Friday, March 02, 2012

Flying the U-2



Subject: Flying the U-2

U-2 Dragon Lady
This is quite interesting for pilot types.

Unfortunately this is long, but it is remarkable what the U-2 can do.


High Flight, by Barry Schiff

Maj. Dean Neeley is in the forward, lower cockpit of the Lockheed U-2ST,
a two-place version of the U-2S, a high-altitude reconnaissance aircraft
that the Air Force calls "Dragon Lady.." His voice on the intercom
breaks the silence. "Do you know that you're   the highest person in the
world?" He explains that I am in the higher of the two cockpits and that
there are no other U-2s airborne right now. "Astronauts don't count," he
says, "They're out of this world."

We are above 70,000 feet and still climbing slowly as the aircraft
becomes lighter. The throttle has been at its mechanical limit since
takeoff, and the single General Electric F118-GE-101 turbofan engine
sips fuel so slowly at this altitude that consumption is less than when
idling on the ground.  Although true airspeed is that of a typical
jetliner, indicated airspeed registers only in double digits.

I cannot detect the curvature of the Earth, although some U-2 pilots
claim that they can. The sky at the horizon is hazy white but
transitions to midnight blue at our zenith. It seems that if we were
much higher, the sky would become black enough to see stars at noon..
The Sierra Nevada, the mountainous spine of California, has lost its
glory, a mere corrugation on the Earth. Lake Tahoe looks like a fishing
hole, and rivers have become rivulets. Far below, "high flying"
jetliners etch contrails over Reno, Nevada, but we are so high above
these aircraft that they cannot be seen.

I feel mild concern about the bailout light on the instrument panel and
pray that Neeley does not have reason to turn it on. At this altitude I
also feel a sense of insignificance and isolation; earthly concerns seem
trivial.  This flight is an epiphany, a life-altering experience.

I cannot detect air noise through the helmet of my pressure suit. I hear
only my own breathing, the hum of avionics through my headset and,
inexplicably, an occasional, shallow moan from the engine, as if it were
gasping for air. Atmospheric pressure is only an inch of mercury, less
than 4 percent of sea-level pressure. Air density and engine power are
similarly low. The stratospheric wind is predictably light, from the
southwest at 5 kt, and the outside air temperature is minus 61 degrees
Celsius.

Neeley says that he has never experienced weather that could not be
topped in a U-2, and I am reminded of the classic transmission made by
John Glenn during Earth orbit in a Mercury space capsule: "Another
thousand feet, and we'll be on top."

 Although not required, we remain in contact with Oakland Center while
in the Class E   airspace that begins at Flight Level 600. The U-2's
Mode C transponder, however, can   indicate no higher than FL600. When
other U-2s are in the area, pilots report their   altitudes, and ATC
keeps them separated by 5,000 feet and 10 miles.

 Our high-flying living quarters are pressurized to 29,500 feet, but
100-percent oxygen   supplied only to our faces lowers our physiological
altitude to about 8,000 feet. A   pressurization-system failure would
cause our suits to instantly inflate to maintain a   pressure altitude
of 35,000 feet, and the flow of pure oxygen would provide a
physiological altitude of 10,000 feet.

 The forward and aft cockpits are configured almost identically. A
significant difference   is the down-looking periscope/driftmeter in the
center of the forward instrument panel.   It is used to precisely track
over specific ground points during reconnaissance,   something that
otherwise would be impossible from high altitude. The forward cockpit
also is equipped with
 a small side-view mirror extending into the air stream. It is used to
 determine if the U-2 is generating a telltale contrail when over hostile
 territory.

 Considering its 103-foot wingspan and resultant roll dampening, the U-2
 maneuvers surprisingly well at altitude; the controls are light and nicely
 harmonized. Control wheels (not sticks) are used, however, perhaps because
 aileron forces are heavy at low altitude. A yaw string (like those used on
 sailplanes) above each canopy silently admonishes those who allow the
 aircraft to slip or skid when maneuvering. The U-2 is very much a
 stick-and-rudder airplane, and I discover that slipping can be avoided by
 leading turn entry and recovery with slight rudder pressure.

 When approaching its service ceiling, the U-2's maximum speed is little
 more than its minimum. This marginal difference between the onset of stall
 buffet and Mach buffet is known as coffin corner, an area warranting
 caution. A stall/spin sequence can cause control loss from which recovery
 might not be possible when so high, and an excessive Mach number can
 compromise structural integrity. Thankfully, an autopilot with Mach hold
 is provided.

 The U-2 has a fuel capacity of 2,915 gallons of thermally stable jet fuel
 distributed among four wing tanks. It is unusual to discuss turbine fuel
 in  gallons instead of pounds, but the 1950s-style fuel gauges in the U-2
 indicate in gallons. Most of the other flight instruments seem equally
 antiquated.



