SR-71 IMPRESSIVE IN HIGH-SPEED REGIME

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP90B00170R000200280008-5
• Release Decision: RIFPUB
• Original Classification: U
• Document Page Count: 9
• Document Creation Date: December 21, 2016
• Document Release Date: May 29, 2008
• Sequence Number: 8
• Content Type: OPEN SOURCE

Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5 .
a3d
O'C-2" Id IV
By Robert R. Ropelaws ki
l eale AIDS, Calif -Continued improvements to aircraft
sv:stems as well as reconnaissance and electronic warfare
subsystervis in the U. S. Air Force/Lockheed SR-71 are
keeping that aircraft a viable and survivable strategic
reconnaissance platform after more than 16 years in
service.
The SR-71 remains unmatched in its sustained speed
and altitude performance despite its aging subsystems and
the heavy workload imposed on the crews who operate the
Mach 3-plus aircraft.. Efforts are under way to update the
SR-71's flight controls and displays with newer technolo-
gy that will improve reliability and reduce crew work-
load.
The impressive performance and demanding workload
of the SR-71 were experienced first-hand by this AVLA-
flON WEEK A SPACE TECHNOLOGY pilot in a recent flight
in the aircraft with the Ist Strategic Reconnaissance
Sqdn. of the 9th Strategic Reconnaissance Wing here at
Beale AFB. The light was preceded by two days of
briefings and preparation. including a full day in both the
front and rear cockpits of an SR-71 simulator.
it was barely enough preparation. The unique high
speed, high altitude, high temperature environment in
which the SR-71 operates makes for preflight. in-Plight
and post-flight procedures that are more lengthy and
complex than any other aircraft in the Free World inven-
tory. Special life-sustaining support systems are essential
before, during and after every flight, and normal and
Approved For Release 2008/05/29: CIA-RDP90B00l70R000200280008-5
 Approved For Release
,aviation Wea K,
Pilot Report
th
M
~Sl
gy
Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5
2008/05/29: CIA-RDP90BOO170R000200280008-5
 emergency prose Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5 'isks with standard
:SR-71 pilots and reconnaissance systems tions. - luels unoer these conditions, JP=7 fuel
operators (RSO) are thicker than any
aircraft checklist l have seen in the past.
Despite this, the SR-71 makes flight at
Mach 3 and 90,000 ft. seem easy. It was
not until 1976, in fact-more than 10
years after the SR-71 entered service-
that 9th Strategic Reconnaissance Wing
crews from Beale set world absolute and
world class speed and altitude records of
2,189 mph. and 86,000 ft. in horizontal
flight (Aw&s-r Aug. 2, 1976, p. 27). These
records still stand.
Crew preparations for the AVIATION
'WEEK demonstration flight be-
gan more than three hours
before the flight with a high-
protein breakfast of steak and
eggs in the Physiological Sup-
port Div. dining room, which is
maintained specifically to meet
the special requirements of the
SR-71 and U-2 missions.
Mission Simulation
The day before the flight,
typical missions were flown
from both the front and rear
cockpits in the SR-71 simula-
tor, under the supervision of
Maj. S. C. Thomas and Maj.
William Keller--instructor pi-
lot and instructor RSO, respec-
tively, in the simulator and the
SR-71.
There are no flight controls
per se in the rear cockpit of the
standard SR-71A, although the
RSO can control the horizontal
flight path of the aircraft
through the astro-inertial navi-
gation- system.
Neither the layout nor in-
strumentation in either cockpit
is particularly exotic. A possi-
ble exception is the navigation
system controls in the rear and
the instrumentation in the front
cockpit for monitoring and con-
trolling the aircraft's center of
gravity and the engine inlet and
exhaust systems that provide
much of the aircraft's cruise
thrust.
B. C. Thomas, who had pro-
We were then transported by van to the
aircraft, with hoses available in the van for
cooling the inside of the suit. For the
transition from the van to the aircraft,
portable cooling units were. carried.
Each SR-71 is kept in its own individual
shelter at Beale, and all preflight checks
and engine startup are accomplished in the
shelter.
The shelter floor beneath the aircraft
was covered with fuel, and it flowed at
some points to other areas of the hangar.
The SR-71 has six fuel tanks in its fuse-
with a high flash point is used in the
SR-71.
There is no evaporation with JP-7,
a lighted match can be dropped in i;
without igniting it.
Strapping into the cockpit of the SR-'
with a full pressure suit is a cumbers Nrrc
process, and Physiological Support Div.
personnel routinely accompany crewatem.
bers to assist in this. Once in, we sealed
our helmets and began breathing 100':,:
oxygen.
