As far as I understand, there are 4 seperate controls required to pilot a helicopter, none of which map to any of our conventional degrees of freedom that we think in. What this means is that it requires an inordinate amount of training and effort to be able to fly a helicopter and makes them very prone to crashing in high stress situations like war zones.
With modern computer control devices, why hasn’t the intelligence of the helicopter moved from the user to the machine?
No actual knowledge but here are my WAGS
Helicopter pilots already know how to fly helicopters. So you end up with somewhat of a solution in search of a problem (at least from a funding point of view)
Reducing the controls from the non-intuitive to control but physical to intuitive-to-control but non-intuitive may produce unpredictable results in non-standard situations, possibly moreso than in conventional aircraft
That is a good question. Helicopters would be a prime candidate for fly-by-wire systems in which the control input isn’t directly liked to any one control. I am almost sure that I have read something about this in an aviation magazine but I can’t recall or provide a cite for it at the moment.
I know that adding fly-by-wire capability to small aircraft is extremely expessive but then again, helicopters already are.
I am working at NASA on helicopters, so I feel qualified to comment.
First, the difficulty is that you make your control inputs in the nonrotating frame, and they need to get carried into the rotating frame. This is a difficult problem. The standard solution has been the use of a swashplate. This has the probelms associated with all rotating machinery, and a hell of a lot more. I have been working the last couple days on some calibration problems we have been having with one in a wind tunnel.
There are many other solutions people have been working on other than the basic swahplate. Kaman has been using trailing edge flaps on their blades for quite a while to give control, but they still use a swashplate for collective control. Other work is being done to replace the swashplate entirely using things such as active materials.
The problem with your question is that you do not realize there are several parts to it. The first is why we don’t have a different control mechanism. As I have said, we are working on them, but it doesn’t look like any of them will reduce complexity a whole lot.
The second is why we do not have computers doing a lot of the work. We do. Computers do all sorts of stability augmentation and other such things to make piloting the helicopter easier. If we were to make it any easier to fly the things, we would be taking away a lot of their capabilities. It is easier to fly a plane because a plane cannot hover, or fly sideways, or backwards, or straight down without pointin that way. Planes are getting easier to fly, but they will always be harder than cars becuase you have a third dimension to worry about.
Also, the controls are already made intuitive. Naturally, depending upon the hub configuration, pushing the stick right might take you forward and to the left.
By Kalman I assume your referring to the Kalman who invented the Kalman filter. If so, I’m in awe :D. I’ve seen several schemes for helicopter control demoed, mainly as a proving ground for various control technologies. I think a group in Japan managed to do it with fuzzy control as early as… what? late 80’s? More recently, I saw a demo by the MIT team of their model helicopters doing crazy stunts around campus. As far as I know, the essential bits are a solved problem, am I wrong?
I think just basic stuff like not moving up when you go forward would go tremendously towards making helicopter control more intuitive.
What you are suggesting would have to be a fly by wire system and I can think of a couple of reasons:
Cost. If it were possible (it may not be see point 2) it would be phenomenally expensive. IIRC the pilot does get some help in some choppers (Chinook?).
It’s a difficult task. Have you tried flying one? All the controls cause reactions that have to be countered using the other controls. For example: You apply more power+rotor-angle to get more lift - you have to counter the extra torque/turning by applying rudder - applying rudder pushes you sideways - you counter the sideways with some stick/cyclic - so now you’ve got a bit less lift so you need more power. . .
On preview I see Shagnasty sees the control interaction as a candidate for fly-by-wire, my WAG is that this would be impractical.
Oh, Shalm?? Read again what flight typed…
Oops. Helicopters have pedals not rudders. IANAHP sorry. A rudder would be a bit crap in a hover.
Don’t they already have automated control on unmanned helicopters? (Military UAVs, not hobbyist R/C helicopters) Or do those require constant control by a human operator?
Ok, possibly an ignorant question, but that’s what we’re here for isn’t it…
Helicopter controls in the videogame Battlefield Vietnam and/or Battlefield 1942 are handled with four buttons on the keyboard and a mouse, ideally with two buttons.
Specifically, W increases lift, S reduces it so you can drop quickly. A and S rotate the chopper left and right, respectively. Then you control tilt with the mouse… move the mouse forward, the chopper tilts forward; move the mouse to the right, and the chopper tilts to the right.
So, to lift off the pad and turn to the right and fly forward, as a simple example, you press and hold W, tap S a few times until you’re pointing the right direction, and then tilt the chopper forward while accelerating the blades, and you’re off.
Granted, it’s a bit more complicated in actual practice. Took me quite a lot of ‘deaths’ to get the hang of it, and I still tend to crash them rather than land.
