabilities of transport category aircraft. The program calculates aircraft performance in accordance with the airworthiness standards of the Federal Aviation Regulations. The aircraft and flight constraints are represented in sufficient detail to permit realistic sensitivity studies in terms of either configuration modifications or changes in operational procedures.

This program provides for the detailed performance analysis of the takeoff and landing capabilities of specific aircraft designs and allows for sensitivity studies. The program is not designed to synthesize configurations or to generate aerodynamic, propulsion, or structural characteristics. This type of information must be generated externally to the program and then input as data. The program's representation of the aircraft data is extensive and includes realistic limits on engine and aircraft operational boundaries and maximum attainable lift coefficients. The takeoff and climbout flight-path is generated by a stepwise integration of the equation of motion. Special features include options for nonstandard-day operation, for balanced field length, for derated throttle to meet a given field length for off-loaded aircraft, and for throttle cutback during climbout for community noise alleviation. Advanced takeoff procedures for noise alleviation such as programmed throttle and control flaps may be investigated with the program. Approach profiles may incorporate advanced procedures such as two segment approaches and decelerating approaches. The landing performance considers the application of wheel brakes, spoilers, and thrust reversers. (NASA Langley Research Center)

The italicized text above is from the official NASA release to COSMIC. If you would like to examine the original source code for this program as well as a source file converted to Fortran 90 free format, you may download tol.zip and explore. The zip file also contains two sample cases. The reference document noted below is a good description of the computer program, but it is not a user's manual describing the input variables and program codes. I have started a list of input variables and hope to have it pretty well filled out by the end of 2009.

This program is designed to follow the letter of the law in defining takeoff and landing field lengths. The other main reference for this program is the collection of Federal Aviation Administration Regulations, as many of the procedures coded here are spelled out in the regulations. You can read these regulations by going to the FAA Site and following the link to Federal Aviation Regulations under the heading Regulations and Guidelines. From there, you want Current Federal Aviation Regulations and follow this on to Part 25 for Commercial Transport Aircraft. This computer program is in accordance with the regulations as of June 1979, but I cannot guarantee its current conformance.

References:

  1. Foss, Willard E., Jr. A Computer Program for Detailed Analysis of the Takeoff and Approach Performance Capabilities of Transport Category Aircraft. NASA Technical Memorandum 80120, June 1979.
  2. Hall, Albert W.: Takeoff Distances of a Supersonic Transport Configuration as Affected by Airplane Rotation During the Takeoff Run. NASA Technical Note D-982, October 1961.
PDAS home > Contents > In Progress > TOL
Public Domain Aeronautical Software (PDAS)