Musk to Mars

[CptRichardson]

I'm not sure why everyone thinks that a failure in Tesla or Solar City would impact SpaceX. The whole point of these things called 'corporations' is that such failures don't effect the other ones even if all of them are owned by the same entity. There's also the fact that SpaceX is generating a McDuckian silo of money that Musk can swim in thanks to actually being the best launch provider in the world at the moment and getting better all the time.

 

Furthermore, as I've said before, the pessimissm over SpaceX is getting really old. Yes, they've had delays, but generally barring superceding the need for something, they've actually delivered or are on track for delivering their technological promises with one exception (second stage landing). Heck, even their delays in the FH are because they keep managing to improve the F9 and have had to go back and adjust how they're building the FH several times to account for higher thrust in the component cores, not because it's actually too hard for them. That, and because they really haven't needed it yet, but will before too long when they get ahold of the alphabet soup agency contracts. There wasn't much point in having it earlier because other than those agencies there isn't anyone on the market at the moment who really NEED 50 tons to LEO (seriously, good god).  The same goes with their BFR. We know they've at least had their engines working for it for at least a year, and they've been busy designing the other hardware for the system for some time. Given how the FH has been delayed by improving the F9, it's not hard to see that the BFR has almost certainly been getting massively improved by advancements being taken from the F9, but is still approaching a completion state of design.

 

I mean, seriously, how many technological miracles does Musk have to pull out of his hat before you stop badmouthing him? The whole point of SpaceX is going space-core over mars, and  Musk has made sure that one way or another nobody can tell him no. Maybe not '2024', but they will get to Mars barring total nuclear war.

[Nibb31]

21 minutes ago, CptRichardson said:

There's also the fact that SpaceX is generating a McDuckian silo of money that Musk can swim in thanks to actually being the best launch provider in the world at the moment and getting better all the time.

Do you know something that we don't? SpaceX's finances are private and pretty confidential. We don't know if they are generating revenue or how much.

21 minutes ago, CptRichardson said:

Furthermore, as I've said before, the pessimissm over SpaceX is getting really old.

As I've said before, the starry-eyed cult following is getting old too.

I don't think it's pessimistic to believe that SpaceX lives and thrives in the same political and economical reality as the rest of the universe. Musk clearly has a reality distortion field when he talks about transforming into cyborgs, colonizing Mars, terraforming it with nukes, or sending people there in 2024. Pointing that out hardly counts as pessimism.

21 minutes ago, CptRichardson said:

I mean, seriously, how many technological miracles does Musk have to pull out of his hat before you stop badmouthing him?

Maybe when people stop using religious terminology, like "miracles" when referring to R&D programs.

 

[kerbiloid]

4 minutes ago, Nibb31 said:

Maybe when people stop using religious terminology, like "miracles"

Unplanned Rapid Events.

37 minutes ago, CptRichardson said:

I mean, seriously, how many technological miracles does Musk have to pull out of his hat before you stop badmouthing him?

Currently they have a 12-t single use launch vehicle and a cargo capsule. The same was in 1960s.

[benjee10]

1 hour ago, kerbiloid said:

Currently they have a 12-t single use launch vehicle and a cargo capsule. The same was in 1960s.

Sorry, I must have missed the part of the 1960s where rockets 20 stories tall flip around into a supersonic airstream and perform a pin-point landing on a barge in the middle of the Atlantic.

Musk isn't a miracle worker, but I would say he's befitting the term 'visionary' and, more importantly, he's a smart business man and knows how to motivate people (even if that can be in a sometimes... negative way). 14 years ago few people believed that a private company would be sending regular supply missions to the ISS. One year ago, I couldn't believe that SpaceX would be landing a booster back on dry land, especially after CRS-7. Three months ago, watching the launch coverage of CRS-8, I didn't expect to see an entire booster set itself down flawlessly on the deck of a rocking droneship. SpaceX will suffer delays, there will be setbacks, but ultimately I see no reason that they can't achieve their goals given their track record, and to suggest that they are anything other than innovative and pushing boundaries of space technology is frankly plain rude. 

[kerbiloid]

8 minutes ago, benjee10 said:

Sorry, I must have missed the part of the 1960s where rockets 20 stories tall flip around into a supersonic airstream and perform a pin-point landing on a barge in the middle of the Atlantic.

