Monday, 18 November 2019

German Explosive Ordnance - Rockets (Part 3)







German Explosives





HS 293 A-1


Length Overall: 381.9 centimeters
Span of Wing: 310 centimeters
Span of Horizontal Stabilizer: 113.6 centimeters
Span of Vertical Stabilizer: 98 centimeters
Diameter of Fuselage: 47 centimeters
Diameter of Power Unit: 33 centimeters

Height Overall: 109 centimeters (approx.)
Average Chord: 79.3 centimeters (approx.)
Wing Area (Total): 2.4 square meters
Wing Loading (Launch): 441 kilograms per square meter
Wing Loading (Target): 390 kilograms per square meter
Weight of Warhead: 500 kilograms
Weight at Launching: 1045 kilograms
Weight at Target: 967 kilograms
Weight of Fuel: 78 kilograms

Maximum Velocity: 260 meters per second
Average Velocity: 230 meters per second

Maximum Range at:
2.2km Altitude: 4 kilometers
4.0km Altitude: 5.5 kilometers
5.0km Altitude: 8.5 kilometers

Radius of Turn: 800 meters
Designed "G": 3.0 g.




Description: The Hs 293 A-1 has principally an aluminum, stressed skin, spot welded structure.  The forward portion of the fuselage is structurally the bomb casing with an aluminum covering or fairing.  Fastened to the rear of the bomb is a vertical plastic beam (about 3/8 inch thick) which runs to, and is fastened to, the after portion of the fuselage.  The radio and the associated gear for the controlling of the bomb are mounted on either side of this plastic beam.  On the after corner of this beam is mounted a roller.  The after portion of the fuselage is a stressed-skin, semimonoque structure with a rail (for the aforementioned roller on the plastic beam) mounted on the top inside of the structure.  Quick disconnection fasteners are mounted at the connection between the rear of the bomb fairing and the forward end of the rear fuselage to be quickly detached and rolled off the bomb and plastic beam, giving quick and complete access to all of the control gear.  The wing and tail are aluminum and of the usual built-up type.



Aerodynamic Characteristics: The missile is controlled in roll by the normal type of ailerons on the trailing edge of the outer portion of the wing.  The ailerons also control the yaw effect.  It is controlled in pitch by the normal type of control surfaces on the trailing edge of the horizontal tail surface.



Control System: The control system consists of the following parts:

A. Receiving set E-230.  This unit could use any of the 18 channels, each of which were 100 kc apart in the band between 48 and 49.7 mc/s and could be changed easily in the field to satisfy the operation requirements for frequencies.

B. "Aufschaltgerate" for damping and smoothing the receiver signals.

C. Three-phase AC gyro for stabilization in roll and yaw.  It has a precession rate of 2 degrees per minute.

D. High resistance double potentiometer for proportioning the data.

E. 210-volt D.C. generator for the receiver.

F. A transformer with built-in relays to activate the aileron surface magnets.

G. Elevator mechanism with an "Oemiz" motor and potentiometer for returning the elevator to its normal position.

H. An iron nickel plate battery of 24 volts with approximately 14 amp/hours.


This missile, because of the type of intelligence used, is limited to use in good, clear weather and with air superiority.  It is subject to jamming, and this, therefore, may limit use to targets where jamming equipment is not installed.

A joystick type of control was used in the parent aircraft.  This control box made use of a very clever cam arrangement which gave proportional control.



Warhead: The warhead was constructed in one section of drawn steel.  The base plate was welded in position.  The nose filling plug was threaded and held in place by two set screws.  A kopfring was welded to the nose just behind the nose plug.  One transverse fuze pocket was located aft of the suspension lug.  A central exploder tube used in the explosive cavity to insure high order detonation of the warhead on impact with the target.




Operation

Upon locating the target, the carrier aircraft makes its approach to the trajectory distance, and in the last of its dive, sets a course such that the target can be seen 30 to 60 degrees to the right of the course.  Shortly before release time and particularly at the moment of release,t he carrier aircraft must be in a horizontal position.  At the time of release the aircraft must have a minimum speed of 334 km/hr if the He-111 is used, and 400 km/hr if the He-177 or the Do-217 are used.

The missile is released and directed to the target by the bombardier.  Immediately after release, the speed of the aircraft may be reduced, but the release altitude and direction should be maintained for a period of approximately 10 seconds.  After this interval of time, it is no essential to maintain release altitude and course direction.  It is important that any change in flight be done slowly and carefully so that the target remains on the side of the bombardier during the entire flying time of the missile.  The field of view of the operator and the freedom of the carrier plane in approach may vary according to the type of aircraft.  In all carrier planes, there should be a field of view of approximately 110 degrees to the right.  The flying time of the Hs 293 A-1 should not be greater than approximately 100 seconds.




Remarks

The Hs 293 is the outgrowth of the "Gustav Schwartz Propellerwerke" glide bomb which was first designed in 1939.  The further development of this glide bomb by Henschel represents their first attempt at a radio controlled missile.

The original Schwartz design was a pure glide bomb guided on a straight course by means of an automatic pilot.  The method of attack entailed high altitudes for the carrier aircraft in order that sufficient range could be attained and still be out of anti-aircraft fire.

Henschell took over the work of further developing this missile in early 1940, and it was decided to use some form of propulsion for the missile so that attacks at low altitude and increased range could be made.  The Hs 293 A-1 was the first model to be used operationally with the new motor.

In as much as all future models under development were very similar to the Hs 293 A-1, it will be the only missile of this series discussed in detail.  The following is a list of projects which emerged from the original Hs 293 A-1:


Hs 293 B: This was a wire-controlled version of the original radio-controlled series, designed to be used in the event of a jamming of the radio control mechanism of the original series of bombs.  The G.A.F. considered that up to 70 percent disturbance was permissible before a change-over to the wire-controlled series would be necessary.  Since these conditions were never attained, the Hs 293 B was never put into use.


Hs 293 C: This missile was a modified version of the Hs 294 and had a detachable warhead, etc., in the same manner as the Hs 294, but a conventionally shaped body.  The fuzes included an impact fuze with a short delay to allow for penetration in cases where the missile struck a ship above its waterline, an impact fuze which detonated immediately on impact after it had entered the water, and a fuze operated by a spinner which detonated the missile after a passage of 45 meters through the water.
 This subtype was designated the Hs 293 C during its development stage, but when large scale production was to start, it was changed to the Hs 293 A-2, and was to replace the original radio-controlled series for general purpose use against shipping targets.


