Author Topic: Stratospheric-Airship-Assisted Orbital Payload Launching System  (Read 3298 times)

Offline saaopl

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Stratospheric-airship-assisted orbital payload launching (SAAOPL) system is a newly-designed HTHL reusable launching system. Distinct from conventional HTHL concepts, SAAOPL combines stratospheric launch with HTHL reusable launch vehicle. SAAOPL employs a mixed structure of balloon and airship as its stratospheric launch platform. To swiftly offload the extra buoyancy, the launch platform of SAAOPL is inflated with hydrogen and helium lifting gas in its ascent but completely vent hydrogen lifting gas after the HTHL reusable vehicle is launched.

Features of SAAOPL includes: 1 Reusability, the whole SAAOPL system can be reusable; 2 Reliablilty: SAAOPL system is able to bring its payload back in launch failures; 3 Short launch cycle: the next mission can be ready in 8 hours from the starting point of current mission, if using the same system.

Launch cycle:


Brief CG introduction: (conceptual design)


Official site (still under development)
http://saaopl.net/
« Last Edit: 04/03/2017 01:35 AM by saaopl »
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Offline aceshigh

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That looks like a very tiny fuel tank to achieve a delta-v of 30 thousand km per hour.

Offline saaopl

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Firstly, I should put a note here that this is more a conceptual representation than a detailed design.

Secondly, SLSS, as the third word of its name (Suborbital) states,  doesn't reach orbital speed. For example, in a sample simulation for regional flight profile, SLSS reaches around 15 Mach speed and 112 km altitude at burn-out.

Thanks for your interest and question!

 
Earth is the cradle of humanity, but one cannot live in a cradle forever  -- Konstantin Tsiolkovsky

Offline mikelepage

Hey, welcome to the site, and great effort on your first post.

I used to love stuff like this, but the math doesn't work out, unfortunately (like, not even close - sorry).  You struggle to launch cubesats this way, unless you build the biggest airship in history, and that's not an economical way to cover the first 50km.

There is a reason Falcon 9 is the size of small skyscraper.

Offline saaopl

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Thanks, Mike!

SAAOPL is designed to replace expandable launch system mostly using existing technologies. While SpaceX is taking VTVL approach, SAAOPL is based on HTHL but combined with stratospheric launch. 

Yes, as you guessed, the launch platform would be the largest aircraft in history. In a conceptual implementation that used to investigate its feability, the length of balloon/airship platform is almost three times that of Zeppelin,  if it is full expanded at 22.3km altitude. However, constructing such platform is not as difficult as it looks, given its low speed nature and Zylon already satisfies the strength requirement for envelope material (if my model and calculation are correct). 
« Last Edit: 04/04/2017 12:42 PM by saaopl »
Earth is the cradle of humanity, but one cannot live in a cradle forever  -- Konstantin Tsiolkovsky

Offline Jim

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The airship provides little benefit.  launch velocity is more important than launch altitude

Offline sevenperforce

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The airship provides little benefit.  launch velocity is more important than launch altitude
Aye, the only meaningful advantage of launching from altitude is the ability to use near-vacuum-optimized engines from the start, but if you're already planning on staging to at least some degree, it's a lot of trouble for very little return.

SAAOPL is designed to replace expandable launch system mostly using existing technologies. While SpaceX is taking VTVL approach, SAAOPL is based on HTHL but combined with stratospheric launch.
SAAOPL, it would seem, IS an "expandable" launch system.
« Last Edit: 04/04/2017 05:30 PM by sevenperforce »

Offline Tulse

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Aye, the only meaningful advantage of launching from altitude is the ability to use near-vacuum-optimized engines from the start
Are there any advantages to having a much more benign aerodynamic environment (e.g., far lower max Q)?  Would that allow a lighter structure for the actual vehicle, and thus better performance?  If one doesn't have to worry about dense atmosphere, and thus streamlining, does that allow different form factors for the vehicle rather than a slender tube?

Offline Jim

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Aye, the only meaningful advantage of launching from altitude is the ability to use near-vacuum-optimized engines from the start
Are there any advantages to having a much more benign aerodynamic environment (e.g., far lower max Q)?  Would that allow a lighter structure for the actual vehicle, and thus better performance?  If one doesn't have to worry about dense atmosphere, and thus streamlining, does that allow different form factors for the vehicle rather than a slender tube?