If this were the aim. Afaik, the aim was: reusable rocket, reusable pin-point landing ship (hard to say, why it needs that pin-point rather than a chute and a piece of desert).

For example: Gemini was tested with a delta-wing, but never used it. So, an interesting ability, but not a reusable Gemini as was planned.

Edited June 6, 2016 by kerbiloid

[linuxgurugamer]

1 minute ago, kerbiloid said:

If this were the aim. Afaik, the aim was: reusable rocket, reusable pin-point landing ship (hard to say, why it needs that pin-point rather than a chute and a piece of desert).

parachutes are heavy.  Desert is sandy.  Imagine sand in a rocket engine?  Also, in order to land in a desert, would require launching over land, something no one really wants to do

[kerbiloid]

6 minutes ago, linuxgurugamer said:

parachutes are heavy.

Heavier than 1.5-2 t of MMH/NTO, 8 engines and 4 landing legs?

And btw: and still an additional chute - as requires NASA.

6 minutes ago, linuxgurugamer said:

 Desert is sandy.  Imagine sand in a rocket engine?  Also, in order to land in a desert, would require launching over land, something no one really wants to do

Orion, CST-100, Soyuz, VA TKS are not hesitated with sand.
5 x 5 km accuracy (i.e. within KSC territory) is achievable with nowadays technics, so landing onto a bus stop is unlikely required.

Edited June 6, 2016 by kerbiloid

[benjee10]

Just now, kerbiloid said:

Heavier than 1.5-2 t of MMH/NTO, 8 engines and 4 landing legs?

Orion, CST-100, Soyuz, VA TKS are not hesitated with sand.

Strange as it may seem, yes, parachutes are heavier than landing gear. The 8 engines are going to be there parachute or not so that's irrelevant. The amount of propellant used in landing burn is very little considering that the rocket is almost entirely empty. Landing legs are designed to be as lightweight as possible. The parachutes required for a booster this size would be ridiculously huge and incredibly heavy; the shuttle SRB parachutes (which would be of a comparable size) mass around 3510kg; the mass of the landing legs of Falcon 9 is around 2000kg. 

As for CAPSULES landing in sand, they are CAPSULES not ROCKET BOOSTERS, so they land on a blunt heat shield. Rockets coming down in sand sounds like a terrible idea; if the terrain is not flat the sand will slide and they may tip or sink into it. Deserts also have the unfortunate habit of being in the complete middle of nowhere, which isn't a huge problem for a small space capsule which could conceivably be airlifted away by helicopter, but is rather a large inconvenience when dealing with a very large first stage. Plus, capsules are returning from an orbital flight so can choose their landing zone, whereas the booster must be recovered suborbital, which places it over the ocean, which would be even worse considering salt water corrodes rocket engines (cost of SRB refurbishment was higher than building new ones during the shuttle program because salt water corroded the casings). 

[linuxgurugamer]

11 minutes ago, kerbiloid said:

Orion, CST-100, Soyuz, VA TKS are not hesitated with sand.
5 x 5 km accuracy (i.e. within KSC territory) is achievable with nowadays technics, so landing onto a bus stop is unlikely required.

They land on sand, but aren't reusable.

[kerbiloid]

12 minutes ago, benjee10 said:

Strange as it may seem, yes, parachutes are heavier than landing gear. The 8 engines are going to be there parachute or not so that's irrelevant. The amount of propellant used in landing burn is very little considering that the rocket is almost entirely empty. Landing legs are designed to be as lightweight as possible. The parachutes required for a booster this size would be ridiculously huge and incredibly heavy; the shuttle SRB parachutes (which would be of a comparable size) mass around 3510kg; the mass of the landing legs of Falcon 9 is around 2000kg. 

23 t capsule under chutes.
http://www.space.com/21155-orion-parachute-test.html

Apollo (5 t capsule) chutes: Weight = 135 lb.
http://www.spaceaholic.com/index.php/Detail/Object/Show/object_id/26

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130011328.pdf

SpaceX Pad Abort Test: Dragon with chutes. And with engines+fuel+legs,

Btw... Didn't think about that before.
If it starts from the launchpad with its engines instead of LES, how would it land then without chutes?

 

Edited June 6, 2016 by kerbiloid

[fredinno]

cc

Edited June 6, 2016 by fredinno

[kerbiloid]

21 minutes ago, linuxgurugamer said:

They land on sand, but aren't reusable.

Orion, CST-100 afaik are reusable.

