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Thread: Space flight on the cheap.

  1. #1 Space flight on the cheap. 
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    Would it be possible and of any benefit to lift a small rocket with a payload to the upper 99% percent of our atmosphere using a high altitude balloon, the rocket would detach in the upper atmosphere at around 26 miles, drop and ignite. Flight stability will be an issue just after ignition, without a launch platform.

    Maybe the balloon could have a tubular tunnel through the middle of it to allow the rocket to pass through. I doubt the balloon could handle the downward thrust of the rocket though.

    Or it could drop and glide, then slowly increase the thrust and speed.

    NASA's large balloons can carry a payload weighing as much as 3,600 kilograms (8,000 pounds), about the weight of three small cars. They can fly up to 42 kilometers (26 miles) high and stay there for up to two weeks.


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  3. #2 Re: Space flight on the cheap. 
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    Quote Originally Posted by Lost(in)thought
    Would it be possible and of any benefit to lift a small rocket with a payload to the upper 99% percent of our atmosphere using a high altitude balloon, the rocket would detach in the upper atmosphere at around 26 miles, drop and ignite. Flight stability will be an issue just after ignition, without a launch platform.

    Maybe the balloon could have a tubular tunnel through the middle of it to allow the rocket to pass through. I doubt the balloon could handle the downward thrust of the rocket though.

    Or it could drop and glide, then slowly increase the thrust and speed.

    NASA's large balloons can carry a payload weighing as much as 3,600 kilograms (8,000 pounds), about the weight of three small cars. They can fly up to 42 kilometers (26 miles) high and stay there for up to two weeks.
    Possible, maybe. Feasible, probably not.

    Rockets tend to be fairly heavy -- Each shuttle solid booster is well over a million pounds for instance, so you would need a really big balloon.

    The issue in getting pounds to orbit is achieving orbital speed more so than just achieving altitude (obviously both are required). Getting a step up by launching at 100,000 feet or so would reduce loss due to aerodynamic drag, but only get you about 20% of the way to low earth orbit, at 0 speed. A typical first stage boost gets to about that altitude, or higher, but at hypersonic speeds.

    What can help is launch from an aircraft which provides both altitude and some speed. Pegasus does just that, but payloads are small.


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  4. #3  
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    We have 8,000 pounds in this model to work with, would it even be possible without a payload? If not how much balloon lift would we need?
    This idea is something that I have been thinking about over the years. I wondered if it could have been used in that civilian space contest. Thank you for your valued thoughts.
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  5. #4  
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    Quote Originally Posted by Lost(in)thought
    We have 8,000 pounds in this model to work with, would it even be possible without a payload? If not how much balloon lift would we need?
    This idea is something that I have been thinking about over the years. I wondered if it could have been used in that civilian space contest. Thank you for your valued thoughts.
    You need to be more clear. 8000 pounds of what ? 8000 lb is a very small rochet.

    Which civilian space contest ?
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  6. #5  
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by Lost(in)thought
    We have 8,000 pounds in this model to work with, would it even be possible without a payload? If not how much balloon lift would we need?
    This idea is something that I have been thinking about over the years. I wondered if it could have been used in that civilian space contest. Thank you for your valued thoughts.
    You need to be more clear. 8000 pounds of what ? 8000 lb is a very small rochet.

    Metallic hydrogen LOX Rocket ( haha )

    Which civilian space contest ?
    The Ansari X Prize

    Winner of the $10,000,000 prize was SpaceShipOne.

    SpaceShipOnes specifications

    Crew: one, pilot
    Capacity: 2 passengers
    Length: 16 ft 5 in (8,05 m)
    Wingspan: 16 ft 5 in (8,05 m)
    Height: ()
    Wing area: 161.4 ft (15 m)
    Empty weight: 2,640 lb (1,200 kg)
    Loaded weight: 7,920 lb (3,600 kg)
    Powerplant: 1 N2O/HTPB SpaceDev Hybrid rocket motor, 7,500 kgf (74 kN)
    Isp: 250 s (2450 Ns/kg)
    Burn time: 87 seconds
    Aspect Ratio: 1.6
    Performance
    Maximum speed: Mach 3.09 (2,170 mph, 3,518 km/h)
    Range: 35 nm (40 mi, 65 km)
    Service ceiling: 367,360 ft (112,000 m)
    Rate of climb: 82,000 ft/min (416.6 m/s)
    Wing loading: 49.07 lb/ft (240 kg/m)
    Thrust/weight: 2.08
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  7. #6  
    . DrRocket's Avatar
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    Quote Originally Posted by Lost(in)thought
    Quote Originally Posted by DrRocket
    Quote Originally Posted by Lost(in)thought
    We have 8,000 pounds in this model to work with, would it even be possible without a payload? If not how much balloon lift would we need?
    This idea is something that I have been thinking about over the years. I wondered if it could have been used in that civilian space contest. Thank you for your valued thoughts.
    You need to be more clear. 8000 pounds of what ? 8000 lb is a very small rochet.

