German Explosive Ordnance - Rockets (Part 11)

German Explosives

Great Enzian

Description

The Enzian was conceived as a ground to air flak weapon.  Its secondary purpose was that of an air-to-air weapon.  Models E-1, E-2, and E-3 were the test and experimental articles.  All flight tests were carried out with the E-1.  The E-4 was the production design using an improved rocket motor, designed by Dr. Conrad instead of the Walter biliquid used int he earlier designs.  As the foregoing is the only major difference in the four models, they will be discussed as one: however, there exists another type, E-5, which being a basically different type will be covered in a separate report to avoid confusion.

The E-4 is a flying wing design of striking similarity to the Me-163.  Its total weight is 1,800 kg which includes the weight, 320 kg of the four assisted take-off units.  The warhead's weight is 500 kg.  The airplane is constructed of wood, having an overall length and span of four meters.  It attained its velocity of 300 m/sec with a main thrust unit delivering 2,000 kilograms initially decreasing to 1,000 kilograms during the flight.  Duration of power was 72 seconds, resulting in a vertical range of 16,000 meters and a horizontal range of 25,000 meters.

The four assisted take-off units deliver a combined thrust of 6,000 kilograms for 4 seconds, giving the missile which attains an end speed of 24 m/sec and an acceleration of 3.6 g from a launching ramp 6.8 meters in length.  The assisted take-off units are jettisoned after 5 seconds.

Although it was anticipated that E-4 would be used as an air-to-air weapon with slight modification, principally reduced fuel load, all experimental flight testing had been done from ground to air.  A standard 88 mm gun carriage was adapted for use as a launching platform by the simple addition of two iron rails 6.8 meters long.  A traverse of 360 degrees and a vertical firing arc from 0 to 85 degrees were obtained.  Air launching of the device was routine; i.e., dropping free from underneath the parent aircraft flying in the direction of the target.

The speed on leaving the launching rails is 24 m/sec; to avoid the possibility of stall no control is applied until the flying speed has reached approximately 55 m/sec.  For practical purposes an elapsed time of 5 seconds is allowed between the triggering of the launching mechanism and the first control signal.  The Enzian, as were practically all German guided missiles, was directed to the target vicinity by radio control.  When the target approach was within the range of the homing device, the latter took charge of the missile's final run in.  Coincidence or line of sight navigation was used under favorable conditions; however, several methods were accepted for night or reduced visibility use.



Airframe


The Enzian E-4 airfram was a flying wing type having no horizontal stabilizer and a fixed vertical fin.  Control was effected through trailing edge flaps which act together as elevators and differentially as ailerons.  The basic dimensions are as follows:


Length: 4 meters
Span: 4 meters
Maximum Diameter (Fuselage): 0.88 meters (Circular cross section)

Root Thickness: 20% root chord
Tip Thickness: 10% root chord
Wing Area: 5 square meters
Airfoil: NACA symmetrical; no twist.
Dihedral: Zero
Chord Root: 1.25 meters
Chord Tip: 0.98 meters
Sweepback: 30 degrees

Weight (E-4 Complete): 1,800 kilograms
Empty (including Warhead): 833 kilograms
Warhead: 500 kilograms
Motor: 97 kilograms
Fuel: 550 kilograms
Assisted Take-off Units: 320 kilograms
Airframe (including Control Gear): 333 kilograms


For the purposes of an air-to-air missile, the fuel weight was reduced to 150 kilograms and the assisted take-off units discarded.

The airframe was designed to be built of wood because of current metal shortage, but provisions were made for conversion to metal stampings.  The production process was to use hot plate gluing methods for fabricating a pressed or plywood material.



Aerodynamic Peculiarities and Characteristics


Aerodynamically, the E-4 appears normal.  Its stability in flight tests was accepted as good.  The E-4's design performance follows:

Maximum Velocity (Design): 300 m/sec
(Measured Walther Motor): 240 m/sec

End Speed Launching: 24 m/sec
Minimum Speed for Safe control: 55 m/sec

Vertical Range: 16,000 meters
(Measured Walther Motor): 7,000 meters

Horizontal Range: 25,000 meters
Turning Radius: 500 meters



Propulsion Unit


Although the Walther power plant was originally intended fo rthe Enzian and was used in the test flights, it was entirely unsatisfactory and replaced by the Conrad motor.

The bifuel liquid rocket motor uses Salbei (92% HNO3 + 8% H2SO4) and Visol, the ratio of weights being 1.4 to 1.  The total quantity of fuel, 550 kg, is exhausted in 72 seconds during which time the thrust is reduced from its initial 2,000 to 1,000 kg at the end of burning.  As pressure reduction between the air bottle and liquid tanks is through a simple orifice plate, the progressive reduction in the combustion chamber operating pressure is the direct result of the air bottle's gradual exhaustion.  Equal pressure is applied to both liquids and metering is effected by the resistance of the connecting pipes and not that of the nozzles.  The total impulse (108,000 - 110,000 kg sec) corresponds to a mean S.I. of 199; however, Wurster states that the mean propellant consumption 5.5 gm/kg sec rises to 5.6 at start and end of burning operation and that the S.I. is of consequence approximately 182.

Although the mixture, Salbei and Visol, is spontaneously inflammable, the Enzian motor used an electrically ignited powder starter in the combustion chamber to effect ignition.  This system had the advantages of smoother ignition and less risk of explosion than spontaneous combustion.  A further precaution against explosion was taken by starting the Salbei feed first by shortening its supply pipes and setting its bursting disks at slightly lower pressure than those of the Visol system.

The propulsion unit's arrangement, dictated by C.G. considerations, as follows: (1) Air bottle; (2) Visol tank; (3) Salbei tank; (4) Combustion chamber.  The air flask was originally inflated to a pressure of 200 atmos.

