Planes, helicopters
February 25, 2005 7:27 AM Subscribe
Is a plane easier to pilot than a helicopter? If so, why?
A plane reacts in expected ways to expected inputs. Helicopters just crash.
posted by smackfu at 7:50 AM on February 25, 2005
posted by smackfu at 7:50 AM on February 25, 2005
I've not flown a helicopter, so take this answer with a grain of salt (corrections are welcome). However I have flown a plane, and have studied the aerodynamics of helicopter design. My knee jerk answer would be that airplanes are easier for three reasons:
1) There is at least one less axis to control (plane: pitch, yaw, roll, throttle; heli: cyclic(2), tail rotor, collective, throttle).
2) For most airplanes, the control axis are relatively independant. That is, you can be reasonably sure pitching the nose up will do just that. Helicopters are more fussy. For example, the position of the cyclic pitch, (and the airspeed) affects how the aircraft responds to the collective pitch. This can lead to nasty situations where the pilot's corrective actions make a situation worse. (anyone have stories?)
3) Older helicoptors addressed issues of aerodynamic stability with hinged rotors on a tall stalk. As a result, these aircraft responded relatively slowly to pilot inputs, making pilot induced oscillation a real threat.
Two last things: First, easier is subjective. I've heard that pilots trained on helicopters first find them much easier than fixed-wings. Lastly, fly-by-wire technologies, which are making their first appearances in helicopters, are helping to address the issues I've listed. Besides, helicopters are WAY cooler.
posted by Popular Ethics at 7:50 AM on February 25, 2005
1) There is at least one less axis to control (plane: pitch, yaw, roll, throttle; heli: cyclic(2), tail rotor, collective, throttle).
2) For most airplanes, the control axis are relatively independant. That is, you can be reasonably sure pitching the nose up will do just that. Helicopters are more fussy. For example, the position of the cyclic pitch, (and the airspeed) affects how the aircraft responds to the collective pitch. This can lead to nasty situations where the pilot's corrective actions make a situation worse. (anyone have stories?)
3) Older helicoptors addressed issues of aerodynamic stability with hinged rotors on a tall stalk. As a result, these aircraft responded relatively slowly to pilot inputs, making pilot induced oscillation a real threat.
Two last things: First, easier is subjective. I've heard that pilots trained on helicopters first find them much easier than fixed-wings. Lastly, fly-by-wire technologies, which are making their first appearances in helicopters, are helping to address the issues I've listed. Besides, helicopters are WAY cooler.
posted by Popular Ethics at 7:50 AM on February 25, 2005
The way I heard it explained, in a movie or a book, I think, is thus:
By shape and design, an airplane wants to fly, if it looses all power in the air, it will still convert downwards potential energy in to forward flight and can probably glide to a safe landing.
A helicopter is a big lump of metal that yanks itself in to the air and stays there by expending a lot of effort, it if looses power in the air, you're pretty much boned.
(IANAP)
posted by Capn at 7:56 AM on February 25, 2005
By shape and design, an airplane wants to fly, if it looses all power in the air, it will still convert downwards potential energy in to forward flight and can probably glide to a safe landing.
A helicopter is a big lump of metal that yanks itself in to the air and stays there by expending a lot of effort, it if looses power in the air, you're pretty much boned.
(IANAP)
posted by Capn at 7:56 AM on February 25, 2005
I've flown a plane, but not a helicopter. Still, as a helicopter pilot explained to me, the relative speed of the rotors is higher as they move forward and lower as they move backwards (relative speed is the actual speed of the rotors, but also the speed of the wind and your forward momentum -- so, as you're going forward into the wind you're going comparatively faster relative to the wind and as you're moving away from the wind, you're going slower), so a helicopter has more lift on one end than the other. This means you have to correct for that. With a plane, if you just let go of the controls, it will actually correct itself and even out into level flight.
posted by willnot at 8:08 AM on February 25, 2005
posted by willnot at 8:08 AM on February 25, 2005
If you've never flown before and someone hands you the controls of a Cessna you will remain flying as long as you don't close the throttle or pitch the nose up to hard. If you're in a helicopter and someone hands you the controls you will most likely crash within seconds.
