outline of course: introduction takeoff landing range & endurance cruise performance elements of...

Outline of Course:

Introduction

Takeoff

Landing

Range & Endurance

Cruise Performance

Elements of Aircraft Control & Navigation

High-Speed Aircraft

AER 615 Aircraft Performance

Boeing Sonic Cruiser (Mach 0.98 at cruise),cancelled Dec. 2002; marginally shorter triptimes did not compensate for poorer fuel economy(hence, higher passenger ticket prices would havebeen required, viz. Concorde)

Flight envelope for fixed- and rotary-winged flight vehicles using differing means for their propulsion. Quantitatively, to give some scale to the above diagram, the upper flight Mach number for turboshaft powered helicopters in forward level flight is around 0.4, piston engine propellered airplanes in steady level flight is around 0.6, for turboprop airplanes around 0.7, for high-bypass turbofan powered airplanes around 0.9, low-bypass turbofan and turbojet powered airplanes around 3.0, for ramjet powered aircraft around 5.0, for scramjet powered aircraft around 10.0, and for non-airbreathing chemical rocket powered vehicles, up to and beyond orbital flight Mach numbers (20.0 and higher). Due to aerodynamic structural loading and aeroheating, one needs to go higher in altitude as one goes faster (conditions less severe at lower air density). Of course, on the other hand in going very high in altitude, one needs sufficient air intake if one is using air-breathing engines (combustion requirement), in addition to needing sufficient air density for aerodynamic lift at a given airspeed. Graph reprinted with permission of the American Institute of Aeronautics and Astronautics.

A bow shock wave exists for free-stream Mach numbers above 1.0

Wing sweep to reduce wave drag (pressure drag due to compression wave presence)

Swing-wing to modify lift & drag at different flight Mach numbers

Area rule, applied to slimming or necking down a portion ofthe aft fuselage, relative to the amount of wing volumeoutboard from the fuselage location, to reduce wave drag

Base drag coeff. referenced to max. body cross-sectional area

D =(1/2) V2A Cd = 0.7 p Ma2 A Cd

Lift-to-drag as an important issue

Sonic boom as an important issue

)W

W(n

C

C

TSFC

V

gR

fin

ini

D

L 1

D

L

C

C

TSFC

Maa

Breguet range equation for jet aircraft:

Bell X-1, liquid-rocket powered; first level supersonic fixed-wing aircraft flight, 1947

North American YF-100 Super Sabre prototype,employing swept wing to lower drag; first levelsupersonic jet flight, 1953, reaching Mach 1.1 usingair-breathing turbojet engine

First supersonic bomber, Convair B-58A Hustler, reached Mach 2 in1957; note the “area rule” beingapplied as one moves down the fuselage, to minimizesupersonic wave drag

First Russian supersonic bomber,Tupolev Tu-22 Blinder, circa 1961

North American XB-70A Valkyrie supersonic bomber, 1965;only 2 prototypes were built; Mach 3 capability

XB-70A, circa 1968

Rolls-Royce/SNECMA Olympus 593 turbojet(powered the Concorde)

Concorde

Concorde cruised at Mach 2.04 (1350 mph) for bestfuel economy (supercruise, i.e., without use of afterburner;cruise altitude ranged from 45000 to 60000 ft, withdesign altitude of 56000 ft)

Circa 1972

In order to minimize the wave drag encountered in transonic/supersonic flight, the curvature of the supersonic aircraft’s airframe should be kept to a minimum, which implies much higher fineness ratios (length-to-width), hence “long & skinny”. This is why high-speed aircraft have long pointed noses and tails, and cockpit canopies that are flush to the fuselage line.

Aerodynamic heating of the aircraft’s external structure becomes an issue above a flight Mach number of around 2.5, and leads to flying at higher altitudes (lower air densities and temperatures) to avoid overheating.

The sonic boom emanating from a supersonic aircraft’s airframe restricts the paths that the aircraft is allowed to fly, when over populated ground and below the noise threshold altitude for the airplane. Another reason to fly higher.

Design Issues

Final flight of Concorde was in 2003

Schematic diagram of an engine intake for the Aérospatiale/British Aircraft Corporation Concorde airliner, with the internal variable geometry (doors, valves, etc.) set up for supersonic-cruise flight

Tupolev Tu-144 supersonic transport; firstprototype flew in 1968, and enteredin service in varying roles from 1975 to 1985;Mach 2 capability, but less fuel efficient thanthe Concorde; 16 were built

Boeing 2707 (SST; supersonic transport);proposed but never built (1971 cancellation)

Boeing 2707-300 (final fixed-wing variant;earlier proposals had a swing-wing)

SR-71

J58

Lockheed SR-71 Blackbird, Mach 3.3at 80000 ft capability (limited in part bymaximum allowable aerodynamic heatingof airframe); first flight 1964

SR-71 engines:P&W J58 ,turboramjet

Tupolev Tu-444 supersonic business jet, proposed

Supersonic Aerospace Intl. Quiet Supersonic Transport(QSST) business jet, proposed

HyperMach Aerospace SonicStarsupersonic business jet (Mach 4),proposed

Anticipated flight envelope, altitude vs. flight Mach number, for commercial supersonic and hypersonic flight vehicle operations. Sonic boom limits for sound pressure waves reaching the ground are also indicated. Graph from a McDonnell Douglas study, circa 1970s.

Anticipated flight envelope, altitude vs. flight Mach number, for commercial supersonic and hypersonic flight vehicle operations. The smaller closed envelope is for the Falcon HTV-3X (“Blackswift”) hypersonic technology demonstrator under study by Lockheed Martin and DARPA. The larger unclosed envelope (corridor), below the SpaceShuttle’s ascent/descent flight performance limits, is for future hypersonic vehicles with capabilities superseding those of the TBCC-powered HTV-3X. The right diagram is an artist’s conception of a possible HTV-3 variant. Courtesy of DARPA.

Airbus A2, hydrogen-fuelledhypersonic airliner, proposed;Mach 8 cruise; using Scimitarturbine-based combined-cycle(TBCC) engine, proposed

NASA X-30 for National Aerospaceplane (NASP) program;program circa 1980s, eventually cancelled in 1994

Powered by two AerojetStrutjet RBCC engines

X-30 objectives, for NASP development

NASA X-43 Hyper-X,using scramjet engine,for Mach 7 to 10 cruise;subscale prototype,unmanned

Artist concept of DARPA’s Aurora recon a/c,Mach 5 cruise, using scramjet engine

Circa 1985

SSTO = singlestage to orbit

HOTOL = horiz.takeoff/landing

Skylon SSTO flight vehicle, on the tarmac

Synergic airbreathing rocket-based (SABRE) combined-cycle engine for Skylon SSTO vehicle, using cooled-air cycle engine (CACE) approach

Skylon vehicle in orbit, preparing to deploy satellite from payload bay into orbit