No, since there still is enough to matter

Offline Jim

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Short launch cycle: the next mission can be ready in 8 hours from the starting point of current mission, if using the same system.



The airship round trip flight is going take more than that

Offline saaopl

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The airship provides little benefit.  launch velocity is more important than launch altitude

Hi Jim,

If you are talking about bringing a conventional rocket to stratosphere by airship and launching it vertically, I agree with your point. Yes, the performance gain brought by high altitude is marginal. Benefits brought by high altitude and the boost of engine thrust and ISP are not as dramatic as thought.

However, when it comes with Winged SLSS, the scenario will be different. You can check the following table for reference.

Advantages of stratospheric launch over conventional vertical lift-off have been summarized on the following page:
http://saaopl.net/index.php/features/
« Last Edit: 04/05/2017 02:22 AM by saaopl »
Earth is the cradle of humanity, but one cannot live in a cradle forever  -- Konstantin Tsiolkovsky

Offline saaopl

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Quote
The airship round trip flight is going take more than that

I agree with your point about conventional airship, but stratospheric launch platform isn't a conventional airship. A key idea of the stratospheric launch platform is that it is mixed structure of balloon and airship.

In its ascent and descent stages, the stratospheric launch platform is more like a balloon. Its buoyancy is much larger than its weight in ascent stage, and the reverse holds in its descent stage.

Taking ascent stage for example, hydrogen ballonet is partially folded to minimize its cross-section area and more hydrogen is inflated to provide extra lifting force, to speeds up the platform's unpropelled and unsteered free ascent. The platform's ascent speed can be around 18km/hour on average.

Rapid ascent/descent will help the system to minimize the influence of meteorological activities in troposphere, and lower the working load for position correction when the platform approaches the launching altitude or gets close to ground. 

For more information, you can take a look the following pages
http://saaopl.net/index.php/build/
http://saaopl.net/index.php/flight/


« Last Edit: 04/05/2017 02:48 AM by saaopl »
Earth is the cradle of humanity, but one cannot live in a cradle forever  -- Konstantin Tsiolkovsky

Offline mikelepage

Best quote I've heard lately is
"Fall in love with your customer's problems, not your own solutions."

I'm assuming you've seen this, but if not you'll be interested:
http://aeroscraft.com/aeroscraft/4575666071
http://aeroscraft.com/fleet-copy/4580475518

The biggest planned aeroscraft has a payload of 500 tons.
The smallest orbital launcher I've heard of (Rocketlabs Electron) has a liftoff mass of 10 tons with a payload to orbit of 150kg.  So in theory, a heavily modified version of the aeroscraft could launch the 10 ton rocket from up to 30km altitude.

However, whether you launch the rocket from an altitude of 0km, or of 30km, it still has to go from 0km/s to 8km/s in velocity.  That's the killer.  It's analogous to the question of how much further a baseball pitcher can throw the ball if his mound is another meter higher?  By using stratospheric launch, your "pitcher's mound" might be 30km up, but remember that the Earth is 40,000 km around.  The extra altitude makes little to no difference and adds a ton of complications (e.g. all the equipment you need to keep the liquid oxygen liquid is heavy, so your airship gets even bigger)

There are some problems where large airships are elegant solutions.  Space launch is not one of them.

You've got some great web developer skills though, so hopefully developing this site will help you work on others in the future.

Offline as58

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Best quote I've heard lately is
"Fall in love with your customer's problems, not your own solutions."

That is a very good guideline. Unfortunately, by the time someone asks for comments (especially in an Internet forum), the falling in love with the solution has often already happened.

Offline saaopl

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whether you launch the rocket from an altitude of 0km, or of 30km, it still has to go from 0km/s to 8km/s in velocity.

The stratospheric launch platform doesn't add delta-V to SLSS directly. Instead, the altitude it provides and corresponding low air density, will help reducing steering loss, gravity drag, aerodynamic drag and Max-Q.  Engine will receive a performance gain due to low ambient pressure.  You can take a look at the post I replied to Jim, and the flowing page:
http://saaopl.net/index.php/features/

Besides, altitude provided by launch platform can boost robustness of SAAOPL system. As mentioned on the official site, if an engine failure occurs shortly after launch, the SLSS has sufficient altitude redundancy, which is provided by the launch platform, to safely dump all its fuel and glide to an airfield nearby with its payload. In other words, both SAAOPL system and payload can be intactly saved in an engine failure scenario.