Standard practice in the SR-71 is to
breathe pure oxygen for at
least 30. min. prior to takeoff to
eliminate nitrogen in the body,
thus reducing the possibility of
decompression sickness at alti-
tude. SR-71 crews normally try
to be in the aircraft 50-55 min.
before their scheduled takeoff'
time, with the engines started
about 40 min. prior to takeoff.
SR-71 Instructor pilot Maj. B. C. Thomas, left, and AV,AT!ON Weinc &
Sere TECHNOLOGY Los Angeles bureau chief Robert R. Ropelewski
discuss characteristics of the SR-71 after the evaluation flight.
vided front cockpit simulator instruction,
was the pilot for the demonstration flight,
while I occupied the RSO position in_ the
rear cockpit.
About 1.5 hr. before takeoff, we went
through a brief physical examination,
including tenlperature and blood pressure
checks (standard procedure before each
SR-71 inission), then began suiting up in
full-pressure suits.
Two men are nc:e+1ed to assist the crew-
members in donnine this suit, and this
service was provided by personnel from
the '9th SRW's Physiological Support Div.
Ti'e process took about 30 min., including
a final check of the pressurization, breath-
lage and wings, but there are no internal
fuel bladders as such and the skin of the
aircraft serves as the outer wall of the
tanks.
Because of airframe expansion and con-
traction associated with heating of the
SR-71's skin at high Mach flight and
subsequent ground cooling, it is impossible
to keep the fuel tanks scaled (Aw&ST June
16. 19 0. p. to(, ). As a result, the 'tanks
leak profusely on the ground, leaving a
large pool of fuel beneath and around the
aircraft. "it's enough to give a safety
officer a heart attack the first time he sees
this," Thomas said as we walked around
the aircraft.
Cockpit Entered
Our installation in the cock-
pit was one of the final steps in
a process that had begun hours
before for the various. support
personnel associated with the
aircraft. For a typical opera-
tional mission, the process be-
gins at least a day ahead. An
18-24-hr. It-ad time is nonnally
needed to identify, prepare and
install the reconnaissance sen-
sors that will be used on a
particular mission.
In addition, a mission tape is
cut to be installed the day
before the mission in the air-
craft's astro-inertial navigation
system. The tape provides navi-
gation commands to the SR-
71's autopilot during the flight
and automatically starts and
stops sensors and their record-
ers when the aircraft approach-
es and passes the ground posi-
tions designated for reconnais-
sance.
With sensors installed and
the navigation system pro-
gramed, mission payload spe-
cialists then begin a checkout of the sys
tem about 2.5 hr. before flight. Shortly
after this, Physiological Support Div. per-
-sonnet begin their own checkout of envi-
ronmental control and life support sys-
teins.
Because of the environmental extremes
in which the SR-71 operates, a. very thick.
specially developed oil is used in the air-
craft's Pratt & Whitney J58 engines.
When temperatures drop below 30C
(86F), the oilis almost a solid and must be
preheated to 30C before the engines can
be started. Normally, this takes about I
hr- for each 10 deg. The oil must be heated.
Special ground carts are required for this
Approved For Release 2008/05/29: CIA-RDP90BOOl70R000200280008-5
 ;sto
at
t
?ad y,
ity. of
.?; try
min.
:'NIT
:: ted
? ,: c:ock-
:csn
hours
., r...
y.. ~r' ''` ka."',~?G:'s~.vzat;;.,mw,.~..h:S'!a-~ aaaG.'%astst.:y;?s3-..~ r.,r_..~aa :.:.~ ia..-+-id~'.-..~..>'.nt.. Ttl-sl..wzym-?~" iaxas
;? ii thc
;,wera- Air Force/Lockheed SR-718 dual control trainer version of the SR-71 strategic reconnaissance aircraft refuels from a Boeing KC-135 tanker
be during a training mission over the northwestern U. S. SR-718 is seen below through KC-135 boom operator's viewport as it takes on fuel
? ? ; . An from the tanker through the refueling.boorn plugged into the SR-71 behind the rear cockpit.
;;Vre and
I,Oft tape is
the air-
igation
L?,.iiUS navi-
thc SR.
I' .1
flight
Carts and
.ir record-
. pprcacb-
anc
~J%id sY
the Sys
OF Coy;
?:?v~rt S'!S
i::(Cre,ne,
en,ine
.. ?s".Y ?. 3i~ i
`tltit b
:a bout
be hL:ate-%
:?d for th...
