KnowHow team explains: Things flying in the air must provide themselves a tremendous thrust or lift when they take off. For aeroplanes, birds, insects and so on, the lift is provided by the air travelling over the wings. Rockets don’t have wings, so all their lift must be provided by the thrust from their engines. And it’s obviously much more efficient to have the engines pointing straight down so that the rocket travels straight up, instead of wasting thrust by travelling horizontally along a runway.

However, planes and rockets share a common means of propulsion: both generate thrust by expelling hot gases from a nozzle. The jet or rocket engine pushes the gases backwards, which in turn push the plane or rocket forwards.

A plane is rather heavy, so it needs air streaming past it at very high speed to lift it up. It achieves this by travelling along a runway until it is moving fast enough to take off. A rocket, however, has to travel far from the earth where the air is very thin, if it is present at all, and consequently is not very good for lifting things.

So a rocket cannot use wings to get where it is going. Instead, it just has a very powerful engine expelling lots of gas, which does the lifting. Hence, a rocket does not need to speed along horizontally to get airborne, it just goes vertically up.