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2018-02-21

NOTES

 

J23AN  Angripare

Supermarine Attacker

The story which didn't happen ... outside Atlantic Air Combat
 
  See also : AAC Data Sheet
 
 
Illustrations :
 
 
Illustrations :
 
 
Related Pages :
 
 
 
 

Introduction
Having decided in 1956 to develop their blue water navy rather than scrapping it and purchase aircraft carriers relinquished by the Royal Navy (see: A2 HMS Gotland and A3 HMS Lappland) , Sweden was in need of carrier capable fighters and attack aircraft.   Lacking the time and ressource to develop a design of their own, the Swedish Navy sought to acquire existing designs.   In the end, a mixed solution was adopted in the form of rebuilding the straight wing J21R into a carrier capable attack aircraft and in the purchase of second hand, also straight winged, Supermarine Attacker.   A very conservative choice indeed, in deep contrast with what was being achieved by Saab for the Flygvapnet, where the J29 Tunnan was soon to be regarded as equal if not superior to existing designs of the time.   But while a separate Navy Air Arm had disappeared in the mid 1920's as it merged with the Air Force, the weight of a more conservative Naval Command dit play a role in this choice.

While the main attention was given to the rebuild of the remaining J21A/J21R into a fleet of J21RN aircrafts, a secondary type was regarded as an interim and safety measure.   As usual, Sweden was looking to play the number and their historical contacts with United Kingdom lead to the choice of the Supermarine Attacker, of which enough airframes remained available.   Also, three dozen of aircrafts had been sold to Pakistan, but the Pakistani Air Force was already contemplating to equip their 11 Squadron with F-86, potentially making these airframes also available to be transferred back to Europe.

SAAB already being over-busy with the production of both the J29 Tunnan and J32 Lansen, the development of the J35 Draken, not forgetting the J21RN rebuilding programme, the Kungliga Flygfφrvaltningens Flygverkstad i Stockholm which had been responsible for the design and production of the war time J22 was revived to look after these Supermarine aircrafts, bringing all airframes to a common standard.

The Pakistani Air Force finally refused to resell their (land based) Supermarine Attacker to Sweden, leaving KFFS with the FAA and Royal Naval Reserve as the sole source of aircrafts, which were received in the course of 1957, with a few airframes delivered late in 1959.  These late delivered (5 Attacker F1 and 4 Attacker FB2) sort of arrived a bit late to be incorporated in the rebuilt programme and since the targeted amount of 96 airframes had already been received, these nine airframes, which were flown to Sweden, were overhauled but not rebuilt, with the exception of the FB2 canopies which were replaced with remanufactured items.  These airframes were incorporated "as is" for liaison purposes.

Serial Prod Fate Date

Serial Prod Fate Date

Serial Prod Fate Date


















F1 WA469 1950 Ret 1955 01 1957 FB2 WK319 1952 Ret 1958 01 1959 FB50 G15110 1952 Ret 1964 =
F1 WA470 1950 Crash 1952   FB2 WK320 1952 Ret 1956 02 1957 FB50 G15177 1952 Ret 1964 =
F1 WA471 1950 Ret 1958 02 1959 FB2 WK321 1952 Ret 1957 03 1957 FB50 G15178 1952 Ret 1964 =
F1 WA472 1950 Ret 1953 03 1957 FB2 WK322 1952 Ret 1957 04 1957 FB50 G15179 1951 Ret 1964 =
F1 WA473 1951 Ret 1954 = FB2 WK323 1952 Ret 1956 05 1957 FB50 G15180 1951 Ret 1964 =
F1 WA474 1951 Ret 1958 04 1959 FB2 WK324 1952 Crash 1953   FB50 G15181 1951 Ret 1964 =
F1 WA475 1951 Crash 1952   FB2 WK325 1952 Ret 1956 06 1957 FB50 G15182 1951 Ret 1964 =
F1 WA476 1951 Ret 1955 05 1957 FB2 WK326 1952 Ret 1957 07 1957 FB50 G15183 1951 Ret 1964 =
F1 WA477 1951 Crash 1951  

