Interesting stuff, folks.
The samolotypolskie-pl page lists Pidek JP.2B powerplants as modified 50 hp 4-cylinder Ariel motorcycle engines. That description eliminates the Ariel-badged BSA A10 2-cylinder. [1] So, the engines have to have been the old 998 cc 4-cylinder Ariel
Square Four Mark IIs.
The '
Squariel' was an odd design with paired 2x2 cylinders. It was produced until 1958 but the Mark II was a heavily revised derivative of a 1930 design. A stock
Square Four Mark II produced 40 hp @ 5,500 rpm in standard tune. However, the Healey brothers later tuned the engine to 50 hp @ 6,000 rpm. That 20% increase in power didn't occur until the 1970s ... but it does prove that such outputs were possible with a retuned '
Squariel'.
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https://silodrome.com/history-ariel-square-four/
The samolotypolskie-pl page claims that twin 100 hp aircraft engines - Lycoming or Continental - were planned replacements for the Pidek JP.2B. In other words, this was to be a prototype conversion for the proposed production type. But this conversion seems never to have happened. And that brings up the turbine-powered Pidek Pi-4.
Some sources claim that the Pi-4 was the JP.2B re-engined with turbines. But the last clipping by
@hesham makes clear that the Pi-4 airframe was revised compared with the original JP.2B (specifically in tailboom arrangement and undercarriage type). So, reply
#2 was in error - JP.2B was not another name for Pi-4.
That clipping also makes clear that, for testing, the Pi-4 was fitted with the 50 hp Ariel engines from the JP.2B. The turbine engines - of Pidek's original design - were not expected to appear "before the end of 1968". In the meantime, Joseph Pidek had incorporated as Pidek Industries & Co with an address on Lulu Island. So, the question is: Was the turbine engine ever completed? Or had Pidek over-extend himself?
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[1] Ariel-badged BSA A10 engines powered Ariel
Huntsman bikes which were produced until 1959. However, the A10 displaced only 646 cc and Jens' clipping clearly reads: "50 PS 1000 ccm Motorradmotoren".
