I recently purchased this engine, an Irvine 61R.  In its previous life it was used as a Free Flight engine with a .350 venturi which the owner kept.  Because it will likely be asked the engine as shown weighs 16oz -- for comparison my ST 60 weighs 12.5 oz.   I have not removed the head so I do not know what kind of head it has but it does have a flat top piston with an Dykes, L section ring.  the engine appears to be in great condition with little if any carbon build up internally.

My question is....Does anyone have experience with this engine as a Control Line engine?  If so, what size venturi do you use, what are the specifications of the plane it runs in?  What was the source of the venturi?  The original owner gave me some information but I want to follow that up here from your collective experience. 

Ive searched the Just Engines website and they do not list this engine.  Ive also tried to search for information on Irvine but it was apparently bought out a year or two ago.  Interestingly, from what Ive found OS Engines now owns the Irvine name.

Any help would be greatly appreciated.

Regards,
  Thomas

Randy,

I was asking as a general control line question, more along the lines of stunt and not what I would classify as aerobatics.  In my mind stunt and aerobatics are different.

I did find one use of this engine in control line.  It's in a scratch built Bob Hunt Saturn.  1.3 was added to the tail moment to help balance.  The engine runs on a Carbon pipe from Windy, 7% Nitro 50/50, fuel consumption is the same as his RoJett 61. I'm told its an easy to run well mannered engine.

Whether or not I use it in CL remains to be seen.  After talking to Just Engines in the UK, it seems that this 61R may have some collector value and it would be a shame to mark up this beautiful engine.

Regards,
  Thomas