Also, if you're considering learning to fly one or the other, a helicopter is much more expensive to learn on.
posted by bondcliff at 8:10 AM on February 25, 2005
Also, if you're considering learning to fly one or the other, a helicopter is much more expensive to learn on.
posted by bondcliff at 8:10 AM on February 25, 2005
It's a known scientific fact that helicopters can't fly. They just beat the air into submission. Planes fly like God intended.
That being said, a helicopter has one nice property - you can hover. That really came home for me when I was siteseeing in the Southern Alps in a helicopter right next to the mountains. Like 50 feet from them. In a small plane if you're 50 feet from a mountain, you're going to be dead in 5 seconds. In a helicopter, though, you just ease back and hover. Very nice.
posted by Nelson at 8:14 AM on February 25, 2005
That being said, a helicopter has one nice property - you can hover. That really came home for me when I was siteseeing in the Southern Alps in a helicopter right next to the mountains. Like 50 feet from them. In a small plane if you're 50 feet from a mountain, you're going to be dead in 5 seconds. In a helicopter, though, you just ease back and hover. Very nice.
posted by Nelson at 8:14 AM on February 25, 2005
I've flown both, although only very briefly.
In my limited experience the helicopter was very much more difficult.
A plane was a little like driving on ice, a helicopter was like riding a motorcycle on ice while drunk.
I know, not very helpful, but the only description I could come up with.
posted by yetanother at 8:17 AM on February 25, 2005
In my limited experience the helicopter was very much more difficult.
A plane was a little like driving on ice, a helicopter was like riding a motorcycle on ice while drunk.
I know, not very helpful, but the only description I could come up with.
posted by yetanother at 8:17 AM on February 25, 2005
I think this is a pretty good description of the challenges involved in flying a helicopter.
posted by knave at 8:53 AM on February 25, 2005
posted by knave at 8:53 AM on February 25, 2005
I'm rephrasing what others have said, but I think it might be helpful to phrase it this way:
The static stability of an aircraft is its initial response when disturbed from its angle of attack (roughly, pitch), slip or bank. An aircraft with positive static stability will return towards its initial state when disturbed, like a ball in a hemispherical bowl will return to the middle of the bowl when it is pushed. An aircraft with negative static stability will continue in the direction of the disturbance, like a ball balanced atop a hemispherical mound when disturbed will roll faster and faster in the direction of the disturbance.
The dynamic stability of an aircraft is its response over time when disturbed. You can think of dynamic stability as damping. When a disturbance happens, an aircraft with positive dynamic stability will return to its original state with progressively smaller oscillations, while an aircraft with negative dynamic stability will oscillate more and more.
Thus the best-behaved aircraft is one with positive static and dynamic stability, which once disturbed will return toward its original state (positive static stability) and will reach that state and remain there (positive dynamic stability). One possible poor behavior is positive static stability and negative dynamic stability: the aircraft returns toward its original state, overshoots it, returns again, overshoots it more, and so on until it can no longer fly.
So now that we've got that out of the way: A fixed-wing aircraft's wing has inherent positive static and dynamic stability. That's demonstrated practically in a glider; without applying any power, the aircraft settles into a controlled level descent. A single-rotor helicopter has inherent negative static stability: power must be applied to correct the craft's natural tendency to continue in the direction of a disturbance. The control of that power is up to the pilot.
(There are fixed-wing aircraft which are inherently unstable, mostly jet fighters; in those cases computers manage the coordination of controls and application of power to present a stable aircraft to the pilot. Larger helicopters have the same principles applied.)
As an example of fixed-wing stability, recovery from a stall (where the angle of attack increases until the wing stops flying, causing the nose to drop, which decreases the angle of attack, which lets the wing begin flying) is an example of fixed-wing positive stability. Additionally the angle of attack will not be constant across the wing, keeping the wingtips flying even if the root of the wing is stalled, so that bank control is maintained in an incipient stall, letting the pilot (or the aircraft itself) avoid a spin. All of this works without power being applied.
There are situations in which a rotary wing exhibits positive stability, but the only one I can think of is autorotation, which isn't very good for getting anywhere.
