Commercial HLV and R&D

[ugordan]

A B-2 stealth bomber can carry over 18 tons of bombs to a height greater than 50,000 ft and a speed of up to .95 Mach, which is enough weight for a Centaur upper stage and a payload (although not enough volume).

Which would then drop from the sky like a brick due to its low T/W ratio, before it could pick up any significant speed and haul a$$ out of the atmosphere. Hypothetically speaking, of course.

[clongton]

I've been following the discussion of an air-launch payload and wondered how it fit into the title of this topic, so I decided to take a look at the question posed by the person who started this thread.

Back on page 1, post #1, yg1968 asked:

What would be examples of R&D on an HLV project? "

I must admit that while I initially considered this discussion to be off topic, but when I re-read the first post I had to admit that I had prejudiced my self my thinking only in terms of rocket launch vehicles. But the question certainly allows this air launch to be explored, so long as we are talking "heavy lift".

Now we usually think of "heavy lift" in terms of the size of the rocket launch vehicle, but for the purpose of pursuing this line of thought, I think we should define heavy lift in terms of useful mass to LEO. So before I express my ideas about the air launch, can we get a consensus of what that might be? How much *useful* mass should actually enter orbit before the launch vehicle can be considered "heavy lift"?

This is an interesting idea, so I think it is appropriate, if we are going to look at this, to first determine what is an acceptable IMLEO to qualify.

Let's discuss that for a bit, come to a consensus and then go from there back to this idea of air launch from a specially designed "heavy lift" aircraft. This could be interesting.

[rklaehn]

A B-2 stealth bomber can carry over 18 tons of bombs to a height greater than 50,000 ft and a speed of up to .95 Mach, which is enough weight for a Centaur upper stage and a payload (although not enough volume).

Which would then drop from the sky like a brick due to its low T/W ratio, before it could pick up any significant speed and haul a$$ out of the atmosphere. Hypothetically speaking, of course.

You could add some hydrocarbon drop tanks and use a TAN augmented version of the RL-10. That would give you a T/W of more than 1.

[Robotbeat]

A B-2 stealth bomber can carry over 18 tons of bombs to a height greater than 50,000 ft and a speed of up to .95 Mach, which is enough weight for a Centaur upper stage and a payload (although not enough volume).

Which would then drop from the sky like a brick due to its low T/W ratio, before it could pick up any significant speed and haul a$$ out of the atmosphere. Hypothetically speaking, of course.

You could add some hydrocarbon drop tanks and use a TAN augmented version of the RL-10. That would give you a T/W of more than 1.

Part of the advantage of air-launching is that you may be able to have a SSTO-vehicle without TAN or something like that.

[rklaehn]

Part of the advantage of air-launching is that you may be able to have a SSTO-vehicle without TAN or something like that.

Assisted SSTO is pretty challenging even if you do a high-altitude subsonic airdrop (once your first stage contributes significant velocity, it is no longer SSTO).

The single engine centaur has a T/W of less than 0.5. Even the two engine centaur has a T/W of about 1. None of these stages will go anywhere without adding more engines or somehow augmenting the engine(s) they already have. And despite its age, the centaur stage is pretty close to the state of the art in propellant mass fraction. I guess you could airdrop a dual engine centaur with solids to launch a tiny (~1t) payload. But then the question is why that should be cheaper than just using a first stage and launching 10t using the same centaur stage.

[rklaehn]

I've been following the discussion of an air-launch payload and wondered how it fit into the title of this topic, so I decided to take a look at the question posed by the person who started this thread.

Back on page 1, post #1, yg1968 asked:

What would be examples of R&D on an HLV project? "

I must admit that while I initially considered this discussion to be off topic, but when I re-read the first post I had to admit that I had prejudiced my self my thinking only in terms of rocket launch vehicles. But the question certainly allows this air launch to be explored, so long as we are talking "heavy lift".

Now we usually think of "heavy lift" in terms of the size of the rocket launch vehicle, but for the purpose of pursuing this line of thought, I think we should define heavy lift in terms of useful mass to LEO. So before I express my ideas about the air launch, can we get a consensus of what that might be? How much *useful* mass should actually enter orbit before the launch vehicle can be considered "heavy lift"?

Maybe the same as 4 direct or 2 ares launches per year, so about 300-400t?