18. 19Aviatio6 Week & Si Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5
 task, and these w, Approved For Release 2008/05/29: CIA-RDP90BOO170R0002002280008-5
climbed into the aircraft because the tem- - tracking at least three stars in its preps movable inlet guide vanes on the J58s had
perature was about I SC (6GF). ' gramed catalog of 52 stars.
' Prestart checks in both cockpits took 15 A chronometer in. the navigation system
min. Because of the high flash point of is programed with the day of the year and
JP-7 fuel, normal igniters are incapable of
igniting it.
Instead, a small amount of . triethyl
borane (TEB) is injected into. the engine
combustion chambers using an air turbine
starter plugged into the bottom of each
engine nacelle once engine rpm. has built
up. The triethyl borane ignites on contact
with the JP-7 and causes the fuel to ignite
as well. .
The TEB also? is used for each after-
burner ignition and 'for, engine air starts
(Aw&sT May 10, 1976, p. 93)..
Once the first enginewas started, it was
necessary to wait 2 min:. to insure that the
engine's hydraulics were operating proper-.:
ly before any hydraulically 'actuated sys-
tems or flight controls- could be operated.
Controls were then checked and' the sec-
ond engine was started. Additional check---
list items took another -15 min. before. we
were ready to taxi.
shifted from the axial (full open) position
to the cambered position (partially closed,.
to.turn incoming airstream at the com-
the time of. the day,,accurate to 5 millisec., pressor face). He then released the brakes
and thus knows which stars to look for and pushed the throttles into the after-,
from any location and at any given time. burner range. The left burner ignited
A star tracker mounted on gimbals takes about one-half sec. ahead of the right one,
periodic sightings that are then fed into a resulting in a snap to the right, noticeable
digital computer to correct the aircraft's .. in the cockpit. An ignition lag of up to 5
position as determined by. the system's see. is acceptable between the two after-
inertial reference unit. : burners.
The navigation system, mounted in a . Aircraft weight at that point was in
space in the upper fuselage just behind the excess of 100,000 lb., including about
RSO's cockpit, thus provides the recon- 50,000 lb. of fuel. With the two J58
naissance aircraft with precise navigation . engines producing a combined total of -
without relying on any external radio about 68,00() lb. thrust, the aircraft accel-
emission.
Had clouds prevented the star crated quickly., At 180 kt., Thomas raised
tracker from getting an accurate fix while. the none of the aircraft to a deck angle of
weIwere still on the ground, the inertial about 15 den., and the SR-7.1 lifted off at
system would have continued to provide about 210 kt. after a takeoff roll that took
-navigation guidance until we were above about 20 sec. and covered approximately,
the clouds and star tracking was possible. 4,300 ft.
Remainin
items oa th
t
ke
ck
ff
h
g
e
a
o
c
e
'Landing Gear Limitation
list- were completed in the run-up area .
.
beside?.
the -runway. Thomas held the The SR-71 has a 300-kt. landing gear
awakes and ran the throttles u
to
ilitar
extension limitation and the
irer?ft
p
m
y
a
,.utrane .ata~tutn.uon - power (maximum power without after--..reaches that speed quickly after liftoff.
As the aircraft rolled out, Thomas burner) on one engine at a time for an The landing gear retraction cycle,. on the
applied the brakes only. to :find _-that. .the...-engine trim check. Unlike most other tur- : other band, seems to be rather slow, some-
pedals went to the floor with no brake... ',.can bine_ engines, the Pratt & Whitney J58 times necessitating a power reduction to
response.,A quick recycling-of the hydrau- -be. trimmed from the cockpit of the keep the airspeed below 300 kt. until all
lie system selector switch in the front aircraft-either automatically or manual- gear units are retracted fully.
.
cockpit brought pressure.. however, and we ly: I had experienced this in the. simulator
continued taxiing toward the runway. With the trim switches in the automatic the previous day. Thomas faced the same.