Disclaimer: This is all working off my own understanding as a 25-hour student fixed-wing pilot with no rotary time.
posted by mendel at 9:14 AM on February 25, 2005
The static stability of an aircraft is its initial response when disturbed from its angle of attack (roughly, pitch), slip or bank. An aircraft with positive static stability will return towards its initial state when disturbed, like a ball in a hemispherical bowl will return to the middle of the bowl when it is pushed. An aircraft with negative static stability will continue in the direction of the disturbance, like a ball balanced atop a hemispherical mound when disturbed will roll faster and faster in the direction of the disturbance.
The dynamic stability of an aircraft is its response over time when disturbed. You can think of dynamic stability as damping. When a disturbance happens, an aircraft with positive dynamic stability will return to its original state with progressively smaller oscillations, while an aircraft with negative dynamic stability will oscillate more and more.
Thus the best-behaved aircraft is one with positive static and dynamic stability, which once disturbed will return toward its original state (positive static stability) and will reach that state and remain there (positive dynamic stability). One possible poor behavior is positive static stability and negative dynamic stability: the aircraft returns toward its original state, overshoots it, returns again, overshoots it more, and so on until it can no longer fly.
So now that we've got that out of the way: A fixed-wing aircraft's wing has inherent positive static and dynamic stability. That's demonstrated practically in a glider; without applying any power, the aircraft settles into a controlled level descent. A single-rotor helicopter has inherent negative static stability: power must be applied to correct the craft's natural tendency to continue in the direction of a disturbance. The control of that power is up to the pilot.
(There are fixed-wing aircraft which are inherently unstable, mostly jet fighters; in those cases computers manage the coordination of controls and application of power to present a stable aircraft to the pilot. Larger helicopters have the same principles applied.)
As an example of fixed-wing stability, recovery from a stall (where the angle of attack increases until the wing stops flying, causing the nose to drop, which decreases the angle of attack, which lets the wing begin flying) is an example of fixed-wing positive stability. Additionally the angle of attack will not be constant across the wing, keeping the wingtips flying even if the root of the wing is stalled, so that bank control is maintained in an incipient stall, letting the pilot (or the aircraft itself) avoid a spin. All of this works without power being applied.
There are situations in which a rotary wing exhibits positive stability, but the only one I can think of is autorotation, which isn't very good for getting anywhere.
Disclaimer: This is all working off my own understanding as a 25-hour student fixed-wing pilot with no rotary time.
posted by mendel at 9:14 AM on February 25, 2005
if it looses all power in the air, it will still convert downwards potential energy in to forward flight and can probably glide to a safe landing.
This is providing the mass of the plane isn't significantly greater than the lift generated by the wings/airspeed. Otherwise, you'll have a very aerodynamic brick.
If you're in a helicopter and someone hands you the controls you will most likely crash within seconds
Is this really true? Is the level of continuous user-input really that extreme? If so, it's no wonder you don't have cross-country helocopter flights (well, that and a few other reasons.)
posted by Civil_Disobedient at 10:44 AM on February 25, 2005
This is providing the mass of the plane isn't significantly greater than the lift generated by the wings/airspeed. Otherwise, you'll have a very aerodynamic brick.
If you're in a helicopter and someone hands you the controls you will most likely crash within seconds
Is this really true? Is the level of continuous user-input really that extreme? If so, it's no wonder you don't have cross-country helocopter flights (well, that and a few other reasons.)
posted by Civil_Disobedient at 10:44 AM on February 25, 2005
A plane reacts in expected ways to expected inputs. Helicopters just crash.
Actually, no. One of my sister's ex-boyfriends is a rotary-wing pilot, and won't fly fixed wing unless h absolutely has to.
One of the things he likes about helicopters is autorotation. Let's say your engine dies in a fixed-wing aircraft. You will glide to a landing, but if you can't, for whatever reason (your plane doesn't have enough lifting surface to glide, for instance) set it down safely and have enough run-out area, you will crash.
With a helicopter, you simply adjust the collective so that you're getting maximum lift out of the blades, and then as you fall the wind causes the blades to rotate, which provides enough lift. You can point yourself at an empty space and just set it down without having to worry about having a long enough, straight enough space to land in. If you're really skilled you might even be able to set the helicopter down without any damage.
Autorotation is one of the first things that student helicopter pilots, especially in the armed forces, learn.
Another misconception in this thread: You do need to adjust the pitch of propellers in fixed-wing, rotary propeller aircraft. This is one of the ways in which you slow down when you're landing, for instance...
