[jr2]

Ummm.. I read that somewheres.  You sure it can't break the sound barrier by the time the tail clears the tower?  It should only exert about 5-7 Gs, IIRC.  How fast would it be going if it did 5Gs all the way up?

[Herra Tohtori]

Here's a space shuttle exceeding Mach 1 on ascent.

No service tower visible.

Anyway, the acceleration of the space shuttle is not constant during ascent, and it's limited to ~3 g's (approximately 30 m/s^2) at it's peak. Immediately after the lift-off the acceleration is significantly less because there's so much fuel onboard - and when most of the fuel is consumed and the mass reduces, the engines need to be throttled down to keep the acceleration limited to the nominal 3 g's.

Another throttle-down event (down to about two thirds throttle) is when the shuttle passes the point of maximum dynamic pressure, which is starts at the time when the shuttle passes the Mach 1 velocity about 50 seconds after lift-off and lasts some while after because the air travels at different velocities in different locations around the shuttle so the shockwaves don't all appear and end simultaneously. After clearing that point and getting fully supersonic, the engines are throttled up again.

Here's an interesting article about the shuttle lift-off experience told by an astronaut. It's worth reading, excellently written and informative text IMHO:

At T-6 seconds, we hear the roar of the three main engines starting up far below us.

Because the engines are off-centre, the entire vehicle rocks forward and then back to vertical over the next 6 seconds. During these critical moments, the shuttle's computers check readings from the engines to ensure that they are working correctly before issuing the command to ignite the two solid-fuel booster rockets. Once the boosters are lit, they cannot be turned off, so you want to be absolutely sure that you don't leave the ground with anything working less than 100 per cent. You certainly want to be sure you are pointed straight up!

Suddenly we feel a huge kick in the pants, or more precisely, a sudden thump on our backs as the boosters ignite. Looking out the window, we see the ground falling away. The noise and vibration are overpowering. One astronaut described the feeling as "driving down a railroad track in a car with no shock absorbers". There is not much we can do to control our flight at this point. I find myself thinking, "I hope it all holds together!" We can feel the shuttle rotate in a roll manoeuvre as soon as we clear the launch tower, to point towards our desired orbit.

About 45 seconds after lift-off, still climbing almost vertically, we break the sound barrier and the aerodynamic pressure on the vehicle reaches a maximum - "max Q". In order to minimise the stress on the vehicle, our engines throttle down to 65 per cent, and the acceleration decreases slightly, but the vibration gets much stronger as sonic shock waves play all over the outside of the vehicle. It is hard to believe that we can shake harder than at lift-off, but we do, so much so that during my first flight I wondered if the wings were going to fall off. I reassured myself that 15 shuttle flights had already survived lift-off with their wings intact.

Max Q is over about a minute after lift-off, the engines return to full power and we feel a surge of acceleration. At this point, the shuttle is travelling more horizontally than vertically and is flying inverted, but the sensation of forward acceleration dominates that of gravity, so I never had the feeling of being suspended upside down.

As our fuel gets used up, our mass decreases and the acceleration increases to around 2.5 g (2.5 times normal gravity). We are all waiting for the boosters to finish their job, and it is a good feeling just before 2 minutes into the flight to feel the acceleration taper off as the solid fuel is exhausted and then hear a boom as explosive bolts fire to release the boosters. The boosters fire small rockets to ensure they move clear of the shuttle, and for several seconds the cockpit is engulfed in flame, which is particularly spectacular if the launch is at night.

...damn, I so would want to get a ride to orbit at some point of my life. Although I think I would prefer a Sojuz to a space shuttle... Soviet space tech FTW!

[spartan_0214]

Yeah, so good it got cancelled 


http://en.wikipedia.org/wiki/Buran_program

After the first flight, the project was suspended due to lack of funds and the political situation in the Soviet Union. The two subsequent orbiters, which were due in 1990 (informally Ptichka, meaning "little bird") and 1992 (Shuttle 2.01) were never completed. The project was officially terminated on June 30, 1993 by President Boris Yeltsin. At the time of its cancellation, 20 billion roubles had been spent on the Buran program.[4]

The program was designed to boost national pride, carry out research, and meet technological objectives similar to those of the U.S. shuttle program, including resupply of the Mir space station, which was launched in 1986 and remained in service until 2001. When Mir was finally visited by a space shuttle, the visitor was a U.S. shuttle, not Buran.

The Buran SO, a docking module that was to be used for rendezvous with the Mir space station, was refitted for use with the U.S. Space Shuttles during the Shuttle-Mir missions.

[Herra Tohtori]

Hey! Firefly and Farscape were cancelled too even though they were awesome.

Besides, Buran was only cancelled because the Soviet bureaucracy and general way of managing things at the end decade of the Cold War was so inefficient that the funds demanded by the project were multiplied to the extent that it actually contributed to the final collapse of the USSR economy and subsequent (counter-)revolution, after which the space programme was the least of everyone's worries for a good long while... Buran itself was actually in many ways superior to the US Orbiter, but at any rate, that's not what I was referring to.

I meant the legendary Sojuz (or Soyuz, transliteration varies) spacecraft Propelled by Sojuz Launch Vehicle, which is about the most reliable booster rocket in terms of successful launch ratio as well as number of successful launches (having over 1700 launches on it's books). Designed by equally legendary Sergey Korolyev in the sixties, when they still made space ships with the good old schematics - a big rocket with a thermos bottle (with some systems thrown in) on top. A shame that Korolyev happened to die, which arguably actually caused the Soviet Union to fall behind on the race to the Moon...

You have to admit that there is much more oomph in rocketing out to the sky on top of a gigantic rocket in a small capsule instead of moderately sized and relatively inefficient space aeroplane.

I mean, just look at it! It looks like a missile, which is rather awesome considering it's payload is people.



And look at it's cockpit! Anything that has a cockpit like this can't be bad. It looks like it came from Emmett Brown's workshop, but since it works I wouldn't care... who needs avionics anyway!



There are some pretty cool clips on YouTube about Soyuz launches. The launch pad is designed with Monty Python's "something completely different" in mind when compared to US equivalent launch facilities, like those used with Apollo missions.

However, since the US has finally seen the light and went back to true and tried formula of a space capsule (named Orion, incidentally) and a booster rocket system (named Ares), I would definitely accept a ride in that as well, at least if they get that ball running before the end of civilization as we know it.


But talking about Soviet space tech... Did you know that some of the Salyut space stations were actually armed with a 23mm or 30mm Nudelmann aircraft cannon called "self-defence gun" and they tested it successfully "with positive results at ranges from 500 m to 3000 m", destroying a target satellite in the process?

[spartan_0214]

Hey! Firefly and Farscape were cancelled too even though they were awesome.

Farscape not so much. Bad actors and bad props.

(The rest...)

Meh, probably true, but have you counted how many Soviet subs are at the bottom of the Ocean? you can't because they can't

[Herra Tohtori]

The space shuttle would soon be at the bottom of the ocean too if it was put there!

(Or: I can point out irrelevant facts too. )

Russian subs would be good too if they were built for one use as accurately as the Soyuz vehicles. Or, if they had been properly maintained.

Conversely, Soyuz vehicles would probably suck as bad as Russian navy ships if they were re-usable and thus would demand continuous maintenance after missions, and if the space programme was as extensive as the Russian army/navy... Actually, you kinda have pointed out already what would happen to a re-usable Soviet Spacecraft, the only one that ever went to space and back was left into a deteriorating hangar which wventually collapsed on top of the ship and rendered it impossible to repair.

That's the good thing about booster engines. You need a good reliable design, and you need to test it a lot and develope it further all the time, but you only need to build and launch the rocket once. There's no need for maintenance between launches and that takes one variable out of the fuzzy equation that determines the probability of successful launch. Theoretically, every booster engine is as reliable as another, while a re-usable ship will age despite all the maintenance and inspection; it's impossible to prevent the airframe from aging, even with all the duct tape in the world.

Same with all the systems in a space shuttle. It has a lot more things that can go wrong than a booster engine and a capsule. Not to mention that most failures with a Soyuz would be possible to recover from with no loss of crew, whereas in the shuttle it's safe landing or bust... well, at least until the orbital re-entry parachutes become standard issue.

But I have to agree on the part that Farscape wasn't as good as Firefly, not even close. And it kinda got boring after the first season when all the initial crossing-the-wall-between-worlds-rage was gone, to the extent that I didn't bother to even watch all the seasons I aquired after halfway through season two or so.

[spartan_0214]

(Or: I can point out irrelevant facts too. )

Sorry, thought the subject was Soviet Technology... hard to keep up with the segues at HLP...

[WMCoolmon]

Ummm.. I read that somewheres.  You sure it can't break the sound barrier by the time the tail clears the tower?  It should only exert about 5-7 Gs, IIRC.  How fast would it be going if it did 5Gs all the way up?

The speed of sound is about 343 m/s, and the shuttle is about 60 meters long. If it were going at the speed of sound by the time its tail cleared the launch tower, it would be moving at least five-six times its length every second after that.

If it did 5Gs, it'd be going roughly 1/3 the speed of sound. (Again, this is assuming constant acceleration)

[karajorma]

However, since the US has finally seen the light and went back to true and tried formula of a space capsule (named Orion, incidentally) and a booster rocket system (named Ares), I would definitely accept a ride in that as well, at least if they get that ball running before the end of civilization as we know it.

Incidentally I seem to recall that the Americans are now using rockets based on the old Russian moon rocket design for their own launches. I think Lockheed-Martin are the ones doing it IIRC. 

[Herra Tohtori]

Yes, and if I recall correctly, Lockheed also bought some technology solutions for the F-35 at least partially from Yakolev/Russians, who had built a supersonic (on paper) VTOL-aircraft sometime in 1960's, with thrust vectoring main nozzle, hovering fans and other stuff, but it never went to production, and apparently the prototype was not able to go supersonic. Tha name of the plane was Yakolev Yak-141.

The plane is still kinda cool, it looks like it defies gravity on low-speed turns, as you can see from this clip.


...although, the Russian moon rocket was kinda grande fiasco, mainly because the aforementioned Sergey Korolyev was dead and didn't have part in designing it, IMHO. N1 moon rocket was incredibly untested and underfunded and thus incredibly unreliable, all launch attempts ended in more or less catastrophic failures.

What's wrong with using Saturn V designs as basis? Just modernize the engines, make a new airframe with new materials and you got perhaps the coolest looking spaceship with improved payload capacity on your hands.

...well, I took a look at Wikipedia and on the Rocketdyne article it says they've designed a new version of J-2 engine used in upper stages of Saturn V, so on that part I suppose they've taken the right path there.

They do need to make the rockets black and white, though. Otherwise, I'd say that the rockets themselves look a lot cooler than the Space Shuttle... but the coolest of these is the first one.

[karajorma]

...although, the Russian moon rocket was kinda grande fiasco, mainly because the aforementioned Sergey Korolyev was dead and didn't have part in designing it, IMHO. N1 moon rocket was incredibly untested and underfunded and thus incredibly unreliable, all launch attempts ended in more or less catastrophic failures.

From what I remember of a program about it the Russians probably would have made it in a couple more years but once the Americans got there first they simply scrapped the plans and said that they weren't interested in trying to get there.