#1 SH 37 Bench Runs

Electric power is currently dominating model aviation. However, there are still those among us who still favor IC as a viable power source. Unfortunately, the number of manufacturers has almost vanished for 'sport' engines. There are still producers of 'completion' engines, but these are quite expensive and a bit prohibitive for most of us. For control-line fliers this is even more true. In an attempt to find a useful engine for the '35-40' size of CL models, I acquired a SH .37 from MikeGoesFlying.com. This begins a series of short videos detailing development of this engine for CL stunt.
I began by machining a Super Tigre style 'true venturi' using Delrin. The venturi throat was cut with a #20 drill (.161") yielding an effective choke area of 11.94 sq mm. This falls in the range recommended by Claus Maikis. A Super Tigre style NVA was modified to fit.
Due to my preference for high oil concentration, an extra .2mm head shim was added. The initial bench runs were performed with 5% nitro, 22% oil (1/2 castor), a hot glow plug, and a 10x4 Graupner prop.
Following the bench runs, a 10.5x4.5 APC prop was mounted and the engine installed on an extended Tutor (51" span). The first flight follows on another video.
• #2 SH37 Flight Test 1 ...
In an attempt to minimize the CL conversion cost, another 'true venturi' was machined from Aluminum and the main jet NVA from the supplied throttle was used to control fuel mixture. Further videos follow.
Hope you find this useful.

[@jannovak2234]

Hi dear sir .. thank you for this video , I am looking for motor for Sig Kobra ,, size 35 .. please tell me How it runs with RC carburetor .,, is it strong motor ? similar to os 35 Ax or ASP ... thanks for the reply,, Jan

[@frederickkrueger783]

Jan, I did not try the R/C throttle. The quality of the this engine is quite good. The throttle mechanism appears well made so I would expect it to work well. Yes it is quite powerful and smooth running.