Flight Test Engineering
In the New Detachment at the Flight Test Center, from Homey airstrips, we provide a wide range of services dedicated to the Control, Performance and Security of aircrafts. In addition, we explore possible innovations in Aeronautics/Avionics and Aviation sector.
We also guarantee special hangars, in which maintenance is carried out, with the most advanced tools and personnel at the top of the line.
Below you can find everything about our Aircraft Testing, with a special focus on Military Aircrafts Testing.
AFTC Detachment 3
4th Street, Bld 412
89001 - Alamo, NV
Head of Aeronautical Engineering:
Eng. Francis Coleman
WIND TUNNEL TESTS
- Static Force and Moment
- Rotary Balance
- Captive Model
- Vertical Spin Tunnel
The results of wind tunnel tests are used, as part of the design and development process, to enhance confidence in theoretical estimates of the aircraft's aerodynamic characteristics. They are also used to refine predictions of the aircraft's flying qualities and performance and, when necessary, to guide modifications to the aircraft's external configuration or flight control system. Wind tunnel data are also the prime initial source for the aerodynamic data base required for a variety of analytical programs used in the design process, and for man-in-the-loop simulators.
- Iron Bird
- Hot Bench
- Avionics Simulators
- In Flight Simulators
Simulators are an essential element in the pre-flight test process. The engineer who builds and uses the simulator is generally the one who knows the most about the aircraft's characteristics. Simulators are used to assist the design process by enabling subsystems and systems to be operated in a representative, interactive manner, with or without the "man-in-the-loop, with relevant flight conditions and overall response, etc., being simulated via appropriate computer programs.
- Inlet Distortions
- Operability and Performance Testing
- Durability Testing
- Ice, Water and Bird Ingestion Testing
- Installed Thrust
Prior to the flight testing of new or modified propulsion systems, current accepted practice dictates that the system be subjected to several types of ground tests. In general, these include inlet testing, altitude operability and performance testing, durability testing, and installed thrust tests. The overall objectives of these tests are to measure the thrust of the engine, both uninstalled and installed; to assess the airflow distortion caused by the engine inlet; to evaluate engine operability, both with and without inlet distortion; and to evaluate the durability of the engine. These types of testing would normally occur after more developmental preliminary tests such as engine component structural and aero-mechanical tests such as compressors, fans, combustors, etc. (See Section 24 for a discussion of propulsion flight tests).
WEIGHT AND BALANCE TESTS
Weight and balance data is initially obtained by the airframe contractor through analytical "bookkeeping" techniques. The weight and location of each component of the aircraft is determined and stored into an analytical program that calculates total aircraft weight, moments of inertia, and centers of gravity based on the contribution of all the individual components.Total aircraft weight and balance characteristics can be accurately determined by this method if considerable care is taken in accounting for all individual
components. It is essential to also physically measure the aircraft's weight and balance characteristics to
obtain actual values of weight and center of gravity, and to provide a final check of the analytically predicted bookkeeping values.
The objective of these tests is to obtain the weight, centers of gravity, and moments of inertia of the aircraft. Weight and balance data should be obtained for various aircraft configurations, fuel loadings, and store loadings.
GROUND VIBRATION TESTS
A basic GVT consists of vibrating the aircraft at a number of different frequencies and measuring the response at various locations on the aircraft. Usually several hundred response stations are monitored in order to fully define the aircraft's modal characteristics. The response signals are processed through signal conditioning amplifiers and passed on to high speed computers for data manipulation and analysis.
Ground vibration testing (GVT) is an essential preliminary ground test that must be conducted prior to the beginning of flight testing. The objective of the GVT is to obtain aircraft structural mode characteristics such as frequencies, mode shapes and damping. It is done to verify and update the aircraft analytical flutter model as well as provide a means of identifying modes from the frequencies found in flight test data. A GVT is not only required for new aircraft designs but also when extensive changes are made to existing aircraft or when new store configurations are added.
AIRCRAFT EXTERNAL NOISE
STRUCTURAL LOAD TESTS
The structural loads ground testing is divided into two major categories: 1) static loads tests and 2) durability tests and are usually conducted on separate airframes. The static loads tests are conducted to ensure that the aircraft structure has adequate strength to withstand the anticipated operational loads. Durability tests are done to verify the fatigue life of the aircraft. Damage tolerance tests are often considered part of the durability tests and are done to verify that the aircraft has sufficient structural redundancy in the event of battle damage.
Structural loads ground testing is conducted on structural test airframes (usually a bare hull) and not on a flight article. This structural testing is not a simple "pre-flight" test as are most others in this Section, but is a parallel activity which continues, in respect to fatigue tests, often throughout the entire aircraft life. The objective of this testing is to verify the structural load capability of the aircraft.
GAIN MARGIN TESTS
VERIFICATION AND CALIBRATION TESTS
AIRDATA MEASURAMENT & CALIBRATION
TYPICAL TEST MANEUVERS
- Symmetrical Maneuvers
- Rolling Maneuvers
- Yawing Maneuvers
FAILURE CONDITIONS: Some failure conditions, e.g., trim runaways, engine failure conditions, or inadvertent thrust reverser deployment, may also be critical. Caution is strongly recommended when these conditions are simulated in-flight.