Hs 293 D: This was a projected type of missile to be fitted with a television camera in the nose.  The camera was designed to repeat data back to the missile controller.  The camera was designed to swing vertically and was aimed in the line of flight by a small wind vane on the outside of the projectile.  As the projectile was rudderless, and in theory should not yaw in flight, there was no need to allow for any traverse in the camera mounting.  About 20 of these missiles were built and test flown, but the television gear proved unreliable, and the project was abandoned.


Hs 293 E: This was purely an experimental model built to try out a system of spoiler controls to replace the conventional aileron mechanism.  These controls were incorporated in the final model of the Hs 293 A-2, but were never employed operationally, since by the time the bomb was brought into large scale production, the G.A.F.  had no aircraft left for anti-shipping purposes.


Hs 293 F: This was a tailless missile which was never developed beyond the design stage.


Hs 293 H: This missile was intended to be released and controlled in flight by one aircraft and detonated by a second observing aircraft, which would be flying in position where it would be easy to observe the impact of the missile against the target.  The project was abandoned because it was felt that the detonating aircraft would be unable to remain directly over the target long enough to carry out its function.


Hs 293 V6: This subtype was developed for launching from jet-propelled aircraft at launching speeds up to 200 meters/second.  This involved modification of the wing span of the missile so that it could be carried within the undercarriage of the aircraft.  The Ar 234 aircraft was to be used as the parent plant, and since it was not yet available at the conclusion of the war in Europe, the missile never progressed beyond the design stage.







Next Time: Rockets (Part 4)


Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters

Monday, 4 November 2019

German Explosive Ordnance - Rockets (Part 2)







German Explosives





HS 117 "Schmetterling"




Design and Performance Data

Length Overall: 429 centimeters
Length of Fuselage: 369 centimeters
Span of Wings: 200 centimeters
Height of Vertical Rudder: 92 centimeters
Diameter of Fuselage: 35 centimeters

Weight (Empty): 150 kilograms
Launching Weight: 430 kilograms
Weight at Target: 175 kilograms
Weight of Assisted Take-off Units: 180 kilograms (90 kg per)
Main Power Fuel: 12.7 kilograms
Main Power Oxidizer: 59.2 kilograms
Compressed Air: 3 kilograms
Explosive: 25 kilograms

Maximum Velocity: 250 meters per second
Average Velocity: 240 meters per second
Maximum Range: 20 kilometers
Service Ceiling: 10.5 kilometers
Absolute Ceiling: 13 kilometers



Main Propulsion System

The main power unit is a liquid rocket with a pressurized fuel feed and a variable automatic thrust.

Main Power Fuel (Tonka): 12.7 kilograms
Main Power Oxidizer (Salbei): 59.2 kilograms
Compressed Air: 3 kilograms
Charged Weight: 159 kilograms
Weight (Empty): 80 kilograms

Total Launching Impulse: 14,000 kilograms per second
Main Thrust Unit Impulse: 12,500 kilograms per second
Total Impulse: 26,500 kilograms per second
Launching Thrust: 3,00 kilograms per second
Maximum Thrust of Main Unit: 380 kilograms
Minimum Thrust of Main Unit: 60 kilograms

Burning Time of Main Unit: 40 to 90 seconds
Maximum Combustion Chamber Pressure: 40 atmosphere
Average Thrust: 220 kilograms
Average Time of Burning: 57 seconds

Overall Length of Main Thrust Unit: 17 inches
Overall Diameter: 4 and 1/2 inches
Throat of Nozzle Diameter: 1 and 7/16 inches
Exit of Nozzle Diameter: 2 and 7/8 inches



Description: This missile, probably better known as the "Schmetterling", is a rocket propelled, radio-controlled, missile for use against bomber formations.  Some versions are for ground-to-air and some for air-to-air operations.  The fuselage is of the conventional type mounting a single vertical tail surface and a single horizontal surface.  The horizontal surface is mounted well above the center line of the fuselage.  The arrowhead wing is mounted on the center line of the fuselage.  The forward section of the fuselage is non-symmetrical in order to accommodate a proximity fuze and a propeller-driven generator.

This missile is launched from the ground from a simple two armed zero length rail launcher.  The two arms support the missile at the wing roots at about the center of gravity.  Two assisted take-off units are used for ground-launching, one above and one below the fuselage.  At the end of burning these ATO units are jettisoned by means of explosive bolts which throw them clear from the airframe.  The air launched version does not use ATO units but is simply dropped from a standard bomb shackle.

Some of these models are automatically homed and some are remote controlled.  A single gyro automatic pilot is used for stabilization.



Details

Airframe - Type and Description: The main units of the fuel system form the backbone of the fuselage.  At the forward end is the steel air flask nested into the forward end of an aluminum Salbei tank.  Next comes an aluminum casting through which passes the main wing spar, and which is also used to space the hydrocarbon tank further aft for the proper distribution of the C.G. of the fuel since it is desired to have the fuel C.G. coincide with the C.G. of the entire aircraft.  On the after end of the hydrocarbon tank another aluminum casting is bolted which supports the main propulsion unit and the air stabilizer structure.  All of these tanks and castings are securely bolted together, forming the entire backbone of the aircraft.  This structure is covered with sheet aluminum.  The nose section, also formed of aluminum, is screwed to the forward end.

The wing and tail are built-up sections consisting of a cast magnesium frame with an aluminum covering.  The case magnesium wing frame is extremely light in weight and is rigid.


Airframe - Aerodynamic Characteristics or Peculiarities: This missile is controlled in roll by spoilers of the trailing edges of the wings.  These spoilers work out of phase with one another.  Yaw is controlled by the trailing edge spoilers on the wings.

Spoiler control was used for this model because, as in other missiles, it gave adequate and easy control as compared to other systems and produced less drag.  The spoilers also present a much more simple method of control than other systems.

