A day-off and a wonderful Easter in Canada spent with the big Greek family. So proud to be Greek…
A paper and a presentation are going to be given in the SETP/SFTE European Symposium in Luleå, Sweden from 15th to 18th of June 2014. A visit to the Swedish Weapon Testing Range is also scheduled.
The paper’s title is “Testing Together in a Flight Test Training Environment” with myself as first author and at least one more author from the Aerospace Industry. Part of the paper is dealing with Su-30MKM E-M flight tests recently performed by ITPS students.
Another great opportunity to keep up with the industry’s progress, meet some European friends and of course visit Sweden during summertime :-)
The Aero L-39 Albatros is a high-performance jet trainer aircraft developed in Czechoslovakia. Part of the current course is based on this aircraft, while various upgrades are discussed to be implemented. “Family photo” below.
Can’t wait to fly it.
Variable Stability Systems (VSS) or later known as In-flight simulators are aircraft capable of establishing various stability characteristics by modifying the gains in their control laws. These aircraft serve research, training and evaluation purposes and have been flying for over half a century. The most modern and advanced VSS is the F-16 VISTA currently operated by USAF TPS at Edwards which establishes 5 DOF while its initial design proposal was for 6 DOF (see the very interesting initial design below, which included side-force surfaces on the wings as well as split drag petals on the wing tips).
Today, the availability and “integrability” of the various FCS parts can make a low cost VSS project feasible. Following a request, a preliminary analysis on such a project was conducted determining the required project phases and the basic specifications of each VSS part. This still remains work in progress, however more details cannot be released.
In many performance analyses, the calculation of Mach number is required as a function of Vc (calibrated airspeed) and Hp (pressure altitude). While flight test textbooks include all the analysis steps in form of mathematical formulas, for this specific step the use of a chart is recommended. See below chart as given by USN TPS performance manual:
The problem with this chart, as with all similar charts is that it does not provide the student or analyst a convenient way to get high accuracy values of Mach number, and it can not be easily automated or implemented in a code, let alone the process of trying to draw straight lines on a paper or screen. In other words, its not an optimum engineering approach.
Before trying to approximate graphically the drawn curves with equations, going back to basics and using the basic thermodynamic laws, the standard atmosphere relations and the instrument correction equations, the following formula was derived.
where assl is the standard speed of sound at sea level. The derivation process is found in the attached images below.
A quick superposition of the derived equation over the given chart shows that it provides a good approximation, but not a perfectly accurate agreement. (In the plot below, the color lines are the lines coming from the derived equation for the various altitudes).
This finding was encouraging, but also confusing. In order to cross-check the validity of the equation, it was compared to an other similar chart of M, Vc, Hp found in a technical paper. The agreement with those published charts was the found to be excellent.
1. Always try to use equations rather than graphical charts, if not provided, try to derive them. Many times, the textbook editor just recycles information without deeper examination.
2. Many graphs are drawn “by hand” rather than by analytic curves. Be aware as this can mesh up your data!
In the process of upgrading a telemetry room… Having done the initial setup, the MATLAB real-time plotting codes are removed and replaced by a dedicated real-time display and analysis package used by the major aircraft manufacturers and the biggest training establishments. For the time being data servers, clients and operator consoles are being connected to the F16 simulator and hopefully to some manned and unmanned aircraft in the near future.
Two busy weeks on aircraft performance, lecturing on Gas Properties, Standard Atmosphere, Air Data, Pressure Error Corrections, Stalls, Take-off and Landing performance, Cruise performance, Climb performance, Maneuverability and Excess Power were completed successfully. Hard work for the students and the instructors as well.
Flights demonstrating PEC FTT have started with tower fly by’s. Jets are expected to kick-in in a month’s time.