FB2 WT851 1952 Ret 1956 08 1957 FB50 G15184 1951 Ret 1964 =
F1 WA478 1951 Ret 1955 06 1957 FB2 WK327 1952 Ret 1956 09 1957 FB50 G15185 1951 Ret 1964 =
10 10 10
F1 WA479 1951 Ret 1958 07 1959 FB2 WK328 1952 Crash 1956   FB50 G15186 1951 Ret 1964 =
F1 WA480 1951 Crash 1951   FB2 WK329 1952 Crash 1952   FB50 G15187 1951 Ret 1964 =
F1 WA481 1951 Ret 1954 08 1957 FB2 WK330 1952 Crash 1954   FB50 G15188 1951 Ret 1964 =
F1 WA482 1951 Crash 1951   FB2 WK331 1952 Ret 1956 10 1957 FB50 G15189 1952 Ret 1964 =
F1 WA483 1951 Ret 1953 09 1957 FB2 WK332 1952 Ret 1955 11 1957 FB50 G15190 1952 Ret 1964 =
F1 WA484 1951 Ret 1956 10 1957 FB2 WK333 1952 Ret 1957 12 1957 FB50 G15191 1952 Ret 1964 =
F1 WA485 1951 Crash 1952   FB2 WK334 1952 Crash 1953   FB50 G15192 1952 Ret 1964 =
F1 WA486 1951 Ret 1956 11 1957 FB2 WK335 1952 Crash 1953   FB50 G15193 1952 Ret 1964 =
F1 WA487 1951 Ret 1956 12 1957 FB2 WK336 1952 Ret 1957 13 1957 FB50 G15194 1952 Ret 1964 =
F1 WA488 1951 Ret 1956 13 1957 FB2 WK337 1952 Ret 1957 14 1957 FB50 G15195 1952 Ret 1964 =
20 20 20
F1 WA489 1951 Ret 1958 14 1959 FB2 WK338 1952 Ret 1956 15 1957 FB50 G15196 1952 Ret 1964 =
F1 WA490 1951 Crash 1952   FB2 WK339 1952 Crash 1953   FB50 G15197 1952 Ret 1964 =
F1 WA491 1951 Ret 1956 15 1957 FB2 WK340 1952 Crash 1954   FB50 G15198 1952 Ret 1964 =
F1 WA492 1951 Crash 1953   FB2 WK341 1952 Ret 1957 16 1957 FB50 G15199 1952 Ret 1964 =
F1 WA493 1951 Crash 1952   FB2 WK342 1952 Ret 1957 17 1957 FB50 G15200 1952 Ret 1964 =
F1 WA494 1951 Ret 1956 16 1957 FB2 WP275 1952 Crash 1956   FB50 G15201 1952 Ret 1964 =
F1 WA495 1951 Crash 1954   FB2 WP276 1952 Ret 1957 18 1957 FB50 G15202 1952 Ret 1964 =
F1 WA496 1951 Ret 1954 17 1957 FB2 WP277 1952 Ret 1956 19 1957 FB50 G15203 1952 Ret 1964 =
F1 WA497 1951 Crash 1952   FB2 WP278 1952 Ret 1954 20 1957 FB50 G15204 1952 Ret 1964 =
F1 WA498 1951 Crash 1952   FB2 WP279 1952 Ret 1956 21 1957 FB50 G15205 1952 Ret 1964 =
30 30 30
F1 WA505 1951 Ret 1954 18 1957 FB2 WP280 1952 Ret 1956 22 1957 FB50 G15206 1953 Ret 1964 =
F1 WA506 1951 Ret 1953 19 1957 FB2 WP281 1953 Crash 1955   FB50 G15207 1953 Ret 1964 =
FB2 WA507 1952 Ret 1956 20 1957 FB2 WP282 1953 Ret 1954 23 1957 FB50 G15208 1953 Ret 1964 =
F1 WA508 1951 Ret 1956 21 1957 FB2 WP283 1953 Crash 1956   FB50 G15209 1953 Ret 1964 =
F1 WA509 1951 Crash 1952   FB2 WP284 1953 Ret 1956 24 1957 FB50 G15210 1953 Ret 1964 =