The liquids are retained in their tanks by means of bursting disks selected to rupture at 15 atmospheres at entry and 36 atmospheres at exit.  All tanks are made of mil steel 2 mm thick and no corrosion treatment, enamel, or protective coating was employed as the only General Staff requirements was that the containers should withstand 6 months storage after being filled with Salbei and fuel.

The weights of component parts of the motor are as follows:


Combustion Chamber: 24 kilograms
Air Bottle: 19 kilograms
Spherical Tank: 30 kilograms
Spherical Tank: 24 kilograms; 97 kilograms
Fuel Weight: 550 kilograms

Effective S.I. Fuel and Motor = 199 x (550/647) = 170

Relative to use of an air pressure fuel feed system versus a turbine-pump system, Wurster states that according to German figures, the former is lighter up to impulses of 200,000 kg/secs and has the additional important advantage of requiring no time for running up to speed.  He cited the Me-163 which requires 4-5 seconds to run the turbine up to its operational speed of 30,000 pointing out that such delay is prohibitive for a flak rocket.


Intelligence and Control Systems


Operationally it was expected to use the Enzian in the following manner:  Launch it toward and direct it to the target vicinity under radio control using the new German equipment Kogge and either line of sight or radar navigation.  When the missile's approach to the target came within the operating range of the particular self-seeking head employed, the latter would assume control and direct the Enzian to the target's proximity on a modified homing course.  The proximity fuze at pre-determined distance activates the warhead which was designed to ensure maximum coverage and effective damage of the target from 45 meters.

It is considered pertinent to note here that the Germans were doing extensive research work on the theory of homing courses.  Their principal investigations appeared to be based on compromises lying between a pure chaser or homing course and a straight interception route procured by interjecting self-navigation into the intelligence system

Initial planning provided for the Enzian's use of one of several typo homing devices and proximity fuzes currently being developed or combinations of the above.  Tests had not progressed beyond operation with the standard German radio control, the 6-meter "Strassburg-Kehl", developed by Telefunken and Strassfurt Rundfunk.  The "Kogge" designed by Telefunken to operate on a 24-cm wave length was destined for use in the production Enzians.

The I.R. device, "Madrid", developed by Kepka of Vienna, an acoustic device developed by Telefunken and Messerschmitt, or an electronic device were projected for use as homing heads.  These articles had been laboratory tested by their manufacturers only as separate entities.

Metamorphosis of the internal control system from two axis stabilization involving the use of four gyros to acceptance of one axis stabilization using a Horn gyro having two gymbal rings is outlined above under experimental testing.  Standard Siemens electric servos are used to actuate the control surfaces.



Warhead and Fuzing


Three types of wrhead of equal weight, 500 kilograms, were projected for the E-4.  The type which seemed to have accrued the most favor among the Messerschmitt engineers and the local flak officers was built up of a metal shell or container 1.5 mm thick.  The shell was lined with cylindrical pellets cast of mild steel 20 by 30 mm containing an incendiary core!  The explosive cast into the resulting cavity contained a booster charge and fuze in its forward end on the longitudinal axis.

Tests of the above type warhead showed that it could be expected to put 1.5 pellets in an area of 1 square meter at a range of 65 meters.

The second type of warhead incorporated 550 small rockets driven by gunpowder which had been developed by one of the SS laboratories and were to be used as part of the armament of the Me-262.  The rockets were mounted in the warhead to fire forward in a 30 degree cone from a maximum range of 300 meters; their effective range, however, was 550 meters and at that range each rocket was considered capable of destroying a bomber.

The third type warhead was straight explosive dependent only on concussion to destroy the target.

Both proximity and self-destruction fuzes were provided.  The proximity fuzes were projected on the I.R., Electronic, and Acoustic principles; however, the latter had essentially been dropped by the designers as the maximum range at which the actuating impulse was of sufficient magnitude was too small to derive most effective results from the warhead.



Auxiliary Equipment


Four powder jets assisted take-off units delivering a total of 6,000 kilograms thrust for 4 seconds are used to launch the Enzian.  The JATO's produced by Rheinmetall-Borsig weigh 80 pounds each.  They are attached by explosive bolts which release the cases by firing at the end of burning.  Small wings fitted to the JATO's assist in the jettisoning.

Next Time: Rockets (Part 12)

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

German Explosive Ordnance - Rockets (Part 10)

German Explosives

Feuerlilie Model F-55

Description

The F-55 is another of the Feuerlilie series of rocket-propelled guided missiles which the LFA (Luftahrtforschungsanstalt Hermann Goering E.V.) located at Volkenrode/Braunschweig, Germany was developing in order to obtain aerodynamic data in the transonic region.  Although the primary purpose of the Feuerlilie series development work was to obtain aerodynamic test data, there is evidence that a certain amount of thought was being given to the possibility of using the F-55 as a weapon.

The Feuerlilie F-55 has a fuselage 4.8 meters in length and a diameter of 55 cm.  The wing span of the two main fins which are attached to the afterbody of the fuselage is 2.6 meters.  The first F-55 had a solid propellant rocket drive, but later models used a liquid rocket motor with a dry powder assisted take-off unit.

The F-55 was to be ground launched and it was expected to reach an altitude of 4,800 meters with a maximum horizontal range of 7,500 meters.  Elaborate plans were also being made to install telemetering and to follow the flight path of the missile by cine-theodolites.

History of Development

Development work on the F-55 was started about May 1944 by Dr. Gerhard Braun of LFA.  The body for the F-55 was built by Ardelt Werke, Eberswalde, Breslau.

