Combined atmospheric winged launcher (sort of a non SSTO all recoverable craft)

[11of10]

Well guys, I've been tossing this idea around in my head for quite a while.

It's not really a challenge, since I can't offer my attempt, because my computer can't really handle the whole RSS/Realism Overhaul, but here goes:

With RSS installed, with FAR, TAC, DRE et cetera,

is it feasible to make a multistage winged launcher?

Entirely reusable.

For instance, you get a B-52 to haul something high up. Then it starts it's own scramjet for instance, that carries it further, then it detaches the scramjet part, which turns back to base, and you fly the rest of the way on rocket power.

Could a atmospheric launched sort of cheap launcher be made that way, for real Earth?

Idea isn't to make a Single Stage craft, but sort of like something that SpaceX wants to make with Grasshopper, or Virgin Galactic does with White Knight/SpaceShipN combo, only orbital, and only with off the shelf (more or less) parts.

Any comments, ideas?

Edit: Sorry for puting it here, the game related part is just a "testing ground" for this idea.

[Nibb31]

Basically what you are proposing is an orbital version of SpaceShipTwo. In real-life, this doesn't scale up well.

Remember that getting to orbit is about speed, not altitude. A White Knight type of aircraft is subsonic, topping at 900km/h, which is minimal compared to the 27000km/h that you need to reach orbit. You save a few hundred km/s of delta-V thanks to the lower drag at altitude, but your spaceplane is still going to need to perform 90% of the acceleration to orbital speed. Therefore, it's still going to need to be 90% as big and heavy as a conventional Falcon 9, Delta IV, etc... However, because your spaceplane has the added weight of a TPS, wings, landing gear, and all the hydraulic stuff that goes with it, it's going to be much heavier than a conventional Falcon 9, Delta IV, etc...

You're going to need a carrier aircraft that is big enough to carry this fully fueled spaceplane. It will be an order of magnitude larger than the largest aircraft ever built. It will be super expensive to design, build, and operate. It will need a dedicated airport with a reinforced runway and rocket fuel facilities and the biggest hangar in the world where it will spend most of its time between launches.

And then, there are all sorts of failure modes associated with air-launch... All in all, your carrier aircraft is just a reusable super-expensive low-performance first stage booster. You have increased cost, increased complexity, increased risk. In the end, you would get more extra delta-V by strapping a couple of cheap SRBs on to an SSTO spaceplane.

[magnemoe]

Yes, however two other benefit one is that you can fly to and launch from equator or other places, the other is that you don't need an rocket engine who works at 1 bar.

Downside is as Nib31 says you need a special plane, B52 can only drop 20 ton or something.

it makes more sense if you have an fast and high flying plane, however they get far more expensive to build.

Something like Falcon 9 reuseable is far simpler.

[11of10]

Well, I haven't really explained it properly it seems. B-52 was just a place holder of sorts.

Ideally, you'd use some relative of SR-71 (I know, it's expensive as hell to fly it) to get to as high speed as possible on turbojets, then second stage uses ramjets or scramjets if possible, and finally third stage goes the rest of the way on rocket power.

I imagine it might be useful for launching small satellites or supplies into orbit cheaply.

[cantab]

Something like a Tu-160 might do well. A 600 m/s start at 12 km up isn't huge, but I reckon it'd translate to a 10-15% payload increase. With a 40 ton payload on the plane you could get a few tons into orbit, rather more than the Pegasus's half-ton payload. In terms of payload to orbit, I think the aircraft cargo capacity is more important than its height or speed.

As magnemoe says, the bigger benefits are on secondary factors. Launching from a choice of latitudes and above the weather, and being able to use a first rocket engine optimised for higher altitudes. And not having the expense of a ground launchpad.

[Nibb31]

Well, I haven't really explained it properly it seems. B-52 was just a place holder of sorts.

Ideally, you'd use some relative of SR-71 (I know, it's expensive as hell to fly it) to get to as high speed as possible on turbojets, then second stage uses ramjets or scramjets if possible, and finally third stage goes the rest of the way on rocket power.

I imagine it might be useful for launching small satellites or supplies into orbit cheaply.

There were plans to use the old XB-70 Valkyrie for that before it was cancelled. But even launching from Mach 3 doesn't give you a huge benefit compared to just making a slightly bigger first stage or adding SRBs, and it would only be useful for very small payloads.

The CIA planned to use SR-71s to launch MD-21 recon drones over China, but the plan was cancelled when they found out the hard way that there were serious difficulties in launching from Mach 3.

There was also the Soviet Spiral project from the 70's, cancelled to make way for Buran.

Virgin intends to recoup some of the cost of their carrier plane with their LauncherOne project, but the economical viability of launching 200kg payloads is doubtful.

Edited August 13, 2014 by Nibb31

[Armchair Rocket Scientist]

Basically what you are proposing is an orbital version of SpaceShipTwo. In real-life, this doesn't scale up well.