F1 WA510 1951 Crash 1954   FB2 WP285 1953 Ret 1957 25 1957 FB50 G15211 1953 Ret 1964 =
F1 WA511 1951 Crash 1952   FB2 WP286 1953 Ret 1957 26 1957
F1 WA512 1951 Ret 1954 22 1957 FB2 WP287 1953 Ret 1956 27 1957
F1 WA513 1951 Ret 1958 23 1959 FB2 WP288 1953 Crash 1954  
F1 WA514 1951 Ret 1955 24 1957 FB2 WP289 1953 Ret 1956 28 1957
40 40
F1 WA515 1951 Ret 1955 25 1957 FB2 WP290 1953 Ret 1957 29 1957
F1 WA516 1951 Ret 1955 26 1957 FB2 WP291 1953 Ret 1956 30 1957
F1 WA517 1951 Crash 1953   FB2 WP292 1953 Ret 1954 31 1957
F1 WA518 1951 Ret 1957 27 1957 FB2 WP293 1953 Crash 1953  
F1 WA519 1951 Ret 1957 28 1957 FB2 WP294 1953 Ret 1953 32 1957
F1 WA520 1951 Ret 1956 29 1957 FB2 WP295 1953 Ret 1954 33 1957
F1 WA521 1951 Ret 1957 30 1957 FB2 WP296 1953 Ret 1954 34 1957
F1 WA522 1951 Crash 1952   FB2 WP297 1953 Ret 1958 35 1959
F1 WA523 1951 Crash 1955   FB2 WP298 1953 Ret 1954 36 1957
F1 WA524 1951 Crash 1952   FB2 WP299 1953 Ret 1954 37 1957
50 50
F1 WA525 1951 Ret 1957 31 1957 FB2 WP300 1953 Crash 1954  
F1 WA526 1951 Crash 1952   FB2 WP301 1953 Ret 1956 38 1957
FB1 WA527 1951 Ret 1955 32 1957 FB2 WP302 1953 Ret 1957 39 1957
FB1 WA528 1951 Ret 1954 33 1957 FB2 WP303 1953 Ret 1954 40 1957
FB1 WA529 1952 Ret 1954 34 1957 FB2 WP304 1953 Crash 1954  
FB1 WA530 1952 Ret 1954 35 1957 FB2 WZ273 1953 Ret 1956 41 1957
FB1 WA531 1952 Ret 1957 36 1957 FB2 WZ274 1953 Ret 1956 42 1957
FB1 WA532 1952 Ret 1954 37 1957 FB2 WZ275 1953 Ret 1957 43 1957
FB1 WA533 1952 Ret 1954 38 1957 FB2 WZ276 1953 Ret 1955 44 1957
FB1 WA534 1952 Ret 1955 39 1957 FB2 WZ277 1953 Ret 1956 45 1957
60 60
FB1 WA535 1952 Crash 1953   FB2 WZ278 1953 Ret 1957 46 1957
FB2 WZ279 1953 Ret 1955 47 1957
FB2 WZ280 1953 Ret 1954 48 1957
FB2 WZ281 1953 Ret 1957 49 1957
FB2 WZ282 1953 Ret 1956 50 1957
FB2 WZ283 1953 Ret 1957 51 1957
FB2 WZ284 1953 Ret 1954 52 1957
FB2 WZ285 1953 Crash 1954  
FB2 WZ286 1953 Ret 1957 53 1957
FB2 WZ287 1953 Ret 1956 54 1957
70
FB2 WZ288 1953 Ret 1956 55 1957
FB2 WZ289 1953 Ret 1955 56 1957
FB2 WZ290 1953 Ret 1954 57 1957
FB2 WZ291 1953 Ret 1957 58 1957
FB2 WZ292 1953 Crash 1956  
FB2 WZ293 1953 Ret 1956 59 1957
FB2 WZ294 1953 Ret 1958 60 1959
FB2 WZ295 1953 Ret 1958 61 1959
FB2 WZ296 1953 Ret 1954 62 1957
FB2 WZ297 1953 Ret 1957 63 1957
80
FB2 WZ298 1953 Ret 1954 64 1957
FB2 WZ299 1953 Ret 1957 65 1957
FB2 WZ300 1953 Crash 1956  
FB2 WZ301 1954 Ret 1957 66 1957
FB2 WZ302 1954 Crash 1955  


















