OS 35s can throw big ends , theres a cruciform oil groove slot on front face , nylon ' T ' - like gudgoen cap , plugged into crankpin to space rod off backplate .
that said , ive worn a few out , though was useing ' any old fuel ' inc. " runnig in " which " we " later learnt had metal polish

in it .
Best a hours gentle use , 1/2 Hr on bench ( or cool air ) before you get carried away .

Id put one NEW in this , which was 54 span , 1.45 kilo . Had to toss the spinner & silencer for a few flights to get it airbourne , then it quickly freed off .
Hauls 55 Oz odd ( give or take a few ) authoritively . Nobler Size stuff .
used a . 20 venturie in the 30 S , & 35 to get a bit more swing . Use GOOD oil in any , 20 % castor 3 % synthetic , and there not nitro mad .
The Merco was ' the ' blitish stunt injun . Useually specified on 60s blitish plans . Warburton Designs , APS ' Mustunt ' etc etc . Said to run strong .
ST 35 S , Via the test , pulss good rpms on the 10 x 6 , which wot allovem like , or maybea 11 x 5 thinned wood , for call air and 65 ft lines .