Past Talks : September 2021

“Development of the F86 Sabre” by Rod Dean

Hands up all those who do not think the F86 Sabre is a rather handsome looking aircraft?  I think you dissenters and I could have an absorbing debate on this subject! There are many other equally appealing designs of course, but they were not the subject of today’s talk by Rod Dean. Rod Dean is a well-known speaker to SOFFAAM and his talks are always very varied and well informed.

To set the scene Rod opened the talk with film taken from inside and outside of the cockpit of him flying the F86A Sabre at a Duxford air display. It is the only F86A still flying and sadly for us in the UK it was sold back to the USA in 2014.

The origins of the F86 date back to the 1940s, when the USAAF (United States Army Air Force) put out a requirement for a jet powered escort fighter. North American Aviation had an existing proven track record for producing very effective aircraft, including the Harvard (T-6 Texan) trainer, B25 Mitchell bomber and the P51 Mustang. Their response to this requirement was typical for the period and combined pretty much a modified fuselage with jet power to standard Mustang wings. The outcome was that its performance was little better than the Mustang, or more importantly its competitors.

North American was not alone in this approach as you will see from the Supermarine Attacker using Spiteful wings and retaining its tail-wheel undercarriage; the Russian Yak 3 became the Yak 15 with a jet engine (thanks to the generosity of the British Government) bolted below where the piston-engine was previously mounted – and still with its tail-wheel; Sweden converted the rear-mounted Daimler-Benz piston engine on the J21 to a DH Goblin jet engine and called it the J21R, and retained its already tricycle undercarriage. Each of these designs kept its straight wings.

If North American was to win this contract, it needed come up with something better, much better. The solution was derived from the swept wing technology developed by Germany in WW2, when the USA and Russia went to great lengths to get to know, find and ‘extract’ leading German scientists from the ruins and chaos at the war’s end. The great advantage of swept wings over straight wings is that it delays the effects of compressibility at high speeds – thus allowing the air to travel faster over swept wings.

Once again North American produced a distinctive and winning design in the F86 Sabre, which first flew on the 1st October 1947, followed very closely by the Russian Mig 15 on 30th December 1947. Both nations certainly moved fast and left Britain trailing with the straight winged Meteor, Vampire and Sea Hawk designs. We had to wait until 1951 to see the swept wing Hawker Hunter enter service with the RAF.

Unquestionably, the swept wing showed a distinct speed advantage over conventional straight wings and the F86 Sabre was a remarkably clean, smooth design, produced in large numbers in the USA, Canada and in Australia. Overall 9,860 F86 Sabres were built and it was operated by a large number of nations including the RAF as an interim until the Hunter entered service. Examples were still in service as chase-planes into the 1990s.

For an aircraft that did not appear to change much at all throughout its lifetime, there is a stunning number of variations, most barely visible to the untrained eye. Rod took us through the various model types and explained the differences. He also made the point that the design made interchangeability of components – wings in particular, relatively easy to the point that a ‘standard’ F86F, for example might not be quite so standard when you look at the detail and see that it has been retro-fitted with wings from a different model for one reason or another! Confused? – I was, Sabre wings are a complex subject and the permutations are best left to experts. It still looked good though didn’t it.

As American aircraft go, the cockpit was quite small and tight compared with the P51 Mustang, but all-round visibility was excellent. The instrument cluster had less logic to it than the standard UK aircraft at that time, but the six, excellent 0.5 calibre machine guns could be selected to fire just the upper guns, the lower guns, or whatever the pilot decided was the best combination. The engine was the General Electric J-47 (derived from UK technology) which emitted the US trademark black exhaust trail behind it, so distinctive on all American aircraft until pretty recent times. For ease of maintenance, the airframe split behind the wings enabling the complete tail section to be withdrawn to expose the engine. Good thinking. Likewise, from a pilot’s point of view there were no limits on extending the air brakes, which were very effective.

As ever in life, not everything was perfect. It was very thirsty, like all jets in the 1950s and North American shoe-horned fuel into every conceivable nook and cranny. In due course, drop tanks were introduced and in combat conditions they were the first source to be used so that they could be dropped leaving the aircraft in optimum fighting readiness to meet the foe.

The earlier Sabres had automatic leading-edge wing slats that popped out to improve handling at lower speeds. Some models had a 12” wing tip extension beyond the slats, while some models were not supplied with slats, but had them fitted later – do you get the confusing drift of wing variants?

A question always asked is how did the F86 Sabre compare with the Mig 15 in the Korean War? The Sabre typically had a 37ft wing span, with 6 x 0.5cal machine guns. The Mig 15 had a 33ft wing span plus one 37mm canon and two 23mm canon. The Sabre therefore had a good punch with lots of ammunition, whereas the Mig had a much greater punch, but with fewer rounds. In terms of performance the Sabre was better at lower levels, while the Mig was at its best at higher altitudes. It is said, and records claim that 10 Migs were lost for every Sabre lost. However, to balance this, the USA, after WW2, had more combat experience than Korean and Chinese pilots, although Russian pilots were a different kettle of fish entirely.

A night fighter version was the F86D model with a very distinctive radar nose cone built into and above the engine intake. The radar was very advanced for its time and provided a great deal of automation for the pilot, including choosing the optimum time to fire the rockets, etc.. The F86D had no guns, just 2.75” unguided rockets.

Canada manufactured a version of the F86E under licence calling it the Mk2. A later Mk6 variant used the more powerful Canadian Orenda engine with 6,500lb thrust and was regarded by many as the best of all the Sabres. Canadian Sabres were used briefly by the RAF and also were bought by the USAAF. As an aside, Rod has always enjoyed aerobatics, but he was deeply impressed with the extremely close formation flying of the Canadian aerobatic team in their Sabres – which we watched on film. Over 1,800 in all were built in Canada.

Australia took an entirely different approach to their manufacture of the Sabre under licence. In the first instance it was fitted with two 30mm canon and redesigned to take the Rolls Royce Avon engine, which was more powerful and more modern than the J47. This enabled their Sabre to have commonality with the RR Avon powered Canberra bombers also in service. Sensible and simple? No, just like Britain putting the RR Spey engines in its Phantom aircraft, it became a nightmare of complexity. There were benefits, but they were submerged into the agony of making it all happen. 112 Sabres were built in Australia. A further 500+ Sabres were built by Italy and Japan between them.

All F86 variants had ejection seats from day one, although export models used Martin Baker seats in place of the US items. Likewise, although the F86A only had limited power assisted flying controls, while all later models were upgraded to fully powered controls.

Throughout the entire talk Rod illustrated each element he was referring to and the frequent film clips were a delight and real treat to watch. Thank you again Rod for a super Zoom talk on a subject that will always grab attention, but was even better through your presentation. Thank you also to the backroom team that made it happen for us. A very smooth and enjoyable talk.