Characteristics Supermaneuverability

1 characteristics

1.1 post-stall characteristics
1.2 thrust-to-weight ratio
1.3 high aerodynamic maneuverability
1.4 canard controls
1.5 thrust vectoring

characteristics

although aforementioned no fixed set of features defines supermaneuverable aircraft explicitly, virtually aircraft considered supermaneuverable have majority of common characteristics aid in maneuverability , stall control.

post-stall characteristics

the key difference between pure aerodynamic fighter , supermaneuverable 1 found in post-stall characteristics. stall, aforementioned, happens when flow of air on top of wing becomes separated due high angle of attack (this can caused low speed, direct cause based on direction of airflow contacting wing); airfoil loses main source of lift , not support aircraft until normal airflow restored on top of wing.

a su-27 russian knights aerobatic team, supermaneuverable 4th-generation jet. jet can perform pugachev s cobra.

the behavior of aircraft in stall main difference can observed between aerodynamic maneuverability , supermaneuverability. in stall, traditional control surfaces, ailerons, have little or no ability change aircraft s attitude. aircraft designed stable , recoverable in such situation; aircraft pitch nose-down angle of attack of wings reduced match aircraft s current direction (known technically velocity vector), restoring normal airflow on wings , control surfaces , enabling controlled flight. however, aircraft deep stall; aircraft s design inhibit or prevent reduction in angle of attack restore airflow. f-16 has flaw, due in part fly-by-wire controls, under circumstances limit ability of pilot point nose of aircraft downward reduce angle of attack , recover. neither extreme pitch-down nor deep stall desirable in supermaneuverable aircraft.

a supermaneuverable aircraft allows pilot maintain @ least control when aircraft stalls, , regain full control quickly. achieved largely designing aircraft highly maneuverable, not deep stall (thus allowing quick recovery pilot) , recover predictably , favorably (ideally level flight; more realistically shallow nose-down attitude possible). design, features added allow pilot actively control aircraft while in stall, , retain or regain forward level flight in extremely shallow band of altitude surpasses capabilities of pure aerodynamic maneuvering.

thrust-to-weight ratio

a key feature of supermaneuvering fighters high thrust-to-weight ratio; is, comparison of force produced engines aircraft s weight, force of gravity on aircraft. desirable in aerobatic aircraft, high-thrust-to-weight ratio allows aircraft recover velocity after high-g maneuver. in particular, thrust-to-weight ratio greater 1:1 critical threshold, allows aircraft maintain , gain velocity in nose-up attitude; such climb based on sheer engine power, without lift provided wings counter gravity, , has become crucial aerobatic maneuvers in vertical (which in turn essential air combat).

high thrust-to-weight essential supermaneuvering fighters because not avoids many situations in aircraft can stall (such during vertical climbing maneuvers), when aircraft stall, high thrust-to-weight ratio allows pilot sharply increase forward speed aircraft pitches nose-down; reduces angle nose must pitch down in order meet velocity vector, recovering more stall. allows stalls controlled; pilot intentionally stall aircraft hard maneuver, recover high engine power.

beginning in late fourth-generation , through generation 4.5 of aircraft development, advances in engine efficiency , power enabled many fighters approach , exceed thrust-to-weight ratios of 1:1. current , planned fifth-generation fighters exceed threshold.

high aerodynamic maneuverability

even though true supermaneuverability lies outside realm of possible pure aerodynamic control, technologies push aircraft supermanuvering capability based on otherwise conventional aerodynamically controlled design. thus, design highly maneuverable traditional aerodynamics necessary base supermaneuverable fighter. features such large control surfaces provide more force less angular change neutral minimizes separation of airflow, lifting body design including use of strakes, allow fuselage of aircraft create lift in addition of wings, , low-drag design, particularly reducing drag @ leading edges of aircraft such nose cone, wings , engine intake ducts, essential creating highly maneuverable aircraft.

some designs, f-16 (which in current production form regarded highly maneuverable, f-16 vista tech demonstrator considered supermaneuverable) designed inherently unstable; is, aircraft, if uncontrolled, not tend return level, stable flight after disturbance inherently stable design will. such designs require use of fly-by-wire system computer corrects minor instabilities while interpreting pilot s input , manipulating control surfaces produce desired behavior without inducing loss of control. corrected for, instability of design creates aircraft highly maneuverable; free self-limiting resistance stable design provides desired maneuvers, intentionally unstable design capable of far higher rates of turn otherwise possible.

canard controls


the f-15 active in flight; design modified f-15 eagle vectored thrust , canards.

a canard elevator control surface placed forward of wings. sometimes, b-1b, used stabilize flexible portions of fuselage or provide minute attitude changes, used supplement or full replacement of tail-mounted stabilators.

the theory behind canards sole elevator surface no elevator configuration aft of wings satisfactory maneuvering purposes; airflow on wings creates turbulence, small, , affects elevators placed directly behind wings. placement below wings (common on many fighters) exposes elevators greater turbulence under-wing ordnance. original solution such problems, t-tail, has been largely discredited being prone dangerous deep stalls . other solutions v-tail place combination rudder-elevator surfaces out of wings airflow, reduce effectiveness of control surface in pure pitch , yaw axes.

as supplement traditional elevators, canards vastly increase control surface area, , increase critical angle of attack of wings canard directs air more directly toward leading edge of wing. can designed operate independently (i.e. counter-rotate), acting ailerons.

canards not requirement, , can have disadvantages including reduced pilot visibility, increased mechanical complexity , fragility, , increased radar signature. f-22, example, not incorporate canards, stealth reasons. production su-35 omits canards. many technology demonstrators , maneuverability testbeds such f-15 s/mtd incorporated canards, when production aircraft based on did not. production fighters eurofighter typhoon, dassault rafale , saab gripen use delta-wing configuration canard surfaces, while variants of su-27 including su-30, su-30mki, su-33 , su-37 use canards supplement traditional tail-mounted elevators.

thrust vectoring


the rockwell-mbb x-31, experimental supermaneuverable aircraft incorporating thrust vectoring

though high thrust-to-weight ratio , high aerodynamic maneuverability found on both aerodynamic , supermaneuvering aircraft, technology directly linked supermaneuverability thrust vectoring, in geometry of exhaust nozzle of traditional jet engine can modified angle engine s thrust in direction other directly rear (i.e., upwards or downwards). applies force rear of aircraft in opposite direction similar conventional control surface, unlike control surface force vectored thrust dependent on current engine thrust, not airspeed; thrust vectoring not augments control surfaces (generally of elevators) @ speed, allows aircraft retain maximum maneuverability below corner speed , attitude control below stall speed while in maneuvers. technology demonstrators such x-31, f-16 vista , f-15 s/mtd built showcase capabilities of aircraft using technology; has since been incorporated pre-production , production fighters such f-22 raptor. eastern bloc design companies have introduced technology variants of fourth-generation aircraft such mig-29 , su-27 produce mig-29ovt tech demonstrator , su-30mki air superiority fighter respectively, , planned fifth-generation russian-designed aircraft such sukhoi su-57 use technology well. in addition domestic russian su-30 fighters upgraded thrust vectoring engines.

thrust vectoring useful while performing maneuvers such aerial j-turn, nose of aircraft pointed upwards (and engine thrust counters gravity providing attitude control). considered impossible, in fact, perform true j-turn maneuver without vectored thrust. other maneuvers considered impossible perform under control using aerodynamic maneuvering include bell (a 360° loop negligible altitude change) , controlled flat spin (360° of yaw around point of rotation lies inside aircraft).