The production scheduled for experimental models of F-55 for the year 1945 called for a total of 35 with deliveries of at least 3 per month for the first 10 months of the year.  These were to be tested with various stabilizing systems and the later models were also to be equipped with telemetering and remote control equipment.

The first model of F-55 with solid propulsion was tested at Leba, Pomerania in May 1944, with satisfactory results, a Mach number of 1.25 being attained.  The second model with a liquid fuel system and take-off unit was tested at Poenemunde on 11 December 1944; this model went into a spin about its pitch axis shortly after leaving the launching track.  The third model had been sent out to Poenemunde for testing, but had not yet been tested.


Conclusions

Since the Feuerlilie F-55 was primarily a research project, it is of interest largely from the standpoint of the methods tried and the techniques of flight observations used.

As the F-55 like the F-25 was a manifestation of the Velkenrode research groups' ideas, it undoubtedly represents a high order of an aerodynamic development and requires treatment as such.  The Braunschweig documents, duplicated by the United States Army Air Forces and evacuated to Wright Field, Dayton, Ohio, include comprehensive reports on the Feuerlilie series.


Details

Airframe

The airframe of the Feuerlilie F-55 consists of a fuselage 4.8 meters long, and having a maximum diameter of 55 cm.  There are two sharply swept back wings having a span of 2.6 meters.  Two vertical fins are mounted at the extremities of the wings, this position being chosen to keep them out of the wake of the body.

The outer halves of the training edges of the wings are movable so as to give aileron control.  No rudder is provided, yaw control being obtained from aileron action.


Power Plant

The power plant used for the first model of F-55 was the RI 503 solid propellant type built by Rheinmetall-Borsig.  For the second and third propulsion unit designed by Dr. Contrad of DVX (Deutsche Versuchsanstalt fur Kraftfahrzeug und Fahrtzeugmotoren) located in Berlin.  In addition, an assisted take-off unit.  "Pirat," a solid propellant rocket was used.




Design Data

SG 20
Thrust: 6,400 kilograms
Time of burning: 7 seconds
Weight of fuel: 210 kilograms
Impulse: 45,000 kg/sec


Pirat ATO
Thrust: 10,000 kilograms
Time of burning: 2.7 seconds
Weight of fuel: 150 kilograms

Impulse: 27,000 kg/sec



Control System

On the first model of F-55, no roll stabilization was used.  On the second and third models, gyro equipment developed by Fischl of DFS (Deutsche Forschungsanstalt fur Segelflug) was tried.  This system used a single gyro with Askania pneumatic rubber servos.

It was expected that the rubber would provide the necessary mechanical damping, but due to the fact that the only test flight on which this system was used failed, it was impossible to determine whether or not this was the case.  On subsequent models, it was proposed to use a Horn gyro system consisting of two gyros, one of which was used for damping only.  This system was also to be used with the Askania pneumatic servo systems of remote control.

In connection with the Feuerlilie program, a new telemetering system "Stuttgart" had been developed which had 12 channels and gave 20 values per second with an accuracy of plus/minus 5 percent.  This system was designed by the Forschungsanstalt Graf Zeppelin, located at Stuttgart/Ruit.


Warhead and Fuzing

Since the F-55 was primarily a research missile in the early stages of its development, there was no provision made for a warhead.  Like the F-25, a Rheinmetall-Borsig time fuze was used to ignite the flares mounted on the wing tips to insure satisfactory tracking of the missile in flight by means of cine-theodolites.


Launching

The F-55 was launched from an inclined ramp built by Ardelt Werke, Breslay.  The launching angle was 20 degrees to the vertical.

Rheintochter

General Description

The Rheintochter is a radio-controlled anti-aircraft rocket designed for ground launching against bomber formations.  The first model Rheintochter 1, is a two-stage rocket having a total launching weight of 1,750 kg.  The starting rocket has a burning time of only 0.6 seconds, after which it drops off, the main stage then being automatically ignited.  Stabilization was achieved by six fins attached to the rear of the main body of the rocket and four fins attached to the starting unit.  The rocket was to be remote radio controlled with the possibility of using an infra-red homing device together with a proximity fuze to detonate the missile in the midst of the bomber formation.  The control surfaces were located at the nose of the missile.  It attained a final velocity of 360 meters per second, and could reach a height of 6 kilometers with a maximum horizontal range of 12 kilometers.

The Rheintochter 1 was replaced by the development of the Rheintochter 3.  The remainder of this discussion will be on the second model and will go into considerable detail.

In the Rheintochter 3, the rear take-off unit was dispensed with and replaced by two auxiliary take-off units mounted on the sides of the body of the rocket.  The main rocket stage could be either a liquid or a solid propulsion unit, depending on the availability of fuels.  The Rheintochter 3 is designated as R-3f when a liquid propulsion unit is used and R-3p when a solid propellant is employed in the main rocket stage.  The control and steering mechanism are identical in both Rheintochter 1 and Rheintochter 3.  The Rheintochter 3, however, is allowed to rotate about its axis in flight and instead of six stabilizing fins, it is provided with only four.

Details

Airframe

The Rheintochter 3 consists of a main fuselage 500 cm long and 54 cm in diameter, having four large swept-back main fins and two auxiliary take-off units mounted on the sides of the body between the two pairs of fins.  As in the Rheintochter 1, the control surfaces are mounted in the nose section but are of a somewhat different aerodynamic design. 

The main fin span is 220 cm, the four fins being attached to the body so that the angle between successive fins is 90 degrees.

As in Rheintochter 1, the main fuselage is constructed partly of aluminum plate, partly of steel alloy plate and partly of a material called ELEKTRON.  The fins were to be constructed of LIGNOFOL, a highly compressed laminated wood, but for mass production purposes, plywood could have been used.



