WHAT IS A JETPACK?

What Is A Jetpack?

There is some confusion over what a jetpack is/ was/should be.

Basically it comes down to a disconnect between what is science, what is engineering and what is ‘common usage’.

1. Science

Science says that a Jet is a ‘coherent stream of particles moving in a parallel direction’.

This is why we talk about the ‘jet stream’ in the upper atmosphere. This is why a jet ski is called a jet ski. This is why a jet boat is called a jet boat. This is why the Coast Guard call their water jet powered craft ‘jet propelled’.

This is why our device is a jetpack. There is a coherent stream, all the engineering calculations, control calculations etc. are based on the fact that there is a jet of air exiting the fanjets.

2. Engineering

Many engineers, particularly in the aviation industry, make distinctions.

A gas turbine powered’ prop is not a jet but uses gas turbine calculations.

Whereas a gas turbine powered fan (turbo fan) they call a ‘jet’ in actuality it could more correctly be called a ‘gas turbine powered ducted fan’.

3. Common Usage

To most people a device that you strap on your back which burns fuel, makes noise and you fly around in, is a ‘jetpack’. The majority of people call the Bell Rocket Belt a ‘jetpack’.

Actually it is not what an engineer would call a jet, it is a rocket. However, by the science definition, the coherent stream of steam coming out of the nozzles is a ‘jet of steam’.

So why call our device a ‘Jetpack’?

Well, by both common usage and science it is a jet. We already have jet ski and jet boat. I do not believe that an aviation engineer will be able to convince all those owners to start calling their devices a ‘water pump propelled boats’.

In the end we found that 95% plus of people call it a jetpack when they see it, so why fight that ?

If you have a very narrow view of what a ‘true jetpack’ is (i.e. that it is a pure jet) then none have ever been built. The closest would have been the Bell jet belt, but again this was not a ‘true jet’, it was bypass ratio gas turbine powered. In fact I cannot think of any ‘true jets’ in the GA industry, most are Fanjets.

Perhaps now you see that the ‘correct answer’ is far more complicated and debatable, so much so that normally it is not worth even starting the discussion, because the ‘correct’ answer relates to opinion not fact.

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