onetrack, do you consider that common rail injection, solenoid fuel injectors and electronic engine management are 'just fiddling'?
Mechta - Basically, yes. Common-rail injection was in production in the late 1920's. The only difference today is finer control with electronics, and higher rail pressures.
The problem with extremely high rail pressures is that any rupture of the rail can be catastrophic... in the form of damage by the burst, or by the initiation of fire.
In one of Caterpillars latest common-rail, new design engines, Caterpillar have taken the step of positioning the extremely-high-pressure rail, inside a low pressure fuel supply tube.
This is an arrangement that is designed to control and mitigate any danger from any rail burst, by dispersing the burst into the low-pressure tubing.
Solenoid injectors, electronically-controlled, are an improvement on mechanical injection, by allowing staggered injection pulses.
However, the total reliability of engine electronics is still in question... and there needs to be backups in case of electronic-control failure.
Electronic engine controls do not do well in the reliability stakes, because of their inherent lack of robustness.
Diesel engines have won the Le Mans 24 hour race and produced VW Golfs with better performance thah the comparable petrol version, so why do you suggest that applying modern levels of monitoring and control, not to mention 70+ years worth of metallurgical and computerised finite element analysis advances to an opposed piston diesel engine won't bear fruit?
There is only so much that FEA can do, and electronic controls only add small percentages of gain. I don't have a problem with electronic controls per se... they just need to be robust, foolproof, and have backup.
What the basic problem is here, is that there's no MAJOR advancement in IC engine design, with any of the above-mentioned models. Perhaps it's the basic conservativeness of the aircraft fraternity to stick with the tried-and-true.
However, a major advance in engine design is required, to reduce weight substantially, and increase efficiency substantially.
That is why my money is on engine designs such as the Revetec engine. A design that gets away from the basic inefficiency of the rod-and-crank design, and produces a substantially-improved method of transferring reciprocating movement to rotary movement.
In addition, the Revetec engine produces peak torque at very low RPM, and doesn't need to reach high RPM for efficiency. This speaks volumes for vastly improved engine lifespan, as well as being ideally suited for light aircraft propulsion.
Add on a Coates Rotary Valve head to a Revetec engine, and we are talking serious advances in engine design... over the conventional IC piston/poppet valve engine, that has hardly altered, in basic design principles, in nearly 120 years.
If a rotary engine such as the RadMax could solve its sealing problems, then it would possibly be a viable contender in the aircraft propulsion market... however, I believe the sealing problems are insurmountable.
I know Ralph Sarich personally, and I know he spent over 20 yrs trying to solve the sealing problems of the Orbital Engine, and he eventually gave up.
He offered the Orbital Engine to more than a dozen major manufacturers, and not one of them was prepared to swap over to Orbital Engine power, because their best engineers could never come up with a satisfactory answer to the rotary engines sealing problems, either.