knock ? engine

A friend of mine has described an interesting model engine that uses air and has a ball bearing type valve - not sure about spelling of knock !

I have a pulse jet built many moons ago from plans in the model engine book - the Brauner design - have never got it to run . Is there anyone who could look at it please? based near Carlisle

Yes,co2 engines for very lightweight model aircraft operate on this principle, the piston has a small peg on its crown which as the engine turns through TDC the peg lifts the ball briefly and releases a small charge of gas which expands, pushing the piston down and is exhausted at the bottom of the stroke. Most of them will run in both directions, Gasparin is one brand, Czech made.

Trevor

Stan Bray in his book "Making Model Steam Engines" shows drawings for a Clapper engine called "Clarence" this is a steam/compressed air engine using a ball bearing valve lifted by a pin in the top of the piston. Hope this helps JC

David, I too made (probably) the same engine. I got it to run a couple of times - once on cup final day which brought the neighbours out during the match. I ran it on petrol, with the aid of a blow lamp and compressor. Difficult to start and latterly found out that the radius of the washer behind the petal valve was all wrong. I need some new petals and will need to find someone who could laser cut some from different thicknesses of steel shim. In hindsight, I think that a shop vacuum cleaner would be better used as a blower to get the initial start. Take my advice and use ear mufflers -they are very LOUD - - - LOUD ! - ! - ! - !

You are not too local to me as we are in France !
Good luck BobH