Blue Origin Thread (merged)

[wumpus]

46 minutes ago, Elukka said:

From what I figure they're simply the numbers the launchers would have if launched in expendable configuration, i.e. numbers that can be compared to other launch vehicles. I don't get how any of your conclusions follow. I would not expect that they would lie about these numbers either.

It doesn't change my point at all.  There's no point in launching a non-recoverable Falcon9 if a Falcon Heavy can lift such a mass *and* recover all three boosters.  The assumption follows that a fully-recoverable Falcon Heavy will deliver less than 22.8 tons to LEO.  No idea if the prices change depending if you allow for recovery or not (I'd assume they do, but it is *amazing* that they make pricing public at all).

I also suspect that a "two out of three recovery" Heavy Falcon will get you closer to 50 tons than 22.8 tons and destroy roughly the same amount of equipment as the Falcon 9 single-use.

[tater]

That's what I meant, use a end of life F9 as the FH core, and expend it.

[Kryten]

2 minutes ago, tater said:

That's what I meant, use a end of life F9 as the FH core, and expend it.

FH core is not interchangable with F9 core.

[Wjolcz]

How many times a Merlin engine can be reused, or rather for how many hours can it run until the nozzle is full of holes? Their nozzles are ablative so I would imagine they don't have the same life time as, for example, the Space Shuttle engines (which are not ablative and fuel-cooled instead afaik).

[Kryten]

14 minutes ago, Veeltch said:

How many times a Merlin engine can be reused, or rather for how many hours can it run until the nozzle is full of holes? Their nozzles are ablative so I would imagine they don't have the same life time as, for example, the Space Shuttle engines (which are not ablative and fuel-cooled instead afaik).

Only Merlin-1A was ablative, the current versions are all regeneratively cooled (i.e. with fuel).

[Elukka]

1 hour ago, wumpus said:

It doesn't change my point at all.  There's no point in launching a non-recoverable Falcon9 if a Falcon Heavy can lift such a mass *and* recover all three boosters.  The assumption follows that a fully-recoverable Falcon Heavy will deliver less than 22.8 tons to LEO.  No idea if the prices change depending if you allow for recovery or not (I'd assume they do, but it is *amazing* that they make pricing public at all).

I also suspect that a "two out of three recovery" Heavy Falcon will get you closer to 50 tons than 22.8 tons and destroy roughly the same amount of equipment as the Falcon 9 single-use.

No, that doesn't follow at all. All it means is that a Falcon 9 in expendable configuration can lift 22.8 tonnes. Would an expendable F9 be launched in a future situation where reuse is in full swing and Falcon Heavy operational? Probably not. Does that have any bearing of how much an expendable F9 can lift? No.

Edited May 1, 2016 by Elukka

[tater]

1 hour ago, Kryten said:

FH core is not interchangable with F9 core.

Makes sense, I thought it might be a possible modification/refurb (I thought this for no actual reason whatsoever  ).

[AngelLestat]

24 minutes ago, Kryten said:

FH core is not interchangable with F9 core.

Why not?  due the aerodynamic cone?

Difference materials needs?

[sojourner]

What aerodynamic cone? The core has the second stage above it.  The FH core has structural differences to allow for the side boosters and (depending on the artwork we've seen) may be taller than the standard F9 core.

[AngelLestat]

I mean the aerodynamic cone added to the side boosters.

I read all the info in the wiki and it does not said nothing about differences between the center core and the side boosters.
You may remove the legs and the aerodynamic grid fins.. if you dont want to recover the center core.. but I can not find any other difference between the 3 first stage cores.
 

 

[tater]

More likely the structure needed to secure the side boosters. By placing those structures on a purpose-built core, they save that mass on the regular F9 launches.

[sojourner]

 

the side boosters are definitely a different size than the core stage and not interchangeable.

[AngelLestat]

2 hours ago, tater said:

More likely the structure needed to secure the side boosters. By placing those structures on a purpose-built core, they save that mass on the regular F9 launches.

In that case, you place a reinforcement ring just in that section where the joints are with the 2 side connections ready, the extra weight is negligible.

Take a look to this:

The legs small joints can be fixed to all the core basic structures, the same goes for adapters in the strap connections or grid fins. So the basic core structure is always the same (which reduce the manufacture cost) and then you add or remove the parts that you dont use like legs, fins, straps, crossfeed, etc.

It will be silly if you need to make a whole core just to add an adapter in one side of the core or a reinforcement ring.

57 minutes ago, sojourner said:

the side boosters are definitely a different size than the core stage and not interchangeable.

The official page graphic, show that all cores are the same size, you can not count the aerodynamic cone.
The info of all sites that I saw show the same and they don't give any details on differences between cores.
But maybe I am wrong.. if you have a source that said they are different I will like to read it.
Elon Musk idea was always had the same core to reduce manufacture and development cost.