VA TKS exactly reusable (up to 10 times, IRL the same capsule was used 2 or 3 times. Edit: launched 3 times, but 1 of them - landed after launch abort).

Also one Gemini capsule was launched twice and successfully survived (yes, it lands on water).

 

Edited June 6, 2016 by kerbiloid

[benjee10]

4 minutes ago, kerbiloid said:

23 t capsule under chutes.
http://www.space.com/21155-orion-parachute-test.html

Apollo (5 t capsule) chutes: Weight = 135 lb.
http://www.spaceaholic.com/index.php/Detail/Object/Show/object_id/26

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130011328.pdf

SpaceX Pad Abort Test: Dragon with chutes. And with engines+fuel+legs,

Btw... Didn't think about that before.
If it starts from the launchpad with its engines instead of LES, how would it land then without chutes?

 

I was talking about the Falcon 9, not Dragon V2, but whatever.

The Dragon V2 engines are intended for use both for orbital manoeuvres and for landing, and abort in an emergency. Presumably when it aborts it uses the fuel allowed for orbital operations while preserving the fuel needed for landing. If not, the mass cost of parachutes is less for proportionally smaller payloads (i.e. a capsule rather than a booster) but SpaceX wants pin-point landings on a pad for ease and speed of recovery. It may not make a huge difference now, but in SpaceX's vision of a constant stream of launches and landings, the cost of sending a helicopter to recover a capsule from the desert/the ocean is eventually going to be a huge amount more than just driving it in a truck from the landing pad to the hangar. 

As for why it has both chutes and engines at the moment, currently the NASA contract requires them to land using chutes. It lands on legs anyway (which are extremely small) to protect the heat shield so that it can be reused. When/if Dragon V2 is used by SpaceX alone or by commercial non-NASA customers, it will land propulsively, as would the Red Dragon concept. I'm not clear on whether smaller emergency parachutes would still be included.

[kerbiloid]

16 minutes ago, benjee10 said:

The Dragon V2 engines are intended for use both for orbital manoeuvres and for landing, and abort in an emergency.

Dragon V2 weights, say, 12 t (without service module, quietly named "trunk" though it looks like a full-weight "service module" of Orion and CST-100).
For orbital operation it needs T/W ~ 0.5, i.e. 60 kN.
It carries 8x80 kN engines. Slightly overpowered,,, Unlikely it can fly more than 10 times. So, either 8 engines per 10 flights, or 1 single-use engine in a service module per every flight - no difference.
In any case, its engines are 10 times overpowered to be used on orbit.

Apollo CM mass = 5 t, its chutes (see link above) ~0.1 t.
So, Dragon chute weights ~ 0.25 t and looks absolutely good in that video. And in any case will be used (because of NASA).

LES mode. Max T/W of Dragon's engines is ~6, while all other known LESes give T/W 12-20. Slightly underpowered to be called LES (especially when the LV uses KeroLOX with wide range of explosive gas-air concentrations).
Also if Dragon has no chute, how will it land when its fuel is over running from the bursting rocket? As we can see, on chute.

I.e. it needs chutes in any case, but additionally carries up to orbit and then down to ground additional several tonnes of fuel/engines/legs.
If, say, all this stuff weights ~ 3-4 t, this means that every 1 of 3..4 Falcon launches will be lost to launch and return this useless things.
As Falcon probably can't be reused more than ~10 times too, this means that Dragon is a Falcon-killer.

Edited June 6, 2016 by kerbiloid

[benjee10]

4 minutes ago, kerbiloid said:

Dragon V2 weights, say, 12 t (without service module, quietly named "trunk" though it looks like a full-weight "service module" of Orion and CST-100).
For orbital operation it needs T/W ~ 0.5, i.e. 60 kN.
It carries 8x80 kN engines. Slightly overpowered,,, Unlikely it can fly more than 10 times. So, either 8 engines per 10 flights, or 1 single-use engine in a service module per every flight - no difference.
In any case, its engines are 10 times overpowered to be used on orbit.

Apollo CM mass = 5 t, its chutes (see link above) ~0.1 t.
So, Dragon chute weights ~ 0.25 t and looks absolutely good in that video. And in any case will be used (because of NASA).

LES mode. Max T/W of Dragon's engines is ~6, while all other known LESes give T/W 12-20. Slightly underpowered to be called LES (especially when the LV uses KeroLOX with wide range of explosive gas-air concentrations).
Also if Dragon has no chute, how will it land when its fuel is over running from the bursting rocket? As we can see, on chute.

