Bell 412
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Yes, the fully articulate rotor head is the best. Anything else is a compromise. You sacrifice when ever you restrict the blade's movements in all planes. You reduce costs and ride comfort also. The US military can afford the best so go with it. These heads are out of the usual operator's price range so they compromise. US military would certainly go to a fully rigid or semi-rigid head if it was the BEST. They are not. As usual, deep pockets get you the best.
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"I don't think you can say any one design is the best. It really depends what you want to do with the helicopter and what limitations reality impose."
A fully articulated hub can do everything you want ANY helo to do, only better. Consequently, a rigid and semi rigid hub can't do everything a fully articulated hub can do so therefore what's best?
A fully articulated hub can do everything you want ANY helo to do, only better. Consequently, a rigid and semi rigid hub can't do everything a fully articulated hub can do so therefore what's best?
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Dan-
"Consequently" means "as a result". That's what we call a non sequitir. Your conclusion doesn't follow from your premise. Or, your sentence makes no sense.
Neither does your argument.
Explain the below three machines as justifications for your argument. You might be able to pull off the last two, but only with a weak argument. You won't be able to do the first one. (Nor the Dauphin, BO-105, and several others). Extra credit if you can figure out what other physical characteristic these machines have in common (very approximately) other than broadly the type of rotorhead (I don't believe you will find that any of them are articulated... unless it means something different to you than it does to me).
Comanche (RAH-66)
Venom (UH-1Y)
Viper (AH-1Z)
I happen to side with Matthew on this one. Part of the "best" design is making sure it's light enough to get in the air, has the proper inertial characteristics for the helicopter it's made for, and the target customer can afford to buy it. A helicopter that's too expensive for the target customer is not a good design, it's a lost opportunity.
"Consequently" means "as a result". That's what we call a non sequitir. Your conclusion doesn't follow from your premise. Or, your sentence makes no sense.
Neither does your argument.
Explain the below three machines as justifications for your argument. You might be able to pull off the last two, but only with a weak argument. You won't be able to do the first one. (Nor the Dauphin, BO-105, and several others). Extra credit if you can figure out what other physical characteristic these machines have in common (very approximately) other than broadly the type of rotorhead (I don't believe you will find that any of them are articulated... unless it means something different to you than it does to me).
Comanche (RAH-66)
Venom (UH-1Y)
Viper (AH-1Z)
I happen to side with Matthew on this one. Part of the "best" design is making sure it's light enough to get in the air, has the proper inertial characteristics for the helicopter it's made for, and the target customer can afford to buy it. A helicopter that's too expensive for the target customer is not a good design, it's a lost opportunity.
Last edited by Um... lifting...; 23rd Sep 2007 at 04:26.
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I apologize for my GED education that only allowed me to fly H-1s and then H-60s. Like us all, we are loyal to our helo and swear nothing is better...especially if your stuck with it. We were forced into the H-60 and like puppies our eyes were opened. I can only imagine what the H-53, H-92 and S-76 must be like since it was like night and day going from the H-1 to H-60. These two are the only helos I can speak to about but if you believe a rigid rotor is better than a fully articualed, more power to your superior intelect. Keep the shiny side up Pal. Best.
Dan
Dan
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I didn't try to define "best", but as Matthew pointed out, it's going to depend upon a lot of things.
Dan, if I insulted you, I apologize. I've got no argument with you that an articulating head is a better performance choice than a semi-rigid underslung, and depending upon the machine, it can have better performance than a rigid head. But, it depends a lot upon the machine and what it's planned to be used for. In a light helicopter, a semi-rigid underslung is a good choice that has proven itself over time. It's not the best functional choice for an attack helicopter, but it works. It's not state of the art, but within its limitations, it does what it's supposed to. As Nick Lappos has pointed out to me on a few occasions, things aren't always what they initially appear to be to we pilots in helicopters and I've had more than one of my incorrect ideas put on a spit and barbecued. I went from flying a teetering head to flying an elastomeric head (with what is now about 30-year-old technology) to a different company's elastomeric head to going back to that same teetering head to a newer elastomeric head to an even newer elastomeric head with a few articulated heads tossed in there along the way for fun. To go from teetering to a more responsive head is like going from your Mom's Dodge to a sports car. You're really bound to like it. To go from a single-engine H-1 to a UH-60... well, same thing.
It's been my observation that a rigid head is a great choice for a small-medium size helicopter. They're simple to maintain, durable, can have a low radar signature, are resistant to battle damage, and with the right control system, can be fully aerobatic or nearly so. They haven't, however, scaled up real well into large helicopters so far, which may be part of why you'll see that Eurocopters don't use the same type of head in a SuperPuma as they do in a Dauphin. I wouldn't be surprised though, if somebody was working on it somewhere.
