Commuter Airplane design optimization

[SlideRule]

A Study of Commuter Airplane Design Optimization {NASA-CR-157210)}, KU Center for Research, contains 457 pages of theory, descriptions, flow chart, equation, formula, program listing, illustration, chart, graph, etc., to present " … the work performed from August 15, 1977 through May 31, 1978 under the funding of National Aeronautics and Space Administration Grant NSG 2145.
     This project is a follow-up of research performed at Kansas University from May 16, 1976 through July 31, 1977. Both projects were aimed at enhancing the usability of the General Aviation Synthesis Program (GASP). GASP program is an assembly of computerized design methods to aid in the preliminary design phase of, specifically, general aviation airplanes.
…
     More specifically, attention will be given to the determination of … stability and control characteristics in the preliminary design process."

BEST!
SlideRule

[Maximilian Hohmann]

Hello!

Interesting. But the programs in this paper are all written in FORTRAN and need to be run on large(ish) computers. Airplane design went straight from sliderule to mainframe and mostly bypassed the pocket calculator... When I started to study aerospace engineering two years after this paper was published, one of our early tasks was to do the FORTRAN course.

Regards
Max

[rprosperi]

(11-12-2020 12:52 PM)Maximilian Hohmann Wrote:  Hello!

Interesting. But the programs in this paper are all written in FORTRAN and need to be run on large(ish) computers. Airplane design went straight from sliderule to mainframe and mostly bypassed the pocket calculator... When I started to study aerospace engineering two years after this paper was published, one of our early tasks was to do the FORTRAN course.

Regards
Max

You missed the HP-25 program in section 8. It's an odd program, step 01 is [R/S], but I didn't read the full section to understand operation; maybe there's a reason for that.

[Maximilian Hohmann]

Hello!

(11-12-2020 01:23 PM)rprosperi Wrote:  You missed the HP-25 program in section 8. It's an odd program, step 01 is [R/S], but I didn't read the full section to understand operation; maybe there's a reason for that.

I found it now. A little explanation is given on page 138 of the document, but I could not (quickly) find instructions of how to use the program and/or what values need to be entered in which order. The R/S at the beginning seems to make little sense to me. There is a loop but it goes to line 19. Maybe in an earlier version the loop went straigt to line 1? Or whoever programmed this did not have much experience with that calculator.

Anyway, the paragraph about that HP-25 concludes that the simplified calculation is too far off from real-world values to be of any use...

Regards
Max

[SlideRule]

an excerpt from A STUDY OF COMMUTER AIRPLANE DESIGN OPTIMIZATION (page 8.11)

" 8.5 HAND CALCULATION
With the aid of an HP 25 calculator a hand calculation was done for
airplane C. See Appendix C for a threeview and data. Table 8.3 shows the
results of the calculation. Comparison with the computer-run indicated
perfect agreement. "

Every tool has inherent limited utility, including the much admired and coveted HP-25. This post neither emphasized nor excluded the marginal utilization of the latter as an adjunct for the computer analysis. Hopefully, the non-computational device material (theory, descriptions, flow chart, equation, formula, program listing, illustration, chart, graph, etc.) is suitable and of at least modest interest for some members of the forum irrespective of the minor contributions of the venerable HP-25.

BEST!
SlideRule

[Maximilian Hohmann]

Hello!

(11-12-2020 03:00 PM)SlideRule Wrote:  " 8.5 HAND CALCULATION
With the aid of an HP 25 calculator a hand calculation was done for
airplane C. See Appendix C for a threeview and data. Table 8.3 shows the
results of the calculation. Comparison with the computer-run indicated
perfect agreement. "

Yes. I saw that too. But isn't it the normal way to verify the results of a computer program (unless it is too complex), to check it's results against a manual calculation? I did (and do) that with all programs that I wrote (and write). This can be done with any calculator. The authors of that paper happened to have access to an HP-25, but as much as I like that calculator myself - one of my favorites of all time - this does not specifically contribute to it's merits.

Regards
Max