Edited May 2, 2016 by AngelLestat

[CptRichardson]

Excuse me, but thirteen metric tons to Martian transfer orbit? Please excuse me while I change my brown pants for something more suitable for the occasion.  That is mind-bogglingly insane.  That's literally 'more power than god' grade crazy.  Forget Red Dragon, we could probably land a bus on Mars with that kind of power. Hell, even the 50 metric tons to LEO is just mind-bogglingly insane, especially given that we know Falcon Heavy will fly consistently (compared to the probably soon to be canceled SLS). I'm actually rather terrified of just how over the top insane the MCT is going to be if these "NOT EVEN MY FINAL FORMS" Falcon-family rockets can actually deliver on these promises.   

[wumpus]

12 hours ago, AngelLestat said:

It will be silly if you need to make a whole core just to add an adapter in one side of the core or a reinforcement ring.

The center has to support everything the Falcon9 booster does, plus an additional  25 or more tons of cargo.  The sides do not (not even the upper stage).  I suspect some of those struts in the rocket will either be removed ("Munzted in EE terms") or made smaller/lighter (because they can be weaker).  Or possibly the side boosters contain extra fuel roughly equal to what the upper stage carries (I suspect this makes more sense).

Keeping costs low by maintaining a single parts bin is important.  But dry mass is likely more critical.

[Spaceception]

Seeing as how the Falcon heavy will put out 5.1 million lb thrust, making it just 2.6 million lb thrust less powerful than the Saturn V, I'm kinda scared to see how powerful the MCT will be, it's gonna make the SLS look like a Redstone.

[KSK]

The MCT is going to be Nova levels of insanity awesome, if not more, I reckon.

[Spaceception]

2 minutes ago, KSK said:

The MCT is going to be Nova levels of insanity awesome, if not more, I reckon.

They want it to put 100 tons on Mars, it'll definitely overpower the Nova.

[AngelLestat]

6 hours ago, wumpus said:

The center has to support everything the Falcon9 booster does, plus an additional  25 or more tons of cargo.  The sides do not (not even the upper stage).  I suspect some of those struts in the rocket will either be removed ("Munzted in EE terms") or made smaller/lighter (because they can be weaker).  Or possibly the side boosters contain extra fuel roughly equal to what the upper stage carries (I suspect this makes more sense).

Keeping costs low by maintaining a single parts bin is important.  But dry mass is likely more critical.

The max force is on the straps joints of the 3 cores, that ring section should be stronger in the 3 cores, once you know you can manage those forces the weight of the second stage and payload should be negligible vs max-q forces or different structure vibes that all stages should face.
As I said.. I cant find any document mentioning differences between the center core and the booster cores.
I also search info in the Delta IV Heavy, all info seems to point that all cores are the same.
So unless someone find info disproving this, we should keep the basic spacex idea about one common core to rule them all

-----------------------------------------------------------------------------------------

I was thinking in Crossfeed.

I read different discussion where people provide some reasons why it should be very hard or pointless to implement this.
But I can´t find a single valid case on those arguments with the exception that it will add "more complexity", but even the word "complexity" seems exaggerated in this case.
Reddit 1, Reddit 2, Reddit 3

Some arguments that I hear said that crossfeed can only save a % of the center core fuel. They also mention that you need to feed some engines, like 3 engines (left booster), 3 engines (center) and 3 the right booster..  but it does not seems to have any sense.
Why you will have a independent line of fuel from the main tank to your 9 merlins + 2x3 extra lines that will connect to the center core engines?
With the incredible valve and connections that it will demand that approach.
Some even said that you need extra pumps to transfer fuel from one rocket to the other.

But as all that seems crazy for me.. I made my own graphic and approach of how I think it should be done (which is pretty simple in principle)

Valves and different mechanism needed are not included in the graphic.
If we made the crossfeed after the tank exit and before the fuel distribution we dont have any of those issues. We just need to increase the diameter of the main tank hoses a 20%
In operation the center core pipes that come from the tanks will be closed, so the helium of the other 2 booster are keeping the fuel pressure needed in the 27 merlin feed hoses.
Before separation crossfeed valves are closed, the center core valves open and you expel the 2 connections between the cores.

Of course this will need sensors, electro valves and different passive mechanism to add safety, all that controlled with a power algorithm that it will be able to deal with many different problem using different techniques. But this is like super normal in any engine, from a car to a 747, in fact a 747 is several times more complex than a rocket, so complexity does not add risk if the system has enough experience.

Thoughts?

[PB666]

1 hour ago, AngelLestat said:

The max force is on the straps joints of the 3 cores, that ring section should be stronger in the 3 cores, once you know you can manage those forces the weight of the second stage and payload should be negligible vs max-q forces or different structure vibes that all stages should face.
As I said.. I cant find any document mentioning differences between the center core and the booster cores.
I also search info in the Delta IV Heavy, all info seems to point that all cores are the same.
So unless someone find info disproving this, we should keep the basic spacex idea about one common core to rule them all

-----------------------------------------------------------------------------------------

I was thinking in Crossfeed.

