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
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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”)
3.5
3
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Mig-25 engines reported being
destroyed after flying at 3.2M.
Unofficial maximum speed was 2.8M
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XB-70 only dashed at 3.2M - most of
the flight was subsonic.
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The SR-71 used to fly at 3.0M+ for
hours.
2.5
2
Max
Leveled
Mach
1.5
MIG-25
XB-70
SR-71
0.5
0
Concorde
1
Thrust-to-Weight Ratio Comparison
• The Mig-25 fuselage has a
much smaller fineness ratio.
Mig-25
XB-70
SR-71
T/W
Concorde
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Jane’s, 74/75
Wing-Loading Comparison
120
100
80
60
W/S
[lbf/ft2]
40
Mig-25
XB-70
SR-71
0
Concorde
20
More on T/W x W/S Comparison
MIG-25
SR-71
XB-70
Concorde
[Whitford], p. 39
Wing Geometry Comparison
Speed increase demands thinner wings.
[Whitford], p. 30
Speed increase also demands larger turn radii.
[Jenkins], p. 93
Aerodynamic Considerations
Another application of the KISS methodology
• High fineness ratio bodies
• Highly swept double-delta wing.
[Whitford], p. 188
Aerodynamic Considerations - FUSELAGE
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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
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Double-delta plan form allows high (t/c) ratio to minimize wave drag
Swept keeps most of the wing in Mach cone :   90  sin ( 1 )
1
cone
– For Mach 3.0 flight  cone  70.5
– SR-71 wing sweep angle: LE  60
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M
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
[Whitford], p. 188
Aero Considerations - VERTICAL TAILS
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All moving tails (+20/-20 deg)
Cant angle to
– reduce induced rolling moment when dr ≠ 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.
Crickmore p 44
Drendel p 20
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)
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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
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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
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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 also
a 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
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A(rchangel)-12
Blackbird
Cygnus
Habu
Senior Crown
SR-71 as Strategic Reconnaissance, but also...
YF-12
Reference List
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Burrows, William E., “The Oxcart Cometh,” Air&Space Magazine, Vol. 13 (6), Smithsonian Institution, Washington,
D. C., Feb./Mar. 1999.
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Crickmore, Paul F., “LOCKHEED SR-71 – The Secret Missions Exposed,” BAS Printers Limited, Great Britain,
1993.
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Drendel, Lou, “SR-71 Blackbird in action,” Squadron/Signal Publications, Inc., Carrolton, TX, 1982.
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“Jane’s All the World Aircraft” from years 68/69, 69/70, 74/75.
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Jenkins, Dennis R., “SR-71/YF-12 BLACKBIRDS”, WARBIRDTECH series, vol. 10, Specialty Press Publishers and
Wholesalers, 1997.
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Johnson, Clarence L., “Some Development Aspects of the YF-12A Interceptor Aircraft,” AIAA Paper No. 69-757,
1969.
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Whitford, Ray, “Design for Air Combat”.