| Me 163 Komet | |
|---|---|
| Me 163B-1a at the National Museum of Flight in Scotland | |
| Role | Interceptor |
| Manufacturer | Messerschmitt |
| First flight | Me 163 A V4 in 1 September 1941 |
| Introduction | 1944 |
| Primary user | Luftwaffe |
| Number built | ~370[1] |
The Messerschmitt Me 163 Komet,[N 1] designed by Alexander Lippisch, was a German rocket-powered fighter aircraft. It is the only rocket-powered fighter aircraft ever to have been operational. Its design was revolutionary, and the Me 163 was capable of performance unrivaled at the time. Messerschmitt test pilot Rudy Opitz in 1944 reached 1,123 km/h (698 mph). Over 300 aircraft were built,[2] however the Komet proved ineffective as a fighter, having been responsible for the destruction of only about nine Allied aircraft[2] (16 air victories for 10 losses, according to other sources).[3]
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Work on the design started under the aegis of the Deutsche Forschungsanstalt für Segelflug (DFS)—the German Institute for the Study of sailplane flight. Their first design was a conversion of the earlier Lippisch Delta IV known as the DFS 39 and used purely as a glider testbed of the airframe.
A larger follow-on version with a small propeller engine started as the DFS 194. This version used wingtip-mounted rudders, which Lippisch felt would cause problems at high speed. He later redesigned them to be mounted on a conventional vertical stabilizer at the rear of the aircraft. The design included a number of features from its glider heritage, notably a skid used for landings, which could be retracted into the aircraft's keel in flight. For takeoff, a pair of wheels, each mounted onto the ends of a specially designed cross-axle, together comprising a takeoff "dolly" mounted under the landing skid, were needed due to the weight of the fuel, but these were released shortly after takeoff. It was planned to move to the Walter R-1-203 cold engine of 400 kg (880 lb) thrust when available.
Heinkel had also been working with Hellmuth Walter on his rocket engines, mounting them in the He 112 for testing, and later in the first purpose-designed rocket aircraft, the He 176. Heinkel had also been selected to produce the fuselage for the DFS 194 when it entered production, as it was felt that the highly volatile fuel would be too dangerous in a wooden fuselage, with which it could react. Work continued under the code name Projekt X.[4]
However the division of work between DFS and Heinkel led to problems, notably that DFS seemed incapable of building even a prototype fuselage. Lippisch eventually requested to leave DFS and join Messerschmitt instead. On 2 January 1939, he moved along with his team and the partially completed DFS 194 to the Messerschmitt works at Augsburg.
The delays caused by this move allowed the engine development to "catch up". Once at Messerschmitt, the decision was made to skip over the propeller-powered version and move directly to rocket power. The airframe was completed in Augsburg and shipped to Peenemünde West[N 2] in early 1940 to receive its engine. Although the engine proved to be extremely unreliable, the aircraft had excellent performance, reaching a speed of 342 mph (550 km/h) in one test.
Production of a prototype series started in early 1941, known as the Me 163. Secrecy was such that the number, 163, was actually that of the earlier, pre-July 1938 Messerschmitt Bf 163 project to produce a small two-passenger light plane, which had competed against the Fieseler Fi 156 Storch for a production contract. It was thought that intelligence services would conclude any reference to the number "163" would be for that earlier design. The Me 163 A V4 was shipped to Peenemünde to receive the HWK RII-203 engine on May 1941. By 2 October 1941, the Me 163 A V4, bearing the radio call sign letters, or Stammkennzeichen, "KE+SW", set a new world speed record of 1,004.5 km/h (624.2 mph), piloted by Heini Dittmar.[5][6] This would not be officially approached until the postwar period by the new jet fighters of the British and U.S., and was not surpassed until the American Douglas Skystreak turbojet-powered research aircraft did so on 20 August 1947. Five prototype Me 163 Anton A-series experimental V-aircraft were built, adding to the original DFS 194 (V1),[7] followed by eight pre-production examples designated as "Me 163 A-0".
