I'm pretty sure SpaceX put ULA out of business (To some degree)

[Rune]

1 hour ago, AngelLestat said:

Not sure, but I never knew why restart engines was so complicate before..  In fact, they already found ways to use LOX-LCH4 for RSC using laser ignition. This will be great because you would not need extra tanks with poison fuels with low ISP for RSC. This also helps to use the amount of fuel as you most need in main thrust or RSC.

The russkies also managed kerolox RCS thrusters on Buran, but it was a bit more than a big headache to make them, very complicated stuff. See, restarting a rocket engine is difficult in space for a number of reasons: first, the liquids don't have a "down" to fall to, so they tend to form a blob and float in the middle of your tank. Then if you solve that (baffles, RCS settling thrust, or a small solid kick to settle the propellants like the S-IVb), you have the problem of starting the turbopumps spinning to create pressure on the combustion chamber. Remember that those things spin at thousands of RPM's and thus have big inertias, and they are normally powered by the combustion products of a reaction that happens that happens later in the cycle! The traditional solution to start turbopumps, BTW, is to run a small amount of hypergolic propellants through it with external hydraulic power, making them go 'boom' when they meet on their own and kick-starting the thermodynamic cycle of the engine to get fuel pressure into the combustion chamber, and power to keep the turbopump accelerating towards operating RPMs. That's why I asked about hypergolics.

That is the main reason interplanetary space probes all run on monopropellant or hypergolic rockets, BTW. In those, being pressure-fed, you only have valves to move around to restart: move a couple of valves, the propellant tanks pressurize, move a couple other valves, and the fluids meet on the combustion chamber, igniting on their own (or decomposing on the catalytic bed in the case of monopropellants).

So running a complicated engine like a Merlin is space is very different from firing a pressure-fed RCS system, basically.

 

Rune. I could still learn a lot on the subject, BTW, so bring on the responses!

[saabstory88]

4 hours ago, Rune said:

Ah, ok, I see what you mean now. You are completely factually wrong then, BTW. The F9's second stage can take the coast and relight to make the full GSO insertion, as the one on v1.2 was tested to do so in the very last flight. It made the news, even, right at the end of some of the more in-depth articles. And Centaur is not a "high thrust" stage, it is a high Isp stage, which means it has less thrust if anything. It also has heavy insulation, and leaks fuel as it makes the climb to GSO, like any deep cryogenic tank, and of course has a relatively awful mass ratio compared with soft cryogens like LOX, or storables that can get crazy tankage mass ratios.

No need to, the Merlin has a great capability to restart multiple times, and they should get little to no boiloff. If the battery and comms hold, the stage can keep on firing.

It would be really interesting to compare the two stages, BTW, after a really long coast, like a lunar insertion. If the battery was enough and they don't lose too much pressurant, Falcon's upper stage (which really needs a name, IMO) could be relit to insert around the moon... BTW, anybody knows the Merlin's restart method? It's amazing how many times they relight the booster's central engine on a nominal mission (3), and right now I can't remember how they get the turbopump spinning... AFAIK they have no hydrazine on the booster, right?

 

Rune. The russkies have been inserting on GSO from an inclined transfer orbit for decades, and never once used cryogenic fuels to do so.

SpaceX does not offer GSO insertions. The relight test was for GTO, not for GSO, which is why the stage was re-lit after 20 minutes, not after 6 hours. Take a look at the actual documentation from SpaceX: http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf 

Page 14, table 3-1. It is not an omission that GSO is not listed in these tables, it's just not a service that the Falcon family offers. Table 3-2 lists their orbital insertion accuracy, and as you can see, GSO insertion is not listed there either. I'm inclined to believe the manufacturer that they know exactly what their vehicles are designed to do.

