Steering

retina · 2018-05-17, 07:19

Why do most land vehicles control steering from the front, but most water, air and space vehicles control steering from the rear?

Nick · 2018-05-17, 08:12

The back wheels of a car play an important part in steering.
If you had a car which could balance without back wheels touching the road, turning the steering wheel might cause the car body to rotate instead of the front wheels.

Xyzzy · 2018-05-17, 14:23

The first cars were rear-wheel drive. Powering the rear wheels AND turning them was too complex at the time?

retina · 2018-05-17, 14:31

Quote:

Originally Posted by Xyzzy

Powering the rear wheels AND turning them was too complex at the time?

It might have been too complex at the time, but that doesn't explain contemporary front wheel drive vehicles; they still steer primarily with the front wheels.

science_man_88 · 2018-05-17, 14:54

My guess, air,water, and space vehicles need to control propellant ( usually partially the medium in which they move) whereas normal road vehicles don't.

Xyzzy · 2018-05-17, 17:02

The real answer, when it comes to anything regarding engineering, is cost.

Edit: Fun link: http://autoweek.com/article/car-life...ng-demystified

LaurV · 2018-05-18, 05:31

Some water toys control the direction from the front (and back, or front only). Some road toys control the direction from the back (and front, or back only). By water toys we mean 500 metric tons toys. And by road toys we think huge trailers with a thousand wheels, that usually carry heavy bridge pylons, electric transformers, long furnace contraptions, but also those autolifts which need a good control (alignment) of the front with the shelves or containers they operate. You can find youtube videos if you google for some "heavy trucks" or "extreme machines". Some air toys also use front controlled direction, usually those with a low speed.

The real answer when it comes to anything regarding engineering, beside money, is "control". Water offers a much higher resistance due to its viscosity, compared with air.
For boats (and also high speed airplanes) having a "stopper" in front and propulsion in back, will turn the toy upside-down (well, actually frontside-back, does English has a word for this?) uncontrollably when the plank is moved just a little bit. Remember Mr. Livingston? When he learned to fly supersonic, and a little turn of its head resulted in a tumble and a lot of feathers... To turn a ship 30 degrees you must turn its rear "fins" to any angle up to 90 degrees (perpendicular on the sailing direction) and wait until the ship turns. If the rudder would be in front, but the propulsion still on the rear, then turning the plank a few degrees will result in turning the ship uncontrollable. Try placing your mouse on the table, align a pen or pencil with it, then place a finger on the desk to block its front and push the pencil with another finger in such a way that the pencil pushes the mouse in the back. Both will rotate. Making both the propulsion and steering in front would result in some impossible angles for transmission, and impossible to support tensions in the ship's body due to water resistance/friction. You do not "drag" a thousand tons frying pan, you "push" it.

Same in driving, if you never drove a car with rear power (and front turning) on a slippery street, or black ice, and try turning and braking in the same time

then you don't know the difference between front and back powered (yeah, I know, this young generation all have ECP cars with automatic control of each wheel, ABS, blah blah, but no longer than 20 years ago, we used to drive cars that would appear strange for you now, hehe...)

pinhodecarlos · 2018-05-18, 06:56

To have space on the back for the boot....hehe

PS( I advise people to draw for all cases the free body diagram to understand why)

lavalamp · 2018-05-18, 15:12

From my experience of going the wrong way in racing games and reversing, it seems as though steering at the back is less stable. Possibly a result of the arcade-y style physics, or possibly a real effect, it seems a lot easier to make the car spin out that way.

Fork lift trucks do steer with the real wheels though.

For a plane, yaw control is usually done at the tail, and this directs air to one side or another. This seems like an undesirable thing to do at the front of the plane, as then you would redirect air into the plane itself, which surely would lose you some control authority and increase drag. Doing it at the back allows the air to be redirected without impinging on the aircraft. I suspect the reasoning is similar for watercraft.

Edit: For space vehicles, at least while in space, there is no "rear". While launching, engine nozzle gimbals give pitch and yaw control, but when in space attitude control is usually done with internal reaction wheels and reaction control thrusters.

lavalamp · 2018-05-19, 20:05

Somewhat related:
https://imgur.com/gallery/HhvRt9u

retina · 2018-06-11, 07:42

I appears as though this puzzle is harder than I thought it would be.

Still no correct answer.

2018-05-17, 07:19	#1
retina Undefined "The unspeakable one" Jun 2006 My evil lair 2²×1,549 Posts	Steering Why do most land vehicles control steering from the front, but most water, air and space vehicles control steering from the rear?