Our flight plan called-for an unrefueled_'..:p~ ition during the run-up,. Thonias moni problem on takeoff in the aircraft, and .he
mission that took us. from- central Califor tored the--exhaust' gas temperature/rpm. was just about to reduce power as the
,nia over Nevada ..and,.Idaho,: then back relationship on each engine to insure that , airspeed nudged 300 kt., when the landing
across Idaho and over Oregon -before,it conformed with the figures on his check- gear finally gave a full-up indication.
returning to Beale. list. EGT was monitored throughout the ; Although an aerial refueling was not
Although it was partly cloudy as we. '.1fligbt. to' make sure there was no signifi- included in our flight, we leveled off at . .
taxied to the runway. I selected the astro- -cant variation between the two engine. 25,000 ft. as if we were going to. re uel
navigation. function on the astro-inerttal Once this and the remaining checklist from a tanker. At 400 kt. equivalent air-
navigation system' in the rear -cockpit. items.?were completed, we taxied onto the speed (KEAS) the climb to 25,000 ft. was
Within a few seconds, a white star illumi- ".departure runway. Thomas advanced the accomplished quickly, with the aircraft
noted on the mode selector button, indicat throttles to military power but . held the climbing at a rate of approximately 10,000
SR-71 touches down at Beale Afti for a touch-and-go landing during the AViATt^N WFec a SPACE TecHtioLoov demonstration flight. At typieai
landing weights such as the aircraft was-at in this photo, landing speed?is generally around 150-155 kt_
Aviation Week,& Space Technology. May t8, 1981
Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5
 Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5
fpm. We leveled off at that altitude, hold-
ing 400 kt.
While we waited for clearance to 'a
higher altitude, Thomas pulsed the con-
trols with the stability augmentation sys-
tem (SAS) on and off. Pitch, roll and yaw
oscillations were dampened almost imme-
diately with the SAS on. and the aircraft
showed no unfavorable tendency to
diverge from its normal attitude. With the
SAS off, the pulse-induced oscillations
continued for at least five to six cycles
before slowly damping out.
Simulated Failure
In the simulator, I had experienced an
SAS failure while cruising on instruments
at. Mach 3 and 80,000 ft. Chasing the nose
of the aircraft with -the stick under these
circumstances resulted in a pilot-induced .
oscillation that ultimately led to 90-deg.
nose pitch-up and loss of control of the
aircraft.
Because of the reduced pitch stability
margin at high speeds, a pitch boundary
indicator in the form of an index on the
left side of the indicator is incorporated in
the front cockpit. The same index is used
on many other aircraft to present raw
instrument landing system ((LS) glide-
slope data. The pitch boundary indicator is
controlled by both angle of attack and
pitch rate inputs. In the event of stability
augmentation system malfunction, the
pitch boundary indicator and the pitch
steering bar on the flight director attitude
indicator become the primary pitch refer-
ences. A stickshaker and stickpusher are
also associated with the pitch control sys-
tem.
In the roll and yaw axes, surface limiter
switches are incorporated to prevent
excessive control travel.
Roll limits are applied at the stick itself,
while yaw controls are imposed at the
rudder servos. The surface limiters are_
manually engaged through switches in the
cockpit that are turned on at 0.5 Mach
during acceleration.
Stability System
Because of the pitch and yaw-instabili-
ties, the SR.-71 is equipped with an elabo-
rate three-axis, eight-channel stability
augmentation system that automatically
compensates for many of the -aircraft's
natural instabilities.
At the same time, however, the SR-71 is
limited to a conservative bank angle even
with the SAS engaged.- This call- be
increased slightly with the autopilot
engaged. Until they have logged 60 hr. in
the aircraft, SR-71 pilots are rest feted to
shallow bank angles.
After several minutes at 25,000 ft., we
were cleared to continue our climb and
accelerate to Mach 3. Thomas advanced
the throttles into the afterburner range,
and there was a sudden slight yaw io the
right as the afterburners ignited asymntct-
rically again. Pulling the nose up about 10
deg., Thomas kept our speed at 0.9 -Mach
SR-71 banks hard right at low altitude over Beale AFB runway at the end of a tow-altitude,
gear-up pass down the runway. Despite its size and weight, the SR-71 showed a surprising
agility at low speed and low altitude in the landing pattern at Beale, even during single engine
approaches and go-arounds.
until we passed 30,000 ft., then adjusted
the aircraft attitude for a slow accelera-
tion to 0.95 Mach at 33,000 ft. Our rate of
climb at that point was over 6,000 fpm.
Because the highest drag, and therefore
the greatest fuel consumption, is in the
transonic regime, SR-71 crews try to get
through it as quickly as possible by per-
forming a "dipsy" maneuver. Just before
reaching 33,000 ft., Thomas pushed the
nose down slightly to pass through Mach l
and accelerate to 450 kt. at a steady
descent rate of 2,500 fpm. He then pulled
the nose up to continue the climb at 450
kt. as the Mach number slowly increased.
There was no sensation or unusual air-
craft reaction as it passed through Mach
From this point on, Thomas was busy
monitoring the various fuel, engine and
engine inlet systems used on the aircraft to
control its center of gravity, keep the
engines running at maximum efficiency
and increase the thrust of the propulsion
system.
