- 2 days ago
For educational purposes
Two years after the first crewed flight, the Wrights mastered control sufficiently to fly the first circle – a major aviation advance that went almost unnoticed.
By World War II, the first hydraulically boosted controls were invented, enabling pilots to fly aircraft weighing more than 100,000 pounds without the muscles of a co pilot.
Once digital signals succeeded in maneuvering spacecraft, computerized fly-by-wire technology for aircraft was not far behind.
Featured Aircraft:
- Wright Flyer
- Beachey Little Looper
- Vought F4U Corsair
- Vought F-8 Crusader
- Sikorsky S-76 Shadow helicopter
Two years after the first crewed flight, the Wrights mastered control sufficiently to fly the first circle – a major aviation advance that went almost unnoticed.
By World War II, the first hydraulically boosted controls were invented, enabling pilots to fly aircraft weighing more than 100,000 pounds without the muscles of a co pilot.
Once digital signals succeeded in maneuvering spacecraft, computerized fly-by-wire technology for aircraft was not far behind.
Featured Aircraft:
- Wright Flyer
- Beachey Little Looper
- Vought F4U Corsair
- Vought F-8 Crusader
- Sikorsky S-76 Shadow helicopter
Category
📚
LearningTranscript
00:01Hi, I'm Neil Armstrong. Join me for an adventure through time.
00:53I'm Neil Armstrong.
00:57On December 17th, 1903, at Kitty Hawk, North Carolina, the Wright brothers demonstrated that man was capable of powered flight.
01:09Their Wright flyer ascended and flew straight. They did not try to turn.
01:16By two years later, they had mastered control sufficiently to fly the first complete circle.
01:22Where other aircraft pioneers had envisioned the airplane as a ship, navigating through air instead of water, with only a
01:32rudder for steering,
01:34the Wrights invented three-axis control, giving the aircraft the ability to climb, descend, and turn by banking.
01:42Ever since, aircraft control has remained basically unchanged, a tribute to the Wright brothers' genius.
01:55In September 1905, over Huffman Prairie in Ohio, Wilbur Wright flew the first circle in the Wright Flyer 3.
02:03It was a major aviation milestone that went almost unnoticed.
02:09Through methodical trial and error, building on their early experiments with gliders,
02:14the Wrights had devised a control system using wing warping, a hinged tail rudder, and forward elevators.
02:22The pilot lay in a hip cradle.
02:24By shifting his weight to the side, he caused the outer trailing edges of the wing to be pulled down
02:30on one side and up on the other,
02:32causing the aircraft to roll.
02:36Side slipping was controlled by the rudder.
02:39This was interconnected with wing warping, so the pilot could make a smooth turn with one hip movement.
02:45The pilot tilted the elevator surfaces up and down with a stick to control pitch.
02:51The Wright Flyers had the necessary control to bank, turn, circle, and easily fly for half an hour at a
02:59time.
03:04By 1911, when the Little Looper was built, ailerons had replaced wing warping as the state-of-the-art control
03:10for banking.
03:12Norman Swellson explains the control system of this unique pioneer aircraft, the Beachy Little Looper.
03:19The Beachy had a little different control in that we did not use our feet as we do in a
03:26conventional airplane.
03:27Our feet work the rudder pedals, and in this case, they just sit idly by it.
03:32We swing them along kind of neat.
03:34We do have the conventional pullback on the stick to bring the nose up and forward to drop the nose.
03:43We have a rudder situation where it would normally be in the rudder pedals, has been put in the wheel.
03:49And by turning that to the left, I can get a left turn out of the aircraft or a right
03:54turn appropriately.
03:55So we can now coordinate on the stick alone.
03:59We've got a climb out with a right turn or a climb out with a left turn.
04:04However, we have no wing control.
04:07So we've got to get our aileron moved here.
04:11The designers put it into body English.
04:13And if you'll notice, when I lean to the right, I will activate the right aileron along with the left
04:19doing the opposite.
04:20And when I move to the left, the left aileron is activated with the right doing the opposite.
04:25So that was the principle.
04:27Full lean to the left for a left bank.
