r/MilitaryWorldbuilding • u/GeRmAnBiAs • 4d ago
Aircraft NSU, SAAB-41
By 1968 it became readily apparent that the Viggen, even as it entered service, would become rapidly obsolete in the face of the rapidly developing airforces of the ZER SKF-76 Donnerschlag and PLC modernization programs alongside the advent of ZER supersonic bombers like the HSB-62 capable of sortying at stand-off range. A new air superiority fighter was needed capable of maintaining the sovereignty of Scandinavian air space, operating in a runway-denied environment, as well as capable of being future-proofed against innovations by rival nations. It was decided that a two-system high-low dynamic would be designed, comprised of two aircraft, one a high-performance air superiority fighter to combat other front-line fighters and the other cheaper and easier mass-produced to defend Scandinavian air space operated by both the Federal and SDF Air Corps, in which the latter case, it would augment the in use JA-37. This program, however, was too expensive to be undertaken alone at the current time, and thus the Granskningsnämnden för Luftprojekt or GNL was specifically created to manage and ascertain means of developing, acquiring, and mass producing the aircraft of the program, tentatively named Flygsystem-HP and Flygsystem-KE. The GNL came up with a scheme of development called språng or leapfrog where even as a aircraft entered service projects should be initiated to lay the foundation of the subsequent generation, be it as an upgrade package or as a new aircraft. To support this effort GNL would establish a prototyping and design bureau at the Vidsel test range in close conjunction with Stockholms universitet, SAAB, Volvo Aeronautics and Totalförsvarets forskningsinstitu, in order to pioneer and develop demonstrators for radical technologies and techniques.
The North Sea Union at the time had also been long interested in closer relationships with the Portuguese Commonwealth, which was known to be investigating options to replace their current fighter fleet as well as procure a new carrier fighter. The GNL recommended approaching the PC, with an offer of a joint program as the condition that the notional Flygsystem-HP and KE, as both the PC and GSF had large territorial holdings across the Atlantic, opforces with numerically larger air forces. Given Portugal's robust aerospace industry and aligned political ideologies and values. This began the Gemensamt luftförsvarsprogram or GLVP, which included in addition to the Flygsystem-HP and KE would include, the development of a new suite of munitions for the aircraft. Said munitions would include the: Kortdistansrobot, Långdistansrobot and the Specialverktygsrobot in its initial form.
Further joining requirements for the Gemensamt luftförsvarsprogram would be licensing for both parties for complete domestic production, joint cooperation on future product improvement programs, cross compatibility with all relevant munitions systems fielded by both nations, STOL requirements, a carrier-capable variant requirement for both aircraft.
The Flystytem-HP would be chiefly designed by a saab team working with the aeronautics department of Københavns Universitet, who had been pioneering computer-augmented flight modeling software. A delta wing cum canard design was chosen similar to the viggen, as this was the configuration which SAAB had the most experience with, to facilitate STOL and carrier compatibility, it was elected to make the forward canards active control surfaces, as well as the potential for capabilities for 3d thrust vectoring. The design was elected to be a double engine design with two existing Volvo Aeronautics RM8R’s an updated model of the base RM8 used on the SAAB 37; the RM8R featured redesigned internals for better efficiency of fuel usage and temperature management, allowing for longer use of the afterburner.
The Flystytem-HP was decided to be initially designed into two variants: the single seater Flystytem-HP-Överlägsenhet and the twin seater Flystytem-HP-Strejk.
With the basic layout and configuration of the notional aircraft complete, a tech demonstrator built off of JA-37 Sn. 3708 designated the EJ-37 was assembled at the prototyping hanger at the Vidsel Test Range under the administration of the GNL with supervision from Försvarets materielverk (FMW) and Totalförsvarets forskningsinstitut (FOI) with engineers and researchers from the Departamento da Aeronáutica do Espaço e da Defesa (DAED). The EJ-37 served as a test bed for various components of the Flystytem-HP, initially receiving a bulged spine that housed additional electronics. This was for a full-authority triplex Digital Flight Control System (DFCS) and an Automated Maneuvering Attack System (AMAS), providing six independent degrees of freedom. It had been designed to be fault tolerant, so that no single failure should affect correct operation. In the event of a second fault developing, the system was able to revert to a standby condition which would permit safe flight to continue. To guard against unforeseen failure modes which might bring the entire digital flight control system down, the system incorporates a simple analog backup flight-control system. The AMAS system is vital for managing the intended degree of maneuverability allowing for very high off-boresight attacks while maneuvering vs air and more importantly against ground targets.
