Notar management with engine failure??
Thread Starter
Joined: Feb 2005
Posts: 36
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From: barcelona
Notar management with engine failure??
How does tail rotor system keeps on working, in Notar equiped choppers, during a real engine failure??
I,d appreciate some information regarding this issue.
Adios
I,d appreciate some information regarding this issue.
Adios
Thread Starter
Joined: Feb 2005
Posts: 36
Likes: 0
From: barcelona
Notar management
Mr Nick Lappos:
I simply didnīt know the exact way Notarl system worked.
I knew antitorque force was obtained fron an airflow blown over tail boom end surface, but ignored it came from a fan, itīs been a while without refreshing the manner Notar system works, and I had the idea of the engine delivering somehow this airflow for tail control purposes.
Thank you for the explanation
I simply didnīt know the exact way Notarl system worked.
I knew antitorque force was obtained fron an airflow blown over tail boom end surface, but ignored it came from a fan, itīs been a while without refreshing the manner Notar system works, and I had the idea of the engine delivering somehow this airflow for tail control purposes.
Thank you for the explanation
Joined: Apr 2003
Posts: 1,635
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From: Vancouver, BC, Canada
It would be interesting to know what percentage of the yaw moment of a Notar equipped helicopter comes from the fan generated sideward thrust and what percentage comes from the Coanda effect.
It would then be interesting to know if the Coanda effect is lost when the airflow is from a rotor that is in the autorotational state.
It would then be interesting to know if the Coanda effect is lost when the airflow is from a rotor that is in the autorotational state.
There are no limits
Joined: May 2002
Posts: 506
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From: Shrewsbury, England.
It is my understanding that the Coanda effect accounts for up to 60% of anti-torque thrust in the hover.
In autorotation anti-torque thrust required must be minimal so can be overcome by using the jet thruster.
In autorotation anti-torque thrust required must be minimal so can be overcome by using the jet thruster.
Joined: Apr 2003
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From: USA
the NOTAR derives no thrust from the Coanda effect except when in a steady hover, at speeds below about 10 knots (6 knots rearward). Only when a stream of air blows on the cone from the rotor (only in a low speed hover) can there be any coanda effect.
The NOTAR'S technology has been vastly oversold, it is mostly a tip fan device, the tailcone slots are effective across a tiny percentage of its envelope.
In hover, forward flight, low speed maneuvering the tip jet is the principal source of yaw control. Yes, in a steady hover at low speed, it is possible that half the anti-torque comes from the slotted tail cone, but minor fight deviations from that steady hover cause the Coanda effect to vanish.
The NOTAR'S technology has been vastly oversold, it is mostly a tip fan device, the tailcone slots are effective across a tiny percentage of its envelope.
In hover, forward flight, low speed maneuvering the tip jet is the principal source of yaw control. Yes, in a steady hover at low speed, it is possible that half the anti-torque comes from the slotted tail cone, but minor fight deviations from that steady hover cause the Coanda effect to vanish.
Joined: Apr 2003
Posts: 3,012
Likes: 1
From: USA
Absolutely, Dave, most helos use the vertical fin for the trimmed anti-torque in cruise, as a power saving trick, since fin thrust is much more efficient than rotor thrust.
Maneuvering is done through the rotor, though.
In most helos, the tail rotor power consumption in cruise is that necessary to turn the box and the blades at near zero thrust. NOTAR is no exception, in fact, in some NOTAR models the fins have a rudder so that even electronic stabiity is done through the fin.
Maneuvering is done through the rotor, though.
In most helos, the tail rotor power consumption in cruise is that necessary to turn the box and the blades at near zero thrust. NOTAR is no exception, in fact, in some NOTAR models the fins have a rudder so that even electronic stabiity is done through the fin.