04:30Full lean to the right for a right bank.
04:32So our body English then, thusly, for a climbing right turn, would be something like this.
04:38Pulling back on the stick, leaning a little bit, and making a coordinated turn all at the same time.
04:43Nose down attitude in a downward bank would be this way.
04:47Straightening it out, bringing it back to neutral, still diving, pulling it back to a neutral position,
04:53leveling out, bringing the nose up, and flying straight off.
05:03By 1912, almost all airplanes used the basic arrangement of aerodynamic control surfaces most often used today.
05:11Ailerons, elevators, and rudder moved by rudder pedals and a stick, or control column.
05:22When the pilot lowers the elevators by pushing forward on the stick, airflow is deflected downward, and lift on the
05:29tail increases.
05:31This rotates the aircraft tail up and nose down.
05:36The rudder acts in a similar way, deflecting the air flow to the right or left, pushing the rear of
05:42the aircraft in the opposite direction.
05:47The ailerons act together in opposite directions.
05:50One rises while the other is lowered.
05:52They decrease the lift on one wingtip while increasing it on the other, causing the aircraft to roll.
05:59Movement in these three directions is all interrelated, so the use of control surfaces to fly the aircraft must be
06:06coordinated.
06:07This is evident in one of the most treacherous situations a pilot can encounter, a stall spin.
06:16By 1915, flyers at Farnborough in England first demonstrated spin recovery.
06:22Their technique involved simply centralizing the controls.
06:26The aircraft would then find its equilibrium.
06:29Later, more aggressive techniques were used to recover from spins.
06:33The pilot pushed the stick forward and applied controls opposite to the spin.
06:42During World War II, the first hydraulically boosted controls were invented.
06:47They worked like power steering in an automobile.
06:50Another result of this aviation development.
06:54For pilots used to manhandle heavy bombers and fast fighters,
06:58innovations like servo tabs and hydraulically boosted controls were revolutionary.
07:05For the first time, it was possible to control an aircraft weighing more than 100,000 pounds with a single
07:13pilot.
07:14Flying at speeds approaching 500 miles per hour no longer involved a wrestling match with stick and rudders.
07:21The controls now handled as easily as they did at low speed.
07:29From the early days until after World War II, flight control systems were operated manually.
07:37As aircraft became larger and faster, the forces on the control surfaces increased.
07:43Large aircraft required the muscle of two strong pilots working together.
07:48When the Barling Bomber triplane first flew in 1923, it was one of the largest airplanes in the world.
07:55But it was underpowered and difficult to maneuver.
07:59Help for large aircraft came in the form of servo tabs.
08:04These are small, easy-to-move flaps attached to the trailing edges of the control surfaces.
08:10As the pilot moves the stick, aerodynamic forces on the small tab help move the large control surface into the
08:17desired position.
08:21Hinged trim tabs work in a similar way to balance the forces on the airplane in flight.
08:26When they are set by the pilot, the aerodynamic forces on the trim tabs hold the control surfaces in the
08:32desired position for stable flight.
08:39This eased the strain on pilots.
08:42Trim tabs could be easily adjusted with hand wheels in the cockpit.
08:48Servo tabs first began to appear in the 1920s.
08:52By World War II, many aircraft were fitted with both servo tabs and trim tabs.
08:58One of these was the F4U Corsair, a formidable fighter.
09:03Its distinguished combat record in World War II owed much to its speed and maneuverability, thanks in part to the
09:10use of servo tabs.
09:16We're here with Steve Hinton, who flies this Corsair.
09:21Steve, tell us about the F4U controls.
09:23Well, we're standing behind here, the airplane, looking at the elevator.
09:27You'll look at this servo trim tab.
09:29You can see how the servo tab is connected, fixed to the horizontal, and fixed to the trim tab.
09:35But you can see as the elevator goes up, trim tab goes down, and vice versa.
09:40Elevator goes down, trim tab goes up.
09:42And what the servo tab does is it lightens the control, the stick force on the pilot.
09:46As he pushes down through the linkage, you can see how the trim tab sticks up.
09:51And this really reduces the stick forces that a pilot needs to exert on the controls.
