How do space bound rockets go straight up, instead of flipping over, etc.?

Question

I remember watching videos of early US rocket experiments (probably in th late 40's and 50's) in which the rocket flipped over. How was that problem solved?

Answer 1

Rockets that flip over in flight have usually suffered a severe engine failure such as a cracked nozzle or thrust chamber.

During the ascent through the atmosphere, the center of drag is kept behind the center of mass.  This is how a weather vane works.  So any attempt to rotate (about the center of mass) out of a true heading is automatically corrected by aerodynamics.  As Goddard discovered the hard way, it doesn't matter whether the center of thrust is fore or aft of the center of mass.

As many others have mentioned, guidance systems in rockets sense improper rotation and correct it.  The correction is by thrust-vectoring: changing the direction of the rocket nozzle to counter the rotation.  Or it can be by steering jets that thrust in the pitch or yaw directions, like a canoeist at the back of the canoe paddling left or right instead of forward.

Find some video of the space shuttle just before ignition.  You can see the nozzles swiveling a bit in each direction as the thrust-vector actuators are tested.

All those guidance systems involve a fixed reference, usually a gyroscopically-stabilized platform mounted in gimbals that let the ship turn freely around it.  The angle formed by the ship and the stable platform helps it detect rotation.  The "error" between the desired orientation and the actual orientation can be fed as a signal to actuators (motors) that move portions of the rocket engine to change the angle of thrust.

Answer 2

sometimes they still do flip. it was solved by carefully balancing the propulsion to push up equally on all sides. like how you would lift a glass of water from the bottom without tipping it.

Answer 3

Rockets have fins, which are movable, and they can vary the amount of thrust to each engine, which can also help keep them pointed correctly. In the old films, either the computers guiding the rockets crashed (followed shortly by the rockets themselves), or some/all of the engines lost thrust, which would unbalance the rocket.

They were solved with better guidance systems and better engines.

Answer 4

the basic mathematics of rocketry were worked out a while ago, but basically they have to do with properly positioning the center of gravity and the center of pressure of the rocket.  look up those two concepts on google for a complete definition.  Basically you want the center of gravity forward  of the center of pressure (like a dart)  to do that you add weight to the nose, and/or surface area to the rear; hence the addition of fins at the bottom of the rocket and not the top.  

Answer 5

Todays rockets have very complex guidance systems with several servo systems, gyroscopes and of course, multiple computers - both onboard and land based, all working together to ensure that it goes along the planned trajectory. These systems control the power developed by each of the rocket engines to hold it on its course. The direction may look straight but it is the shortest and the best route to reach its destination.  

Answer 6

Guidance is one of the hardest problems to solve. Today it is onboard computers with complex programs that control the flight. In the old days it was clumsy mechanical or maybe simple electric devices attached to gyroscopes that attempted to do it.  

Answer 7

They have gyroscopes and accelerometers inside them that the rocket's guidance system uses to sense the orientation of the rocket and adjust the thrust of the engines to compensate. This is the one that was used on the Saturn V rockets on the Apollo lunar missions: http://en.wikipedia.org/wiki/ST-124-M3_i...

Answer 8

Guidance systems on the rockets adjust the flight paths a couple of ways:  First, on smaller rockets, there are fins at the bottom (or along the sides) that are turned to adjust the rocket's attitude.  

Second, on larger rockets (mostly all manned rockets) the engines are on gimbals, and the computer calculates the trajectory & rotates the engines to turn the rocket slightly one way or the other.  

The next time you see the shuttle launch, watch the video - the last few seconds prior to ignition, the computers "test" the engine gimbals by moving them a few different ways.  If the test works, the countdown continues until lift off.

Here's a You-tube video of them in action: http://www.youtube.com/watch?v=7ygCK0I1F...