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North American XF-108 Rapier

1955 COLD WAR X-PLANE

History of the North American Rapier XF-108

The prospect of high-speed, high-altitude bombers intrigued war planners on both sides of the Cold War. Advances in jet technology and supersonic flight made this desire a reality, and many projects appeared during this period in the history of military aviation.

Countering this bomber threatbefore the arrival of an effective anti-missile networkwas the high-speed interceptors tasked with striking the enemy head-on. This deterrence is as old as military aviation itself - specialized interceptors bred to intercept incoming enemy threats.

In 1956, the USAF adopted the Convair F-102 "Delta Dagger" for interception missions, and in 1959 adopted the improved successor, the Convair F-106 "Delta Dart". Over 1,000 of the former and over 340 of the latter were achieved during their respective production runs. The Delta Arrow is particularly notable for its Mach 2.3 speed and 29,000 feet per minute climb rate.

Continuing the same design approach, the USAF fleshed out a new high-performance long-range interceptor program when the F-102 went online and the F-106 entered production.

The October 1955 U.S. Air Force specification called for a lean interceptor capable of speeds in excess of Mach 1.5, a service ceiling of 60,000 feet, and a range of 1,000 miles. This guy will be charged with intercepting contemporary Soviet bombers threatening North American and European airspace.

For survivability and the required speed, the fuselage will contain two engines arranged side by side. The workload of the mission will be split between the two crew members.

Like other interceptors of the era, the aircraft carried an advanced fire control system (FCS) to help deliver ordnance -- in this case, bomber kill missiles.

The specification was welcomed by eight competing companies, although only Lockheed, North America and Northrop were invited to work on further designs. Of the three, the North American design best met the requirements of the USAF, whose submission was accepted as the "XF-108" (the aircraft did not receive the "Rapier" designation until May 1959). But it all ended when the program was shut down on May 9, 1956, due to the usual suspectsbudget issues and politics.

After the battle, the program resumed in April 1957 and two prototypes were ordered from North American Airlines.

The North American product (model NA-257) began a lengthy design process that continued to evolve as needs changed and technology advanced. Hughes was tasked with developing the FCS to manage the missile, with GE providing the engine.

During this period, North America was also working on the USAF's XB-70 Valkyrie Mach 3 supersonic bomber, so the XF-108 shared the XB-70's GE engine. The same ejection pods from the XB-70 are also used on the XF-108.

The design line of the XF-108 also somewhat mimics the design of the XB-70 - delta wing plane, canard front wing, square base, etc.

Several factors began to have an adverse effect on the XF-108 program - the Soviet Union's commitment to an effective missile defense network (making high-altitude supersonic bombers obsolete) and the preferential use of intercontinental ballistic missiles (ICBMs) for the delivery of nuclear warheads (destruction) of strategic bomber methods ) reduced the USAFs interest in new, expensive interceptors. Early on, the XF-108 had a canard nose plane for pitch control, a basic delta wing plan, and no less than three vertical stabilizers (one on the fuselage and two on the trailing edge of each wing). The final form is an interpretation of the aircraft - showing the continued development of this interceptor - without the canards and two of the three vertical stabilizers (upper only), while the delta wings form a "double". A scale schematic of the Delta A Full-XF-108 was submitted to the US Air Force for review in January 1959.

The order was reduced to just 20 aircraft.

The XF-108 program is to produce only the models mentioned above, since on September 23, 1959, the USAF retired the interceptor. Some of the work in the XF-108 was rebuilt for the more successful North American A-5 Vigilant reconnaissance-attack bomber, which was adopted by the United States Navy (USN) in 1961. In the XF-108 design form (sub-retaining the hull and system), saw production totaled 156 units.

Vigilante aircraft were used in combat missions during the Vietnam War (1955-1975).

Performance specifications for the XF-108 include a top speed of Mach 3 and a range of 1,150 miles. Weight (gross) is 102,000 lbs. A 4 x 20mm gun will be standard, along with support for 2.75" rockets, as well as the ability to bring supplies up to 4,000 lbs into service.

The cost of the program is $142 million. During its early design stages, the XF-108 was also considered for a bomber escort role - escorting a B-70 (XB-70) Valkyrie into enemy airspace.

This role was eliminated because the XF-108 lacked the necessary range to observe the B-70 to and from the target area.