  - - - - 34 - - - - - - 62 - 36 - - - - =
61 - - - - 5 - 85 - - - - 4 - - - - - - =

The above (fantasy) data is based on researchs conducted by Nathan Decker and published on http://www.millionmonkeytheater.com/Attacker.html 

With a top speed of 513 knots, the Supermarine Attacker was certainly not a slow aircraft.  However, in view of improving its load carrying capacities (fuel or ammunitions) and general performances, the decision had been made to re-engine the Attackers with the last iteration of Rolls Royce centrifugal engine : the RB44 Tay.   Essentially designed to satisfy the need of the US Navy for a more powerful engine intended for upgraded version of the F9F Panther, it would be produced by STAL under the RM7 designation both for the Saab 21RN and the rebuild Supermarine Attacker now designated J23.  While not affecting the top speed considerably, which was restricted for aerodynamical reasons, the additional thrust would ensure the aircraft to take off safely at a significantly higher gross weight.

Aircraft

Engine

 

Thrust
Kgp

   Ψ   
mm

Length
mm

Weight
Kg

SFC

 












 F1

RR.RB41

Nene.101

2315

1257

2460

700

1.06

 FB1

RR.RB41

Nene.101

2315

1257

2460

700

1.06

 FB2

RR.RB41

Nene.102

2270

1257

2460

700

1.06

 FB50

RR.RB41

Nene.103

2361

1257

2460

700

1.06

 F9F2

PW

J42PW6

2270

1257

2460

700

1.06

 

STAL

RM3A

2350

1257

2460

700

0.92












 

RR.RB44

Tay

3507

1270

2621

935

1.10

 F9F5

PW

J48PW8

3292

1270

2621

935

1.10

 FB52/J23

STAL

RM7

3430

1270

2621

935

0.92

If some of the aircrafts were actually flown to Sweden and and were thus tested in their original form, all airframes were destined to be dismantled completely.   The Attacker project may have started as an interim ad hoc fighter programme, but as time went on, it became clear that a replacement wasn't to be become available before some ... distant future.  KFFS didn't have blank cheque to rebuild a new aircraft from scratch but at least they knew what was expected from them : to squeeze the utmost from this funny airframe as they were now intended to last..   And it had been a fine idea not enthrust the programme with SAAB.  Not that they lacked competence but somehow there were a bit conservative while a bolder approach was needed.  KFFS had sounded their colleagues to take advantage of their expertise, but only to discover SAAB reluctancy to even discuss the matter.  Clearly KFFS would be on their own for this one.

One thing was clear : there was no need to turn the Attacker into a fighter-bomber or attack airplane as the J21RN would clearly fill that role.   What was expected from KFFS was to turn this tail sitter into a fighter to protect the fleet.   With the Soviet navalizing their efficient MiG.17 and probably their supersonic MiG.19, the challenge was a serious one.

Both KFFS and the Swedish Navy were convinced even a subsonic fighter could counter the MiG.19.  Supersonic performances would be better naturally, but contrary to the thinking of the day, they both were of the opinion that most air combat would turn out to be a game of interception and missile firing before, perhaps, ending up in a dog fight, rather than a supersonic "hit and run" around which, for example, the F-104 Starfighter was designed.   So missile armament was a must, and loiter time in the patrol area, say about 150 nautical miles from the carrier, a key issue.