I.e. it needs chutes in any case, but additionally carries up to orbit and then down to ground additional several tonnes of fuel/engines/legs.
If, say, all this stuff weights ~ 3-4 t, this means that every 1 of 3..4 Falcon launches will be lost to launch and return this useless things.
As Falcon probably can't be reused more than ~10 times too, this means that Dragon is a Falcon-killer.

It is a trunk not a service module because it is hollow for external cargo, just like current Dragon's hollow trunk. All OMS & life support are housed within the capsule, trunk just holds the solar cells which provide power as far as I'm aware. So, no it isn't quietly named trunk for any nefarious reason, it's named trunk because it's a trunk and not a service module. 

Only two of the engines are fired at any one time on orbit solving the TWR issue. 4 are used for landing. All 8 for abort. 

As I said in my previous post, I believe that reserve fuel is kept in abort scenarios for landing. I may be wrong and SpaceX may be planning on using chutes as backup for all flights but ideally will use propulsive landing for recovery cost savings. The point is that the Dragon would have the engines anyway since they are the OMS/abort engines, so why not use them for landings as well if they're capable of it? 

"Dragon is a Falcon-killer." How so? It's getting SpaceX some incredibly lucrative NASA crew transport contracts and will almost certainly be cheaper to operate than CST-100 given that that thing launches on the Atlas V, pretty much the most overpriced rocket currently in existence. And it will definitely be cheaper and have a much faster turnaround than Orion. Just because it carries things which may not be used in all scenarios it doesn't make it a 'useless thing' as you call it. Plus works as a multipurpose lander (Musk has stated that Dragon V2 will be capable of landing on every body in the solar system with only slight modifications) - makes sense to have a standardised lander design which can be produced in large quantities than designing a new lander every time. 

[kerbiloid]

18 minutes ago, benjee10 said:

It is a trunk not a service module because it is hollow for external cargo, just like current Dragon's hollow trunk

Why in launch abort test they start with this trunk? It is below the ship, it is dropped after engines stop. Why to lose T/W pulling up the useless weight?
Doesn't it also contain fuel required for orbital operations? Unlikely Dragon should land with just remains of inner fuel.
Where are solar panels if not on the "trunk"?
So, looks like it's a usual service module, just without engine.

18 minutes ago, benjee10 said:

Only two of the engines are fired at any one time on orbit solving the TWR issue. 4 are used for landing. All 8 for abort. 

Yes. I.e. only two of them indeed match their purpose (see above about abortion T/W and parachute mass).

18 minutes ago, benjee10 said:

I believe that reserve fuel is kept in abort scenarios for landing

Abort requires ~300 m/s, landing ~200 m/s. "Reserve" is enough good name for several tonnes which are lifted to orbit and back instead of several more tonnes of cargo.

18 minutes ago, benjee10 said:

"Dragon is a Falcon-killer." How so?

It weights 1.5-2 times more than really should without engine and immortal tanks,
So it requires 1.5-2 times more Falcon launches, spends Falcon lifespan 1.5-2 times faster than could.
Falcon already loses 20% of its cost per launch (due to single-use second stage) and 10-20% of cost more due to its own return and landing.
Add refurbishing procedures cost, damaged equipment replacement - and you get that reusable Falcon shall lose 100% of cost in ~3 flights.
As Dragon's dead weight - tanks and engines - drops this value 1.5-2 times more, this means that Falcon will hardly save more than one launch cost per its lifespan.

(Just btw: Space Shuttle Engines were reused ~8 times in average, 19 times max)

Edited June 6, 2016 by kerbiloid

[Nibb31]

23 minutes ago, kerbiloid said:

Why in launch abort test they start with this trunk? It is below the ship, it is dropped after engines stop. Why to lose T/W pulling up the useless weight?

The trunk has fins. Those fins are required to stabilize Dragon during the abort burn, like a shuttlecock. The trunk is jettisoned as soon as the burn is complete and the Dragon lands on parachutes.

That is launch abort mode.

Quote

Doesn't it also contain fuel required for orbital operations? Unlikely Dragon should land with just remains of inner fuel.

No. The trunk only carries solar panels and radiator panels, no fuel.

Quote

Where are solar panels if not on the "trunk"?
So, looks like it's a usual service module, just without engine.

