Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - SMM (Power Density improvement demonstrated on a certified engine)

Teaser

The objective of the project is to look at methods of improving the power-weight ratio of a diesel fuelled piston engine for light aircraft use. Improving the power-weight ratio of the engine will increase aircraft performance as well as reducing fuel consumption / CO2. This...

Summary

The objective of the project is to look at methods of improving the power-weight ratio of a diesel fuelled piston engine for light aircraft use. Improving the power-weight ratio of the engine will increase aircraft performance as well as reducing fuel consumption / CO2. This has obvious environmental benefits as well as reduced operating costs for the aircraft owner. These improvements would make the engine more competitive in the market which should lead to more sales and in turn the potential to increase employment.

Increasing the engine performance of the engine is easily achieved by changes to the fuel injection system on the engine. However, this increased performance results in higher loads on the engine due to the increase in pressure and temperature within the cylinders during combustion. The design of the base engine for this project had been optimised for its current performance level and increasing performance results in a reduction in the life of many of the main structural components of the engine.

The project is therefore challenging in that it requires many of the components to have increased strength and stiffness but also reduced mass. This was achieved by careful detail design of the components, alternative materials and methods of construction of the engine. FEA stress analysis was used to validate that the revised components could meet the durability requirements with the increased loads.

Work performed

Work Package 1 was the preparation phase, where the existing engine was examining and discussions help with the supplier about know weak points. Some preliminary FEA stress analysis was carried out on a couple of engine components to understand the potential challenges and opportunities for weight reduction. Using this information and via regular meetings with the engine supplier and detailed scope of work was defined and a project timing plan produced.

Work Package 2 was the main technical phase of the project where the engine components defined in WP1 were redesigned to improve their strength and reduce their mass. An alternative method of construction was utilised for the main engine crankcase, this was done to improve its strength as well as simplify the manufacturing of the part. The cylinder barrels very also redesigned around an alternative manufacturing method as these parts were targeted as the item with the largest potential for weight saving. A by-product of the alternative design was also an improvement in the cooling of the cylinder barrels. The cylinder heads were redesigned to reduce their mass and CFD analysis was carried out to also improve the cooling of these parts. A number of smaller components were also redesigned to reduce mass and accommodate the changes made to the other engine components. The FEA stress analysis showed that all components could achieve the desired engine life at the increased loads for the project. The CFD results also demonstrated improved cooling for the engine which would also have a positive impact on the engine durability.

Work Package 3 was the manufacture of parts to the new design so that a prototype engine could be assembled and tested in Work Package 4. Castings were procured for the major structural components of the engine and as of the end of Reporting Period 1 ( 30/6/17 ), the castings had been received and they were part way through the process of being machined into finished components.

Final results

An alternative construction has been used for the design of the crankcase which is novel within the air-cooled light aircraft engine market. Analysis work in WP2 has shown that there is a significant increase in the strength and stiffness of the crankcases by using these new techniques with only a small penalty in mass. The new design of crankcase is also significantly simpler to manufacture which will reduce the cost of manufacturing the engine and make it more cost competitive.

The design of the cylinder barrels is also unique within the air-cooled light aircraft engine market. The new methodology reduces the mass of the cylinder barrel assembly by over 35%, this will improve the power to weight ratio of the engine.

Both of the above two innovations should make the redesigned engine more competitive in the market which should lead to more sales and the potential for increased employment.