e.g. all the equipment you need to keep the liquid oxygen liquid is heavy
 

The platform is equipped with liquid nitrogen (LN2) tank. LN2 is used to cool down liquid oxygen (LOX) in SLSS. Vaporized nitrogen gas is either released to create an inert environment around the service module, or harvested to help removing hydrogen residue in hydrogen ballonet later on. Since it takes the launch platform around 2 hours from lift-off to launching SLSS, the amount of LN2 needed for cooling LOX isn't large. I have provided a description on the following page:
http://saaopl.net/index.php/build/

Thx!
« Last Edit: 04/06/2017 02:06 AM by saaopl »
Earth is the cradle of humanity, but one cannot live in a cradle forever  -- Konstantin Tsiolkovsky

Offline mikelepage

There was a Q&A at Aviation week some while back and this https://en.wikipedia.org/wiki/Air_launch_to_orbit was Elon Musk's response to another air launch concept involving a plane, but it could equally well apply to your platform:

Quote
"…it seems like...you're high up there and so surely that's good and you're going at...0.7 or 0.8 Mach and you've got some speed and altitude, you can use a higher expansion ratio on the nozzle, doesn't all that add up to a meaningful improvement in payload to orbit?

"The answer is no, it does not, unfortunately. It's quite a small improvement. It's maybe a 5% improvement in payload to orbit...and then you've got this humungous plane airship to deal with. Which is just like having a stage. From SpaceX's standpoint, would it make more sense to have a gigantic plane airship or to increase the size of the first stage by five percent? Uhh, I'll take option two."

Emphasis/mods mine, and like I said before, the math (edit: of the whole system) doesn't work out unfortunately. 
« Last Edit: 04/06/2017 05:42 AM by mikelepage »

Offline saaopl

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There was a Q&A at Aviation week some while back and this https://en.wikipedia.org/wiki/Air_launch_to_orbit was Elon Musk's response to another air launch concept involving a plane, but it could equally well apply to your platform:

I actually shared Musk's view towards conventional air-launch approaches. In the AQ section of the following page, brief comments on two conventional air launch by plane and by balloon approaches have already been included.
http://saaopl.net/index.php/features/

One major reason that two conventional air launch are not promising, and yet to be mentioned by Musk, is that none of them are reusable, or neither of them can be an ideal candidate to develop a reusable launch system. Still both of them have already paid the dry mass and complexity that should be used for reusability.

Distinct from two aforementioned air-launch systems, SAAOPL conceptually avoids the limitations or even drawbacks of these two. As summarized in the official site and also demonstrated in simulations, SAAOPL system will receive a substantial performance gain that can well pay off the dry mass and complexity penalty due to the reusability. It includes new features in design, but inherit technologies and hardware of Space Shuttle, SR-71 and HAAs. 

The aim, as mentioned earlier in this thread, is to develop a reusable, reliable and also short-launch-cycle system as the next generation launching system. While SpaceX is taking VTVL approach, SAAOPL system is based on HTHL system, but learned lessons from previous HTHL systems and concepts.
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Offline Kansan52

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Offline saaopl

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Maybe replace the airship with this:

https://www.nasa.gov/centers/armstrong/Features/TGALS_first_flight.html


It is basically air-launch by plane, alleviates volume-capacity issue but sacrifices performance of plane. It has most issues of air-launch by plane.
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Online ChrisWilson68

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There was a Q&A at Aviation week some while back and this https://en.wikipedia.org/wiki/Air_launch_to_orbit was Elon Musk's response to another air launch concept involving a plane, but it could equally well apply to your platform:

I actually shared Musk's view towards conventional air-launch approaches. In the AQ section of the following page, brief comments on two conventional air launch by plane and by balloon approaches have already been included.
http://saaopl.net/index.php/features/

One major reason that two conventional air launch are not promising, and yet to be mentioned by Musk, is that none of them are reusable, or neither of them can be an ideal candidate to develop a reusable launch system.

Actually, if you'll read the quote above from Musk it doesn't mention reusability at all.  Musk's point is valid even if you have full reusability.

Musk's point is that an aircraft-launched system essentially makes the aircraft an additional stage.  You have all the cost and complexity of an additional stage, but it's an additional stage that gives you much less benefit than a rocket stage.  The same is true for an airship-assisted launch system -- the airship is an additional stage, but one that gives you much less benefit than a rocket first stage.

You didn't address this point in your reply.

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