Design Data


Length: 500 centimeters
Span: 220 centimeters
Diameter: 54 centimeters

Weight (Empty): 525 kilograms
Take-off Units: 440 kilograms
Main Stage Fuel: 88 kilograms
Main Stage Oxydizer: 336 kilograms
Main Stage Compressed Air: 18 kilograms

Explosive (Weight): 160 kilograms
Launching Weight: 1,570 kilograms
Weight at Target: 685 kilograms



Power Plant

A. R-3f Liquid Propulsion Unit: The R-3f liquid propulsion unit requires fuel tanks carrying 336 kg of Salbei, 88 kg of Visol and 18 kg of compressed air at a pressure of 250 atmos to provide pressure feed to the combustion chamber.


B. R-3p Solid Propellant Unit: The R-3p solid propellant unit utilizes 5 rods of diglucol dinitrate weighing 90 kg each, making a total weight of 450 kg.



Design Data (R-3f)

Launching Altitude: Angle
Total launching impulse: 105,000 kg/sec
Velocity at end of combustion: 410 m/sec
Velocity at target: 400-200 m/sec

Take-off units: 2 dry powder rockets
Take-off unit impulse: 25,000 kg/sec
Take-off unit thrust: 28,000 kg/sec

Main stage rocket impulse: 80,000 kg/sec
Main stage burning time: 45 sec
Main stage thrust: 1,700 to 2,300 kg



Control System

Since remote control radio roll stabilization was found to be unsatisfactory, it was decided that Rheintochter 3 would be allowed to rotate at the rate of one revolution per second about its longitudinal axis, just as X-4 rotates.  Since the X-4 gyrocommutator system for converting control impulses to the proper control surfaces in turn was available, it was thought that this system could also be used for Rheintochter 3.

The combination radar tracking and remote control system "Elsass" or possibly "Brabant", the decimeter version, was to be used for guiding the flight of the Rheintochter 3, just as proposed for Rheintochter 1.  However, the "Elsass" development was not far enough along to permit field tests to determine whether it was satisfactory.



Warhead and Fuzing

In the liquid propulsion version R-3f, the warhead is carried between the Salbei and Visol fuel tanks in that section of the main fuselage to which the main fins are attached.

In the solid propellant version R-3p, the warhead is located farther forward between the control compartment and the propelling charge.  The warhead consists of 150 kg of high explosive.

The fuzing system for Rheintochter 3 had not been finally decided upon.  Several plans were under consideration, all of which contemplated the use of a complicated fuzing system, which would not only serve to detonate the missile, but also take care of detaching the ATO units after one second and igniting the main jet.  In addition, of course, a time feature would be embodied to detonated the missile after 50 seconds in the air so that it would not fall and explode on friendly territory.  The Rheintochter 3 was also to be fitted with an impact fuze and a proximity fuze of some sort, either acoustic, infra-red, or radio.  Among the proximity fuzes considered were "Kranich", "Kakadu", "Marabu", "Fox", and several others.

As pointed out, plans were also under way to utilize some sort of homing device in Rheintochter, but these plans were still in a very nebulous state.


Auxiliary Equipment


Like Rheintochter 1, Wasserfall, and the other guided AA rockets, Rheintochter 3 requires a great deal of auxiliary ground equipment, such as computers, optical gear, range finders, etc, for remote control purposes.



Launching Equipment

The launching equipment for the Rheintochter 3 is identical to that used by the Rheintochter 1.

Next Time: Rockets (Part 11)

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

German Explosive Ordnance - Rockets (Part 8)

German Explosives

Wasserfall C-2

General Description

A. This flak rocket was given the name Wasserfall and the designation C-2 8/45.

B. The C-2 was designed to be launched vertically from the ground, and traveling at a supersonic speed to be guided into bomber formations where it would be exploded.

C. The Wasserfall resembles a half-size V-2 with small wings.  It has a similar motor and is launched in much the same manner.  Its control gear is also similar.

It could reach a maximum speed of about 770 meters per second in about 45 seconds after which time the speed would decrease as the fuel would be exhausted.  It could still chase targets until its speed had dropped to about 350 meters per second.  Its maximum fighting ranges were : 18 kilometers in height and 26 kilometers in horizontal range.  It was designed to withstand maneuvers of up to 4.4g.  The missile was guided by radio signals from the ground until approaching the target at which time a self-contained homing system was to lead it in.  It was planned to incorporate a proximity fuze to explode the weapon close to the bombers.

With these properties the Germans expected every other missile to bring down a bomber making 2g evasive maneuvers at a speed of 250 meters per second.

Operational Aspects

A.  The Wasserfall was planned for use from the ground against air targets, specifically bombers.  Suggested locations for launching sites were along the French coast and the approaches to major targets of bombers.

B.  The launching site requires much equipment and, although mobile, would thus be subject to attack.  Lack of maneuverability against relatively slow airplanes would have inhibited its effective use.

C.  The Wasserfall was expected to be both cheaper and more effective than ordinary flak for the results obtained.  Only operational use could prove this point.

Recommendations:  It is believed that an intensive study of the Wasserfall will yield much information on the principles and the use of a supersonic guided missile.

Details

Airframe

Type and Description:  In overall appearance the Wasserfall resembles a half-size V-2 with small wings.  The approximate dimensions are:

Length: 7,800 mm

Caliber: 880 mm

Wing Span: 1,890 mm

Tail Span: 2,500 mm

There are four small biconvex dorsal wings at the center of gravity to assist in making turns.  In line with these wings are four stabilizing fins at the tail.  Control surfaces are fitted on the stabilizing fins both in the air stream and in the gas stream of the jet motor.

