Saab J21

History of the Saab J21

Sweden chose to remain neutral during World War II (1939-1945), but that did not mean it was blind to the situation around it. The Soviet Union invaded neighboring Finland, and the Germans occupied Norway, making Sweden the only Scandinavian power (Denmark also fell to Germans on the Continent).

In 1941, the Swedish Air Force requested a new modern fighter to replace the now obsolete American and Italian-made models still in front-line service.

The design of the aircraft was then led by Frid Wanstrom of Svenska Aeroplan AB. The team started with a single-seat, single-engine concept, which has since evolved into a two-arm layout.

To give the cockpit better forward visibility, the engines were placed in a "slider" configuration behind the pilot. Not only is situational awareness a powerful feature, but the nose assembly can now be equipped with a range of weapons (like the American Lockheed P38 Lightning fighter). The pilot sits under a heavy-frame canopy, with a raised fuselage spine limiting rear visibility.

A straight monoplane wing plane form was used, with a truncated tip and a slight setback along the leading and trailing edges of the outboard. The tail is in a twin tail configuration, with the center plane connecting two fuselage booms.

The modern, fully retractable tricycle landing gear rounded out the design elements that proved the aircraft to be quite innovative for its time.

The engine of choice was a German Daimler-Benz DB 605B 12-cylinder V12, which drove a three-blade propeller unit aft of the cockpit nacelle, which forced air above and below the tail. Air intakes are mounted on the leading edge of the wing (at the root of the wing) to help suck in the engines at the rear.

The power plants will be built on site under license from SFA (Volvo Aviation).

In terms of armament, the aircraft is equipped with 1 x 20mm cannon and 2 x 13.2mm machine guns, all housed in the nose assembly. Additional 2 x 13.2mm machine guns can also be seen on the wings - one for each wing.

On July 30, 1943, one prototype flew for the first time, followed by two more prototypes for the upcoming test phase. The aircraft was named "J21" and Saab was commissioned for serial production. The first operational form became the "J21A-1" and was delivered through the Flygvapnet from July 1945.

However, the war in Europe ended in May 1945, and the entire world war would end with the surrender of Japan in August. Nonetheless, the Swedish Air Force purchased 54 J21A-1 fighter jets.

At the time of its introduction, the J21 was the only propulsion front-line fighter used in World War II. It's also the second fighter in the world to have an ejection seat as standard - a design element basically imposed on engineers as the pilot leaves his doomed plane before the propeller blades turn - he just doesn't Knowing how to usually roll off the wings, hoping to release the leaves naturally.

The German night fighter He 219 "Eagle-Owl" was the first combat aircraft to be equipped with an ejection seat, a feature that has become standard on all fighters since then.

In practice, the J21A-1 was not entirely successful as its pilots found it difficult to control, and the engine proved to be a grumpy beast prone to overheating, which in turn reduced expected performance. The J21A-2 was introduced to address some of the initial shortcomings of the A-1 model, mainly focusing on internal modifications. Since then, the Swedish Air Force no longer sees the J21A as a viable front-line fighter and is therefore relegated to an attack role under the name "J21A-3".

Delivered between May 1947 and January 1949, 119 conformed to this revised standard, adding critical mass for weapons mounts used to carry dropped bombs, fuel, and rockets. Bomb sights are also installed for accuracy, and RATO (Rocket Assisted Takeoff) canisters are supported for quick launch and climb to high altitude.

The J21A-3 has a length of 10.45 meters, a wingspan of 11.5 meters and a height of 3.97 meters. Curb weight is listed at 7,165 lbs and maximum takeoff weight (MTOW) is 9,730 lbs. Power comes from an SFA (Daimler-Benz) DB 605B 12-cylinder liquid-cooled inline engine producing 1,475 hp.

Top speed reaches 400 mph and cruising speed is close to 310 mph. The range is 465 miles and the reported service is capped at 36,100 feet. The climb rate is 2,950 feet per minute.

The J21 wasn't over yet, further work on the series in 1945 was to equip the series with turbojets - British de Havilland "goblin" to be exact - and try to bring more out of the design than the original expectations. Saab engineers set aside four J21 airframes for testing and modified the aircraft to accommodate turbojets with side-mounted air intakes and a longer, deeper cabin. The design largely maintains the prop-driven form while retaining about half the original design, speeding development and keeping costs in check. The modified aircraft was named "J21R" and the prototype first flew on March 10, 1947.

The Swedish Air Force ordered about 120 of this new form.

The J21R entered service in the early 1950s. Its standard armament is 1 x 20mm cannon and 4 x 13.2mm machine guns. Added additional provision to accept 8x8mm machine gun packs or 8x14.5cm rockets as ground attack roles.

Once in service, the J21R did not reflect major improvements to the production line - the airframe and its configuration were basically a technical dead end in terms of aerodynamics, as the aircraft's top speed collided with a critical Mach number and the controls were still poor a kind of Quality is. The Range also suffered from a thirsty turbojet that limited flight time to 40 minutes, all of which led the Air Service to cut its planned inventory in half - sixty fighter jets - 30 of which became "J21RAs" " - Shaped with the De Havilland "Goblin II" 3,000 lb turbojet and the remaining 30 "J21RB" models with the 3,305 lb "Goblin III" engine.

The line was again pushed into the attack role as the main task group and received the new designation "A21R". The aircraft remained in service until July 1954 before they were finally scrapped.

The J21R model has a barrel length of 10.45 meters and a wingspan of 11.37 meters. It has a reported kerb weight of 7,055 pounds and a maximum takeoff weight (MTOW) of 11,025 pounds.

Power from the Goblin II engine produces 3,100 pounds of thrust, a top speed of 500 miles per hour, a range of 450 miles, and a service ceiling of up to 39,400 feet.

About 300 Saab J21 aircraft completed. The J21B is a proposed form designed to carry a set of 3 x 20mm guns and radar in its nose and starboard rudder assembly.

The model would be powered by either a Rolls-Royce Griffon or a Daimler-Benz DB 605E propeller-driven engine, but that plan was sabotaged in the face of the rise of jet fighters after World War II. [ /p]

The J21 was unique when it was in the air, as it began service as a propeller-powered fighter and ended its days as a jet-powered fighter. Few other aircraft have taken this development path and managed to reach the end of their useful life.

Specification

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