This missile is rather unique in that assisted take-off rockets are place both above and below the fuselage mounted in the vertical plane of the center line of the fuselage.  It is also interesting to note the extent of asymmetry of the forward portion of the fuselage.  It was considered by the designer, Prof. Wagner, that horizontal asymmetry would be less harmful than vertical asymmetry, the asymmetry being necessary to correctly place the generator propeller and the fuze.

For reasons of stability, the missile, upon ground launching, makes at least one complete roll about its longitudinal axis.  If at the end of this roll the air speed is not great enough for adequate stability, it will make a second complete roll.  Seldom, however, is the second roll necessary.  This roll event is built into the control equipment and is entirely automatic.  During launching, the acceleration is about 8g.



Operation

Because aerodynamic characteristics at high speed change rapidly with small changes in speed, to make the control problems as simple as possible, it was decided that the speed of the missile should be held as nearly constant throughout the flight as was practicable.  This was accomplished by automatically regulating the thrust output of the main jet in relation to the velocity of the missile, 240m/s, being the arbitrary average velocity.  This regulation was accomplished by balancing the two pressures taken from a pitot static tube across two opposed aneroid barometric elements which, in turn, by means of electrical contacts, actuate an electric motor which operates a fuel control valve limiting the flow of fuel to the combustion chamber.  A constant proportion of the two reactants entering the combustion chamber must be maintained at all times at a ration of 2 parts nitric acid to 1 part hydrocarbon.  If one or the other of the reactants is allowed to collect in the combustion chamber an explosion will occur.  The nitric acid is also used to cool the nozzle.  It flows into the cooling jacket at the after end of the nozzle and then flows forward and enters the combustion chamber where it meets the hydrocarbon.  No ignition apparatus is necessary as these two fuels are self-igniting.

Professor Wagner was not satisfied with the motors which were developed by Dr. Sbyrowsky of BMW, feeling that they were too heavy.  Dr. Conrad, of the Berlin Technical High School, had been obtained by BMW to improve the motor design.  Dr. Conrad was experimenting with un-cooled liquid fuel motors for this project and at least two forms of combustion chamber material had been tried; one a form of graphite and the other a material built up of many layers of a very pure ceramic material such as silica or alumina.  These showed considerable promise and might have been incorporated in later designs.  Other liquid fuels were also being considered.  By means of various refinements it was hoped that the missile speed could be raised from a Mach No. 0.75 to 0.8.

Both reactant tanks are built of aluminum and are carefully machined.  The outside casting is bored so that a closely fitting piston (without rings) will slide in it.  In operation the liquid side of the tank is initially full, forcing the piston against the head.  As air enters the head, the piston travels to the right, forcing liquid out of the tank.  The object of this design is to insure that when the tanks are less than half full no slugs of compressed air are fed down the reactant pipes as the aircraft performs tight maneuvers.  Although the motor would re-ignite after stopping, a collection of one of the two reactants would cause an explosion.  On the forward side of the air bottle is a connection to which is T'ed a filling plug and pressure gauge which reads up to 250kg/sq.cm.  The bottle is charged with air to 220 atms.  On the aft connection to the bottle is a diaphragm which is punctured by an electrically fired squib.  The outlet from this connection leads to a regulator which delivers air to the two reactant tanks at 40 atms. (590 lbs/sq.in.)  On each side of each reactant tank there is a diaphragm valve which is blown when the 40 atms. pressure appears at that point.  This is done to prevent any possible contact of the reactants during storage or handling, and also to insure that both fuels enter the combustion chamber at the same time in order to prevent an explosion.  At full thrust, nitric acid enters the combustion chamber through 16 holes, and the hydrocarbon through 8 holes of equal size.  The thrust regulation is obtained by the aforementioned regulator motor, operating (through a gear train) a rotary valve plate which blocks off the holes limiting the amount of fuel which can enter the combustion chamber (fuel pressure being constant) and also maintaining the fuel ratio of 2 to 1.




Control System

This missile at first mounted a Friesecke & Hoptner receiver which operated at about 6 m.  The equipment was considered as too complicated and heavy for the missile and consequently was superseded by a further development of the "Staru" radio receiver for the Hs 293.  This new receiver was of the super-regenerative type having a much smaller form factor than the previous Hs 293 receiver, and was designated the E230-3.

For controlling the missile, the controlling ground station sends out a high-frequency signal which, by modulation with a lower frequency and appropriate keying, conveys to the missile directions for altitude, or elevation, and azimuth.  By referring to its gyro the missile is able to interpret and follow these signals.  On the ground, the signals are manually initiated by means of a "joy-stick" control which sets the pitch and yaw directions for the missile to follow, and which the missile will follow until the position of the stick is changed.

On the ground, the courses of the target and the missile are followed by means of an optical sighting device.  From observations with this device, missile course corrections are set which will bring it to the target.  No homing devices had been applied to this missile, although they had been discussed and were under development in several firms.  Professor Peterson of AEG had been working for some time on a universal radar ground computer for guiding flak missiles to their target.  RIM wanted Wager to incorporate this in the Hs 117 control, but he wished to keep it in its original simple state.  In the future he intended to develop homing devices to supplement his visual control for use in thick weather.  It is reported that Wagner would have liked to have this missile beam-guided to a radar followed target, but he felt that German radar was too inaccurate for the job.

Various developments for the radio control of this missile were being carried out be several firms.  Some work was being done in the range from 20 to 40 centimeters.  These frequencies were desirable since they could be beamed and were interfered with less by the jet than the longer wave lengths.  Shorter wave lengths were not considered, since suitable tubes were not developed.  In some cases, jet interference could be reduced by changing reactants.  In all cases solid powder gave the most trouble.  It was considered that Telefunken was doing the best work in radio control.  They were concentrating on 40 cm.

The electrical power for this missile was delivered by a propeller-driven generator located in one of the two noses of the missile.  On the ground, before launching, this same generator was driven by a motor in an outside power source.  During this period the propeller did not turn as it was provided with a three ball free-wheeling cam device.

The missile is stabilized about its longitudinal axis only by one gyro.



Limitations of the Control System

The only apparent limitation of this missile lies in the fact that it cannot be seen and consequently followed in overcast weather.  If homing devices, other than optical, were incorporated, this limitation would no longer exist.