During testing, the jettisonable main landing gear arrangement was a serious problem. The landing gear caused many aircraft to be damaged at takeoff, when the wheels rebounded and crashed into the aircraft. Malfunctioning hydraulic dampers in the skid could cause back injuries to the pilot when landing, as the aircraft lacked steering or braking control during landing, and was unable to avoid obstacles. Once on the ground, the aircraft had to be retrieved by a Scheuch-Schlepper converted small agricultural vehicle, towing a special retrieval trailer that rolled on a pair of short continuous-track setups (one per side), with twin trailing lifting arms, that lifted the stationary aircraft off the ground, from under each wing. The three-wheeled Scheuch-Schlepper[8] tractor used for the task was originally meant for farm use, but such a vehicle with a specialized trailer was required as the Komet was unpowered and lacked main wheels at this point.
During flight testing, the superior gliding capability of the Komet proved detrimental to safe landing. The aircraft would rise back into the air with the slightest updraft. Since the approach was unpowered, there was no opportunity to make another landing pass. For production models, a set of landing flaps allowed somewhat more-controlled landings. This issue remained a problem throughout the program.
Nevertheless, the overall performance was tremendous, and plans were made to put Me 163 squadrons all over Germany in 40-kilometre rings (25 mi). Development of an operational version was given the highest priority.
Meanwhile, Walter had started work on the newer HWK 109-509 hot engine, which added a true fuel of hydrazine hydrate and methanol, designated C-Stoff, that burned with the oxygen-rich exhaust from the T-Stoff, used as the oxidizer, for added thrust (see: List of Stoffs). This resulted in the significantly modified Me 163 B of late 1941. Due to the Reichsluftfahrtministerium (RLM) requirement that it should be possible to throttle the engine, the original power plant grew complicated and lost reliability. The new fuel proved an unfortunate choice as well, since hydrazine hydrate was also used in the launcher of the V-1 "Doodlebug" flying bomb and was in short supply throughout the 1943–45 period.
The fuel system was particularly troublesome, as leaks experienced during hard landings easily caused fires and explosions. Metal fuel lines and fittings, which failed in unpredictable ways, were used as this was the best technology available. Both fuel and oxidizer were toxic and required extreme care when loading in the aircraft, yet there were occasions when Komets exploded on the tarmac from the propellants' hypergolic nature. The corrosive nature of the liquids, especially for the T-Stoff oxidizer, required special protective gear for the pilots.
Two prototypes were followed by 30 Me 163B-0 aircraft armed with two 20 mm MG 151/20 cannon and some 400 Me 163B-1 planes armed with two 30 mm (1.18-inch) MK 108 cannons, but which were otherwise similar to the B-0. Occasional references to B-1a or Ba-1 subtypes are found in the literature on the aircraft, but the meanings of these designations are somewhat unclear. Early in the war, when German aircraft firms created versions of their aircraft for export purposes, the a was added to export (ausland) variants (B-1a) or to foreign-built variants (Ba-1) but for the Me 163, there were neither export nor a foreign-built version. Later in the war, the "a" and successive letters were used for aircraft using different engine types: as Me 262A-1a with Jumo engines, A-1b with BMW engines. As the Me 163 was planned with an alternative BMW P3330A rocket engine, it is quite safe to assume the "a" was used for this purpose on early examples. Only one Me 163, the V10, was tested with the BMW engine, so this designation suffix was soon dropped. The Me 163 B-1a did not have any wingtip "washout" built into it, and as a result, it had a much higher critical Mach number than the Me 163 B-1.[9]
The Me 163B had very docile landing characteristics, mostly due to its integrated leading edge slots, located directly forward of the elevon control surfaces, and just behind and at the same angle as the wing's leading edge. It would neither stall nor spin. One could fly the Komet with the stick full back, and have it in a turn and then use the rudder to take it out of the turn, and not fear it snapping into a spin. It would also slip well. Because it was derived from a glider, it had excellent gliding qualities, and had tendency to continue flying above the ground due to ground effect. On the other hand, making a too close turn from base onto final, the sink rate would increase, and one could quickly lose altitude and come in short. Another main difference from a propeller-driven aircraft is that there was no slipstream over the rudder. On takeoff, one had to attain the speed at which the aerodynamic controls become effective—about 129 km/h (80 mph)—and that was always a critical factor. Pilots used to flying propeller driven aircraft had to be careful the control stick was not somewhere in the corner when the control surfaces began working. These, like many other specific Me 163 problems, would be resolved by specific training.
