According to the Oxford English Dictionary an aeroplane is "A powered flying vehicle WITH FIXED WINGS and a weight greater than the air it displaces".
Thank you so much for pointing that out, Coochycool.
As someone who spends quite a lot of his life talking to people about aeroplanes, aircraft and helicopters, I'm a tad ashamed to say I hadn't cottoned on to that nice distinction.
My OED is slightly different to yours - it says
A powered heavier-than-air flying vehicle with fixed wings
- but it's the same meaning....
It also says that
an aircraft is
a machine capable of flight, esp. an aeroplane or helicopter
So, many thanks - I'll be able to get it right in future. And keep my pedant's credentials in situ.
airsound