Rocket from Balloon

Discussion in 'The Watering Hole' started by aerostadt, Nov 26, 2019.

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  1. Nov 30, 2019 #31

    jsdemar

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    Size the balloon for the equivalent lift capacity of a B52 or modern equivalent. The cost is high either way. Air launch has the advantage of being piloted to a specific launch lat/long and a mission abort is recovered intact by landing on a runway.
     
  2. Nov 30, 2019 #32

    Wallace

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    So, it ain't gonna happen...
     
  3. Nov 30, 2019 #33

    Wallace

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    I'll take 2.
     
  4. Dec 3, 2019 #34

    rokit

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    Pegasus launches start horizontally from 40K ft. The launch vehicle takes care of achieving the proper trajectory after release from a carrier aircraft:

    https://en.wikipedia.org/wiki/Pegasus_(rocket)

    Mike
     
  5. Dec 3, 2019 #35

    Wallace

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    That's pretty cool. But...Wiki ruined it by asking for money I don't have:(
     
  6. Dec 3, 2019 #36

    BABAR

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    Great article, thanks!

    Describes some interesting advantages of Aircraft Launched satellite rockets compared to both ground and balloon launched.

    You can launch the thing from pretty much any latitude or longitude you want, so your satellite starts its initial launch at the right trajectory for it's final planned orbit. Can't do that with a fixed land-based launch site, and not easily achievable with a balloon either.

    Also interesting that even at 40K feet, allows some modifications of the lowest stage nozzle that make it more efficient compared to a ground launch.

    One thing article mentioned (that hasn't been done yet) is launching three rockets at once from a single aircraft. Get a lot more bang (well, hopefully not a real bang, but you know what I mean) for your buck that way.

    I'm a little bit surprised that they fire this thing horizontal, I would think the aircraft could pitch nose up a good bit (maybe 45 degrees) for a brief moment to provide more vertical inertia to the rocket. I'm trying to remember if the F15 launched AntiSatellite missile did that. 'Course, going vertical in an F15 is no big deal compared with a BUFF or the Lockheed TriStar, but I suspect both of the latter big birds could hack it at full thrust for a minute or so before stalling.
     
  7. Dec 3, 2019 #37

    Wallace

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    I'm intrigued also. There's gotta be a simple reason for the horizontal launch, just can't figure it out.
     
  8. Dec 3, 2019 #38

    rokit

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    Getting the rocket safely away from the aircraft in case something goes sideways when it ignites.

    Mike
     
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  9. Dec 3, 2019 #39

    DAllen

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    One question I have about the rocktoon concept...Don't rockets need to be launched from precise locations and trajectories to get to specific altitudes for orbit? Wouldn't that be pretty hard to do with something that is going to easily be shifted by the wind? I donno, maybe this isn't as bad as I think it is. Seems like you'd have to burn up a lot of fuel making course corrections.
     
  10. Dec 3, 2019 #40

    kuririn

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    The Regulus system linked in the first post has maneuvering thrusters, plus it can be mobile launched and set up with the trailer system. So I guess it can go anywhere there are roads (with permission, of course). Sounds like it will still cost a pretty penny though.
     
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  11. Dec 4, 2019 #41

    Wallace

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    Sort of get it...But, why would it be different if the launch vehicle were pointed up 40 or so degrees? At speed I doubt gravity'd be much of an issue?
     
  12. Dec 4, 2019 #42

    SDramstad

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    You stall an aircraft carrying a load like that and you will crash the aircraft.
     
  13. Dec 4, 2019 #43

    djs

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    "I got an idea! Instead of this complex thingie plus a balloon, why don't we just use a booster rocket stage!?"

    ~some Leo Aerospace guy a year from now...
     
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  14. Dec 4, 2019 #44

    Wallace

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    Brilliant!
     
  15. Dec 4, 2019 #45

    Peartree

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    It may be in how you are visualizing the launch. It is NOT like a heat seeker leaving the rails on an F-16. Although carried underneath, it launches like the original x-planes launched. It doesn't "launch" so much as it is simply "dropped" and then ignited. That way the rocket is safely away from the aircraft before the motor ignites. Being done that way, having the plane pitch up before dropping the rocket doesn't add anything and only complicates the needed flight pattern. Once the rocket ignites, changing course under thrust to point up is easy-peasy.
     