09:58It's especially effective at high speed.
10:01Never flown a Corsair without a servo tab because they all had them, but I could imagine without this device
10:05right here, the stick would probably in pitch be real heavy.
10:09Controls on a Corsair are really balanced nice, and this is the reason through the design.
10:15As aircraft became larger and faster, the next development was hydraulically boosted controls.
10:23During World War II, autopilots came into use, and they required ways of moving the control surfaces without the pilot's
10:31involvement.
10:32Systems were developed using pneumatic and hydraulic pressure.
10:36The next step was to use these hydraulic systems to help the pilot move the controls of very large or
10:42very fast aircraft.
10:44Like powered steering and brakes in an automobile, hydraulic pressure lessens the brute force needed to move the controls.
10:52By the mid-50s, hydraulically boosted controls had reached their limits.
10:57Most large, fast aircraft were being equipped with PFCs, powered flight control systems.
11:05In the XB-70, for example, the huge control surfaces were moved by hydraulic systems.
11:10The pilot moved his cockpit controls.
11:14In response, highly geared power hinge actuators with operating torque capability of 750,000 pounds per square inch controlled the
11:23movement of the large rudders.
11:26In these systems, the pilot's cockpit controls do not directly move tabs or control surfaces.
11:32The pilot's mechanical input is received by a control unit.
11:36This converts the input to hydraulic output, which then moves the control surface the correct amount.
11:44As powered flight control systems develop, the linkage between the pilot and the control surfaces increasingly became electrical.
11:53Fly-by-wire technology lay on the horizon.
11:59Fly-by-wire technology was used successfully for maneuvering spacecraft in flight.
12:05In the early 1970s, fly-by-wire research for aircraft was conducted in this F-8 Crusader using digital signals
12:15processed by a surplus Apollo spacecraft computer.
12:20Fly-by-wire means exactly what it says.
12:22The pilot is connected to the control surfaces by electrical wiring only, not mechanical linkage.
12:29In a digital system, when the pilot moves the stick, an electrical signal is sent to a computer, which sends
12:37a message to the servo directing the control surface position.
12:41The pilots were a little leery of having their safety completely dependent on electrical connections.
12:52This modified Vought F-8 Crusader first flew on May 25th, 1972.
12:58It was the flying testbed for fly-by-wire, a technology that would not only radically revolutionize aircraft design, but
13:06also the way pilots interacted with their aircraft.
13:10In a fly-by-wire system, the pilot's actions on the controls send a message to a computer.
13:16The computer determines just what movements of the control surfaces would accomplish what the pilot wants.
13:24Like anti-lock brakes on a car, the computer performs the pilot's wishes in the most effective way, sometimes with
13:31methods the pilot would not be able to perform.
13:34Fly-by-wire systems also provide a high level of aircraft stability.
13:40Sensors detect any divergence from the desired flight path, and the computer instantaneously calculates the needed adjustments to the flight
13:48surfaces.
13:50Neil spoke with Cal Jarvis, who was project manager for NASA's original fly-by-wire research program begun during the
13:581960s.
14:00We're here with Cal Jarvis, who was the project manager on the original digital fly-by-wire system.
14:09Cal, tell me, why was there interest in electrical control systems in the first place?
14:17There are a lot of advantages to electrical, electronic systems, digital fly-by-wire systems, mainly because they can be
14:22made more reliable,
14:23they can be made more flexible in terms of programmability.
14:29Also, they can be made lighter, so you can take the weight advantages and trade that off into performance improvements
14:36on the aircraft.
14:37So there's a lot of interest, I think.
14:38As you started this first digital fly-by-wire system, what were the challenges and what were the problems in
14:46getting it going?
14:48Really overcoming, I think, some of the mental attitudes at that point in time.
14:54There's a lot of feeling in the early 70s when the F-8 fly-by-wire, digital fly-by-wire
14:59aircraft was first flown.
15:00As to whether or not you could actually design and develop a digital system that you could operate.
15:06To put a digital computer between the pilot and the atmosphere, the aerodynamics there, would be a tough thing to
15:11do.