The performance of the Me 163 far exceeded that of contemporary piston engine fighters. At a speed of over 320 km/h (200 mph) the aircraft would take off, in a "sharp start" from the ground, from its two-wheeled dolly. The aircraft would be kept at low altitude until the best climbing speed of around 676 km/h (420 mph) was reached, at which point it would jettison the dolly, pull up into a 70° angle of climb, and rapidly climb to a bomber's altitude. It could go higher if required, reaching 12,000 m (39,000 ft) in an unheard-of three minutes. Once there, it would level off and quickly accelerate to speeds around 880 km/h (550 mph) or faster, which no Allied fighter could match. The usable Mach number was similar to the Me 262, but because of the high thrust to drag ratio, it was much easier for the pilot to lose track of the onset of severe compressibility and loss of control. A Mach warning system was installed as a result. The aircraft was remarkably agile and docile to fly at high speed. According to Rudolf Opitz, chief test pilot of the Me 163, it could "fly circles around any other fighter of its time".
By this point, Messerschmitt was completely overloaded with production of the Bf 109 and attempts to bring the Me 210 into service. Production in a dispersed network was handed over to Klemm, but quality control problems were such that the work was later given to Junkers, who was, at that time, underworked. As with many German designs of World War II's later years, parts of the airframe (especially wings) were made of wood by furniture manufacturers.
The older Me 163A and first Me 163B prototypes were used for training. It was planned to introduce the Me 163 S, which removed the rocket engine and tank capacity and placed a second seat for the instructor above and behind the pilot, with its own canopy. The 163 S would be used for glider landing training, which as explained above, was essential to operate the Me 163. It appears the 163 Ss were converted from the earlier Me 163B series prototypes.
In service, the Me 163 turned out to be difficult to use against enemy aircraft. Its tremendous speed and climb rate meant a target was reached and passed in a matter of seconds. Although the Me 163 was a stable gun platform, it required excellent marksmanship to bring down an enemy bomber. The Komet was equipped with two 30 mm (1.18 inch) MK 108 cannons which had a relatively low muzzle velocity of 540 meters per second (1,207 mph, 1,944 km/h), with the characteristic ballistic drop of such a weapon. The drop meant they were only accurate at short distance, and that it was almost impossible to hit a slow-moving bomber when the Komet was traveling very fast. Four or five hits were typically needed to take down a B-17.
A number of innovative solutions were implemented to ensure kills by less experienced pilots. The most promising was a unique weapon called the Sondergerät 500 Jägerfaust. This consisted of a series of single-shot, short-barreled 50 mm (2-inch) guns pointing upwards. Five were mounted in the wing roots on each side of the aircraft. The trigger was tied to a photocell in the upper surface of the aircraft, and when the Komet flew under the bomber, the resulting change in brightness caused by the underside of the aircraft could cause the rounds to be fired. As each shell shot upwards, the disposable gun barrel that fired it was ejected downwards, thus making the weapon recoilless. It appears that this weapon was used in combat only once, resulting in the destruction of a Halifax bomber,[10] although other sources say it was a Boeing B-17.[11][12]
The biggest concern about the design was the short flight time, which never met the projections made by Walter. With only seven and a half minutes of powered flight, the fighter truly was a dedicated point defense interceptor. To improve this, the Walter firm began developing two more advanced versions of the 509A rocket engine, the 509B and C, each with two separate combustion chambers of differing sizes, oriented one above the other, with greater efficiency.[13]
The upper chamber, intended as the motor's primary power output, was larger, and supported by the "thrust tube" exactly as the 509A motor's single chamber had been. It was tuned for "high power" for takeoff and climb. The smaller-volume, lower chamber, with approximately 400 kg (880 lb) of thrust at its top performance level, was intended for more efficient, lower-power cruise flight. This HWK 109–509 C would improve endurance by as much as 50%. Two 163 Bs, models V6 and V18, were experimentally fitted with the new twin-chamber engine, a retractable tailwheel, and tested in spring 1944.[13]
The main combustion chamber of the 509C engine occupied the same location as the A-series' engine did, with the lower "cruise chamber" occupying a space just below it and above the retractable tailwheel. On 6 July 1944, the Me 163 B V18 (VA+SP) set a new world speed record of 1,130 km/h (702 mph), piloted by Heini Dittmar, and landed with almost all of the vertical rudder surface broken away from flutter.[5][14] This record was not broken in terms of absolute speed until 6 November 1947 by Chuck Yeager in a flight that was part of the Bell X-1 test program, with a 1,434 km/h (891 mph), or Mach 1.35 supersonic speed, recorded at an altitude of nearly 14,820 m (48,620 ft). [N 3].
