Probably the most advanced stock helicopters in KSP today. Reliable, easy to fly, very powerful and with a lot of control options.
One manual for all types, twenty-two pages
By the way ... they're easy to fly but ... you need the manual. Really. Or the engine won't even start.
Azi20 Selene Azi21 Hyperion Azi22 Eos Azi23 Helios
If you're thinking of fuel efficiency, saving Kerbin or other green stuff ... this ain't for you. Helicopters should be like Greek gods: smelly, big, loud, powerful and drink a lot with a bad temper.
February 4th ... exactly two years after I uploaded the first turboshaft. :-)
Update:
It seems Kerbal Joint Reinforcement inhibits correct operation of turboshaft/turboprop engines. Please disable or the engine won't run fast enough for flight.
Engine angular speed at max power without KJR: 24 rad/s.
Engine angular speed at max power with KJR: 10 rad/s.