Rocket Jumping

Ok, this is a post to debunk all my bunkmates who refuse the believe that a certain concept is im-possible in real life. Rocket jump is a nifty trick built into the game engines of the game that we are playing, Team Fortress 2. Basically, you point your rocket launcher to the floor, jump and fire at the same time. You take a bit of damage from the blast, but you literally sky rocket forward allowing to 'jump' further than is necessary.

Now the challenge is: whether rocket jumping is possible in real life. After all, its a fine and dandy concept in the game, but can it be done in real life? My answer is yes. First of all, my disbelieving bunkmates who think I have gone utterly crazy say that in the game, the explosion from the rocket propels you forward. Their argument advances then to say that in real life, the explosion would have killed you. Blast you into little bits. Now, my friends, a rocket designed for war is designed as such: a booster at the back which propels the rocket forward when fired and a warhead which explodes on hitting the target. The propulsion for a rocket is in the gases leaving from the rocket. Since we are talking about using the rocket launcher here, we will be utilising the recoil of the launching tube to propel ourselves.

Now this is where my friends advances the next bit of their argument. Gases from the rocket are expelled from the back of the open tube. This is due the ingenuity of mankind for they invented the recoiless rifle. The recoiless rifle basically allows for the firing of heavier projectiles than we otherwise be impossible due the large recoil. The recoiless rifle functions pretty much like any other rifle, except that it has a hole at the back. When fired however, instead of propellant blast following the projectile out by the front muzzle, a large portion is allowed to escape, providing an inertial force to counter the inertia of the projectile. Despite the name, in real world, the forces seldom cancel perfectly, leading a noticeable recoil of the gun. Additionally, old and poorly maintained weapons have faulty gas ports, leading to a failure of the recoil-dampening effect.

Ok, so we have the possibility of utilising the recoil tied down. Next is to run a calculation of its feasibility. We will be utilising the most basic of basic physics equations that every JC student should know: Conservation of momentum. And the rocket launcher in question? A M1 bazooka.

The laucher weight is roughly 6 kg. The missile weight is 1.59kg. The maximum range is 365m. Next, we need to calculate the speed that the rocket is fired since this data is not provided. Estimating that the rocket is launched horizontally, the range is basically determined by how long it takes for the shell to fall to ground. Since it is fired from shoulder, we estimate the shell vertical distance that it takes to fall is roughly 160cm. Analysing the horizontal and vertical components separately, time is takes for shell to fall to ground is given by t=sqrt((2*1.6 m)/9.81). Range of missile is therefore r = v * sqrt(9.81/(2*1.6m)). Since we know r to be 365 m, and need to find v, its a matter of reaching for the calculator, and out pops the answer that the missile travels at approximately 639 m/s.

Now, applying conservation of momentum, the forward blast of the missile must be compensated by a backward recoil of the rocket launcher. Therefore,
1/2 (missle mass)*(missile speed)^2 = 1/2 (launcher + human mass) * (recoil speed)^2

Substituting and crunching through the numbers, the speed of recoil should be able to launch a person like me, at the speed of roughly 100 m/s, which is much much greater than my SBJ speed during IPPT(Roughly 22m/s for me).

Now, rocket lauchers do not blast backwards at this speed because they are specifically designed to dampen the back blast, eg. using a hole and gas ports to allow gases to escape to rear, portion of shell detaches and propels to the back, carrying most of the backward momentum away. Remove this modifications, and voila, see the recoil propel you!

Of course there is still the problem of the the explosion of the warhead to deal with. One, we could possibly jump off a cliff and fire, so that the explosion of the blast is not so near to us. Or we could wear a heavier armour and use a bigger missile. Certainly both methods are liable to suffer burns and broken bones, since we humans do not have bodies suited for jumping at such great speeds.

This whole thing has been to prove that as a concept in the real world, using a rocket launcher to jump is perfectly possible. Obviously no one survives this unscathed, which is why the game TF2 made it such that all the soldiers that rocket jump will suffer 2 injuries: from the blast at such close range, and from landing due to high velocities. Is smashing your head against the wall not possible in real life? Yes it is, but you would most likely suffer great damage, or even die from this action, but that does not prevent this action from becoming an unreal situation that is only worth talking about in games and books. Whoever has the guts to do this obviously can prove that this is possible.

Now, for my dear readers who do not know what this game is and therefore does not even know what I have been talking about in the past 10 min, here's a video from the game that illustrates this famed trademark move.

And the character in question: Meet the Soldier.