However, the X-1 never exceeded Dittmar's speed from a normal runway liftoff. Heini Dittmar had reached the 1,130 km/h (702 mph) performance, after a normal "sharp start" ground takeoff, without an air drop from a mother ship. Neville Duke exceeded Heini Dittmars record mark in 31 August 1953, with the Hawker Hunter F Mk3 at a speed of 1,171 km/h (728 mph), after a normal ground start.[15][N 4]
Aircraft of the configuration the Me 163 used were found to have serious stability problems when entering transonic flight, like the similarly configured, and turbojet powered, Northrop X-4 Bantam and de Havilland DH 108, which made the V18's record with the Walter 509C "cruiser" rocket more remarkable.
Waldemar Voigt of Messerschmitt's Oberammergau project and development offices started a redesign of the 163 to incorporate the new engine, as well as fix other problems. The resulting Me 163 C design featured a larger wing through the addition of an insert at the wing root, an extended fuselage with extra tank capacity through the addition of a "plug" insert behind the wing, and a new pressurized cockpit topped with a bubble canopy for improved visibility. The additional tank capacity and cockpit pressurization allowed the maximum altitude to increase to 15,850 m (52,000 ft), as well as improving powered time to about twelve minutes, almost doubling combat time (from about five minutes to nine). Three Me 163C-1a prototypes were planned, but it appears only one was flown, without its intended engine.[16]
By this time the project was moved to Junkers. There, a new design effort under the direction of Heinrich Hertel at Dessau attempted to improve the Komet. The Hertel team had to compete with the Lippisch team and their Me 163C. Hertel investigated the Me 163 and found it was not well suited for mass production and not optimized as a fighter aircraft, with the most glaring deficiency being the lack of retractable landing gear. For this, the Me 163V-18 was equipped with a non-retractable tricycle landing gear. (This prototype was also called the "Me 163DV-1", later it was assigned to the Ju 248 program.[17][18])
The resulting Junkers Ju 248 used a three-section fuselage to ease construction. The V1 prototype was completed for testing in August 1944, and was glider tested behind a Junkers Ju 188. Some sources state that the Walter 109–509 C engine was fitted in September, but it was probably never tested under this power. At this point the RLM re-assigned the project to Messerschmitt, where it became the Messerschmitt Me 263. This appears to have been a formality only, with Junkers continuing the work and planning production.[19]
By the time the design was ready to go into production, the plant where it was to be built was overrun by Soviet forces. While it did not reach operational status, the work was briefly continued by the Soviet Mikoyan-Gurevich (MiG) design bureau as the Mikoyan-Gurevich I-270.[20]
Active combat operations began in May 1944, although on a small scale. As expected, the aircraft was extremely fast; and for a time, the Allied fighters were at a complete loss as what to do about it. Singly or in pairs, the Komets attacked, often faster than the opposing fighters could dive in an attempt to intercept them. A typical Me 163 tactic was to zoom through the bomber formations at 9,000 m (30,000 ft), rise up to an altitude of 10,700–12,000 m (35,100–39,000 ft), then dive through the formation again. This approach afforded the pilot two brief chances to fire a few rounds from his cannons before gliding back to his airfield. The pilots reported that it was possible to make four passes on a bomber, but only if it was flying alone.[21]
As the cockpit was unpressurized, the operational ceiling was limited by what the pilot could endure for several minutes while breathing oxygen from a mask, without losing consciousness. Pilots underwent altitude-chamber training to harden them against the rigors of operating in the thin air of the stratosphere without a pressure suit. Special low-fiber diets were prepared for pilots, as gas in the gastrointestinal tract would expand rapidly during ascent.