The fuel system had pumped fuel aft
-automatically during the acceleration to
supersonic speed to shift the center of
gravity rearward in order to balance the
shift in aerodynamic forces. Because the
aircraft cannot be flown to its maximum
cruise speed without complete control of
the center of gravity, two manual backup
systems are incorporated to accomplish
this function in case the automatic con-
trols do not work. Thomas said, "More
often than not, we have to play with it."
The SR-71 uses mixed compression,
axially symmetric inlets and a free-float-
ing exhaust nozzle system to control air-
flow in and out of the engines. The func-
tioning of these systems is such that a
turbo-rariiet phenomenon occurs in which
the inlets and exhaust nozzles produce
most of the thrust at cruise speeds.
At Mach 1.4, bypass doors around the
forward, portion of the engine nacelles
began automatically to modulate the flow
of air to the engine compressors. Forward
and aft bypass doors are located in front of
the compressors, with the forward doors
spilling inlet air overboard when necessary
and the aft bypass doors venting excess
inlet air around the engine and into the
exhaust nozzle, where it produces more
thrust.
At Mach 1.7, Thomas selected the "A"
position for the aft bypass doors, opening
them slightly. Also at Mach 1.7, the
"spikes" or cones protruding from the
center of the nacelles begin retracting into
the nacelles to control the shock wave that
forms in front of the engine compressors
when the aircraft is at supersonic speeds.
The spikes move aft when the aircraft
reaches its maximum cruise speed.
Shock Wave
Between them, the spikes and the for-
ward and aft bypass doors keep the shock
wave trapped inside the nacelle and ahead
of the compressor, allowing air to enter the
compressor at subsonic speeds.
At Mach 2-2.1, the variable position
inlet guide vanes on the engines translate
from the axial to the cambered position to
maintain a constant inlet pressure on the
compressor face. The pilot must engage a
lockout switch at that point to prevent the
inlet guide vanes from returning to the
axial position. Without the IGV shift.
speed is limited to about Mach 2.
At Mach 2.6 and 450 KEAS, the auto-
pilot, if engaged, begins to follow an air-
speed bleed schedule that reduces equiva-
lent airspeed by I kt. for each incremental
increase of 0.01 ?Mach.
By Mach 2.7, the aft bypass doors in the
inlets were nearly fully closed again to
meet the ram air requirements of the
engines at that speed.
All of these steps have to be either
Aviatlon week & sa Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5
 Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5
monitored or accomplished manually by SF r ~ t
pilot is extremely busy during the acceler
ation to cruise speed and the climb to
altitude. As we pass 70,000 ft. at Mach
2.99, the SR-71's climb rate was still
above 1,000 fpm.
When the inlet and exhaust systems are
working properly, they produce up to 90%
of the SR-71's. thrust at cruise speeds,
according to Ben Rich, Lockheed-Califor-
nia Co.'s vice president of advanced devel-
opinent projects (Skunk Works). Rich was
one of the designers of -the SR-71 and its.
complex propulsion.. system.
-High Altitude Performance-
"At high altitude, the engine becomes a
supercharged. ramjet," Rich said. "At
cruise speeds, 60% of the thrust comes
from the inlets, wbicb act as superchargers
in front of the .engines. The engine is
simply an air inducer at that point."
In the exhaust nozzle, Rich said, air
comes out of the turbojets at essentially-:
the same speed it went in. "We designed
.the ejectors with_.converge nt/divergent-
same effect as the loss of an engine on-am- , however, no indication on the propulsion into the fuel cells from Dewars carried
aircraft with wing-mounted engines. An system instruments of a malfunction, and inside the aircraft.
. of speed is general-
inlet "upstart," where the shock -wave- the buzzing subsided after 1-2 min. Rich While the sensation
becomes unstable and is expelled from an : -suggested that the buzzing was caused by ly lacking in most high-flying jet aircraft,
inlet, is at least as dramatic as an engine the boundary layer separating and rent- the cruise speed of the SR-7l is such that
loss on any twin-engine aircraft, taching in one.of the inlets, which some- its rapid movement was apparent even
times hormone between Mach 2.2 and from 80,000 ft. when judged by the -broken
to cruise Mach as possible. -The aircraft.-Air Force technicians from the Stn Strategic Reconnaissance Wing's Physiological Support
gets 30% of its cruise thrust from the Div. assist Ropeiewski in connecting his pressure suit inside the rear cockpit. -
ejectors. That means the engines are pro-
ducing only 10% of cruise thrust." .tbe airframe. Thomas said it suggested the the cockpit, and a nitrogen inerting system
Because of this, a malfunction or failure- onset of an inlet upstart, and he suggested is used to reduce the possibility of fire in
in the inlet or exhaust systems .has the bracing for such an event. There was, the tanks. The nitrogen is injected directly
Mtation waste a sc Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5
crag mcrse 2.5. cloud layer 50,000-60,000 ft. below us.
