KC-135 From Eisenhower Era Flies On For PA ANG

by Aero-News Senior Correspondent Kevin R.C. "Hognose" O'Brien

In 1959, cars had tailfins, which peaked that year with the Cadillac Eldorado and various Chrysler products. Kids learned to "Duck and Cover." The New York Times admired Fidel Castro. And the US Air Force ordered a block of KC-135A-BN Stratotankers, Boeing C/Ns 17931 to 18011, USAF serials 59-1443 To 59-1523.

One of the surviving KC-135s, 17948 to its Seattle factory and 59-1460 to the Air Force, was brought to Embry-Riddle's Florida Skyfest by its current proprietors, the 171st Air Refueling Wing of the Pennsylvania Air National Guard. The plane was decorated with attractive nose art displaying an eagle and the legend "Classic Iron," which basically sums up the Pittsburgh-based crewmembers' pride in their old, but clean-enough-to-eat-off-of, jet.

The 171st is based at Pittsburgh International Airport and has 400 full-time and 1000 part-time Guardsmen. They operate 16 KC-135T jet tankers, which once fueled the high-flying SR-71 reconnaissance fleet, and now support Air Force and allied missions worldwide.

The KC-135 can transport cargo or personnel, or carry fuel for inflight refueling. It doesn't have the nose or tail doors that usually define military cargo planes, but it has a side cargo door like those on cargo conversions of airliners. It can be fitted with airline-type seat units -- with the seats facing to the rear -- or paratroop-type seats along the side of the plane. (They're only paratroop-"type" seats. The airplane is not designed for intentional parachute jumps).

In tanker mode, the plane can deliver fuel to US Air Force aircraft through a high-volume fueling boom that is "flown" into position on the receiving aircraft by a highly trained enlisted aircrew member, the boom operator, as the receiving aircraft's pilot maintains a close formation. The boom operator lies in a ventral position in the aircraft, looking through a window and flying the boom with a control stick. Naval and foreign aircraft can refuel with a probe-and-drogue system as well.

This specific plane has an interesting history. It was the 363rd KC-135 built of 820, and made its first flight on February 16th, 1960 -- the Air Force accepted it within ten days. Tankers were then, as now, vital to national security. Ike was still President, and no one serious was talking about sending men to the moon, and the Strategic Air Command maintained a standing patrol in the sky, ready to rain nuclear death on the air bases and cities of Russia, should they do the same to us.

Old 1460 spent some time as a as a KC-135A before being modified to carry special JP-7 fuel for the SR-71A reconnaissance aircraft. Normal JP-4 (which used in those days), freezes at the high stratospheric altitudes where the SR-71A operated, and so, special fuel with a much lower freezing point -- JP-7 -- was compounded. The SR-71A fuelers, including 1460, were dedicated to that mission and were designated KC-135Q. Fifty-six of them were converted in all.

Most of the changes were in navigation and communications equipment, but the KC-135Q also needed to keep its own fuel separate from fuel it planned to offload (regular planes could use JP-7, but the SR-71 couldn't use JP-4 or its replacement, JP-8, which is basically Jet A with a military additive package).

After the SR-71A was retired in the 1990s, the KC-135Q fleet -- including 1460 -- was reconverted to service conventional aircraft.

At ERAU's Florida Skyfest last weekend, on Saturday, 1460 was open to the public for tours. Many members of the public express surprise about how open the plane is. They expect it to be full of fuel tanks, but the KC-135s entire fuel load -- for itself and that it can offload to other aircraft -- is borne in the wings and under the reinforced cargo floor. Even when fully laden with fuel, the cargo bay is wide open. Weight considerations prevent fuel and cargo from being carried at once.

The original KC-135A was closely based on the original Boeing "Dash-80" demonstrator (which actually tested the prototype refueling boom), and was a forerunner of the legendary 707 airliner.

Over the years, the KC-135 fleet has seen many changes and upgrades. There have been two complete powerplant replacements, numerous cockpit overhauls, and aerodynamic fixes (the whole fleet was retrofitted with a taller fin to increase yaw stability).

For many 135s, the original J57-P-59W turbojet engines were replaced by refurbished low-bypass turbofans removed from decommissioned commercial 707s, called the Pratt & Whitney TF33-PW-102. This gave the tankers better fuel efficiency, less visual signature (smoke), and something they hadn't had before -- thrust reversers for increased safety.

A much more comprehensive program to re-engine KC-135s was undertaken in the 1990s. The TF33s or J57s were replaced with CFM56 high-bypass turbofans which yielded even larger efficiency, noise-reduction, and maintenance gains. Of course, the additional thrust provided by the successive generations of engine is a big improvement, too. This upgrade replaced the entire engine pylons and nacelles on the affected KC-135s -- and involved over twelve linear miles of new wiring per plane.

Increased fuel efficiency from the turbofan upgrades - 25% in the case of the CFM-56 swap -- has tactical, not just economical, significance. With less fuel needed to haul the tanker itself, more is available to offload to tactical aircraft, mission profile remaining equal.

Fatigue and corrosion are bitter enemies of older airplanes, and all KC-135s have had major wing work to combat fatigue. The lower wing skins, which bear much of the air loads, were replaced by parts not only of new design but of an improved alloy that was not available when the original plane was made. Each rebuild required 564 parts, 1,500 square feet of aluminum, 32,200 steel fasteners and 19,500 aluminum rivets.

1460 has seen its share of changes, receiving its new wing skins in December, 1981, and the CFM-56 powerplant upgrade on December 20th, 1994 which made the plane a KC-135T.

She also displays war honors, proudly bearing the ribbons of the Air Force Distinguished Unit Award with Oak Leaf Cluster, and Southwest Asia Service Medal with two battle stars.

Like any old lady who's aging gracefully, the KC-135 spends more time primping than her youthful equivalents; Air Force figures suggest that it takes 16 maintenance hours per flight hour. That keeps a lot of the 1400 men and women of the 171st Air Refueling Wing busy, because tankers are always in demand.

Several attempts to replace the KC-135 flight have come to naught. A new attempt even now is underway. But for the time being the 171st will be flying what they like to call Classic Iron. Boeing engineers are cautiously optimistic that the KC-135 fleet could fly on into the 2020s and beyond. Not bad, for a plane that might have been designed by their grandfathers.

Not many things survive from the 1950s, but the surviving tailfin Cadillacs are now classics.  And people still want to blow our kids up. The New York Times still admires Fidel Castro. And KC-135T 59-1460 is still going strong.

FMI: www.papitt.ang.af.mil