nickbbu
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Steering The Aircraft, How It's Done?

Sun Dec 14, 2008 7:25 pm

It may sound stupid to many of you but I don’t know how a plane makes its way around the airport. Even though I flew almost 80 times I never asked myself this question until now.

Is there some kind of steering wheel (I bet there isn’t), it’s done by pedals or by joystick (for Airbus) ?
Can you please explain me how it’s done? Is it different for every aircraft type?

Thank you in advance.
Nick

[Edited 2008-12-14 11:25:58]
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David L
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RE: Steering The Aircraft, How It's Done?

Sun Dec 14, 2008 7:36 pm

Quoting Nickbbu (Thread starter):
Is there some kind of steering wheel (I bet there isn’t)

Don't make that bet.  

On the airliners you're likely to fly in, steering on the ground is accomplished by turning the nose-wheel with a with a tiller (i.e. a "steering wheel"). You can see one on the FO's side here, just outboard of the sidestick:


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The rudder pedals also give a small amount of nose-wheel steering, useful during take-off and landing so you don't have to switch between tiller and pedals in the middle of critical phase.

[Edited 2008-12-14 11:38:43]
 
flyf15
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RE: Steering The Aircraft, How It's Done?

Sun Dec 14, 2008 8:54 pm

As David L said, many aircraft are equipped with a tiller, commonly only on the captain's side but sometimes on the FO's side as well. It acts as a steering wheel for the nose wheel on the ground.

On the CRJ, the tiller provides approximately 70 degrees in either direction of nosewheel steering while the rudder pedals provide only 7 degrees (which is enough to make minor corrections to steer you down a straight line, such as down the runway during takeoff and landing, but not enough to make any significant turns).

It can be seen in this picture just to the left of the captain's left knee, below the checklist and by the water bottle.


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DeltaGuy
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RE: Steering The Aircraft, How It's Done?

Sun Dec 14, 2008 9:13 pm

Small GA aircraft and military fighters use rudder pedals for the entirety of their steering, the vast majority having nosewheel steering as well as differential brakes available for taxi.

Larger transport category aircraft will use their nosewheel steering through the tiller, it could be a nice wheel or lever on the Captain's side, even down to a rudimentary little bar like on the Shorts 360.

One of the hardest planes I've ever flown/taxiied was any Yak or CJ-6 type aircraft, it has just rudder pedals, and the brake is actuated by a lever on the stick- in order to turn, you have to put in just the right amount of pedal, and just the right amount of squeeze on the stick- tricky at the very least, at least at first.

DeltaGuy
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roseflyer
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RE: Steering The Aircraft, How It's Done?

Sun Dec 14, 2008 10:19 pm

To add some more information, steering is controlled by either cables or electrically. There are usually the two inputs of rudder pedals and the tiller. As previously stated, 7 degrees is usually about as much as the nose wheel will turn based on rudder pedal input. The amount rotated is designed to give a smooth transition upon landing from aero control via the rudder to the steering. The tiller is not to be used on the runway except in emergencies after the plane is lined up.

In cable driven aircraft, the cable in the tiller goes to a steering assembly which will port pressure to either of two actuators located on the nose wheel. The actuators are hydraulically powered and can rotate the nose wheel roughly 70 degrees (varies based on the airplane). Electric steering control usually has only electric control of the actuators that are still hydraulic. A more innovative way is to have electric motors move the nose wheel.
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Starlionblue
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RE: Steering The Aircraft, How It's Done?

Sun Dec 14, 2008 11:00 pm

The word "tiller", just like many words in aviation, has a naval background. Tillers are the steering controls on ships and boats.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
David L
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RE: Steering The Aircraft, How It's Done?

Mon Dec 15, 2008 1:51 am



Quoting Starlionblue (Reply 5):
The word "tiller", just like many words in aviation, has a naval background.

And there I was thinking it was named after the notorious Hun.
 
jetstar
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RE: Steering The Aircraft, How It's Done?