A service module is typically a propulsion stage. You can call it a service module if you want, but it's really just a fairing for unpressurized cargo and a support structure for the solar panels and radiators.

Quote

Abort requires ~300 m/s, landing ~200 m/s. "Reserve" is enough good name for several tonnes which are lifted to orbit and back instead of several more tonnes of cargo.

The Dragon capsule carries enough dV for either abort or landing, not both.

Edited June 6, 2016 by Nibb31

[benjee10]

26 minutes ago, kerbiloid said:

Why in launch abort test they start with this trunk? It is below the ship, it is dropped after engines stop. Why to lose T/W pulling up the useless weight?
Doesn't it also contain fuel required for orbital operations? Unlikely Dragon should land with just remains of inner fuel.
Where are solar panels if not on the "trunk"?
So, looks like it's a usual service module, just without engine.

The trunk provides some aerodynamic stability during abort, apparently. If you actually read my post instead of picking and choosing little parts of it you would see that I did indeed say that that's where the solar panels are. The solar panels, however, are extremely light since they are a fixed, wraparound design and therefore lack the heavy unfurling mechanisms of the solar panel designs. The trunk is otherwise PURELY FOR UNPRESSURISED CARGO. It does not contain any fuel, just like the current Dragon v1. Here is a view of the Dragon V1 trunk:

Most recently it was used to carry the BEAM to the ISS. As you can see, minus cargo, it looks pretty empty. It's basically a fairing. You can also see in this pic how in the final Dragon V2 it will have little fins to aid with aerodynamics (I'm assuming that the aero is not so much of a concern in a mocked-up pad abort since the vehicle is not already supersonic, hence the simple mass-mockup of the trunk in the abort test):

So, let's break it down shall we:

What service modules contain usually:

• Life support systems
• Fuel for main engine
• Power generation systems
• RCS
• Main engine

What the Dragon V2 trunk contains:

• Power generation system
• Empty space for cargo

26 minutes ago, kerbiloid said:

Yes. I.e. only two of them indeed match their purpose (see above about abortion T/W and parachute mass).

Abort requires ~300 m/s, landing ~200 m/s. "Reserve" is enough good name for several tonnes which are lifted to orbit and back instead of several more tonnes of cargo.

Those several tonnes would be lifted to orbit regardless if they were built into the capsule or not. An orbital spacecraft requires fuel tanks and engines. Whether they're on the capsule or on a service module they will still be lifted into orbit. The same propellant is being used for abort as would be used for OMS and/or landing (depending on whether reserve is kept or parachute is used) so ultimately there is no unnecessary mass here.

26 minutes ago, kerbiloid said:

It weights 1.5-2 times more than really should without engine and immortal tanks,
So it requires 1.5-2 times more Falcon launches, spends Falcon lifespan 1.5-2 times faster than could.
Falcon already loses 20% of its cost per launch (due to single-use second stage) and 10-20% of cost more due to its own return and landing.
Add refurbishing procedures cost, damaged equipment replacement - and you get that reusable Falcon shall lose 100% of cost in ~3 flights.
As Dragon's dead weight - tanks and engines - drops this value 1.5-2 times more, this means that Falcon will hardly save more than one launch cost per its lifespan.

Except we don't know refurbishment costs, we don't know savings on reflying a booster instead of launching new, plus SpaceX isn't throwing away any engines, fuel tanks or life support systems for each capsule like CST-100 and Orion will do. That's a pretty hefty cost saving. 

PLUS, from what I can find, it weighs less than CST-100 does! 6,400kg dry + 1,688kg propellant = 8,088kg total for Dragon V2 instead of 13,000kg for CST-100! You whole argument that it weight double what it should is pretty much entirely irrelevant since the other way of doing pretty much exactly the same thing (minus external payload capability, minus pin-point landings, minus recovery of all significant non-structural elements except the solar cells) weighs more! Even if it costs Falcon 9 some reusability (which I'm not entirely convinced of), it is still far more efficient than it's nearest rival, and launches on a rocket which is far less expensive. I'm not getting all the doom and gloom vibes you seem to be getting here.

 

EDIT: Was ninja'd by @Nibb31, drat it

Edited June 6, 2016 by benjee10

[kerbiloid]

2 minutes ago, Nibb31 said:

just a fairing for unpressurized cargo and a support structure for the solar panels and radiators.