When one of the inlets malfunctions and Shortly after this, we leveled off just Groundspeed at that point was above 30
the thrust it produces is- lost, there is .an above 80,000 ft. and at a speed slightly in mi./min. Thomas had engaged the autopi-
immediate sharp increase- in drag --that excess of Mach 3, with an airspeed of lot when we began our climb out of 25,000
causes the aircraft to yaw-briskly in .the- -around 330 KEAS. Thomas brought the ft., and that, coupled with the astro-
direction of the malfunctioning inlet. 1-had . throttles back to the minimum. afterburner navigation system, held us closely to our
experienced an upstart in the SR47-1-simu range, where they remained for the cruise preplanned course.
lator, but there.. .the sudden yaw was-- portion of our flight. Accuracy Checks
restrained to a-mild "kick" by-the-sir.nula The center of gravity at this point was
tor. In the aircraft. however, the reaction. at 25% mean aerodynamic chord, com- Within its capabilities, the system
can be severe enough to.dash the crews pared with 1910 at subsonic speed. The cg. checks its own accuracy and displays the
helmets against the canopy with consider- shift was accomplished automatically dur- deviation from course in one of the win-
able force. . . ing the climb and acceleration phase. down of the ANS control head in the rear
Although the SAS and autopilot -take At our cruise altitude, the curvature of cockpit. The deviation is presented in
care of the immediate need to-apply-cor. the Earth was readily apparent. and the tenths of a mile. right or left of course.
restive control inputs, an upstart is still a sky above was a very dark blue. Despite Except when the aircraft was being hand
two-page emergency-check list .event in the the thin air, there was-enough friction on flown, the course. error window generally
pilot's handbook because of the -_ large the aircraft to generate a substantial showed all zeros. In the front cockpit,
number of subsystems that can cause an amount of heat. course deviations are indicated by deflec-
unstart. Surface temperatures range from 4&0 to tions of the course deviation bar on the
Recovery must be made fairly quickly 1,200f at various spots on the aircraft's attitude director indicator. Full deflection
to avoid having to descend from altitude exterior during prolonged flight at Mach of the bar either right or left indicates the
and abort the mission. Provisions- are 3. Around the cockpit itself, the tempera- aircraft is I mi. off course.
included in the propulsion control system tune reaches about 530F. This heat could "We start to get nervous when were
for a sympathetic upstart- and restart of be felt through the narrow windows of the just a little off course," Thomas said. "The
the other engine to restore symmetry to rear cockpit, even while wearing the rela- ANS generally flies the black line," he
the aircraft's flight controls. tively thick pressure suit gloves. Tempera- added, referring to the system's ability to
During our acceleration and climb, a tures on the wing and fuselage skin that navigate accurately a course drawn with a
low rumble or buzzing developed around forms the outer wall of the aircraft's fuel black line on a map.
Mach 2.2 that could be heard and felt in 'tanks get even hotter than.they do around Thomas and other SR-71 crewmembers
 .'S Approved For For 2008/05/29: CIA-RDP90B00170R000200280008-5
said it is possible to get lost quickly at tube of apple sauce and a tube of pureed
Mach 3. and so careful attention is paid to peaches had been stowed in the rear cock-
h
A
i
l
wi
h
fli
h
'
cap
t.
spec
a
t
a
e
g
s position throughout each pit before t
the aircraft
flight. relatively thick plastic straw comes with
Fuel requirements are a major factor in each tube, and the water bottle also has an
mission planning and are based on the integral plastic straw in the cap.
assumption that the aircraft will follow the These straws are inserted through a
designated course. There is little margin small hole at the base of the pressure suit
for error. Thus, even when getting lost is helmet, then pushed into the mouth. The
not a consideration, any deviations from water bottle or the tubes are then squeezed
the planned course can add significantly to to take nourishment. The technique
fuel consumption and jeopardize the sue- worked well enough, although the system
ccssful completion of the mission. does not make provisions for inserting a
Flight Plan napkin to wipe the peach residue off the
crewmember's chin and off the inside of
Not and RSO in the SR-71 both carry
.a detailed flight plan for each mission that
lists normal flight planning information
such as en route times and estimated
arrival times over en route navigation fixes
as well. as specific bank angles to be used
and the schedule for the operation of the
various reconnaissance systems on the air-
craft. The RSO monitors all of these and
checks them against the estimated en
1 route and arrival times, waypoint informa-
tion, groundspeed and course deviation
indication.-, provided by the astro-inertial
navigation system. All times on the plan
are listed in. minutes and seconds.
