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Russian Manned Space Vehicle May Land With Rockets
The Narrative Fallacy writes "Russia's next-generation manned space vehicle may be equipped with thrusters to perform a precision landing on its return to Earth. Previous manned missions have landed on Earth using a parachute or, in the case of space shuttles, a pair of wings. Combined with retractable landing legs and a re-usable thermal protection system, the new system promises to enable not only a safe return to Earth, but also the possibility of performing multiple space missions with the same crew capsule. The spacecraft will fire its engines at an altitude of just 600-800m, as the capsule is streaking toward Earth after re-entering the atmosphere at the end of its mission. After a vertical descent, the precision landing would be initiated at the altitude of 30m above the surface. Last July, Korolev-based RKK Energia released the first drawings of a multi-purpose transport ship, known as the Advanced Crew Transportation System (ACTS), which, at the time, Russia had hoped to develop in co-operation with Europe. 'It was explained to us how it was supposed to work and, I think, from the technical point of view, there is no doubt that this concept would work,' says Christian Bank, the leading designer of manned space systems at EADS-Astrium in Bremen, Germany. However, the design of the spacecraft's crew capsule had raised eyebrows in some quarters, as it lacked a parachute — instead sporting a cluster of 12 soft-landing rockets, burning solid propellant. Inside Russia, the idea apparently has many detractors. During the formal defense of the project, one high-ranking official skeptical of the rocket-cushioned approach to landing reportedly used an unprintable expletive to describe what was going to happen to crew members unlucky enough to encounter a rocket engine failure a few seconds before touchdown."
In most languages copulation isn't an expletive. A native German speaker told me that the worst he could think of was "Go to the Devil", in Deutch.
All ideas^H^H^H^H^Hprocesses in this post are Patent Pending. (as well as the process of patenting all postings)
In other words, they must think that adding that extra fuel weight (for landing) is worth the extra fuel weight that is needed to launch the rockets into space. After all, the landing fuel will cost them a lot of extra weight. I don't know how much extra it would be, but it doesn't sound like a good idea.
Full Tilt
Let's see, how fast might the ship being going when the landing system kicks in? Falling from orbit to the ground is going to produce a lot of velocity to bleed off in apparently a very short time. The shuttle uses both atmospheric braking and S-turns to bleed off velocity and still lands pretty darn fast.
It sounds like this just falls without a chute. I'm not going to do the math, but even if it is subsonic at 800m, you are going to have to brake like mad at the end. 10G braking? 20G doesn't sound like it would be outlandish. OK, so it is a short period of time and with solid-fuel rockets it is just one pulse. But it sounds like it would be ohe heck of a pulse.
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Ok, so the design is based upon rockets, but does it mean that it uses *no* aerodynamic braking at all? I don't know a whole lot about aerodynamics, but I remember from physics class the discussion of drag and terminal velocity. Is it possible that the shape of their vehicle has a relatively slow terminal velocity, so that the rockets don't have to do *that much* braking at the end? Not that I'm saying that I think even requiring a small amount of retro-rocket braking is a good design, but it seems like maybe you are assuming an awful lot about what speed it will be at when they fire the rockets?
It seems pretty inefficient to carry the fuel mass for the retro rocket braking all the way up out of the gravity well into orbit and then back down into the gravity well so you can use it in the last kilometer of the flight.
In other words, spend additional energy to take more energy up with you, which you will spend dissipating all of the energy you gained going up.
That, or to keep taking advantage of the viscous gas you'll find on the way down to brake, where available. If you want precision, then you add a bit of chemically-generated thrust to steer. Where there's not enough gas (Mars and smaller), gravity may be weak enough to make the DC-X approach add up.
This post contains no rudeness or derision of any kind. All arguments are friendly. Terms and exclusions may apply.
I don't know the first thing about rocket science, so let me ask the crowd here.
How do you synchronize the firing of 12 solid fueled rockets?
2174.749 f/s SOMEONE has the wrong terminal velocity. Are we sure this isn't a way to eliminate political dissidents?
I thought the Ruskie's where smarter than that, sounds like something nasa would propose. Russia has always had a successful space program
because they use well tested and simple engineering. Just a capsule it goes up and parachutes back to the ground, no wings no crazy rocket
assisted landing. The higher the component count and complexity the more room for failure.
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Thanks Srmalloy - learning about Russian "Mat" was the most interesting thing I read today while avoiding work.
With my newfound skill, I am sure you'll understand when I say 'Yob tvoyu mat' that it is in the spirit of friendship.