PAO of Soyuz is the same, just with engine.

2 minutes ago, Nibb31 said:

No. The trunk only carries solar panels and radiator panels, no fuel.

Then they are (should be) carrying up and down barrels inside the capsule, inside its heat protected hull, increasing its inner volume and the hull mass - rather than just jettison empty cans as they do with more capacious tanks of the 2nd stage,

6 minutes ago, Nibb31 said:

The Dragon capsule carries enough dV for either abort or landing, not both.

Then how will it land without parachute after abortion?
If it anyway carries parachute (not too heavy thing - just ~0.2-0.3 t) and is not destroyed using it, why carry 6 engines more and a cystern of fuel inside the capsule?

4 minutes ago, benjee10 said:

Those several tonnes would be lifted to orbit regardless if they were built into the capsule or not.

~1-2 tonnes less would be lifted if use chute (or 1-2 additional tonnes of cargo) - and see above about hull mass due to increased volume.
If count this increased hull mass, even worse: 3-4 tonnes of the rocket payload are just spent.

 

9 minutes ago, benjee10 said:

it weighs less than CST-100 does! 6,400kg dry + 1,688kg propellant = 8,088kg total for Dragon V2 instead of 13,000kg for CST-100!

Miracles happen. One 6-crew spaceship with 1.7 t of fuel and 8 engines weights less than another one- without them.
Sure, parachutes of CST-100 are made of iron and weight 5 tonnes;
CST-100 is counted in total (with service module and LES), while Dragon - empty hull?
Dragon parameters should be... er... adjusted, as they are still not published.

[Nibb31]

6 minutes ago, kerbiloid said:

PAO of Soyuz is the same, just with engine.

PAO ?

Soyuz abort is different because the whole stack architecture is different. However, yes, Soyuz carries its fairing with grid fins for stabilization during an abort, which is similar, but it leaves the service module behind.

Quote

Then they are (should be) carrying up and down barrels inside the capsule, inside its heat protected hull, increasing its inner volume and the hull mass - rather than just jettison empty cans as they do with more capacious tanks of the 2nd stage,

Then how will it land without parachute after abortion?

It carries a backup parachute for abort and as a backup if the SuperDracos fail on descent.

Quote

If it anyway carries parachute (not too heavy thing - just ~0.2-0.3 t) and is not destroyed using it, why carry 6 engines more and a cystern of fuel inside the capsule?

Because parachutes are hard to reuse.

 

Edited June 6, 2016 by Nibb31

[kerbiloid]

2 minutes ago, Nibb31 said:

Because parachutes are hard to reuse.

Who on Earth needs to reuse piece of nylon?..

3 minutes ago, Nibb31 said:

PAO

What is called "service module" in English wiki, but would cause a terms confusion here (as question is: can an unpressurized structure with tanks, batteries and solar panels be called "service module").

[benjee10]

3 minutes ago, kerbiloid said:

PAO of Soyuz is the same, just with engine.

So... completely different then, considering the PAO contains fuel tanks and manoeuvring engines, and Dragon trunk does not? 

4 minutes ago, kerbiloid said:

Then they are (should be) carrying up and down barrels inside the capsule, inside its heat protected hull, increasing its inner volume and the hull mass - rather than just jettison empty cans as they do with more capacious tanks of the 2nd stage,

I'm not sure what you're trying to say here. Dragon trunk is not just going to be empty, it will hold cargo. My point is that it isn't a service module as you suggest. All the service module functions are housed in the crew module. 

5 minutes ago, kerbiloid said:

If it anyway carries parachute (not too heavy thing - just ~0.2-0.3 t) and is not destroyed using it, why carry 6 engines more and a cystern of fuel inside the capsule?

Reusability, precision of landing, comfort (soft landing with rocket jets will result in a lower impact speed than with the parachute; still survivable under parachutes, but not ideal if you have delicate samples or just don't want to cause discomfort for your astronauts)

10 minutes ago, kerbiloid said:

~1-2 tonnes less would be lifted if use chute (or 1-2 additional tonnes of cargo) - and see above about hull mass due to increased volume.
If count this increased hull mass, even worse: 3-4 tonnes of the rocket payload are just spent.

But Falcon CAN lift that amount, and the Dragon can perform operationally as it is with this design. If it were lighter you would be wasting Falcon 9 payload capability. 

