Aircraft / Aviation Vehicles & Artillery Small Arms Warships & Submarines Military Ranks Military Pay Chart (2024) Special Forces
Aviation / Aerospace

Saab J21

Prop / Jet Driven Fighter-Attack Aircraft [ 1945 ]

The Saab J21 appeared at the end of World War 2 as a prop-driven fighter only to later become a fully jet-powered platform in the J21R.

Authored By: Staff Writer | Last Edited: 03/29/2021 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

Sweden elected to remain neutral during the fighting of World War 2 (1939-1945) but this did not mean that it stood blind to the situation around it. The Soviet Union had invaded neighboring Finland and the Germans took Norway leaving Sweden as the lone Scandinavian power (Denmark too had fallen to the Germans on the European mainland). The Swedish Air Force drew up a request for a new modern fighter in 1941 intended to replace the now-obsolete American- and Italian-originated types that were still in frontline use for the service.

Design work on the aircraft followed and was led by Frid Wanstrom of Svenska Aeroplan AB. The team began with a single-seat, single-engine concept and this evolved to include a twin-boom layout. To provide for better forward views out-of-the-cockpit, the engine was set aft of the pilot in a "pusher" configuration. Not only was situational awareness a strong quality but the nose assembly was now free to be fitted with a collection of guns (as was the case with the American Lockheed P38 Lightning fighter). The pilot sat under a heavily-framed canopy and the raised fuselage spine restricted views to the rear. A straight monoplane wing planform was used that featured clipped tips and slight sweepback along the leading and trailing edges of the outboard planes. The empennage had a twin-finned configuration with a central plane joining the two fuselage booms. A modern tricycle undercarriage, fully retractable, rounded out the design elements which proved the aircraft rather innovative for its time.

The engine of choice became the German Daimler-Benz DB 605B 12-cylinder inverted Vee engine and this drove a three-bladed propeller unit at the rear of the cockpit nacelle, forcing air over and under the tail plane. Intakes were built into the wing leading edges (at the wing roots) to help aspirate the engine at rear. These powerplants would be built locally, under license, through SFA (Volvo Aero).

In terms of armament, the aircraft was given 1 x 20mm cannon along with 2 x 13.2mm machine guns and these were all fitted in the nose assembly. An additional 2 x 13.2mm machine guns were seen in the wings - one per wing.

A prototype made it to the air for the first time on July 30th, 1943 and two more followed for the test phase to come. The aircraft was given the designation of "J21" and Saab was charged with its serial production. The first operational-quality form became "J21A-1" and these served with the Flygvapnet through deliveries beginning in July of 1945. However, the war in Europe had ended in May of 1945 and the World War, in whole, would be over with the Japanese surrender of August. The Swedish Air Force took on a stock of 54 J21A-1 fighters nonetheless.

At the time of its adoption, the J21 was the only frontline fighter of pusher configuration to be adopted for service in World War 2. It was also the second fighter type anywhere in the world to feature an ejection seat as standard - this design element essentially forced upon engineers by the fact that the pilot would be vacating his doomed aircraft ahead of the spinning propeller blades - he simply could not roll off of the wing as usual and hope to clear the blades naturally. The German He 219 "Eagle-Owl" night-fighter became the first operational-level aircraft fitted with an ejection seat and the feature became standard on all fighters since.©MilitaryFactory.com
In practice, the J21A-1 was not an outright success for her pilots found her heavy at the controls and the engine proved a temperamental beast prone to overheating and, in turn, reducing the expected performance. The J21A-2 was brought along to remedy some of the initial failings of the A-1 model and mainly concentrated on internal revisions. From this point forward, the J21A was no longer considered a viable frontline fighter by the Swedish air service and thusly relegated to the attack role in the "J21A-3" guise. 119 were delivered to this revised standard between the span of May 1947 and January 1949 with the key quality of weapon hardpoints being added for the carrying of drop bombs, fuel and rockets. A bomb-aiming sighting device was also fitted for accuracy and there was support for RATO (Rocket-Assisted Take-Off) canisters for quick take-off and climbing-to-altitude.