Weight Saving and Structural Modifications

Having had the opportunity to fly and maintain both the Supermarine Spitfire and the North American P-51D Mustang, and having had access to both the DH Venom and F-86F Sabre, the Swedes knew that the British still had to learn a little about structural weight.   Just for the sake of comparison, the FH-1 Phantom would show an engine less empty weight of 2400kg, compared to the 3665kg of an engine less Attacker...   So, a lot could be done in that area, and having completely dismantled a first airframe to study the matter, clearly half a ton could be saved by the adoption of lighter accessories and the removal of redundant parts.   With all the modern equipment to be accommodated (radar, radio and navigation equipement), this little weight saving operation was a real bonus.

Among the structual changes carried out on the airframes was the replacement of the part of the wing outside the guns box.   Partly because it had to be made stronger in order to carry fuel and allow for underwing ordnance, but also because only a small portion of the wing would fold.   Replacing the outer part of the wings allowed for a repositionning of the wing folding mechanism, now electrically operated, which would considerably reduced the "foot print" of the aircrafts whence wings were folded.

Finally, the British had encountered difficulties with their initial canopy design, with later variants of the Attacker adopting a framed construction.   The new design might be stronger, avoiding the cracks experienced with the original design, but it was indeed strange that the inventors of the bubble canopy (Hawker Typhoon) could not manage to produced proper items any more...   When acquiring the various airframes that had survived their (short) operational life with the FAA, Sweden ended up with a mix of F1, FB1 and FB2 airframes, and thus a mix of canopy types.   KFFS redesigned that part and had airframes refitted with a remanufactured "clear" bubble canopy, offering superior visibility for the pilot.

Fuel Capacity

Little could be done within the fuselage, as Supermarine had really squeeze the maximum in there, amounting to 1330 litres, small wing tanks inclusive.   In order to free the two only wing pylons for ordnance, a conformal 270 Imp Gal (1227 litres) belly fuel tank had been adopted by the British.   Surprisingly, this didn't affect the aircraft performances too much.   A any rate, a total of 2500 litres of fuel was certainly desirable, but engineers at KFFS thought that not only fuel tankage needed to be revised but also the gun layout.   Associated with the fact that only a small portion of the wing as foldable, it was decided to rebuilt the wing outside the gun box, with the guns themselves being removed, while a much stronger hinging mechanism was adopted.

If the wing was already holding a small fuel tank behind the wheel well, it now could hold a stunning total of 900 litres.  The wing pylons didn't need to be reinforced as they soon were cleared to carry loads of up to 1000 lbs (from the original 500 lbs), a compliment to Supermarine strong design.  It was however modified to allow the carriage of external fuel tanks.  Outside of the new hinging position was now a second pylon intended to carry air-to-air missiles, either a pair of AIM-9B Sidewinder or a single AIM-7C Sparrow.   While not asked for by the Navy, KFFS maintained to possibility to carry HVAR rockets, either British made RP3 or Bofors 135mm, thus still offering the rebuilt Attacker a secondary attack role.   Finally, while KFFS refrained from making provision for wing tip fuel tanks, the new wing offered the possibility to install AIM-9B missiles at the tips (or 135mm HVAR for that matter).  Considering the extra weight of the new radar (see below) and new engine, ending up with a MTOW a mere 900kg higher than the original design while enjoying a 50% increase in available power, FKKS could be satisfied to have met the Navy requirement and beyond.

Aircraft Thrust
Kgp
– Body Motor Main
Fuel
Main
Wings
Tips
Fuel
Belly
Fuel
Guns:500
x20mm
Pylons
Outer
500lbs
Pylons
Inner
1000lbs
HVAR Fuel
Total - L
Weight
Total Kgs















FB.2
RB41
2270 Kg 3665 700 1011 – – 983 115 12x27
=328
454
454
12x37
444
– 7870
– – L –
–
–
–
1330 –
–
–
–
1227 –
–
–
–
–
–
–
–
–
2557
–
–
- Range nmi – – xxx – – 1035 nm – – – – – –
J23
RM7
3430 Kg 3705 935 1011 1368 170 - 170 250
250
454
454
10x65
650
- 8767
- - L - - 1330 1800 - - - - 530
530
-
4190
-

