<blockquote><font class="small">In reply to:</font><hr /><p>But is there such a thing as too much gimbaling?<p><hr /></p></p></blockquote><br /><br />The smart-alec answer: yes; that's called overcorrecting. <img src="/images/icons/wink.gif" /> Seriously, the guidance computers are extremely important in any rocket because of this. If they gimbal farther than is called for in the situation, they'll make things worse. One of the worst things that could happen is where the rocket is, say, .005 degrees off, so the computer overcorrects, putting it .006 degrees off in the other direction, whereupon it gimbals the other way to go to .007 degrees, and pretty soon the RSO is pushing the self-destruct button.<br /><br />Most rockets steer via vectored thrust. That is, to change the direction of travel, they change the direction of thrust. Some move the entire engine. Most move just the nozzle. Some very early rockets (the V-1 and the Redstone, for instance) had vanes in the rocket exhaust which redirected it as desired. Some very small rockets (such as air-to-air missiles) are able to steer using control surfaces, but that's completely out of the question for an expendable launch vehicle; the forces involved are just too severe.<br /><br />One of the more novel methods of steering was employed on the gargantuan N-1 rocket, the USSR's answer to the Saturn V. The N-1 was an official state secret until perestroika, disavowed in large part to avoid the embarrassment of admitting that the Americans were beating them. (Although there were some brilliant and immensely dedicated scientists involved in the Russian space program in those days, as far as the Kremlin was concerned, the space program's main usefulness was in propaganda. Therefore, failures were hidden, objectives redefined, and focus placed on whatever actually succeeded. Nothing else mattered to the politicians. Unfortunately, this inevitably crippled the program. It could have been much more successful had the politicians <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>