User:SvingenB/sandbox

Summary
This article tries to compare and define various available and potentially available VW engine conversion and VW based engines used in light airplanes today. This is done on the basis of numbers and facts. It is a simple compilation of data for further study and reference.

History
A short historical background is needed to put things into perspective. VW engines has since just after the second world war been used in light aircraft. The history is different in different parts of the world, and the "industry" developed around these engines has done so surprisingly independent from each other, and with different focus. All types of VW boxer engines has been used as aircraft engines, not just the beetle engine.

France
This is where the earliest utilization of VW engines in aircraft started. This started just after the second world war. The countryside in France were then literally littered with abandoned Kubelwagen, the German version of the Jeep. The Kubelwagen used a VW boxer engine, the Beetle engine. French aviation enthusiasts simply took these engines off the Kubelwagen, mounted propellers on them and used them in all kinds of small airplanes. Several small companies grew up from these early adopters, notably JPX, Hapi, Rectimo and others. Today all production of VW aircraft engines seems to have stopped completely in France. The engines from France are all based on the Type-1 VW engine (beetle engine), except late JPX engines that were extensively modified.

Germany
In Germany this development started much later than in France. The first engines started to be available in the mid 1970s. The use of these engines in Germany was first and foremost in certified motorgliders, hence the engines also was certified accordingly. Two notable companies grew up, Limbach and Sauer. Limbach has produced more than 6000 VW based engines, while Sauer has close to 1000. The engines used as base was the Type 1 engine and the much more solid Wasserboxer. The engines from Sauer and Limbach represent the most advanced and most powerfull VW conversions available. Since all parts are custom made for aviation use, they are more correctly described as VW based rather than a VW conversion. Together about 7000 engines have been produced and the production is still going. Sauer has been able to convert the production to substantially less costly non-certified units for the ultralight market, engines able to compete even with Rotax 912 on price/performance. Nevertheless, it is definitely correct to say that the peek of production and sales from both companies lies in the past.

Another notably producer is Grob. Their engines were used in their Grob G109 motorglider. Although low in volume and the engine were not available as a stand alone product, Grob is the sole example of using the Type 4 VW engine as an aircraft engine.

USA
Rather oddly at first thought, this is were the VW conversion business is flourishing today. It is hard to point at one specific reason here, but where the companies like Limbach, Sauer and JPX focused on high tech, certified and therefore very costly production, the American companies adopted a down to earth grass-root approach. This grass-root approach often (but not always), consists of selling engine kits rather than complete engines. These kits typically use off the shelf automotive parts for the core engine parts (casing, cylinders, piston etc) instead of all custom made as the Sauers and Limbachs. Custom made parts are only used where needed (crank shaft, cam shaft, ignition, carburetor typically). Whatever they may lack in refinement and horsepower, they make up for in availability and low cost. Were the German engines were part of the very high tech, and very German and expensive, gliding industry, the American engines were a major part of the grass-root experimental aircraft movement (EAA) growing up from the late 1950s. All the available American engines are Type 1 based, and are experimental engines.

For instance, a non certified Sauer S 2200 UL cost twice as much as an AeroVee, and a certified Limbach L 2000 cost twice as much as a non certified Sauer S 2100 UL. All these 3 engines have similar performance and all are type 1 VW conversions.

Brazil
Brazil has a long tradition of manufacturing VW engines and cars. Lately a new VW based engine have been seen in the news and at stands. It is the Motorav. This engine appears to be have a redesigned casing and a redesigned cylinder head, but is basically a VW engine (the pictures of their engines and the drawings does not appears to be consistent though). Three engines are on their list. If they will be available in the USA and Europe, or at all, remains to be seen.

Type 1
The Type 1 series of engines are the most widely used engine for VW aircraft conversion. This engine is simple and light.

Wasserboxer
The Wasserboxer is a further development of the Type 1 engine. The Wasserboxer was used on late VW vans. The casing of the Waserboxer is much stronger built than the Type 1 since it was designed for 112 HP and 2100cc displacement, not 40 HP and 1200cc displacement as the Type 1. Still, it is of same length and only about 7 kg heavier. The Wasserboxer type of crankcase is used on all larger Limbach and Sauer engines.

Type 4
The Type 4 engine is a different engine altogether from the Type 1, larger and heavier, yet very similar in appearance. It was air cooled. It was used on the 411 and 412 series of VW cars. Only Grob is known to have used this engine as an aircraft engine, the Grob 2500 used in the Grob G109 motorglider. Even though not available today by any manufacturer, it is included below since many motorgliders have this engine installed today.

Characteristics
The specs are taken from the manufacturers web sites.
 * AeroVee 2.1 is the kit engine from Aeroconversions
 * GP is the kit engines from Great Plains
 * Grob 2500 is the Grob Aircraft VW type 4 conversion
 * Hu is the Hummel engine
 * JPX is the JPX engines
 * L is the Limbach engines
 * M is the Motorav engines
 * R-2300 is the Revmaster R-2300 engine
 * S is the Sauer engines
 * Orange is obsolete engines (not sold today, but in use), and green is engines in development.

Bore and Stroke
Since the VW based engines are all built around the same theme, the main difference is bore and stroke. It will therefore be very easy to compare the different engines by plotting them into a table with stroke along the x-axis and bore along the y-axis. This is plotted along with the corresponding bore/stroke ratio.

Crankcase and displacement
Different crankcases are used; VW "Type-1", VW "Wasserboxer", VW "Type-4" and a few custom made. These are plotted in the same bore and stroke table as above along with the displacement.