The eighteen pot injector head.
This is the first image blog from Alexsander Savochkin in what we hope will become an expanding resource for those wishing to find out more about the design and construction of the A4/V2 missile. The precise 3D CAD model imagery is based exclusively on original drawings produced in Germany from 1940 to 1945. When enough material has been uploaded we will create a fixed menu item called ‘Anatomy of the V2‘ where we hope to be able to offer coverage of the entire missile in detailed 3D models like the ones shown here – Robert J. Dalby, editor in chief, V2 Rocket History.com
Click the above video to see an animation of the diffuser cup inner core (the animation may take a few seconds to show at maximum resolution).
The image gallery below has all the above pictures in higher resolution, some with additional text, as well as additional pictures not included in this post.
Each burner cup of the V2 rocket engine injector system has forty-four brass inserts, but each cup also has twenty-four 2mm diameter plain holes, 30 deg apart, drilled into the cup's central wall. To mimic this for testing purposes, we created a brass insert that has a base with just a 2mm central hole. The base is sized to be consistent with the 4 to 5mm cup wall. V2RH image
Sample set of 3303D type fuel injector inserts that were found in Peenemünde in part of a group that were bunched together in a space about 300mm in diameter with the remains of packaging. They appear to be manufacturing samples and and some have been graded with numbers 1,2,3, as well as with red and white paint to show the burner cup echelon position (C or D). Five different manufacturers are represented in this group. V2RH collection image
The injector head fragment shown here, is from an 4B 1000 kg thrust engine that was developed at Kummersdorf in 1938/39 by Dr Walter Thiel's combustion research group. The fragment, clearly the remains of an explosion, was actually found in a scrap pile in Peenemüde but the engine was probably tested (and destroyed) at the Kummersdorf army testing station. V2RH collection image.
Photo shows a small section of the burner cup with row A (2131E) fuel injector inserts with three row B drilled holes below. The two undamaged inserts carry the armament code 'csl'. The relic was found near a workshop in the Development works Pennemünde. Slag from the cutting flame and damage to the inserts at both ends of the relic would indicate that the section was cut from a steel burner cup using a gas cutter (fuel and oxygen) for purposes unknown. V2RH collection image
V2 Fuel Injector insert: part code 2131E from injector pot echelon A (nearest to LOX spray head). The push-together two part construction of the insert is shown here. The two parts were pushed together in a specially shaped tool set that compressed the thin skirt on the female part into a recess cut into the male part. The failure test for this component required that the mated parts resist a separating force of 300kg. The two part design was dictated by the small size of the 2mm exit orifice and the funnel shaped introduction to the exit orifice. In the case of the other three standard inserts, the large 6mm exit orifice allowed a sub 6mm milling cutter, with a thin support shaft and a top chamfer, to be used in such a way that the area below the exit orifice could be undercut to create an injector cavity with a diameter larger than the 6mm entry point.
V2 fuel injector inserts 3303D, 3304D, and 3305D for injector pot echelons D and E. Photo shows swirl inlet aperture size and position.The total number of each insert type is shown, each of the 18 pots carried a total of 44 inserts. An additional 24 feed holes were drilled into the burner cup, occupying two rows B and C having 12 holes each. V2RH image
Wreckage of V2 combustion chamber with a tangle of connection pipes laying in a garden in Southern England - winter 1944. The censor has obscured the background to avoid providing the enemy with useful information. The injection head shows two connected lock 'spanners' securing the nuts of oxygen inlet pipes. Prior to impact all 18 of the LOX pipe input nuts would have been secured by these lightweight pressed steel 'spanners'.
Picture shows parts of V2 missile fin structure laying on open ground near area between admin offices and F1 (near Admin. block railway platform, see map).
This picture shows a small debris field of steel fragments from the V2 missile 130m South-East of F1, and just 20m to the North East of the foundations of a small heat distribution building. Various body and frame parts can be seen and in the middle foreground a 350mm segment of curved missile body ring is visible. These parts have almost certainly been dug up and exposed by the action of metal detectorists. The metal fragments have been abandoned by their finders as they are perceived to have no financial value and hence are not worth removing from the site.
This picture shows a close up detail of parts in a small debris field of steel fragments from the V2 missile 130m South-East of F1, and just 20m to the North East of the foundations of a small heat distribution building. Various body and frame parts can be seen and in the upper left and two segments of curved missile body ring are visible. See previous.
V2 missile parts in F1 prisoner turn-out or 'free movement' area. The location referred to is a large triangular shaped area situated on the South-East side of the pre-propuction hall Fertigungshalle Eins (F1). The area was fenced off with a high barbed wire fence (a portion of which was electrified) with guard towers every 60 metres.