Here is some math to explain why they don't offer GSO capabilities: 

Initial 185km x 185km parking orbit: 7,797 m/s

Insertion to GTO: 2,460 m/s

Falcon 9 v1.1-FT Maximum Theoretical Delta V (No Payload): 11,125 m/s

Falcon 9 v1.1-FT Boost phase staging velocity (RTLS): 1,527 m/s  - Demonstrated with F9-21 (orbcomm)

Residual Delta V after parking orbit, and GTO transfer burn (no payload): 2,395 m/s - So the stage itself can insert to GTO with no payload, but

Residual Delta V after parking orbit, and GTO transfer burn (Minimum payload rating, per users guide, any smaller payloads need ballast to bring it up to this level): 1,189 m/s - This is not enough for GSO, which requires at minimum, 1,500 m/s more

 

Falcon 9 v1.1-FT Boost phase staging velocity (ASDS): 2,220 m/s - 8000 km/h, quoted from Elon in post flight conference call

Residual Delta V after parking orbit, and GTO transfer burn (no payload): 3,087 m/s - So the stage itself can insert to GTO with no payload, but again

Residual Delta V after parking orbit, and GTO transfer burn (Minimum payload rating, any smaller payloads need ballast to bring it up to this level): 1,882 m/s - So we can hit GSO with the minimum payload assuming perfect performance, and no boil off. 

 

So while it looks promising, the other factor is that SpaceX's payloads are mostly Geostationary, not Geosynchronous, which requires a 1,800 m/s burn, not a 1,500 m/s burn. Not to mention, that most popular sat busses are much heavier, in the range of 4,000-5,500kg per sat. If we run these calculations with a 4,750kg sat, to be in the middle of that payload range of the business that SpaceX really wants, we only get a residual delta v of 587 m/s.

 

So what of the Falcon Heavy? Doesn't it's increased lift mean we can do GSO missions with that booster? Not really. The limiting factor here is not lift, but SpaceX's dedication to re-usability. The top quoted staging velocity that they can expect recovery from has been quoted as 3,430 m/s (mach 10). So using our same average payload of 4,750kg we get a residual of 1,797 m/s. So a Falcon heavy might possibly be able to do a GSO insertion, assuming SpaceX is willing to risk making a customer specific modification to the second stage for the extended coast time, which may soil their second stage track record. If we look at something more sensible, like a 10,500kg double satellite stack to GTO on the heavy, which would put it in competition with the Ariane 5, we get a residual of 258 m/s on the Falcon Heavy. It's almost like that's exactly what it's designed to do! (Which it is...)

 

SpaceX says the Falcon series won't do GSO missions, math says that the Falcon series won't do GSO missions. SpaceX knows they can pick up the GTO market, with a much more simple vehicle, and leave GSO market to the ULA. The kind of staging velocities which you can achieve on the Altas V are much more conducive to this, especially when paired with the Centaur, because they don't want to reuse it.

[saabstory88]

A couple other notes:

The Merlin series of engines use TEA/TEB for all engine ignitions. Ullage is accomplished on the upper stage using thrusters. 

The Proton (K or M) is a 4 stage vehicle, which allows a lot of flexibility for it's orbital maneuvers. The Blok-D massed a little over 17,000kg, so with a satellite on top, the entire stack mass was within the Protons LEO capacity. The Briz-M does a little bit of the final LEO insertion before the GTO burn, because the stacks usually mass around 25,000kg, which is a little above even the upgraded Proton LEO capacity. The Briz-M also has a drop tank which further increases its total delta-v.

The breakdown of ULA masses to GTO and GSO are available here (NOTE! Imperial Units!): http://i.imgur.com/IIrDQWZ.jpg

[wumpus]

Other things killed off by a successful Falcon landing: stupid SSTO proposals (I hope).

Arguing for SSTO tends to confuse cause and effect.  "Magic" ISP leads to SSTO*.  Trying to do so with existing chemical reactions leads to madness.  While the empty booster SpaceX landed might not have weighed more than the payload (my back-of-envelope gets them within an order of magnitude), this would require at least doubling the fuel needed in the second stage to get it to orbit, which requires again doubling the fuel (and thrust) needed in the first stage - without increasing the dry mass at all (and that's assuming some pretty generous calculations.  I'd also like to see what the SpaceX engineers would have to say about cutting the dry mass of their rocket in half).

Or you could just recover the first stage and be done with it.  Which is still likely easier than recovering the whole thing from orbit.  

