Quizzes & Puzzles25 mins ago
Helicopter take-off
40 Answers
When a helicopter is running and on the ground what happens to it physically to make it take off? Presumably the rotor speed is increased but is that all, do the blades alter angle (like flaps)? Just wondering.
Answers
So... Ok... where to start? First, the rotors on a helicopter are nothing more than moving wings. If you could see them up close they have the same upper contour as an aircraft wing has and produces lift in the same way. (Thank you Mr. Bernoulli). As the rotor rotates counter clockwise as seen from the cockpit (on American helicopters)
22:45 Fri 07th Oct 2011
-- answer removed --
Thanks Philtaz and hi The Winner, Now a Chinook is one thing I really don't understand how they stay up. Actually I don't know how any helicopter stays up. This has sparked a bit of a discussion - my OH says a plane revving along a runway will take off on its own just based on speed but I think the change of wing shape is required too (the flaps!) to make it lift.
I've been in quite a few helicopters when I served in Northern Ireland and there is no feeling like it.
One of the units I worked in had a Major from the Army Air Corps as its head and on the day I left he organised a flight for me with one of his colleagues in a Gazelle. I was taken on a hedge hopping flight around South Armagh which was finalised by the pilot completing a wing-over (apparently quite dangerous in a heli), which was exhilerating and terrifying at the same time!
One of the units I worked in had a Major from the Army Air Corps as its head and on the day I left he organised a flight for me with one of his colleagues in a Gazelle. I was taken on a hedge hopping flight around South Armagh which was finalised by the pilot completing a wing-over (apparently quite dangerous in a heli), which was exhilerating and terrifying at the same time!
-- answer removed --
Good for him jack, bet your proud.
Philtaz that sounds a great memory. I would be very nervous in a helicopter (I figure if the engine fails you drop like a stone). I live near to a RNAS and see them over my house daily. They do an exercise that looks like hovering in the air but with the nose pointed down not far off vertical - it terrifies me to watch.
Philtaz that sounds a great memory. I would be very nervous in a helicopter (I figure if the engine fails you drop like a stone). I live near to a RNAS and see them over my house daily. They do an exercise that looks like hovering in the air but with the nose pointed down not far off vertical - it terrifies me to watch.
Not sure that's possible methyl. I believe the blades change their angle at the same time and cannot be altered independently. The rotors on the chinook may differ (front to back and vice versa) but not the individual blades, though I may be mistaken.
This may explain it a bit better:
https://www.youtube.com/watch?v=cf5iG299hzk
This may explain it a bit better:
https://www.youtube.com/watch?v=cf5iG299hzk
Not too sure Prudie. I was also based near where they trained RAF helicopter pilots (RAF Shawbury at the time, don't know about present day) and they used to practice engine cut-out drills, which was jaw-dropingly frightening, but only from a certain height, speed and flight direction.
Despite your fears, if you ever get the chance to fly in one go for it, there is nothing like it.
JTH, best wishes for your lad, hope he makes it.
Despite your fears, if you ever get the chance to fly in one go for it, there is nothing like it.
JTH, best wishes for your lad, hope he makes it.
I know .. but I haven't the time right now!
I have done tip checks on a few helicopters (holding a stick and paper up into the rotors whist running) scary : )
Collective and Cyclic pitch are two ways of altering AOA on rotor blades. Check it out.
The weight of the AC is carried/moved along by upward lift through rotor head .. if this angle is a small amount forward of vertical, ac will gain forward speed quite easily.
I have done tip checks on a few helicopters (holding a stick and paper up into the rotors whist running) scary : )
Collective and Cyclic pitch are two ways of altering AOA on rotor blades. Check it out.
The weight of the AC is carried/moved along by upward lift through rotor head .. if this angle is a small amount forward of vertical, ac will gain forward speed quite easily.
-- answer removed --
Hi Prudie,
When a helicopter is on the ground with the blades idling they are exatly edge on to the air. When the heter wwants to tae off the pilot operates a control (cyclic) that increases the rotor speed and the angle of the blades causing them to 'push' more air downwards. The cross section of the blades also causes lift which assists take-off. Most modern helicopters are powered by a jet engine or two which power the rotor and the exhaust is directed back to form forward thrust moving the helicopter forwards. A Chinnok has two jet engines mounted on the rear fuselage. Helicopters steer to left or right by increasing or decreasing the speed of the tail rotor which keeps the machine going straight rather than spinning around it's own main rotor as it would if no tail rotor were fitted (or the linkage breaks).
There are variations such as older helicopters having piston engines and a few having a jet exhaust instead of a tail rotor, but that's generally how helicopters take off, hover and move forwards.
When a helicopter is on the ground with the blades idling they are exatly edge on to the air. When the heter wwants to tae off the pilot operates a control (cyclic) that increases the rotor speed and the angle of the blades causing them to 'push' more air downwards. The cross section of the blades also causes lift which assists take-off. Most modern helicopters are powered by a jet engine or two which power the rotor and the exhaust is directed back to form forward thrust moving the helicopter forwards. A Chinnok has two jet engines mounted on the rear fuselage. Helicopters steer to left or right by increasing or decreasing the speed of the tail rotor which keeps the machine going straight rather than spinning around it's own main rotor as it would if no tail rotor were fitted (or the linkage breaks).
There are variations such as older helicopters having piston engines and a few having a jet exhaust instead of a tail rotor, but that's generally how helicopters take off, hover and move forwards.
