AIRCRAFT ARMAMENT (non nuclear) BY E.H. ROUBAUD, Member.
At the Durrington Community Centre, 9th December, 1987.
Weapon Carrying
Contrary to earlier warplanes, to-days machines have multi-role capability. They can carry a wide range cf weapons attached to the same pylons on the fuselage or wings. They may be rockets, bombs, torpedoes, radar-pods, or fuel tanks, generally called “stores”. Guns are mounted in the fuselage. There may be between 2 and 8 wing pylons and 3 to 5 fuselage pylons. Swing wing aircraft as the Fll and Tornado have pivoted wing pylons that remain aligned parallel to the fuselage.
Dropping a Bomb!
For speeds of 500 m.p.h. or so a bomb must be forcibly ejected from its bay. Release under gravity alone can leave the activated weapon riding in the turbulent air just below the fuselage; when the bay doors are closed they pick up the bomb, leaving it loose in the bay! Downward opening bay doors create disturbed aero dynamic forces causing high stresses and difficult control of the machine. The Bucaneer is very rugged and has a rotating bomb door to which 4 x 1000 lb. bombs can be attached moving 180 deg inside the fuselage thus reducing the problem. All stores (any item attached to a pylon) are forcibly detached by an explosive charge.
Navigation:-
Military aircraft are packed with electronics, including inertial navigation systems which pinpoint the machine’s exact position so it can fly to its target without reference to outside sources. Data from this system is supplied to guided missiles before release from the plane to direct them to their targets.
Attachment and Ejection.
Each store is hunq from an ejector release unit on a pylon by means of two lugs screwed into the top. These engage with two hooks in the pylon facing opposite ways, fore and aft, closed manually. The hooks have an over-toggle mechanism locking very securely preventing any movement of the store in flight. Forces up to 8 gn must be withstood buffetting and aircraft manouevering forces are great. Release is by firing two cartridges inserted into a breach which is piped to cylinders with pistons to release the toggle and force the store away from the plane. They are detonated electrically.
Rockets
Have pods or release rails carried on pylons. They propel themselves away from the plane at about 1,200 m.p.h. The pods consist of a honeycomb of tubes each with a rocket of about 2.3/4″ dia. with folded fins, which are deployed on ejection. Each has a solid fuel motor. A latch retains the rocket in its tube until the motor developes a thrust of several hundred pounds. The interval between each rocket being fired is 5 to 10 milliseconds, to prevent collision on leaving the pod. They have to be “aimed” at the target by flying at it.
Guided Rockets – are larger – 10″ or more dia, and are carried on launch rails. Each is retained in position by a latch system as above requiring several thousand pounds of thrust to release it and clear the aircraft. The guidance system is “informed” and connected to the plane by an “umbilical” cable through a complex break-away connector. These need only be fired in the general direction of the target and will home in on it.
Guidance is one of-jour types. Radar beam riding cn a beam sent out from the weapon reflected from the target. Laser guidance depends on “illumination” from an independent point – a hillside or another aircraft. It is in short pulses and invisible to the human eye. Target definition is pre firing programming such as a map reference, using the aircraft’s navigational system. Heat seeking is the fourth.
Torpedoes and depth charges
These are usually programmed just prior to release, and usually deploy a parachute to enter the water without serious impact and at a reasonable angle. Torpedoes have target seeking facilities.
Bombs in two sizes for most purposes – 500 lbs. and 1,000 lbs. (actual weight fully equipped near 500 and 1200 lbs.) About half is weight of explosive, the rest the casing – about 1″ thick steel. They have 4 tail fins for stability in flight. For low level release a retarding tail is also fitted to ensure the aircraft is well clear of the target wnen contact is made! More sophisticated large guided bombs are also fitted with moveable fins at the front for guiding. The nose has a laser sensor to guide it to an “illuminated” target. It has no propulsion system, but the guiding fins are powered by a thermal battery. It was very effective in the Falklands War against gun emplacements.
Environment
Very severe buffetting and extremes of temperature0. – 60° C in some places on take-off and + 1400 deg C in flight in a very short time. Severe erosion if flying through rain, hail or dust. Bird strikes can be very serious. Nose cones with windows for radar beams etc. call for strong re-inforced plastic. High frequency vibrations beteween 2 and 5 KHz are encountered.
Testing & Trials:-
These are very comprehensive and require 2 or 3 years to complete – may well be the most expensive part of the entire development.
The value of all this was seen in the Falklands, where British weapons proved to be so reliable and effective.