Aerodynamic Characteristics:  The Wasserfall is designed to catch, while traveling at a supersonic speed, a target having a velocity of 250 meters per second doing 2g maneuvers.

Essentially the missile travels at and is designed for supersonic speed.  However, the transition from zero speed at launching to the supersonic range is not instantaneous and some additional control is desirable during this interval.  This is supplied by the gas stream fins which are present for the first 5 to 15 seconds of flight.  Once the supersonic range is reached the air stream fins supply sufficient control while the jet stream fins add a drag.  Consequently they are jettisoned at that time.

The missile is designed to stand maneuvers up to 4.4g.  The wings will support a light of 8,000 kg per pair to which the body, tail, etc, add about another 4,000 kg making a total lift of 12,000 kg.

The missile weighs about 3,500 kg at take-off, but the weight drops continually to about 1,500 kg by the time the fuel is exhausted.  Thus at take-off the lateral acceleration should not exceed 3g, increasing to 4.4g as the fuel is consumed.  To allow for this the control applied to the servo is made weak at first and is gradually brought up to its full power.

Wind tunnel tests of models made may be found in report No. UM 6013 dated February 1945 in the Goettingen documents.  Evidence obtained at the wind tunnels at Kochel shows that at least six different shapes have been tried out to get the best aerodynamic results.

Design Data: The missile is fabricated from mild steel to the shape shown above.  It may be broken down into the following parts:

1. Nose: contains the homing device (zielsuchendes Geraet) fuzes (Zuender) and explosive (Sprengstoff).

2. Nitrogen tank: (Druckluftbehaelter).

3. Visol tank: (Brennstoffhaelter).

4. Wings: (Fluogel).

5. Salbei tank: (Salbeibehaelter).

6. Control system: Mounted to rear of Salbei tank.

7. Tail: Supports motor (Brennkammer), tails (Flosse), air rudders (Luftruder), and jet rudders (Stahlruder).

Production Data: The following remarks apply to all parts of the missile.  The only production was by the Electromechanische Werke at Peenemunde for the developmental testing.  Estimates of this production range from 40 to 275 units.

Estimates were drawn up for the men, material, and space needed for the mass production of 5,000 monthly.

Propulsion System

Type and Description: A liquid jet motor drive is used with develops an 8,000 kg thrust for 45 seconds.  The motor burns a self-igniting mixture of Salbei (nitric acid) and Visol (a hydro-carbon mixture) in a chamber with a venturi nozzle.

Characteristics: 

Thrust: 8,000 kg

Total Impulse: 360,000 kg

Launching acceleration: 1.2 to 2.6 g

Final acceleration: Ca. 4 g

Fuel consumption: 41 kg/sec

Specific impulse: 180 to 195 sec.

Design Data: The general arrangement is indicated in the image at top.  The foremost flask contains nitrogen at a pressure of 200-300 atmos.  This flask is 8 to 13 mm thick and is not wire wound.  The compressed gas passes through a reducing valve to 30 atmos and is used to force the liquids out of their storage tanks.  This flask and the two storage tanks are made of rolled and welded steel.

The forward storage tank contains about 400 kg or 430 liters of Visol.  Visol is a rather variable fuel according to the ingredients available or the intended use.  A typical Visol mixture is: 40 percent isoprophyl alcohol; 40 percent vinyl ether; 2 percent water; 18 percent of four other ingredients including 1 percent of a dope to control the ignition delay time.

Visol is a contracted code name for vinylisobutylether.  A Diesel oil may also be used in place of Visol.

The rear tank contains about 1,500 kg or 1,100 liters of the oxidant Salbei.  Salbei is a mixture of 90 percent nitric acid (including 3 percent 2 water) and 10 percent sulfuric acid.  No attempt is made to make the acid water free as it would be reabsorbed from the air before it was ever used.  The sulfuric acid was added to prevent corrosion by the nitric acid of the steel available for the tanks.

As already mentioned, the fuel and oxidant were forced out be pressure.  The fuel is removed through a swinging pipe hanging down in the tanks.  As this pipe is subjected to the same acceleration as the fuel, its end is always covered by liquid.  This design gives a lightweight removal system which removes practically the last drop of liquid although the liquids are being swished around in the tanks.  It is said this system increased the maximum altitude obtainable by 4 kilometers over a pump arrangement that was tried.

Both fuel and oxidant are passed through a valving arrangement which introduces both liquids into the motor at the same time under full flow.  Valves in the various pipelines are opened simultaneously by explosive charges.  Just before each liquid enters the motor there is a diaphragm.  These diaphragms stop the liquid until it has built up to practically full pressure at which time the diaphragm bursts and allows a full flow of liquid, from the start, to enter the motor.

The ratio of liquids by weight is Salbei to Visol from 5 to 1 up to 8 to 1 depending on the actual Visol mixture being used.

The Visol is fed directly to the nozzle head.  The Salbei first apsses through the cooling jacket of the motor before going to the nozzle head.  In some cases some of the Salbei is also injected through cooling holes into the combustion chamber.  The two liquids ignite within 0.01 to 0.1 second after contact.  An expansion ratio of 2.5 to 1 up to 3.9 to 1 is obtained int he motor.  The gas exit velocity is approximately 1,850 meters per second.

Brennschluss (turning off of the motor) had not been settled.  Provisions were made for several methods, which were:

1. Letting the motor use up all of the fuel.

2. Turning off the motor by radio signal.

3. Turning off the motor at a pre-determined velocity by means of an integrating accelerometer.

Intelligence and Control System

Type and Description: Many systems were tried or proposed which, although radically different in details, ar every similar in function.  Three gyros are used to prevent oscillations about the three axes.  Remote radio control is used to guide the missile toward the target.  A homing device is to be used in the final part of the chase to guide the missile to within killing distance of the target.  Finally a proximity fuze is to explode the missile.  In addition there is a relay transmitter in the missile to enable the personnel on the ground to follow it.