2018-05-18, 05:31	#7
LaurV Romulan Interpreter Jun 2011 Thailand 22613₈ Posts	Some water toys control the direction from the front (and back, or front only). Some road toys control the direction from the back (and front, or back only). By water toys we mean 500 metric tons toys. And by road toys we think huge trailers with a thousand wheels, that usually carry heavy bridge pylons, electric transformers, long furnace contraptions, but also those autolifts which need a good control (alignment) of the front with the shelves or containers they operate. You can find youtube videos if you google for some "heavy trucks" or "extreme machines". Some air toys also use front controlled direction, usually those with a low speed. The real answer when it comes to anything regarding engineering, beside money, is "control". Water offers a much higher resistance due to its viscosity, compared with air. For boats (and also high speed airplanes) having a "stopper" in front and propulsion in back, will turn the toy upside-down (well, actually frontside-back, does English has a word for this?) uncontrollably when the plank is moved just a little bit. Remember Mr. Livingston? When he learned to fly supersonic, and a little turn of its head resulted in a tumble and a lot of feathers... To turn a ship 30 degrees you must turn its rear "fins" to any angle up to 90 degrees (perpendicular on the sailing direction) and wait until the ship turns. If the rudder would be in front, but the propulsion still on the rear, then turning the plank a few degrees will result in turning the ship uncontrollable. Try placing your mouse on the table, align a pen or pencil with it, then place a finger on the desk to block its front and push the pencil with another finger in such a way that the pencil pushes the mouse in the back. Both will rotate. Making both the propulsion and steering in front would result in some impossible angles for transmission, and impossible to support tensions in the ship's body due to water resistance/friction. You do not "drag" a thousand tons frying pan, you "push" it. Same in driving, if you never drove a car with rear power (and front turning) on a slippery street, or black ice, and try turning and braking in the same time then you don't know the difference between front and back powered (yeah, I know, this young generation all have ECP cars with automatic control of each wheel, ABS, blah blah, but no longer than 20 years ago, we used to drive cars that would appear strange for you now, hehe...) Last fiddled with by LaurV on 2018-05-18 at 05:34

2018-05-18, 06:56	#8
pinhodecarlos "Carlos Pinho" Oct 2011 Milton Keynes, UK 3·17·97 Posts	To have space on the back for the boot....hehe PS( I advise people to draw for all cases the free body diagram to understand why) Last fiddled with by pinhodecarlos on 2018-05-18 at 06:58

2018-05-18, 15:12	#9
lavalamp Oct 2007 Manchester, UK 5·271 Posts	From my experience of going the wrong way in racing games and reversing, it seems as though steering at the back is less stable. Possibly a result of the arcade-y style physics, or possibly a real effect, it seems a lot easier to make the car spin out that way. Fork lift trucks do steer with the real wheels though. For a plane, yaw control is usually done at the tail, and this directs air to one side or another. This seems like an undesirable thing to do at the front of the plane, as then you would redirect air into the plane itself, which surely would lose you some control authority and increase drag. Doing it at the back allows the air to be redirected without impinging on the aircraft. I suspect the reasoning is similar for watercraft. Edit: For space vehicles, at least while in space, there is no "rear". While launching, engine nozzle gimbals give pitch and yaw control, but when in space attitude control is usually done with internal reaction wheels and reaction control thrusters. Last fiddled with by lavalamp on 2018-05-18 at 15:14

2018-05-17, 08:12	#2
Nick Dec 2012 The Netherlands 1702₁₀ Posts	The back wheels of a car play an important part in steering. If you had a car which could balance without back wheels touching the road, turning the steering wheel might cause the car body to rotate instead of the front wheels.

2018-05-17, 14:23	#3
Xyzzy "Mike" Aug 2002 2⁵·257 Posts	The first cars were rear-wheel drive. Powering the rear wheels AND turning them was too complex at the time?

2018-05-17, 14:54	#5
science_man_88 "Forget I exist" Jul 2009 Dumbassville 2⁶·131 Posts	My guess, air,water, and space vehicles need to control propellant ( usually partially the medium in which they move) whereas normal road vehicles don't.

2018-05-17, 17:02	#6
Xyzzy "Mike" Aug 2002 2⁵·257 Posts	The real answer, when it comes to anything regarding engineering, is cost. Edit: Fun link: http://autoweek.com/article/car-life...ng-demystified

2018-05-19, 20:05	#10
lavalamp Oct 2007 Manchester, UK 1355₁₀ Posts	Somewhat related: https://imgur.com/gallery/HhvRt9u

2018-06-11, 07:42	#11
retina Undefined "The unspeakable one" Jun 2006 My evil lair 2²·1,549 Posts	I appears as though this puzzle is harder than I thought it would be. Still no correct answer.