I’ve contemplated this many times. Is there some “little steering wheel” that pilots can access or do they use their main little joystick thing?
Depends on the aircraft: smaller planes do not have steering gear, they use a combination of brakes (there are individual breaks for each wheel) and rudder. Larger planes and jets have steerable gear.
There are several methods. In light aircraft, you generally use the rudder pedals. Either the nosewheel (or tailwheel) will be steerable, in which case pushing the left or right pedal will cause the aicraft to move to the left or right, or the nosewheel/tailwheel is free-castering like a shopping cart wheel, and you steer the aircraft by applying differential braking to the rear wheels with the toe brakes on the rudder pedal.
Larger aircraft may have a ‘tiller’ control separate from the flight controls, which steers the nosewheel through the hydraulic system. It’s often mounted on the left-hand firewall, so the pilot can control it with his left hand while operating the throttles with the right.
virtually ALL airplanes are steered by using the rudder peddals which also turns the nose wheel, as well as acting as brakes.
This isn’t really correct. There are plenty of very small aircraft with fully steerable nosewheells (the Cessna-150, for example). Other small aircraft use differential braking, such as the Grumman American light aircraft.
In heavier aircraft you can still find free castering or steerable wheels.
Virtually all large jets are steered using tillers. Some limited rudder control may be available through the pedals, and when landing the rudder is still effective at higher speeds to help maintain directional control.
Well, I had a huge reply all typed up, but on preview I see I’ve been beaten to it.
So I am just gonna shimmy on out of here.
Sam Stone Point taken, i was drawing on my (admittedly) limited experience with small craft, of which 90% consisted of tail-draggers. Those that were of the tricycle gear variety had the ‘trailing’ nosewheel which is not truly steerable but, as you mentioned, would follow similar to a shopping cart wheel. And, of course, rudder as needed.
You have, once again, succinctly cleared the waters where i have added to the turbidity.
Thanks,
What the heck, I’ll throw this into the mix:
For ultralights, which commonly do not have either castering wheels or differential braking (quite a few have no brakes at all) ground steeing is accomplished solely by means of the rudder. We are, though, talking about relatively lightweight objects here, with proportionaly large rudders.
Airliners have separate “tillers” for use on the ground while taxiing. These tillers steer the nosewheel using the airplane’s hydraulic system. The tiller takes varying designs, from a handle that pivots to an actual wheel (with a knob on top usually) that you spin. The deflection of the nosewheel you can get is truly amazing (usually around 85 deg, compared to [guessing] 45 deg for the front wheels of your car).
There is also a “lockout pin” on the nosegear that disconnects the steering mechanism. This allows the wheel(s) to free caster, and is used for pushback and towing of aircraft by tugs. The next time you’re flying, watch the airplanes around you getting pushed back. When the ground crew disconnects you might see someone standing near the front of the airplane holding up an orange or red streamer. What he’s actually holding up is the lockout pin, which has the streamer attached. He shows it to the captain as verification that the pin has in fact been removed and the aircraft can steer on it’s own.
Most airliners have the rudder pedals connected to the steering mechanism also. The deflection of the nosewheel is much less than with the tiller (say 25 deg or so), because using the rudder pedals to steer is usually done only on landing and maybe clearing the runway. Having the rudder pedals steer the nosegear makes the transition from flying to taxiing easier…as the rudder becomes less effective, the nosewheel becomes your primary lateral control.
Sinful, if you can’t imagine what the tiller everyone is referring to looks like, it is indeed a “little steering wheel” right where Sam Stone told you it is.
I used to fly a large jet where the rudder pedal-actuated nosewheel steering was best for small taxi corrections but more importantly for steering on the runway during takeoff when, for example, one might lose an outboard engine at a speed below one that the rudder has sufficient authority to keep the plane from being pushed off the runway by the opposite engine. Boeing designed it so that the authority you can have with just the pedals gives you the most directional control possible without skidding the nosewheel during takeoff. The tiller (as mentioned previously by others) is to get big turns at (slow) taxi speeds.
Every plane I’ve had the opportunity to fly in was a little different - I flew in a Cessna trainer many years ago and the nosewheel steering was controlled by the rudder pedals, but steering was only engaged when you pushed a red button on the control stick.
