[daveoflynn]

The primary things that's changed has been the availability of small powerful gas-turbine engines. That's what's made the folks you've mentioned, plus the Jetman project, possible.

To the best of my knowledge, this class of engines were originally developed for model aircraft.

[Zenst]

I had a quick look and seems some impressive little jet engines out there in the model aircraft domain. Quick look found one capable of 25KG thrust, weights just over 1KG. Then when you factor in fuel per minute and weight of fuel per minute. Can soon see why a 22 mile trip needed a refuel. Though still better than jetpacks.

But certainly not cheap, looking around $2,000 mark and much of that would be due to supply/demand aspect. If demand increased, that price would drop.

[cstross]

Dirt cheap by military supplier standards. Makes a lot of sense as a small drone/cruise missile engine.

Coming soon to a wannabe State Level Actor's arsenal! I'm thinking Da'esh here, but could equally well be white supremacist militias or the New IRA post-Brexit, or just about anyone with a weapons R&D budget in low single-digit millions.

Just as smartphones have given us all a general purpose James Bond gadget in our pocket, so too is the availability of cheap computing elements, drone components, and tech like this going to give every militia on the planet the sort of smart weapons capability that was bleeding edge in the 1990s.

[amelius]

Here's a nice video showing such a model jet engine slurping fuel.

https://www.youtube.com/watch?v=u42QrTqmYwg

The description of the video contains all the numbers, including:

    Max. power: 300N (30,5kg)

    Fuel consumption: 980ml/min (at max power)

    Price: 5295 €

[api]

So you're telling me we are finally going to get both shiny silver vertical landing rockets (SpaceX) and jetpacks!?!?!

[SpikeDad]

Big difference - shiny SpaceX rocket fails meh. Shiny jetpack fails dead person.

Some of the earlier attempts did have ballistic parachutes but you still had to deploy at least 75 feet high. Any lower and you're dead.