jet pack help needed(preferably from someone with a deegree in jet engines)

  1. #1

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    jet pack help needed(preferably from someone with a deegree in jet engines)

    Ok here it goes guys.Im working on a jet pack that will have the design of a standard Merr Sonn JT 12 jet pack but will be functional...so far ive determined a suitable fuel and a system for delivering fuel,my current design utilizes a valveless pulse jet engine design but i need more in put from people who have had some expirience with something like this,ive crunched the numbers and came out that a jet pack with my current design would give 10 15m high jumps with safe landing.Ive worke out a way to cotrol it wvia a programed chip and the first tests in computer simulations seem to prove the concept but the fact is the engine is a bit loud for my liking so imhoping for some helpfull suggestions.Thanks in advance for any suggestions and idea's you guys might give me.^^

  2. #2
    TD-4608's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    Could you clarify a bit more? In order to maintain control of a vertical 'rocket' for all intents and purposes, you need to be able to control several different axis'. This is extremely important if you are going to be jumping 45 feet in the air. You would need the ability to control yaw left and right as well as front to back. In addition, you would need the ability to reverse the thrust, or redirect the thrust in an opposing direction for safety reasons. Without the additional thrust mechanisms, you could use gyroscopes like a conventional rocket to control, but you would be limited by size. Honestly I respect the feat you are attempting, but I think this may be a little too ambitious. The record for a 'jump pack' as far as I can research is 7 meters, and you expect to more than double that. In addition, a jet engine as small as the one you are describing would not be able to generate enough thrust to lift a 180 lb. (I am assuming weight here). I can't remember the exact formula, but the thrust to weight ratio is also dependant on the diameter of the exhuast nozzle. A 2 - 4 inch exhaust nozzle like you are describing is insufficient.

  3. #3

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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    well to clarify i was gonna use a 5.2 inch nozzle,and use directional trust coupled with giros to mainatain stability of the thing but your right on the account of it being a bit underpowered that is why im switching to a special version of a valved pulse jet that triples the trust of my old model pulse jet,unfortunatly this also doubles my fuel consumption so i have to trow out the sleek design of the Merr Sonn JT 12 and go with a more rought design of the Mitrinomon Z-6 which i really dont like,and as for aditional trust mechanisms there really is no need for them because i calculated the trust needed to get the weight to that serten hight,im not atempting to build a hover pack but a jump pack which means controled time of trust and controled amount of trust to get the weight to a serten height,i might experiment with hover later on but for now im happy with just a jump with a controled desent...ive already tested my first prototype, and as for me being too ambitious xD i cant argue facts...ive always tried for more then anyone else
    Last edited by 72555; Jun 3, 2010 at 5:10 PM. Reason: forgot somethin

  4. #4

    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    I sense a funny but painful youtube video in the making

  5. #5

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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    berkal said: View Post
    I sense a funny but painful youtube video in the making
    XD lets hope just a funny one and not so painfull

  6. #6
    TD-4608's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    Well, an valve pulse jet engine small enough to fit on your back would generate roughly 5 to 10 lbs of thrust. If you weigh 150 lbs, the thrust to weight ratio is 0.06. You need a value of greater than '1' in order to lift your own weight, (winged aircraft do not need to at 1 or above because of the lift they get from their wings) and to accelerate you would need a much greater amount of thrust than that. A conventional Hydrogen Peroxide "jet pack" produces 280 - 300 lbs of thrust BUT it weighs 130 lbs or something like that. They also top out at roughly 7-9 meters in vertical height and can only hold enough fuel for 30 seconds of flight time.

    Secondly, a valved pulse jet engine is going to produce a heat load of roughly 1200 to 1500 degrees F. That's **** hot. I wouldnt even know where to begin with protecting yourself from that kind of heat. You may want to make your costume out of asbestos in order to keep the heat in check, (that's a joke).

  7. #7

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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    xD good one...

    but your wrong on your math there buddy a valved pulse jet engine with a combustion chamber in shape of a ball with a diameter of 5 inches and a nozzle of 2 inches would produce roughly 7000 kg/m2 of trust maybe 100 kg up or down so their compleatly feasable but your right on the thing producing alot of heat so your jokes kinda what i had in mind,a heat protection suit for the tests to see what area's need protection and which can do with out...also the trust is gonna be ingaged at 15 seconds a time by a chip with programed curves 5s climb at full power and 10s desent with a controled lowering of the amount thrust

  8. #8
    askywalker98's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    I don't know man, travisl sounds like they know their stuff...

  9. #9
    formerly Woodman woodman's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    isnt there a rule about the discussion of fully functional weapons and other dangerous props?

  10. #10

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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    lol...well so far its been working for me askywalker but only thing is i aint tested it with a user yet,just controled trust testing and stuff that doesnt require a person to wear it....


    as for the rule woodman i dont know of any but if there is one then the mods may by all means erase this thread

  11. #11
    askywalker98's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    Could you post some pictures and/or a video of what you have so far?

  12. #12

    Member Since
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    unfortunatly no i can....i made it a condition for my self not to take picture or video of the thing until its fully tested and functioning wwith a use...

  13. #13
    TD-4608's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    What did you need help with? Your original question was for help. It would help us help you if we could see your system.

  14. #14

    Member Since
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    i needed help figuring out alternative engines and fuels....im currently running a valved pulse jet andusing LPG...thats all the info needed forhelp with that...as for what it looks like find a pic of a bare meal Z-6 star wars jet pack with out the misile and that is it

  15. #15
    TD-4608's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)



    Dude- I don't get it. This is a valved pulse jet. It's 36" long and it can only produce 5 lbs. of thrust - MAX. This particular engine gets to be nearly 2,000 degrees. I just don't see how what your are doing is remotely possible unless you strap it to a chicken or something and even then you are going to just make some crispy BBQ that shoots around the sky like a deflating baloon. The thrust produced in your figures isn't possible in an engine that small. If you have developed something like that, then I would suggest you forget the costuming thing and get it patented quick. I'm sure every military in the world would be knocking down your door. Anyhow, this is above my skill level so ...

    May the physics be with you...

  16. #16
    askywalker98's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    72555 said: View Post
    unfortunatly no i can....i made it a condition for my self not to take picture or video of the thing until its fully tested and functioning wwith a use...
    I'm sorry but that's a silly excuse for not showing us what your working with.

  17. #17

    Member Since
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    nah actualy ya know what ive kinda grown tired of working on this thing its just too hecktic and like you said if i made it every military in the world would be after me..so im just gonna scrap it

  18. #18
    askywalker98's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    72555 said: View Post
    nah actualy ya know what ive kinda grown tired of working on this thing its just too hecktic and like you said if i made it every military in the world would be after me..so im just gonna scrap it
    Wow, this whole thread is hilarious. Thanks for the laughs bro.

  19. #19

    Member Since
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    you welcome dude...at least it served some perpuse xD

  20. #20
    rubio95's Avatar
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    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    The 'Similar Thread' function is awesome!!

  21. #21

    Re: jet pack help needed(preferably from someone with a deegree in jet engines)

    well, I would've loved to see it...

    Perhaps you could settle for something to give you a bit of a glide if you jumped off your roof or a trampoline. :P
    Last edited by Demagol; Jan 27, 2013 at 8:36 PM. Reason: Spelling

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