15:12Ironically, you started using some old space hardware, and one of the benefits came back to space.
15:21Initially, the first goal on the F-8 program here was really to demonstrate that you could build a reliable
15:29and a feasible digital fly-by-wire system
15:32to operate in an aircraft environment.
15:34And we didn't want to spend a lot of money initially in doing that, and it turns out the Apollo
15:39equipment was available.
15:40The Apollo program was kind of winding down at that time.
15:43And there was equipment available, and it was extremely reliable equipment.
15:48So we ended up using the Apollo guidance and navigation computer.
15:52We also used the display and keyboard assembly, which is this unit on top here.
15:59The fact is, this is the actual display and keyboard assembly that flew in Apollo 14.
16:03Oh, really?
16:04We were able to acquire this and interface it into the F-8.
16:07About that same time frame, the space shuttle made the decision to go to a digital fly-by-wire system
16:13on the orbiter.
16:14And we joined with the program office there and laid out kind of a joint program where we, in essence,
16:20used the same digital computers that were going to be developed and used on the space shuttle orbiter.
16:26And that allowed us to get some early flight experience and actual operational environment in support of the space shuttle
16:33development.
16:34Also, by doing that, we were able to evaluate a lot of the software that was developed for the space
16:39shuttle orbiter.
16:46Today, fly-by-wire technology is being put to use around the world in a variety of aircraft.
16:54Military fighters like the General Dynamics F-16 and the Northrop F-A-18 use fly-by-wire control systems.
17:03Airbus industry has taken the bold step of incorporating fly-by-wire technology in a commercial airliner, the A-320.
17:13Sikorsky Aircraft is exploring the technology for use in helicopters in its fly-by-wire testbed, the Sikorsky Shadow.
17:21Neil had the opportunity to discuss the shadow with engineer Russ Stiles and to fly this unique machine.
17:28Russ, as you pointed out in flight, when the stick's over here on the right side, it really opens up
17:35the center of the panel here for instrumentation.
17:38Right, that's one of the benefits of having not only the fly-by-wire system, but having the sidearm control
17:44system.
17:45This is very valuable real estate, as you know, in front of the pilot.
17:49And you want to put your primary displays there, not some mechanical control system.
18:05You want to put your primary keyboards into the car?
18:14This is very valuable.
18:17It's very valuable.
18:17It's very appropriate.
18:18Please play along the vehicle on top of the vehicle that you can access the vehicle from the sides.
18:22The vehicle has the vehicle of a馬 and most powerful vehicle while you are supposed to be able to make
18:26it.
18:51With fly-by-wire capability, the world opens up to you
18:56in terms of what kind of options can you give the driver of this machine.
19:00You can really automate a lot of the things that he was doing in the old days very manually.
19:15Does it require more complexity in the machine replacing the mechanical with more electrical components?
19:24There's a lot of mechanical components that come out.
19:26As you can imagine, all the pushrods and the cables that typically typify a mechanical system.
19:33And yes, I will say that more computers go in.
19:36But the computers are there for the redundancy required to achieve reliability on the same level as a mechanical system.
19:47The way I look at it is, it's been a marriage.
19:50The mission requirements have been sitting over here waiting for computers.
19:56The ability to go out and fly at night, fly very low level where we were,
20:01napa the earth, in bad weather conditions, has been waiting for computers to come along
20:06to be able to automate many of the functions.
20:09Fly-by-wire then comes in and marries together those two.
20:14The redundancy of the computers and the wires comes in and marries with the functionality that it gives you.
20:21And it's a natural evolution of control systems.
20:24We're really doing things with helicopters now that 15, 20 years ago you could not have done.
20:30You're right, absolutely.
20:32The mission environments that we live in and the types of missions that the pilots are able to do now
20:39are much more complicated than those long ago.
20:43Night time is a friend to today's pilots, whereas before it was really something we wanted to shy away from.
20:51Now that's where they prefer to fly.
20:53Because they're safer from the enemy?
20:55Absolutely.
21:10In life, control's important.
21:12In aviation, control's imperative.
21:15Join us again next time for First Flights.
21:33To be continued!
Comments