Anyone flown (or fly) the Huey?
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paco,
That film is a German copy of an original made by Sikorsky in the 1950's. The aircraft is an S-56 (H-37 Mojave) as can be told by the position of the tail rotor and the shape of the vertical fin. The scene below is also recognizable, the river with the distinctive island is the Housatonic River that runs by the Sikorsky Stratford, Connecticut factory. I recognize Pope's Island in the river, the helo is right over the plant.
Nick Lappos
That film is a German copy of an original made by Sikorsky in the 1950's. The aircraft is an S-56 (H-37 Mojave) as can be told by the position of the tail rotor and the shape of the vertical fin. The scene below is also recognizable, the river with the distinctive island is the Housatonic River that runs by the Sikorsky Stratford, Connecticut factory. I recognize Pope's Island in the river, the helo is right over the plant.
Nick Lappos
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I have just spent a facinating 10 minutes watching the seemingly impossible bendings and flexing of the rotor blade with some German guy speaking, I can only say I am amazed at the amount of flexing and reverse bending of the leading edge of that blade, my background is in the steel industry, but the materials used in the construction of the blade in question( was it from 1958) are outperforming even the steel produced today(I mean steel, not special steel).
Would it be possible for some of you more engineered based Ppruners to explain the make up of modern blades, and also do modern Blades still perform in the way that the example in the video does?
Peter R-B
Would it be possible for some of you more engineered based Ppruners to explain the make up of modern blades, and also do modern Blades still perform in the way that the example in the video does?
Peter R-B
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Your'e taxing my memory cells.
To: Vfrpilotpb
The Sikorsky blades of that era were made in the following way. The primary load-carrying member is an aluminum spar. The spar is hollow and is extruded. In the extrusion process the interior surface of the spar is formed with several strips in the form of an omega. These omega strips as they were referred to provided a degree of stiffness preventing or limiting inplane or spanwise bending. The spar is hard anodized to protect it from erosion and corrosion.
The spar is placed in a jig that imparts a 7-degree negative twist, which helps to minimize the upward bending of the blade during flight. The inward end of the spar is drilled and a cuff is attached. This cuff is the connection with the rotor head. The trailing edge of the spar has a cut in the upper and lower surface that provides a mechanical connection for the individual pockets. The pockets are the rear portions of the airfoil and there are a number of them depending on the type of blade. The pockets are bonded onto the trailing edge of the spar and are also fitted into the cut thus providing a strong connection to the spar. To complete this process the spar and bonded pockets are placed in an autoclave which sets the bonded surfaces.
The blade is then statically balanced against a known weight. This is done on a knife-edge balance fixture. Weights are added to the outward end of the spar until the blade is in balance. These weights are capable of being moved forward and rearward to provide aerodynamic balance.
Once the blade is complete it is placed on a whirl stand and dynamically balanced against a master blade. The master blade has all of all the desired aerodynamic characteristics, which ensures the ability to change blades without extensive alterations as all of the blades of a given type are aerodynamically the same and are completely interchangeable.
I had to dredge my memory bank almost 48 years. The above description is basic as there is a lot more too it.
The Sikorsky blades of that era were made in the following way. The primary load-carrying member is an aluminum spar. The spar is hollow and is extruded. In the extrusion process the interior surface of the spar is formed with several strips in the form of an omega. These omega strips as they were referred to provided a degree of stiffness preventing or limiting inplane or spanwise bending. The spar is hard anodized to protect it from erosion and corrosion.
The spar is placed in a jig that imparts a 7-degree negative twist, which helps to minimize the upward bending of the blade during flight. The inward end of the spar is drilled and a cuff is attached. This cuff is the connection with the rotor head. The trailing edge of the spar has a cut in the upper and lower surface that provides a mechanical connection for the individual pockets. The pockets are the rear portions of the airfoil and there are a number of them depending on the type of blade. The pockets are bonded onto the trailing edge of the spar and are also fitted into the cut thus providing a strong connection to the spar. To complete this process the spar and bonded pockets are placed in an autoclave which sets the bonded surfaces.
The blade is then statically balanced against a known weight. This is done on a knife-edge balance fixture. Weights are added to the outward end of the spar until the blade is in balance. These weights are capable of being moved forward and rearward to provide aerodynamic balance.
Once the blade is complete it is placed on a whirl stand and dynamically balanced against a master blade. The master blade has all of all the desired aerodynamic characteristics, which ensures the ability to change blades without extensive alterations as all of the blades of a given type are aerodynamically the same and are completely interchangeable.
I had to dredge my memory bank almost 48 years. The above description is basic as there is a lot more too it.
Last edited by Lu Zuckerman; 15th Jul 2004 at 18:05.
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Hey Lu,
What more can be said, not only a star of the Docu TV films but with a memory like Leslie Welsh!