* yes, all air breathers can be assumed to have "magic" ISP.  But even the Sabre people don't really explain why it is so much better to use the (presumably) expensive SABRE engine (instead of a normal rocket engine) for going from mach 6 to orbital velocity (and haul that whole air cooler along to orbit as well).  The supremacy of the staged rocket hasn't changed a lot since Goddard's time, and air breathing stages are extremely hard to get anywhere near half the delta-v needed for orbit.

[fredinno]

2 hours ago, Rune said:

The russkies also managed kerolox RCS thrusters on Buran, but it was a bit more than a big headache to make them, very complicated stuff. See, restarting a rocket engine is difficult in space for a number of reasons: first, the liquids don't have a "down" to fall to, so they tend to form a blob and float in the middle of your tank. Then if you solve that (baffles, RCS settling thrust, or a small solid kick to settle the propellants like the S-IVb), you have the problem of starting the turbopumps spinning to create pressure on the combustion chamber. Remember that those things spin at thousands of RPM's and thus have big inertias, and they are normally powered by the combustion products of a reaction that happens that happens later in the cycle! The traditional solution to start turbopumps, BTW, is to run a small amount of hypergolic propellants through it with external hydraulic power, making them go 'boom' when they meet on their own and kick-starting the thermodynamic cycle of the engine to get fuel pressure into the combustion chamber, and power to keep the turbopump accelerating towards operating RPMs. That's why I asked about hypergolics.

That is the main reason interplanetary space probes all run on monopropellant or hypergolic rockets, BTW. In those, being pressure-fed, you only have valves to move around to restart: move a couple of valves, the propellant tanks pressurize, move a couple other valves, and the fluids meet on the combustion chamber, igniting on their own (or decomposing on the catalytic bed in the case of monopropellants).

So running a complicated engine like a Merlin is space is very different from firing a pressure-fed RCS system, basically.

 

Rune. I could still learn a lot on the subject, BTW, so bring on the responses!

Why not just use cold gas LOX/RP1 by making the RCS thrusters like small release valves instead?

[fredinno]

12 minutes ago, wumpus said:

Other things killed off by a successful Falcon landing: stupid SSTO proposals (I hope).

Arguing for SSTO tends to confuse cause and effect.  "Magic" ISP leads to SSTO*.  Trying to do so with existing chemical reactions leads to madness.  While the empty booster SpaceX landed might not have weighed more than the payload (my back-of-envelope gets them within an order of magnitude), this would require at least doubling the fuel needed in the second stage to get it to orbit, which requires again doubling the fuel (and thrust) needed in the first stage - without increasing the dry mass at all (and that's assuming some pretty generous calculations.  I'd also like to see what the SpaceX engineers would have to say about cutting the dry mass of their rocket in half).

Or you could just recover the first stage and be done with it.  Which is still likely easier than recovering the whole thing from orbit.  

* yes, all air breathers can be assumed to have "magic" ISP.  But even the Sabre people don't really explain why it is so much better to use the (presumably) expensive SABRE engine (instead of a normal rocket engine) for going from mach 6 to orbital velocity (and haul that whole air cooler along to orbit as well).  The supremacy of the staged rocket hasn't changed a lot since Goddard's time, and air breathing stages are extremely hard to get anywhere near half the delta-v needed for orbit.

SSTOs can work- you would just need something the size of the Shuttle External Tank + 6 SSMEs to launch something like a 20 T payload. If you get reusability done well, SSTO can actually save operating costs, since you can skip the VAB with an SSTO (except for payload and fairing integration).

7 hours ago, Rune said:

Ah, ok, I see what you mean now. You are completely factually wrong then, BTW. The F9's second stage can take the coast and relight to make the full GSO insertion, as the one on v1.2 was tested to do so in the very last flight. It made the news, even, right at the end of some of the more in-depth articles. And Centaur is not a "high thrust" stage, it is a high Isp stage, which means it has less thrust if anything. It also has heavy insulation, and leaks fuel as it makes the climb to GSO, like any deep cryogenic tank, and of course has a relatively awful mass ratio compared with soft cryogens like LOX, or storables that can get crazy tankage mass ratios.

No need to, the Merlin has a great capability to restart multiple times, and they should get little to no boiloff. If the battery and comms hold, the stage can keep on firing.

