Saab 18

Sweden (1944)
Bomber – 245 Built

The Saab 18 is another example of Sweden’s efforts to produce an aircraft to safeguard its neutrality, considering that the same War and international political context prompted the Scandinavian nation to do so. Only that this plane was not devised to keep the skies of Sweden, but rather to protect the national territory from the air. Curiously, when WWII started, the Saab B 17 was given priority at the earlier stages of the war, as a dive bomber was considered more necessary than a light/medium bomber. This plane gave also important contributions to the development of the Swedish aeronautic and military industry, contributing in the development of ejection seats and of air-to-surface (or AGM) missiles; more specifically, anti-ship missiles. Despite being required to maintain Sweden’s neutrality and protect its territory, it entered in service in 1944, quite late to address the threat from Germany but ready to address the threat from the East and to serve at the early days of the Cold War, with distinction. It became also the standard bomber of the Flygvapnet.

The Saab B 18 is a light bomber and reconnaissance plane with three seats, two engines and a double tail, with a design similar to that of the Junkers Ju 86 and the Dornier Do 17 with the rounded shape of the vertical stabilizers. Or simply the very characteristic shape of double tail and double engine bombers of the era: this is, the cockpit placed at the frontal section of the plane and with the bow being made entirely of glass (normally the place of the bomber), and the cockpit being of a glazed offset type with the pilot and navigator. The wing has a trapezoid shape, being a straight leading edge type with the rear part being instead angled.

The Saab B 18 was initially intended to be powered by British-made Bristol Taurus engines. But it received in the end two types of engines during its career as the Taurus engines weren’t available, powered instead with two Pratt & Whitney R-1830 Twin Wasp radial engines of 1065 hp (the Saab J 21 had priority in receiving the Daimler Benz engines). Posterior versions received new powerplants as the Pratt & Whitney were deemed insufficient, hence receiving 2 Daimler Benz DB 605 of 1475 hp, enabling the plane to reach speeds of up to 570 km/h (357 mph), and making of the B 18 one of the fastest light bombers producing during the war. The powerplant was not the only modification the B 18 suffered during its service with the Flygvapnet, as the initial configuration of armament of 3 x 13,2 mm machine guns was changed to a set of one 7,92mm gun and 2 X 13,2mm machine guns (B 18B). Another re-configuration was the instalment of 2 X 20mm cannons and a 57mm gun (T 18B), along with rockets instead of bombs. Noteworthy to point out that the B 18 could carry up to 1,000 kg of bombs in the compartment and 8 x 50 kg bombs at the wings. As reconnaissance and torpedo-bomber variants were developed (though the last one was never put into service), the versatility and adaptability of the B 18 was made evident, at the point of being the platform for testing the Rb 302 anti-ship missiles. The crew was also modified, as following versions needed only two crewmen as rockets were introduced, suppressing the bomber.

Both versions (B 18B and T 18B) received another modification of armament in the 50’s, as they were fitted with rocket launchers allowing a maximum of 4 rockets on each wing, and even another rocket launcher allowing 2 or 4 rockets under the nose. The bomb sight was also equipped with an automatic reflex sight for rocket firing. This conversion meant that the B18B and the T18B would have increased – and more specialized – attack roles. Also, both the B 18B and the T 18B received ejection seats, maximizing the safety of the crew operating with these air assets. In addition, some B18 B units were fitted with two radars (a radar altimeter PH-10 and a search radar PS-18/A, which was a US Navy AN/APS-4 naval radar) for target designation and identification.

This airplane was purposed at replacing the Junkers Ju 86 in service with the Swedish Air Force back then, basing the requirement for a fast bomber with a crew of three. This was later on changed to a bomber having a crew of 3, a bomb payload of up to 750 kg (1653,46 lb), capable of reaching speeds of 500 km/h (310,68 mph) and to be used as a long-range reconnaissance, torpedo-bomber and heavy fighter. The fact that the B 18 ended in serving with the Flygvapnet was a sheer product of luck, as the competition’s design (the GV8 proposed by the competing AB Götaverken) was capable of meeting the requirements. Yet its costs and the departure of Götaverken’s chief designer resulted in Saab awarding the contract in 1938. As development began, many Americans reportedly took part in the design and development process, resulting in the B 18 having some “American traits” in the design. As a result, the B 18 development had a Swedish and an American chief designer: Frid Wänström and Carl Haddon, respectively.

The development process was delayed by two factors explaining the reasons of the Saab B 18 entering in service relatively late: first, the abovementioned shifting in priorities once the war started, with the Saab B 17 dive bomber receiving priority over the Saab B 18. And second, a change in requirements from a light bomber to a medium bomber, which ended in increasing the development time. The first flight took place in 1942, entering in service in 1944 with two initial versions: the B 18A bomber and the S 18A reconnaissance versions. A torpedo-bomber and later attack plane (T 18B), and a dive bomber (B 18B) were developed, receiving ejection seats.

