CRAN
There is no disagreement with what you are saying. The Lycoming is already considered a reliable engine, so to have two of them would be over
-reliability.
I am suggesting going in the other direction. For example, use two lightweight 2-stroke engines. They will have less reliability than a Lycoming, but the probability of the simultaneous failures of both engines should be much less frequent than the failure rate of the single Lycoming. Hopefully, this would offer a greater time between complete failures, plus a reduced total weight.
Lu,
Yes, the total failure rate will be higher, but the second engine need only support the craft at the minimum power setting, and possibly only until a safe landing site was found.
The following example is not going to deliver the horsepower that CRAN is talking of but it does convey the basic concept.. Hirth has developed a
2-cylinder inline engine for the single seat Ultrasport helicopter, and
4-cylinder opposed engine for the two seat Ultrasport helicopter. Most of the components are common to both engines.
The idea would be to position the 2-cylinder engines in an opposed arraignment. This would cause these engines to be very similar to a single opposed 4-cylinder engine, except that there are two crankshafts. Just as Hirth has modified two engines specifically for helicopters, they might be willing to develop a lower crankcase housing for two crankshafts. Of course, they would have to synchronize the engines etc., but this should not be a significant problem.