    Metallic hydrogen LOX Rocket ( haha )

    Which civilian space contest ?
    The Ansari X Prize

    Winner of the $10,000,000 prize was SpaceShipOne.

    SpaceShipOnes specifications

    Crew: one, pilot
    Capacity: 2 passengers
    Length: 16 ft 5 in (8,05 m)
    Wingspan: 16 ft 5 in (8,05 m)
    Height: ()
    Wing area: 161.4 ft (15 m)
    Empty weight: 2,640 lb (1,200 kg)
    Loaded weight: 7,920 lb (3,600 kg)
    Powerplant: 1 N2O/HTPB SpaceDev Hybrid rocket motor, 7,500 kgf (74 kN)
    Isp: 250 s (2450 Ns/kg)
    Burn time: 87 seconds
    Aspect Ratio: 1.6
    Performance
    Maximum speed: Mach 3.09 (2,170 mph, 3,518 km/h)
    Range: 35 nm (40 mi, 65 km)
    Service ceiling: 367,360 ft (112,000 m)
    Rate of climb: 82,000 ft/min (416.6 m/s)
    Wing loading: 49.07 lb/ft (240 kg/m)
    Thrust/weight: 2.08
    Spaceshipone was suborbital.

    The open X Prize is for a moon landing with a rover. The prize is $20 million. That won't begin to cover costs.
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  8. #7  
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    Lets say that we lift the SpaceShipOne to 26 miles above sea level and then released it, would it have any chance of reaching and maintaining an orbit?


    SpaceShipOne's specifications:

    Crew: one, pilot
    Capacity: 2 passengers
    Length: 16 ft 5 in (8,05 m)
    Wingspan: 16 ft 5 in (8,05 m)
    Height: ()
    Wing area: 161.4 ft (15 m)
    Empty weight: 2,640 lb (1,200 kg)
    Loaded weight: 7,920 lb (3,600 kg)
    Powerplant: 1 N2O/HTPB SpaceDev Hybrid rocket motor, 7,500 kgf (74 kN)
    Isp: 250 s (2450 Ns/kg)
    Burn time: 87 seconds
    Aspect Ratio: 1.6
    Performance
    Maximum speed: Mach 3.09 (2,170 mph, 3,518 km/h)
    Range: 35 nm (40 mi, 65 km)
    Service ceiling: 367,360 ft (112,000 m)
    Rate of climb: 82,000 ft/min (416.6 m/s)
    Wing loading: 49.07 lb/ft (240 kg/m)
    Thrust/weight: 2.08
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  9. #8  
    Universal Mind John Galt's Avatar
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    2,170 mph is not sufficient to maintain orbit. Orbital velocity is around 17,000 mph for low Earth orbit.
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  10. #9  
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    I think it's pretty much impossible to achieve orbit with an ISP of only 250. You would need like 99 kg of fuel for every kg of rocket.
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  11. #10  
    Forum Cosmic Wizard icewendigo's Avatar
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    Ok how about this

    I was told that a giant maglev mountain side mass driver would face the problem (besides its cost) of extreme friction the second it exited the (presumably depressurized) mass driver tube

    what if the mass driver tube propelling the rocket craft ended up being connected to a really really long and high tubular air balloon? (its ok if you get a laugh) designed to reduce air pressure as much as possible along the first few km?

    and while I'm on the crazy idea road, and that it requires a lot of rocket fuel to get the rocket fuel itself off the ground...

    what if 4 very resilient armored side cones were peppered by 4 machine gun fire steams of rocket fuel pellets in the initial stage of a rocket? Could you save rocket fuel by propelling some of it directly from the ground up istead of carrying it in the rocket's fuel tank? (or would you just save the equivalent of the gunpowder used to propell it to the in flight altitude)?
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  12. #11  
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    Quote Originally Posted by Scifor Refugee
    I think it's pretty much impossible to achieve orbit with an ISP of only 250. You would need like 99 kg of fuel for every kg of rocket.
    That depends on how you use it, although 250 s Isp is really low.

    Typical solid booster Isp is abut 272 s (theoretical at sea level}, with a mass fraction at the booster level of on the order of 95% (propellant to inerts). That is nowhere near sufficient for a single-stsge-to-orbit (SSTO) design. In fact there is no current propulsion technology that will give you a viable SSTO.

    Lox/hydrogen Isp is on the order of 440 s, but the mass fraction is pretty low, which is why the shuttle gets most of its initial boost from the solid strap-ons.

    That is why current launchers are multi-stage designs. Now no good designer would start with a 250s Isp booster, but the sensitivity of om-orbit payload to Isp is much less for first stage motors than for upper stage motors (the same statement applies to mass fraction). So, you might be able to make something with such lousy performance work in a first stage -- though I don't know why one would want to.

    I don't know what SpaceDev did to get such lousy Isp from a hybrid. Hybrids have all sorts of problems and combustion issues, but one ought to get something better than 300 s Isp without trying very hard.
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