But yes, piloting a helicopter vs. a fixed wing aircraft is akin to riding a motorcycle vs. a car. You've got many, many times the number of inputs and things to think about when you're driving rotary wing. However, they have their uses, and they make incredible platforms for some things.
posted by SpecialK at 10:57 AM on February 25, 2005
Actually, no. One of my sister's ex-boyfriends is a rotary-wing pilot, and won't fly fixed wing unless h absolutely has to.
One of the things he likes about helicopters is autorotation. Let's say your engine dies in a fixed-wing aircraft. You will glide to a landing, but if you can't, for whatever reason (your plane doesn't have enough lifting surface to glide, for instance) set it down safely and have enough run-out area, you will crash.
With a helicopter, you simply adjust the collective so that you're getting maximum lift out of the blades, and then as you fall the wind causes the blades to rotate, which provides enough lift. You can point yourself at an empty space and just set it down without having to worry about having a long enough, straight enough space to land in. If you're really skilled you might even be able to set the helicopter down without any damage.
Autorotation is one of the first things that student helicopter pilots, especially in the armed forces, learn.
Another misconception in this thread: You do need to adjust the pitch of propellers in fixed-wing, rotary propeller aircraft. This is one of the ways in which you slow down when you're landing, for instance...
But yes, piloting a helicopter vs. a fixed wing aircraft is akin to riding a motorcycle vs. a car. You've got many, many times the number of inputs and things to think about when you're driving rotary wing. However, they have their uses, and they make incredible platforms for some things.
posted by SpecialK at 10:57 AM on February 25, 2005
It's like the difference between riding a bicycle and riding a unicycle.
posted by pracowity at 12:00 PM on February 25, 2005
posted by pracowity at 12:00 PM on February 25, 2005
Let's say your engine dies in a fixed-wing aircraft. You will glide to a landing, but if you can't, for whatever reason (your plane doesn't have enough lifting surface to glide, for instance) set it down safely and have enough run-out area, you will crash.
There's enough spin on that paragraph to bring a helicopter down safely with room to spare.
Aircraft not capable of gliding are not the ones you'll encounter as a recreational pilot. The only things I can think of are fighter jets -- even an airliner makes a perfectly acceptable glider. Whatever you're thinking of, I'm not sure what the difference is between that and a helicopter pilot who doesn't nail the flare after autorotation -- a 1500 fpm landing will do a good job on your spine.
An emergency landing is an emergency landing, and sometimes you just can't find that spot no matter what you're in -- but that's not what people here have been saying. Conventionally designed fixed- and rotary-wing aircraft have different stability characteristics, and fixed tend to fly despite the pilot while rotary tend to fly because of the pilot. Power-off descent is normal procedure in a lot of general-aviation aircraft.
Another misconception in this thread: You do need to adjust the pitch of propellers in fixed-wing, rotary propeller aircraft. This is one of the ways in which you slow down when you're landing, for instance...
Whose misconception was that? Planes with retractable gear and variable-pitch propellors are called "complex aircraft" for a reason. I bet a Bell 206 is more complicated than a Robinson R22, too. Apples and oranges.
A full-pitch prop does produce drag at low speed just like a fixed-pitch one does, but reason #1 for setting propellor pitch on descent is to be prepared to go full throttle to go around. Fixed-pitch propellors land just fine without thinking of propellor pitch at all, and you could happily fly a variable-pitch propellor at full pitch for your entire flight, or never encounter a variable-pitch propellor in your whole recreational flying career. Propellor pitch is not a basic flight control.
posted by mendel at 1:32 PM on February 25, 2005
There's enough spin on that paragraph to bring a helicopter down safely with room to spare.
Aircraft not capable of gliding are not the ones you'll encounter as a recreational pilot. The only things I can think of are fighter jets -- even an airliner makes a perfectly acceptable glider. Whatever you're thinking of, I'm not sure what the difference is between that and a helicopter pilot who doesn't nail the flare after autorotation -- a 1500 fpm landing will do a good job on your spine.
An emergency landing is an emergency landing, and sometimes you just can't find that spot no matter what you're in -- but that's not what people here have been saying. Conventionally designed fixed- and rotary-wing aircraft have different stability characteristics, and fixed tend to fly despite the pilot while rotary tend to fly because of the pilot. Power-off descent is normal procedure in a lot of general-aviation aircraft.
