#1730127 - 10/12/06 11:46 PM
Re: AH-1 Cobra Question
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I B Spectre
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Sorry if there was a misunderstanding, but I've never flown any type of helicopter. However, I did receive training oriented toward maintenance, systems and operation of the AH-1W.
To answer your question, though, you have to consider the basic differences in doctrines of the U.S. Army and the USMC. The Marines are tasked with being capable of fast deployment meant to secure and hold certain objectives until the larger, heavier Army assets can be brought to bear. Note that this is longstanding doctrine for primarily conventional engagement, not necessarily how the Marines have actually been employed in recent conflicts.
That being said, the Cobra is a smaller, lighter aircraft which lends itself more easily to transport by varying sizes of ships and aircraft (C-5, C-17). Being more compact than an Apache means more can be carried on helicopter assault ships. That's one of the reasons it has stuck with the two-bladed rotor, although I've read there are variants coming with four-bladed rotors. Of course this will necessitate some sort of bladefold capability which might be done manually rather than a complex powered system. IIRC, the engines are the same for the Cobra as for the Apache, but my schooling is approaching 15 years ago. The Cobra carries less armament than the Apache, but being lighter and smaller has its advantages.
I've never received any training on the AH-64, but I've always had an interest in military aviation, so I read a lot. The Apache is more analogous to a Navy destroyer whereas the Cobra might be thought of as a PT boat. The Apache's heavier armament, heavier armor, and sensor suite work well for the autonomous hunter/killer role. While it is quite maneuverable, I would suspect the Cobra would hold the edge by simple physics having to do with mass and inertia. The Cobra's role is that of Close Support rather than autonomous hunting. The Cobra crew works with forward observers whose role is to locate, identify and coordinate the Cobra's attack. Basically, the're two different tools for different missions, both sharing similar capabilities.
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#1730129 - 10/13/06 07:27 AM
Re: AH-1 Cobra Question
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Shadow=ASP=
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Originally posted by I B Spectre: ...the Cobra is a smaller, lighter aircraft which lends itself more easily to transport by varying sizes of ships and aircraft (C-5, C-17). Being more compact than an Apache means more can be carried on helicopter assault ships. Won't that change quite drasticaly when they get the AH-1z? Unless I'm mistaken the z-model is allmost identical in length, height and width to an Apache (it still looks skinny though).
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#1730130 - 10/13/06 09:59 PM
Re: AH-1 Cobra Question
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Franze
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Originally posted by I B Spectre: While it is quite maneuverable, I would suspect the Cobra would hold the edge by simple physics having to do with mass and inertia. The Cobra's role is that of Close Support rather than autonomous hunting. The Cobra crew works with forward observers whose role is to locate, identify and coordinate the Cobra's attack. Basically, the're two different tools for different missions, both sharing similar capabilities. Sorry, I gotta nitpick this. Although you wouldn't think it, the force of physics really isn't on the Cobra's side as one would expect. I'm recalling from memory what my father told me (who is a former UH-1 and UH-60 pilot) when comparing Apache and Cobra. The number one reason is the Cobra's lack of a fully articulated rotor system is a royal pain in the ass when it comes to manuevers. From a pure forward-backward, left-right standpoint, the Cobra might hold an advantage in maximum speed and acceleration, but that's where it ends. Loops, negative G maneuvers, etc. are beyond what the standard two bladed xH-1s can do - if they try, the rotor has a way of breaking off it's bearings and going through either the cockpit or the tail. With Apache, that's not an issue - the rotor can flex to the point of maintaining agility but without the danger of a catastrophic failure. The disadvantages of Apache, as we know, are cost and complexity plus maintenance hours. But from a strict maneuverability standpoint, Cobra would lose on technical grounds big time. This is being challenged by the Zulu model now, but I've yet to see a whole lot of news on that, plus the Zulu really trades what the Whiskey was for what the Apache currently is.
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#1730131 - 10/14/06 12:38 AM
Re: AH-1 Cobra Question
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I B Spectre
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As interesting and impressive as the Apache's ability to loop and roll is, I don't think it's in the combat pilot's bag-o-tricks for use in the field of battle. As for negative-G maneuvers, every aircraft has design limits and maybe the Cobra's is less than the Apache's, but again, you have to consider the mission profile. Autonomous hunting seems more likely to require hard maneuvering, particularly in highly varied topography. I think it far more likely the forward and back, side-to-side maneuvering would be the norm for CAS and acceleration can always be useful. I'm not pitting the Apache against the Cobra, like I said, they're two different tools, two different missions, with similar capabilities.
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#1730134 - 10/14/06 09:42 PM
Re: AH-1 Cobra Question
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I B Spectre
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The four-bladed rotor in itself has several benefits, not the least of which is reduced noise. The Cobra's VSS (Vibration Suppression System) is quite a solution to stability issues related to the downwash pulses causes by the nearly three-feet wide blades. The result of increase pulse frequency should make for less vibes, hence, better stability. More on the Zebra model here: http://www.bellhelicopter.textron.com/en/aircraft/military/bellAH-1Z.cfm and http://www.globalsecurity.org/military/systems/aircraft/ah-1z.htm I can't think of any A2A instance where rolling of a helicopter about its longitudinal axis would be beneficial. Unlike a fixed wing aircraft, you aren't going to get a vector roll benefit from a chopper. The concept of the helicopter dogfight is interesting, but have there been any documented? The hammerhead is a valid maneuver for exchanging speed for altitude, executing a 180 degree turn and recapturing the energy on the way back down. You just gotta be sure that when you come to that temporary stop at the top, you don't present yourself as a sitting duck.
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