Battle of the jet powered interdictors
The advent of jet technology offered performance far in excess of what propeller technology could deliver particularly at high altitude. This was especially important for bomber crews who wanted an aircraft that could fly faster and higher than any fighter aircraft that could intercept it. The concept had been proven by the superlative De Havilland Mosquito during the war and now the RAF wanted a jet powered replacement. This spurred the development of the English Electric Canberra which first flew on the 13th May 1949 and was soon ordered in to production. Entering squadron service on the 25th May 1951 the RAF was initially disappointed with their new mount as they had wanted a large four engined strategic bomber. All criticism quickly evaporated however as the RAF’s first jet bomber proved to be a superb design with outstanding high altitude performance. During the course of its career the aircraft undertook a plethora of roles ranging from bomber, interdictor, photographic reconnaissance, electronic warfare training and signals reconnaissance to name but a few. In fact the airframe would prove so useful that the PR.9 high altitude reconnaissance variant remained in service until 2006!
The Soviet air force too knew of the potential the jet engine offered but were not as successful in the development of the technology as engineers in Britain. At first they had to make do with captured German technology but then as a gesture of good faith the British offered the Soviets the Rolls-Royce Nene engine. This catapulted Soviet jet technology forward but as relations between east and west quickly soured the Soviets were forced to develop their own engine based on the Nene and this became the Klimov VK-1. Soviet engineers were instructed to build a twin engined tactical bomber powered by the VK-1 and the result was the Il-28 (NATO codename “Beagle”). Often called the “Soviet Canberra” the Il-28 actually flew a year earlier than the RAF aircraft but despite its revolutionary powerplant it was very much a traditional Soviet tactical bomber design featuring a cigar shaped fuselage with the pilot sitting in a fighter style cockpit and straight wings.
Both these aircraft catapulted their respective air arms in to the jet bomber age but the traditional medium bomber concept (streams of bombers in formation to attack a target from around 15,000ft) soon became impossible due to increasingly powerful defences. A role that emerged in the Second World War was that of the interdictor whose job was to attack targets far behind enemy lines that would directly affect the battlefield where the troops were fighting. These primarily concerned lines of communication and supply. Often these aircraft were large twin engined types as these were the only aircraft with the range and hitting power for the job and both the Canberra and Il-28 aircraft were adapted to the role but which was better?
The Canberra B(I).6 was a development of the B.6 which was a traditional medium level bomber. The bracketed “I” in the designation denoted that it had an interdictor role meaning it was intended to attack tactical targets that have a direct influence on the battlefield e.g bridges, road convoys, storage centres, etc. It was still capable of operating as a traditional level bomber and trials were conducted in an anti-shipping role although it never undertook this tasking operationally.
The Il-28 was the basic bomber version of the “Beagle” and was designed for fast attacks on enemy positions although like the Canberra it was never really intended for use as a strategic bomber. Following Soviet doctrine the Il-28 was designed to directly support the army and so was used as an interdictor from the start.
The Canberra B(I).6 was powered by a pair Rolls-Royce Avon R.A.7 Mk.109 turbojets that each developed 7,400lbs of thrust. These engines and large wing area gave the aircraft its superb high altitude performance with USAF U-2 pilots who flew the PR.9 version describing it as the more stable aircraft above 50,000ft. The B(I).6 variant has a service ceiling of around 48,000ft but even at this altitude the aircraft is no slouch being able to achieve speeds up to 580mph. To put this in to perspective the main fighter opposition the aircraft could expect to face in the early 1950s, the legendary MiG-15 “Fagot”, is almost identical in performance meaning that intercepting the Canberra would be extremely difficult since it lacks the necessary speed to overtake it. Combat radius was in the region of 810 miles depending on bombload and altitude.
The Il-28 featured two VK-1 turbojets mounted in large nacelles on the wing that also featured the the main undercarriage. These engines gave the aircraft a top speed of 560mph when operating at an altitude of 14,000ft but this deteriorated as the altitude increased. This meant that the Canberra was significantly faster at higher altitudes but on the flipside the Il-28 was faster at lower levels. The smaller surface area of the Il-28’s wing and and the lack of high altitude power in the VK-1s meant that the aircraft had a service ceiling of only 40,000ft. All this reflects how the Soviets planned to use their aircraft; low to medium level supporting the army. The Il-28 had shorter “legs” than the Canberra however with a combat radius in the region of 600 miles; again this was dependent on bombload and altitude both of which affected performance.
