"Jet" pack

Mike Everman
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"Jet" pack

Post by Mike Everman » Mon Dec 20, 2010 11:53 pm

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metiz
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Re: "Jet" pack

Post by metiz » Tue Dec 21, 2010 12:19 am

Although incredibly cool, I just dont understand why it is apparently so difficult to make an actual JETpack. If some-one slips me 50.000$ I'd be happy to whip one up for them :P
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Re: "Jet" pack

Post by ganuganu » Sun Mar 27, 2011 1:20 pm

Thats really awesome..lets make a jetpack using pulsejet metiz.. :D :lol:

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Re: "Jet" pack

Post by metiz » Sun Mar 27, 2011 1:52 pm

Pulse-jets are not well suited for a vtol "jetpack" device. You'd need a huge engine to get airborn and the noise comming from that engine strapped to your back will be intollerable. you're also one flameout away from a swift dead.

But while we're on the subject, if anyone cares to donate 100k, I'd be happy to make one from turbine engines :D
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Re: "Jet" pack

Post by Johansson » Tue Mar 29, 2011 8:16 pm

I agree with Metiz, it is difficult to understand why the guys with more money than hairs in their asses haven´t built a working jetpack already. I mean, a couple of 40lbs RC engines powering a free turbine driven ducted fan and two controllable nozzles for steering and thrust control.

I mean, what´s the problem? :mrgreen:

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Re: "Jet" pack

Post by Viv » Wed Mar 30, 2011 11:58 am

I think they have done an impressive amount of work to produce what is arguably a very compact power source (2 stroke V4) and an airframe to take it, what leaps out at me though is all the jetpacks suffer from control instability issues and the only thing to stabilize them is the pilot (and his reactions) what we really need next is the fly-by-wire control loop technology from aircraft that's been developed to be shrunk to fit jetpack applications. The jetpack pilot learning curve looks potentially painful otherwise ;-)

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metiz
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Re: "Jet" pack

Post by metiz » Wed Mar 30, 2011 1:25 pm

If you build your jetpack in such a way that the pilot is the centre of gravity then I see no real stability issues that can't be easily overcome.

So how about that money :mrgreen:
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Re: "Jet" pack

Post by PyroJoe » Wed Mar 30, 2011 1:45 pm

Replacement landing gear can be expensive at times. :D

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Re: "Jet" pack

Post by Viv » Wed Mar 30, 2011 2:41 pm

metiz wrote:If you build your jetpack in such a way that the pilot is the centre of gravity then I see no real stability issues that can't be easily overcome.

So how about that money :mrgreen:
Hi Metiz

I don't see the pilots center of gravity as the only stabilizing influence needed when it comes to flying safely, you can see the wobbly flight is down to the pilots skills and experience (newbie pilots must be worse) a fly-by-wire system with a flight control software package (aka modern fighters and airliners) would clean up the flight stability and improve safety by off loading the basic flight controls from the pilot.

Modern fighter design makes unstable airframes stabilized by computer flight control systems, this is considered an advance and a benefit, jetpacks are inherently unstable air frames by any ones consideration yet we think a pilot can manually tame it and fly it safely? that does not make sense to me ;-)

That's why I think a flight control system is the next step not the basic air frame or power source

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Re: "Jet" pack

Post by metiz » Wed Mar 30, 2011 3:23 pm

Hey Viv

Looks like a clear case of Ockhams razor to me :)

The Wright brothers didn't need stabilizing systems to keep their plane airborne, and neither should a "beginners" jetpack.

the airframe instabillity you talk about in modern fighters is there to make the plane as manoeuvrable as possible and a fly by wire system is needed to prevent them from falling from the sky.

A jetpack, however you look at it, isn't nearly as complex as a fighter. You just want a functional jetpack. Once that's done, you can think about deliberately destabilising it :P

Asume the person flying is the centre of gravity. It's like hanging on ropes attached to your shoulder. If it's still unstable, why not try a bunch of gyro's to limit pitch and yaw of the pilot, That's a lot less complex than a fly by wire system
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Re: "Jet" pack

Post by Viv » Wed Mar 30, 2011 4:01 pm

Hi Metiz

Yes I know that and I know why too ;-)

Why is adding some Gyros not a flight control system the same as I mentioned? fly-by-wire is pretty generic for flight control systems now as its implicit to the application, ie its not simply the replacement of physical links to control surfaces by electrical signals but that implementation of a flight control software package.

The wright brothers went with what they had and what they could think off, a hundred years later I do not feel the same limitations as they faced should limit a design today, do they sell cars with out antilock brakes today because Benz did not have them? because with a bit of training you can get used to not having them?

I think the basic stability of a jetpack and hence its usability is severely restricted by its lack of an active flight control system to smooth out pilot input and errors, lets face it if the gravity stabilized jetpack is hovering the pilot messes up his throttle setting he slams in to the ground or rockets off in to the sky, the more limits and additions of bits and peaces to the flight control you add to get around this the closer you end being to fitting a proper flight control package.

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metiz
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Re: "Jet" pack

Post by metiz » Wed Mar 30, 2011 6:11 pm

Ah shit, typed a full comment and then forgot to click send...

Anyway, flight controll systems are a good idea, but try to make a functional jetpack before you try to design one that can hit mach 1 on the first attempt. Jetfighters with an unstable flight frame are an advancement, not something the Wright brothers thought about when they made their first plane. Old fighters without that system work to. Not as well, but they work.

What I'm trying to say is: build one that works before you start adding more advanced systems

(the first one was much better :cry: )
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Re: "Jet" pack

Post by Jutte » Sun Apr 03, 2011 11:16 am

Ha...Love this topic.
Well it depends how much money you can throw at your jet pack...
and if you want you Mother to be able to fly it...LOL!
Sort of - "I can't afford to make an two wheeled segway and it's associated electronics etc - so I 'll just make a tricycle".
The Martin Jet Pack has gone the way of a flight control system - and as a result every day
ordinary folks can actually fly the thing without making craters in walls ,ceilings and the ground etc.
There's some pretty good vids on some of the Bell Jet Belt/Pack derivatives pilots losing it while training-
sort of gives you an idea of what happens when 'you know what hit's the fan'.
Augumented flight controls are what the future holds...unfortunately I am sort of stuck in the
"just make a tricycle" zone... :lol:

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Re: "Jet" pack

Post by Viv » Mon Apr 04, 2011 7:10 pm

Ha! too funny Metiz we have all written a post and then forgot the press send ;-)

Its six of one and half a dozen of the other basically, if you build a pack capable of getting off the ground you are then most likely yo pile it back in to the ground at high speed, so do you design the flight controls first or second? before flying is the smart answer ;-)

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metiz
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Re: "Jet" pack

Post by metiz » Mon Apr 04, 2011 10:14 pm

Viv wrote: Its six of one and half a dozen of the other basically, if you build a pack capable of getting off the ground you are then most likely yo pile it back in to the ground at high speed, so do you design the flight controls first or second? before flying is the smart answer ;-)
Sounds like something a pussy would say :P

I was thinking though: how about a scale model? like 1/8th true size. Make it remote controllable and see how that works. If you can source one of those small rc engines then you're in business, without breaking the bank (to much)
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