# Airbus RACER: helicopter of the future?



## Brian G Turner (Jun 27, 2017)

This has got a lot of coverage in the papers today - a helicopter with additional turbines to allow for speeds of up to 250 mph:

Airbus Helicopters reveals Racer high-speed demonstrator configuration


----------



## SilentRoamer (Jun 27, 2017)

I bet it can't do silent mode like Air Wolf and hover 30ft above peoples heads without being noticed....

Just saying...


----------



## Vertigo (Jun 27, 2017)

It's good that it's meant to be efficient and all that but I don't see that it's particularly revolutionary. The existing speed record for a helicopter is 249mph and the physics dictates that helicopters are unlikely to ever get any faster than that unless they became capable of dynamically changing their main blade configuration.

The reason for this is that close to the base of each blade the airflow over the blade can/will end up flowing in reverse. If you imagine a helicopter travelling at 250mph then the air is flowing from front to back at the main rotor axle at 250mph therefore when the blade is retreating (travelling in the opposite direction to the aircraft) it must be travelling at more than 250mph to get positive lift and this will not be the case at the base of the blade. The faster the helicopter travels the further out along the blade you must go to find positive lift. Some helicopters can cope with as much as 40% of the blade having this reverse flow, but that's about it. Secondly the tips of the advancing blades start travelling so fast that they are close to the speed of sound (or indeed over it) and begin generating shock waves creating something known as "shock induced flow separation," which I don't fully understand but it can lead to high speed stalling.

So whilst airbus seem to be making much of its speed I'm not sure that's what's really important.


----------