The J21A-3 featured a length of 10.45 meters, a wingspan of 11.5 meters and a height of 3.97 meters. Its listed empty weight was 7,165 pounds with its Maximum Take-Off Weight (MTOW) rated at 9,730 pounds. Power was from a SFA (Daimler-Benz) DB 605B 12-cylinder liquid-cooled inline piston engine developing 1,475 horsepower. Maximum speed reached 400 miles per hour with a cruise speed nearing 310 miles per hour. Range was out to 465 miles and the reported service ceiling was 36,100 feet. Rate-of-climb was 2,950 feet-per-minute.

All was not over for the J21 for, in 1945, further work was had on the series in an attempt to fit the line with a turbojet engine - the British de Havilland "Goblin" to be exact - and attempt to bring more out of the design than initially intended. Saab engineers took aside four J21 airframes for the test phase and the aircraft was accordingly modified to take on a turbojet powerplant with side-mounted intakes and a longer, deeper fuselage nacelle. The design stayed largely faithful to the prop-driven form with about half of the original design being retained, expediting development and keeping costs in check. The converted aircraft were designated as "J21R" and a prototype first took to the air on March 10th, 1947.The Swedish Air Force commission for about 120 of this new form.

The J21R entered service during early 1950. Its standard armament fit was the 1 x 20mm cannon with 4 x 13.2mm heavy machine guns. Additional provision was added for it to take on an 8 x 8mm machine gun pack or 8 x 14.5cm rockets for the ground attack role. Once in service, the J21R did not reflect much of an improvement for the line - the airframe and its configuration were essentially a technological dead end in terms of aerodynamics for the aircraft's maximum speed clashed with the critical Mach number and controlling was still a poor quality. Range also suffered through the thirsty turbojet engine which restricted flying time to just 40 minutes and all this led to the air service reducing their intended stock to half - sixty fighters - thirty of the lot then became "J21RA" forms fitting the de Havilland "Goblin II" turbojet of 3,000lb thrust and the remaining thirty being of the "J21RB" with "Goblin III" engines of 3,305lb thrust output. Again, the line was pushed into the attack role as its primary mission set and received the new designation of "A21R". These aircraft served until July 1954 before being given up for good.

The J21R model exhibited a running length of 10.45 meters with a wingspan of 11.37 meters. Its empty weight was 7,055 pounds and a Maximum Take-Off Weight (MTOW) of 11,025 pounds was listed. Power from the Goblin II engine produced 3,100 pounds thrust providing a maximum speed of 500 miles per hour with a range of 450 miles and a service ceiling up to 39,400 feet.

Around 300 Saab J21 aircraft were completed. The J21B was a proposed form intended to carry a battery of 3 x 20mm cannons in the nose as well as radar within its starboard side boom assembly. The model would have been powered by a Rolls-Royce Griffon or Daimler-Benz DB 605E propeller-driving engine but this program fell to naught amidst the rise of jet-powered fighters seen in the period immediately following the end of World War 2.

The J21 was unique for its time aloft in that it began operational service as a prop-driven fighter and ended its days as a jet-powered mount. Few other aircraft were led down this development path and managed to see useful service lives.©MilitaryFactory.com
Note: The above text is EXCLUSIVE to the site www.MilitaryFactory.com. It is the product of many hours of research and work made possible with the help of contributors, veterans, insiders, and topic specialists. If you happen upon this text anywhere else on the internet or in print, please let us know at MilitaryFactory AT gmail DOT com so that we may take appropriate action against the offender / offending site and continue to protect this original work.


Saab - Sweden
Operators National flag of Sweden
Service Year
National Origin
Project Status

General ability to actively engage other aircraft of similar form and function, typically through guns, missiles, and/or aerial rockets.
Ability to intercept inbound aerial threats by way of high-performance, typically speed and rate-of-climb.
Developed to operate in close proximity to active ground elements by way of a broad array of air-to-ground ordnance and munitions options.

34.3 ft
(10.45 meters)
38.1 ft
(11.60 meters)
9.7 ft
(2.95 meters)
7,055 lb
(3,200 kilograms)
Empty Weight
11,001 lb
(4,990 kilograms)
Maximum Take-Off Weight
+3,946 lb
(+1,790 kg)
Weight Difference

1 x de Havilland Goblin II turbojet engine developing 3,307 lb of thrust (Daimler-Benz propeller pusher engine used in J21A).
497 mph
(800 kph | 432 knots)
Max Speed
39,370 ft
(12,000 m | 7 miles)
447 miles
(720 km | 389 nm)
4,600 ft/min
(1,402 m/min)

MACH Regime (Sonic)
RANGES (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hi-Hypersonic: 7673-19180 | Reentry: >19030

1 x 20mm Bofors (Hispano) cannon in nose
2 x 13.2mm Bofors (Colt) machine guns in nose
2 x 13.2mm Bofors (Colt) machine guns in wings (one per wing).