It would be really interesting to compare the two stages, BTW, after a really long coast, like a lunar insertion. If the battery was enough and they don't lose too much pressurant, Falcon's upper stage (which really needs a name, IMO) could be relit to insert around the moon... BTW, anybody knows the Merlin's restart method? It's amazing how many times they relight the booster's central engine on a nominal mission (3), and right now I can't remember how they get the turbopump spinning... AFAIK they have no hydrazine on the booster, right?

 

Rune. The russkies have been inserting on GSO from an inclined transfer orbit for decades, and never once used cryogenic fuels to do so.

What I meant was that a 3rd stage could increase the Delta-V to high-energy trajectories to allow for direct to GEO missions, or at least GSO missions.

[saabstory88]

3 hours ago, fredinno said:

SSTOs can work- you would just need something the size of the Shuttle External Tank + 6 SSMEs to launch something like a 20 T payload. If you get reusability done well, SSTO can actually save operating costs, since you can skip the VAB with an SSTO (except for payload and fairing integration).

What I meant was that a 3rd stage could increase the Delta-V to high-energy trajectories to allow for direct to GEO missions, or at least GSO missions.

Interesting point about an SSME based SSTO, however, for the price of a single engine, you can buy a whole Falcon 9 flight.

[Workable Goblin]

11 hours ago, Rune said:

That is the main reason interplanetary space probes all run on monopropellant or hypergolic rockets, BTW. In those, being pressure-fed, you only have valves to move around to restart: move a couple of valves, the propellant tanks pressurize, move a couple other valves, and the fluids meet on the combustion chamber, igniting on their own (or decomposing on the catalytic bed in the case of monopropellants).

So running a complicated engine like a Merlin is space is very different from firing a pressure-fed RCS system, basically.

 

Rune. I could still learn a lot on the subject, BTW, so bring on the responses!

Although reliability is a reason, the main reason is probably that it's much easier to store hypergolics than most other things in space; you do have to keep them heated, but you don't have to worry about boil off, unlike most other propellant combinations. This is really important when your destination is 10+ years away from launch...

[gliese-aerospace]

On December 27, 2015 at 1:41 PM, Spaceception said:

You heard of the Falcon 9 launch on December 21st, right? Mind blowing, Game changer, The launch that krakened off/wowed pretty much every rocket company on the planet, yeah, you know what I'm talking about

Holy hyperbole Batman...

[Rune]

On 1/1/2016 at 5:17 PM, saabstory88 said:

SpaceX does not offer GSO insertions. The relight test was for GTO, not for GSO, which is why the stage was re-lit after 20 minutes, not after 6 hours. Take a look at the actual documentation from SpaceX: http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf 

Page 14, table 3-1. It is not an omission that GSO is not listed in these tables, it's just not a service that the Falcon family offers. Table 3-2 lists their orbital insertion accuracy, and as you can see, GSO insertion is not listed there either. I'm inclined to believe the manufacturer that they know exactly what their vehicles are designed to do.

Here is some math to explain why they don't offer GSO capabilities: 

Initial 185km x 185km parking orbit: 7,797 m/s

Insertion to GTO: 2,460 m/s

Falcon 9 v1.1-FT Maximum Theoretical Delta V (No Payload): 11,125 m/s

Falcon 9 v1.1-FT Boost phase staging velocity (RTLS): 1,527 m/s  - Demonstrated with F9-21 (orbcomm)

Residual Delta V after parking orbit, and GTO transfer burn (no payload): 2,395 m/s - So the stage itself can insert to GTO with no payload, but

Residual Delta V after parking orbit, and GTO transfer burn (Minimum payload rating, per users guide, any smaller payloads need ballast to bring it up to this level): 1,189 m/s - This is not enough for GSO, which requires at minimum, 1,500 m/s more

 

Falcon 9 v1.1-FT Boost phase staging velocity (ASDS): 2,220 m/s - 8000 km/h, quoted from Elon in post flight conference call

Residual Delta V after parking orbit, and GTO transfer burn (no payload): 3,087 m/s - So the stage itself can insert to GTO with no payload, but again

Residual Delta V after parking orbit, and GTO transfer burn (Minimum payload rating, any smaller payloads need ballast to bring it up to this level): 1,882 m/s - So we can hit GSO with the minimum payload assuming perfect performance, and no boil off. 

