News Space tourism coming soon!!!

[T.Neo]

As an example the RL-10B2 hydrogen-fueled upper stage engine only has a chamber pressure about 40 bar but because it uses a long nozzle optimized for vacuum use, it gets a vacuum Isp of about 465 s, quite high.

In reality- not quite. The DIRECT study used 459 seconds for the RL-10B-2, and apparently it did not quite reach the ISP goal that was set for it. I may be wrong though, they could have just used the lower value to be conservative.

Then the suborbital companies engines could have orbital Isp's with longer nozzles.

1. Where is the MATH. I can say that I can turn Santa's sleigh into an SSTO too, a claim alone is unfortunately pretty useless.

2. Even with high expansion nozzles propellants have their limitations. Virgin Galactic's hybrid rocket won't have enough performance, XCOR, Blue Origin and Armadillo may have better luck however.

3. You can't just fit a nozzle extension to an engine. This is engineering, and as such there are limitations, practicalities and unknowns.

4. ISP isn't the only consideration in building an orbital vehicle. The suborbital tourism vehicles likely have too low a mass ratio to make orbit, even with higher performance engines.

However, another solution is to use altitude compensation methods.

Why can't you have a two-stager with altitude compensation? It could be very beneficial for a first stage to have altitude compensation.

This solution would make it possible for the suborbital companies to even field low cost SSTO's.

:dry:

Have you ever done a trade study to see if SSTOs really are lower cost than TSTOs?

 

[RGClark]

In reality- not quite. The DIRECT study used 459 seconds for the RL-10B-2, and apparently it did not quite reach the ISP goal that was set for it. I may be wrong though, they could have just used the lower value to be conservative.
1. Where is the MATH. I can say that I can turn Santa's sleigh into an SSTO too, a claim alone is unfortunately pretty useless.
2. Even with high expansion nozzles propellants have their limitations. Virgin Galactic's hybrid rocket won't have enough performance, XCOR, Blue Origin and Armadillo may have better luck however.
3. You can't just fit a nozzle extension to an engine. This is engineering, and as such there are limitations, practicalities and unknowns.
4. ISP isn't the only consideration in building an orbital vehicle. The suborbital tourism vehicles likely have too low a mass ratio to make orbit, even with higher performance engines.

Another example of the fact that the length of the nozzle (actually the nozzle area ratio which is higher for longer nozzles) has a much more important effect than chamber pressure for high vacuum Isp is the example of the SpaceX Merlin engine. The vacuum Isp of the Merlin version used on the first stage is only 304 s. But the Merlin Vacuum which is the same engine with literally just a long nozzle bolted on the standard version gets a 342 s just because of the longer nozzle.
This is a nice report that describes the influence of a longer nozzle:

Advanced Rocket Engines.
Oskar J. Haidn
Institute of Space Propulsion, German Aerospace Center (DLR)
74239 Lampoldshausen Germany
http://ftp.rta.nato.int/public//PubFullText/RTO/EN/RTO-EN-AVT-150///EN-AVT-150-06.pdf

See the attached figure from the report below. As indicated in the figure, the chamber pressure has a relatively small influence on the vacuum Isp, while the nozzle area ratio has a large influence.
To get the high mass ratio for the structures, you could use the balloon tanks that were known about since the 1960's. They were even used to launch astronauts into space with the original Atlas rockets. Balloon tanks are still being used on the Centaur upper stages.
But I doubt you even need that. SpaceX was able to get a 20 to 1 mass ratio for the Falcon 9 without balloon tanks, so it is doable.
BTW, there are various programs available on the net to estimate the performance of rocket engines given some specified parameters on the engine. Most are variations of a government program called ProPEP.
ProPEP is pretty good at least in giving the vacuum Isp of engines by comparing its estimates to the performance of known engines. If you try it you'll find the nozzle area has a much greater influence than the chamber pressure for the vacuum Isp of engines, so that even low chamber pressure engines can get high vacuum Isp with long nozzles.
The original ProPEP was a MS-DOS program; it may not run on the modern Windows computers. You can download it and some other more modern GUI-based versions here:

Software, Simulations, etc.
http://www.spl.ch/software/index.html

There is also this commercial version whose demo version is free:

RPA – Tool for Rocket Propulsion Analysis.
http://www.propulsion-analysis.com/examples.htm


Bob Clark

 

[Arrowstar]

Could we not bring the SSTO debate into this thread, too? :dry:

 

[T.Neo]

Length is secondary, area ratio is key.

And yes, I do actually know a bit about rocketry, but thanks for explaining that anyway.

To get the high mass ratio for the structures, you could use the balloon tanks that were known about since the 1960's.

You can't just engineer balloon tanks into a vehicle structure that is a world away from having huge balloon tanks engineered into it!

SpaceX was able to get a 20 to 1 mass ratio for the Falcon 9 without balloon tanks, so it is doable.

Wrong- the Falcon tanks do use internal pressure to strengthen the tank to withstand flight loads, but they're engineered to be stable on the ground without it.

Could we not bring the SSTO debate into this thread, too?

There is no SSTO debate, but agreed.

 

[RGClark]

Could we not bring the SSTO debate into this thread, too? :dry:

A fair point. My main point is that the suborbital companies are closer to achieving full orbital flight than realized if they use staging.
A key step would be the transition to pump fed engines rather than pressure-fed engines. Armadillo Aerospace, Masten Space Systems, and I believe also SpaceShipOne use pressure-fed engines (for the oxidizer for the hybrid engines on SpaceShipOne.)
I know that for XCOR they will use pump fed engines. I'm not sure about the engines on Blue Origin.
Pressure fed engines are much simpler, but they result in poor mass ratios because the entire tank has to be at the high pressure of the combustion chamber. This requires thicker tank walls to hold the high pressure and therefore significantly heavier tanks.

Bob Clark

 

[T.Neo]

My main point is that the suborbital companies are closer to achieving full orbital flight than realized if they use staging.

They aren't close at all. What about the other issues of making an orbital vehicle? You need a proper TPS, for one... and you need power for on-orbit... as thermal control, extra supplies, etc.

 

[RGClark]

Armadillo Aerospace has now succeeded in launching their rocket to high altitude:

Armadillo Launches STIG A Rocket to 137,500 Feet From Spaceport America
Posted by Doug Messier on December 6, 2011, at 12:31 pm in News.
http://www.parabolicarc.com/2011/12...rocket-to-124000-feet-from-spaceport-america/

Armadillo Stiga rocket high altitude launch to nearspace - YouTube

Congrats to Armadillo and John Carmack. They apparently have solved the problem of instability at high velocity. No doubt getting to the full altitude for space at 100 km will come in short order as well. :thumbup:


Bob Clark

Armadillo has succeeded in a second launch, this time to 82 km. They expect to reach the altitude for "space" at 100 km sometime this spring.

Armadillo Launches a STIG-A Rocket; Captures Awesome Image of ‘Ballute’.
by NANCY ATKINSON on FEBRUARY 2, 2012
http://www.universetoday.com/93281/...g-a-rocket-captures-awesome-image-of-ballute/


Bob Clark

 

[Izack]

Reaching space << getting into space. :2cents:

The images in that article look like they were taken from a few hundred miles, not fifty!

Still, best of luck to them. Would be cool to see them actually reach orbit in ten or twenty years...

 

[orb]

Aviation Week: U.S. Space Tourism Set for Takeoff by 2014: FAA:

The Obama administration is preparing for a space tourism industry that is expected to be worth $1 billion in 10 years, the head of the Federal Aviation Administration’s commercial space office said March 20.

