EJECTION SEAT
121
9. EJECTION SEAT CAPABILITIES TO MEET
AGILE AIRCRAFT REQUIREMENTS
Larry Specker
John Plaga
Air Force Research Laboratory
AFRL/HEPA
2800 Q Street, Bldg #824
Wright-Patterson AFB, OH 45433-7947, U.S.A.
Vic Santi
Aeronautical Systems Center
ASC/ENFC
2530 Loop Road West
Wright-Patterson AFB, OH 45433-5797, U.S.A.
9.1 BACKGROUND
Current USAF seats provide safe aircrew escape up to about 425 Knots Equivalent AirSpeed (KEAS). The performance limit of US ejection seats is cited as 600 KEAS, but very few successful ejections have occurred over 500
KEAS. Windblast is a cause of major injuries and fatalities at airspeeds above 425 KEAS. Adverse aircraft altitude, attitude, and roll rates are also known to degrade survival probability.
Aircraft Sideslip vs Airspeed (notional)
16
14
Sideslip (Deg)
Advanced, highly-maneuverable aircraft are expected to make increasing demands on initial off-axis conditions with which ejection systems must contend.
A notional representation of current aircraft sideslip capabilities is shown in Figure 9.1.
12
10
As aircraft become more agile using
8
advanced flight control systems and thrust
6
vectoring features, the area above this curve
4
will become more of a concern. Experience with aircraft such as the F-16 and F-22 that
2
have a relatively large canopy profile and
0
axial length has already highlighted a number
0
100
200
300
400
500
600
700 of structural concerns. In these aircraft, the
Airspeed (KEAS) lateral moment on the canopy during jettison in sideslip conditions can cause extremely
Figure 9.1 Airspeed vs Sideslip Angle for Notional Aircraft high loads in the aft hinge areas. In a typical design, failures in this area can result in an unguided canopy jettison and potential for impacts with the pilot. Escape system designs with a canopy-attached seat initiation lanyard must also contend with adverse lanyard pull angles and the possibility of the lanyard itself
9. EJECTION SEAT CAPABILITIES TO MEET
AGILE AIRCRAFT REQUIREMENTS
Larry Specker
John Plaga
Air Force Research Laboratory
AFRL/HEPA
2800 Q Street, Bldg #824
Wright-Patterson AFB, OH 45433-7947, U.S.A.
Vic Santi
Aeronautical Systems Center
ASC/ENFC
2530 Loop Road West
Wright-Patterson AFB, OH 45433-5797, U.S.A.
9.1 BACKGROUND
Current USAF seats provide safe aircrew escape up to about 425 Knots Equivalent AirSpeed (KEAS). The performance limit of US ejection seats is cited as 600 KEAS, but very few successful ejections have occurred over 500
KEAS. Windblast is a cause of major injuries and fatalities at airspeeds above 425 KEAS. Adverse aircraft altitude, attitude, and roll rates are also known to degrade survival probability.
Aircraft Sideslip vs Airspeed (notional)
16
14
Sideslip (Deg)
Advanced, highly-maneuverable aircraft are expected to make increasing demands on initial off-axis conditions with which ejection systems must contend.
A notional representation of current aircraft sideslip capabilities is shown in Figure 9.1.
12
10
As aircraft become more agile using
8
advanced flight control systems and thrust
6
vectoring features, the area above this curve
4
will become more of a concern. Experience with aircraft such as the F-16 and F-22 that
2
have a relatively large canopy profile and
0
axial length has already highlighted a number
0
100
200
300
400
500
600
700 of structural concerns. In these aircraft, the
Airspeed (KEAS) lateral moment on the canopy during jettison in sideslip conditions can cause extremely
Figure 9.1 Airspeed vs Sideslip Angle for Notional Aircraft high loads in the aft hinge areas. In a typical design, failures in this area can result in an unguided canopy jettison and potential for impacts with the pilot. Escape system designs with a canopy-attached seat initiation lanyard must also contend with adverse lanyard pull angles and the possibility of the lanyard itself
References: “ACES II, Advanced Concept Ejection Seat,” McDonnell Douglas Information Brochure, McDonnell Douglas Aerospace, St Louis, Missouri, 1993. Hall, Justin, The Vibration Environment of an Ejection: Lessons Learned from the Fourth Generation Escape Systems Advanced Technology Demonstration Program, Paper presented at SAFE Symposium, 1998. Requirements for Adult Size Small Female and Large Male Dummies.” Proceedings of the International Congress and Exposition., SAE Technical Paper Number 890756, 1989. Severin, G. I., J. W., Rabinovitch, B. A., Specker, L. J., et al, “Foreign Comparative Testing, Test and Evaluation of the K-36D Ejection Seat, Test Reports: Volumes I-IV,” RD & PE Zvezda Design Bureau, Tomilio, Russia, 1993. Wheeler, Craig M.; Niedzielski, Paul; Barnette, Bill; McDonald, A. Blair; Fourth Generation Escape System Technology Demonstration Pintle Nozzle Controllable Propulsion System, Paper presented at SAFE Symposium, 1998.