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Friday, November 17, 2017

Super Atom .99 Model Ignition Engine

 Famous American Model Engine Designer Ray Arden's 0.99 cubic inch spark ignition engine

 Original box  dating back to the early 1940's that contained the test engine.
 Specifications:
Bore 0.50 inches;
Stroke 0.50 inches;
Displacement 0.97 cubic inches;
Speed Range 250 - 17,500 RPM


 Test engine shown new in it's box.
 Front 3/4 view of the four variants of the engine shown above.
 Rear 3/4 view shown above.
 The most unique feature of this engine is the piston which incorporates a pressure activated valve to facilitate the flow of the combustion gases to and from the combustion chamber. This feature is explained later in a short video clip.



 Shown above is the side view of the oldest version of the engine with its circular exhaust ports. 

 Shown above are the elements of the external ignition system: high tension lead, coil, condenser and the low voltage hook-up leads.
 Shown above is a schematic drawing of the suggested wiring hook-ups for different applications: free flight, control line etc.

Another unique feature of this engine is the total absence of an needle valve assembly to control the fuel flow to the engine, instead there is a fixed jet and the mixture id regulated by a lever located beneath the crankcase.



Engine mounting setup for the first run of this new-old engine shown above.

The next two short video clips demonstrates the aspiration feature and running characteristics of this engine.




Monday, September 4, 2017

OS 48 4-C Surpass





I have several of these engines in my collection, at one time we were of the opinion that it should be the engine standard choice for my scale sport models.

This one was not running very well and a few flips of the propeller answered my question; the valve timing was off and would have to be reset before the next run.

I discovered this before: valve timing cannot be accomplished on surpass engines until the valve rockers and push-rods are removed are removed and the head bolts loosened, to allow the timing gear clear the cam follower. This is a very annoying reality with this design; since the timing operation is essentially a hit or miss task it usually requires several tries to engage the correct tooth; having to remove all those screws is most frustrating procedure indeed. 

As soon as the valve cover was removed we also discovered the valve gap was far too large (estimated at .090 - .120 inches): another reason why its performance was so poor.

Engine run after timing set-up and valve tappet clearance adjustment:



Watch another of my OS 48 4-C engines running after I had performed a rather unorthodox repair when it threw its connecting rod in flight and punched out the bottom of the crankcase.