On Jul. 6, 1972, Mery Evenson and Coz Mallozzi flew SR-71 Blackbird test airframe ‘955 on a 3-hour sortie, checking out refuelling flight envelope and ‘dry-boom’ contact checks with the boom-equipped Boeing 747.
Taken on Jul. 6, 1972 the interesting photo in this post features Boeing 747 N1352B (also known as RA-001, N1352B which was the first Boeing 747 ever built) refuelling SR-71 Blackbird 955.
Noteworthy, N1352B was retained by Boeing and used as a test aircraft, and as a research platform for ongoing system developments with the 747 series.
As told by Paul F Crickmore in his book Lockheed Blackbird: Beyond the Secret Missions (Revised Edition), in 1970 General P. K. Carlton, commander of the 15th Air Force, became interested in extending SR-71 missions to fully encompass the concept of ‘global reach’.
He asked his Director of Reconnaissance, Lt Col Don Walbrecht, to conceive a post-SIOP coverage of the Soviet landmass by SR-71s assisted by advanced tankers that were not yet programmed into SAC’S inventory. He said, ‘Recce’, you know that Habu: well I want a plan to help sell the Air Staff on the idea of big new tankers.’ In the next few days, Don and his fellow 15th AF reconnaissance officers drew up a plan whereby the existing SIOP was covered with lots of tankers and all of the SR-71s.
After Don briefed the ‘Boss’ the first time, P. K. said, ‘Back to the drawing boards, Recce; you’re not thinking big.’ A few days later, a new plan was briefed, showing that a dozen pre-positioned KC-747s and a dozen Beale-based Habus could cover all probable targets less than five hours after the initial ICBM lay-down. ‘That’s more like it!’ he said. ‘That’ll help advocate the use of the Jumbos.’ Soon after, newly-promoted Col Walbrecht found himself assigned to SAC Headquarters, where he was ‘advocating new tankers and re-engined KC-135s’ as the division chief of advanced strategic aircraft systems.
To further the cause of an advanced tanker, General Carlton stimulated a test programme that mated Boeing’s modified number one 747 test airframe with an SR-71. On Jul. 6, 1972, Mery Evenson and Coz Mallozzi flew the Palmdale test airframe ‘955 on a 3-hour sortie, checking out refuelling flight envelope and ‘dry-boom’ contact checks with the boom-equipped 747. The same day, B-52s and various fighters also took their turn in the 747 contact tests.
Throughout the 1970s, General Carlton used the 747/SR-71 recce concept, and the success of that test flight, to help promote SAC’S Advanced Cargo Transport Aircraft (ACTA), which eventually bore fruit in the 1980s with the purchase of 60 KC-10s. For SR-71 pilots, the KC-10 made the air-refuelling task much easier, raising the base refuelling block up to 33,000ft and the speed to Mach 0.88.
Today the world’s only KC-747 tanker is flown by the Islamic Republic of Iran Air Force (IRIAF).
N1352B “City of Everett” was later re-registered as N7470, before being retired to the Boeing Museum of Flight, also the home of the only remaining M-21.
The following video is a summary of the aircraft modifications and flight tests of the proposed KC-747.
Lockheed Blackbird: Beyond the Secret Missions (Revised Edition) is published by Osprey Publishing and is available to order here.
Photo credit: U.S. Air Force