So why not this configuration: A joystick to replace the mouse in the cockpit, add buttons for weapons etc if needed. A pedal for acceleration/lift, and any number of things could be used for rotation… at worst, a steering wheel.
I know if my computer at home can simulate the performance of the entire battlefield and still fly this chopper around, the Air Force can stick one into their choppers and do the same thing.
So why don’t they?
One possible issue may be equalizing all those forces Small Clanger mentioned… but that’s what we’ve got computers for? But the computers would need sensors to know what to do… and sensors are expensive. Still, on a $15,000,000 (to pull a number out of my rear) chopper what’s another $500,000?
The controls have improved a lot.
Older helicopters have a twistgrip on the collective control that works the throttle. So you have to control:
side to side cyclic (like ailerons)
fore and aft cyclic (like elevator) both of these two on the stick
tail rotor (like rudder) worked with foot pedals
collective (lift control) worked with the left hand on a parking-brake type lever.
throttle - twistgrip on the collective control.
Modern helicopters have constant-speed rotors. The throttle is worked automatically by a governor, that keeps the main rotor disk spinning at a constant speed, regardless of the load you put on it (e.g. by using the collective control to call for extra lift).
There’s also the possibility of mixing - say collective into tail rotor, so that as you call for more lift, the tail rotor is adjusted automatically, without the need for adjusting the pedal position.
As someone already said, you don’t want to change the controls too radically, as pilots are already used to them. The hardest part of flying helis, is NOT just dealing with the primary controls though.
As has been mentioned, much is done for you on modern helicopters, though if you buy a super cheap one (in helicopter terms) you are still on your own. Yes, UAV helicopters are in complete control of themselves, and test flight have been done where it takes off, flies a course, and then lands on its own.
In the now defunct Comanche the control system was remarkably easy for a helicopter and everything was computer controlled. The problem with having so much done by the computer is that you have to account for limits of the physical system which could be too conservative when in combat and the pilot’s life depends upon pushing those limits.
If thrust was always modified to maintain altitude no matter what attitude you have, you would severly limit the amount of attitude, and therefore forward acceleration, you could obtain. In fact, in order to try a hard maneuver in a helicopter that was making these corrections for you, you would have to think around it and apply NEGATIVE collective, in effect telling the computer that it was OK to lose altitude. This is far more unintuitive than anything currently in a real helicopter.
Phnord Prephect, if a real helicopter was as simply as the helicopter in your game, my calculator could fly it. They simplify it and do not include the interactions, rather than have to account for them.
Shalmanese, here is a Kaman.
A couple years ago I saw on The Discovery Channel a new helicopter design which essentially eliminates the need for the very vulnerable tail rotor. The tail boom is simply shaped like a vertical wing and the constant downdraft blowing across it from the main rotor counters the torque of it.
There’s also a small vectored nozzle where the tail rotor usually is, but this is just for in-flight control. The show said this was a major design improvement and would soon be universal but I’ve not scene it since.
Paging Johnny LA…
:eek: 
I love the SDMB
Helicopter private pilot checking in. 
Flight’s a hard act to follow, though. 
Helicopters have a cyclic stick, a collective lever, a throttle, and anti-torque pedals. An airplane has a control stick (or yoke), a throttle, rudder pedals, and often a propeller pitch control. Pretty much the same, really.
Not really. A helicopter isn’t any “harder” to fly than an airplane; just a little different. The hardest part of flying a helicopter is hovering. It’s also the most necessary, which is why its taught first. Once you have hovering down, the rest is cake. A friend of mine was a bit envious because most people in her squadron took about 15 hours to hover; while I was hovering (shakily, but still controlling it) by the end of my first lesson.
The thing to remember about helicotpers is that they’re inherently unstable; unlike an airplane, which is normally at least neutrally stable. (Most civilian aircraft have positive stability.) This means that the pilot must make constant, minute control inputs in order to keep the aircraft stable. What you find out quickly is that if you try to “chase” the helicopter, you’ll always be behind it. Instead, don’t think about flying it; your muscles will make the proper control inputs subconsciously. You “fly it by not flying it”. Kind of Zen.
There’s really no need. As MMI points out, helicopter pilots already know how to fly them. And then there is the expense. Helicopters are much more expensive than airplanes. A Robinson R-22 goes for around $200,000. It carries two people at about 100 knots (87 being the most efficient speed) using the same engine as a Cessna 172 – which carries four people at around 120 knots and has about twice the range.