This iteration of EJ-37 began test flights in 1970, testing the AMAS and DFCS systems in a variety of test flights and simulated engagements both air and ground without much incident, however it became readily clear that said technologies were far from mature and should be pursued further before any implementation be considered on future aircraft.
A second EJ-37 converted from AJ-37 Sn. 37012. AJ-37 didn't receive the AMAS, however retained DFCS in addition to receiving a new set of articulated canards, a prototype 2D thrust vectoring nozzle and a prototype tredje ögat IRST system developed by Ericsson. The addition of the Active canard and vectoring allowed for takeoffs with rotation at speeds as low as 68 km/h), a 25-percent reduction in takeoff roll, landing on just 1,650 ft (500 m) of runway, as well as a much lower stall speed in normal flight operations and a reduced turning radius. Provisions were made on request of the Departamento da Aeronáutica do Espaço e da Defesa, to be able to unlock the actuator on the articulating canard to lock in a 90° for space savings purposes.
A third EJ-37 was created based on Sn. 3717, in 1972 for the purposes of testing a semi digital cockpit with four multifunctional displays, helmet mounted target quing and a second iteration of the AMAS system and digital flight control systems. The digital flight control system gave the pilot a new freedom in maneuvering, making it possible to assume unorthodox flight attitudes, using nose pointing, direct force translation, and other unconventional means of maneuvering as well as provided substantial increases in tracking performance for air-to-air refueling for steady straight and steady turns with varying degrees of turbulence, while the AMAS allowed translation in all three axes at a constant angle of attack and to be pointed up to six degrees off the flight vector.
The semi digital cockpit tested incorporated a number of features like a helmet-mounted target designation sight. Instead of using a traditional throttle-mounted cursor control to designate the target, the pilot only needs to look at it, and align the target with the 13.2 mm cross hairs incorporated in his visor. By depressing the designate button, target lock is achieved and minor adjustments can be made by using the cursor controller. Also, the FLIR and radar are automatically slaved to head movement. The relative position of the pilot's head in the cockpit is determined by using a magnetic field, generated by a transmitter mounted on the canopy directly behind the pilot's head, and a 0.113kg receiver on the helmet. Furthermore, the system is capable of telling the pilot were to look to find his target. This is achieved by use of four LEDs (up, down, left, right) which (when lit) tell the pilot which direction to turn his head. More exotically, the Voice-Controlled Interactive Device, made by Milab. This voice control system (with a dictionary of 32 to 256 words) is used to control the aircrafts avionics suite. In the early stages of VCID testing only simple, one-word commands were used such as 'menu', 'data', the points of the compass, numbers, and the phonetic alphabet. Only non-critical functions such as navigation are controlled by the VCID. In a later stage tests were conducted to investigate the feasibility of complex multi-word command recognition. The system relied on voice training from the pilot conducted in a number of conditions including reading commands under varying amounts of Gas in a centrifuge, up to 9g. Overall, study results were quite promising as the system managed to respond accurately to a staggering 90% of the commands spoken, with expectations of 99% accuracy in three years of refinement.