Thanks for the explanation of the Rotor building, with all that effort and work that goes into one single rotor blade and with all the different pieces that go to make up the blade, they must be very tuff and extremely well designed, in order to flex and bend like in the Slomo Vid
My Regards
peter R-B
Vfr
What more can be said, not only a star of the Docu TV films but with a memory like Leslie Welsh!
Thanks for the explanation of the Rotor building, with all that effort and work that goes into one single rotor blade and with all the different pieces that go to make up the blade, they must be very tuff and extremely well designed, in order to flex and bend like in the Slomo Vid
My Regards
peter R-B
Vfr
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UH-1 Question
It may have been explained somewhere before but I cannot find anything so I am asking if any of you guys can explain,
In the Photos contest, nearly the last entry shows a UH1 D, across the top of the rotor and set exactly opposite the path of the main rotors is a bar with what seems like counter weights on the very end, ,
Question What is it, and what does it do?
Regards
Peter R-B
Vfr
In the Photos contest, nearly the last entry shows a UH1 D, across the top of the rotor and set exactly opposite the path of the main rotors is a bar with what seems like counter weights on the very end, ,
Question What is it, and what does it do?
Regards
Peter R-B
Vfr
Hi Peter. The simple answer is that it is a balance bar for the teetering rotor system. I'm sure someone will be along soon to give a more comprehensive answer. 
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That is the "stabilizer bar" a unique piece of mechanical stabilization. It is somewhat rigid in space, because it has weights and is stiffened centrifugally. Since cyclic pitch controls pass thru it, via a linkage, it damps pilot inputs, and also rotor disturbences. In order for the cyclic to get to the rotor blades, the stabilizer bar must be rotated a bit. There are dampers to keep the bar from oscillating while it does its business.
The bar creates a reference for the rotor, so that when a gust disturbs the rotor, the attempt to teeter produces a stabilizing cyclic input to correct the rotor motion. Only pilot control inputs will allow the rotor to teeter.
Some Bell teetering rotors have no bar, and these generally are a bit less stable (but not badly so, frankly). Since the stabilizer bar slows down pilot inputs, it was replaced by electronic SCAS on those models where maneuvering is a virtue. the typical teetering rotor is quite marginal in quick maneuvering, as it is.
The bar creates a reference for the rotor, so that when a gust disturbs the rotor, the attempt to teeter produces a stabilizing cyclic input to correct the rotor motion. Only pilot control inputs will allow the rotor to teeter.
Some Bell teetering rotors have no bar, and these generally are a bit less stable (but not badly so, frankly). Since the stabilizer bar slows down pilot inputs, it was replaced by electronic SCAS on those models where maneuvering is a virtue. the typical teetering rotor is quite marginal in quick maneuvering, as it is.
Pre-flight involves moving the bar to full deflection, centralizing it again, then checking that the the indicator in the fluid sight glassreturns to neutral within 5 secs....I do this daily on the UH1D.
Flew the Jet Ranger a while back, has no stab bar, and is very much twitchier when hovering.
Flew the Jet Ranger a while back, has no stab bar, and is very much twitchier when hovering.
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Gatvol
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Hueymeister wins...................
If you fly the D loaded up, Hot and High. You would really love the H or the new mod with the T53-L703 and extras.
If you fly the D loaded up, Hot and High. You would really love the H or the new mod with the T53-L703 and extras.
Gatvol
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Thanks Nick, thats something I never knew..............
"Make sure it rattles, so you know ithe rotor was not oversped!!"
A few thousand times for me also.
"Make sure it rattles, so you know ithe rotor was not oversped!!"
A few thousand times for me also.
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sticking my neck out
I may regret asking , . . . but what kinds of constraints might have caused Frank not to incorporate this anti-twitchy little feature on the twitchy little R22? (The one I own and have a love-hate relationsip with . . .)
[Supermod: eloquent affirmation that picture worth 1000 words, there, perfect execution!]
[Supermod: eloquent affirmation that picture worth 1000 words, there, perfect execution!]
Avoid imitations
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PA-42,
If the R-22 had the extra weight of a stabiliser bar, the pilot would have to leave his wallet behind in order to lift off
If the R-22 had the extra weight of a stabiliser bar, the pilot would have to leave his wallet behind in order to lift off
No, no, no, Mr Torque;
The moths in a helicopter pilot's wallet lighten the load and make it easier to fly!
The design of rotor heads other than the 47/204/205 is such that they don't need stabilisation. Sure, the R22 is twitchy, but twitchy=responsive. Stable = slow response to inputs. Fighter planes are twitchy, Cessnas and upwards are stable.
The moths in a helicopter pilot's wallet lighten the load and make it easier to fly!
The design of rotor heads other than the 47/204/205 is such that they don't need stabilisation. Sure, the R22 is twitchy, but twitchy=responsive. Stable = slow response to inputs. Fighter planes are twitchy, Cessnas and upwards are stable.