Characteristics:  The control system must be capable of guiding the missile very close to a target which is making 2g curves at a velocity of 250 meters per second.


Design Data

1. Rudders and Rudder Machines:  In each of the four tail fins there is a pair of rudders in the air stream and the jet stream.  Each pair of rudders is driven by one all-electric servo motor.  The armature of the servo motor oscillates at 50 cycles a second to reduce the backlash to almost zero.  Roll control is applied to all rudders.

2. Gyros: Three course gyros are used to prevent the missile from oscillating.  The take-off cards on the gyros are positioned by the remote radio control to keep the gyros oriented with respect to the desired path.

3. Remote Control Radio Receiver: This unit receives command signals from the ground control station to direct the missile towards the target.  The "Strassburg" E230V is employed as the receiver.

4. Relay Transmitter: A transponder triggered from the ground radar to indicate the angle of roll of the missile by measurement of the polarization of the wave transmitted is known under the code name "Reuse".

5. "Mischgeraet": An electrical computing device which receives signals from the control radio and the gyro, mixes these signals, and sorts them out for the various rudder motors.

6. Homing Device: A device to make the missile home in very close to the target.  None had been sufficiently developed to test in the missile.  It is a pre-requisite as the ground control is not sufficiently accurate to guide the missile close enough to the target to do damage.

7. Power Supply: Batteries, invertors, regulators, etc., to power the control systems.

8. Warhead, Fuze, Firing Circuit: About 305 kilograms of explosive were to be used.  Of this, about 100 to 150 kg would be concentrated int eh nose.  The remainder would be distributed through the body much in the form of primer-cord.  This distributed charge was necessary to destroy the missile in mid-air as it would be used over friendly territory.  The warhead was expected to have a destructive range of 40 meters.

9. Auxiliary Equipment: The Wasserfall required considerable ground equipment for the remote control.  Equipment is required not only for the transmittal of control signals to the missile, but also to track both the missile and the target.  The missile is guided so that it is always on the line between the target and the ground observer. Preferably, the tracking is done optically.  In this case, the operator has only to keep the missile and the target lined up in the optical field.  However, radar tracking must be provided for the many times that optical tracking will be inadequate.  The radar tracking system and control system known as the "Elsass" consists of the following functional parts:

-Mannheim Radar - Radar set to track the target.  It also measured the distance between the target and the missile.

-Rheingold - The Rheingold follows the missile and measures the roll position of the missile by determination of the angle of polarization of the signals sent out by the "Reuse" relay transmitter in the missile.

-Indicator - The indicator displays information obtained from the Mannheim and the Rheingold:

-Azimuth and Elevation of target and missile.
-Distance to target and missile.
-Roll position of missile.

-Kehl Control Transmitter - An operator sits before the indicator and by means of a joystick control keeps the missile in line with the target.  This joystick controls the command signals sent out by the "Kehl" control transmitter to the "Strassburg" receiver in the missile.  By this transmitter the operator may also fire a fuze in the missile when his indicator shows the missile is at the target.

Next Time: Rockets (Part 9)

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

German Explosive Ordnance - Rockets (Part 7)

German Explosives

X-4

General Description

The X-4 is a fin-stabilized guided missile with a proximity fuzed warhead developed specifically for use by fighter planes against enemy bomber formations.

Stabilization is obtained by four large fins fitted symmetrically to the body and steering is achieved by rake spoilers operating in four small tail fins which are interdigitated with respect to the large fins.  In appearance, it is quite similar to "Fritz X" except that it is much smaller, the warhead weighing only 20 kg and the total weight being 60 kg.  It is launched without assisted take-off from fighter planes.  It can be either wire-controlled by an operator in the fighter plane or it can be used as a self-steering target seeker by the use of acoustic homing.  If it is wire-controlled, some sort of rocket propulsion is to be used; while if acoustic homing is used, it is proposed to dispense with the rocket propulsion unit.

Operational Aspects

The principal operational use of the X-4 would be for fighter use against large enemy bomber formations.  Of course, the wire-control version would necessitate the launching plane remaining in the vicinity in order to control the flight of the missile and this in turn seriously restricts its maneuverability.  On the other hand, if acoustic homing were used, the X-4 could be launched and the plane could immediately execute an evasive maneuver.

With the 20kg warhead, it is extremely doubtful that much damage could be done to a four-motored bomber at a distance of 15 meters, the operating range of the "Kranich".  The effectiveness would undoubtedly be increased if the power plant were dispensed with and the payload doubled, as would be the case if acoustic homing were used in conjunction with a plane of the ME 262 type, it would be quite a formidable weapon to counter enemy bomber formations, and could probably be used for other tactical purposes as well.

Details

Airframe: The airframe of the X-4 consists of a cylindrical body 190 cm in length and 22 cm maximum diameter on which are mounted four large plywood fins fitted to the midsection of the missile and four small tail fins in which the rake spoilers are mounted.  The main wing span is 58 cm.

Rotation about the longitudinal axis achieved by small trim tabs attached to the four large stabilizing fins.  These give a rotational speed of 1 and 1/2 r.p.s., which in turn is used to give greater stability in flight and also permits greater manufacturing tolerances in the entire assembly.  The main fins are swept back at an angle of 45 degrees, which gives a maximum air speed of 270 m/sec.  However, due tot he comparatively short range over which this weapon is to be used, it is not expected to attain a velocity of greater than 240 m/sec before it reaches the target.