 

So while it looks promising, the other factor is that SpaceX's payloads are mostly Geostationary, not Geosynchronous, which requires a 1,800 m/s burn, not a 1,500 m/s burn. Not to mention, that most popular sat busses are much heavier, in the range of 4,000-5,500kg per sat. If we run these calculations with a 4,750kg sat, to be in the middle of that payload range of the business that SpaceX really wants, we only get a residual delta v of 587 m/s.

 

So what of the Falcon Heavy? Doesn't it's increased lift mean we can do GSO missions with that booster? Not really. The limiting factor here is not lift, but SpaceX's dedication to re-usability. The top quoted staging velocity that they can expect recovery from has been quoted as 3,430 m/s (mach 10). So using our same average payload of 4,750kg we get a residual of 1,797 m/s. So a Falcon heavy might possibly be able to do a GSO insertion, assuming SpaceX is willing to risk making a customer specific modification to the second stage for the extended coast time, which may soil their second stage track record. If we look at something more sensible, like a 10,500kg double satellite stack to GTO on the heavy, which would put it in competition with the Ariane 5, we get a residual of 258 m/s on the Falcon Heavy. It's almost like that's exactly what it's designed to do! (Which it is...)

 

SpaceX says the Falcon series won't do GSO missions, math says that the Falcon series won't do GSO missions. SpaceX knows they can pick up the GTO market, with a much more simple vehicle, and leave GSO market to the ULA. The kind of staging velocities which you can achieve on the Altas V are much more conducive to this, especially when paired with the Centaur, because they don't want to reuse it.

Well, I stand corrected then, SpaceX definitely doesn't market full GSO insertions on the Falcon 9. Makes sense, since that's what Heavy is for, IMO. I don't really think they will mind throwing out a center core every now and then (F9H could be the place where "old cores go to die") and staging it at high velocity with a heavy upper stage, but the standard ~5mT commsat. After all, Musk has commented a couple of time on the Heavy's throw capability to Mars (Red Dragon). Also, nothing is stopping them from building a fourth Draco-powered circularization stage, if the market demands it, or they want to really irk ULA. So, to say the stage can't do it... with a light enough payload, and using the first stage in an expendable fashion, I would be very surprised if it couldn't, considering Merlin's throttle range and the 9 engines on the first stage. Kerolox stages weather long waits much better than H2/LOX ones... in every sense, their engineering requirements are lower.

On 1/1/2016 at 7:11 PM, fredinno said:

SSTOs can work- you would just need something the size of the Shuttle External Tank + 6 SSMEs to launch something like a 20 T payload. If you get reusability done well, SSTO can actually save operating costs, since you can skip the VAB with an SSTO (except for payload and fairing integration).

What I meant was that a 3rd stage could increase the Delta-V to high-energy trajectories to allow for direct to GEO missions, or at least GSO missions.

As I said, up there, yeah, I guess they could, and they would even have the classically perfect engine for that in the Draco and SuperDraco family. But... honestly, I don't see it, you have to create another line with complicated to handle propellants... I have a hard-to-shake distrust of hypergolics.

 

Rune. Also, thanks for the TEA/TEB comment, gave me the answer I was looking for (it does use a limited number of hypergolic ignitions after all).

Edited January 3, 2016 by Rune

[fredinno]

44 minutes ago, Rune said:

Well, I stand corrected then, SpaceX definitely doesn't market full GSO insertions on the Falcon 9. Makes sense, since that's what Heavy is for, IMO. I don't really think they will mind throwing out a center core every now and then (F9H could be the place where "old cores go to die") and staging it at high velocity with a heavy upper stage, but the standard ~5mT commsat. After all, Musk has commented a couple of time on the Heavy's throw capability to Mars (Red Dragon). Also, nothing is stopping them from building a fourth Draco-powered circularization stage, if the market demands it, or they want to really irk ULA. So, to say the stage can't do it... with a light enough payload, and using the first stage in an expendable fashion, I would be very surprised if it couldn't, considering Merlin's throttle range and the 9 engines on the first stage. Kerolox stages weather long waits much better than H2/LOX ones... in every sense, their engineering requirements are lower.

