The Cooper Harper Rating (CHR) scale is definitely a universal Handling Qualities reference and the most important scale used in Flight Test. It is probably one of the strongest binding links connecting the 1960’s era of flight testers to those of today.
Developed in 1969 it has since been widely used and studied all around the world. Numerous research projects have been done on the scale’s use and other studies trying to propose modifications or replacements. It has been so widely used and recognized, that even if it has some flaws, it will always be the scale to use for Handling Qualities. Proper use and especially pilot understanding of its use can minimize issues like intrapilot or interpilot variability and errors and make the scale an effective engineering tool.
For those of the flying qualities or flight test engineers and pilots who have extensively studied it and used it in research, the CHR is like a living organism. You always have to respect it, not rush it and acknowledge its weak points. Then using it just becomes a pleasure.
Completing this month 3 years of extensive use and study of the scale, I went back to revise the first Greek version I had created. Surprisingly (or not), I did a significant number of changes to it considering my better understanding of the scale and the language. Will it ever be used? Probably not, because then the whole report will have to be translated to explain the wording used – as for other languages. This translation is mostly for archival purposes and a tribute to Cooper and Harper for their contributions to flight test.
After being involved in long term discussions on a new Variable Stability/In-Flight Simulator aircraft, I was tasked to produce the top-level specification write-up. The final document describes the required technical specifications for a fighter-type VSS from degrees of freedom to safety system, modes of operation and desired performance criteria. The spec document is going to serve as guideline for a feasibility and cost study.
The F-16 VISTA shown in the image above has been by far the most impressive In-Flight simulator ever built. However, the problems it has been experiencing have been multiplied and it is scheduled to get retired in few years, currently with no planned replacement.
Projects like this are fun, as long as you have an appreciation of what it takes to complete them and you are willing to make the effort, pay the cost and take the risk they require.
A short flight in Black Shape Prime. Good looking and nice handling little airplane with an interesting stall, that has been considered as a trainer by various Air Forces.
Best week of the year so far attending the AIAA Aviation 2016 and AIAA Flight Test Conference in Washington DC. Aviation state-of-the art presentations and meetings with some highly distinguished individuals provided great inspiration for the younger of us to follow their steps and continue progressing aviation technology. On the side of the conference a long awaited visit to the Smithsonian National Air and Space Museum took place. Words cannot describe the awe you feel standing in front of those marvels of aerospace history; it’s like being in the Mecca of aviation. (By the way… 4 years of aeroscience blog!)
NASA Administrator Charles F. Bolden Jr. announcing X-57 Sceptor
Major General Joe H. Engle, X-15 and Space Shuttle Test Pilot telling some amazing stories
My X-15 poster signed by the last living X-15 Test Pilot…
The Wright Flyer!
Legendary Spirit of St. Louis
The original Apollo 11… (Speechless)
Every year the ITPS courses are enriched by including new subjects and exercises. This year for the fixed wing Graduate course, a week was added on Aerodynamic Modeling using Dynamic Flight Test Techniques. The following shot comes one of the preferred techniques used for fighter a/c modeling: Split-S. The data gathering portion of the maneuver is pretty short, timing roughly the initial 3-4 seconds, with g build up rates in the order of 2g/sec till reaching the desired g limit and before hitting the -70deg pitch angle. The g-load is then relaxed for the recovery portion.
I flew as FTE on the first explanatory flight in the L-29 where we performed Roller Coasters, Dynamic Wind-up-Turns and Split-S’s reaching up to 6.8g.