-Other factors besides course deviation
can affect fuel consumption, and the
crew's .monitoring function is continuous.
The inlet spike for each engine, for exam-
pie, is controlled automatically by an air
.data computer according to the aircraft's
speed. If the spikes are as little as one-half
in:. out of-position for a given speed, fuel
-fow:could increase significantly enough to
necessitate aborting the mission. Spike
position indicators in the front cockpit are
monitored by the pilot 'throughout -the
-might, and the spikes can be positioned
.manually by the pilot if the automatic
-system malfunctions. _
Likewise, center of gravity control is
also-critical to fuel efficiency in the
SR-71. Rather than using the elevons to
trim the delta-wing aircraft, fuel is
pumped forward or aft to shift the center
-of-gravity, allowing the elevons to be kept
in a minimum drag position. A 1% error in
center of gravity location from the opti-
his mask. The hole at the base of the
helmet was self-sealing once the straws
were removed.
Shortly after the aircraft completed the-
turn and was heading back toward the
west, Thomas retarded the throttles to
military power from the minimum after-
burner position and we began a descent
Engine and inlet limitations at high speed
and high altitude are such that the SR-71
has a very narrow descent "throat"
through which it must be flown when
leaving cruise altitude. The engines are
kept at military power-maximum power
without afterburners-and airspeed is
kept at 350 kt. minimum to avoid inlet.
disturbances.
"The throttle schedule is locked in once
we start our descent," Thomas said.
"Mach 1.3 is the first point in our descent
and deceleration where we can do any-
thing to adjust the descent profile."
Descent Rate
The descent/deceleration profile began
moderately with a descent rate of about-
400 fpm. and a slight deceleration-rate.
Our speed was still at Mach 2.5 at 70000
ft. and Mach 2 at 60,000 ft. Because the
,precise altitude, capabilities of the SR-7I.
are still held secret, common procedure for
Air Force crews is to turn off the Mode C
altitude reporting function of the aircraft's
transponder above 60,000 ft. I had done,
this on our climb to altitude, and converse
ly, turned it back on again as we.
descended below that attitude on our
- return. The rate of descent had reached
-mum can result in a mission abort for low 3,500 fpm. by 60.000 ft. and was at 5,000
fuel, Thomas said. fpm. when we passed through 50,000 ft. at
"It's really incumbent on the pilot to about Mach 1.6. --
As wd passed to the south of Boise, pitched up slightly from a 15-deg. nose
I Idaho, the aircraft banked to the left in a down attitude to about 5 deg, nose down. -
programed I80-deg. turn that took us to Our equivalent airspeed at that point was
the.east and then to the north of the city still about 365 kt.
before the turn was completed. At Mach - Throughout the descent, Thomas had
3,-the SR-7i does not turn very quickly, been monitoring center of gravity, inlet
and at a bank angle of 30 deg., our spike and bypass door movements, and
140-deg. turn described a semicircle engine behavior in approximately the
around Boise with a diameter of about 170 reverse order from our earlier climb and
mi. acceleration. Once we had slowed to sub-
The turn took lone enough to allow me sonic speed, the workload decreased and it
to sample the specially packaged foods was possible to fly the SR-71 more like a
carried by SR-71 crews on extended mis- conventional aircraft.
Circle Number 54 on Reader Service, Card.
si.ons..A soft plastic bottle with water, a With the autopilot still engaged, it
Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5
 F-15B Tested With Allis Pod
USAF/McDonnell Douglas F-15B Eagle fighter -equipped with a
Martin Marietta Automatic Tracking Laser Illumination System (Atlas
2) pod (arrow) is shown during a series of airworthiness flights at St.
Louis before going to Edwards AFB, Calif.. to begin a 15-month
flight test program of 150 flights. During development testing of the
selected waypoint No. 10 in the ANS--
the coordinates for Beale AFB-and
pushed the "direct steer" button on -the
ANS control head.