[Robotbeat]

I've been following the discussion of an air-launch payload and wondered how it fit into the title of this topic, so I decided to take a look at the question posed by the person who started this thread.

Back on page 1, post #1, yg1968 asked:

What would be examples of R&D on an HLV project? "

I must admit that while I initially considered this discussion to be off topic, but when I re-read the first post I had to admit that I had prejudiced my self my thinking only in terms of rocket launch vehicles. But the question certainly allows this air launch to be explored, so long as we are talking "heavy lift".

Now we usually think of "heavy lift" in terms of the size of the rocket launch vehicle, but for the purpose of pursuing this line of thought, I think we should define heavy lift in terms of useful mass to LEO. So before I express my ideas about the air launch, can we get a consensus of what that might be? How much *useful* mass should actually enter orbit before the launch vehicle can be considered "heavy lift"?

This is an interesting idea, so I think it is appropriate, if we are going to look at this, to first determine what is an acceptable IMLEO to qualify.

Let's discuss that for a bit, come to a consensus and then go from there back to this idea of air launch from a specially designed "heavy lift" aircraft. This could be interesting.

A 74-400 has a top speed of about .92 mach. Some 747 variants have supposedly gone as high as 60,000 feet. Of course, neither of these are going to happen with a cargo of over 100 tons without some major mods.
And with a 100-ton single stage, you're not likely to get much more than 10 tons into orbit, ESPECIALLY if it's a RLV. Lots of work needed.

You really want to get to Mach 3 and 90,000 feet so you can get more useful cargo into orbit. More like SR-71 territory than 747 territory. Probably best to just make it TSTO with the first stage being just a bunch of supersonic air-breathing engines with fuel tanks and recovery hardware so it can fly back to the launch site.

rklaehn: You're right. Best to just have a real first stage (hopefully it can be recovered and reused without refurbishment, though).

[jongoff]

Hey guys,
I'm with Chuck at least on the air-launch discussion being not very relevant to this thread.  While you theoretically could do an air-launched concept that got up into "Heavy Lift" size ranges....it's a bit of a stretch.

I disagree with him on the whole "myth of reusability" thing, though.  Of course, I wasn't even talking about full "gas-and-go" reusability, but the same sort of recoverability options that study after study over the past 50 years have indicated could start making sense once you start talking about more than 10-12 flights per year.  Sure, reuse on the Space Shuttle hasn't worked out very well at extremely low flight-rates.  But once you start getting anywhere close to the flight rates that have been discussed for the more expansive beyond LEO mission, things start becoming more interesting.

At least for the Mid-Air Recovery stuff LM and now ULA were studying, there was a pretty strong argument that it would reduce costs and make it easier to get to high flight rates. 

~Jon

[clongton]

Hi Jon
You lost me. "myth of reusability" thing?

Hey guys,
I'm with Chuck at least on the air-launch discussion being not very relevant to this thread.  While you theoretically could do an air-launched concept that got up into "Heavy Lift" size ranges....it's a bit of a stretch.

I disagree with him on the whole "myth of reusability" thing, though. 
~Jon

[jongoff]

Hi Jon
You lost me. "myth of reusability" thing?

Your quote of John Shannon back in Reply #184, back on Page 13.

Sorry, I've been meaning to reply, but between trying to get some abstracts in for a conference, sick kids, and trying to get our new test trailer project (and tanks projects) caught up to schedule, I've been swamped.  Let me try and give a more thorough reply later.

~Jon

[Robotbeat]

You can't really get to heavy-lift-ability with a 747-sized airlauncher. What you really need is a totally custom-built mostly airbreathing (and hypersonic) first stage. Perhaps you cross-feed propellant from the first-stage's tanks to the attached upperstage and have the upper stage's engines burn that for a little while to provide another boost before stage separation. That might let you get into the medium-to-heavy-launch lift capability (i.e. 50 tons to LEO... okay, chuck doesn't like that term being used for heavy lift, but it's still much more than we have available _today_) while keeping the upper stage's mass to around 150 tons.

The whole issue with heavy-lift is that you generally have to build it like a skyscraper, which is what makes it usually unsustainable. In order to avoid that, you have to worry about take-off weight, as well.

[clongton]

Hi Jon
You lost me. "myth of reusability" thing?

Your quote of John Shannon back in Reply #184, back on Page 13.