Warhead and Fuze

Warhead: Considerable divergence of opinion existed in the RIM on the effectiveness of warheads with blast effect only as against fragmentation or incendiary pellet filling, but when the tests of the Hs 117 had been completed in the summer of 1944, the first series was ordered in August of that year with a blast effect warhead weighing 25kg filled with "Trialen" which was manufactured by Wasag at Reinsdorf near Wittenberg.


Fuze: It was intended to use a proximity fuze whenever developed and available.  The performance specifications for the fuze required operation between 6 to 10 meters.  It was intended that a small clock work arming device would arm the missile about 10 seconds after take-off.  Another device is incorporated, probably working off of the control gyro, which explodes the main charge if the missile rolls over on its back in flight, in which case all controls would be revered, making the missile uncontrollable from the ground by an operator who would not be aware of this condition.  Another timing device was incorporated which operated 120 seconds after launching to destroy the missile.



Auxiliary Equipment

This missile is equipped with two assisted take-off units, one above and one below the fuselage, each provided with nozzles offset at an angle such that the lines of thrust intersected at about the C.G. of the aircraft.  In launching, the lower booster is fired first, thus forcing the missile upward and forward off the launcher which is a simple two-armed cradle supporting the missile at the wing roots (zero length rails).  There is a 2 and 1/2-meter firing lanyard, which fired the top unit automatically.  Both units then burn until their powder is burned out by which time the main jet has been ignited and takes over.  Each assisted take-off unit has a total weight of 90 kg and contains 40 kg of powder charge.  Burning takes place from the inside out only since the outside is treated with "Polygon", a plastic preparation which prevents burning on the surfaces to which it is applied.  

The booster thrust totals 3,500 kg lasting for about 4 seconds.  It burns at a rate of about 5.8 grams per second.  This thrust brings the missile up to a speed of about 240 m/sec.  These boosters units are known as SG (Schmidding Geraet) 33.  They were developed by Schmidding in Bodenbach, and used powder made by Wasag, located near Wittenberg.  At the end of the booster burning time, the boosters are jettisoned by means of a powder charge and piston device.  Also under discussion as a method of dropping the boosters was a device which depended upon the reduction of the pressure within the booster unit itself.




Launching Device

This missile is launched from a simple two-armed cradle which supports each wing at its root in such a  way that an upward and forward motion of the projectile will carry it free from the launcher.  There is no movable dolly on this launcher.  The launcher is manually aimed in elevation and azimuth in response to signals received from a fire-control point.  Sighting devices for the launcher were contemplated but were never incorporated.








Next Time: Rockets (Part 3)


Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters

Monday, 28 October 2019

German Explosive Ordnance - Rockets Introduction and Part 1







German Explosives





German Rockets



Introduction


General

The value of the rocket as a weapon of war has been proved during the conflict of the past 5 years.  Even with the vast amount of work that has been done on the rocket during this war, there is a great deal of work still to be done in perfecting it.  During the past few years research work in this field has brought about the following improvements over the old types:


1.  The accuracy has been increased by rotating the projectile.  This is effected by using skew venturi.  The rotations developed range between 1,000 and 1,500 r.p.m. and considerably reduce the deviations of the projectile due to the influence of the wind.

2.  The range has been increased by using a greater weight of propellant in addition to the development of a new powder: Nitrodiglycol.  This new powder is more efficient than black powder and results in greater range and less smoke formation on firing.


3.  Multibarrel projectors carrying up to 42 rounds have been developed by the Germans to effect a greater rate of fire.  Reloading these new projectors is carried out mechanically.


When these first new efforts proved successful, great new exertions were made on the part of the Germans to develop more effective rocket weapons: rocket-propelled depth charges, anti-tank weapons, anti-aircraft rockets, flares, and aircraft bombs with rocket propulsion were tried out; and at the peak of the research program came the radio-controlled long range rocket which was still under development at the end of the war in Europe.



Solid Fuel Rockets

The following is a brief resume on the construction of the rocket at the beginning of this war.  The rocket motor consists of the combustion chamber sealed at one end and the base plate which threads into the open end of the combustion chamber.  The base plate has a series of holes in it, some of which are parallel to the axis of the rocket and some of which are inclined 45 degrees to the axis.


Propellant.  The propellant used at this time is the solid nitrodiglycol type.  Its advantage lies in the high calorific value and smokelessness, also in the slow rate of burning.  Its density is 1.5 kg/m^3, which is less than black powder, but this is compensated by the higher calorific value.  The range for an 8.6 cm rocket using this type of propellant is 1,200 meters.  Maximum velocity is 200 m/sec with a burning time of 5 seconds.  This is not considered very good performance and so the rocket is used only against low level attacks.

As long as long range is not required, powder may be used for rocket propulsion.  It must, however, be remembered that powder rockets are heavy (heavy combustion chamber) and that the charge/weight ratio is small.  An attempt might therefore be made to develop powder rockets o flight construction, by using some arrangements for reloading the combustion chamber so that a larger weight of propellant may be carried.  This should increase the range.  Experiments on these lines have been carried out in Germany, but it was found that in order to insure reliable operation, the constructional complications became very great.  This reduces use of the main advantages of rockets - less weight and simple construction.


Stabilization.  The foundation for the method of stabilization was the spinning shell.  By placing the ventureis askew to the main axis of the rocket produced a sufficient spin.  This action gives rise to a gyroscope effect and tends to resist all external disturbing forces.  This method has given very good results and is greatly superior to the fin stabilization, which is inherently subject to wind errors.



Liquid Fuel Rockets


The liquid fuel rockets are superior to power rockets as regards to:

1. Weight ratio of the propellant carried.
2. Greater energy available in the liquid propellant.


Liquid Propellant.  For example, when 5 gm of powder is required for an impulse of 1 kg/sec, only 0.3 to 0.4 gm of hydrogen-oxygen mixture is required for the same impulse.  It will be seen that there is, in this case, a vast difference in the energy content of the propellant, moreover, the density of the liquid fuels is far greater than that of powder.  The time of burning is increased, greater velocity is reached, and altogether the advantage lies in much lighter construction, i.e., deadweight of the rocket, since the fuel and oxygen containers can be made of thin steel sheet.  The combustion chamber also becomes lighter.