Mon Dec 15, 2008 2:05 am

Some small general aviation airplanes do not have any direct nose wheel steering, the nose wheel is free casting and steering is done by using differential braking. One time I tried to taxi a Grumman Yankee with just one brake from its tie down to our shop, I got about 100 feet and stopped because I could not control the airplane so I went and got a tow bar and a tug to tow the airplane to the shop.

On my Cessna 150 like all single engine Cessna’s steering is done through the rudder pedals and differential braking. The nose wheel is connected to the rudder pedals by spring tubes which allows you to go past the normal steering range from the rudder pedals by using differential braking. By locking up one wheel brake and you can almost pivot around on the locked up wheel. It takes differential braking from the other side to get the nose wheel to straighten up because the nose wheel is beyond the rudder pedal range. I have taxied my Cessna and other Cessna’s with one brake out, it can be done.

One nice thing about Cessna’s is the nose wheel strut has a self centering cam internally so when the nose strut is extended after take off the nose wheel is centered straight. When making a cross wind landing using rudder and opposite aileron the nose wheel will be straight with the runway.

On most single engine Pipers the nose wheel is directly connected to the rudder pedals and will deflect with use of the rudder. So when making a cross wind landing the nose wheel will be at the same angle as the rudder and when the nose wheel comes down you will start to make a turn on the runway until you release the rudder. On a lot of older single engine Pipers, toe brakes were an option and the only way to operate the brakes was a bar we called a Johnson bar which was just below the instrument panel, when you pulled up on the bar it operated both brakes so there was no differential braking. To set the parking brakes you engaged a ratchet lock to hold brake pressure.

On the Lockheed JetStar nose wheel steering was done strictly with the nose wheel steering wheel located on the Captains side panel.


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Unlike airliners, there was no connection to the rudder pedals for steering so on takeoff the left seat pilot had to use the nose wheel steering with his left hand until 80 knots when the rudder became effective and operated the power levers with his right hand initially bringing the power levers up to about the take off power setting and then lowered his hand and the right seat pilot then made the final power adjustments.

The right seat pilot had to hold aileron in if we were taking off with a cross wind and kept forward pressure on the control wheel to hold the nose down so the nose wheel steering would be effective and would gradually ease up on the controls as we approached 80 knots at which time the left seat pilot took over the control wheel, all while manually adjusting the takeoff power on 4 engines and scanning 24 engine gauges and making the 80 and 100 knot, V1 and Vr speed calls.

On landing the right seat pilot had to roll in aileron if needed and hold forward pressure on the control wheel because the left seat pilot went over to the nose wheel steering once the nose wheel was on the runway and the reversers were deployed.

On the JetStar when making tight turns the nose wheel steering wheel turned way beyond the angle you could turn your wrist so you had to use your fingers and walk the steering wheel in the direction you wanted to turn while not letting go, because you could not easily reach the wheel with your right hand to hold it in place while you moved your left hand, it took a little practice to get used to steering the airplane on the ground.

On the turboprop Gulfstream 1 and most G2’s, nose wheel steering was done with a straight small bar called a tiller bar. It was difficult to make slight adjustments while taxing because of the sensitivity of the tiller bar, so on the G2 an aftermarket company developed a steering wheel with a slight gear reduction and got an STC for it. After a number of companies bought this STC, Gulfstream then adapted it to all future production and dumped the tiller bar. If I remember back from my G2 days, like the JetStar there was no connection between the rudder pedals and the nose wheel steering

Unlike the airlines, with most corporations the left seat pilot always flew the airplane and normally both pilots were rated on the airplane and they would swap seats every leg.
 
KELPkid
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RE: Steering The Aircraft, How It's Done?

Mon Dec 15, 2008 4:57 am



Quoting Jetstar (Reply 7):
I have taxied my Cessna and other Cessna’s with one brake out, it can be done.

