R
- R.E.P.
- Radne Motor AB
- Rapp-Motorenwerke GmbH — Germany
- Rasmussen
- Rausenberger
- RBVZ
- Reaction Motors — U.S.
- Rearwin
- Rectimo
- Redrup
- Regnier
- Reid Gas Engine Co — U.S.
- Renault — France
- RFB
- Rheinmetall-Borsig
- Ricardo
- Ricardo-Halford — UK
- Righter — U.S.
- Roberts
- Rockwell - U.S.
- Rocky Mountain
- Rolls-Royce Limited — UK
- Rolls-Royce North America — U.S.
- Rolls-Royce plc — UK
- Rolls-Royce/SNECMA
- Rolls-Royce/Turbomeca
- Rotax — Austria
- Rotec Engineering — Australia
- RotorWay International - U.S.
- Rover Company
- Royal Aircraft Factory - UK
- RRJAEL
- Rumpler
- Ryan-Siemens – (Ryan Aeronautical Corp)
Read more about this topic: List Of Aircraft Engine Manufacturers