I train at 'The Ranch'

 Preparation for my high flight began the day before at Beale Air Force
Base  (a.k.a. The Ranch), which is north of Sacramento, California, and was
 where German prisoners of war were interned during World War II. It is
home to
 the 9th Reconnaissance Wing, which is responsible for worldwide U-2
 operations, including those aircraft based in Cyprus; Italy; Saudi
Arabia; and South
 Korea.

 After passing a physical exam (whew!), I took a short, intensive course
 in high-altitude physiology and use of the pressure suit. The 27-pound
Model
 S1034 "pilot's protective assembly" is manufactured by David Clark (the
 headset people) and is the same as the one used by astronauts during
 shuttle launch and reentry.

 After being measured for my $150,000 spacesuit, I spent an hour in the
 egress trainer. It provided no comfort to learn that pulling up mightily
 on the handle between my legs would activate the ejection seat at any
 altitude or airspeed. When the handle is pulled, the control wheels go
fully
 forward, explosives dispose of the canopy, cables attached to spurs on
your boots
 pull your feet aft, and you are rocketed into space. You could then free
 fall in your inflated pressure suit for 54,000 feet or more. I was told
 that "the parachute opens automatically at 16,500 feet, or you get a
refund."

 I later donned a harness and virtual-reality goggles to practice steering
 a parachute to landing. After lunch, a crew assisted me into a
pressure suit
 in preparation for my visit to the altitude chamber. There I became
 reacquainted with the effects of hypoxia and was subjected to a sudden
 decompression that elevated the chamber to 73,000 feet. The pressure suit
 inflated as advertised and just as suddenly I became the Michelin man.
I was
 told that it is possible to fly the U-2 while puffed up but that it is
 difficult.

 A beaker of water in the chamber boiled furiously to demonstrate what
would
 happen to my blood if I were exposed without protection to ambient
pressure
 above 63,000 feet.

 After a thorough preflight briefing the next morning, Neeley and I put on
 long johns and UCDs (urinary collection devices), were assisted into our
 pressure suits, performed a leak check (both kinds), and settled into
a pair
 of reclining lounge chairs for an hour of breathing pure oxygen. This
 displaces nitrogen in the blood to prevent decompression sickness (the
 bends) that could occur during ascent.

 During this "pre-breathing," I felt as though I were in a Ziploc bag-style
 cocoon and anticipated the possibility of claustrophobia. There was none,
 and I soon became comfortably acclimatized to my confinement.

 We were in the aircraft an hour later. Preflight checks completed and
 engine started, we taxied to Beale's 12,000-foot-long runway. The single
 main landing gear is not steerable, differential braking is
unavailable, and
 the dual tailwheels move only 6 degrees in each direction, so it takes
a lot
 of concrete to maneuver on the ground. Turn radius is 189 feet, and I
had to
 lead with full rudder in anticipation of all turns.

 We taxied into position and came to a halt so that personnel could remove
 the safety pins from the outrigger wheels (called pogos) that prevent one
 wing tip or the other from scraping the ground. Lt. Col. Greg "Spanky"
 Barber, another U-2 pilot, circled the aircraft in a mobile command
vehicle
 to give the aircraft a final exterior check.

 I knew that the U-2 is overpowered at sea level. It has to be for its
 engine, normally aspirated like every other turbine engine, to have enough
 power remaining to climb above 70,000 feet. Also, we weighed only 24,000
 pounds (maximum allowable is 41,000 pounds) and were departing into a
brisk
 headwind. Such knowledge did not prepare me for what followed.

 The throttle was fully advanced and would remain that way until the
 beginning of descent. The 17,000 pounds of thrust made it feel as though I
 had been shot from a cannon. Within two to three seconds and 400 feet of
 takeoff roll, the wings flexed, the pogos fell away, and we entered a
 nose-up attitude of almost 45 degrees at a best-angle-of-climb airspeed of
 100 kt. Initial climb rate was 9,000 fpm.

 We were still over the runway and through 10,000 feet less than 90 seconds
 from brake release. One need not worry about a flameout after takeoff in a
 U-2. There either is enough runway to land straight ahead or enough
altitude
 (only 1,000 feet is needed) to circle the airport for a dead-stick
approach
 and landing.

 The bicycle landing gear creates little drag and has no limiting airspeed,
 so there was no rush to tuck away the wheels. (The landing gear is not
 retracted at all when in the traffic pattern shooting touch and goes.)

 We passed through 30,000 feet five minutes after liftoff and climb rate
 steadily decreased until above 70,000 feet, when further climb
occurred only
 as the result of fuel burn.