Steering is effected by means of rake spoilers located in the tail fins.  These spoilers vibrate at a rate of 5 cycles per second, control being effected by making the period during which the spoiler projects from one side longer than that during which it projects from the other.  When the two periods are equal, no control is applied.  This method of steering has the disadvantages of appreciable drag and a certain amount of delay, but has the advantage of simplicity and instantaneous mechanical response.

Design Data

Launching Weight: 60 kilograms

Weight less Fuel: 50 kilograms

Wing Surface: 0.56 square meters

Wing Loading: 200 kg/m2

Maximum Speed in Horizontal Flight at 6,500 m altitude: 270 meters per second

Lateral Acceleration in Horizontal Flight at 6,500 m altitude: 40 m/sec2

Total Energy available during 33 sec Burning Time: 1,600 kg/sec

Power Plant

The Bi-fuel liquid propellant motor is the BMW 109-548 rocket motor using a mixture of Salbei (98 to 100 percent nitric acid) and Tonka 250 (57 percent crude m-xylidine with 43 percent triethylamine).  This motor is capable of delivering an initial thrust of 150 kilograms which drops to about 25 kilograms after 30 seconds.

The solid propellant which it was proposed to use was "Mixture 167" by Wasag.  Initial thrust is 120 to 140 kg which is also reduced to about 25 kg after 30 seconds.

Of course, there were also plans under way to eliminate the propulsion unit entirely, in which case the payload could have been appreciably increased.

Intelligence and Control System

In all the proposed versions of X-4, the missile rotates and therefore only one gyro is needed.  When wire control is used, the principal purpose of the gyro and commutator system is to translate the right-left and up-down signals into the proper pulses to feed to the rake spoilers in the tail fins.  The gyro is spun up while the missile is still attached to the launching aircraft.  During the flight of the missile, the gyro is not power driven.  The gyro was made by Th. Horn. Leipzig.

The wire control system consists essentially of a small joystick control unit mounted in the aircraft, a pair of control wires and a receiving unit in the missile consisting of a gyroscope and a pair of relays.  The control unit contains two drums which revolve at a rate of r.p.s. one drum controlling azimuth and the other elevation.  The control wires consist of 2 insulated single strand Swedish spring-steel wires of 6,000m length and 0.22mm diameter.  The receiving unit in the missile is quite simple consisting primarily of a polarized relay for azimuth control and unpolarized marginal relay for elevation control.  The polarized relay responds only to polarity changes in the direction of the current flow through the wires while the unpolarized marginal relay responds only to changes in the value of the current, regardless of its polarity.  In this way, both azimuth and elevation control signals can be transmitted simultaneously over the same pair of wires.

The relays are connected to the spoiler solenoids in the tail fins, through the gyro commutator system.  This arrangement converts the left-right and up-down signals into the proper pulses which are to be fed to the solenoids actuating the spoilers.  The power supply is a small 9-volt dry battery located in the afterbody of the missile.

During the flight tests, there were no detrimental effects from static electrical charges accumulating on the wires and the mechanical difficulties had been solved by paying out the wire from the bobbins on the missile and similar bobbins on the parent plane simultaneously.  Wire control was selected primarily because, compared to radio remote control, it is practically jamproof.

In March 1945, there was also under development a plan to dispense with the power plant and wire control and to use an acoustic homing system "Pudel" as the control device.  This system is based on the same fundamental principles as the acoustic proximity fuze "Kranich".  It consists essentially of a mica and 0.03 mm aluminum foil diaphragm connected to a carbon microphone, the output of which is fed to a single stage amplifier and relay output.  This assembly is mounted at an angle of approximately 60 degrees to the longitudinal axis of the body and the sound passes into the diaphragm through a series of wire mesh screens which serve to attenuate differences of air pressure due to rotation but not the sound of motors and propellers of enemy aircraft.  A small lyre arrangement is attached to the vibrating system in such a way as to broaden out the mechanical resonance curves of the individual components of the system.  The composite curve of the acoustic system with the 15-wire lyre attached is practically flat from 200 to 400 cycles.  The wire mesh screens attenuate the slow air pressure variations about 40 or 50 db, whereas the sound vibrations of 200 to 400 cycles are attenuated only 1 db.

As the X-4 rotates, if the missile is homing directly on the target, the output of the microphone will be constant and there will be no modulation output and consequently no steering corrections.  If the missile is not aimed directly at the target, there will be generated a modulation frequency of 1 and 1/2 cycles per second, the rotating speed of the X-4.  This modulation frequency of 1 and 1/2 cycles per second is used to transmit information to the spoilers through the gyrocommutator system.  For this purpose, the normal gyrocommutator system has been modified to some extent.  Only 8 models of "Pudel" have been built and so far no flight tests have been made.

The modification of X-4 with "Pudel" and also equipped with the "Kranich" acoustic proximity fuze when launched from a fighter plane of the ME 262 type appears to be a weapon of great promise, since after launching, the fighter pilot can immediately take evasive action.  The range of the acoustic homing device is expected to be about 1,000 meters, so that if it were launched at a range of 2,000 meters, the first 1,000 meters of its flight would be uncontrolled.




Warhead and Fuze

When X-4 was originally conceived, it was expected to use a 20-kg cast-steel warhead enclosing the explosive material.  However, due possibly to the shortage of steel in Germany at the beginning of 1945, some thought was being given to the use of an uncased molded plastic type of warhead which was to be attached to the afterbody by wood screws and had an adaptor for the nose fuze attached to the nose in the same way.

The fuzing system consisted of the acoustic proximity fuze "Kranich" which forms the nose of the missile, an impact and graze fuze, and a self-destroying fuze which operates 35 seconds after release.  The acoustic and impact fuzes are armed 7 seconds after release.  The acoustic fuze consists of a light diaphragm actuated mechanism which responds to the sound of aircraft propellers at a range of 15 meters.  This fuze has a time delay of 1/50 second to make it more effective.



