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Suborital intercontinental travel

Posted by: WarKosign - Sun Sep 06, 2009 7:26 pm
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Suborital intercontinental travel 
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Post Suborital intercontinental travel   Posted on: Sun Sep 06, 2009 7:26 pm
Do you think suborbital space travel can be used for intercontinental travel, rather than a form of extreme sport or testing platform for orbital flight development ?

Assuming the 6-pack is capable of taking 2 people up to 100km, with some additional fuel it should be able to take the trajectory at some angle to the desired direction, gaining much more horizontal speed as the vehicle rises above the dense parts of the atmosphere, and landing at some distant spaceport across the ocean.

At first it will probably be as expensive as space tourism, but can it become a real competition to regular jet flights ?

On one hand, the vehicle has to be taken much higher, thus burning much more fuel - but on the other hand, one doesn't have to keep the vehicle in the air for hours the way it's done with planes - there has to be some benefit in it.


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Post Re: Suborital intercontinental travel   Posted on: Mon Sep 07, 2009 9:50 am
I'm not an expert, but I believe that suborbital spaceplanes like SpaceShipTwo or Lynx are much more suited to suborbital intercontinental travel.

If I remember correctly, VirginGalactic has intercontinental passenger flights as a furture goal in case the space tourism business proves sucessful.

Personally I can't wait to see this happen!

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Post Re: Suborital intercontinental travel   Posted on: Mon Sep 07, 2009 6:08 pm
But the volume will be so low (until very large vessels are produced in quantity), that the cost will be pretty huge. Doesn't make much sense if you're just trying to get from A to B.


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Post Re: Suborital intercontinental travel   Posted on: Mon Sep 07, 2009 10:25 pm
WarKosign wrote:
On one hand, the vehicle has to be taken much higher, thus burning much more fuel - but on the other hand, one doesn't have to keep the vehicle in the air for hours the way it's done with planes - there has to be some benefit in it.


If you are talking across an ocean then you are getting up to 80 or 90% of the energy of an *orbital* flight.

It actually ends up being somewhat harder than orbit because instead of spending 4 minutes re-entering, you spend 20 minutes or more in super-heated atmosphere.

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Post Intercontinental Rocket Racing Prize?   Posted on: Wed Sep 16, 2009 1:29 am
But at the same time, isn't the near-to-medium term market potential for intercontinental travel/transport greater than for spaceflight? In today's increasingly global economy, aren't there more people than ever trying to get from New York to Beijing, or from London to Tokyo, etc, etc?

I realize that the general civilian market would be far more price-sensitive, but it's a matter of calculating the highest ticket price that the market would bear, and then striving to engineer toward that goal.

I've read about upcoming private jets like QSST, and those are only going to be barely supersonic.

Perhaps that Rocket-Racing competition idea could be adapted towards fastest intercontinental flight.
Whoever could fly fastest from, say, Daytona over to the Isle of Man, would win a prize.
That kind of race would be a lot more conducive to getting off the planet than the Indy500. If you kept holding it every year with a reasonable number of participants, people would keep pushing the envelope, and it would only be a matter of time before someone reached hypersonic velocity, even if they ended up sitting inside a flying missile.


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Post Re: Suborital intercontinental travel   Posted on: Wed Sep 16, 2009 11:16 am
Agreed. With wings, at least you can continue to glide for a while until you find a safer spot to land than right here.

Still, the world is big enough to accommodate the RRL, transatlantic speed races and suborbital transportation all at once. Actually, if they were all happening around the same time, that would generate some excitement and therefore demand, I think.


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Post Re: Suborital intercontinental travel   Posted on: Wed Sep 16, 2009 6:02 pm
idiom wrote:
If you are talking across an ocean then you are getting up to 80 or 90% of the energy of an *orbital* flight.

It actually ends up being somewhat harder than orbit because instead of spending 4 minutes re-entering, you spend 20 minutes or more in super-heated atmosphere.


80 or 90% of orbital? How do you figure this? And the 'super heated' atmosphere depends on the crafts velocity and/or deceleration. You really think its going to experience 2000 degrees fahrenheit on reentry?

The craft won't be going 17000 miles an hour, much less.


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Post Re: Suborital intercontinental travel   Posted on: Wed Sep 16, 2009 6:20 pm
ICBMs are suborbital. I assume they used altitude to minimize the time in heat build up on reentry.

There is more than one way to skin a rabbit. The problem is nobody has done this. Only ICBMs have been studied for this as operational vehicles. And I think there is lots of room for creative thinking here.

The difference between suborbital straight up and down and suborbital travel is basically horizontal velocity (following contour of the earth). Then there is the obstacle of reentry. SpaceShipOne pioneered a new way of reentry for manned spacecraft. Which needs less heat shield. The thing is with stub wings you need to land almost on top of your target.

I'm sure when most people look at this problem they use Space Shuttle as a baseline. But I think that this is a mistake in that the Shuttle is an orbital spacecraft. The problem really requires a whole new set of variables and a whole new space craft. Something between the shuttle and SpaceShipOne.


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Post Re: Suborital intercontinental travel   Posted on: Wed Sep 16, 2009 8:00 pm
ralpher05 wrote:
80 or 90% of orbital? How do you figure this? And the 'super heated' atmosphere depends on the crafts velocity and/or deceleration. You really think its going to experience 2000 degrees fahrenheit on reentry?

The craft won't be going 17000 miles an hour, much less.