As I said, up there, yeah, I guess they could, and they would even have the classically perfect engine for that in the Draco and SuperDraco family. But... honestly, I don't see it, you have to create another line with complicated to handle propellants... I have a hard-to-shake distrust of hypergolics.

 

Rune. Also, thanks for the TEA/TEB comment, gave me the answer I was looking for (it does use a limited number of hypergolic ignitions after all).

Well, I was going to originally plan for a Kerstrel-derived version, but Kerstrels are no longer in production, for Dracos are the only thing a third stage CAN work with right now.

[saabstory88]

1 hour ago, Rune said:

Well, I stand corrected then, SpaceX definitely doesn't market full GSO insertions on the Falcon 9. Makes sense, since that's what Heavy is for, IMO. I don't really think they will mind throwing out a center core every now and then (F9H could be the place where "old cores go to die") and staging it at high velocity with a heavy upper stage, but the standard ~5mT commsat. After all, Musk has commented a couple of time on the Heavy's throw capability to Mars (Red Dragon). Also, nothing is stopping them from building a fourth Draco-powered circularization stage, if the market demands it, or they want to really irk ULA. So, to say the stage can't do it... with a light enough payload, and using the first stage in an expendable fashion, I would be very surprised if it couldn't, considering Merlin's throttle range and the 9 engines on the first stage. Kerolox stages weather long waits much better than H2/LOX ones... in every sense, their engineering requirements are lower.

As I said, up there, yeah, I guess they could, and they would even have the classically perfect engine for that in the Draco and SuperDraco family. But... honestly, I don't see it, you have to create another line with complicated to handle propellants... I have a hard-to-shake distrust of hypergolics.

 

Rune. Also, thanks for the TEA/TEB comment, gave me the answer I was looking for (it does use a limited number of hypergolic ignitions after all).

I wouldn't be suprised if we see a SuperDraco powered third stage similar to Fregat, that's a really good point. I think that sort of thing is much more likely than SpaceX going backwards towards expendable flight, and is sort of low threshold/high profitability.

[davidy12]

Given the fact that Falcon Heavy is coming, and the Vulcan can lift less than half the payload, I agree. I KNOW that payload doesn't matter, but in terms of usefulness in the future (IE: Moon bases, manned Habitats, etc) it does make sense.

Also, @saabstory88, Delta V? You mean Delta IV right? Or is there some new Delta rocket I've never heard of?

Edited January 3, 2016 by davidy12

[saabstory88]

5 minutes ago, davidy12 said:

Given the fact that Falcon Heavy is coming, and the Vulcan can lift less than half the payload, I agree. I KNOW that payload doesn't matter, but in terms of usefulness in the future (IE: Moon bases, manned Habitats, etc) it does make sense.

Also, @saabstory88, Delta V? You mean Delta IV right? Or is there some new Delta rocket I've never heard of?

Delta V = change in velocity

That is, unless you are referencing a Typo I made several posts back and haven't noticed.

 

Also, the limiting factor on the Falcon Heavy is the Maximum Payload System Weight rating. As it stands, they have only rated the Falcon Heavy for its max payload in the RTLS/ASDS mode. It's not as simple as saying "Hey, we're going to throw this one away, let's max it out!". They will likely have to go through another process of certifying the upper stage for anything more than about 25,000kg, which is the max payload they need for DoD missions. The payload weight of dual comm-sat stacks vs a Red Dragon to mars is similar, so they don't need to be able to throw anything more than their customers need. When / If something as specialized as a fully fledged Bigelow module comes around, they contract will be lucrative enough that extra certification / integration is a given.

[davidy12]

10 minutes ago, saabstory88 said:

Delta V = change in velocity

That is, unless you are referencing a Typo I made several posts back and haven't noticed.

Sorry, I didn't notice that. I know what Delta V is.

[fredinno]

On 12/31/2015 at 1:55 PM, ColKlonk said:

17 minutes ago, davidy12 said:

Given the fact that Falcon Heavy is coming, and the Vulcan can lift less than half the payload, I agree. I KNOW that payload doesn't matter, but in terms of usefulness in the future (IE: Moon bases, manned Habitats, etc) it does make sense.

