The Saab 18 was a twin-engine bomber and reconnaissance aircraft, designed and built by Svenska Aeroplan AB (SAAB) for use by the Swedish Air Force in response to a 1938 design competition.
Due to delays, it did not enter service until 1944, but quickly became the standard Swedish bomber aircraft.
Serving in the bomber, reconnaissance and ground attack roles, it also assisted in the development of ejection seats and air-to-surface guided missiles until its replacement by the Saab Lansen in the late 1950s.
Intended as a replacement for the Junkers Ju 86 in service with the Swedish Air Force, the requirement that led to the Saab 18 called for a three-seat fast reconnaissance aircraft.
AB Svenska Järnvägsverkstädernas Aeroplanavdelning (ASJA), SAAB, and AB Götaverken (GV) submitted designs for consideration by the Swedish Air Force.
GV’s GV8 appeared to be the best suited to the requirement; however, its cost and the departure of their chief designer resulted in SAAB the company having merged with ASJA in the meantime being awarded a contract for development of their design.
As a number of Americans were on the design staff of SAAB and ASJA, the Saab 18’s design shared some similarities with American designs.
The outbreak of World War II in 1939 led to a change of priorities by the Swedish Air Force, and production of the Saab 17 was accelerated, at the expense of work on the Saab 18, which, along with a change of requirements that added the role of medium bomber to the specification, resulted in the first flight of the aircraft being delayed until 19 June 1942.
Manned by a crew of three a pilot and navigator under a glazed, offset canopy, and a bombardier in the nose the Saab 18 prototype was a mid-wing monoplane with twin vertical stabilisers, and was powered by two Pratt & Whitney R-1830 Twin Wasp radial engines.
Armament consisted of three 13.2-millimetre (0.52 in) machine guns, one fixed firing forwards and controlled by the pilot, the others being in flexible defensive mounts for use by the navigator and bombardier.
Up to 1,000 kilograms (2,200 lb) of bombs could be carried in an internal bay, while up to eight 50-kilogram (110 lb) bombs could be carried on underwing hardpoints.
Flight testing showed that the aircraft was underpowered.
However, as there was no immediate prospect for the acquisition of more powerful engines, the Saab 18 was ordered into production in both bomber (B 18A) and reconnaissance (S 18A) versions.
Variants
Saab 18
One SFA STWC-3 engine B 18A prototype.
The same prototype was later re-engine with SFA DB 605B engines as the prototype for the B 18B.
B 18A
The first production version, bomber aircraft powered by two SFA STWC-3 Twin Wasp radial piston engines and armed with three 13.2 mm akan m/39A auto cannons, one fixed, two movable for defence.
The B 18A was quickly into its service life equipped with bomb forks to be able to dive bomb.
All were converted into S 18A reconnaissance planes in 1946-47.
S 18A
Photo-reconnaissance conversion of B 18A, fitted with PS-18/A radar among other modifications.
B 18B
Dive bomber version, powered by two Daimler-Benz DB 605B piston engines.
It was at the start armed with the same 3 auto cannons as the B 18A but it was quickly downgraded to 2 due to the lower defensive one being borderline useless due its limited traverse and the limited view for the gunner.
In 1946 the Swedish rocket-development program started and the B 18B was one of the planes used to test rockets of different types.
In 1949-1950 all planes were redesignated as attack aircraft and got the ability to equip 12 light rockets or 8 light rockets and 2 heavy rockets.
During the same period they also got ejection seats for the pilot and radio operator. Due to this the bombardier had to be removed and the radio operator lost his defensive gun.
The defensive gun had become obsolete either way due to the jet era.
Many of the planes that received ejection seats were also modified with a new rounded windshield.
Very late into its service life it was used effectively as a reconnaissance plane where it mainly dropped flare bombs and got the same PS-18/A radar as the S 18A. 119 built.
T 18B
Attack version, powered by the same engines as the B 18B.
It was armed with the same fixed and upper defensive auto cannon as the B 18B, but had 2 x 20 mm akan m/41 guns fixed in the nose.
It had a bigger bomb bay originally designed for a torpedo, but the aircraft could equip a 1000 kg m/47 medium-capacity/general-purpose bomb or a 57 mm akan m/47 auto cannon with 41 rounds instead, besides the original bomb load outs of the B 18B.
Early into its service it was also tested with the RB 302 anti-shipping missile which never entered service.
In 1949 it received the same rocket and ejection seat upgrades as the B 18B, but could only carry 8 light rockets.
In 1949 it was also tested with twin Bofors 40 mm L70’s in place of its iconic 57 mm but the recoil shattered the nose glass, ending the tests. 52 built.
B 18A Dubbelkommando
Trainer version where the radio operator seat was turned around for an instructor.
The armoured shield between the seats blocked the instructor’s view, but the conversion was considered worth it in the end as no new trainers had to be purchased and the plane could easily be reconverted for combat duty.