Sorry, I've been meaning to reply, but between trying to get some abstracts in for a conference, sick kids, and trying to get our new test trailer project (and tanks projects) caught up to schedule, I've been swamped.  Let me try and give a more thorough reply later.

~Jon

Ok Jon;
Looking forward to it.

[clongton]

That might let you get into the medium-to-heavy-launch lift capability (i.e. 50 tons to LEO... okay, chuck doesn't like that term being used for heavy lift,

My understanding of "heavy lift" was formed by the design engineers who coined the phrase, but the context of the definition was vertically launched rockets. For a horizontal air assist launch I might be willing to accept a different definition. That's why I asked for the contextual discussion.

[Robotbeat]

That might let you get into the medium-to-heavy-launch lift capability (i.e. 50 tons to LEO... okay, chuck doesn't like that term being used for heavy lift,

My understanding of "heavy lift" was formed by the design engineers who coined the phrase, but the context of the definition was vertically launched rockets. For a horizontal air assist launch I might be willing to accept a different definition. That's why I asked for the contextual discussion.

Fair enough. 100 tons is roughly what a 747 could carry. What you'd need for even 50 tons in LEO is a Mach 6, 100,000 feet altitude air-launcher with a 150 ton payload capacity (~100 tons for the "upper" stage, ~50 tons for actual orbital payload with a very efficient hydrolox engine), and even then, it'd be a very low orbit.

[mmeijeri]

HLV: n. "mine's bigger than yours"

[MP99]

How about we aim for DIVH / Shuttle / F9H sized payloads, say 25mT.

Despite the names of two of the vehicles, it's below most definitions of "heavy" (except Martijn), but is plainly a challenging payload size for this type of launch.

Extra credit for discussion of what would be necessary for your launcher to double, and double again it's payload, ie 50mT & 100mT.

Martin

[Robotbeat]

How about we aim for DIVH / Shuttle / F9H sized payloads, say 25mT.

Despite the names of two of the vehicles, it's below most definitions of "heavy" (except Martijn), but is plainly a challenging payload size for this type of launch.

Extra credit for discussion of what would be necessary for your launcher to double, and double again it's payload, ie 50mT & 100mT.

Martin

This kind of depends on whether we're allowing hypersonic air launch vehicles. A hypersonic airlauncher could realistically put 50 tons in LEO with just a single "upper" stage. Anything more, and you'd be back to building your rocket like a skyscraper.

A subsonic/transonic airlauncher made out of a modified 747 could probably do about 20 tons. (although it might need another stage and a really good hydrolox engine) You can't realistically scale up your airlauncher much bigger than a 747. The An-225 can carry almost 200 250 tons, but it's max speed and service ceiling are both lower than the 747. I'd guesstimate no more than 30 35 tons (and only just barely) could be delivered to a low orbit with a heavily modified An-225.

[A_M_Swallow]

Heavy lift 100 mT to LEO
Light heavy 50 mT to 75 mT

A proof of concept system using off the shelf components can have a smaller payload.
The number of engines is a design variable.
The launch aircraft does not need to cross the Atlantic so it only needs to carry sufficient fuel for half an hour to an hours flight.

[Chris Bergin]

Thread about HLVs. No more on subjects that are covered elsewhere.

[Lampyridae]

I can't see a business case for an RLV with a payload of more than 20 tonnes, at least at present. In astronaut terms, enough to take 7 astros up with a decent escape system. I could see RLV being used as elements of an HLV, like Energiya's strap-ons and of course the SRBs for shuttle. Of course the SRBs are non starters, but flyback kerolox boosters can be introduced later. These same boosters can be used with an expendable core, eg Delta IV for 20+ tonnes, or individually with an expendable strap-on stage for small payloads. HLV still uses a disposable core, because it will just work out cheaper that way. I believe commonality and flexibility is key to RLV success. Kinda like SLI, though nobody gets passionate about "architectures" to LEO.

That's how a RHLV would get developed, but for the near term for commercial HLV, you still need:
A. Shuttle
B. SDHLV (sort-of RHLV anyway)
C. Orion (or similar "anchor" payload to fly regularly... shuttle minus engines?    )

Otherwise there's just no justifying it. SDHLV is the only way to afford it, flying shuttle is the only way to keep the infrastructure until we need it (in other words, until we get a heavy crew vehicle) and all of this undercuts COTS.