More than three years passed before Major Wolfgang Späte could form the first Me 163 combat wing, (Jagdgeschwader 400 (JG 400) ), in Brandis near Leipzig, which followed the establishment of the Erprobungskommando 16 Me 163B-dedicated test and evaluation unit at Peenemunde-West eleven months earlier. JG 400's purpose was to provide additional protection for the Leuna synthetic gasoline works which were raided particularly heavily and frequently at the end of 1944. A further group was stationed at Stargard near Stettin to protect the large synthetic plant at Pölitz (today Police, Poland). Further defensive units of rocket fighters were planned for Berlin, the Ruhr and the German Bight.[22]
The first actions involving the Me 163 occurred at the end of July, when two USAAF B-17 Flying Fortress were attacked without confirmed kills. Combat operations continued from May 1944 to spring 1945. During this time, there were nine confirmed kills with 14 Me 163s lost. Feldwebel Siegfried Schubert was the most successful pilot, with three bombers to his credit.[23]
Allied fighter pilots soon noted the short duration of the powered flight. They would wait, and when the engine died they would pounce on the unpowered Komet. However, the Komet was extremely manoeuvrable and could pull out of a turn much later than any Allied fighter. Another Allied method was to attack the fields the Komets operated from, and strafed them after the Me 163s landed.[24] Establishing a defensive perimeter with anti-aircraft guns ensured that Allied fighters avoided these bases. At the end of 1944, 91 aircraft had been delivered to JG 400 but a continuous lack of fuel had kept most of them grounded. It was clear that the original plan for a huge network of Me 163 bases was never going to happen. Up to that point, JG 400 had lost merely six aircraft due to the enemy actions. Nine were lost to other causes, remarkably low for such a revolutionary and technically advanced aircraft. In those last days of the Third Reich the Me 163 was given up in favour of the more successful and threatening Me 262. In May 1945, Me 163 operations were stopped, the JG 400 disbanded, and many of their pilots sent to fly Me 262s.[21]
In any operational sense, the Komet was a failure. Although they shot down 16 aircraft, mainly expensive four-engined bombers, that did not warrant the efforts put into the project. With the projected Me 263, things could have turned out differently, but due to fuel shortages late in the war, few went into combat, and it took an experienced pilot with excellent shooting skills to achieve "kills" with the Me 163.
The Komet also spawned later weapons like the Bachem Ba 349 Natter and Convair XF-92. Ultimately, the point defense role that the Me 163 played would be taken over by the surface-to-air missile (SAM), Messerschmitt's own example being the Enzian. The airframe designer, Alexander Martin Lippisch went on to design delta-winged supersonic aircraft for the Convair Corporation.