Launching Devices


Originally the X-4 was being carried only by the Focke-Wolf 190.  However, it was later planned to use it also in connection with ME 262 and DO 335.  The missile is suspended from the parent craft by means of ETC70AI, which is a modified 70kg bomb rack with a 7-prong umbilical cord and provision for two control wires.  The X-4 is released electrically when the pilot presses the bomb release switch.

Next Time: Rockets (Part 8)

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

American Guided Missiles - A.A.F. Missiles (Part 2)

American Projectiles and Explosives



Missiles

A.A.F. Missiles

2,500-pound GB-4 Air-to-Surface Missile

Overall length: 12 feet 2 inches

Wing span: 12 feet

Overall height: 6 feet 2 inches

Body diameter: 24 inches

Total weight: 2,536 pounds

Warhead: 2,000-lb G.P. Bomb AN-M66


General: GB-4 is a glide bomb which is launched from an aircraft and guided by remote radio control to its surface target by employing television intelligence picked up by a television camera on the missile and radioed to a receiver in the launching plane.  It has a special plywood airframe built around a 2,000-pound bomb, with rudders and elevators but no ailerons.  The airframe is fastened to a magnesium casting threaded to the tail of the bomb.

The missile is effective against well defined point targets, easily distinguishable from the surroundings on a television screen, and has an average circular error of 200 feet.  At present, the weapon can be used only under good visual bombing conditions, but it has been proposed to incorporate radar tracking of the missile by the parent aircraft to alleviate the handicap.

It is launched outside the normal anti-aircraft range from either a B-17 or B-25 at 175 mph at a preferred distance of 17 miles from the target at an altitude below 15,000 feet.  With a glide ratio of 6 to 1, the time of flight, at average rates of 250 to 300 mph, is four minutes.


Control: The television camera mounted under the bomb is set to point along the bomb's flight path, the standard setting being 3 degrees below the axis of the bomb.  The field of view is 14 degrees wide and 18 degrees high.  The camera scans the area and modulates a transmitter with the picture which is broadcast to the parent aircraft.  The radio control signals are transmitted by a "liaison" transmitter in the parent aircraft and are received by a standard or command set receiver installed in the glide bomb.  A modulator installed int he airplane will put out any one of the five audio tones to modulate the transmitter.  The relays in the control unit switch current to the elevator servo motor and the rudder capstan motor to move the control surfaces in the desired directions.  In addition, two more relays are actuated to shift temporarily the gyro pick-offs either to the right or to the left when those signals are given.  The missile is stabilized by a directional gyro to give roll and azimuth control.


Suspension: The missile is carried outside the plane on a Shackle D7.  Electrical cables, connected to it, pull out on release.


Destructor: The Destructor T9 is placed in the control box and is actuated, on impact, by the Fuze T62.







2,500-pound GB-8 Air-to-Surface Missile

Overall length: 11 feet 7 inches

Wing span: 12 feet

Tail: 4 feet 8 inches

Total weight: 2,555 pounds

Warhead: 2,000-lb G.P. Bomb AN-M66


General: This is a radio-controlled glide bomb, with flare observation, designed for use on large installations.  The wing is covered with plywood and is bolted to the boom assembly.  The two spar booms are of solid poplar and have hinged bands attached to their front ends which secure the bomb to the frame.  The elevator is covered with metal to prevent damage by the flares.

The GB-8 should be launched with the parent plane on a bomb run when the target is at bombardier's angle of 75 degrees - which is still outside normal A.A. range at altitudes from 10,000 to 15,000 feet.  It will glide at speeds varying about 6 to 1 depending on the elevator setting.


Control: The guiding system consists of a radio control link from the plane to the missile, servo connections to the control surfaces, gyro stabilization, and a flare panel of five Flares T3 and T4 (white and red) for observation.

Control surfaces are the ailerons on the wings, the elevator surface, and a single rudder on the left vertical stabilizer.


Suspension: The missile is carried outside the plane on a Shackle D7.  A warm-up electrical cable pulls out on release.


Destructor: The Destructor M8 mounted under and tot he starboard of the control compartment is actuated, on impact, by the Fuze M121.









Similar Project

JB-2 (A.A.F.) or "Loon" (BuAer) - A Modification of the German V-1

Overall length: 21 feet 1.1 inches
Span: 17 feet 8.1 inches
Total weight: 5,025 pounds

Warhead (T9):
Weight: 2,100 pounds
Filling: 1,875 pound of Tritonal


General: The JB-2 and "Loon" are copies of the German V-1, with modifications.  As far as the ordnance components are concerned, the Army and Navy modifications are the same.


Warhead: The warhead is an aluminum-encased charge of Tritonal.  The case is 3/8-inch thick and is bolted to the fuselage abaft the nose piece by four lugs.

Destructor (T15): At the appropriate distance from the target, as determined by the Veeder Root Counter, an electrical contact is closed, which sets off the electric blasting caps int he Destructor T15, igniting the small charge and blasting apart the two junctions in the wing spar.  The spar breaks; the wings come off; and the missile is forced into the dive toward its target.

Previously, the missile was put into its dive by the action of the Spoiler Actuators T1.  These were small steel bullet-like cups filled with black powder and an electric squib.  When activated by the Veeder Root Counter, they were fired down two vertical tubes in the tail section, releasing a spring-loaded knife arm which cut the rubber hoses from the servo motors to the controls; and, at the same time, the spring pulled the elevators down, putting the bomb into its dive.


Remarks: This missile uses liquid oxygen as fuel, this oxygen being highly explosive.

Next Time: ???