- Yes.
- No.
- Yes.
- No.
- (i said no.)
Backround
During the testing of the afterburner (EBK) for the J 34, the rear fuselage of aircraft 34007 was used for fitting and installing a mock-up of the EBK. It became evident early on that the engine in the J 34, with roughly 3,000 kp thrust, was too weak to provide the aircraft with satisfactory climb performance. The time from detecting a high-altitude approaching bomber formation to the engagement by the own fighters was entirely dependent on the fighter aircraft’s climb rate. Despite a high state of readiness and effective combat control, the J 34 would still fall short of meeting and attacking an enemy bomber formation in time. This was the dilemma of Swedish fighter aviation at that time.
The successful design and installation of the afterburner (EBK) in the J 29F aircraft definitively provided the fighter aviation with better opportunities in this regard. Consequently, the idea of possibly developing and installing an EBK in the J 34, which was otherwise a good weapon platform with relatively high firepower, was proposed.
Afterburner nozzle
Normal nozzle
On May 19, 1956, the Royal Air Board (KFF) issued a directive to the Test Center (FC) to investigate the feasibility of equipping the J 34 with an EBK!
In the spring of 1956, aircraft 34007 was transferred to the FC to be used as a static test object for the fitting and installation of an EBK mock-up with accompanying calculations. It was concluded that the aircraft’s fuel system (LT system) needed to be supplemented with a separate EBK pump and that the hydraulic system needed additional control valves and cylinders for adjusting a two-position nozzle.
Refueling on the line with reloading (changing of the cannon box) at the 3rd Division F 18 Tullinge in 1956. Initially, external drop tanks were never used as “interceptors” in Stockholm’s air defense! Note the squadron insignia on the forward fuselage of “Yellow Caesar.” Photo: See below.
Structural changes to the rear fuselage were also required in the form of mounting points, service hatches, etc., without altering the aircraft’s shape or dimensions. However, the tail cone had to be cut in line with the slanted frame 61 (see the technical description).
Following these preliminary studies, FC responded to KFF on October 11, 1956, stating that the EBK could be installed in the J 34 with modifications of approximately the same extent as for the installation of the EBK in the J 29. However, the problem was that the aircraft’s and thereby the EBK’s dimensions were predetermined. A relatively small diameter of the EBK itself meant higher and more critical gas velocity, which could jeopardize function and operational reliability—especially at high altitude. However, Flygmotor’s technicians claimed they could eliminate these problems.
In the autumn of 1956, KFF placed an order with SFA for the development and manufacture of six test examples of the EBK for the J 34, which received the project designation U56. On October 30, 1956, aircraft 34052 was transferred to FC for modification and EBK installation, followed by subsequent flight tests. 34052 went directly to FC after delivery, and the project was studied and monitored by Hawker’s own technicians, initially with great skepticism and later with explicit enthusiasm.
Aircraft 34052 was used for flight tests with a Swedish-designed afterburner for the J 34. Note the tail cone and exhaust nozzle as well as the scoop intake on the top of the fuselage! Photo: FS.
On March 8, 1957, another J 34 was transferred to FC immediately after delivery. The aircraft was 34085 and was used for comparative flight tests and evaluation of the type characteristics in connection with the EBK installation.
The actual flight tests began on May 6, 1958, after extensive ground tests and runs with the EBK ignited in aircraft 34052. The subsequent flight tests with the EBK ignited met the calculations, and the climb time to 12,000 meters was roughly 4 minutes! However, the previously noted concerns regarding the EBK’s small diameter meant it could only be effectively used up to 10,000 meters. At higher altitudes, the function deteriorated, and the EBK extinguished.
The EBK installation hardly changed the aircraft’s type characteristics, except for slight vibrations in the rudder at speeds above Mach 1. This could partly be attributed to separation issues at the truncated tail cone and did not affect the aircraft’s stability. This tendency could be disregarded as the purpose of the EBK installation was to improve the aircraft’s climb performance rather than its speed performance.
Swedish fighter aviation in 1957 over the “Sea of Peace,” i.e., the Baltic Sea, represented by a four-ship formation of J 34s from Södertörn Wing. Photo: Hans Bladh.