Then it won't be doing Atlantic crossings in 45 minutes.

Better baseline aircraft would be the Concorde, SR - 71 and the X-15. To get above mach 3.2 you have to start getting right out of the atmosphere to avoid heating and that means you are no longer flying a lifting vehicle but either a ballistic or skipping vehicle. Both flight types are highly energetic and get their energy added early. A trans-atlantic flight on a ballistic profile is only a wee bit shy of an orbital profile. The Space Shuttle, to use your example, doesn't have enough energy to get across the atlantic until 30 seconds after the SRB's have burnt out.

While there is a market for it, it is a complex market and you start playing with really expensive things like international certifications.

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Post Re: Suborital intercontinental travel   Posted on: Thu Sep 17, 2009 1:38 am
idiom wrote:
Then it won't be doing Atlantic crossings in 45 minutes.

Better baseline aircraft would be the Concorde, SR - 71 and the X-15. To get above mach 3.2 you have to start getting right out of the atmosphere to avoid heating and that means you are no longer flying a lifting vehicle but either a ballistic or skipping vehicle. Both flight types are highly energetic and get their energy added early. A trans-atlantic flight on a ballistic profile is only a wee bit shy of an orbital profile. The Space Shuttle, to use your example, doesn't have enough energy to get across the atlantic until 30 seconds after the SRB's have burnt out.

While there is a market for it, it is a complex market and you start playing with really expensive things like international certifications.


If the craft is going 17000 miles an hour on the horizontal its not just crossing the Atlantic, its in orbit. I don't think you absolutely have to cross the atlantic in 45 minutes. There's nothing flying right now that can cross it in an hour. So the market seems open.

Using in atmosphere crafts to compare a with a suborbital spacecraft? That doesn't sound like a good baseline. X-15 data probably would be the best for a baseline but I would think its still inadequate. Space Shuttle is a bad example for suborbital, since its an orbital craft (repeating myself?). Probably need a new testing craft to try different configurations and techniques.

Well yes a suborbital craft with stub wing would have a ballistic trajectory. And if its going to use max drag on reentry then it needs even more push on the launch to make its target.

I can see now that the launch on suborbital trip across the ocean would be close to orbital.

I can also see that the craft may be better off with regular length wings and not stub wings in order to glide further to make its target.


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Post Re: Suborital intercontinental travel   Posted on: Thu Sep 17, 2009 1:54 am
With a mother ship and spaceship configuration you can have different configurations.

You could possibly make the mother ship supersonic and launch the space ship at high speeds, for instance.

Or you could make the mother ship launch at a higher altitude that 50,000 feet, the altitude at which WhiteKnight launched SpaceShipOne.

You could possibly put an SRB on the spaceship. Or just make it plain bigger to accommodate a bigger rocket.

The great thing about it is that carbon composites are coming of age, so these and other things may be possible.

BTW WhiteKnight took about an hour to reach 500000 feet just to launch SpaceShipOne. So this suborbital idea wouldn't come close to the Concorde performance. But would overcome some of the Concorde's problems, like flying over land supersonically.

And using vertical rockets to do the job wouldn't work because regular rockets are so unreliable for scheduled commercial flights.


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Post Re: Suborital intercontinental travel   Posted on: Thu Sep 17, 2009 2:14 am
ralpher05 wrote:
SpaceShipOne pioneered a new way of reentry for manned spacecraft. Which needs less heat shield.

I think it needs less heat shield because it isn't moving very fast. If it were orbiting Earth in free-fall, it would need the same amount of heat shields to re-enter.


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Post Re: Suborital intercontinental travel   Posted on: Thu Sep 17, 2009 2:17 am
idiom wrote:
ralpher05 wrote:
80 or 90% of orbital? How do you figure this? And the 'super heated' atmosphere depends on the crafts velocity and/or deceleration. You really think its going to experience 2000 degrees fahrenheit on reentry?

The craft won't be going 17000 miles an hour, much less.


Then it won't be doing Atlantic crossings in 45 minutes.


New York City to London, England is only 3500 miles. If one were to travel at 5k mph, one could make the trip in less than 45 minutes. So, 1/3 of your proposed velocity would be sufficient.


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Post Re: Suborital intercontinental travel   Posted on: Thu Sep 17, 2009 2:22 am
ralpher05 wrote:
I can also see that the craft may be better off with regular length wings and not stub wings in order to glide further to make its target.

Wings make a lot of drag and are useless weight in space. That's why NASA researched lifting bodies back in the '60s.


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Post Re: Suborital intercontinental travel   Posted on: Thu Sep 17, 2009 3:42 am
Pooua wrote:
idiom wrote:
ralpher05 wrote:
80 or 90% of orbital? How do you figure this? And the 'super heated' atmosphere depends on the crafts velocity and/or deceleration. You really think its going to experience 2000 degrees fahrenheit on reentry?

The craft won't be going 17000 miles an hour, much less.


Then it won't be doing Atlantic crossings in 45 minutes.


New York City to London, England is only 3500 miles. If one were to travel at 5k mph, one could make the trip in less than 45 minutes. So, 1/3 of your proposed velocity would be sufficient.


The problem is trying to do 5000 mph or 8000km/h in atmosphere. The higher inital velocity is for the exo-atmospheric launch with a long glide.

The lower speed would need reboosting... so you end up with a hypersonic ramjet skipping along the top of the atmosphere which is the alternative.

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