JeffTaylor
Active Member
- Joined
- Apr 6, 2020
- Messages
- 40
I have begun a project to design and build my own axial cam internal combustion engine and I’m starting this thread to share my progress and hopefully generate interesting and helpful discussion. I’ve been following several engine-build threads at HBA and there are some very knowledgeable and experienced people here who may find this interesting. This is just for fun, a hobby project to improve my CAD skills and tinker with engines. I will build working models, but do not plan to make engines commercially.
Axial cam engines have advantages that make them appealing for aviation use. They can be relatively compact and low profile, allowing more streamlined cowlings. They turn slowly, the driveshaft turns at camshaft speed, providing lots of torque at low RPM, excellent for direct drive and large diameter propellers. They can have perfect balance, and with a power pulse every 30 degrees (for a 12 cyl engine), should run very smoothly. So why isn’t there an axial in every piston power plane? I don’t know. There clearly must be some flaws and difficulties in building these engines or we would have more working examples, but maybe these can be solved or worked around.
I have decided that the best way forward for me is to copy the “Dyna-Cam” engine basic design while modernizing where possible. There is just enough information available on the Dyna-Cam engine to convince me the basic concept has merit, but little enough information to avoid feeling like this has all been done before. There are many basic design questions that the few available photos do not answer and so I’ll be making most of this up as I go.
What is a Dyna-Cam? The Dyna-Cam engine has been discussed on HBA in several past threads, but in brief, the Dyna-Cam engine is an axial “barrel” style engine that was developed over several decades (about 1930-2000). The company had it FAA type certified for aircraft use and claimed to be going into production when financial problems tanked the company and halted further progress. You can read more about it at https://dynacam-engine.com It’s now been more than twenty years since Dyna-Cam was bought/went bust and there’s been no further visible work. There are some photos at the link above and there is a marketing style video on YouTube. Other than from these sources, I have found very little information specific to this engine.
The Dyna-Cam engine arranges six double end pistons around a central drive shaft making a twelve cylinder engine. The linear motion of the pistons is translated to rotation of the driveshaft using a sinusoidal cam. Each piston completes all four strokes in one revolution of the driveshaft. Here are two animations I made to demonstrate this arrangement:
So what do you think? Why aren’t there more axial engines in use? What are the flaws and how can they be overcome? Has anyone seen a Dyna-Cam in person? Seen the insides? Any further info on this design concept is greatly appreciated!
Axial cam engines have advantages that make them appealing for aviation use. They can be relatively compact and low profile, allowing more streamlined cowlings. They turn slowly, the driveshaft turns at camshaft speed, providing lots of torque at low RPM, excellent for direct drive and large diameter propellers. They can have perfect balance, and with a power pulse every 30 degrees (for a 12 cyl engine), should run very smoothly. So why isn’t there an axial in every piston power plane? I don’t know. There clearly must be some flaws and difficulties in building these engines or we would have more working examples, but maybe these can be solved or worked around.
I have decided that the best way forward for me is to copy the “Dyna-Cam” engine basic design while modernizing where possible. There is just enough information available on the Dyna-Cam engine to convince me the basic concept has merit, but little enough information to avoid feeling like this has all been done before. There are many basic design questions that the few available photos do not answer and so I’ll be making most of this up as I go.
What is a Dyna-Cam? The Dyna-Cam engine has been discussed on HBA in several past threads, but in brief, the Dyna-Cam engine is an axial “barrel” style engine that was developed over several decades (about 1930-2000). The company had it FAA type certified for aircraft use and claimed to be going into production when financial problems tanked the company and halted further progress. You can read more about it at https://dynacam-engine.com It’s now been more than twenty years since Dyna-Cam was bought/went bust and there’s been no further visible work. There are some photos at the link above and there is a marketing style video on YouTube. Other than from these sources, I have found very little information specific to this engine.
The Dyna-Cam engine arranges six double end pistons around a central drive shaft making a twelve cylinder engine. The linear motion of the pistons is translated to rotation of the driveshaft using a sinusoidal cam. Each piston completes all four strokes in one revolution of the driveshaft. Here are two animations I made to demonstrate this arrangement:
So what do you think? Why aren’t there more axial engines in use? What are the flaws and how can they be overcome? Has anyone seen a Dyna-Cam in person? Seen the insides? Any further info on this design concept is greatly appreciated!