OPTIONAL (strike role):
8 x 13.2mm machine guns in ventral gun pack
8 x 14.5cm Air-to-Surface Unguided Rockets
4 x Conventional Bombs


J21 - Base Series Deisgnation
J21A-1 - Initial Production Model; 54 examples produced; fitted with Daimler-Benz pusher engine; ejection seat; 54 examples completed.
J21A-2 - Follow-Up Production Model; fitted with Swedish-made armament (20mm cannon); internal changes; 124 examples produced.
J21A-3 - Dedicated Attack Variant; Initial Production Model of that type series; based on the J21A-2; fitted with bombsight for strike operations; provision for undermounting of rockets and bombs; RATO optional; 66 examples completed.
J21B - Proposed Variant; fitted with 3 x 20mm cannons; radar installation in starboard boom; Daimler-Benz DB605E series engines OR Rolls-Royce Griffon series engines; never produced.
J21R - Jet-Powered Version Base Designation
J21RA - Fitted with de Havilland Goblin II series turbojet engine of 3,000lb thrust; 30 examples.
J21RB - Fitted with de Havilland Goblin III series turbojet engine at 3,305lb thrust; appearing in 1949 onwards; 30 examples.

Military lapel ribbon for Operation Allied Force
Military lapel ribbon for the Arab-Israeli War
Military lapel ribbon for the Battle of Britain
Military lapel ribbon for the Battle of Midway
Military lapel ribbon for the Berlin Airlift
Military lapel ribbon for the Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
Military lapel ribbon for pioneering aircraft
Military lapel ribbon for the Falklands War
Military lapel ribbon for the French-Indochina War
Military lapel ribbon for the Golden Age of Flight
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Indo-Pak Wars
Military lapel ribbon for the Iran-Iraq War
Military lapel ribbon for the Korean War
Military lapel ribbon for the 1982 Lebanon War
Military lapel ribbon for the Malayan Emergency
Military lapel ribbon representing modern aircraft
Military lapel ribbon for the attack on Pearl Harbor
Military lapel ribbon for the Six Day War
Military lapel ribbon for the Soviet-Afghan War
Military lapel ribbon for the Spanish Civil War
Military lapel ribbon for Special Forces
Military lapel ribbon for the Suez Crisis
Military lapel ribbon for the Ukranian-Russian War
Military lapel ribbon for the Vietnam War
Military lapel ribbon for Warsaw Pact of the Cold War-era
Military lapel ribbon for the WASP (WW2)
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2
Military lapel ribbon for the Yom Kippur War
Military lapel ribbon for experimental x-plane aircraft


1 / 1
Image of the Saab J21
Image copyright www.MilitaryFactory.com; No Reproduction Permitted.

Disclaimer | Privacy Policy | Cookies

2024 Military Pay Chart Military Ranks DoD Dictionary Conversion Calculators Military Alphabet Code Military Map Symbols

The "Military Factory" name and MilitaryFactory.com logo are registered ® U.S. trademarks protected by all applicable domestic and international intellectual property laws. All written content, illustrations, and photography are unique to this website (unless where indicated) and not for reuse/reproduction in any form. Material presented throughout this website is for historical and entertainment value only and should not to be construed as usable for hardware restoration, maintenance, or general operation. We do not sell any of the items showcased on this site. Please direct all other inquiries to militaryfactory AT gmail.com. No A.I. was used in the generation of this content; site is 100% curated by humans.

Part of a network of sites that includes GlobalFirepower, a data-driven property used in ranking the top military powers of the world, WDMMA.org (World Directory of Modern Military Aircraft), WDMMW.org (World Directory of Modern Military Warships), SR71blackbird.org, detailing the history of the world's most iconic spyplane, and MilitaryRibbons.info, cataloguing military medals and ribbons. Special Interest: RailRoad Junction, the locomotive encyclopedia.

©2023 www.MilitaryFactory.com • All Rights Reserved • Content ©2003-2023 (20yrs)