The photo shows a Lichtstrahl empfänger (In English: Light-beam receiver) environmental protection case, originally one of a group of 40 or so we first found in 2010 abandon in an area adjacent to the train platform for the administration block. On subsequent visits this number has declined to just ten or so, mostly very decayed examples. The environmental casing was vital to the Lorentz Light-Beam equipment on-board the V2 missile as the critical radio frequency would otherwise drift with the large change in temperature as the missile climbed into the stratosphere. The case was thickly insulated with rock wool or fibre-glass strands and designed to help maintain a stable temperature - indeed, the same temperature as the radio equipment was when at ground level when calibration and adjustment was completed before launch. The F1 pre-production hall is located about 200m North-West of the point where this photo was taken. Scroll down to see map below (click map and switch to 'satellite view' for clearer indication of location).
Photo shows cast aluminium thrust ring with electro-hydraulic servos in position. Note different crank lever shapes (pale green arm on servo) for fins 1/3 and 2/4 This excellent restoration is the work of Horst Beck. Photo copyright: The Horst Beck Collection
Photo shows rare surviving complete set of 8 lead acid battery cells from one of the V2 rocket's 32 volt (100 amp) lead acid batteries. Two sets of batteries like this were used to provide the direct current (DC) voltage used aboard the V2 missile to power the DC to 3-phase alternating current (AC) generators, that in turn, powered the gyroscopes, electro-hydraulic servos, trim motors and other vital guidance and control devices. Photo copyright: The Horst Beck Collection
Photo shows a unique display at the Horst Beck Collection (HBC). Over many years Mr Horst Beck has painstakingly acquired and restored many A4-V2 missile parts - and in some cases, reassembled them into complete sub-assemblies. Shown here is part of the collection's hydraulic servos and trim motor parts display. In the foreground we see four hydraulic servos, and behind them their A frame mounting 'chairs'. The top shelf, from left to right, shows a servo with motor removed (and placed on its right). In the middle, two trim motors and chain sprocket gear-boxes for the aerodynamic trim surfaces on the trailing edge tips of fins 2 and 4. Next the pale green crank levers, the first longer one is for the hydraulic servo that controls the jet vanes and trimmers on fins 1 and 3. The shorter version minus the top horn, is used on the servos for fins 2 and 4. The last, silver coloured item,os a servo stabiliser (all the servos shown have one already fitted). Photo copyright: The Horst Beck Collection
Photo shows restored air-rudder and fin detail. The grey painted barrel-strainers are both adjusted independently to reduce slack in the drive chain and avoid introducing a deflection bias in the air rudder. The 1.9kg counterbalance weight normally located at the top of the trim fin (or air rudder) is missing in this presentation. This excellent restoration is the work of Horst Beck. Photo copyright: The Horst Beck Collection
Photo shows partially restored air-rudder and fin detail. The image on the left shows the relationship of the trim motor to the air rudder drive shaft on fins 2 and 4. A chain similar in gauge to the type used on a push-bike and yet, at the other end of the shaft, the chain transmitting the torque of the trim motor to the air-rudder drive sprocket has a heavy gauge chain similar to that found on a 1000CC motor-cycle! This excellent restoration is the work of Horst Beck. Photo copyright: The Horst Beck Collection
Photo shows four restored graphite jet vane support blocks and bearing housings. The round plates we can see here act as heat sinks and allow heat to radiate away from the support block and bearing to help prevent expansion due to relatively rapid and uneven temperature distribution accumulation. The graphite vanes were quite brittle and cracking caused by rapid and uneven expansion could cause the vane to disintegrate. The area around the graphite vanes was exposed to the accumulation of heat not merely as a result of duration of the motor burn time but temperature was also increased at higher rates as the jet plume expanded with the decreasing atmospheric pressure as the missile gained altitude. This excellent restoration is the work of Horst Beck. Photo copyright: The Horst Beck Collection
Photo shows rare surviving 1.2 volt cell from the V2 missile's 50 volt command or signalling battery used in its gyro guidance system (note, the terminal connection on the left is missing from this exhibit, it would be identical to the one on the right). This wet nickel-cadmium battery cell was combined in pairs to a total set of 21 providing a 50.4 voltage at 300mA. The cells were contained in a wooden box that was held on a rack in equipment bay III. Its function was to provide the direct current (DC) signalling voltage that communicated the moment to moment resistance of the gyroscope's potentiometers to the analog guidance computer (Mischgerät = Mixer-device or control amplifier) aboard the V2 missile. It was critical that the signalling voltage was maintained between 48 and 50.4 volts. Photo copyright: The Horst Beck Collection
Wreckage of hydraulic servo from fin 2 or 4 of V2 missile that fell on a farm in Essex in March 1945. The motor has been removed and we can see details of the oil gear pump and valve control gear. The 3 position electromagnetic relay switch is visible at the 7 to 8 o'clock position within the open aperture. The push rod that connects the relay to the gear pump valves is also visible as a short brown coloured rod with a fine wire connector at each end, running in towards the gear-valves from the 9 o'clock position. The point that provides electrical current for the motor (which runs all the time and in one direction only) can be seen at the three o'clock position. The black housing has two sets of brass tongues that receive the matching brass spades mounted on the base of the motor for power input. The motor drive shaft has a female square socket coupling to connect the motor to the middle drive gear of the gear pump. A small portion of the square drive shaft of the central gear can just be seen in the photo - in the centre of the valve control block.