However, the load on the combustion chamber becomes a problem, because of the greater energy and therefore higher temperatures; but this problem was solved.  Combustion temperatures for powder rockets are approximately 980 to 1,000 degrees Celsius; they are 3,000 to 4,000 degrees Celsius for oxygen-hydrogen mixtures, and in addition there is the boiling point of the mixture, the boiling points for hydrogen and oxygen being 253 and 183 degrees Celsius respectively.  These temperatures make severe demands on the material, and it is necessary to look for new alloys which can withstand these demands.

It is, of course, possible to consider other fuels than a hydrogen-oxygen mixture, e.g., petrol, benzol, methyl alcohol, petroleum, spirit, etc., together with liquid-oxygen.  These fuels have the advantage of a high boiling point and do not require special materials for the tanks; these are only needed for the oxygen.



Fuel Tanks.  For the hydrogen and oxygen containers, for example, it is possible to use an alloyed steel, covered with a thin lead coating; if the rocket is to be used only once.  At low temperatures (-183 to -253 degrees Celsius), all metals except copper become hard and brittle; however, copper remains ductile even down to such temperatures, and is therefore the best material to use for the fuel tanks.

The containers for liquid fuels at temperatures lower than -160 degrees Celsius are best made spherical (e.g., V-1), since this form offers the greatest strength.  They must be insulated, but this offers no difficulties.







PC 1400 FX Radio-Controlled Glider Bomb


Overall Length: 130 inches
Length of the Control Unit Housing: 16 inches
Length of Fins at the Root: 31 and 5/8 inches
Length of Fins at Outer Edge: 18 and 1/4 inches
Length of Fin Leading Edge: 18 and 5/8 inches

Max. Width of Tail Unit: 48 inches
Min. Width of Tail Unit: 33 and 3/4 inches
Span of the Fins: 58 and 3/4 inches

Weight of Filling: 270 kilograms
Total Weight: 1,650 kilograms (approx.)



General Description: The PC 1400 FX is a radio-controlled glider bomb designed for attack against capital ships or similar targets.  The complete missile consists of three distinct units: the H.E. armour piercing warhead, the control unit housing, and the tail assembly.  There are four aluminum alloy fins secured ot the missile at approximately the center of gravity.  The purpose of these fins is to give the bomb sufficient lift so that the control surfaces in the tail unit can exercise adequate influence.


Warhead: The warhead is an ordinary PC 1400kg bomb to which four above-mentioned fins have been attached.  It has one transverse fuze pocket located aft the H-type suspension lug.  Two horizontal exploder tubes are centered in the warhead to insure high order detonation on impact.  The usual filling for the warhead is 50/50 amatol.


Control Unit Housing: The control unit housing, made of cast magnesium alloy, is attached between the base of the H.E. warhead and the tail unit.  This space contains the gyroscopes, radio receiver, power source, and a small demolition charge for destruction of the control unit.

There are two gyroscopes mounted 90 degrees to each other in the after section of the control unit.  These two gyros control the stabilizing flaps on two of the tail surfaces.

The directional apparatus consists of the radio receiver and the servo motors which take the impulses from the radio.  The power source is a 24-volt battery.  This equipment operates four control surfaces measuring 8 cm by 1 and 1/2 cm, which are located on the trailing edge of each of the four fins.  These control surfaces are actuated in pairs; two of them control the lateral direction of the bomb, and the other two, its trajectory.

The demolition charge consists of approximately 1 and 1/2 pounds of penthrite wax.  It is fuzed usually with the VZ 80 "all-ways action" fuze.  The main purpose of this charge is to destroy the directional equipment in case the fuze for the main charge in the warhead fails to function.


Tail Unit: The tail unit consists of an inner cast magnesium alloy tail cone fitted with two long and two short case magnesium alloy struts.



Operation.   Bombing with the PC 1400 FX is carried out in conjunction with the Lotfe 7D bomb sight.  The only extra duty of the operator being to switch on the gyroscope of the bomb some 2 minutes before the moment of release.  The aim of the bombardier is taken the same way as in ordinary bombing.  AS the bomb is released, the aircraft is throttled back and put into a climb with the flaps down.  This action is to insure not overshooting the missile.  Once the requisite reduction in speed has been effected, the pilot flattens out.

At this time, corrections in the course of the missile can be taken if necessary.  At the moment of release, the bombardier starts a stop-watch going.  The bomb cannot be controlled during the first 15 seconds after release.  On the 16th second, the operator takes control of the missile.  It has been estimated that the missile can be guided with a margin of error of only 50 meters from an altitude of 7,000 meters.

The bomb takes 42 seconds to reach the ground from 7,000 meters, and 38 seconds from 6,000 meters.  The lowest possible height for satisfactory release is 4,000 meters.  At the moment of impact, the bomb, dropped from 7,000 meters is said to have a velocity of 270 meters per second.





Next Time: Rockets (Part 2)


Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters

Monday, 21 October 2019

German Explosive Ordnance - Containers (Part 5)







German Explosives





AB 500-1B Container


Overall Length: 80 inches
Tail Length: 29 inches
Tail Width: 17 inches
Diameter of Body: 18 inches
Filling: 28 SD 10 FRZ bombs


Colour and Markings: Markings on container - 28 SD 10 FRZ


Construction: The AB 500-1B container is similar to the AB 500-1.

The 28 SD FRZ bombs are accommodated in the central compartment of the container, 15 bombs being accommodated in the rear portion and 13 bombs in the forward portion.

Bombs are loosely packed nose to tail and are not secured by bands.






ABB 500 Container


Overall Length: 69.6 inches
Body Length: 25.2 inches
Body Diameter: 18.4 inches
Wall Thickness: 0.05 inches
Filling: 133 1-kg incendiaries, 2,200 "crow's feet"
Total Weight: 152.4 kilograms


Colour and Markings: Inside and outside of container is painted a dull slate grey.  There are two red bands; one is around the midsection of the bomb body, and the other is around the nose of the bomb.

Letters "ABB 500" are stenciled in black at center of bomb between the fuze pocket ad the suspension lug.

Letters "1941 bbZ 170 7" appear on tail fin.