I've seen that an articulated head is terrific for medium-large helicopters and I wasn't saying an articulated head is a bad thing (The Hawk series I think is the most successful military helicopter line ever produced and the S-76 hasn't done too badly either). Since Sikorsky has concentrated their programs on machines that are about 5 or more tons these days, you won't see too many non-articulated heads on Sikorsky machines. Comanche is an exception and is one of the heaviest helicopters with a bearingless rotorhead that I know of. But again, I wouldn't be surprised to see technology from Comanche's rotorhead make it into Sikorsky's other product lines eventually, but I wouldn't know what, when, or how.
And while you, Takan, may think I sound like an accountant (I'm not, I'm an engineer by training, just not an aeronautical one, and I've flown all three basic types of heads, they all have their points) when an engineer figures out a design of any kind, he has to keep in mind that the machine or bridge or building or whatever needs to be able to be affordable to somebody who wants it or it will never leave the drawing board. It doesn't always make sense to use the most sophisticated technology on a simple design. And that's reality. And that was my point. Defining "best" is a slippery beast. I'm not going to ATTEMPT to define it for all helicopters or all things to all people.
And Dan, the military doesn't always get it right. I spent a couple decades in uniform and saw it enough. In the case of the Sikorsky Hawks though, I think they did. I think they got it right with the Hueys too... but that was then. I can't help you with how the H-53, S-92, and S-76 fly (I've only been a passenger in one of those), but my 53E buddies call it 'the sh*tter'. If you ask why, they say it's because it's like sitting on the can and flying your house around.
Dan, if I insulted you, I apologize. I've got no argument with you that an articulating head is a better performance choice than a semi-rigid underslung, and depending upon the machine, it can have better performance than a rigid head. But, it depends a lot upon the machine and what it's planned to be used for. In a light helicopter, a semi-rigid underslung is a good choice that has proven itself over time. It's not the best functional choice for an attack helicopter, but it works. It's not state of the art, but within its limitations, it does what it's supposed to. As Nick Lappos has pointed out to me on a few occasions, things aren't always what they initially appear to be to we pilots in helicopters and I've had more than one of my incorrect ideas put on a spit and barbecued. I went from flying a teetering head to flying an elastomeric head (with what is now about 30-year-old technology) to a different company's elastomeric head to going back to that same teetering head to a newer elastomeric head to an even newer elastomeric head with a few articulated heads tossed in there along the way for fun. To go from teetering to a more responsive head is like going from your Mom's Dodge to a sports car. You're really bound to like it. To go from a single-engine H-1 to a UH-60... well, same thing.
It's been my observation that a rigid head is a great choice for a small-medium size helicopter. They're simple to maintain, durable, can have a low radar signature, are resistant to battle damage, and with the right control system, can be fully aerobatic or nearly so. They haven't, however, scaled up real well into large helicopters so far, which may be part of why you'll see that Eurocopters don't use the same type of head in a SuperPuma as they do in a Dauphin. I wouldn't be surprised though, if somebody was working on it somewhere.
I've seen that an articulated head is terrific for medium-large helicopters and I wasn't saying an articulated head is a bad thing (The Hawk series I think is the most successful military helicopter line ever produced and the S-76 hasn't done too badly either). Since Sikorsky has concentrated their programs on machines that are about 5 or more tons these days, you won't see too many non-articulated heads on Sikorsky machines. Comanche is an exception and is one of the heaviest helicopters with a bearingless rotorhead that I know of. But again, I wouldn't be surprised to see technology from Comanche's rotorhead make it into Sikorsky's other product lines eventually, but I wouldn't know what, when, or how.
And while you, Takan, may think I sound like an accountant (I'm not, I'm an engineer by training, just not an aeronautical one, and I've flown all three basic types of heads, they all have their points) when an engineer figures out a design of any kind, he has to keep in mind that the machine or bridge or building or whatever needs to be able to be affordable to somebody who wants it or it will never leave the drawing board. It doesn't always make sense to use the most sophisticated technology on a simple design. And that's reality. And that was my point. Defining "best" is a slippery beast. I'm not going to ATTEMPT to define it for all helicopters or all things to all people.
And Dan, the military doesn't always get it right. I spent a couple decades in uniform and saw it enough. In the case of the Sikorsky Hawks though, I think they did. I think they got it right with the Hueys too... but that was then. I can't help you with how the H-53, S-92, and S-76 fly (I've only been a passenger in one of those), but my 53E buddies call it 'the sh*tter'. If you ask why, they say it's because it's like sitting on the can and flying your house around.
Last edited by Um... lifting...; 23rd Sep 2007 at 12:50.
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Recently our HP came out of a 2500 hour inspection, if you've never seen a helicopter that you fly in that many pieces, including the main and tail rotor systems, you might not want to.
The aircraft was tracked and balanced in a day and a half with 4 or so flights.
Two of the engineering goals approached by Bell with the 412 were to increase speed and decrease noise as compared to the 212, they achieved both.
Since then, the 212 has been widely referred to as the lifter, and the 412 the cruiser. Ask the folks flying high altitude mining support in Malaysia, I think they will echo this.
