Stirling Generator
The Stirling Generator Nav depicts a rhombic stirling prototype.

Stirling Engine
These engines were developed back around 1890 and use heat differential to produce output. An engine that runs on temperature differential is very useful. Oddly, no home use unit is available for purchase today. Efficiency and coeffeciency are a subject of much debate.

Basic Designs
There are three basic designs: alpha, beta, gamma, and the advanced design: free piston. Many early builds were alpha. We have passed by the alpha for other designs due to the main issue of seals on the hot side. These wear quickly. We know the rhombic drive beta does not have hot side seals. Free piston designs are based upon a flexible membrane. Free piston designs may hold the highest efficiencies.We wonder if coefficiency can climb higher than 100%.

Working Fluid
The gases inside the cylinders are known as the working fluid. Early versions started with air. Experimenters learned that different working fluids had an effect on performance. Efficiencies climbed highest with the use of helium and hydrogen. [Hmm... wonder where we can get hydrogen.] These molecules are tiny - very difficult to seal.

Working Pressure
We exist at one atmosphere of prerssure. Higher altitudes lower performance. Lower altitudes raise performance. Sealing the engine so it can be pressurized allows for some dramatic increases in performance. Increasing the working pressure makes the design requirements more difficult. Electing the use of little tiny molecules compounds the difficulty of sealing the engine. However, the performance gains are significant for increasing both working fluids and working pressures.

Sealed Output Shaft
Pressurized hydrogen is a dream - well more of a nightmare. Sealing the output shaft at pressure is out of scope for household technology. We must think outside the box. Two options appear: the first is to magnetically couple the output or to move the generator (moving parts) inside the seal. We enlarged the crank area on the rhombic prototype to include a pancake generator. This generator functions within the working fluid. Output shafts are difficult or impossible to seal; while, insulated copper wires are easy to seal.

Linear Generator
The pumping motion of the power piston is a symbiotic motion of the linear generator. There are difficulties but efficiency will raise as we can design and build more symbiotic systems. Free piston and linear generator are probably the eltimate build. We will not start there.

Each build will increase our knowledge and perhaps our efficiency. Many components can be reused in the following build. Asking better questions is the result of a successful build.

Simple and Robust
Although high tech & difficult machining may increase efficiencies. The end goal of simple and robust is the preferred focus. An engine that is easy to work on and maintain is far more valuable than the most efficient. Combining both is the substance.

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