Construction: The body is cylindrical shaped similar in appearance to a SC bomb except for the nose, which is more blunt.  The bomb is divided into two halves longitudinally and united by a rolled joint.  The vanes and other fittings are welded.  A loading hatch is screwed to the body just forward of the fuze pocket.  There is only one fuze pocket which is 7 and 3/4 inches in depth.  Fuze pocket contains one annular picric acid pellet fuze and a wooden cylindrical packing piece.


Operation: The aerial burst action of the fuze and picric acid pellet splits the case in half down a weak weld.


Suspension: Horizontal.


Remarks: The bomb container is a C 500 flam casing adapted to carry approximately 133 1-kg incendiary bombs.  Among the 1B's found, in one container were some chalk cement rods (with a wire core) 1.9 inches in diameter (possibly used as filling pieces.)






"Streubrand C 500" Container

No picture available

Overall Length: 69.5 inches
Body Length: 18.8 inches
Tail Length: 24.5 inches
Tail Width: 25 inches
Filling: 1,200 green celluloid incendiary boxes immersed in water.



Construction: The Container is similar in appearance and dimensions to the ABB 500 Container, with the exception that the loading hatch is absent as in the AB 500-1.

A 7/16 inch internal diameter steel tube, welded to the upper half of the casing directly above the longitudinal joint of the two halves of the container, connects at right angles to the side of the fuze pocket to which it is also welded.

A single length of green detonating fuze leads from this tube to turn along the longitudinal joint and run round the nose of the container, returning via the junction of the tail to enter the 7/16 inch tube.  At intervals along the longitudinal joint steel clips are placed to secure the detonating fuze firmly in position.

The two halves are hermetically sealed together by welding at the longitudinal seam.  Inside the container is a steel strut, which is used to give support to the two halves of the casing.  The strut is weakened in one place.

Screwed to the fuze in the normal way is a standard gaine projecting into a wood packing piece.  One end of the detonating fuze is housed in this packing piece to contact the side of the gaine.

On release of the container, the fuze is charged.  After a short delay, the fuze fires, firing the gaine which in turn detonates the detonating fuze.  Detonating wave travels round the seam of the container to separate the two halves.  The weak part of the internal supporting strut is broken and the two halves are parted.


Remarks: The Streubrand C 500 appears to have been an inefficient incendiary weapon, and the method of separating the two halves of the container may have been found to be unsatisfactory in practice since damage to exposed detonating fuze would result in failure.






Mark 500 Boden Container


Overall Length: 69.6 inches
Body Diameter: 18.4 inches
Wall Thickness: 0.05 inches
Tail Length: 24 inches
Tail Width: 2 inches

Filling: 9 or 15 single candle flares and 6 SD 2 bombs.


Color: Slate grey or black overall.  Stenciled between the fuze pocket and suspension lug:

Mark 500 Boden
6 SD



Construction: This container is similar to the AB 500.  The tenth flare normally carried in the ABB 500 has been replaced by a subsidiary container for 6 SD 2 bombs.  Instead of the usual opening device, the container is opened by means of a continuous strand of detonating cord (green with pink filling, thought to be penthrite) which circumscribes the container at the junction of the two halves.

The subsidiary container for the 6 SD 2 bombs is anchored by the double wire cable to the U-shaped bracket positioned in the lower half of the body to one side of the internal suspension strip.  The 6 SD 2 container is formed along the longitudinal axis in two halves, retained by the two steel female end caps drilled at the side to admit the thin container securing wire.  Secured to each end cap is a U-shaped bracket, a 0.25 inch round bar, to which is attached the double wire cable.

After the 6 SD 2 container falls free, it is arrested by the double wire cable.  The jerk is so applied to the end cap that it suffices to break the securing wire and the end cap is pulled off.  The bombs then are free to fall away.


Suspension: Horizontal.






AB 1000-2 Container


Overall Length: 123 inches
Body Diameter: 26 inches
Wall Thickness: 0.075 inches

Filling:
-620 1-kg 1Bs; or
-246 1-kg 1Bs and 234 2-kg B.2 EZs; or
-372 2-kg B.2 EZs


Color and Markings: Light khaki overall.

Markings on body:

AB 1000-2
B.1.3 EZ
B 2 EZ



Construction: The body is T-shaped in cross section.  The longitudinal axis of the container is formed by two sheet steel plates 26 and 1/2 inches by 70 inches.  Indented together with circular spot welded pressings and welded along their greater dimensions to two U-shaped girder pieces.  Two circular sheet steel plates form the nose and tail bulkheads.  A slightly domed sheet steel nose is welded to the nose bulkhead and is reinforced by a tubular steel sheet approximately 8 inches long welded to both the bulkhead and the domed nose.  A sheet steel top plate is welded to the upper U-shaped girder to form an arc-line canopy extending 13 and 1/2 inches on either side of the girder.  The top plate is recessed to receive the H-type suspension lug and to accommodate the fuze pocket.

The central support for the tail unit is a steel bar welded to a square plate which in turn, is riveted to the tail bulkhead.  A flanged circular sheet steel plate is spot welded to the tube and tail cone for added support.  The tail fins consist of two layers of sheet steel pressed together, each layer being part of the adjoining quadrants of the tail cone.  Fuzes are housed in a thin sheet steel box inside the tail cone and are welded to the tail bulkhead.  An inspection hatch in the tail gives access to the fuzes.

On the under side of the fuze box are two steel clips which accommodate the 4 ounce penthrite charge provided to destroy the electromagnet generating units attached to the bottom end of the fuze.  Five sections containing incendiary bombs can be arranged in each side of the center bulkhead of the container.  Each section is separated by semicircular sheet steel separator plates.  The bombs are held in place by five sheet steel retaining bands which are drawn tightly around the bomb and container by turnbuckles.  Each strap is held in position at the lower edge of the vertical position by a large split pin anchored to a bracket support which carries a small charge consisting of two detonators.  Two rectangular steel plates near the nose hinge outward when the forward band is severed and form air brakes.

The fuze pocket accommodates the charging head from which six orange colored cables are led to the fuzes.  Two of the cables are connected by a fuze charging attachment to the head of the (89) B fuze; the remaining for cables are connected in pairs to two bayonet joint charging attachments housing the (69) D fuzes.  Six leads pass from the fuzes to a junction box in the tail unit.  Leading from the junction box are three cables for each of the six points (five retaining bands and the destroying charge on the steel fuze box), plus six black colored cables, all of which are enclosed in a green cover.  Four of those leads branch off to each of the five retaining bands (two wires to each det.) and four leads branch off to the self-destroying charge.

