Ion Mk 20 (oz15774)

About this Plan

Ion MK.20. Free flight sport model. Wingspan 33.6 in, for 0.46 to 0.8 cc engines.

Quote: "ION Mk.20. Introduction and Development: The first prototype of the Ion, designated the 'Ionosphere' Mk.1, flew more than seven years ago. It was of pusher configuration and powered by a Mills 0.75 cc. The Mk.2 was a tandem layout powered by a 'K' Falcon 2 cc and the Mills 0.75. The Mk.3 was powered by the D-C 350 diesel, and the Mk.4 by an Allbon Arrow glow plug motor. These were both tractors as were the Mk.5 and 6, which were powered by the D-C 350 diesel and Dooling 29 racing engine respectively, and had many successful flights on Fairlop Aerodrome in 1950. The Mk.7 was a tandem, powered by a PB Elfin 2.49 cc and a D-C 350, and was the first 'Ionosphere' to be fitted with radio control.

The Mk.8 which was fitted with engines ranging from the Ace 0.5 cc to the ED Bee was made available to the public through the Model Aircraft Plans Service in July, 1953. The Mk.9, powered by an Elfin .50 and Allbon Dart in tandem, had many flights on Epsom Downs in 1953. The Mk. 10 was powered by an Allbon Javelin 1.5 cc and the Mk. 11, Oliver Tiger 2.5 cc powered Ionosphere, broke the Power Driven Tailless Record on Epsom Downs in March, 1954.

The Mk.12 was once again of tandem layout powered by a Miles 5 c.c. and Amco BB 35. It was fitted with multi-control radio gear. The Mk. 13 was a light weight, and broke the National Light Weight Record in July, 1954, on Epsom Downs. The power unit was the E.D. 0.46 c.c. The Mk. 14 fitted with an A-M 2.5 c.c. won the Open Tailless competi-tion at Radlett Aerodrome in 1954 and again in 1956.

In 1956 the name of the flying wing series was changed to 'Ion' due to the fact that the leading edges which up to that time had been straight, were changed to crescent and double delta type. The Mk.16 broke the RAF Class B Open Power Free Flight Record, and the RAF Open Tailless Record in June 1955 at Marlborough, powered by two Elfin Clack Valve BB 1.49 cc engines; and the Mk.17 was a similar machine powered by two ED 2.46 cc diesels.

In 1956 the first true crescent winged Ion was produced, and extensively tested at Bramcote aerodrome near Coventry. This was the Mk.18, and was powered by the Frog 80 diesel. The Mk. 9 was a similar machine powered by the Allbon Super Merlin. Lastly the Ion Mk.20 has in common with all its predecessors been extremely thoroughly tested, often in the worst conditions of wind and rain on deserted aerodromes. It has been tested with engines of various types, but is especially suited to the Frog '80' diesel.

Like every other Ion and Ionosphere the Mk. 20, the last of the series, is capable of ROG flights which are spectacular but quite safe. The Ion takes a long fast run before taking to the air followed by a steep climb, and stable circling flight pattern. We should like to say that from the first Ionosphere Mk.1 to the production Ion Mk. 20, we have never had a poor performer, and the above is a true record of the development of the Ion.

CONSTRUCTION: Firstly cover the plan with a piece of wax paper (the inner wrapping of a cereal packet is suitable) this will both protect and prevent the framework sticking to it.

Cut out the ribs R1 to R8, taking care to cut the notches obliquely so as to allow for the spars. Notch the 3/4 x 1/4 trailing edges, and pin them in position over the plan; at the same time packing up their outer edges by 1/16, so as to produce slight reflex. Pin the lower spars over the plan, and cement the ribs in position over them. The root ribs R1 are canted towards the wing tips by 1/2° from the vertical to obtain 0.156 in dihedral at each tip..."

Direct submission to Outerzone.

Quote: "Hi Mary/Steve, please find attached the Plan, Instructions, Printwood and Kit content image for Ion, a lovely 33.6" wingspan free flight flying wing design by Peter (O.F.W.) Fisher. This was one for the first two kits that were supplied when Peter formed his company Performance Kits in 1957. The other kit supplied at the same time was the Apex. I have also included some pictures of the RC Ion that I recently built. It's a lovely model that flies really well, a real floater! I did film an Ion build series on my YouTube channel - here's a link to the playlist: https://www.youtube.com/playlist?list=PLGILJsUw3dvQ_7RaVZutDej6IVZ4zC3AV
All the best, Mark"

Supplementary file notes

Instructions.
Printwood.

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