Another misconception in this thread: You do need to adjust the pitch of propellers in fixed-wing, rotary propeller aircraft. This is one of the ways in which you slow down when you're landing, for instance...
Whose misconception was that? Planes with retractable gear and variable-pitch propellors are called "complex aircraft" for a reason. I bet a Bell 206 is more complicated than a Robinson R22, too. Apples and oranges.
A full-pitch prop does produce drag at low speed just like a fixed-pitch one does, but reason #1 for setting propellor pitch on descent is to be prepared to go full throttle to go around. Fixed-pitch propellors land just fine without thinking of propellor pitch at all, and you could happily fly a variable-pitch propellor at full pitch for your entire flight, or never encounter a variable-pitch propellor in your whole recreational flying career. Propellor pitch is not a basic flight control.
posted by mendel at 1:32 PM on February 25, 2005
As for the core question, airplanes, easily. Want proof? No autopilot in a helicopter. That might sound like a glib answer, but it's not. Airplane Autopilots go back to something like 1920, while autopilots are still the exception on modern helicopters. It's that hard.
SpecialK, you're neglecting the helicopter dead zone: too high to survive a pure drop, too low to autorotate (not enough falling time to use upward (relative to the craft) airflow to impart the spin to the main rotor that makes an autorotation landing possible).
posted by NortonDC at 4:25 PM on February 25, 2005
SpecialK, you're neglecting the helicopter dead zone: too high to survive a pure drop, too low to autorotate (not enough falling time to use upward (relative to the craft) airflow to impart the spin to the main rotor that makes an autorotation landing possible).
posted by NortonDC at 4:25 PM on February 25, 2005
Helicopters have two other problems not yet mentioned, courtesy of a friend mine recently back from crew chiefing a Huey in Iraq and who is now learning to be a commercial heli pilot:
1. Helicopters very often move in ways that are completely contrary to your normal understanding. Your body will feel like you're going up and left, but you're actually accelerating right and down. You need to be able to understand three-dimensional motion.
2. Helis, rarely, succumb to 'ground resonance', which is a very, VERY weird condition under which the helicopter, upon contact with the ground, begins resonating at a frequency, and those resonating waves amplify over time. What it feels like: the helicopter is about to fall apart. What you _want_ to do in such a situation: land quickly. What that will do: immediately destroy the helicopter in a shattering explosion of millions of bits of metal, glass and fuel, leaving a bizarrely twisted total write off of a helicopter skeleton. What you must do instead: lift off, disconnecting from the ground and stopping the vibrations, before landing again.
My friend has worked as an aircraft mechanic for some time, and believes that planes are generally safer. However, autorotation is "a parachute that you always have with you" on a heli, and a properly maintained helicopter flown by a competent heli pilot is the safety equal of any piece of temporarily lofted metal.
posted by felix at 4:44 PM on February 25, 2005
1. Helicopters very often move in ways that are completely contrary to your normal understanding. Your body will feel like you're going up and left, but you're actually accelerating right and down. You need to be able to understand three-dimensional motion.
2. Helis, rarely, succumb to 'ground resonance', which is a very, VERY weird condition under which the helicopter, upon contact with the ground, begins resonating at a frequency, and those resonating waves amplify over time. What it feels like: the helicopter is about to fall apart. What you _want_ to do in such a situation: land quickly. What that will do: immediately destroy the helicopter in a shattering explosion of millions of bits of metal, glass and fuel, leaving a bizarrely twisted total write off of a helicopter skeleton. What you must do instead: lift off, disconnecting from the ground and stopping the vibrations, before landing again.
My friend has worked as an aircraft mechanic for some time, and believes that planes are generally safer. However, autorotation is "a parachute that you always have with you" on a heli, and a properly maintained helicopter flown by a competent heli pilot is the safety equal of any piece of temporarily lofted metal.
posted by felix at 4:44 PM on February 25, 2005
This thread is closed to new comments.
The tail rotor is also slightly more complex than the rudder plane of a fixed wing vehicle.
While there can be a good number of control surfaces on a winged aircraft, basic flight operation is fairly straightforward compared to that of a helicopter.
posted by majick at 7:44 AM on February 25, 2005