The aircraft turned from its westerly
heading to a more southerly one, heading
directly toward Beale, which was still-
about 80 mi. away. Had Thomas been
flying manually, he could have followed
the ANS-gencrated flight director steerirg-
commands on his attitude director indica-
tor to establish the proper heading for the
return to Beale.
While passing through a layer of brokcn-
clouds between 15,000 and 10,000 ft. dur-
ing our descent, some light turbulence was
encountered that demonstrated the. struc-
tural flexibility of the SR-71.
The center of gravity of the aircraft-is
located in the same general location as-
that of the landing gear, roughly at-the-
midpoint of the aircraft`s 107.4-ft. overall
length. The cockpit is approximately 50 ft.
in front of this.
Light Turbulence
In light turbulence, the effect in the _
cockpit was like sitting at the end of a.
diving Lvaard, bouncing up and down sever-
al times during each patch of turbulence.
It a--as net - particularly uncomfortable.
S11-71 crews have seen significantly-more
pronounced oscillations in more severe tur-
htjcuee, according to Thomas.
pattern at Scale.
Onc1 in the landing
ahc SR-7i behaved like a conventional
aircraft. and even Showed a surprising ease
of handling that bellied its size.
Thomas flew a tight pattern to an initial
kow pass, an approach and go-around with
a simulated engine failure, a touch-and-go
landing and a final landing. Airspeed was
Integrated Flight Fire Control (IFFC)/Firefly 3 program, the F-1513
was scheduled to make 10 airworthiness flights at St. Louis. During
testing, air-to-air weaponry will be fired at simulated targets while
the F-15B maneuvers at high offset angles. Large shape beneath
aircraft is a centerline-mounted external fuel tank.
kept around 250 kt. in the pattern, slowing
to 180 kt. on final.
For the engine-out demonstration,
Thomas. brought. the right engine to idle.
There was little yaw associated with the
loss of thrust on the right wing because the
stability augmentation system automati-
cally applied corrective rudder inputs. The
left wing was also lowered about 10 deg. to
minimize drag.
The aircraft was much tighter now, and
less than military power was needed on the
left engine to maintain speed and altitude
in the pattern.
For the go-around in this condition, the
left afterburner was selected at about 300
ft., necessitating a steeper left bank of
about 20 deg. to maintain our track down
the runway.
The SAS again took care of corrective
rudder inputs, and Thomas kept his feet
on-the cockpit floor during the climbout
and downwind turn.
A-conventional touch-and-go and then a
final landing followed. Although the long
fuselage and large rudders of the SR-71
can pose some difficulties in high cross-
winds, crewmcntbers said the aircraft is
=not .generally a difficult one to land. Our
own landings appeared to be fairly rou-
tine.
A nose-up attitude of about 8 deg. was
held on the downwind leg, increasing to 9
deg. on base, 10 deg. on Sinai and about 12
deg. for touchdown. Forward and periph-
eral visibility remains good throughout the
approach.
The delta wing of the SR-71 generates a
considerable amount of ground effect as it
nears the runway. helping to soften the
landing. Both our touch-and-go and full-
stop landing were exceptionally smooth.
Once we were on the ground, Thomas
deployed the drag chute that is. towed in
the upper rear fuselage between the
canted rudders. This provides an approxi-
mate 0.5 g deceleration force, and brought
us forward slightly in our seats. The chute
must be released from the aircraft before
slowing below 60 kt. in order to avoid
getting it tangled in the rudders. This was
done, and we slowed to taxi speed with a
considerable amount of runway remain-
ing.
Our total Right time was 1.4 hr., during:
which we covered about 1,800 mi. as ''ell
as four circuits of the landing-pattern.
From the pilot's point of view, there is a
glaring paradox in the SR-71 in terms of
the late 1950s/early 1960s technology
used in the cockpit to manage a system
whose performance is still considered
advanced in the early 1980s
.
Improvement Programs
Recognizing this, the Air Force has
several improvement programs under way
to modernize flight controls and systems in
the aircraft, with the aim of improving
reliability and thereby reducing, cockpit
workload for SR-71 crewrnembers.
One of the main improvements will be a .
digital automatic flight and inlet control
system that is being flight tested and is
expected to appear on operational SR-7 Is
in August.
The new system will integrate the func-
tions of several separate older units,
including the present older-generation
central air data computer, analog air inlet
computers that control the spikes and for-
ward bypass doors, the present autopilot,
stability augmentation system and auto-
matic pitch warning system. Q
Aviation Week & Space Technology. May 1t3, t9a1
Approved For Release 2008/05/29: CIA-RDP90B00170R000200280008-5 w___