This document is the instruction manual for the O.S. 91HZ-R speed version of a model engine developed expressly for 3D flights. The engine features an integrated Demand Regulator System (DRS) to ensure steady fuel supply during vigorous attitude changes and includes a new 61G carburetor with twin needles for independent mixture adjustment.
| Fuel Type Requirement | Helicopter use fuel with 10% to 30% nitromethane |
|---|---|
| Lubricant Requirement | At least 18% lubricant by volume |
| Glow Plug Type | O.S. No.8 |
A fuel containing 10% to 30% nitromethane is preferable for best throttle response.
The fuel must contain at least 18% lubricant by volume for consistent performance and long engine life.
The O.S. No.8 glow plug is supplied with the engine.