Cron
27th Aug 2006, 21:32
Flying Hang Gliders has left me with an obsession regarding what HG Pilots’ call ‘Thermals’ (but I guess there is a more correct meteorological term for them).
I’ve experienced some powerful ‘Thermals’ in the UK and heard tales from around the World where HG’s have been inverted and subsequently broken up because of them.
A couple of days ago in the UK my ever-patient instructor was demonstrating how setting the power correctly in an R22 would keep the airspeed and height and sure enough we settled down to perfect straight and level (He had control). But not long after we started gently climbing (same power and a/s) – instructor explained we were in a thermal.
Back home I calculated the R22 MR disc as 490 sq ft and a Cessna 152 wing area as 159 sq ft.
Are helicopters more susceptible to rising hot air and if so am I right in thinking that the whole disc is influenced by the ‘Thermal’ with a consequent increase in aoa but no reduction in torque?
Thanks for any further information.
I’ve experienced some powerful ‘Thermals’ in the UK and heard tales from around the World where HG’s have been inverted and subsequently broken up because of them.
A couple of days ago in the UK my ever-patient instructor was demonstrating how setting the power correctly in an R22 would keep the airspeed and height and sure enough we settled down to perfect straight and level (He had control). But not long after we started gently climbing (same power and a/s) – instructor explained we were in a thermal.
Back home I calculated the R22 MR disc as 490 sq ft and a Cessna 152 wing area as 159 sq ft.
Are helicopters more susceptible to rising hot air and if so am I right in thinking that the whole disc is influenced by the ‘Thermal’ with a consequent increase in aoa but no reduction in torque?
Thanks for any further information.