 On final approach Dragon Lady is still drifting toward the upper
limits of the
 atmosphere at 100 to 200 fpm and will continue to do so until it is
time to descend.
 It spends little of its life at a given altitude. Descent begins by
retarding
 the throttle to idle and lowering the landing gear. We raise the spoilers,
 deploy the speed brakes (one on each side of the aft fuselage), and engage
 the gust alleviation system. This raises both ailerons 7.5 degrees above
 their normal neutral point and deflects the wing flaps 6.5 degrees upward.
 This helps to unload the wings and protect the airframe during possible
 turbulence in the lower atmosphere.

 Gust protection is needed because the Dragon Lady is like a China
doll; she
 cannot withstand heavy gust and maneuvering loads. Strength would have
 required a heavier structure, and the U-2's designer, Clarence "Kelly"
 Johnson, shaved as much weight as possible-which is why there are only two
 landing gear legs instead of three.. Every pound saved resulted in a
10-foot increase in ceiling.

 With everything possible hanging and extended, the U-2 shows little desire
 to go down. It will take 40 minutes to descend to traffic pattern altitude
 but we needed only half that time climbing to altitude.

 During this normal descent, the U-2 covers 37 nm for each 10,000 of
 altitude lost. When clean and at the best glide speed of 109 kt, it has a
 glide ratio of 28:1. It is difficult to imagine ever being beyond glide
 range of a suitable airport except when over large bodies of water or
 hostile territory. Because there is only one fuel quantity gauge, and it
 shows only the total remaining, it is difficult to know whether fuel is
 distributed evenly, which is important when landing a U-2. A low-altitude
 stall is performed to determine which is the heavier wing, and some
fuel is
 then transferred from it to the other.

 We are on final approach with flaps at 35 degrees (maximum is 50 degrees)
 in a slightly nose-down attitude. The U-2 is flown with a heavy hand when
 slow, while being careful not to overcontrol. Speed over the threshold is
 only 1.1 VSO (75 kt), very close to stall. More speed would result in
 excessive floating.

 I peripherally see Barber accelerating the 140-mph, stock Chevrolet
Camaro
 along the runway as he joins in tight formation with our landing
aircraft.  I
 hear him on the radio calling out our height (standard practice for
all U-2
 landings). The U-2 must be close to normal touchdown attitude at a
height of
 one foot before the control wheel is brought firmly aft to stall the wings
 and plant the tailwheels on the concrete. The feet remain active on the
 pedals, during which time it is necessary to work diligently to keep the
 wings level. A roll spoiler on each wing lends a helping hand when its
 respective aileron is raised more than 13 degrees.

 The aircraft comes to rest, a wing tip falls to the ground, and crewmen
 appear to reattach the pogos for taxiing.

 Landing a U-2 is notoriously challenging, especially for those who have
 never flown taildraggers or sailplanes. It can be like dancing with a lady
 or wrestling a dragon, depending on wind and runway conditions. Maximum
 allowable crosswind is 15 kt.

 The U-2 was first flown by Tony Levier in August 1955, at Groom Lake (Area
 51), Nevada. The aircraft was then known as Article 341, an attempt by the
 Central Intelligence Agency to disguise the secret nature of its project.
 Current U-2s are 40 percent larger and much more powerful than the one in
 which Francis Gary Powers was downed by a missile over the Soviet Union on
 May 1, 1960.

 The Soviets referred to the U-2 as the "Black Lady of Espionage"
because of
 its spy missions and mystique. The age of its design, however, belies the
 sophistication of the sensing technology carried within. During U.S.
 involvement in Kosovo, for example, U-2s gathered and forwarded data via
 satellite to Intelligence at Beale AFB for instant analysis. The results
 were sent via satellite to battle commanders, who decided whether attack
 aircraft should be sent to the target. In one case, U-2 sensors detected
 enemy aircraft parked on a dirt road and camouflaged by thick, overhanging
 trees. Only a few minutes elapsed between detection and destruction. No
 other nation has this capability.

 The U-2 long ago outlived predictions of its demise. It also survived its
 heir apparent, the Lockheed SR-71 Blackbird. The fleet of 37 aircraft is
 budgeted to operate for another 20 years, but this could be affected
by the
 evolution and effectiveness of unmanned aircraft.

 After returning to Earth (physically and emotionally), I am escorted
to the
 Heritage Room where 20 U-2 pilots join to share in the spirited
celebration
 of my high flight. Many of them are involved in general aviation and some
 have their own aircraft.

 The walls of this watering hole are replete with fascinating memorabilia
 about U-2 operations and history. Several plaques proudly list all who
have
 ever soloed Dragon Lady. This group of 670 forms an elite and unusually
 close-knit cadre of dedicated airmen.

  ------------------
 Bill Evelyn
 When in doubt ... go faster.