Yeah, but stopping ain't pretty with one brake out. I landed a Centurion once at CUU and discovered that the right brake wasn't working on our landing roll when we started veering off to the left (well, that and the right brake mushed all the way to the floor just like when you loose the brakes in the car  Wink ). Our landing roll became very long...

Trying to find a GA mechanic at a Mexican airport on a Saturday (when you barely speak Spanish  Smile ) is an interesting exercise...
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Starlionblue
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RE: Steering The Aircraft, How It's Done?

Mon Dec 15, 2008 6:21 am



Quoting Jetstar (Reply 7):
On the JetStar when making tight turns the nose wheel steering wheel turned way beyond the angle you could turn your wrist so you had to use your fingers and walk the steering wheel in the direction you wanted to turn while not letting go, because you could not easily reach the wheel with your right hand to hold it in place while you moved your left hand, it took a little practice to get used to steering the airplane on the ground.

Don't many tillers have a little "stick" that protrudes from the wheel (like some forklifts)? So you can grab the stick and spin, as it were.


Quoting David L (Reply 6):
Quoting Starlionblue (Reply 5):
The word "tiller", just like many words in aviation, has a naval background.

And there I was thinking it was named after the notorious Hun.

  

[Edited 2008-12-14 22:27:59]
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Finkenwerder
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RE: Steering The Aircraft, How It's Done?

Mon Dec 15, 2008 7:54 am

Large Aircraft also employ Body wheel steering which turns in oposition to the nosewheel direction and in the the case of the A380 utilises the last unbraked bogey pair in either Body gear.
 
jetstar
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RE: Steering The Aircraft, How It's Done?

Mon Dec 15, 2008 2:57 pm



Quoting Starlionblue (Reply 9):
Don't many tillers have a little "stick" that protrudes from the wheel (like some forklifts)? So you can grab the stick and spin, as it were.

The nose steering wheel on the Lockheed JetStar is to small to have a knob on it. Although the nose wheel steering is basically power steering, because it is hydraulic powered, it is not as light to the touch on the wheel as would be on a car, you had to hold it fairly tight in a sharp turn and if you let go of it to reposition your hands, the steering wheel would start to center itself, so that why I said you had to walk your fingers over the wheel as you turned it beyond the ability of your wrist.

For normal taxiing, you didn’t have to hold it real tight but you had to keep your hands on the wheel to prevent the airplane from drifting.

Our normal procedures was to start the 2 inboard engines, #2 & 3 and taxi out on those, the right left pilot would start these engines, as we got close to the take off position, the right seat pilot would start the remaining engines, #1 & 4. This sometimes led to too many arms getting in the way.

Because the left seat pilot had his left hand on the steering wheel and his right hand on the power levers during taxiing, the right seat pilot had to use his right thumb to press and hold in the start button on the overhead panel and when the engine reached 10% rpm, use his left hand to move the power lever up out of the idle cut off position to idle to introduce fuel and ignition to the engine, while still holding in the start button until the engine reached about 50% rpm while still keeping his other hand on the power lever and monitoring the rpm and exhaust temp gauges for any signs of a hung or hot start, which meant pulling the power lever back to idle cut off to immediately shut the engine down to prevent major damage to the engine.

Starting # 4 was easier, the power lever was on the right seat pilot side, but starting #1 meant reaching under the left seat pilots arm to reach the power lever, most times the left seat pilot just moved his right arm up enough so I could reach the #1 power lever.

During taxiing, especially for the first flight of the day, there were many hands flying around the cockpit, usually the right seat pilots as we went through the pre-take off checklist, setting checking and testing systems, starting the remaining engines and shutting down the APU, which was above and behind the right seat pilots head. If I remember correctly the pre-take off check list had about 40 items, some that could not be done until all the engines were running, like checking all the reversers by extending them, and this continued until we were cleared to taxi into position and hold or cleared for takeoff when the final 4 items were completed, pitot heat on, strobes on, aux hydraulic pump on and transponder on.

