A lot of old fashioned science fiction features jetpacks, the design is very simplistic; two small jet engines attached to the back via straps. My company has been chosen to try and sell the jetpack in stores. The idea of the jetpack has obvious flaws in take off and landing, which would have to be fixed in order to make it feasible.
What changes would I have to make in order to make jetpacks feasible? With these changes made, how soon could my company hope to mass produce the jetpack?
Jet Packs have seen some serious development in recent years, so I am going to link you to the experts.
Here's an awesome vid link: Demo of the world's only lightweight jet pack.
It's amazing. We are sticking by the World's only JetPack title. When someone else develops a jet engined (not a gasoline powered ducted fan that weighs several hundred of kilos) backpack that the pilot can jog down the road with - then we will change the title. Our R&D plan includes longer endurance but trust me, when you fly at more than 100 mph for 10 minutes + you will know you're flying the world's only jetpack. One day we will be in a position to sell them and maybe sooner than people think but we want to make sure we have all the training systems etc right first. JB-9 is amazing but it's just the beginning.
This link contains specs and answers questions a lot better than I can! The future is now!
I know Mythbusters did an episode about building one off the internet some years back. If you can find that, you'll be able to see the problems they encountered and how to solve them. They also look at the Bell Rocket Belt.
There's also a lower tech version of it, the Bell Rocket Belt, but that's seriously underpowered for what you need.
As Erin Thursby noted, the technological limitations for a jetpack are already surpassed with our current technology. Therefore, the limitations of your jetpack entering mass-market aren't from a supplier end problem, but from a user end problem. Here are your major issues:
Likely though, these things could be addressed if your near-future environment has sufficiently advanced self-controlling vehicular technology - particularly for landing sequences. I would also recommend that you look into propeller hoverboards as a supplement or alternative to your jetpack. These aren't as constrained by fuel issues, can be readily recharged at work, and have large autonomy. On that note, what a time to be alive when someone tells you a jetpack isn't going to work because hoverboards are better. If you want to insist with the jetpack for performance reasons (higher altitude/speed) then look into incorporating some of the AI technology in the hoverboard, and develop a logistical way for people to refuel them.
The main issue with a jetpack is the amount of energy needed. No practical jetpack or rocket belt has ever been demonstrated which can carry more than a few minutes worth of fuel. Jet and rocket engines are notoriously inefficient in terms of fuel consumption, which simply adds to the problem. You will notice that modern jet aircraft have moved away from turbojets to turbofans, where the turbine turns a large fan to move a large mass of air somewhat slowly (while the internal jet engine moves a smaller mass of air very quickly). The larger the bypass ratio, the more efficient the engine.
Taking this to the logical extreme, we go to "unducted" turbofans, or turboprop engines, but you are probably not going to be too keen on having large fan blades or a propellor whirling just over your head...
The only practical way to overcome the limit is to have a beamed energy propulsion system, where a powerful laser of microwave generator on the ground provides the energy to a target on the backpack. While there have been serious proposals for this idea applied to helicopters, aircraft and even rockets, you can imagine the issues with that system scaled to a man portable backpack....
