Monthly Archives: August 2020

Fighter

Messerschmitt Me 263 “Scholle” (Plaice), (Huma)

Gallery

TYPE: Fighter interceptor

ACCOMMODATION: Pilot only

POWER PLANT: One Walter HWK 109-509C-3 dual-chamber liquid-propellant rocket engine,main chamber rated up to 2,000 kp thrust, auxiliary chamber 400 kp thrust

PERFORMANCE: 590 mph

COMMENT: The Messerschmitt Me 263 „Scholle“ (Plaice) was a rocket-powered fighter aircraft developed from the Messerschmitt Me 163 „Komet“ (Comet) towards the end of WW II. Three prototypes were built but never flown under their own power as the rapidly deteriorating military situation in Germany prevented the completion of the test program.
Although the Messerschmitt Me 163 had very short endurance, it had originally been even shorter. In the original design, the engine had only one throttle setting, “full on”, and burned through its fuel in a few minutes. Not only did this further limit endurance, in flight testing, pilots found the aircraft quickly exhibited compressibility effects as soon as they levelled off from the climb and speeds picked up. This led the Reichsluftfahrtministerium (RLM) to demand the addition of a throttle, leading to lengthy delays and a dramatic decrease in fuel economy when throttled.
This problem was addressed in the slightly updated Messerschmitt Me 163C. This featured the same Walter HWK 109-509B or C dual chamber rocket engine already trialled on the Me 163B V6 and V18 prototypes; the main upper chamber („Hauptkammer“) was tuned for high thrust while the lower „Marschofen“ auxiliary combustion chamber was designed for a much lower thrust output (about 400 kgf maximum) for economic cruise. In operation, throttling was accomplished by starting or stopping the main engine, which was about four times as powerful as the smaller one. This change greatly simplified the engine, while also retaining much higher efficiency during cruise. Along with slightly increased fuel tankage, the powered endurance rose to about 12 minutes, a 50% improvement. As the aircraft spent only a short time climbing, this meant the time at combat altitude would be more than doubled.
Throughout development the RLM proved unhappy with the progress on the Me 263 project, and eventually decided to transfer development to Heinrich Hertel at Junkers company. Alexander Lippisch remained at Messerschmitt and retained the support of Waldemar Voigt, continuing development of the Me 163C.
At Junkers, the basic plan of the Me 163C was followed to produce an even larger design, the Junkers Ju 248. It retained the new pressurized cockpit and bubble canopy of the Me 163C, with even more fuel tankage, and adding a new retractable landing gear design. On September 1944 a wooden mock-up was shown to officials. The production version was intended to be powered by the more powerful BMW 109-708 rocket engine in place of the Walter power plant.
Prior to the actual building of the Ju 248, two Me 163Bs, prototype V13 and V18, were slated to be rebuilt. V13 had deteriorated due to weather exposure, so only V18 was rebuilt, but had been flown by test pilot Heini Dittmar at a record-setting 702 mph velocity on July , 1944 and suffered near-total destruction of its rudder surface as a result of high-speed induced compressibility. It is this aircraft that is often identified as the Me 163D, but this aircraft was built after the Ju 248 project had started.
Hertel had hoped to install Lorin ramjet engines, but this technology was still far ahead of its time. As a stopgap measure, they decided to build the aircraft with a „Sondergeräte“ (special equipment) in the form of a „Zusatztreibstoffbehälter“ (auxiliary fuel tank): two 160 l external T-Stoff oxidizer tanks were to be installed under the wings. This would lead to a 10% speed decrease but no negative flight characteristics. Although Junkers claimed the Ju 248 used a standard Me 163B wing, they decided to modify the wing to hold more C-Stoff fuel. This modification was carried out by the Puklitsch firm.
In November 1944, the aircraft was again redesignated as the Messerschmitt Me 263 to show its connection with the Me 163. The two projects also got names – the Ju 248 „Flunder“ (Flounder)) and the Me 263 „Scholle“ (Plaice)). In early 1945, Junkers proposed its own project, the EF 127 „Walli“ rocket fighter, as a competitor to the Me 163C and Me 263.
The first unpowered flight of the Messerschmitt Me 263 V1 was in February 1945. Several more unpowered flights took place that month. The biggest problem had to do with the center of gravity which was restored with the addition of counterweights. Eventually, the production aircraft would have repositioned the engine or the landing gear installation to solve this problem. The landing gear was still non-retractable. The results of those first flights were pricipally satisfying.
Test flights were later stopped because of fuel shortages for the Messerschmitt Bf 110 towplanes. As the Me 263 was not a part of the „Jägernotprogramm“ (Emergency Fighter Programm), it was difficult to get the resources it needed. For the time being the plane was not expected to enter production but further development was allowed. The V2 and V3 were not yet ready. The V2 was to get the retractable landing gear and the V3 would have the armament built in. The next month both the V1 and the V2 had the two-chambered HWK 109-509C installed, correcting the center-of-gravity problems. They flew only as gliders.
In April, American troops occupied the Messerschmitt plant and captured the three prototypes and the mock-up. The V2 was destroyed but another prototype ended up in the US. The rest was handed over to the Russians, who then created their own Mikoyan.Gurewitsch I-270 interceptor (Ref.: 24).