25-Ton aluminium injector head showing mpe armament code for the Heimat-Artillerie-Park 11 (HAP11) Karlshagen Werk Nord.
Part of the 'Standard' series A aluminium head from 1941 to early 1942. Showing the position of standard type LOX injector. The brass fuel injector inserts type and position pattern on the relic seem to be of the standard type with the row of 3 inlet aperture type inserts positioned furthest from the LOX injector. Photo courtesy Horst Beck Collection
Relic of A4 25-ton 1940/41 aluminium injector head basket (or pre-chamber) showing 68 copper alloy inserts in 5 rows. The standard configuration would later become 44 inserts in 3 rows 25 2mm diameter drilled holes in two rows situated at row 3 and 4 (counting from nearest the camera). Photo courtesy Host Beck Collection
Injector head relic from February 1945 showing injector insert type and pattern. Photo www.v2rockethistory.com
Flown V2 thrust chamber relic from February 1945. Badly damaged from impact, this head shows 4 intact LOX input pipe connections as well as exposed fuel injector inserts positioned in the inner wall of the injector pots. The inner and outer walls of the head are also conveniently exposed on this exhibit. Photo www.v2rockethistory.com
Hydraulic gear pump with close up detail showing ceramic heater element insulators with flat, possibly nichome, metal strip element threaded through them. This oil heating system was designed to maintain a specific viscosity of the oil regardless of environmental temperature, to better maintain oil flow rates and thus pump efficiency. The heating system is found only rarely on surviving relics.
This collection of parts were all found in vicinity of the Nordhausen manufacturing facility. parts include servo crankcase caps -top left, electro-magnetic switch installation plate - middle top, crank bearing covers - top right, gear pump blocks with base - centre, and crank-shaft, piston rod, and hydraulic piston - btm left. The deep recess on the piston circumference is for a rubber seal and is an interesting variation in ring seal design (at least 4 variations of piston design were employed, with three designs flown on combat missiles). A valve tilt seat is visible a little to the right of the piston. A broken servo mount stabiliser is shown - middle right. The cast piston rod, top right, has not been drilled and milled - the part is 'raw' as supplied by the manufacturer before machining has been completed. Normally the manufacturer's details are machined off the metalwork - but not in this rare case. The three letter code gfa is clearly visible on the part and stands for the firm of Otto Fuchs Metallwerke.
Gear pump showing flow adjusters (two slot head screws nearest bottom of picture) and ceramic heater elements situated at each end of the block. The square drive shaft coupler (corroded but still identifiable) has been highlighted in red paint. The open holes either side are the main control valve guides. The copper spring strips visible on each oil flow adjuster provide locking and tactile feed-back for the adjusting process. This relic was recovered from Usedom island.
V2 Rocket History Museum Relic: This cutaway presentation shows one of the V2's 18 combined fuel and liquid oxygen (LOX) injector 'pots'. The LOX injector transit cap is also shown. The pot shown here is sometimes incorrectly referred to as a pre-burner or pre chamber - a mixer or diffuser pot probably describes its role more accurately.
This relic from the V2 Rocket History collection shows a cutaway presentation of one of the V2's 18 combined fuel and liquid oxygen (LOX) injector 'pots'. The LOX injector transit cap is also shown fitted over the LOX injector.
V2 engine part from a missile fired from Walcheren, Serooskerke, Vrederust, by battery no 444, at around 7am on September 17th 1944. The missile impacted East Ham with a direct hit on houses. Killing 6 people with 15 seriously injured. Much of the rocket debris was taken to the East Ham police station for examination by the military authorities. Information porovided by www.v2rocket.com.
Examination of V2 missile thrust chamber. Sections of two of the large bore aluminium alcohol inlet manifold feed pipes and two thin steel veil colling supply pipes are still attached. The distinctive heat expansion relief loop can be seen on one of the pipes.
Image shows interior of production series (combat relic) V2 missile propellent injector pre-mixer pots. Three post in the picture are intact, others seem in the picture have been destroyed in the impact. This engine part was recovered from a combat impact East of London. Impact date: February 1945
Recovered from Great Warley impact: February 1945. This chamber has a production use order number of 33 painted crudely on topmost segment. This number, to indicate rank in batch, was added shortly after manufacture to ensure the chamber was selected by the missile assembly crews in the correct order; that is on a newest-last basis to make sure that the oldest chambers were employed in missile construction operations first.
Two Askania (designed) hydraulic gear pumps - the examples shown here have two ceramic insulators with with Nichrome wire type heating elements. The heaters are located at each end of the pump on the long axis. The pump on the right still has its power supply wires attached and was easily repaired and restored to full function in our workshop.This type of pump (with heaters) seem to be rare among the debris of European combat impact sites but fairly common in debris collections emanating from research flights in Peenemünde and parts of Poland. An explanation maybe that the oil could be warmed up sufficiently simply by starting all four hydraulic gear pumps sooner in the pre-launch sequence. The only downside being that the already noisey missile would be making yet more noise in the risky period leading up to launch.