All detonators on the (89) B fuze circuit are instantaneous while the detonators on the (69) D fuze circuits have delays varying from 1 to 6 seconds, the variance between detonators being 1 second.  They are so placed that the 1-second delay is on the band nearest the tail unit, the 2-second delay is next, etc.  The 6-second delay detonator is used on the self-destroying charge of the fuze box.  On release, an electrical charge is imparted to one of the plungers of the charging head, depending on which of the fuzes is to be used.

The fuze functions and ignites a black powder pellet which drives a piston forward.  A projection of the piston strikes a soft iron core in the center of a coil of copper wire enclosed within a magnetic sheath.  The rapid displacement of this iron core induces an electric current in the coil which is passed to the junction box and then to the detonators which sever the bands.

Containers can be dropped from low altitudes with the (89) B fuze and instantaneous detonators used to secure a heavy concentration of bombs, or containers can be dropped from high altitude with the (69) D fuze and varying delay detonators used.  This would give a wide dispersion of the bombs.



Suspension: Horizontal.







Message Tubes (Sea and Land)


Sea
Overall Length: 14.75 inches
Body Diameter: 2.6 inches
Total Weight: 2.25 pounds



Land
Overall Length: 15.75 inches
Body Diameter: 2.0 inches
Total Weight: 1.5 pounds


Color: Yellow overall

Markings:
Meldebusche (land)
                Unegefahrlich (not dangerous)
                              Wechtige Moldung (important message)
                         Sofort Weitergeben (forward at once)


Construction: The sea message tube is made of aluminum and is painted yellow.  The top is closed by a disc with a friction igniter through it.  The igniter has a red top and a delay pellet giving a delay of 1 second.  The aluminum smoke container is below the igniter.  It contains a reddish brown powder, the surface of which has a black powder charge to start the burning of the smoke mixture.  The container is made watertight by tightening the wing nut.

The smoke container is 5.4 inches in length, has a diameter of 1.75 inches and weighs 0.75 pounds.

The land message tube is made of aluminum and is painted red.  The top cover holding the red-topped friction igniter (1-second delay) is a push fir over the container.  Through a hole in the cup-shaped aluminum piece near the cover protrude the ends of four strands of quickmatch.  These strands run down the side of the smoke container and meet several pieces of fire quickmatch below the smoke container.

When ignited, the reddish brown powder gives off a very bright yellow smoke.  The smoke container is 5 inches in length, has a diameter of 1.75 inches, and a weight of 10.3 ounces.












Next Time: Rockets - Introduction and Part 1


Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters

Monday, 30 September 2019

German Explosive Ordnance - Containers (Part 4)







German Explosives






BSB 360 Incendiary Bomb Container

No picture available

Overall Length: 7 feet 9 inches
Body Length: 1 foot 8 inches
Wall Thickness: 0.06 inches
Filling: 320 1 kg 1B's
Total Weight: 435 kilograms


Colour and Markings: Black overall


Construction: The BSB 360 is a sheet steel cylinder with a blunt nose and tapered tail section.  The cylinder is divided into four compartments, each containing eight bombs.  The two doors of the container are opening manually by a cable, each door opening two compartments and releasing bombs in groups of 180.  This container generally remains in the aircraft after dropping the load.


Suspension: Horizontal. Container retained in plane.






BSB 700 Incendiary Bomb Container

No picture available

BSB 700
Overall Length: 10 feet 3 inches
Body Length: 2 feet 2 inches
Wall Thickness: 0.06 inches
Filling: 702 1 kg 1B's
Total Weight: 900 kilograms


Colour and Markings: Black overall.

Stenciled on body:

Betadezant 700-5
Leengewicht 205 kg
Gesamtgewicht 900 kg


Construction: The BSB 700 is a sheet steel cylinder with a blunt nose and conical tail section.  The cylinder has six compartments, each containing 117 bombs.  The contents of each compartment are released by means of trap doors operated from an axial spindle, the release mechanism being controlled electrically through a solenoid.  Bombs are released in batches of 69 and 48 from each compartment.  Each compartment has an expendable outer door and inner rotating door (rotated by action of the solenoid).  This container remains in the aircraft after dropping the load.

Suspension: Horizontal. Container retained in plane.






BSB 1000 Incendiary Bomb Container


Overall Length: 8 feet 11 inches
Body Length: 2 feet 2 inches
Wall Thickness: 0.09 inches
Filling: 570 1 kg 1B's


Colour and Markings: Light khaki or grey overall.  "Leerewicht 210 kg" is stenciled on the body.


Construction: The BSB 1000 has a sheet steel cylindrical body.  The blunt nose and conical tail sections are attached by bolts and rivets.  The nose and tail sections are recessed to take a transport loading bar.  The main body is internally divided along its longitudinal axis by a hollow central bulkhead which houses the release rods.  Each half of the main body is further divided into 5 compartments by bulkheads, thus making 10 compartments.  Ten spring loaded compartment doors are hinged to the underside of the container.  These doors are held by hook releases which are connected by the release rod to the electrical release units fitted with manually operated release switches for use in loading.  No fuze is fitted and it is assumed that the electrical lead passes into the junction box and selection mechanism housed in the tail, the latter functions to space the 570 bombs as desired.

In operation, the electrical charge passes through the junction box and causes the selector mechanism to function.  Current is passed to release units, and these open the release hooks through the medium of the release rod.  The weight of the bomb forces doors open and bombs fall, the spring loaded doors then closing the preserve streamlined containers.  This container also remains in the aircraft after dropping the load.


Suspension: Horizontal. Container retained in plane.






AB 500-1 Container


Overall Length: 80 inches
Body Diameter: 18 and 7/8 inches
Wall Thickness: 1/8 inches
Tail Length: 28.75 inches
Tail Width: 24 and 3/8 inches

Filling:
-37 SD 10A; or
-392 SD 1; or
-184 1-kg incendiary; or
-28 SD 10 FRZ; or
-116 2-kg incendiary.