Armament

Guns - As seen above, one of the items to be questioned was the gun layout.  The Hispano Suiza Mk5 autocannons were fine weapons, but positioning them in the wings sort of anihiliated their peformance, restricting the effective range to an aiming position roughly 500m ahead of the plane if not closer, beyond which shell disperstion reduced their effectiveness.   With the nose not being available for guns intallation, FKKS repositioned them in the conformal belly, allowing the gun quarted to be used to their full advantage..   Besides, no one could really be comfortable with the idea of making a wheels up landing on a belly filled with fuel vapors.   While the vast volume offered by this conformal belly was to be used for repositioning avionics from the nose, it nevertheless offered enough room to increase the amount of rounds per gun, now totalling 185rpg instead of the original 125rpg.

Air-to-Air Missiles - Initially, the quest was restriced to close range combat missiles, either British made FireStreak or US made AIM-4 Falcon.   In fact, the Swedish Air Force was already negociating the purchase of the Falcon missile but contacts between the Swedish and the US Navies lead the Swedes to select the Sidewinder.   Then, the US Navy was also developping a longer range missile, the AIM-7 Sparrow.   While still a highly classified item, Sweden had nevertheless been authorized to consider this weapon among their potential purchase.   Considering that threats to their Artic fleet could not only come in the form of carrier borne fighter-bombers but also in the form of long range bomber equipped with stand off weapons, the Sparrow was examined more closely before being adopted once the feasibility of a proper radar installation had been explored positively.

Radar - Sweden being one among few countries having almost full access to US military technonogy, compatibility of the Supermarine airframe with the APQ-51B X-band radar was examined with a positive result.  Although a tight fit for this relatively small sized aircraft, and quite a headache to solve the electrical circuitery and power issues it nevertheless fitted and offered the Swedish Navy with a true all weather interception capacity, with the radar offering a detection range of up to 28 NM for bomber sized targets, and 11 NM for fighter sized targets.

Wing Pylons - As mentioned, the original wing pylon was soon cleared for loads of up to 1000lb, essentially aimed to carry 530L fuel tanks, although they could be made to fire an 135mm HVAR, or carry more AIM-9B or AIM-7C air-to-air missiles, a rocket pod or even a pair of 500lb bombs (carried in tandem).  Then a second pylon was installed on the outer wing, essentially tailored to carry a pair of AIM-9B Sidewinder or a single AIM-7C Sparrow.  If needed, it could also carry a 500lbs bomb or any similar load.   These two pylons were spaced in such a manner that rocket rails could easily be installed under the wing, with one neatly placed between the two above mentioned pylons, plus another two further outboard of the external pylons.   As mentioned, contrary to what the Fleet Air Arm had done when developping the Attackeer F1 into the FB.2, the Swedish revised Attacker was not supposed to fulfill a secondary attack role.   However, FKKS did pay attention to properly design the underwing weapons carrying setup in order to offer maximum flexibility of use.  While in its original FB.2 format, the Attacker could carry RP3 rockets staged in pairs (for of total of 12), the carrying of RP3 was not compatible with the use of the under wing pylon.  The new wings were actually provided with 6 weapon positions, wing tips inclusive, vastly improving the potential of the aircraft.

Then, however cleverly re-designed, the Attacker wasn't intended for air-to-surface role and its typical armament would consist of two AIM-7C Sparrow on the outer wing positions, a pair of AIM-9B on the wing tips and a pair of 530 litres fuel tanks on the inner wing pylons, supplemented with the belly guns quartet.

Colors and Markings

Along the tradition of the Flygvapnet, the new F24 and F25 Wings were divided into three squadrons, the first Squadron showing Wing markings in red (X and Y being the 24th and 25th letter of the alphabet), the second squadron in blue and the third squadron in yellow.   Besides these typical Swedish markings, the aircrafts were finished in a not less typical medium green/grey topsides with pale grey underneath.

 

Wing F24

1St Sq

-

Wing F25

1St Sq

-

Wing F24

2nd Sq

-

Wing F25

2nd Sq

-

Wing F24

3rd Sq

-

Wing F25

3rd Sq

-

 

 

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