Rocket planes and spaceships to carry passengers beyond the atmosphere, similar to the suborbital hops taken by Mercury astronauts Alan Shepard and Virgil “Gus” Grissom in 1961, are being built and tested, with commercial flight services targeted to begin in 2013 or 2014.

“Based on market studies, we expect to see this type of activity result in a $1 billion industry within the next 10 years,” George Nield, associate administrator for the FAA’s Office of Commercial Space Transportation testified before the House Subcommittee on Space and Aeronautics.

“This is a new and growing industry. If you look at the last 25 years, almost all the launches were for the same basic purposes - to launch a satellite, such as a telecommunications satellite, to orbit - and that level of business for that part of the industry is continuing today. But there are several new segments that we see just on the horizon,” Nield said.

The boom in launch business is expected to begin this year, he said in the hearing, which was carried via webcast.

{...}

Florida Today: Private space launches should see boost this year

 

[orb]

Florida Today: Space tourism might be a hit; demand rising:

WASHINGTON — Commercial spaceflight is not only possible, it could become a $1.6 billion industry in the next decade, a researcher told Congress on Wednesday.

Carissa Bryce Christensen of the Tauri Group said 925 reservations for suborbital trips already have been purchased. Some customers have paid the full $200,000 cost in advance, while others have put down a $20,000 deposit.

The Tauri Group and the Federal Aviation Administration released a joint study that found demand at these prices to be “genuine, sustained, and ... sufficient to support multiple providers.”

Six private companies work in the suborbital reusable launch vehicle market. None has launched commercially yet, but at least two — Virgin Galactic and XCOR Aerospace — plan to start flights at the end of 2013.

The vehicles are designed to travel into space for scientific research or tourism, but can’t orbit the Earth.

“Space flights have been very rare since its inception. They are about to become routine,” Alan Stern, chairman of the Suborbital Applications Researchers Group, told members of the House Science, Space and Technology Subcommittee on Space and Aeronautics.

According to the study, there will be enough demand for such flights to fill 400 to 500 seats per year. That number could triple if demand increases, or be cut in half if it plummets.

“Additional potential demand is possible from unknowns such as research discoveries, commercial applications or a viral consumer response,” Christensen told lawmakers. “Price reductions would also increase demand.”

{...}

 

[boogabooga]

XCOR Lynx in the news:

http://gma.yahoo.com/blogs/abc-blog...mmercial-flight-100042086--abc-news-tech.html

To that end, Nelson believes that within eight to 10 years, aircraft like the Lynx could be bringing astronauts to the international space station and back.

Wow, a real life delta glider!
And they will get here just as the ISS is about to retire

 

[IronRain]

My view of the Lynx:
[ame="http://www.orbithangar.com/searchid.php?ID=1030"]Dyna-Soar w/MOOSE v1.34[/ame] NextGen.

 

[MattBaker]

So, I've just read about Armadillo Aerospace dying.

Which once again lead me to the question if that's one of the early private space companies going down the drain?
At least the concepts always seem similar, rich guy starting a company, testing, naturally some trouble while testing, trouble is the end of the company.


Although at least a couple of private companies have already made it over that edge and try the "become fully private" one now...

 

[Alfastar]

Necroposting because...because I can?


So, I've just read about Armadillo Aerospace dying.

Which once again lead me to the question if that's one of the early private space companies going down the drain?
At least the concepts always seem similar, rich guy starting a company, testing, naturally some trouble while testing, trouble is the end of the company.


Although at least a couple of private companies have already made it over that edge and try the "become fully private" one now...

Well, I think we see a few 'private' spaceflight companies in about 10 years. Its now hip to be as a rich person making some fame with the new toy: Spaceflight. But that toy is in fact expensive and only works good if you doing it good, and that does most 'private' spaceflight companies in this time not. I can serious become tired if I hear people saying by every new private spaceflight group / company: "Its the future, and there going to beat NASA and make all our wishes true and it become cheaper then everything before". But at the same time when NASA cuts on private spaceflight projects: "NASA don't give them a chance, you never must cut on things like that because its bad for the private spaceflight sector"

And that is something what let my facepalming my.