Once we started our take off run, my eyes never left the instrument panel, I had to set the final power settings and monitor 24 engine gauges while watching the airspeed indicator for the speed call outs while holding the control wheel until 80 knots. Sometimes when we had a passenger in the jump seat I would joke to him as we lifted off are we off the ground yet.


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2H4
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RE: Steering The Aircraft, How It's Done?

Tue Dec 16, 2008 5:54 pm



Quoting DeltaGuy (Reply 3):
Larger transport category aircraft will use their nosewheel steering through the tiller

Some Russian aircraft place the tiller for nosewheel steering right on the yoke:


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Quoting Jetstar (Reply 7):
One time I tried to taxi a Grumman Yankee with just one brake from its tie down to our shop, I got about 100 feet and stopped because I could not control the airplane so I went and got a tow bar and a tug to tow the airplane to the shop.

Next time, just for a challenge, you should see if you can get from point A to point B using 90s for turns toward the good brake and 270s for turns toward the bad one.  Smile

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Mastropiero
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RE: Steering The Aircraft, How It's Done?

Tue Dec 16, 2008 6:24 pm

By the way, looking at those Il-62 pics I can´t help but wonder how does that tiller work. What I mean by that is that I assume there is a way to "lock" the yoke while the pilot is busy with the tiller so the ailerons would not fiddle up and down again and again? Perhaps some kind of a switch, or a push-pull button? I don´t know, it looks a bit weird to see how two elements that control completely different things are mounted one on top of another.


Since we are with the Il-62, can you guys tell me what is that rather-old-video-cam looking piece under the captain´s hat?

Thanks a lot!
 
jetstar
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RE: Steering The Aircraft, How It's Done?

Tue Dec 16, 2008 10:51 pm



Quoting 2H4 (Reply 12):
Next time, just for a challenge, you should see if you can get from point A to point B using 90s for turns toward the good brake and 270s for turns toward the bad one.

To straighten out the nose wheel on an airplane like the Yankee, which has a free casting 360 degree nose wheel, you need the other brake to straighten out the nose wheel, all you will be doing is going around in circles on the good brake side.

Once the nose wheel is turned, it will stay that way until you use the opposite side brake.

JetStar
 
2H4
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RE: Steering The Aircraft, How It's Done?

Tue Dec 16, 2008 10:59 pm



Quoting Jetstar (Reply 14):
To straighten out the nose wheel on an airplane like the Yankee, which has a free casting 360 degree nose wheel, you need the other brake to straighten out the nose wheel, all you will be doing is going around in circles on the good brake side.

Once the nose wheel is turned, it will stay that way until you use the opposite side brake.

Ah, that makes sense. I think part of my brain was still stuck in Cessna mode.

2H4
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Jetlagged
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RE: Steering The Aircraft, How It's Done?

Wed Dec 17, 2008 12:41 am



Quoting Mastropiero (Reply 13):
By the way, looking at those Il-62 pics I can´t help but wonder how does that tiller work. What I mean by that is that I assume there is a way to "lock" the yoke while the pilot is busy with the tiller so the ailerons would not fiddle up and down again and again? Perhaps some kind of a switch, or a push-pull button? I don´t know, it looks a bit weird to see how two elements that control completely different things are mounted one on top of another.


Since we are with the Il-62, can you guys tell me what is that rather-old-video-cam looking piece under the captain´s hat?

Turning the steering wheel doesn't turn the control wheel, and vice versa, so the steering control is independent of the ailerons. Presumably they use some kind of concentric shaft arrangement.

The "rather-old-video-cam looking piece" is in fact the weather radar display, complete with hood to allow it to be viewed in bright sunlight.
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acNDTTech
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RE: Steering The Aircraft, How It's Done?