Without delving too deeply into all the adjustments, additional modifications, or the figures associated with the EBK tests, it is noted that the project was abruptly terminated on June 29, 1958.
There were several reasons for this. The cost of equipping the J 34 with an EBK was estimated at 24 million kronor. It was hardly a sensible investment given that the J 35 would soon be introduced to the fighter units, and that the J 34 was, after all, a “transition aircraft.” Furthermore, while the EBK would indeed increase the aircraft’s climb performance, it would come at the price of a very short action time due to increased fuel consumption of an already limited fuel capacity. Paradoxically, the J 34 would become a less effective fighter aircraft with an EBK!
At this time, it was assumed that the J 34 would have a relatively short lifespan in the Air Force in favor of the J 35. However, the tactical developments in the 1960s would place new demands on fighter aviation and its operations, in which the J 34 became more useful and effective! This may be a twist of fate. But aside from allocations related to impending unit withdrawals, the J 34 made a good and effective contribution to Swedish air defense throughout the 1960s! The limitations of the Draken in the 1960s extended the J 34’s service life—rightly so—despite its poorer climb performance.
The designation J 34B,
Which was internally assigned to the aircraft used for the EBK tests, should not be seen as an official type designation from a historical perspective.
(Authors Note:) However since this is the only documented name difference from the standard J34 i believe this should become its designation in War thunder.
Statistics/Qualities:
Armament
The testing and modifications for the afterburner installation did not change the fundamental armament capabilities of the aircraft. Therefore, the J34B retained the same armament configuration as the standard J34.
- Four 30 mm ADEN cannons
- Hardpoints for carrying external fuel tanks and/or rockets though the early interceptors rarely carried external tanks as noted in the translated document.
Dimensions
The dimensions of the Hawker Hunter (designated J34 in Swedish service), including variants like the J34B used for afterburner testing, are as follows:
- Length: Approximately 14.16 meters (46 feet 5 inches)
- Wingspan: Approximately 10.26 meters (33 feet 8 inches)
- Height: Approximately 4.01 meters (13 feet 2 inches)
Structural Changes:
- Fuel System Modifications: The fuel system was supplemented with a separate EBK pump.
- Hydraulic System Adjustments: Additional control valves and cylinders were installed to manage the two-position nozzle.
- Tail Cone Modification: The tail cone was cut in line with the slanted frame to accommodate the afterburner without altering the aircraft’s overall dimensions.
Flight performance
- Climb Rate:
- The modified J34 with the afterburner could climb to 12,000 meters (approximately 39,370 feet) in about 4 minutes. This was a significant improvement in climb performance compared to the standard J34 without an afterburner.
- Maximum Effective Altitude with Afterburner:
- The afterburner could be effectively used up to an altitude of 10,000 meters (approximately 32,808 feet). Beyond this altitude, the performance of the afterburner deteriorated, and it could extinguish.
- Overall Type Characteristics:
- Despite the improvements in climb performance, the afterburner installation did not significantly alter the overall flight characteristics of the aircraft. However, slight vibrations were noted in the rudder at speeds above Mach 1, attributed to separation issues at the modified tail cone.
Increased Fuel Consumption:
- The use of the afterburner greatly increased fuel consumption compared to normal engine operation. This is a typical characteristic of afterburners, which inject additional fuel into the jet exhaust to produce extra thrust, leading to higher fuel burn rates. While it is somewhat unknown exactly how long the fuel lasted, it can be speculated to be similar to the J29F since the afterburner design was based of it.
Summary
These improvements primarily enhanced the J34’s ability to intercept high-altitude targets more quickly, addressing a critical need for rapid response times in air defence scenarios. However, the increased fuel consumption due to the afterburner reduced the aircraft’s operational range and endurance.
Secondary Sources:
Fpl 34 – I Flygvapnet – Svensk Militär Flygplanshistorik (2024)
J 34 Hawker Hunter (2024)
Hawker Hunter in Swedish service (2024)
J34 Jaktflygplan Notis 2 (2024)
Authored books:
Nils Kindberg. Svensk flygindustri genom tiderna IV (.pdf)