Once you've understood the basic principle behind rocket-jumping, and understand how explosives work, you may find you can work out ways to refine your technique. One good source of general and practical information is The Rocket-Jumper's Guide To Quake. Here I'll take a closer look at how we can use the physics of Quake to get the effects we want.
OK, the first thing to remember is that if you start going up twice as fast, you won't just end up going twice as high. In fact, if my high-school kinematics hasn't deserted me, the height you reach increases with the square of the initial upwards velocity. So a little more pain at the start can mean your jump takes you appreciably higher. Also, combining the boost with some other upwards velocity reaps valuable rewards. So you'd better jump, for a start! Also using the effects of two explosions at or around the same time and place (as in grenade+rocket-jumping) or the lift that a slope can give you will pay off handsomely.
The second thing is that the closer you are to the explosion, the more damage it will do, and hence the bigger the boost you will receive. Experienced rocket-jumpers know that they can make different strength rocket-jumps by carefully timing the moment they release the rocket relative to when they leap into the air. In some cases, you may want to get the maximum possible height for your jump. This is most important for speed-runners who need those extra few pixels of height in order to accomplish a trick short-cut jump.
It doesn't matter how good your timing is if your computer can't be as
precise as you need to be. Because of this, the most effective of
rocket-jumps can often only be done on a machine with a good
frame-rate, so that you can time things so that the explosion happens
as soon after the jump as is possible. For a vertical jump, if you can
take as much as 53 damage, you are probably making the highest
possible leap. If you are on a slower machine, we've found that using
tactics such as reducing the size of your screen, and even setting
R_DRAWFLAT 1 to minimize the work Quake has to do can
spell the difference between landing on the ledge, and falling to your