Engine friction measurements using flywheel deceleration

complete engine with and without compression

Flywheels are used to store kinetic energy. Once a flywheel is accelerated to some rotational speed, it will only slow down because it is transferring energy to a load. By accurately measuring the flywheel’s rate of rotation versus time, we can determine the rate at which the flywheel’s energy is being transferred to the the […]

New power piston and displacer for 3D printed Stirling engine

3D printed Stirling engine displacer parts

To simplify the building of the 3D printed PE 2 Stirling engine I’ve designed and tested two modifications. The parts were printed on a Stratasys printer. Neither of these modifications is required, nor will they alter the performance. If you have built or are building the original design there is no need to change. If you haven’t built those parts you may find the modified parts save a little time and effort. The STL files for the parts are available at thingiverse.

A regenerator for the 3D printed PE 2 Stirling engine

Diagram of the regenertor in the PE 2 engine

This post will examine some of the practical and theoretical aspects of a regenerator as it applies to the 3D printed PE 2 Stirling engine. Those who just want to build a regenerator for the engine and get good performance, will find what they need here too. The above data show my tests of the […]

Power piston sizing for Stirling engines

Power piston and displacer sizing chart for Stirling engines

One of the more difficult yet critical issues in designing your first Stirling engine is deciding on the correct power piston displacement. My earlier discussion of power piston sizing did not satisfy a lot of people. So I’m going to make this one very simple to apply. For me to suggest the right size power […]

Variable reluctance starter motor for Stirling engine

VR3 motor

I chose to use a variable reluctance motor as the starter for my Stirling engine design for the following reasons: 1. The most important feature is that it offers near zero friction when the motor is not energized. The only sources of friction are the shaft bearing drag and aerodynamic drag on the rotor. This […]

Improving solar power when the sun is low in the sky

Light transmission1

Tests on my solar-powered Stirling engine determine it will run with a solar incidence angle of up to 59 degrees, but I would like the engine to work up to 66 degrees incidence or 24 degrees above the horizon. This number is selected because that is the angle that would allow the engine to run […]

Self-starting solar-powered Stirling engine


This is a continuation of my Stirling engine development for a sculpture project that is solar powered. Because this engine needs to autonomously control its operation, it needs to self-start at the proper time. Here’s a video of the engine with starter and controller. This engine is based on the simple Stirling with some significant […]

Generating power with a stepper motor

Current vs RPM

If you want to generate electrical power from about a tenth of a watt up to several watts, a stepper motor might be worth considering. I’m going to go into detail here on a specific stepper motor that can generate up to a little over ½ watt. First a few key features: 1. Inexpensive: New […]

Power Piston Sizing

Engine 3F sim

How big should your Stirling engine power piston be? (Be sure to see my more recent post on power piston sizing. It provides more specific information. — Doug Conner) A common problem Stirling engine designers face is how much volume should the power piston sweep in comparison with the displacer? This of course only applies […]

Simple Stirling 1 performance with and without regenerator

I’ve tried a variety of regenerators on the Simple Stirling 1 engine and the one shown in the photo is simple to make and performs as well as or better than all of the other ones I’ve tried. The test results on the engine with the original displacer and with the modified displacer containing the […]