  16. Dec 4, 2019 #46

    djs

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    Thinking about this- if the Leo Aerospace system includes a rail to launch the rocket from, how do they keep the rocket from not torching the balloon?
     
  17. Dec 4, 2019 #47

    Wallace

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    Good explanation. Thank you.
     
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  18. Dec 4, 2019 #48

    Wallace

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    Single use?
     
  19. Dec 4, 2019 #49

    djs

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    Hopefully not, as in this case you could have burning sh*t falling from the sky....
     
  20. Dec 4, 2019 #50

    kuririn

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    The article says reusable up to 100 times. That's the plan, anyway. One expensive aerostat (or is it aerostadt)?:D
     
  21. Dec 4, 2019 #51

    Wallace

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    that's where the handiest ever tag line comes into play, "It's ok, it's not mine."
     
  22. Dec 4, 2019 #52

    Nytrunner

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    Woo! More things to terrorize the Amish with!

    upload_2019-12-4_12-52-39.png
     
  23. Dec 4, 2019 #53

    BABAR

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    I agree with it being a more complicated, also agree with SDramstad, that you don't want to stall the aircraft.

    I WAS however thinking that releasing in an upward trajectory provides two benefits.

    First, you take advantage of the initial momentum of the rocket, converting it from a purely horizontal vector to a partially vertical one. I'm suspecting that airplane gas is relatively cheap compared to having to build a bigger rocket to hold more propellant. I was thinking firewall the throttles and go to max air safe speed then go to max safe upward pitch, releasing the rocket well before stall speed. Still should have plenty of time to clear the rocket before engine ignition. I have been amazed at how steep many commercial passenger jets climb after take off. It just seems a shame to waste potential vertical momentum if you don't have to. Part of the reason for launching from an aircraft in the first place is to get max efficiency by launching above much of the high drag atmosphere. Every little bit helps. As you said, "changing course under thrust to point up is easy-peasy". It is not however "free", there is an energy cost involved.

    Second, using that momentum, you may get a certain amount of vertical altitude coasting before you have to ignite your motor. The higher you get before you ignite your motor, the less dense that atmosphere which is an advantage both in terms of drag and apparently in optimal "nozzle configuration."

    On the downside, aircraft may not be able to handle the strain or may stall (both obviously very bad!)
    I'm not sure how much propellant you would save, both from converting some of the momentum from horizontal to vertical and from delaying ignition of the motors at a higher altitude. Also not sure how much propellant is spent "re-orienting" the missile from horizontal to vertical (or relatively vertical, eventually the satellite will have to be in a horizontal trajectory for orbit.) My AstroPhysics course was in the early 80s, and I don't remember much, except that energy expenditures for orbital changes are NOT intuitive!
    Also if you DO ignite motor higher, your initial rocket fin effectiveness (if you go that route) is less, but in all cases fin effectiveness is eventually zip once you are above most of the atmosphere, so eventually you are using thrusters for changes in attitude anyway.

    "Ground launched" versus "aircraft launched" versus "balloon launched"....., major factor is who can find the cheapest AND most reliable technique.
     
  24. Dec 4, 2019 #54

    boatgeek

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    Fire blankets. Really biiiig fire blankets. :D
     
  25. Dec 5, 2019 #55

    Wallace

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    Just a thought, but. How 'bout we :A, turn this into a fun/spoofy type of topic? Or:2 Speak of it as though we are veterans of multiple balloon launches and obviously know everything there is to know. Or; C: Carry on as tough this post never existed?
     
    Last edited: Dec 5, 2019
  26. Dec 5, 2019 #56

    boatgeek

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    I vote (a) for all rockoon threads, but that was probably already clear. :) I would welcome any rockoon thread that had serious technical info about how one would actually accomplish this, though.
     
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  27. Dec 5, 2019 #57

    dhbarr

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    Three balloons, inverted tetragon.
     
  28. Dec 5, 2019 #58

    Wallace

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    Can you draw us a pic? Sounds like fun..
     
  29. Dec 5, 2019 #59

    Wallace

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    I was thinking of the guy that filled hundreds of kids balloons w/helium, tied 'em to a lawn chair and brought along a bb gun for altitude control. If only we'd known we could have handed him a Port pad, Mega Der Red Max and an e controller before he left..I'm sure 'ol Larry could get 'er pretty much vertical?
     
    Last edited: Dec 5, 2019
  30. Dec 5, 2019 #60

    Wallace

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