After WWII and in the wake of the Cold War, the B 18B had a very interesting career, as the increase of the Soviet threat asked for reconnaissance missions; in 1945 and 1946 the B18 B was used to reach the Baltic coast and take pictures of every Soviet vessel, meeting Soviet fighters almost every time.

244 units were produced with the Flygvapnet being the sole operator until 1959, year in which the Saab 32 Lansen replaced the B 18: 62 units of the B 18A, 120 units of the B 18B, and 62 units off the T 18B were built. A single surviving airframe is displayed at the Flygvapenmuseum.

Design

The design of the B 18 is very typical of the pre-WWII double-tail light or medium bombers, having some interesting features despite its conventional sight at first glance. The B 18 is a straight leading edge wing airplane, with the engines placed at the first half of the wings. The fuselage was entirely made of metal, with fabric covering the control surfaces, and having the armor being integrally part of the structure.

The most remarkable areas are the canopy, the bow section, and the rear horizontal stabilizers, connecting the two vertical stabilizers with the main airframe. Regarding the canopy and bow section, the canopy is not placed at the longitudinal middle of the plane as it is normally placed, being instead an offset type at the left side. There, the pilot and the navigator were stationed, with the navigator seat being placed backwards. In addition, the bow section had a glazed tip where the bomber was stationed. Reportedly, such scheme improved the visibility for the pilot. The nose of the T 18B version was slightly modified. And the bow inferior section is not entirely straight, having instead an undernose gondola right before the wing-roots. The landing gear was of classic configuration, with the frontal landing gears retracting into the engine gondolas, while the small rear landing gear was placed at the stern of the bomber, right before the horizontal and vertical stabilizers area. In turn, the horizontal stabilizers are of a ‘butterfly shape’, having at the tips the two horizontal stabilizers; the rudders occupied the whole posterior area of the tails. The shape of the vertical stabilizers is of an isosceles trapezoid.

The wing is a mid-wing (cantilever) leading edge wing, with a shape of a right trapezoid and where the two engines are installed, along with the main fuel tanks. In some versions, there was a gun or a cannon installed at one of the wing-roots. The engines, depending of the version, were either a couple of Pratt & Whitney R-1830 Twin Wasp radial engines or a couple of licensed-built Daimler Benz DB 605 liquid cooled inline V-inverted engines. Depending of the installed engines, the air intake might be located below the engine gondola or above the engine gondola. Normally the earlier versions of the B 18 can be identifying by the intakes placed above the engine gondola. The Daimler Benz engine gave the B 18 a quite remarkable speed for a plane of its type back then, being among the fast ones with speeds of 575 km/h (357 mph). Such speed would provide an advantage for attack and reconnaissance missions. Reportedly, the T 18B version could reach speeds of up to 600 km/h (372,82 mph). The propellers of the B 18 where a three-bladed type.

The armament configuration also varied from version to version. The initial configuration was of 3 x 13,2mm machine guns, one firing forwards at the wing root, another firing also forwards at the nose, and another at the rear. This set was then changed for a set of one wing root 7,62mm machine gun and two 13,2mm guns, and then it was changed for a set of a front-firing 57mm Bofors gun at the undernose gondola and 2 x 20mm guns. The B 18 could carry up to 1,000 kg (2,200 lb) bomb and the bombs compartment and up to 8 x 50 kg (110 lb) bombs at the wings. This type of offensive armament was also changed, as it was first modified to carry a torpedo, which never came to be operational, and then it carried up to eight air-to-surface rockets. The B 18 was also used to test the Rb 302 anti-ship missile. The reconnaissance version was fitted with various cameras to perform its mission, along with a radar.

The B 18 was among the first planes in receiving ejection seats, as its high attrition rate made the Flygvapnet to implement such measure for the sake of the crew’s safety. The fact that it had ejection seats and capacity to carry missiles, along with its speed and un-conventional design, makes the B 18 a very interesting design made by a neutral nation during WWII and the early Cold War.

A Versatile Guardian of the Swedish Land

The B 18, although entering quite late to have a remarkable role in defending Sweden’s neutrality as WWII unfolded, it became a very valuable asset for the Nordic nation at the last stage of the war, when the Soviet Union became stronger and advanced towards the West, with the Cold War highlighting the threat it posed to Sweden. Not only its speed and considerable armament made the B 18 an air asset to be reckoned with, but also its versatility and adaptability, let alone its flexibility. The design allowed the installation of new engines that increased the speed of the B 18, as well as a change of armament while in service, at the point of serving as a test bed for one of the earlier anti-ship missiles, the Rb 302. These modifications allowed the B 18 to become very effective bomber and ground-attack planes, and even to serve as a reconnaissance plane capable of approaching or even penetrating Soviet airspace for its missions, facing quite often the Soviet fighters.