Most Lycoming-powered aircraft have Time Between Overhauls (TBO) of 2,000 hours. Aircraft in commercial service, including rental, must be inspected annually and every 100 flying hours. A Cessna 172 will have problems repaired, and the engine will be rebuilt. An R-22 will have the engine rebuilt, the transmission rebuilt, the old main- and tail- rotor blades trashed and new ones installed, as well as any other “squawks” fixed. Imagine if you had to discard a Cessna’s wings every 2,000 hours! That’s basically what you’re doing with a Robbo. A Schweizer 300CB needs its rotor blades replaced every 4,000 flying hours – but there are three of them instead of two.
Suffice it to say that adding fly-by-wire to an R-22 would be adding expense and, more importantly, weight to an already-expensive machine that is already carrying as much as it can.
and
First things first. In an airplane, you also have to adjust different controls when you move one. Take a left turn, for example. In addition to turnint the yoke or stick to the left, you also need to add left rudder so that you don’t enter a “skid”. Once you’re banking, your lift vector is no longer straight up, so you need to add elevator. Add elevator, and you slow down; so you have to add throttle. (Well, you don’t have to add throttle unless you want to maintain a constant airspeed in the turn.) It’s all interconnected. So there’s really not that much difference. (Oh – I hold a fixed-wing rating too.)
But what about “moving up when you go forward”? Not sure what you mean here. If you push the cyclic forward without doing anything else, you’re going to go down because the lift vector has shifted. You need to add throttle to maintain your altitiude or go up. (You also need to add more anti-torque pedal because you’ve added power.) But the thing is that if you push your cyclic forward, the swashplate doesn’t tile forward. It tilts starboard. This is because of recession. A force applied to a rotating mass manifests itself 90° later in the direction of rotation. Moving the cyclic forward tilts the swashplate to starboard. That is, there is a “downward force” on the right edge of the rotor disc. Because of precession, the rotor blades reach their lowerst point in front of the helicopter. The rotor disc tilts forward, resulting in the helicopter moving forward – even though the swashplate tilted right.
But the pilot doesn’t have to think about that. Stick forward, go forward. And in flight, you don’t use the pedals as you would in an airplane to make a coordinated turn. You can, if you want to be anal about it and make it “perfect”; but I’ve found it to be like playing a big video game. Just point the cyclic where you want to go. Of course the pedals can be used to yaw; but their main function is to control the anti-torque rotor, which just counteracts the torque of the engine.
Not just on older helicopters. On turbine helicopters (which I have not had the pleasure of flying) still have their “throttles” (in a fixed-wing turboprop, I think they’re called “condition levers”) on the cyclic stick. On piston-powered helicopters, that’s where the throttle still is. There are governors. They keep the engine RPM approximately appropriate to the rotor RPM. You still have to jocky the throttle though. You can also turn the governor off. In training (in the R-22) I wasn’t allowed to use the governor; I had to adjust the throttle (and RPM and manifold pressure) manually. It got to the point where it was just weird to use the governor. I learned to fly in Southern California where it’s often HOT. With two heavy guys in a little R-22, I got pretty good at “milking the throttle” on a hot day to keep the RPM and manifold pressure where it belonged.
Not in my experience.
You may be thinking of the McDonald Douglass NOTAR. The NOTAR has a “can” at the end of the tail boom that can vector thrust that is produced by a fan connected to the engine. This is similar to adding more or less anti-torque from a conventional tail rotor. The anti-torque thrust, however, comes from the Coanda Effect. The fan inside of the fuselage sends air out through a slot on the boom that causes air to “stick” to the boom – in effect, making it into an airfoil.
The NOTAR tail is less susceptible to damage; but it’s biggest attribute is noise reduction. Tail rotors spin very fast, and so they make a lot of noise. By elimiating the tail rotor, the aircraft is much quieter.
I think flight and Johnny L. A. have covered the OP. But I have to ask:
What is a space administration doing with helicopters?
Hold onto your hat, buddy, NASA flies not only helicoptors but fixed wings, balloons, and I think a blimp or two as well. They do a lot of research into flying of alll sorts, not just the space kind.
I met a Blackhawk pilot at an airshow once, and he told me that his helicopter did use fly-by-wire and computer management. (pilot control input goes to a computer, which sends the appropriate signals to manipulate the control surfaces.) I thought of a follow-up question later, but haven’t had anyone to ask until now, with flight and Johnny L.A. in this thread.
In a helicopter with a computer control system, does the computer account for the coupled forces (extra power means more anti-torque, etc.) on its own, or are pilots so accustomed to those effects that the computer still requires those inputs?
Are you saying these (engine & rotor) are not directly connected? Is there a slush box in there? Interesting.
Manifold pressure? I know what manifold pressure is, but what are you adjusting exactly? And why? Can you expand on this?
NASA and helicopters?
Yup! Helicopters on Mars