Capt. Eric Brown RN, Chief Naval Test Pilot and commanding officer of the Captured Enemy Aircraft Flight, who tested the Me 163 at the Royal Aircraft Establishment (RAE) at Farnborough, said, "The Me 163 was an aeroplane that you could not afford to just step into the aircraft and say 'You know, I’m going to fly it to the limit.' You had very much to familiarise with yourself with it because it was state-of-the-art and the technology used.".[25]
Acting unofficially, after a spate of accidents involving Allied personnel flying captured German aircraft resulted in official disapproval of such flights, Brown was determined to fly a powered Komet, and on around 17 May 1945, he flew an Me 163B at Husum with the help of a co-operative German ground crew, after initial towed flights in an Me 163A to familiarise himself with the handling. The day before the flight, Brown and his ground crew had performed an engine run on the chosen Me 163B to ensure that everything was running correctly, the German crew being apprehensive should an accident befall Brown, until being given a disclaimer signed by him to the effect that they were acting under his orders. On the take-off the next day, after dropping the take-off trolley and retracting the skid, Brown later described the resultant climb as "like being in charge of a runaway train", the aircraft reaching 32,000 ft in two and a three-quarter minutes. During the flight, while practising attacking passes at an imaginary bomber, he was surprised at how well the Komet accelerated in the dive with the engine shut down. When the flight was over Brown had no problems on the approach to the airfield apart from the rather restricted view from the cockpit due to the flat angle of glide, the aircraft touching down at 125 mph. Once down safely, Brown and his much-relieved ground crew celebrated with a drink.[26]
Apart from Brown's unauthorised flight, the British never tested the Me 163 under power themselves, due to the danger of its hypergolic propellants—it was only flown unpowered, Brown himself piloting RAE's Komet VF241 on a number of occasions, the rocket motor being replaced with test instrumentation.
It has been claimed that at least 29 Komets were shipped out of Germany after the war and that of those at least 10 have been known to survive the war[27] to be put on display in museums around the world. Most of the 10 surviving Me 163s were part of JG 400, and were captured by the British at Husum, the squadron's base at the time of Germany's surrender in 1945. According to the RAF museum, 48 aircraft were captured intact and 24 were shipped to the United Kingdom for evaluation, although only one, VF241, was test-flown (unpowered).[28]
Of the 21 aircraft that were captured by the British, at least three have survived until today. They were assigned the British serial numbers AM200 to AM220.[29]
As part of their alliance, Germany provided the Japanese Empire with plans and an example of the Me 163.[32] One of the two submarines carrying Me 163 parts did not arrive in Japan, so at the time, the Japanese lacked a few important parts, including the turbopump which they could not make themselves. The Japanese Me 163 crashed on its first flight and was completely destroyed.[33] The Japanese versions were designed as trainers, fighters, and interceptors. Differences between the versions were fairly minor. The Mitsubishi Ki-200 Shusui ("Shu" means "autumn", "sui" means "water" in Japanese) was the equivalent of the 163 B, armed with two 30 mm (1.18 in) Ho 155-II cannon. The Navy version, the Mitsubishi J8M1 Shusui, simply replaced the Ho 155 cannon with the Navy's 30 mm (1.18 in) Type 5.
Mitsubishi also planned on producing a version of the 163 C for the Navy, known as the J8M2 Shusui Model 21. A version of the 163 D/263 was known as the J8M3 Shusui for the Navy with the Type 5 cannon, and a Ki-202 Shusui-kai ("kai" means "modified" in Japanese) with the Ho 155-II for the Army.
Trainers were planned, roughly the equivalent of the Me 163 A-0/S. These were known as the Yokoi Ku-13 Akigusa ("Aki" means also "autumn" and "gusa (kusa)" means "grass" in Japanese) or Ki-200 Syusui Rocket Interceptor practice glider ("Syusui" with "y").
Other trainer variants included:
A flying reproduction Me 163 was constructed between 1994 and 1996 by Joseph Kurtz, a former Luftwaffe pilot who trained to fly Me 163s, but who never flew in combat. He subsequently sold the aircraft to EADS. The reproduction is an unpowered glider whose shape closely matches that of an Me 163, although its weight and internal construction differ considerably. Reportedly, it has excellent flying characteristics.[34]
XCOR Aerospace, an aerospace and rocketry company, proposed a rocket-powered airworthy reproduction, the Komet II. Although outwardly the same as a wartime aircraft, the design would have differed considerably for safety reasons. It would have been partially constructed with composite materials, powered by one of XCOR's own simpler and safer, pressure fed, liquid oxygen/alcohol engines, and retractable undercarriage would have been used instead of a takeoff dolly and landing skid.[35] The project is no longer discussed on the company's website, and it appears work has ceased on this project.
Several static reproductions of the aircraft are exhibited in museums.
General characteristics
Performance
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