Striking at Speed

One of the characteristics that made the B 18 an airplane to be reckoned with was beyond any doubt its speed, especially after the Daimler Benz 305. The B 18B could reach speed of 570 km/h (357 mph), and the T 18B, the most powerful version in terms of firepower, could reach speeds of up to 600 km/h (372,82 mph). This was an advantage when it came to perform bombing or strike attacks with rockets, as the B 18 could have hit any advancing enemy ground forces formation with hit-and-run tactics or simply by direct strikes with devastating effects. Curiously, the S 18A was the slowest version, with speeds of up to 465 km/h being the maximum speed; this can be explained by the fact it was powered by the previous Pratt & Whitney engines, as the S 18A was a direct modification from the B 18A, which was (under)powered by such engines. Nevertheless, as the powerplants were enhanced, the B 18 became a very fast medium bomber. And it could have posed a serious threat to naval surface units approaching the Swedish coast.

Variants of the Saab B 18

18A – Two prototypes powered by Pratt & Whitney R-1830 Twin Wasp engines of 1065 hp.
B 18A – This version became the first series version of the B 18, powered with the abovementioned Pratt & Whitney engines. Armed with 3 x 13,2 mm machine guns and up to 1400 kg (3086.47 lbs). 55 units were reportedly converted into the S 18A reconnaissance version in 146-47. 62 units delivered.
S 18A – A modified version of the B 18A for reconnaissance purposes, replacing the Caproni Ca 313 (S16) reconnaissance plane in service back then. It was fitted with a varied array of cameras: 3 high-altitude 10/92 and 5/25 cm cameras, 1 panoramic 10/105 cm camera and a 13/30 cm night camera. This version was also fitted with a PS-18A (An American-made AN/APS-4) maritime surveillance radar, with 36 units having this radar installed in pods under the nose, and serving as maritime reconnaissance airplanes.
Saab 18B – A single prototype powered with the Daimler Benz DB 605B.
B 18B – A dive bomber version powered by the new Daimler Benz DB 605B of 1475 hp engines. It was later on modified to carry up to 8 air-to-surface rockets, becoming an attack plane. Armed with a 13 mm machine gun and a 20 mm gun plus the 1400 kg (3086.47 lbs) payload of bombs, and later on the 8 air-to-surface rockets. A dive bomb sight m/42 developed by Saab engineer Erik Wilkenson maximized its attack capabilities. Reportedly, some B 18B received a PS-18A radar. This version received ejection seats, and had the crew modified, reducing it to two (pilot and navigator/radio operator). 120 units delivered.
T 18B – A projected torpedo-bomber to serve as an anti-ship asset, it ended in being a ground-attack plane thus receiving an armament of a 13mm machine gun, 2 x 20mm guns and a 57mm Bofors cannon at the undernose gondola, receiving later on air-to-surface rockets. This version also received ejection seats. 62 units delivered.

Operators

Sweden
The Flygvapnet was the sole operator of the B 18, which entered in service in 1944 with 62 units of the B 18A model, followed shortly by 120 units of the B 18B that were initially purposed as dive bombers, developed later on into the T 18B with 62 units, which served as a ground-attack plane. The T 18B, in turn, was initially purposed to be a torpedo-bomber, but given problems with the new payload, received instead rockets hence serving as attacker. Some airframes were modified to be the S 18A reconnaissance plane, performing reconnaissance missions off the Soviet Baltic coast in the aftermath of WWII. It remained in service until 1958, year in which the Saab 32 Lansen replaced the B 18. It was used for testing the Rb 302 anti-ship missiles. The B 18B operated in 4 squadrons from 1944 to 1958: F1 Västerås, F7 Såtenäs, F14 Halmstad, and F17 Kallinge. The T 18B torpedo-bomber/attack aircraft operated also in the F17 Kallinge from 1948 to 1958. The S 18A operated in three squadrons in the same perios of time: F3 Malmen, F11 Nyköping and F 21 Luleå. A single B 18B recovered from a lake remains as a museum exhibition.

Specifications (B-18B)
Length	13.23m / 43ft 5in
Wingspan	17m / 56ft 9in
Height	4.35m / 14ft / 3in
Wing Area	43.75m2 / 470.92 ft2
Engine	2 X Daimler Benz DB 605 of 1475hp (some were licensed-built versions made by Svenska flygmotor AB).
Maximum Take-Off Weight	8800kg / 19,401 lb
Empty Weight	6100 kg (13,448 lb)
Loaded Weight	8140 kg (17,948 lb) (B 18A)
Maximum Speed	570Km/h / 357 mph
Range	2600 km /1,616 miles
Maximum Service Ceiling	9800m / 32,150ft
Crew	3 (2 in the T-18B)
Armament	A 13mm machine gun; 20mm cannon A 13mm machine gun; 2x 20mm cannon; a 57mm gun (T 18B) Up to 1400kg of bombs and rockets (the T18 B was intended to carry a torpedo or a mine, but it ended in having a payload of rockets)