The objective of these tests is to provide a flight envelope that will allow the pilot/flight crew to safely
utilize the full design capabilities of the aircraft. This prime objective must continuously be kept in mind
while setting up the various specific tests such as determining stresses that exist on various critical parts of
the structure under a given set of airspeed, altitude, Mach number, and normal acceleration.
TAKE OFF AND LANDING TESTS
STABILITY AND CONTROL TESTS
- Trimmed flight
- Pitch doublet
- Slow acceleration/deceleration (accel/decel) using longitudinal control
- Wind-up turn
- Steady heading sideslip
- Yaw doublet
- Roll doublet
- Bank to bank roll
HIGH ANGLE OF ATTACK TESTS
UNDERCARRIAGE, WHEELS AND BRAKES
TESTING UNDER ENVIRONMENTAL EXTREMES
The general objective of all-weather testing is to determine to what extent a weapon system, including its essential support equipment, maintenance personnel and aircrews can accomplish the design mission in world-wide climatic extremes. Specific objectives include evaluation of the effects of the particular environment on the integrated system, initiation of corrective actions (including design changes and problem work-around procedures), assessing operational impacts such as system effectiveness, safety, and operating/maintenance costs, and initiation of changes at an early stage in the production of the weapon system.
Climatic tests of US Air Force systems and equipment are accomplished first in the McKinley Climatic Laboratory at Eglin AFB, FL. The Laboratory is a large hangar in which the complete aircraft can be tested, with or without the engines running. (An abbreviated description of this laboratory is contained in reference 18-1. Detailed descriptions are contained in references 11 and 12 of reference 18-1). As noted in reference 18-1, the United Kingdom also has a climatic laboratory. In most other countries, artificially controlled conditions are usually limited to equipment testing and qualification. The aircraft themselves are usually tested in natural environments.
RADAR CROSS SECTION / ANTENNA RADIATION PATTERNS
logistics tests and evaluation
ARMAMENT TESTING AND STORES SEPARATION
The aircraft is specially instrumented to record accelerations and strains at critical locations on the aircraft structure and stores. A safe envelope is determined by flight testing at increasing dynamic pressures and Mach numbers. After stabilizing at a test condition, the aircraft is forced to respond at the primary structural frequencies. This force may be imparted by a control surface impulse or an on-board exciter system. Frequency and damping values are then determined for the primary modes. These values are tracked throughout the envelope in real-time. By identifying lightly damped or rapidly decaying modes, testing can be terminated before the aircraft flutters. Real-time and post mission data reduction consists of fast Fourier transforms to measure the aircraft structural response and damping levels.
AIRCRAFT AND STORE LOADS
Aircraft and store load testing is necessary to verify structural integrity and to determine if the aircraft and store suspension system can safely carry the store with the store induced loads. The aircraft (with stores loaded) is flown at 80- and 100-percent design limit loadings throughout the flight envelope. This standard Captive Flight Profile is defined in MIL-STD-1763A and includes a speed soak, throttle chops, wind up turns, etc. When analysis of specific aircraft/store combinations indicates that design limits will be exceeded for certain flight conditions, real-time loads flight testing is required to determine safe carriage limits. The aircraft and store are instrumented to record rates and accelerations, shear, bending moment, torsion, stress, and pressure at specific aircraft locations. Analysis consists of determining the loads encountered at the known conditions, comparing these to those predicted and ensuring that no damage occurred to the aircraft.
STABILITY AND CONTROL
Large masses alter aircraft center of gravity and altered airflow can impact stability and control. Thus the aircraft handling tests described in Section 15 must be conducted to determine if the aircraft's stability and control characteristics remain satisfactory when carrying all required external stores configurations. The test configurations are selected, depending on the aspect under investigation, to give the worst cases in terms of mass, drag, pitch or roll inertia, etc. To keep the tests within economic bounds, analogies may be drawn between similar stores, and extensive use made of appropriate computer models/simulations. The aircraft is loaded with the desired stores and the pilot maneuvers the test aircraft inducing steady-state sideslip, pitch doublets, rolls, wind-up turns, high and low speed runs, accelerations, and refueling. The outputs of the testing consist of the aircraft response to perturbation inputs (number of overshoots), stick force per 'g' encountered and a qualitative pilot evaluation. Analysis consists of a comparison to stability without the stores present and to specification criteria.
SOFTWARE TEST AND EVALUATION
Because software has no physical manifestation, it cannot be tested directly by physical means although, in principle, the functions of a system controlled by that software certainly can. Unfortunately, for all but the very simplest of systems, the time required to test the full set of functions with all possible combinations of inputs would be utterly impracticable, even if the testing were to be conducted using the fastest available computers to simulate the various inputs. It might be argued that where the code is both simple and non-safety-critical, empirical testing is adequate. This approach has been widely accepted (even when the code was far from simple), but it may well come to be considered indefensible. Software executed by a digital computer is discontinuous by its very nature, and thus interpolation between test points is not valid unless the response of the system has been proved to be quasi-continuous: however, the number of input conditions is usually so great that this cannot be proved by empirical means. Thus, software is better tested using the non-physical techniques discussed below.