helicopter thrust
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helicopter thrust
Does anyone know how thrust of a typical helicopter change in forward flight along azimuth angle? What about other manoeuvers?
Last edited by helicopter2009; 27th July 2009 at 17:21.
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From: world
Do you know that what azimuth angle is?
I don't know how the thrust changes with the azimuth angle ( thrust of a helicopter as a function of azimuth angle). Is there anyone who can helps?
thanks Agaricus bisporu
Agaricus bisporu for his/her hint.
Last edited by helicopter2009; 27th July 2009 at 17:34.
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From: Behind a dusty desk, and in some really hot, dusty, wet and cold places subject to who is paying the bill. But mostly Gods own land.
...I trust that the rotor head wont fly off when a helicopter moves into translational flight....
...you could have a legal trust as part of a leasing deal...
...and your trust in the pilot will change if he flys around so as to make you sick...
...you could have a legal trust as part of a leasing deal...
...and your trust in the pilot will change if he flys around so as to make you sick...
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From: Sydney, Oz.
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From: UK
You will find chapter and verse in books or on the internet. The subject of helicopter aerodynamics is far far too large to be answered here, but as I recall it all condenses down somehow to "Big Green Arrows" and "Little Green Arrows"
"Thrust" is a word little used in Helicopter-speak, except in complex descriptions of force-vectors affecting rotor systems and aerodynamics. In such cases it is always attached to other term/s to define it, as in "Forward" thrust "Vector". It's use alone, as you did, is almost meaningless because it is not defined.
Note it's spelling, thrust with an "h", the word you used is totally different, which explains a lot of the posts above.
Happy reading!
ps. Best to get your own knowledge of terminology and language correct before you grizzle at people who do know it correctly...?
"Thrust" is a word little used in Helicopter-speak, except in complex descriptions of force-vectors affecting rotor systems and aerodynamics. In such cases it is always attached to other term/s to define it, as in "Forward" thrust "Vector". It's use alone, as you did, is almost meaningless because it is not defined.
Note it's spelling, thrust with an "h", the word you used is totally different, which explains a lot of the posts above.
Happy reading!
ps. Best to get your own knowledge of terminology and language correct before you grizzle at people who do know it correctly...?
Last edited by Agaricus bisporus; 27th July 2009 at 11:07.
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From: Australia
and I can say with some feeling,
trust in the helicopter game is neither yer arz nor yer muth.
an' trust me,
how long before the colour blind gentlemen of our constituency get the screamin' s***s with the blas*** colour coded entree server.
fair dinkum SP that has got to take the cake as pprune's worsarz nightmare.
trust in the helicopter game is neither yer arz nor yer muth.
an' trust me,
how long before the colour blind gentlemen of our constituency get the screamin' s***s with the blas*** colour coded entree server.
fair dinkum SP that has got to take the cake as pprune's worsarz nightmare.
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From: EGDC
Go on then - I'll bite
Helicopter 2009 - in zero wind (or zero forward speed if you prefer) at a given pitch angle, a rotor blade will produce the same lift (thrust) throughout its 360 degrees of travel.
If you add wind from the front (or forward speed), the blade moving forward from a position over the tail (the advancing blade) will experience increasing airspeed until it is at 90 degrees to the fuselage and then the airspeed will reduce until it get to the nose where it will have the same airspeed as it did over the tail. From nose to tail, the blade (now the retreating blade) will experience reducing airspeed as the wind is coming from behind it - the minimum airspeed position will be at 90 degrees to the fuselage opposite to the maximum airspeed position, then the airspeed will gradually increase again until the blade is over the tail once more having completed a full 360 degrees.
If you increase the airspeed over an aerofoil at a given pitch setting, you will produce more lift (thrust) and if you reduce airspeed you produce less lift.
That hopefully answers your question that lift (thrust) does change in azimuth on a helicopter, but only when there is a difference of airspeed around that azimuth due to wind or forward speed.
Helicopter 2009 - in zero wind (or zero forward speed if you prefer) at a given pitch angle, a rotor blade will produce the same lift (thrust) throughout its 360 degrees of travel.
If you add wind from the front (or forward speed), the blade moving forward from a position over the tail (the advancing blade) will experience increasing airspeed until it is at 90 degrees to the fuselage and then the airspeed will reduce until it get to the nose where it will have the same airspeed as it did over the tail. From nose to tail, the blade (now the retreating blade) will experience reducing airspeed as the wind is coming from behind it - the minimum airspeed position will be at 90 degrees to the fuselage opposite to the maximum airspeed position, then the airspeed will gradually increase again until the blade is over the tail once more having completed a full 360 degrees.
If you increase the airspeed over an aerofoil at a given pitch setting, you will produce more lift (thrust) and if you reduce airspeed you produce less lift.
That hopefully answers your question that lift (thrust) does change in azimuth on a helicopter, but only when there is a difference of airspeed around that azimuth due to wind or forward speed.
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From: UK
The Chinook has an Aft Propulsion Unit (APU), a small jet engine in the aft pylon to give forward thrust thereby allowing the rotors to purely generate lift. The crewmen move from side to side and the CofG change makes the a/c move left or right.
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From: Sydney, Oz.
Originally Posted by WASALOADIE
The Chinook has an Aft Propulsion Unit (APU), a small jet engine in the aft pylon to give forward thrust thereby allowing the rotors to purely generate lift. The crewmen move from side to side and the CofG change makes the a/c move left or right.
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From: UK
how does it change in azimuth?
The front crewman goes right and the back crewman goes left or vice versa, this is DCP (Differential Crewman Position). Pitch is achieved by the crewmen moving forward or aft which is known as Longitudinal Crewman Trim (LCT). Pitch can also be varied by increasing or reducing the power on No1 engine which in turn increases or reduces the speed of the rear rotor thereby increasing or decreasing the lift. Or alternatively by increasing or reducing the power on the No2 engine which gives the same effect on the forward rotor head. If you increase the power on both engines then the lift is increased on both rotor heads and the a/c will lift vertically.
Last edited by WASALOADIE; 28th July 2009 at 16:38. Reason: word change
Avoid imitations
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From: Wandering the FIR and cyberspace often at highly unsociable times
If you increase the power on both engines then the lift is increased on both heads