Also, @saabstory88, Delta V? You mean Delta IV right? Or is there some new Delta rocket I've never heard of?

 

Delta-V is a very important tool showing how far you can go in KSP and IRL.

 

On a serious note, though, it's actually referring to a hypothetical Delta IV successor. It would be funny if it existed- "We need more Delta V!!!"

[sojourner]

"The only way we'll get more Delta V is to build a Delta V!"

[Rune]

36 minutes ago, saabstory88 said:

Delta V = change in velocity

That is, unless you are referencing a Typo I made several posts back and haven't noticed.

 

Also, the limiting factor on the Falcon Heavy is the Maximum Payload System Weight rating. As it stands, they have only rated the Falcon Heavy for its max payload in the RTLS/ASDS mode. It's not as simple as saying "Hey, we're going to throw this one away, let's max it out!". They will likely have to go through another process of certifying the upper stage for anything more than about 25,000kg, which is the max payload they need for DoD missions. The payload weight of dual comm-sat stacks vs a Red Dragon to mars is similar, so they don't need to be able to throw anything more than their customers need. When / If something as specialized as a fully fledged Bigelow module comes around, they contract will be lucrative enough that extra certification / integration is a given.

It's funny, that maximum payload limitation. That for GTO too? That's about Proton's (or Delta IV's) maximum payload... to LEO, not GTO. Which is (almost) the same thing as an ISS-class module to GSO. Or two Hubbles. On second thought, with reusability, if they underburn the central core to slow it down to recover it... it could be a "simple" Proton-class launcher. Only reusable.

 

Rune. I wonder why would the DoD want a Hubble on GSO...

Edited January 3, 2016 by Rune

[saabstory88]

7 minutes ago, Rune said:

It's funny, that maximum payload limitation. That for GTO too? That's about Proton's (or Delta IV's) maximum payload... to LEO, not GTO. Which is (almost) the same thing as an ISS-class module to GSO. Or two Hubbles. On second thought, with reusability, if they underburn the central core to slow it down to recover it... it could be a "simple" Proton-class launcher. Only reusable.

 

Rune. I wonder why would the DoD want a Hubble on GSO...

That is 25,000kg on the payload adapter, which has nothing to do with capability to any particular orbit. As I mentioned earlier, the GTO capability of the Falcon Heavy is probably around 11,000kg - 11,500kg. The 25,000kg max payload is going to be LEO only sort of thing. They only need to max out their payload adapters for NRO/DOD LEO missions. As I've said before, the Falcon Heavy is going to be used as something to try to put things like the Proton, Ariane 5, Atlas V 500 series, and Delta IV-H out of business. It doesn't need to get anywhere near the payload cap on the SLS. As we have learned, SpaceX doesn't do intermediary boosters. They canned the F1e and F5 because they wanted to go straight for the F9. They didn't need training wheels. They won't bother trying to get the FH to throw anything bigger than what it needs to make money, it makes way more sense to just build the BFR, and be done with it.

[fredinno]

2 minutes ago, saabstory88 said:

That is 25,000kg on the payload adapter, which has nothing to do with capability to any particular orbit. As I mentioned earlier, the GTO capability of the Falcon Heavy is probably around 11,000kg - 11,500kg. The 25,000kg max payload is going to be LEO only sort of thing. They only need to max out their payload adapters for NRO/DOD LEO missions. As I've said before, the Falcon Heavy is going to be used as something to try to put things like the Proton, Ariane 5, Atlas V 500 series, and Delta IV-H out of business. It doesn't need to get anywhere near the payload cap on the SLS. As we have learned, SpaceX doesn't do intermediary boosters. They canned the F1e and F5 because they wanted to go straight for the F9. They didn't need training wheels. They won't bother trying to get the FH to throw anything bigger than what it needs to make money, it makes way more sense to just build the BFR, and be done with it.

I still would have wanted a Falcon V though... It would be a good Soyuz-level rocket.

[Rakaydos]

On 1/1/2016 at 10:11 AM, fredinno said:

9 minutes ago, fredinno said:

I still would have wanted a Falcon V though... It would be a good Soyuz-level rocket.

