Friday, December 23, 2011

Marines On The Scene In 90 Minutes

Or your a$$-whuppin' is free!

It's the Ithacus SSTO, delivering 1,200 United States Marines with all the trimmings anywhere on the planet in an hour and a half.

Man, build those and you don't need nearly so many overseas bases. So of course, we didn't. Bummer.

8 comments:

docjim505 said...

Also useful for getting Matt Dodson, Tex Jarman, and all their fellows to class on time.

Nathan said...

Semper Fi, Space Marines!

Dave H said...

One downside that comes to mind is one SAM could wipe out the whole battalion. Vertical landing craft have to slow down to land, making them easy targets. I don't know if the Ithacus had any sort of touch-and-go capability, but I'd sure as heck want to be able to abort a landing quick if the landing zone got hot.

azmountaintroll said...

So how do you get it back to base after the mission? Or is it a one shot deal, like the gliders of WWII?

Anonymous said...

Sorry to be a wet blanket, but there are a couple of major problems with this concept.

First: SSTO stands for Single Stage To Orbit, and "Orbit" means circularized. That means you launch it, and it stays up. At best, this concept is a semi-ballistic, ala Robert Heinlein's Semi-Ballistic transports in his book "Friday". They are launched in a ballistic trajectory - they go up, and then they come down.

Second: The rocket has drop tanks. At best, that makes it a 1.5 stage rocket, not single stage. If you include the solid rocket boosters which it also has, it becomes more of a 2.5 stage rocket.

So it's not an SSTO. It's not single stage, and it doesn't go into orbit.

We are a long way from being able to do a real SSTO rocket. Even if you use technology 20 years in the future from today, any SSTO design you could come up with would still wind up with a minus 20 percent payload. Minus 20 percent payload means you don't stay in orbit, you re-enter.

This concept went nowhere for several very important reasons.

First, by the very nature of it's flight profile, which is ballistic, this vehicle is constrained to follow a Great Circle Route. Put one end of a string on your launch site on a globe, and stretch the string straight to your landing site, and you have the Great Circle Route for that particular flight or mission. With very little experimentaion involving a globe and a piece of string, you will quickly find that it is difficult at best to come up with a Great Circle Route which does not overfly a hostile power. Not a good thing.

Second, it is difficult if not impossible to distinguish between a ballistic troop transport and a ballistic nuclear missile. It's pretty big ask to expect a hostile power to believe you when you say that the ballistic vehicle you just launched in their direction is indeed just a troop transport that is only going to fly over their country, and not a first-strike ballistic missile that will drop itself or a bunch of MIRVs on their country.

Third, as DaveH said, it is vulnerable at the LZ. First, a rocket this size will be spectacularly visible for an extended period of time. Remember, it's re-entering from orbit. There will be no element of surprise. Everyone will see it coming. Second, it will also take a significant amount of time to get slowed down, and while it is doing so, it will be vulnerable to ANYthing. A SAM missile will not be necessary to bring it down. A simple RPG fired at it while it's 500 feet up would do the job nicely. At 500 feet, it will be going so slowly it will be a sitting duck, and nobody will suvive a 500 foot fall. Third, It's a rocket. Shooting at rockets is guaranteed to produce exciting results, none of which would be of the life-extending sort for the occupants.

And sorry, Dave - there's no aborting one of these. It will use every last ounce of propellant just to get safely back on the ground. Once.

Don't get me wrong. I love the concept. But it could only work as a civvie transport in a situation equivalent to near world peace, where there is universal trust and an expectation of peacable intentions, neither of which I see happening in my lifetime.

BoxStockRacer

Roberta X said...

BSR: I take exception to "We are a long way from being able to do a real SSTO rocket." Jeff Bezos (Blue Origin) is treating as much nearer to happening; even SpaceX is working one up.

Asa for terminology, I called it what they called it. I though flight time was a bit long and wondered if flight profile called for something other than a simple ballistic.

OTOH, possibly it was intended for after SHTF, or during, at which point there'd be more to worry about than one missile-ful of Marines.

--I have a problem with ballistic transport, the civvy version: I seriously don't want the landing field anywhere near where I live. One little oops would leave too big a hole in the ground. Is a superquick hop to an hour outside Tokyo worth driving halfway to Chicago? Maybe.

J.R.Shirley said...

Don't know how combat-capable they'd be after re-entry, though.

Also, what Dave said..I also had some of the objections of BoxStockRacer, especially with regards to terminology. I mean, Whoah~ cool!

John

Anonymous said...

Roberta:

Flight time may seem a bit long compared to the time for a complete orbit in space, but you have to spend a measurable percentage of time at the beginning of the flight accelerating through atmosphere, and a nearly equal amount of time at the end of the flight decelerating in atmosphere. At both ends, you're pretty much limited to three Gs or less because you have people on board. Given a slow start, lower than orbital delta-V at apogee, and a slow stop, 90 minutes is probably somewhere in the ballpark for getting halfway around the planet.

Back before the Cold War ended, I designed launch vehicles, upper stages, satellites, spacecraft, re-entry vehicles, aerobrakes, etc. for a living. All this stuff you see people attempting to do now has been tried before by people who had hard schedules to meet, which is why most of it didn't get past the concept stage. They couldn't deliver. One of the more enlightening things that happened to me circa 1984 was when I told my Dad about one of the projects a co-worker was working on. Dad had worked on nearly every space program right through the end of the Apollo program. His response: "Oh yea - we tried that back in 1968. Here's what happened to us . . ." Sure enough, after an extended study, and lots of hair-pulling, my co-worker's project team wound up reaching the exact same conclusion that My Dad's generation had come to over 15 years earlier, but without the benefit of even knowing that the study had already been done.

Turns out that because the aerospace industry goes through these massive layoff purges, lessons learned by one generation of aerospace engineers are completely lost and not passed on to the next generation, so everything must be learned all over again.

I applaud Blue Origin and SpaceX for at least making the effort, but if they are going to succeed, SSTOs won't be a part of getting to a circularized orbit. They didn't work for my Dad's generation, they didn't work for mine, and both My Dad and I had access to MUCH better engine technology than the current generation, who, sadly, are left to salvage engines left over from programs long dead.

I've watched multiple space startups come and go, and every time one fails, it seems one of two questions wasn't asked. (A) "Did they even bother to order up the study results from the Government Printing Office from the last time this was tried", or (B) "Are the investors being taken for a ride (again) by a crusader who refuses to use a calculator and the Rocket Equation."

The answer to (A) is: They don't even know the work has already been done because nobody is left to tell them about it.

The answer to (B)? If you don't know it has already been tried, and you don't know how to do it yourself, you are at the mercy of the pitchman who thinks he's smarter than all those who came before (or just wants to spend your money).

BoxStockRacer