High performance aircraft are, by their very nature, often required to undergo maneuvers involving high angles of attack. Under these conditions unsteady vortices emanating from the wing and the fuselage will impinge on the twin fins (required for directional stability) causing excessive buffet loads, in some circumstances, to be applied to the aircraft. These loads result in oscillatory stresses, which may cause significant amounts of fatigue damage. Active control is a possible solution to this important problem. A full-scale test was carried out on an F/A-18 fuselage and fins using piezoceramic actuators to control the vibrations. Buffet loads were simulated using very powerful electromagnetic shakers. The first phase of this test was concerned with the open loop system identification whereas the second stage involved implementing linear time invariant control laws. This paper looks at some of the problems encountered as well as the corresponding solutions and some results. It is expected that flight trials of a similar control system to alleviate buffet will occur as early as 2001.
[1]
Tg Ryall.
Digital Control of an Experimental Flutter Model
,
1990
.
[2]
E. Crawley,et al.
Use of piezoelectric actuators as elements of intelligent structures
,
1987
.
[3]
Vladimír Kucera.
Optimal control: Linear quadratic methods: Brian D. O. Anderson and John B. Moore
,
1992,
Autom..
[4]
H. Ashley,et al.
Active Control for Fin Buffet Alleviation
,
1993
.
[5]
W Moses Robert,et al.
Active Vertical Tail Buffeting Alleviation on a Twin-Tail Fighter Configuration in a Wind Tunnel
,
1997
.
[6]
Lennart Ljung,et al.
System Identification: Theory for the User
,
1987
.
[7]
Robert W. Moses,et al.
Vertical-tail-buffeting alleviation using piezoelectric actuators: some results of the actively controlled response of buffet-affected tails (ACROBAT) program
,
1997,
Smart Structures.