 

Did they need a Soyuz level rocket? Considering the DV to orbit gets more efficent the larger the rocket mass (all else being proportional, due to square cube law vs air drag) I can see it being more cost effective to make the F9 their smallest option.

So packages go from Falcon 9 cubesat bundle and multi-sat launch, Falcon 9 reusable, Falcon heavy multisat, Falcon heavy, Falcon heavy (expended core), and MCT (Cargo).

There might be a bit of a gap between MCT Cargo and Falcon Heavy(expendable), if the MCT actually meets the "100 tons to mars surface" target numbers. Even if that assumes LEO refueling flights, that's looking at "Lift a Lunar/Lagrange space elevator in a single launch" lift capacity.

[sojourner]

Falcon 5 was just Falcon 9 with only 5 first stage engines instead of nine. Not much point building it if you can reuse the first stage in any case.

[Rune]

3 hours ago, Rakaydos said:

There might be a bit of a gap between MCT Cargo and Falcon Heavy(expendable), if the MCT actually meets the "100 tons to mars surface" target numbers. Even if that assumes LEO refueling flights, that's looking at "Lift a Lunar/Lagrange space elevator in a single launch" lift capacity.

Not necessarily. If I read those "100mT to Mars surface comments" right, they could very well be accomplished by landing a 100mT spaceship that can be reused, with maybe a 50mT of actual payload (I.E: ISRU plant, you only need to send the one). Said spacecraft, while having the same mass empty as an Apollo lunar stack, could hold the ~400mT of propellant that could get it to Mars with 1.5km/s left for a powered aero-assisted descent. Even doubling those numbers to 100mT actual payload on the surface, launch mass is not that far away form Saturn or SLS at ~200mT. The incredible 15m diameter talked about is just an aerodynamic and tankage efficiency plus, IMO, and orbital refueling and ISRU the things that actually make it doable.

 

Rune. As long as you are going outside of land transport capabilities, why not go really outside...

Edited January 3, 2016 by Rune

[fredinno]

6 hours ago, Rakaydos said:

Did they need a Soyuz level rocket? Considering the DV to orbit gets more efficent the larger the rocket mass (all else being proportional, due to square cube law vs air drag) I can see it being more cost effective to make the F9 their smallest option.

So packages go from Falcon 9 cubesat bundle and multi-sat launch, Falcon 9 reusable, Falcon heavy multisat, Falcon heavy, Falcon heavy (expended core), and MCT (Cargo).

There might be a bit of a gap between MCT Cargo and Falcon Heavy(expendable), if the MCT actually meets the "100 tons to mars surface" target numbers. Even if that assumes LEO refueling flights, that's looking at "Lift a Lunar/Lagrange space elevator in a single launch" lift capacity.

MCT is a pipe dream, TBH.

 

Either way, the death of Falcon 1e and Falcon 5 was kind of a bad decision, in my opinion. SpaceX could have set the development of Falcon 1e and 5 after developing Falcon 9 and Falcon Heavy (the original Falcon 1 would be kept, to launch the Orbcomm and ORS sats that were intended for it), to take the main sectors of the market, then move towards cubesats (Falcon 1e would likely be a cubesat launcher it it used Falcon 9-style powered 1st stage powered landings), while Falcon 5 would have been useful for LEO flights- of course, you can still launch LEO sats with a Falcon 9, but its 15T to LEO capability is 'somewhat' overpowered. They literally launched the entire Orbcomm contract in two launches- which can be a bad thing, since these LEO sats might need more fuel to do inclination changes to reach their required orbits. This can actually end up LESS efficient.

Not to mention DOD has a large percentage of their launches in the 401 and 501 Atlas V configs, (almost half of Atlas V launches are 401s), which is also Soyuz- level. I stand by my word there is a market for Falcon 5. (Not the original, Delta II-level rocket though, but a full thrust version using Merlin 1Ds, and with 8-10 to to LEO capacity)

 

Also, they could use the same Falcon 9 tanking diameters for Falcon 5 (and likely common engines from Falcon 9 and 1, too)

[sojourner]

Again. Falcon 5 is a Falcon 9, just with less first stage engines.  So if you're recovering the first stage anyway, why bother?

Edited January 4, 2016 by sojourner