To make it as light as possible the original Canberra lacked any gun armament instead using its speed and altitude as its main defence. In the interdictor role however it was deemed that guns would be needed for offensive purposes e.g. strafing convoys of trucks. Therefore a ventral gun pack was developed equipped with a quartet of 20mm Hispano Mk.V cannons in a similar arrangement to that featured on the Bristol Blenheim IVF of World War II vintage. The gun pack was fitted in the rear half of the bomb bay thus reducing the number of bombs that could be carried internally although the space the bomb bay offered meant each gun had a rather generous 500 rounds available to it.
The ventral gun pack was not a permanent fixture and could be removed as and when it was required for the Canberra to carry more bombs. For when the aircraft did carry the guns a pair of underwing pylons could be utilized to make up the shortfall in bombs. Royal Australian Air Force Canberras operating on short range missions over Vietnam went a step further and strapped bombs to the wingtips in place of the long range fuel tank! The Canberra B(I).6 had a total bombload of 8,000lbs and this could be carried in a variety of bomb configurations. The B(I).6 had a tactical nuclear role as well being able to deliver a variety of US and British nuclear weapons most importantly the WE.177A. All nuclear weapons were carried internally.
The underwing pylons were also used to carry a variety of other weapons. Typically these would consist of rocket pods comprising of either 37 2-inch (51 mm) rockets or 2 Matra rocket pods with 18 SNEB 68 mm rockets. A handful of B.16s (upgraded B.6) were wired to carry the Nord AS.30 missile for stand off air to ground attack as well as, potentially, anti-ship operations.
Unlike the Canberra the Il-28 was designed from the outset to have gun armament for use in the strafing role and to that end was fitted with two NR-23 23mm cannons in the nose which individually have a longer range and hitting power than the Canberra’s Hispano Mk.V. The Soviets knew their bomber lacked speed and altitude to escape interception and so it was going to have to defend itself. Therefore the Il-28 featured another pair of NR-23s in a powered tail turret to discourage any fighters from getting too close. The forward guns had 100 rounds each while the tail gun had 250 rounds each.
Maximum internal bombload for the Il-28 was just 6,600lbs although operationally the figure rarely exceeded 2,200lbs. Bombloads larger than this incurred a hefty penalty on performance to such an extent that often, when a bombload closer to its maximum was required, the tail turret would be removed. It also didn’t help that the Il-28 was limited by the dimensions of the bombs it carried because of the small size of the bomb bay.
Other weapons made available to sub-variants of the Il-28 included the ability to launch a 1,380lb torpedo although this variant died a quick death as Soviet Naval Aviation realized that such weapons air-launched were now obsolete. Nevertheless the Chinese did pursue the technology with their Il-28s and the subsequent locally produced H-5 variant of the “Beagle”. The basic Il-28 was incapable of carrying a nuclear weapon in the 1950s due to the sheer size of early Soviet weapons however a dedicated nuclear bomber version was built later which featured a bulged bomb bay.
The Canberra was never meant to be a mud mover instead it was an aircraft optimised for the high altitude role and it is in this capacity it is best remembered. Nevertheless it adapted well to almost every role it was given and remained a sublime aircraft to fly at low to medium level. As an interdiction aircraft it carried a useful bombload and, as the Royal Australian Air Force proved dramatically in Vietnam, could deliver its weapons with a high degree of accuracy. Simplicity was the key to its success being a nuts-and-bolts type meaning provided it could lift it off the ground the Canberra could carry pretty much any equipment or weapon that was asked of it. The B(I).6’s guns gave the aircraft a powerful punch in strafing attacks but as the Indian Air Force found out with their Canberras the size of the aircraft made it a big target to ground fire.
The Il-28 has also enjoyed a long service life (longer than the Canberra if you count the Chinese built H-5s still in service with North Korea) but has not proven as adaptable. Aside from avionic improvements many of the Chinese H-5s that were still operational in the 1990s were hardly anymore capable than the original 1950s vintage aircraft. Il-28 combat experience has been quite disastrous in the hands of third world air forces such as Syria. Nevertheless during the Six Day War the Israelis considered them a high priority target and made great efforts to destroy them on the ground. Interestingly the Pakistani Air Force flew the Chinese built H-5 version alongside US supplied B-57s (a license built version of the Canberra fitted with a tandem cockpit) against the Indian Air Force who flew the Canberra. The Pakistani pilots wholeheartedly agreed that the B-57 was superior and returned the H-5s.
The Pakistani opinion largely sums up the two aircraft. The Canberra has a wider array of weapons available to it, can carry more weapons further and transit/escape at higher altitudes with speeds comparable to a fighter. The only things the Il-28 has in its favour is that at low to medium level it is faster than the Canberra (although in this flight regieme both aircraft are extremely vulnerable to interception) and its smaller dimensions make it a much harder target to hit from the ground.