Engineering topics

Andrisani, D., II

Publications and source records attributed to Andrisani, D., II.

7 records

NASA NTRS1979

Gust alleviation using direct turbulence measurements

The research reported upon in this paper describes an effective method of gust alleviation using direct measurements of atmospheric turbulence to drive the aircraft control surfaces in a way that attempts to directly counter or cancel those forces and moments produced on the aircraft by gusts. The method yields a feedforward or open loop control law, simple to mechanize and relatively insensitive to changes in flight condition. When applied directly, the resulting control law effectively gust-alleviates in the low frequency phugoid and short period range but has a tendency to amplify structural mode vehicle motions due to the phase lag of the actuators. A method of design based upon the use of a diagonal or Jordan form of the equations of motion enables the designer to avoid this problem of structural mode excitation.

Rynaski, E. G.↗

NASA NTRS1978

The Total In-Flight Simulator (TIFS) aerodynamics and systems: Description and analysis

The aerodynamics, control system, instrumentation complement and recording system of the USAF Total In/Flight Simulator (TIFS) airplane are described. A control system that would allow the ailerons to be operated collectively, as well as, differentially to entrance the ability of the vehicle to perform the dual function of maneuver load control and gust alleviation is emphasized. Mathematical prediction of the rigid body and the flexible equations of longitudinal motion using the level 2.01 FLEXSTAB program are included along with a definition of the vehicle geometry, the mass and stiffness distribution, the calculated mode frequencies and mode shapes, and the resulting aerodynamic equations of motion of the flexible vehicle. A complete description of the control and instrumentation system of the aircraft is presented, including analysis, ground test and flight data comparisons of the performance and bandwidth of the aerodynamic surface servos. Proposed modification for improved performance of the servos are also presented.

Andrisani, D., II↗

NASA NTRS1978

Identification of the stability parameters of an aeroelastic airplane

The problem of the parameter identification of large scale dynamic systems involving a system matrix characterized by approximately 200 elements is addressed. By using phase variable transformations, a mathematical model of an aeroelastic airplane is described in a form that is amenable to partial or piecemeal acceptance of parameters estimated from flight data. A mathematical model of the U.S. Air Force Total In-Flight Simulator was computed using the FLEXSTAB digital computer program. As data became available during the progress of the flight test program, this data was processed and substituted in the mathematical model for parameters analytically obtained from the FLEXSTAB program. The results tend to show a progressive and orderly transition from an analytically defined mathematical model to one obtained from the flight tests of the actual aircraft.

Rynaski, E. G.↗

NASA NTRS1978

Identification of the stability parameters of an aeroelastic airplane

Phase variable transformations are used to construct the mathematical model of an aeroelastic aircraft in a form that is amenable to partial or piecemeal acceptance of parameters estimated from flight data. The problem is one of parameter identification of large scale dynamic systems involving a system matrix characterized by about 200 elements. A mathematical model of the USAF Total In-Flight Simulator was computed using the FLEXSTAB program. As data became available during the progress of the flight test program, it was processed and substituted in the mathematical model for parameters obtained from the FLEXSTAB program. Results tend to show a progressive and orderly transition from an analytically defined mathematical model to one obtained from the flight tests of the actual aircraft.

Rynaski, E. G.↗

NASA NTRS1975

A study for active control research and validation using the Total In-Flight Simulator (TIFS) aircraft

The results of a feasibility study and preliminary design for active control research and validation using the Total In-Flight Simulator (TIFS) aircraft are documented. Active control functions which can be demonstrated on the TIFS aircraft and the cost of preparing, equipping, and operating the TIFS aircraft for active control technology development are determined. It is shown that the TIFS aircraft is as a suitable test bed for inflight research and validation of many ACT concepts.

Chen, R. T. N.↗

NASA NTRS1973

Full-scale wind-tunnel investigation of effects of slot spoilers on the aerodynamic characteristics of a light twin-engine airplane

A wind-tunnel investigation has been conducted to determine the effects of slot spoilers on the longitudinal and lateral aerodynamic characteristics of a full-scale mockup of a light twin-engine airplane. The slots were located along the leading edge of the flaps and were used to modulate the flap-induced lift as a possible means of achieving direct lift control. The data showed that the slots were effective in spoiling up to 61 percent of the flap-induced lift, but that an adverse pitching-moment change (nose up) accompanied opening the slots. Opening the slots was found to decrease slightly the downwash angle at the tail and to increase slightly the longitudinal stability of the model.

Verstynen, H. A., Jr.↗

NASA NTRS1972

Wind tunnel study of slot spoilers for direct lift control

An investigation was conducted in a 300-mph 7- by 10- foot tunnel to obtain data for a slot spoiler direct lift control system. Slot spoilers are believed to have advantages over flap-type direct lift control (DLC) systems because of the small amount of power required for actuation. These tests, run at a Reynolds number of 1,400,000 showed that up to 78 percent of the lift due to flap deflection could be spoiled by opening several spanwise slots within the flaps. For a given lift change the drag change was significantly less than that which would be obtained by a variable flap DLC system. A nozzle-shaped slot was the most effective of the slot shapes tested.

Andrisani, D., II↗