Wed Dec 17, 2008 5:19 am

A quick way to tell on most airplanes about if it uses a tiller or the pedals.....If the pilots are sitting above or in front of the nose wheel, they are probably using a tiller. If they sit aft if the nose wheel, they are probably using pedals. (This is also good info for those that have towed planes on the ground too, since most that have a tiller also need to have either scissors, a cannon plug, or something "undone" on the nose landing gear strut once a tow bar is attached, and vice versa).
 
DeltaGuy
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RE: Steering The Aircraft, How It's Done?

Wed Dec 17, 2008 2:44 pm



Quoting Jetstar (Reply 7):
If I remember back from my G2 days, like the JetStar there was no connection between the rudder pedals and the nose wheel steering

You bet, there isn't....IIRC, I think all the G1159's were like that, to include the GIII.

There are some pilots flying GIV's that will select rudder steering off from the pedals, and just use the tiller entirely during the takeoff roll, and rudders for directional control (once you're fast enough of course). Kind of frowned upon now, to me it doesn't make alot of sense but to those old GII pilots, it's what they know.

This was one of the contributing factors to that GIV accident up at Pawaukee, failure to maintain directional control by using this method.

DeltaGuy
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2H4
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RE: Steering The Aircraft, How It's Done?

Wed Dec 17, 2008 4:29 pm

So what's the smallest airplane that uses a tiller for nosewheel steering, and the largest one that doesn't?

2H4
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acNDTTech
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RE: Steering The Aircraft, How It's Done?

Wed Dec 17, 2008 10:31 pm

Maybe a Falcon 20, or Hawker 700????
 
jetstar
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RE: Steering The Aircraft, How It's Done?

Wed Dec 17, 2008 10:56 pm



Quoting 2H4 (Reply 19):
So what's the smallest airplane that uses a tiller for nosewheel steering, and the largest one that doesn't?

If I remember correctly, the Model 1121 Jet Commander had a wheel for nose wheel steering and I think it would be the smallest jet with a separate wheel for nose wheel steering.

The older LearJets’s used the rudder pedals for nose wheel steering, don’t know about the later ones and I am not sure about the Falcon 10. I think the Sabreliner 40 also steered through the rudder pedals

JetStar
 
acNDTTech
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RE: Steering The Aircraft, How It's Done?

Thu Dec 18, 2008 12:17 am

the Sabre 40's had tillers, I'm thinking about the old Jet Commanders and Falcon 10's....something tells me that they were both pedals. I'll know for sure in a few minutes.
 
acNDTTech
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RE: Steering The Aircraft, How It's Done?

Thu Dec 18, 2008 3:33 am

Falcon 10 DOES use a tiller for nose wheel steering......Still trying to find out about the Jet Commander. It probably does, since the Westwind does - I forgot about that, I used to tow a Westwind quite a bit back in the day when we had one based out of our hangar.
 
2H4
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RE: Steering The Aircraft, How It's Done?

Thu Dec 18, 2008 3:27 pm



Quoting AcNDTTech (Reply 23):
Still trying to find out about the Jet Commander.

Yep, it does. One tiller on the left side.

2H4
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bhill
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RE: Steering The Aircraft, How It's Done?

Fri Dec 19, 2008 3:07 am

Silly, silly members..stop bullshitting the Author. Nickbbu, if you have the security clearance to get on the tarmac, stoop way down and look closely at the "pavement" it's not solid, but made up of small conveyor belts. By changing the velocity of the various belts, the ground controllers can steer the aircraft as they desire...kinda like a tank tread, but upside down.. It is also how airplanes achieve rotational velocity. There are many, many posts and replies about this "conveyor belt technology".  Wink

Peace to All, and Happy Holidays.

Bhill
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acNDTTech
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RE: Steering The Aircraft, How It's Done?

Fri Dec 19, 2008 6:28 am



Quoting Bhill (Reply 25):
stoop way down and look closely at the "pavement" it's not solid, but made up of small conveyor belts. By changing the velocity of the various belts, the ground controllers can steer the aircraft as they desire...kinda like a tank tread, but upside down.. It is also how airplanes achieve rotational velocity

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