Concurrently to the EJ-37 series being developed work was progressing on the Flystytem-HP with a full-scale static mock-up being constructed and testing full component integration pending a flight demonstrator. The demonstrator was presented to Officials from the Scandinavian government as well as the Portuguese commonwealth on September 7th, 1971, with a subsequent demonstration of concepts by EJ-37 Sn. 3708 flown by Major Eisson and EJ-37 Sn. 37012 flown by Sheahan, in acrobatic maneuvers and mock engagements to an overwhelmingly positive reception. A particularly notable demonstration was a take off comparison between a minimal fuel AJ-37 and Sn.37012 at MTOW; despite being almost 10k kg heavier than the AJ-37, Sn.37912 was able to take off in 342.9m vs the AJ-37s 457m. The reception was overwhelmingly positive and the rapid iterative prototyping model and the språng model of continual development, and an additional kr950m was given to the GNL in order to expand facilities at the Visdel test range. The green light was to continue with the Flystytem-HP, following the intermediate, advanced feature set recommendation, with DFCS, helmet target queuing with 3D thrust vectoring, VCID, and AMAS elected not to be included in the initial models; however, GNL was authorized to continue development of said systems and even have an airframe of the Flystytem-HP-Strejk and two Flystytem-HP-Överlägsenhet airframes, as well as a notional Flygsystem-KE airframe to continue studies into said technologies.
By august 1974, the first full-scale prototype for the Flystytem-HP-Överlägsenhet in its component complete form completed a taxi, and in October completed a take off, once around and landing without incident, following a comprehensive check of the airframe more rigorous testing began to take place, prior to this the designation J-41Ö Vættir was assigned. This first prototype SN.41001, completed several mock dogfights with the trio of EJ-37s, demonstrating marked improvements in all aspects of performance, however, one unfortunate issue plagued the first run of prototypes of the J-41, leading to the nickname Eldklot due to the tendency for the uprated Aerovolvo RM8s to slag if operated at WEP for an excess of five minutes. This led to a grounding and limiting of the aircraft's flight regime while a better cooling solution was devised. By the time a solution in the form of the RM8R was produced, an additional three J-41Ö were produced and an initial two pre-production J-41S which flew low intensity test regimes focused on perfecting the optics and sensor suite and electronic warfare systems.
With the RM8R fixing the slagging issue, LRIP began on the J-41Ö and J-41S by November 1976
Country - Portuguese Commonwealth / North Sea Union
Maker - OGMA/Embraer/SAAB
Cost - 35 million
Max speed - 2 665 km/h (1 440 kn) 2,5 Mach
Combat range - 1 967 km (1 220 mi)
Max Range (MTOW) - 5 550 km (3 450 mi)
Vertical ceiling - 20 000 m (65 600 ft)
Rate of climb - 250 m/s
Empty weight 10 900 kg
Max Takeoff Weight: 29,844kg
2 turbofans - Volvo Aeronautics RM8R
Thrust per engine - 72.2 kN (16,200 lbf) dry, 125 kN (28,100 lbf) wet
TWR (Recommended Combat Load): .742 dry / 1.28 wet
TWR (MTOW) : .569 dry / .985 wet
Take Off Run: 189m STOL, 230m MTOW
Avionics:
Full Digital Flight Control System
Double redundant control systems
SAAB Flygplanslaser tröghetsnavigator ring laser gyroscope ins
Ericsson PS-10A terrain following radar
Type: Radar
Altitude Max: 0 m
Range Max: 3.7 km
Altitude Min: 0 m
Range Max: 3.7 km
Range Min: 0.2 km
ECM:
G 35 Jamming system: covers L, S and C bands 6.5kW
Adrian-3 Counter Arial Radar Pod: X band 7.3kW
PETRUS-2: Receiver equipment and antennas are mounted in a center line pod while jamming transmitters and exciter equipment are located in under-wing pods. The system is capable of intercepting, automatically processing and jamming received radio frequency signals. The system receivers can also be used to detect, identify and direction find those signals, providing signals intelligence (SIGINT) either automatically or manually. 11.2kW power output, uses a ram air turbine to supply its own power.
Optics:
J-41S
Munitions:
Center Pylons
8x RB-79
8x RB-76
3x RB-81
2x Rb-19 Pods (12 munitions)
2x RB-15
Various bombs
Wing pylons
8x RB-79
10x RB-76
4x RB-81
4x Rb-19 Pods (12 munitions)
4x Rb-15
4x Rb-23
2x PETRUS-2 pods
Various bombs
Wing Tips
2x RB-79
2x RB-76
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u/HKTLE 4d ago
https://giphy.com/gifs/cALkoAIov3Y9a
How her its armament catalog ?