I read different discussion where people provide some reasons why it should be very hard or pointless to implement this.
But I can´t find a single valid case on those arguments with the exception that it will add "more complexity", but even the word "complexity" seems exaggerated in this case.
Reddit 1, Reddit 2, Reddit 3

Some arguments that I hear said that crossfeed can only save a % of the center core fuel. They also mention that you need to feed some engines, like 3 engines (left booster), 3 engines (center) and 3 the right booster..  but it does not seems to have any sense.
Why you will have a independent line of fuel from the main tank to your 9 merlins + 2x3 extra lines that will connect to the center core engines?
With the incredible valve and connections that it will demand that approach.
Some even said that you need extra pumps to transfer fuel from one rocket to the other.

But as all that seems crazy for me.. I made my own graphic and approach of how I think it should be done (which is pretty simple in principle)

Valves and different mechanism needed are not included in the graphic.
If we made the crossfeed after the tank exit and before the fuel distribution we dont have any of those issues. We just need to increase the diameter of the main tank hoses a 20%
In operation the center core pipes that come from the tanks will be closed, so the helium of the other 2 booster are keeping the fuel pressure needed in the 27 merlin feed hoses.
Before separation crossfeed valves are closed, the center core valves open and you expel the 2 connections between the cores.

Of course this will need sensors, electro valves and different passive mechanism to add safety, all that controlled with a power algorithm that it will be able to deal with many different problem using different techniques. But this is like super normal in any engine, from a car to a 747, in fact a 747 is several times more complex than a rocket, so complexity does not add risk if the system has enough experience.

Thoughts?

Nice pictures. The problem is that when you jettison the boosters you center tank is full, ISP has raised a little, but the problem the remaing rocket now is as heavy as a falcon at launch but with the heavy payload and just a little more ISP, you wont be gaining much speed for a while. IF falcon can power up to 7402 kN and hold velocity might not be so bad, but how do you pour on velocity after max Q. Lets say you have 740kt falcon with a 100% larger second stage , you are not going to be accelerating quickly. 

[softweir]

1 hour ago, PB666 said:

Nice pictures. The problem is that when you jettison the boosters you center tank is full, ISP has raised a little, but the problem the remaing rocket now is as heavy as a falcon at launch but with the heavy payload and just a little more ISP, you wont be gaining much speed for a while. IF falcon can power up to 7402 kN and hold velocity might not be so bad, but how do you pour on velocity after max Q. Lets say you have 740kt falcon with a 100% larger second stage , you are not going to be accelerating quickly. 

By the time the boosters have been jettisoned, the core and payload will be high up, moving fast, and moving downrange faster than it is moving up. Most importantly, all that fuel has been lifted up high and got moving fast - that adds more than a little to the usefulness of its thrust and I_sp.

Regarding the complexity of fuel cross-feed: I can't find it now, but I remember a quote along the lines of "the turbines don't like it". Shutting off one source of fuel and turning on another is not a simple business - SpaceX have to make certain that there is no drop nor spike in pressure during that transition. An added complexity is that the fuel coming in from the boosters' tanks is coming through a more convoluted feed train, which is liable to slow it down. For the core's engines to work properly, SpaceX have to make sure that doesn't happen, without adding heavy and over-complex systems to the boosters. This is the sort of engineering task which can seem easy until it is tried, when the sheer complexity and number of unpredictable problems makes it clear that it is not easy.

Edited May 3, 2016 by softweir

[CatastrophicFailure]

2 hours ago, PB666 said:

Nice pictures. The problem is that when you jettison the boosters you center tank is full, ISP has raised a little, but the problem the remaing rocket now is as heavy as a falcon at launch but with the heavy payload and just a little more ISP, you wont be gaining much speed for a while. IF falcon can power up to 7402 kN and hold velocity might not be so bad, but how do you pour on velocity after max Q. Lets say you have 740kt falcon with a 100% larger second stage , you are not going to be accelerating quickly. 

It seems to me once you've gotten that far, shutting off crossfeed early enough for the core to use enough of its own fuel is a simple engine management software issue. Even without doing that, I, and I'm sure many others, have designs similar to this in upscaled KSP, and it works quite well. Like @softweir said, once you've got the core that high and that fast, it adds much to the usefulness. 

 

On a different note, why would it not be good to have the boosters feeding directly into the core tanks instead of the engines?

[Frybert]

21 minutes ago, CatastrophicFailure said:

On a different note, why would it not be good to have the boosters feeding directly into the core tanks instead of the engines?

Thats always pretty much how I imagined it working TBH.

[Rakaydos]

Mainly because that would involve pumping fuel/oxidiser "uphill", under however many Gs the rocket is pulling before separation. The booster tanks would have to be drained from a point higher than the core tanks are pumped into, and the full core tanks have the maximum amount of pressure being applied to resist being pumped into.

[Streetwind]

I've honestly not seen much in the way of official statements regarding crossfeed either, but it really looks like it's not going to happen anymore. Elon Musk himself confirmed that the payload numbers posted last weekend were explicitly without crossfeed, and that it's not needed anymore. You can pretty much consider it officially cancelled at this point.

As to why, I couldn't say. I'm not knowledgeable enough in fluid dynamics to make statements about that. But considering Musk is a perfectionist, and SpaceX has a reputation of making outlandish concepts work - if they decided to drop this one, there ought to be a very good reason for it.