About the Model:

OBERURSEL UR-2 ROTARY ENGINE - 1/12 SCALE
Designed and built by MIKE DENNIS © May 2004
Member HTMC RMG ISM 0328 -
Co-founder of the Half Inch Systems Group 2002

Introduction

The Oberursel UR-2 rotary engine was an exact copy of the French LeRhone 9J 110-horse power engine. The engine shown above is one of the very few still in existence and is shown for comparison with the model which was made by reference to this photograph and others, plus a copy of the official Le Rhone 9J Engine Manual which is still available.

Brief Details - 1 1/2 Scale UR-2 Engine

The model runs at 1040 R.P.M. on 12 Volts DC and the drive is provided by an MFA 941D41 Electric motor via a 13/25T reduction gear. The engine is fitted with a Truflite 9"x 6" wooden scale propellor reduced to 8.5" with the tips radiused and blended.

Jigs, methods of approach to parts and sequence of operation are all important factors to be considered when building any model Aero engine to such a small size. This is due to the handling at each stage of part manufacture. Each Cylinder comprises 7 parts. The main body, Valve rocker bearing, Valve rocker shaft, rocker pin, crank, tappet rod and the intake and these are all accurately machined and drilled using specially made jigs. The cylinder is shown with the valve rocker mechanism and plug fitted and was assembled for the photograph - The rocker assembly cannot be finally fitted until the cylinder is bolted to the crank case by 3/4 " length Allen bolts with the heads turned down to Ø 6mm. The push rod and crank is then fitted and the intakes are fitted last using a CyanoAcrylate adhesive (Super Glue) or Epoxy Resin Adhesive (Araldite)