I hear/read so many who feel that Bell simply recycles old technology. To the extent that it is functional to the market to do so, they do. After all, a derivative aircraft is normally much cheaper to certify. And, they continue to hold a fair market share.
They do make mistakes, Rogerson and Krados (sp) as a sole source provider for glass displays?
The aircraft was tracked and balanced in a day and a half with 4 or so flights.
Two of the engineering goals approached by Bell with the 412 were to increase speed and decrease noise as compared to the 212, they achieved both.
Since then, the 212 has been widely referred to as the lifter, and the 412 the cruiser. Ask the folks flying high altitude mining support in Malaysia, I think they will echo this.
I hear/read so many who feel that Bell simply recycles old technology. To the extent that it is functional to the market to do so, they do. After all, a derivative aircraft is normally much cheaper to certify. And, they continue to hold a fair market share.
They do make mistakes, Rogerson and Krados (sp) as a sole source provider for glass displays?
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Best means: “Better than ALL others”.
If a fully articulated rotor Can Do ALL the things a rigid or semi rigid rotor can do, then it is simply the Best.
So, regardless of the mission, weight, cost, small, large medium airframe, simplicity, complexity, cuteness, material, blah, blah blah, (get the idea?), if one rotor system can do ALL of this and the other rotor systems cannot, then it is “Better than the others” or BEST.
And yes, I agree the BEST thing to happen to rotor systems is the elastomeric bearing.
BTW, a one-piece fully articulated rotor system would look like the H-60, H-3, H-53 or H-92 not the two rotor hubs laying atop one another which has been described by the marines as the “homo-head”. Yeah, a lot of thought went into that system!
If a fully articulated rotor Can Do ALL the things a rigid or semi rigid rotor can do, then it is simply the Best.
So, regardless of the mission, weight, cost, small, large medium airframe, simplicity, complexity, cuteness, material, blah, blah blah, (get the idea?), if one rotor system can do ALL of this and the other rotor systems cannot, then it is “Better than the others” or BEST.
And yes, I agree the BEST thing to happen to rotor systems is the elastomeric bearing.
BTW, a one-piece fully articulated rotor system would look like the H-60, H-3, H-53 or H-92 not the two rotor hubs laying atop one another which has been described by the marines as the “homo-head”. Yeah, a lot of thought went into that system!
Last edited by Dan Reno; 24th Sep 2007 at 11:39.
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Dan:
If a fully articulated head is truly the best design, why are all the new rotor heads bearingless rotors? (EC-135, MD900, Bell 430, and I'm sure there are others).
If a fully articulated head is truly the best design, why are all the new rotor heads bearingless rotors? (EC-135, MD900, Bell 430, and I'm sure there are others).
Manufacturing costs or maintenance costs?
Most rigid type rotors have a far smalller number of componensts, and most of those componensts are rated "on condition".
I really don't see why someone would continue to invest money in research and production of more expensive rigid rotor designs when we already have all the technology available for a 1960s design fully articulated rotor head.
Those bean counters have to be going ape over this.
Most rigid type rotors have a far smalller number of componensts, and most of those componensts are rated "on condition".
I really don't see why someone would continue to invest money in research and production of more expensive rigid rotor designs when we already have all the technology available for a 1960s design fully articulated rotor head.
Those bean counters have to be going ape over this.
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We're getting off track again with what is the BEST. Refresher:
If a fully articulated rotor Can Do ALL the things a rigid or semi rigid rotor can do, then it is simply the Best.
So, regardless of the mission, weight, cost, small, large medium airframe, simplicity, complexity, cuteness, material, blah, blah blah, (get the idea?), if one rotor system can do ALL of this and the other rotor systems cannot, then it is “Better than the others” or BEST.
If a fully articulated rotor Can Do ALL the things a rigid or semi rigid rotor can do, then it is simply the Best.
So, regardless of the mission, weight, cost, small, large medium airframe, simplicity, complexity, cuteness, material, blah, blah blah, (get the idea?), if one rotor system can do ALL of this and the other rotor systems cannot, then it is “Better than the others” or BEST.
"BTW, a one-piece fully articulated rotor system would look like the H-60, H-3, H-53 or H-92 not the two rotor hubs laying atop one another which has been described by the marines as the “homo-head”. Yeah, a lot of thought went into that system!"
I am not sure how you can define "one piece" this:
or this:
or even this:
Just to explain, rigid rotors, are not "rigid", but most of the hinges in traditional "fully articulated" rotors are replaced by elastomerics or virtual hinging built into the composite structure of the component itself, highly decreasing the number of components necessary to assemple a complete rotor head.
Does that make it more expensive?
I am not sure how you can define "one piece" this:
or this:
or even this:
Just to explain, rigid rotors, are not "rigid", but most of the hinges in traditional "fully articulated" rotors are replaced by elastomerics or virtual hinging built into the composite structure of the component itself, highly decreasing the number of components necessary to assemple a complete rotor head.
Does that make it more expensive?