We call these engines our Nano Flux engines. They are a thermoacoustic engine and works on a different principle to most other hot air engines. It still uses a temperature difference to operate and is powered using a small burner. It is offered as a single or twin engine. Both available in kit or assembled form.

So what is a Thermoacoustic engine?

Thermoacoustic engines are known by several names, including resonant engine, lag engine and lamina flow engine. Conventional Stirling engines have a power piston and a second piston that shuttles air between the hot and cold parts of the engine (known as a displacer piston). In Stirling engines the displacer shuttles the air between the hot and cold sides of the engine. As the air warms up or cools, the air expands or contracts, which pushes or pulls the power piston. Thermoacoustic engines don’t use a displacer piston to shuttle the air around. Instead they utilise a Standing-wave to do the work of a displacement piston. This sound/pressure wave is out of phase with the piston (hence the term lag engine). Inside the engine near the hot end on the engine there is 'stack'. This is in the form of dense metal wool. This is a critical part of the engine and can be considered the equivalent of a Stirling engine's displacer. It reduces the working volume and acts as a sort of 'choke'. It creates the delay in the pressure wave. Heat is provided by a small methylated spirit (denatured alcohol) burner which is provided with the engine. The cold side is cooled with a metal heatsink. Because there is only one connecting rod, backlash and drag is effectively halved in comparison with a conventional hot air engine. The absence of a phased displacer also means that this engine is multi-directional, in other words it can operate with the flywheel rotating either way.

2 Engines available

We have designed 2 new engines. A single cylinder thermoacoustic engine and a twin cylinder version for twice the fun!

Choose between kits or assembled!

For simplicity and quickness you can buy our assembled versions. Sample assembly instructions However many of our customers love to build their engines. You get the delight to see how the inner workings are constructed and see all the parts in their glory. So for this Kickstarter project we spent the extra time to develop the kit versions. The assembly instructions are provided in a 27 page high resolution PDF document. We leave it to you to choose between assembled or kit!

History of Thermoacoustics

For hundreds of years glass blowers noticed an interesting phenomenon; that when a hot glass bulb was joined to a cold glass tube sometimes the newly form glass part would produce a sound from the end of the tube. The phenomenon appeared to be particular and only occurred when the size and ratios were suitable. In the 1700s and 1800s a number of scientist made discoveries with thermoacoustics. These included Byron Higgins (1777), Sondhauss (1850 ), Rijke (1859 ). Sondhauss work is regarded as the ancestor of a standing-wave thermoacoustic devices with Rijke tubes regarded as the ancestors of traveling-wave thermoacoustic machines. In 1962 Carter, R.L., White, M. and Steele, A.M. at the Atomics International Division of North American Aviation Inc created the world’s first thermoacoustic engine, producing 27 watts of power from 600 W of heat.

Thermoacoustic engine advantages

• High RPMs compared to similar hot air engines
• Reduced component count
• Reduced drag
• Multi-directional
• Single connecting rod
• Rapid increase in speed

Operation

The engines come with a burner and wick. The only things you will need is fuel and something to light the wick with. The engine is designed to run from methylated spirits (Denatured alcohol) which is widely available around the world. You will need to push the wick into the burner top, leaving it to protrude about 4mm (1/6 inch). The rest of the wick can remain curled up in the base of the burner. You then fill the burner with no more than ¾ full. Half full will last a long time running the engine. Put the lid of the burner on and place the burner into the base. It fits snuggly.