Fighter, Fighterbomber

Lockheed P-80A ‘Shooting Star’, 412th FG (Revell)

Gallery

TYPE: Interceptor fighter

ACCOMMODATION: Pilot only

POWER PLANT: One Allison J-33-A-35 turbojet engine, rated at 2,100 kp thrust

PERFORMANCE: 492 mph at 40,000 ft

COMMENT: The Lockheed P-80 Shooting Star was the first jet fighter used operationally by the USAAF. Designed and built by Lockheed Aircraft Company in 1943 and delivered just 143 days from the start of the design process, production models were flying but not ready for service by the end of WW II. Designed with straight wings, the type saw extensive combat in Korea with the United States Air Force (USAF) as the Lockeed F-80.
The prototype XP-80 had a conventional all-metal airframe, with a slim low wing and tricycle landing gear. Like most early jets designed during World War II – and before the Allies captured German research data that confirmed the speed advantages of swept-wings – the XP-80 had straight wings, similar to previous propeller-driven fighters. It was the first operational jet fighter to have its engine in the fuselage, a format previously used in the pioneering German Heinkel He 178 V1 of 1939, and the later British Gloster E.28/39 Pioneer demonstrator of 1941. Other early jets generally had two engines because of their limited power, these being mounted in external necelles for easier maintenance. With the advent of more powerful British jet engines, fuselage mounting was more effective, and it was used by nearly all subsequent fighter aircraft.
Concept work on the XP-80 began in 1943 with a design being built around the blueprint dimensions of a British Halford H-1 B turbojet (later called the de Havilland Goblin), a powerplant to which the design team did not have actual access. Lockheed’s team, consisting of 28 engineers, was led by the legendary C. L. „Kelly“ Johnson. This teaming was an early product of Lockheed’s Skunk Works, which surfaced again in the next decade to produce a line of high-performance aircraft.
The impetus for development of the P-80 was the discovery by Allied intelligence of the Messerschmitt Me 262 ‘Schwalbe’ (‘Swallow’) in spring 1943, which had made only test flights of its own first quartet (the V1 through V4 airframes) of design prototypes at that time, all fitted with retracting tailwheel landing gear. After receiving documents and blueprints comprising years of British jet aircraft research, the commanding General of the Army Air Forces, Henry H. Arnold, believed an airframe could be developed to accept the British-made jet engine, and the Materiel Command’s Wright Field research and development division tasked Lockheed to design the aircraft. With the Germans and British clearly far ahead in development, Lockheed was pressed to develop a comparable jet in as short a time as possible. Kelly Johnson submitted a design proposal in mid-June and promised that the prototype would be ready for testing in 180 days. The Skunk Works team, beginning 26 June 1943, produced the airframe in 143 days, delivering it to Muroc Army Airfield on 16 November.
The project was so secret that only five of the more than 130 people working on it knew that they were developing a jet aircraft, and the British engineer who delivered the Goblin engine was detained by the police because Lockheed officials could not vouch for him. After the engine had been mated to the airframe, foreign object damage during the first run-up destroyed the engine, which delayed the first flight until a second engine (the only other existing) could be delivered from Britain.
The first prototype was nicknamed „Lulu-Belle“ (also known as „the Green Hornet” because of its paint scheme). Powered by the replacement Halford H1 taken from the prototype de Havilland Vampire jet fighter, it first flew on 8 January 1944.The donated British jet program data had no doubt proved invaluable. In test flights, the XP-80 eventually reached a top speed of 502 mph at 20,480 ft, making it the first turbojet-powered USAAF aircraft to exceed 500 mph in level flight, following the August 1944 record flight of 502 mph by a special high-speed variant of the Republic P-47J Thunderbolt. Contemporary pilots, when transitioning to pioneering jets like the Shooting Star, were unused to flying at high speed without a loud reciprocating engine and had to learn to rely on the airspeed indicator.
The second prototype, designated XP-80A, was designed for the larger General Electric I-40 engine (an improved J31, later produced by Allison as the J33). Two aircraft were built. one was nicknamed the Gray Ghost after its “pearl gray” paint scheme, while the second aircraft was left unpainted for comparison of flight characteristics, became known as the Silver Ghost. The XP-80A’s first test flight was unimpressive, but most of the problems with the design were soon addressed and corrected in the test program. Initial opinions of the XP-80A were not positive and the aircraft were primarily testbeds for larger, more powerful engines and air intake design, and consequently were larger and 25% heavier than the XP-80.
The Shooting Star began to enter service in late 1944 with 12 pre-production YP-80As. A 13th YP-80A was modified to the sole F-14 photo reconnaissance model and lost in a December crash.
The initial production order was for 344 P-80As after USAAF acceptance in February 1945. A total of 83 P-80s had been delivered by the end of July 1945 and 45 assigned to the 412th Fighter Group (later redesignated the 1st Fighter Group) at Muroc Arma Air Field. Four were sent to Europe for operational testing (demonstration, familiarization, and possible interception roles), two to England and two to Italy, but after two accidents, one in England and one in Italy, the YP-80A was temporarily grounded. So the Lockheed Shooting Star saw no actual combat during the conflict.
After the war, the USAAF compared the P-80 and Messerschmitt Me 262 concluding, “Despite a difference in gross weight of nearly 900 kg, the Me 262 was superior to the P-80 in acceleration, speed and approximately the same in climb performance. The Me 262 apparently has a higher critical Mach number, from a drag standpoint, than any current Army Air Force fighter”.
Production oft he Shooting Star continued after the war, although wartime plans for 5,000 were quickly reduced to 2,000. A total of 1,714 single-seat F-80A, F-80B, F-80C, and RF-80s were manufactured by the end of production in 1950, of which 927 were F-80Cs (including 129 operational F-80As upgraded to F-80C-11-LO standards). However, the two-seat TF-80C, first flown on 22 March 1948, became the basis for the T-33 trainer, of which 6,557 were produced (Ref.: 24).