Color: Light khaki overall

According to contents, the following stenciling is found on the body:

AB 500-1
Fur 184 B1.3EZ
Fur 116B ZEZ
89B
69E

AB 500-1
37 SD 10A
Gew 47 kg
69E
89B

DB 500-1
392 SD 1
Gew 415 kg
89B
69D



Construction: The container is divided along its longitudinal axis into two halves hinged at the tail.  The nose compartment contains the fuze assembly, the central compartment accommodates the bombs, and the tail compartment being empty, forms part of the tail structure.  A metal strip is welded to one-half the container and forms a spigot for the two halves to close on.  A pressed metal plate having a central channel runs the length of the central compartment.

The internal structure varies as to bombs carried.  When SD 10 FRZ bombs are carried, they are loosely packed.  Fifteen bombs are carried in the rear of the central compartment and thirteen forward.  They are not secured by bands.  Containers for SD 10A bombs are divided internally into two compartments.  The central compartment of the container is divided into two halves by a plywood sheet.  Eighteen bombs are accommodated in the forward half and nineteen bombs in the rear half.  Each cluster is secured by steel bands which clip into the channel on one side and are wedged in by the wood strip.  On the other side the bands are secured together by split pins which pass through loops at the ends.  Metal strips looped around the steel bands split the pins.  Wooden packing blocks are recessed to receive the bands.  In the forward compartment the cluster of bombs is divided by slats of wood and the suspension strut.

The sheet metal tail fins of each half are braced by a bar welded between them.  The charging head Ladekopf MVOV 500-1 is housed in a steel block welded to the container wall about midway down.  A four-core electric cable from the charging head to the nose is carried in a metal tube welded to the inner wall.  The cable enters the nose compartment through a hole drilled in the forward bulkhead.  The fuze pocket is located in the nose by two brackets and welded to the forward bulkhead and sides of the container.  The lower end of the pocket receives the anvil retained by the shear wire.  A tubular extension to the anvil is arranged to receive the bolt, which secures the closed container after assembly.  Welded to the side of the fuze pocket is a short length of tube which contains the Z 69E fuze; the bayonet fitting three pin plug closes this tube and connects the fuze with the charging head.  A Zt (89) B fuze is held in the fuze pocket by usual locking and locating rings and is connected to the charging head by a charging attachment.  Access to the fuze assembly is gained by a hole cut in the wall of the nose, and closed by a cap having a bayonet fitting.



Operation: On release from the aircraft, an electrical charge is transmitted via the charging head to either or both fuze.  After a predetermined delay, depending on the fuze selected, the fuze operates to detonate the bursting charge.  This overcomes the shear wire and forces the anvil from the fuze pocket.  The two halves of the container swing back on the hinge and the contents spill out.


Suspension: Horizontal.


Remarks: In containers filled with SD 1's, the 69D has been painted out and a wooden plug replaces the 69D fuze.






AB 500-3A Cluster Adapter


Overall Length: 31 and 1/4 inches
Body Diameter: 16 and 1/2 inches by 17 and 3/4 inches

Filling:
-4 SD 50 kg; or
-4 SK 70 kg; or
-50 kg and 100 kg French bombs.


Color and Markings: Khaki overall.  Stenciled in black on body: AB 500-3A.



Construction: The cluster is built around two longitudinal channel plates 1/8 inch thick.  They are pressed into splayed U-shaped channels at the top and the bottom of the assembly respectively and joined together by two steel plates which form a central longitudinal bulkhead with a double wall.  Triangular plates welded between the bulkheads and the outer ends of the upper channel act as stiffeners.

At about the middle two plates, forming the bulkhead, are then shaped to form a rectangular compartment.  It is presumed that when German bombs are carried this compartment contains a junction box and charging attachment for the Rheinmetall fuzes mounted in the bombs.  Holes are punched in each side of the compartment and are shaped to take fuze head attachments.  A hole is drilled in the top main supporting plate to enable a connecting cable to be threaded through the bulkhead.

At each end of the top channel a pair of shaped steel crutch pads are pivoted on either side of the plate.  They are to fold over the top bombs and act as pressure plates for steadying brackets in the aircraft bomb rack.

Wood packing, shaped like saddle pieces for the bombs, are clipped to the sides of the central bulkhead.  Two wide thin sheet steel carrying bands are hinged to the top channel and locked into the bottom channel by the release mechanism.  Each band is in two halves coupled by an adjustable right and left handed screw which functions as a turnbuckle.  Suspended from the nose of the top channel is a rigid structure of steel strip in the form of two inverted Y's.  This is presumed to carry a locking device for mechanically armed nose fuzes, mounted in French bombs.

The container has an electropyrotechnic fuze of the 69 series.  A Ladekopf charging head is mounted on a steel pressing, welded within the top channel towards the rear end.  An electric cable passes from this, through the central bulkhead to the 69 fuze which is mounted on the side of the release mechanism, within the bottom channel.  A second cable may be connected to a junction box within the rectangular compartment, when the container is loaded with German bombs.

A rectangular pressed steel box is secured to the end of the suspension bar, within the bottom channel, by a nut.  Steel box angles slotted to engage round the bar, and which are riveted to the loops, slide into one another and beneath the steel box.  The loops are hinged to the bottom of the carrying bands.  Steel wedges are riveted to the reverse sides of the loops to keep the assemble wedged within the channel.  Small steel triangular boxes are welded tot he bottom of the carrying bands to facilitate release.  The assembly is locked while there is upward tension on the suspension bar.

On either side of the assembly, two brackets are welded within the channel.  A third bracket supports the fuze pocket.  A steel pin, attached to the remote end of the fuze pocket is threaded through holes drilled on the bracket and locks the suspension bar and assembly in the "up" position should tension on the bar be released.  When the container is released from the aircraft, an electric current is pressed via the charging head to the 69 fuze.  After a set delay the fuze fires, forcing off the remote end of the fuze pocket, which carries the locking pin with it.  The tension on the carrying bands then forces the suspension bar down and the locking assembly is released.

When German bombs are carried, a second circuit from the charging head passes the electric current, via a junction box, in the central rectangular compartment, to the Rheinmetall fuzes in the bomb.






Next Time: Containers (Part 5)


Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters