SpaceX Boaster Reuse and Capsule Powered Landings- Really as good as it sounds?

[ZooNamedGames]

I have been thinking- SpaceX has been leading the world into a new age of rocketry. They have unveiled their Dragon V2 (manned) spacecraft. Which, with it's counterpart- the SpaceX Falcon 9 reuseable boaster will be reused by landing on a specific site after the launch. Either a barge or on land.

However I have a question about SpaceX's capsule... as it stands to be along side Boeing's space capsule as the manned transport vehicle to LEO. SX plans on having it's capsule land via ENGINES and no parachutes on its return.

I personally find this (although a "cool" idea) a all together BAD idea. It is risky- and it costs more per capsule... and capsules CAN be reused using the old parachute landing method. To give a new perspective- this new SX capsule with be the ONLY manned spacecraft to return to Earth and NOT use a parachute. As the Mercury capsules used them- so did Gemini, Apollo, AND the Space Shuttles after making contact with the runway (granted a drogue chute and not used like the others- it still was used). The Russians even used them for the Soyuz (The Vostok spacecraft did not use them but at the same time the pilot ditched the spacecraft before landing using personal parachutes).

A normal spacecraft has several advantages over SX's most recent design:

Parachutes- guaranteed to work, as long as they deploy, and if they don't you pack reserves.

More reliability- To date (as far as I'm aware of) we have lost 0 pilots to post-re-entry (i.e. After the re-entry effects have diminished)... leaving the classic capsule style as the best option.

Just as accurate- If SX's boast is that it can make a specific landing site, then it's wrong! As capsules can land in specific places as well! As long as it's in the capsules orbital path. Sure it has more control over landing but then you run into issues...

Issues with SX's design:

More parts to fail- with more systems and MORE engines to fire- you increase the possible failure rate and likely hood and with the engines being your ONLY hope of landing failure of ONE rocket could cause you to have off-center thrust which can cause MANY issues.

Uses the MAX LES setup- Instead of the well known tower escape device (commonly known as LES/LAS (Launch Escape/Abort System)), SX will use a dome device which fires multiple engines to have the same effect of launching it up and away from the launch vehicle... however using that setup is (again) more to fail. As your firing multiple engines rather than one in a common LES/LAS setup.

More expinsive per use- The SX setup will cost far more per use and construction per capsule than any other (potentially including the new Orion capsule)

Benefits of the SX design:

Reuseable- Being able to be recovered at a specific landing site and less parts lost on landing.

So am the only one who feels this? Or am I mistaken on this and not seeing something ingenius that makes this worth while?

[JedTech]

Because this:

[Kryten]

NASA wants parachute landings, and they're the only existing customer for Dragon. Propulsive is off the table until somebody wants it.

[Dkmdlb]

Parachutes- guaranteed to work, as long as they deploy, and if they don't you pack reserves.

The Dragon capsule also has spare parachutes.

More reliability- To date (as far as I'm aware of) we have lost 0 pilots to post-re-entry (i.e. After the re-entry effects have diminished)... leaving the classic capsule style as the best option.

See above.

Just as accurate- If SX's boast is that it can make a specific landing site, then it's wrong! As capsules can land in specific places as well! As long as it's in the capsules orbital path. Sure it has more control over landing but then you run into issues...

They aren't just as accurate. SpaceX wants to land the capsule like right on a landing pad at the launch complex. That's the whole point.

More parts to fail- with more systems and MORE engines to fire- you increase the possible failure rate and likely hood and with the engines being your ONLY hope of landing failure of ONE rocket could cause you to have off-center thrust which can cause MANY issues.

Yes, more parts to fail, but there is always backup chutes. And one engine won't cause off-center thrust because there are redundant engines. An engine failure can easily be compensated for.

Uses the MAX LES setup- Instead of the well known tower escape device (commonly known as LES/LAS (Launch Escape/Abort System)), SX will use a dome device which fires multiple engines to have the same effect of launching it up and away from the launch vehicle... however using that setup is (again) more to fail. As your firing multiple engines rather than one in a common LES/LAS setup.

If one engine fails in a launch tower the crew is killed. If one engine fails in the dragon capsule the crew is saved.

More expinsive per use- The SX setup will cost far more per use and construction per capsule than any other (potentially including the new Orion capsule)

You have a source for that? Because it seems extremely unlikely.

[Frozen_Heart]

As the Mercury capsules used them- so did Gemini, Apollo, AND the Space Shuttles after making contact with the runway (granted a drogue chute and not used like the others- it still was used). The Russians even used them for the Soyuz (The Vostok spacecraft did not use them but at the same time the pilot ditched the spacecraft before landing using personal parachutes).

First - "We've always done it that way" isn't a good argument for anything. True it means that method is tried and proven, but it also means that other ideas are often ignored even if they work just as well.

Parachutes- guaranteed to work, as long as they deploy, and if they don't you pack reserves.

More reliability- To date (as far as I'm aware of) we have lost 0 pilots to post-re-entry (i.e. After the re-entry effects have diminished)... leaving the classic capsule style as the best option.

The Dragon V2 uses 8 engines, 2 in each pod. Even if an engine fails (unlikely) the landing can continue with several engines out. If too many are lost for landing then they have chutes as a backup.

Just as accurate- If SX's boast is that it can make a specific landing site, then it's wrong! As capsules can land in specific places as well! As long as it's in the capsules orbital path. Sure it has more control over landing but then you run into issues...

Chutes are not accurate. They pretty much have to land on water due to only being able to hit a target miles across. And salt water wrecks everything it gets into contact with making reuse uneconomical due to everything needing complete refurbishment like the shuttle boosters. The Russians can land on the land due to Kazakhstan having hundred of miles of flat plains with nothing to hit. Even so the landing is rough.

Propulsive landing can in theory hit a helicopter landing pad.

More parts to fail- with more systems and MORE engines to fire- you increase the possible failure rate and likely hood and with the engines being your ONLY hope of landing failure of ONE rocket could cause you to have off-center thrust which can cause MANY issues.

Uses the MAX LES setup- Instead of the well known tower escape device (commonly known as LES/LAS (Launch Escape/Abort System)), SX will use a dome device which fires multiple engines to have the same effect of launching it up and away from the launch vehicle... however using that setup is (again) more to fail. As your firing multiple engines rather than one in a common LES/LAS setup.

See the redundant rockets answer.

More expinsive per use- The SX setup will cost far more per use and construction per capsule than any other (potentially including the new Orion capsule)

I've not actually looked at the costs for the Spacecraft. Is this speculation or are the costs per unit listed somewhere?

[AngelLestat]

Also you can use the dragon engines as escape pod (very important)... that is what spacex will test in five days.

If you dont have that, then you need a solid booster tower. And it will not provide the same safe margin.

Also you can use the onboard engines to correct any other problem with the launch, orbit, etc. If you run out of fuel, you still have the parachutes..

You can not guide parachutes, and its terminal speed is still very high, so you need to land on water or install solid rockets or air bags.. If you land on water, then you have a problem with reusability.

Parachutes should remain in the past. There are much better ways to get a soft landing.

[Superluminaut]

The dragon is safer than conventional abort systems because it allows you to abort at any time.

[Whirligig Girl]

NASA wants parachute landings, and they're the only existing customer for Dragon. Propulsive is off the table until somebody wants it.

Propulsive is meant for SpaceX to reuse its own capsules at their own launch pad when such a thing is made, if I'm not mistaken.

[tater]

It is also then a backup for chutes, for the ASA requirement. Chute ever fails… they can land propulsively. Options are always good.

[Motokid600]

How much time and money does an escape tower cost? All for it to not be used and get trashed partway through a launch.

Having the Dragons engines act as both its main propulsion AND escape motors? That's absolutely brilliant. No need for a wasteful tower.

My concern however is the last seconds of that propulsive landing. What if one pair of Dracos on one side of the craft shutdown?

Like in that gif above if a pair failed then and there.... What then? Can the opposite pair of engines shutdown and the remaining throttle harder before catastrophe?

How does the Dragon2 gimbal? Throttle regulations?

Edited May 1, 2015 by Motokid600

[Frozen_Heart]

Like in that gif above if a pair failed then and there.... What then? Can the opposite pair of engines shutdown and the remaining throttle harder before catastrophe?

From what I've heard I think its 4 engines that are needed to land the Dragon. So in theory it only needs 2 pods active to land. It would switch off the opposite pair and then activate the other unused engine in each of the other pods.

[Kibble]

For parachute landings, the unused fuel needed for a potential abort probably equals the mass of a standard LAS system. Only with more performance hit, because you don't drop it partway into the flight. Personally I always liked the solid escape tower idea - like the standard capsule shape it was one of those first ideas that just stuck because it works so well. It looks "right"!

[Kryten]

Propulsive is meant for SpaceX to reuse its own capsules at their own launch pad when such a thing is made, if I'm not mistaken.

For who? As far as we can tell they haven't sold any tourist tickets or made real progress with commercial space stations, NASA is the only game in town.

[Frozen_Heart]

the unused fuel needed for a potential abort probably equals the mass of a standard LAS system. Only with more performance hit, because you don't drop it partway into the flight

Well if they don't have to abort then the fuel is used for landings and so isn't wasted mass. If they do have to abort then the parachute is used instead.

More expinsive per use- The SX setup will cost far more per use and construction per capsule than any other (potentially including the new Orion capsule)

Looking up further details on the 3 commercial crew proposals shows that Dragon is the cheapest per flight, not the most expensive.

For who? As far as we can tell they haven't sold any tourist tickets or made real progress with commercial space stations, NASA is the only game in town.

Pretty sure that there will be further manned spaceflight past the commercial crew contracts. And I'm pretty sure SpaceX will be competing for it.

Edited May 2, 2015 by Frozen_Heart

[Armchair Rocket Scientist]

For parachute landings, the unused fuel needed for a potential abort probably equals the mass of a standard LAS system. Only with more performance hit, because you don't drop it partway into the flight. Personally I always liked the solid escape tower idea - like the standard capsule shape it was one of those first ideas that just stuck because it works so well. It looks "right"!

If I'm not mistaken the SuperDracos use the same fuel that would be used for orbital manuevering on a nominal mission (which naturally isn't going to be used if you abort).

[mrfox]

Parachutes- guaranteed to work, as long as they deploy, and if they don't you pack reserves.

More reliability- To date (as far as I'm aware of) we have lost 0 pilots to post-re-entry (i.e. After the re-entry effects have diminished)... leaving the classic capsule style as the best option.

Cosmonaut Vladimir Komarov died on Soyuz1 due to chute deployment failure.

After 18 orbits, Soyuz 1 fired its retrorockets and reentered the Earth's atmosphere. Despite the technical difficulties up to that point, Komarov might still have landed safely. To slow the descent, first the drogue parachute was deployed, followed by the main parachute. However, due to a defect, the main parachute did not unfold; the exact reason for the main parachute malfunction is disputed.[6] [7]

Komarov then activated the manually deployed reserve chute, but it became tangled with the drogue chute, which did not release as intended. As a result, the Soyuz reentry module fell to Earth in Orenburg Oblast almost entirely unimpeded, at about 40 m/s (140 km/h; 89 mph). A rescue helicopter spotted the descent module lying on its side with the parachute spread across the ground. The retrorockets then started firing which concerned the rescuers since they were supposed to activate a few moments prior to touchdown. By the time they landed and approached, the descent module was in flames with black smoke filling the air and streams of molten metal dripping from the exterior. The entire base of the capsule had burned through and by this point, it was obvious that Komarov had not survived, but there was no code signal for a cosmonaut's death, so the rescuers fired a signal flare calling for medical assistance. Another group of rescuers in an aircraft then arrived and attempted to extinguish the blazing spacecraft with portable fire extinguishers. This proved insufficient and they instead began using shovels to throw dirt onto it. The descent module then completely disintegrated, leaving only a pile of debris topped by the entry hatch. When the fire at last ended, the rescuers were able to dig through the rubble to find Komarov's remains strapped into the center couch. Doctors pronounced the cause of death to be from multiple blunt-force injuries.

http://en.wikipedia.org/wiki/Soyuz_1

Edited May 2, 2015 by mrfox