Cruise Missile Carrier Aircraft (CMCA)
The Boeing 747 was considered by the U.S. Air Force as a Cruise Missile Carrier Aircraft during the development of the B-1 Lancer strategic bomber. It would have been equipped with 50 to 100 AGM-86 ALCM cruise missiles on rotary launchers. This plan was abandoned in favor of more conventional strategic bombers.
The concept of a standoff launch and attack capability has been around almost since the beginning of flight. Wilbur Wright and Hap Arnold worked on an unmanned vehicle as early as the Great War. By the 1970s the United States apparently enjoyed a significant advantage over the Soviet Union in the development of cruise missiles. This advantage could be exploited by continuing current programs for both air- and sea-launched cruise missiles.
Aircraft developed specifically for cruise missile launch roles would carry a large cruise missile payload. Using the cruise missile instead of a penetrating bomber to strike targets not allocated to ballistic missiles, reveals that an all stand-off force would require a new aircraft to act as a cruise missile carrier.
Proponents of cruise missile carrier aircraft maintained that these bombers would be capable of performing the same missions as the B-l, including destruction of unlaunched Soviet ICBM, at a lower cost. However, U.S. cruise missiles were not expected to achieve high probabilities of destroying heavily defended targets. Further, Soviet long-range interceptor developments could reduce the ability of cruise missile carrier aircraft to cover the relevant Soviet strategic force targets. For these reasons, the B-l would be preferred if high survivability and substantial capability to destroy very hard targets are desired.
Secretary of Defense Harold Brown testified on 25 January 1979 that "I consider the cruise missile carrier aircraft to offer a prudent option for rapid growth in our strategic capability should it be needed. On this basis, the Air Force is completing concept/ system definition studies based on the consideration of both military and civilian aircraft. These aircraft include existing wide-bodied transport aircraft as well as the B-1 design, Advanced Medium STOL Transport (AMST), C-141, C-5A and other candidates. Upon completion of these studies in July of this year, two aircraft will be selected for follow-on advanced design/ development and flight demonstration. The concept feasibility flight demonstration of these two aircraft will occur not later than the Spring of 1981 to allow, if needed, a full scale engineering development decision in July of 1981."
The USAF had contracts with several different aircraft companies to investigate the feasibility of modifying off-the-shelf transport aircraft for use as cruise missile carriers. This included the Boeing 707, 747, the C-141, C-5 and L-1011 and DC-10. The nuclear powered cruise missile carrier aircraft (NuCMCA) concept provided unique strategic capabilities.
The cruise missile carrier aircraft raised concern among certain Members of Congress. The Senate version of the Department of Defense fiscal year 1979 authorization bill contained an amendment requiring that an arms control impact statement be prepared and submitted to the Congress for the cruise missile carrier aircraft before any of the authorized funds for the program could be obligated or expended.
Approximately 30 combinations of missile bay configurations and candidate Cruise Missile Carrier Aircraft (CMCA) were identified and studied. The missile bay configurations were grouped into four categories related to missile bay shapes and launch techniques. All but one (the conventional bomb bay) represented new cavity configurations and flow conditions not addressed by the available literature.
While this option had obvious advantages, the transport aircraft modified to the Cruise Missile Carrier Aircraft (CMCA) configuration would be exposed to harsh acoustical environments that have not been considered previously. One environment of concern is cavity oscillation during missile launch. The entire fuselage interior (or a fraction thereof) will be subjected to two different phenomena -- shear layer oscillation and acoustic resonance within the cavity enclosure -- combine to cause cavity oscillation.
The concept of using transport type aircraft did not lend itself to the Air Force's desire to have a launch aircraft with good escape characteristics, nuclear hardening, offensive and defensive avionics, long range and heavy payloads. In addition, the concept of using as wide body aircraft to carry between 48 and 90 cruise missiles, yields such a lucrative target that one might expect the enemy to put forth a great deal of effort to destroy it before it reached its launch point.
Rotary missile launchers provide for the internal storage of a relatively large number of missiles in a confined space and provide the ability to precisely position the weapon for ejection. This layout allows the use of a smaller weapon bay than would be required when using conventional bomb racks. As a result, the opening in the fuselage need only be slightly larger than that of the individual missile. The problem is that even a small opening will allow a considerable amount of air turbulence into the weapon bay, especially if the aircraft is at near sonic or supersonic speeds. The turbulence can cause high structural loads to be placed on the missiles, the launcher itself and any hydraulic and/or electrical equipment located within the weapon bay. Another problem is the dramatic increase in the radar cross-section of the aircraft, along with an increase in aerodynamic drag when the weapon bay doors are open.
One present design provides the capability of converting present known wide-body type of military or commercial passenger and freighter airplanes, to use as missile carriers and launching platforms, with a minimum amount of structural modification and weight penalty being absorbed by the carrier aircraft.
The missiles are carried on rotary racks which are transferred longitudinally along either side of the wide-body fuselage on longitudinally parallel tracks and at both ends of the fuselage a rotary rack is transferred laterally across to the tracks on either side, such that the missile racks move in a continuous carousel on the deck of the missile compartment.
When a rotary rack is in position adjacent a launch door opening in the aft side of the fuselage, a missile is ejected from the rotary rack through said opening in an outward and downward direction through the downwash from the wing and to avoid the empennage surfaces. When the rack of missiles is emptied, it is moved laterally across the fuselage to the tracks on the other side and another fully loaded missile rack is moved into the launch position.
Electrical power and conditioned air are supplied to each rotary rack through an individual unbilical cord connected in sliding relation to an overhead supply duct. The umbilical cord comprises an electric cable and air duct, having a quick-disconnect plug at the missile attachment connection; and serves to connect a source of conditioned air and electrical power to the equipment inside the missile for control and test purposes, while the missile is still in its launching rack or operatively dependent upon the mother plane.
An object of the design is to develop a cruise missile carrier from the present known wide-body type of jet aircraft, such as the Boeing 747, the McDonnell Douglass DC-10, and the Lockhead L-1011, which would offer an increased payload capability over current missile carrying military airplanes and yet not pose a high cost factor or severe weight penalty so that the airplane's performance capability can be retained.
Another object is to keep the configuration of the wide-body type airplane as basic as possible, by reducing the amount of major structural changes and thus reducing cost and weight penalty to the airplane.
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