The BLACKBIRD,

revisited in BLACKSBURG.

Presented by:

Pedro De Oliveira

Michael Libeau

on April 21, 2000.

Motivation for the project

• American intelligence forecasted U-2 vulnerability– Subsonic cruise speed

– 70 kft ceiling

– 1750 nm range

• Improved Russian missile technology plotted (SAM’s)

• U-2 being shot down on May 1, 1960 over U.R.S.S. reinforced the idea

• Government asked for a new aircraft– low radar cross-section aircraft

– Mach 3+ cruising speed (continuous!)

– altitudes in excess of 80 kft.

One idea… The SUNTAN Project

[Jenkins], p. 6

Another idea...Project Oxcart - Archangel II

[Jenkins], p. 7

A12 - the definitive idea

[Whitford], p. 188

The U2 and the SR-71

Drendel p 36

The several versions

Drendel 8

SR-71A General Data• Primary function: Strategic Reconnaissance

• Wing span = 55 ft 7in (16.942 m)

• Length = 107 ft, 5 in (32.741 m)

• GTOW = 140,000 lbf (63,500 kgf)

• Engine@Thrust = 2 J58@32,500 lbf (65,000 lbf SLST)

• Max speed = Mach 3.31 (World record speed)

• Rate of Climb = 10,000+ fpm

• Ceiling = 85,069 ft (also a World record)

• Range = 2,982 nm at Mach 3, 74,740 ft, on internal fuel

• Endurance on internal fuel, at loiter speed= 7h,

• At above range 1h20min over target area

• Manufacturer: Lockheed (McNamara ordered tooling destroyed)

Speed Comparison(“faster than a rifle bullet”)

• Mig-25 engines reported being destroyed after flying at 3.2M. Unofficial maximum speed was 2.8M

• XB-70 only dashed at 3.2M - most of the flight was subsonic.

• The SR-71 used to fly at 3.0M+ for hours.

Thrust-to-Weight Ratio Comparison

• The Mig-25 fuselage has a much smaller fineness ratio.

Jane’s, 74/75

Wing-Loading Comparison

More on T/W x W/S Comparison

XB-70Concorde

SR-71

MIG-25

[Whitford], p. 39

Wing Geometry ComparisonSpeed increase demands thinner wings.

[Whitford], p. 30

Speed increase also demands larger turn radii.

[Jenkins], p. 93

Aerodynamic ConsiderationsAnother application of the KISS methodology

• High fineness ratio bodies

• Highly swept double-delta wing.

[Whitford], p. 188

Aerodynamic Considerations - FUSELAGE

• High fineness ratio for minimum wave drag• Use of chines:

– better directional stability: reduction of the side-force

– offset the backward movement of the A.C. with Mach number

[Whitford], p. 150[Whitford], p. 150

Aerodynamic Considerations - WING

• Double-delta plan form allows high (t/c) ratio to minimize wave drag

• Swept keeps most of the wing in Mach cone :– For Mach 3.0 flight

– SR-71 wing sweep angle:

• Conical camber– moves the center of lift inboard

– relieves loading on engine nacelle structure due to outboard wing

– reduction in high rolling moment due to sideslip inherent to highly swept wings

)1

(sin90 1

Mcone−−ϒ=Λ

ϒ=Λ 5.70cone

ϒ=Λ 60LE

[Whitford], p. 188

Aero Considerations - VERTICAL TAILS

• All moving tails (+20/-20 deg)

• Cant angle to – reduce induced rolling moment when r ≠ 0

– stay on the correct side of the vortices shed by the nacelles - reduced VT deflection at low speed with ≠ 0

Whitford, p. 195

Vortices - I

Crickmore p 66

Vortices - II

Crickmore p 181

The all-moving VTs.

Drendel p 20Crickmore p 44

Stable or unstable?

Drendel p 45

YF-12 needed improved directional stability

Drendel p 12 Drendel p 17

Fins must fold for landing.

Drendel p 15

Aero Considerations - Aerodynamic Heating

• The SR-71, a hot airplane:– 600 F at nose (aerodynamic heating at Mach 3+)

– 520 F at the windshield glass

– 1200 F at the exhaust nozzle (fuel burned)

• 93% of the structural weight built of Titanium alloys

• Cord-wise corrugations on wing skin

• The utility of the black paint (lower temps., lower RCS)

• Nitrogen both in tires and in fuel tank

Aero Considerations - Aerodynamic Heating

• Fuel used also as coolant• JP-7, a high-flashing point fuel• Fuel leakage always a problem• Special hydraulic fluids (powders?) to operate at 600 F• Special tires, retracted into the fuselage fuel tank area

Fuel leakage always a problem

Air&Space Magazine, Feb/Mar 99, vol. 13 (6)

Propulsion: Turbojet or Ramjet?

• At Mach 3 cruise, turbojet engine makes only 17% of total thrust

AIAA-69-757, p. 7

Turbo-ramjet: a hybrid propulsion system

AIAA-69-757, p. 7 AIAA-69-757, p. 7

Flow must decelerate from supersonic to subsonic before the compressor first stage

http://www.airspacemag.com/asm/mag/supp/fm99/oxcart.html

Missions

• Reconnaissance (it should be RS, Pres. Johnson turned it SR)

• Interceptor (YF-12)

• Mother-ship

• Research Vehicle

Typical Reconnaissance Mission

Crickmore p 69

A modern ship, but alsoa mother-ship.

Jenkins p 50

The mother-ship delivery.

Jenkins p 44

SR-71 in High Speed Research

• NASA Dryden currently is conducting high speed flight research using two SR-71 aircraft.

• Excellent platforms to carry out research and experiments in a variety of areas (aerodynamics, propulsion,structures, thermal protection materials, high-speed and high-temperature instrumentation, atmospheric studies and sonic boom characterization)

• Data from the SR-71 high-speed research program will be used to aid designers of future supersonic/hypersonic aircraft and propulsion systems, including a high-speed civil transport.

NASA’s SR-71 and A-12

http://www.dfrc.nasa.gov/Projects/SR71/home.html

Bye-bye, Blackbird.

[Jenkins], p. 85

One airplane, several names

• A(rchangel)-12

• Blackbird

• Cygnus

• Habu

• Senior Crown

• SR-71 as Strategic Reconnaissance, but also...

• YF-12

Reference List

• Burrows, William E., “The Oxcart Cometh,” Air&Space Magazine, Vol. 13 (6), Smithsonian Institution, Washington, D. C., Feb./Mar. 1999.

• Crickmore, Paul F., “LOCKHEED SR-71 – The Secret Missions Exposed,” BAS Printers Limited, Great Britain, 1993.

• Drendel, Lou, “SR-71 Blackbird in action,” Squadron/Signal Publications, Inc., Carrolton, TX, 1982.

• “Jane’s All the World Aircraft” from years 68/69, 69/70, 74/75.

• Jenkins, Dennis R., “SR-71/YF-12 BLACKBIRDS”, WARBIRDTECH series, vol. 10, Specialty Press Publishers and Wholesalers, 1997.

• Johnson, Clarence L., “Some Development Aspects of the YF-12A Interceptor Aircraft,” AIAA Paper No. 69-757, 1969.

• Whitford, Ray, “Design for Air Combat”.