B 18B Dubbelkommando
Same idea as mentioned above but implemented on the B 18B.
Specifications
B-18B
Crew
3
Length
13.23 m (43 ft 5 in)
Wingspan
17.4 m (57 ft 1 in)
Height
4.35 m (14 ft 3 in)
Wing area
43.75 m2 (470.9 sq ft)
Empty weight
6,093 kg (13,433 lb)
Max take-off weight
8,793 kg (19,385 lb)
Fuel capacity
1,700 litres (370 imp gal; 450 US gal)
Powerplant
2 × SFA DB-605B inverted-vee piston engines,
1,100 kW (1,475 hp) each (1700 with modifications)
Propellers
3-bladed VDM-33 (German propeller licenced built in Sweden)
Performance
Maximum speed
575–590 km/h (357–367 mph, 310–319 kn) depending on altitude
Cruise speed
550 km/h (340 mph, 300 kn)
Stall speed
80 km/h (50 mph, 43 kn)
Range
2,600 km (1,600 mi, 1,400 nmi)
Service ceiling
9,800 m (32,200 ft)
Armament
Guns
1x 13.2 mm fixed akan m/39A forwards firing gun in wing root with 300 rpg
1x 13.2 mm movable akan m/39 defensive gun with 300 rpg
B 18B’s delivered early had a second movable 13.2 mm akan m/39 defensive gun with 300 rpg for the scout (a leftover from the B 18A).
This was quickly removed in the field due to the impracticality of it post-war and later production examples where delivered without it.
Loadouts
Formally
1,400 kilograms (3,100 lb) of bombs or 1,500 kilograms (3,300 lb) of bombs and rockets
Its biggest loadout was 2x 600 kg bombs and 12x rockets simultaneously.
Rockets
Outer wings
299 kg max
8x 8 cm pansarraket m/46 AP-rocket (RP-3 rocket with Shot, 25 lb., “AP” Mk II head)
8x 15 cm sprängraket m/46 HE-rocket (RP-3 rocket with Shell, H.E. 60 lb., “SAP” No. 2 Mk I head)
8x 14,5 cm pansarsprängraket m/49A & B HEAT-rocket (Bofors 10.3 cm rocket with 14,5 cm HEAT head)
8x 15 cm sprängraket m/51A & B HE-rocket (Bofors 10.3 cm rocket with 15 cm HE head)
Belly
240 kg
4x 8 cm pansarraket m/46 AP-rocket (RP-3 rocket with Shot, 25 lb., “AP” Mk II head)
4x 15 cm sprängraket m/46 HE-rocket (RP-3 rocket with Shell, H.E. 60 lb., “SAP” No. 2 Mk Ihead)
4x 14,5 cm pansarsprängraket m/49A & B HEAT-rocket (Bofors 10.3 cm rocket with 14,5 cm HEAT head)
4x 15 cm sprängraket m/51A & B HE-rocket (Bofors 10.3 cm rocket with 15 cm HE head)
2x 18 cm halvpansarraket m/49A & B APHE-rocket (Bofors 18 cm rocket with 18 cm APHE head. At the start used primarily against ships but in the end against basically everything else.)
Bombs
Bomb bay
1228 kg max
10x 50 kg minbomb m/37 medium-capacity/general-purpose bombs
10x 50 kg sprängbomb m/42 fragmentation bombs
10x 50 kg Lysbomb m/32 flare bombs
10x 50 kg Bombkapsel m/43 cluster bombs (holds 2x 12 kg sprängbomb m/39G fragmentation bombs & 1x 12 kg sprängbomb m/37 fragmentation bomb or 3x 6 kg brandbomb m/39 incendiary bombs)
10x 50 kg Övningsbomb m/40 practise bombs
10x 8 kg övningsbomb m/40 practise bombs (addon mountings needed)
3x 250 kg minbomb m/37 medium-capacity/general-purpose bomb (central fuze with bent fins)
3x 250 kg minbomb m/40 medium-capacity/general-purpose bomb (central fuze with straight fins)
3x 250 kg minbomb m/50 medium-capacity/general-purpose bomb (nose & central fuze with straight fins)
2x 500 kg minbomb m/41 medium-capacity/general-purpose bomb (2 central fuzes with straight fins)
2x 600 kg minbomb m/50 medium-capacity/general-purpose bomb (nose fuze & 2 central fuzes with straight fins)
Inner wings
472 kg max
8x 50 kg minbomb m/37 medium-capacity/general-purpose bombs
8x 50 kg sprängbomb m/42 fragmentation bombs
8x 50 kg Brandbomb m/42 incendiary bombs
8x 50 kg Lysbomb m/32 flare bombs
8x 50 kg Bombkapsel m/43 cluster bombs (holds 2x 12 kg sprängbomb m/39G fragmentation bombs
&
1x 12 kg sprängbomb m/37 fragmentation bomb or 3x 6 kg brandbomb m/39 incendiary bombs)
