Jump Pack Tech Calculation issues

[MadnessIndy]

My company is working on a few concept ideas for our field. Currently we are looking at jump packs concept work. We are looking to lift a human about 180 pounds, and about 50-60 pounds of gear = 230 Pounds Total. Our goal is to lift that weight about 20 Feet in the air while the subject is in a sprint. Any help would be much appreciated.

 

[Travis_King]

What about landing?

 

[MadnessIndy]

Landing would either consist of through a window and grappling the window. Or if fall like said 20 ft. A burst of power to slow the person down.
The System is more used to breach windows and add maneuverability to the "pilot"

 

[Barron]

Get a lower bound by treating it like a school physics problem:
Potential energy of person 20 feet in the air U = mgh
Potential energy stored in a spring = 0.5 k x^2. Maybe k = 10 inches or something convenient.
Spring rate for a car suspension spring might be k = 500 lbf/in, see if it can store enough energy.

For other mechanisms you can also check their energy content in the same way.

Use SI or you'll be screaming in pain working out the correct units for mass and force (they're can't both be pounds!).

 

[MadnessIndy]

Thank you very much. But I don't think we will be able to use spring systems. We are looking for a compression system IE (Air) if that's even possible. Our system will be mobile and will need to perform tests without stops. Springs would need to be retightened thus making it difficult to use. We need enough pressure and reserve to complete this motion about 10 times.
I will say that our target height was a little off the Actual height is 10 FT (3.04 M)

 

[etudiant]

Ten feet seems a much more plausible goal, especially as the center of mass for people is 2 feet above ground to begin with.
So you are trying to boost 240 pounds 8 feet, about equal to a half second drop at 1 G, so you need to kick up the person at 16 ft/sec.
My guess is that you could get this kind of kick from a small shell that drives an hydraulic piston.
That would give you the needed repeat jump capability and the hydraulics would help soften the takeoff and perhaps the landing.
Note that getting both legs to act together is critical, the user would probably be injured if just one leg fired.
Also, I'm not sure the usual human jumping reflexes would help a lot, as the launcher would be independent of muscle cues, so guiding the jumps might be a challenge.

 

[berkeman]

There is a much better and more practical way to do this, if I understand your requirements correctly.

You want a fit soldier or other officer to be able to launch themself and their pack to a height of 10 feet to breach a 2nd floor window, or something similar, correct? And you want the soldier to be able to do this several times in a row, it sounds like. Is that correct?

There is a non-powered, light-weight, portable way to do this, if I understand your requirements. We may want to take this to PMs if this is for law enforcement or military application...

 

[berkeman]

Thank you for your reply the project we are working isn't specifically designed for military. Would be nice to get there but for now we are more private and recreational. I would like to hear your ideas though.

Okay, if it's not for a current PD or military application, I'm okay with posting this in your thread.

If I understand your requirements correctly, then an obstacle course pole-vault type mechanism should work well. The main challenge is then to provide a solid pole plant point, either with the soldier pre-planting it, or with a fellow soldier planting it just before the first soldier uses it to launch up into the 2nd floor.

Pole vaulting is a simple and well-known way to convert running kinetic energy (KE) into a lift in height to gain gravitational potential energy (GPE). 10 feet is a modest height for a pole vault, and should be attainable by a fit soldier, even carrying a moderate size backpack. The pole can be carried through the breached window, to be re-used on another breach, and can be used to get back down to the ground smoothly.

The main challenge in this technique is to get a solid plant point for the pole in the initial lift. You may be able to use the side of the building for the plant point, but it may be better to have a tactically placed plant point a foot or two from the building. Would be fun to try this all out...

 

[MadnessIndy]

We at Madness Industries are sorry for the Vagueness of our post. Allow me ask this in a different way. We are concept and designers for the next wave in Paintball Tech. We are trying to enhance the game further than it is already. The system we wish to build would require the ability for a pilot to (in sprint, walk) trigger a reaction that allows the pilot to reach a second story window and add to the maneuverability. Using either a fuel or compression air system we need to achieve this goal. The best way to word it is we are building a burst Jetpack needed to sustain flight for 10 ft of lift.

 

[russ_watters]

Madness Industries? Sounds like you want us to design something for you to sell. How much are you going to pay us for that?

 

[MadnessIndy]

I can't find the formula and a power source capable of this feat. If this is possible then the "rig" will be used in madness events. We hope to set for sale but we are a small division of people. Currently we are just looking for thoughts. Soon we want to gain funding for production. At such a time we would hire for actual production.

 

[berkeman]

I can't find the formula and a power source capable of this feat. If this is possible then the "rig" will be used in madness events. We hope to set for sale but we are a small division of people. Currently we are just looking for thoughts. Soon we want to gain funding for production. At such a time we would hire for actual production.

Wanna?

 

[MadnessIndy]

Eventually yes. But we want to make sure its possible

 

[berkeman]

Eventually yes. But we want to make sure its possible

You miss my point. You are asking for professional ideas and help, and posting baby talk. Do you see a disconnect here?

 

[MadnessIndy]

Yeah. I am sorry, I am very busy and didn't think "wanna" would cause a problem. But we are getting away from the topic.