 

[jedidia]

Wait... their development budget was so tight that it couldn't accommodate the loss of one prototype? That's ludicrous. You know you'll loose prototypes. There's better chances of winning the lottery than to make it from blueprint to finished product without losing a prototype or two...

 

[orb]

Necroposting because...because I can?

Because this isn't necroposting, as stated by the rules.

 

[Urwumpe]

Wait... their development budget was so tight that it couldn't accommodate the loss of one prototype? That's ludicrous. You know you'll loose prototypes. There's better chances of winning the lottery than to make it from blueprint to finished product without losing a prototype or two...

I think the reality is different: AA was the hobby project of Carmack, and his hobby has started to become a job. Thats all. He funded the show, nobody else wants to fund it in the same way, so it has to die. Sad, but correct.

I would really wish AA could operate in a different way or as non-profit organization, but I don't see that.

 

[Dantassii]

My thoughts

I see space tourism today as being at the same level as heavier than air aviation was the time that the Wright Brothers figured it out. There were MANY inventors trying to do what they did. Several were just guys with WAY too much money and nothing to spend it on. Many had hair brained ideas that we know today would never work, but they tried them anyway. Even after the Wright Brothers showed everyone how it could be done, there were guys who couldn't figure out how they had done it and tried to do it other ways, and some even succeeded, but most failed. Many lives were lost and fortunes expended during this time, but that was expected because the technology was very immature.

Will prototypes be lost in the quest for regular, inexpensive, manned access to suborbital flight? Definitely. Will lives be lost? Possibly. Will fortunes be expended with nothing to show for it. Positively!

Will regular, inexpensive, manned access to suborbital flight become a real part of the everyday human experience within the next 20-50 years? Absolutely yes, no doubt about it.

 

[Alfastar]

I see space tourism today as being at the same level as heavier than air aviation was the time that the Wright Brothers figured it out. There were MANY inventors trying to do what they did. Several were just guys with WAY too much money and nothing to spend it on. Many had hair brained ideas that we know today would never work, but they tried them anyway. Even after the Wright Brothers showed everyone how it could be done, there were guys who couldn't figure out how they had done it and tried to do it other ways, and some even succeeded, but most failed. Many lives were lost and fortunes expended during this time, but that was expected because the technology was very immature.

Will prototypes be lost in the quest for regular, inexpensive, manned access to suborbital flight? Definitely. Will lives be lost? Possibly. Will fortunes be expended with nothing to show for it. Positively!

Will regular, inexpensive, manned access to suborbital flight become a real part of the everyday human experience within the next 20-50 years? Absolutely yes, no doubt about it.

I hear that point so much that people compare the battle of private spaceflight is the same as the birth of aviation. Even space tourism is older then this time where SpaceX (And Virgin galactic rules the headlines. You would missing a big point that space tourism is already done thanks by a few Soyuz flights to the ISS with a tourist as one of the crew.

Also, spaceflight is still a lot more harder to do then most think. Its just not push a button and let the rocket go. You need people who known what there do, you need a good rocket with a good rocket engine, you need a tons of other things to let a rocket launch be a success. Serious, if I must tell all of the things you need to serious launch something into space, then I are not done today with writing.

 

[Dantassii]

I'm just saying that IMHO we are still about 20-50 years away from regular, inexpensive, manned suborbital flight. Spending as much for 1 flight as a house costs is not my idea of regular, inexpensive, manned suborbital flight. When they get it down to under $1500 per passenger per flight (the cost of an expensive, first class ticket on a long airline flight, plus extras), then I will believe that regular, inexpensive, manned suborbital flight has arrived. Until then, it's a thing for the inventors, innovators, and simply people with lots of money and no idea what to spend it on. I just wish I could be one of them....