The K5 was designed at the end of 1962 with the twin objectives of providing a competitive hillclimb car costing under £800, and at the same time to investigate a new concept for Formula 1 design.
The aim, as in all racing car design, was to combine maximum useable power with minimum weight and also keep good handling characteristics. In order to keep the cost down the Royal Enfield 700cc vertical twin motorcycle engine was used. This developed 51bhp but weighted only 150lb complete with transmission. This was a typical twin cylinder British cycle engine in which both cylinders move up and down simultaneously, so the suspension must take account of the unbalanced forces.
The overall weight was chosen to be kept under 400lbs, which could be achieved using the monocoque shell as in the K1 if suitable aircraft specification material was employed. The materials used were hiduminium, high tensile steel and titanium. As in the K1 the main structure was assembled in a jig, but in this case six elliptical hoop formers were used each made from 18swg high tensile steel, five channel section and one of "T" section. The 16swg hiduminium skin was riveted to this frame. Unlike the K1 there were no longitudinal members and the structure was made in two halves to permit removal of the jig. It was finally joined together in the middle by the "T" section former.
An opening was provided for the driver and the chassis was strengthened with extra panelling around his feet area and with titanium sheet around the rear engine bay area.
The second former at the front of the car suppoerted the front suspension mounted at a 3 degree castor angle. To keep the weight down a light tubular rear axle was used with a single inboard twin leading shoe brake drum next to the sprocket for the driving chain. There was no differential. The suspension mounting brackets were held apart by a 2" diameter 19swg cross tube with brackets off taking the coil oversprung telescopic dampers. The engine rear mounting bracket was also attached to this tube so that the weight was directly taken on the springs rather than the chassis skin. The suspension brackets had light weight equal length semi-trailing arms at the top and bottom to keep the wheels aligned.
The engine was set on flexible mountings and a thrust plate applied force to a ball bearing race on the centre of the solid rear axle keeping the axle and the gearbox forcibly separated. This kept the driving chain under tension whilst allowing for movement of the rear suspension which could "wind up" during a racing start, and also the engine vibrations.
Clearly a solid axle with no differential gear would not be ideal on cornering and the car, which also has rather short wheelbase and low weight, initially showed an alarming tendancy for the rear end to try to join the front. This was moderated by fitting Dunlop SP radial tyres at the rear, while keeping cross ply ones at the front.
The car was contested in hillclimb events at the start of the 1964 season. One driver was N.S. Slade. He had pursued a long sprint career with Rupert Instone's Martyr and later bought a Cooper Norton before getting the Killeen K5. The Martyr was a so called "Shelsley Special" (named after the famous hill climb at Shelsley Walsh which attracted much competition between specials builders) constructed around 1930. It was a GN based car with a Zöller blown 966cc vee twin J.A. Prestwich JAP engine producing over 100bhp with ear piercing volume. By the time Slade got it, it had independent front suspension, although the original front axle was from an older Frazer-Nash special car called The Terror built by Dick Nash. It was raced by Rupert Instone until around 1946. The Cooper MkIV announced in 1953 was a 500cc car using the Norton Manx engine which produced around 5bhp more than the equivalent JAP engine.
In 1973 Slade was managing director of Rycam engineering, of Sutton Coldfield who manufactured Killeen's Mirage K18.
See Culshaw and Horrobin The Complete Catalogue of British Cars  p407.
[photo of K5 on show stand, Classic and Sportscars ???]