I, Professor Dubois, am once again at your service. I have done exactly what I mentioned the last time I spoke to you, which is to add a false cluster of four engines to the rear of our faux rocket. As you can see, I am fond of wine, and I have again used wine corks, this time to simulate the engines, one between each pair of fins.
Rocket with cluster of four faux engines
What is that, mes amis? My construction techniques leave something to be desired? But I remind you of what we discussed earlier, that we perform measurements and construct things to a degree of accuracy that serves our purposes, and any more is completely unnecessary, unless for aesthetic reasons. The engines, or corks, as you can see, are firmly attached with masking tape, and the string is secured at the new balance point, or center of gravity. This new center of gravity is only very slightly forward of where it was before we began adorning our model with cork, and is only a small distance ahead of the fins.
Swing the rocket around your head, if you please, and notice that it is now impossible to cause it to travel nose-first. In fact, it acquires many orientations as it travels. But why? Everything was going so well, it was looking so good, you say, and then the professor had to come along again and spoil everything. Not at all; we are learning, we are progressing. Soon you will have no doubts about the air worthiness of your craft; I am certain of it.
We must have engines, or at least one engine, and that one engine is likely to be somewhat heavy compared to the nose of the rocket. Things seem to go better when the nose is heavier, do they not? Well, then, let us add heavier and heavier weights to the nose until our rocket flies like a dart. But what if we add so much weight that the engine is no longer able to push our rocket up into the air? What to do? Perhaps adding weight is not the answer. But wait! Perhaps it is not the only answer; perhaps it is only part of the answer. Maybe a little weight is all right, but if it does not completely solve our problem, then what do we do? Use a smaller engine? Probably not.
Let us return to the function of the fins. Note that our fins are perpendicular to the rocket body, that is, they point straight out to the sides. You have, no doubt, seen fins that slope backward like the wings of a jet fighter plane. Now we are on the right track. Next time, mes amis, next time.