Hijack - the wheel brake controls are often on the rudder pedals too, but last summer I flew in an Aero-Commander (Volaire) Darter 100 (basically a discount C172) with nosewheel steering, but had a hand brake mounted on the instrument panel!
Boeing and McDonnell Douglas aircraft have never used hydraulics for nose gear steering. I have done nose gear steering rig on the 737, 757, and 777 and never dealt with the hydraulic system. All are cable controlled using a power assist drum to control the cables and a bicycle chain type mechanism between the tiller and the drum. And none require the installation of a rig pin to free spin. Rig pins are for exactly what the name means, rigging the steering system. The pin you see the mechanic holding after an airplane is pushed away from the terminal is a langing gear pin, it is installed while the airplane is on the ground to prevent accidental retraction of the landing gear.
Well, once again I should have qualified my remark with “some”, “many” or something similar.
Regarding the pins - the landing gear pin used to prevent accidental retraction is usually located up above the strut in the linkage somewhere.
The pin I was referring to is usually located near the tires themselves, in the steering mechanism. This pin has nothing whatsoever to do with gear retraction. In operations that I have flown, this pin is installed/removed every time the airplane blocks in and departs. The gear-retraction pin is only installed/removed on overnight stays and is removed before the crew arrives at the airplane. Thus in normal operation (and this operation includes Boeing and McDonnell Douglas aircraft) the pin removed after pushback is the “lockout pin”. A better description of this pin would be that it locks out any input from the cockpit controls. This prevents an inadvertant mashing of a rudder pedal from damaging the airplane or the tug. This may also be the “rig pin” you describe, but it wouldn’t be the first time the same item has different names to pilots and mechanics!
Maybe not on the 737, 757, and 777, but I’ve got one for you - I’m looking at my operator’s manual for a Boeing-made pre-707/720, 707/720-type airplane:
Regarding the second part of your question, the control stick – or in other planes the control yoke (which resembles a steering wheel in size and location, but also moves forward and aft) – only control pitch and roll, with no authority for steering on the ground. However, pilots DO use pitch and roll controls on the ground to keep the wind from upsetting the plane. Especially true for light tube-and-fabric taildraggers taxiing in crosswinds.
Because a yoke resembles a steering wheel, some non-pilots and students mistakenly try to steer the plane on the ground by rolling the yoke, as one would turn the wheel in his or her car.
Hope this helps!
If you ever get a chance, fly an Ercoupe. You steer it on the ground with the yoke, just like a car.
You’re wrong in what you say, in the case of Boeing 737, 757, and 767 at least. The nose wheel steering system is operated by hydraulics. It would be almost impossible to manoeuvre a large aircraft without the assistance of hydraulic power. Boeing aircraft use a system of cables moved by the tiller to operate a hydraulic steering jack which supplies the force to turn the nose wheels. It is this steering jack that has the lockout pin that pilot 141 referred to in his post. This pin when fitted allows the hydraulic pressure to have an idling circuit, which allows a tug to be able to move the nose wheels on pushback. With the pin fitted, the pilot has no control over the steering. Obviously it is essential that this pin is removed before the aircraft taxys away. As noted before, this pin is usually held up to the aircrew to indicate to them the aircraft steering is back in their control.
It is definately not the retraction pin which is held up to the pilot. Each landing gear does have a retraction pin which prevents inadvertant retraction of the L/G but this should have been removed long before the a/c is readied for flight. The only time I’ve seen this pin fitted when the a/c is in service is when there has been some indication that a L/G is not locked down correctly ( usually discovered by a red light in the cockpit).
V
Pictures for those inclined to look.
A DC-8 flight deck. The tiller is on the left side of the photo just above the top of the captain’s seat.
A Boeing 737. The tiller is the half-circle just to the left of the captain’s control yoke.
And finally a Boeing 777. Note the march of technology in this series of photos! The tiller is in the same place, but is of the “handgrip” type instead of a wheel. The 777 belongs to KLM and is one of the first aircraft equipped with the “Electronic Flight Bag”. This keeps all the Jeppesen charts used for flying in electronic format on the airplane. It allows for incredibly neat stuff like what you see here: a Jeppesen chart of the airport displayed next to the tiller, with the aircraft’s GPS position centered on the chart. Awesome!
It’s about time you guys caught up with general aviation.
Yeah, I hear you! 