11 minutes ago, kerbiloid said:

Miracles happen. One 6-crew spaceship with 1.7 t of fuel and 8 engines weights less than another one- without them.
Sure, parachutes of CST-100 are made of iron and weight 5 tonnes;
CST-100 is counted in total (with service module and LES), while Dragon - empty hull?
Dragon parameters should be... er... adjusted, as they are still not published.

CST-100 is counted in total and Dragon is counted in total I believe. Dragon is lighter. Perhaps with cargo they would come to similar levels; either way, the mass difference is either going to be in Dragon's favour or pretty much negligible. 

2 minutes ago, kerbiloid said:

Who on Earth needs to reuse piece of nylon?..

That's a very (deliberately) naive statement. Spacecraft parachutes need to be extremely large and are made out of advanced, expensive materials to withstand high temperatures and air speeds. Then you have deployment systems (which are explosive and therefore have to be replaced every time) as well as accounting for all the quality control and testing that has to go into producing such a vast amount of fabric. 

4 minutes ago, kerbiloid said:

What is called "service module" in English wiki, but would cause a terms confusion here (as question is: can an unpressurized structure with tanks, batteries and solar panels be called "service module").

By my understanding a service module would need to also provide propulsion and store fuel. Whereas the Dragon trunk contains no fuel tanks and is otherwise purely structural aside from allowing an attachment point for solar cells. It has already been established here that it is not a service module, and ultimately the terminology used for it is irrelevant since your assumptions about it have already been proved wrong.

I don't understand your pessimism towards Dragon - nothing about it strikes me as particularly unbelievable. It's funny how the more successful SpaceX is, the more nitpicky and obscure the criticisms levelled against it are. The challenge of designing an economical crew capsule seems orders of magnitude smaller than the challenge of designing a soft landing first stage booster and then getting it within a couple of meters of its target on a barge, and yet they've accomplished that. What's so hard to believe?

[Bill Phil]

Musk isn't a miracle worker. All he's doing is using his fame to show off cool ideas that other people had. Still good that they're gettng attention, but Musk is just a famous rich guy that shows the ideas off.

Electric cars are ancient tech. Good ones were available in the 30s, and they were also sold earlier in the early 1900s. Invented in the late-ish 1800s. 

The Falcon 9 is hardly innovative. It's just "doing" what people have thought of and did studies on since the 50s. The only innovative thing is its accomplishments.

Edited June 6, 2016 by Bill Phil

[kerbiloid]

14 minutes ago, benjee10 said:

I'm not sure what you're trying to say here

Usually  empty cans are to be dropped in space rather than kept inside the capsule, increasing the pressurized and heat-protected volume.
Saving, say, 100 kg of a tank, they add, say, 200 kg of the ship hull.
I hoped that I was wrong and they just drop the tanks with... trunk.

This looks like buy a diesel truck instead of a light pickup to return empty plastic bottles.

14 minutes ago, benjee10 said:

Reusability

Just put a new parachute. It's exactly not more expensive than a single use trunk and second stage.

14 minutes ago, benjee10 said:

precision of landing

5x5 km for nowadays parachute landing from orbit.
In any case they use toxic hyperholic fuel and probably need to wait for the rescue team.

14 minutes ago, benjee10 said:

comfort (soft landing with rocket jets will result in a lower impact speed than with the parachute

The less acceleration - the more fuel to be spent (and launched). Two seconds of discomfort vs several tonnes of payload.
Btw, 1500 of toxic and flammable hyperholic propellant just near the cabin look not like an additional comfort factor.

14 minutes ago, benjee10 said:

CST-100 is counted in total and Dragon is counted in total I believe.

If CST-100 counted with cargo and service module (i.e. launch mass), why Dragon is empty and without trunk?

14 minutes ago, benjee10 said:

Spacecraft parachutes need to be extremely large and are made out of advanced, expensive materials to withstand high temperatures and air speeds. Then you have deployment systems (which are explosive and therefore have to be replaced every time) as well as accounting for all the quality control and testing that has to go into producing such a vast amount of fabric. 

Chutes weight 100-200 kg (as you can read above), and yet nobody have told they cost too much that 8 engines will be cheaper.
 

Edited June 6, 2016 by kerbiloid

[Emperor of the Titan Squid]

this has nothing to do with the mars mission really. i personally believe that the first mars landing will be done by an IMRS like mission, with international colaboration, and commercial construction of parts.