Mark 9
Hyperbole aside if such a gearbox weighed 100kg more (1 passenger) wouldn't the trade-off be worth it.
Many years ago I attended a course at Bristol University on helicopter design. One of the lecturers was the Westland head of transmission design who had just produced the Lynx 'conformal' gear system. I remember him saying that If we designed a helicopter gearbox using the design principles of a car gearbox then the helicopter would be too heavy to get airborne. That wasn't hyperbole because in those days car gearboxes were made of cast iron and hugely overengineered to achieve the rigidity needed to tolerate the poor accuracy of the machining used in mass production. These days a typical car gearbox is computer designed and the casting process uses minimal material and is probably made using a weight-saving alloy. Modern mass production also produces components made to very fine tolerances.
My point is that if the car industry can step up to the plate I'm sure the helicopter industry can too. My feeling is the reluctance to go down a new path that will take the current designers down a new path given that 30 years with the same basic design gives them a thorough understanding of the strengths and weaknesses of it. Why take the risk (and spend huge amounts of time and money) going down another pathway when there is no regulatory or customer pressure to change.
The progress made since HARP is unlikely to have been realised if manufacturers had been left to do their thing with no pressure from those that use and regulate their products.
Can a transmission designer add to the debate please.
G.