Remember that getting to orbit is about speed, not altitude. A White Knight type of aircraft is subsonic, topping at 900km/h, which is minimal compared to the 27000km/h that you need to reach orbit. You save a few hundred km/s of delta-V thanks to the lower drag at altitude, but your spaceplane is still going to need to perform 90% of the acceleration to orbital speed. Therefore, it's still going to need to be 90% as big and heavy as a conventional Falcon 9, Delta IV, etc... However, because your spaceplane has the added weight of a TPS, wings, landing gear, and all the hydraulic stuff that goes with it, it's going to be much heavier than a conventional Falcon 9, Delta IV, etc...

You're going to need a carrier aircraft that is big enough to carry this fully fueled spaceplane. It will be an order of magnitude larger than the largest aircraft ever built. It will be super expensive to design, build, and operate. It will need a dedicated airport with a reinforced runway and rocket fuel facilities and the biggest hangar in the world where it will spend most of its time between launches.

And then, there are all sorts of failure modes associated with air-launch... All in all, your carrier aircraft is just a reusable super-expensive low-performance first stage booster. You have increased cost, increased complexity, increased risk. In the end, you would get more extra delta-V by strapping a couple of cheap SRBs on to an SSTO spaceplane.

That sums it up pretty well.

A winged vehicle has to deal with problems a rocket doesn't that limit its size. For example, as you scale up a vehicle its mass increases by the cube of the scale factor, but any area-related value (such as wing area, cross-sectional area) only increases by the square of the scale factor.

Drag is proportional to cross-sectional area, so larger vehicles need can fly faster with a given thrust-weight ratio. This is great for rockets, because it reduces their drag losses. However, the lift generated by a wing is also proportional to its area, so a larger aircraft needs to fly faster to generate enough lift. A higher stall speed means faster landings and takeoff, which means longer runways and more stress on the landing gear.

The result? Only two aircraft ever built - the Airbus A380 and the Antonov An-225 - have been heavier than a fully fueled Falcon 9 v 1.1.

I'm not sure how large an aircraft could theoretically be built, but a good bet is that your vehicle must absolutely be less than 1,000 tons - and that's a monster aircraft which needs purpose-built runways and costs billions of dollars. More likely it would only be a couple hundred tons, which severely limits its payload.

Now, subsonic air-launch is the easiest to pull off, but its absolutely worthless in terms of saving delta-v. Supersonic launch saves a bit more delta-v, but now that the carrier aircraft has to operate in radically different flight regimes both with and without its bulky payload, the design becomes even harder. Staging at supersonic speeds would also be tricky.

However, I've heard that Skylon's payload could potentially be doubled by using an expendable second stage. Presumably, Skylon would put itself on a very fast suborbital trajectory which allowed to to release the relatively small second stage and payload above the atmosphere. The second stage could probably be made reusable and still get more payload than an SSTO flight, but wings wouldn't fit well in a cargo bay.

Another idea is to use flyback boosters - boosters on a multi-stage rocket that can glide back to the launch site. These would give you a payload hit compared to a multi-stage vehicle that used airbreathing engines, but would be cheaper and potentially actually usable payloads over a few tons. On the other hand, I'm not sure how they stack up compared to propulsive landing. This method could also result in a very large upper stage that had to be heat-shielded for an orbital return, or a "middle stage" placed on an awkward trajectory like the center core of a Falcon Heavy.

[11of10]

Well, to be honest, the idea came when I first installed RSS + FAR and tried to play career, with all stock parts. After a few hours of cursing and jumping around Kerbin like a crazy Kerbal, I managed to scrounge enough science points to just barely launch a satellite into orbit.

Then I thought about this idea.

In the end, it remained an idea, and whole Realism Overhaul is much easier than what I tried.

Thanks for your oppinions guys, I can't help but feel a little dissapointed, but I completely forgot about the fact that RL jet engines aren't as good as the Kerbal ones... not to mention what would happen to an almost hypersonic launch platform at the moment when it launched it's cargo

[Chris P. Bacon]

Thought I'd leave this here http://www.stratolaunch.com/

Burt Rutan (of homebuilt aircraft, SpaceShipOne and White Knight fame) is designing the world's largest aircraft for Paul Allen of Microsoft to launch an Orbital Sciences booster rocket. (although my copy of Flying Magazine from 2012 states the rocket was to be built by SpaceX and carry a Dragon capsule)

The aircraft is basically a pair of 747-sized airframes bolted together at the wing, to launch the equivalent of what a Falcon 9 can do.

The company is a lot farther along than most of these ideas get though, at least they have the giant hangar built already.

Of course, there was always this sucker, who put quite a number of satellites in orbit.

Full reusability will probably never be ideal with an air-launch design, but I guess nothing's stopping you from slapping some heat tiles on the second stage at the expense of some (read: most) of your payload capacity.

Edited August 14, 2014 by Chris P. Bacon

[Nibb31]

Thought I'd leave this here http://www.stratolaunch.com/

The economical viability of Stratolaunch is quite debatable.

Building a one-off aircraft with its specialized support infrastructure is not cheap. Neither is building the support infrastructure for the rocket itself. That plane is going to spend most of its time sitting around waiting for a launch, so maintenance cost is going to be high. A plane sitting in a hangar is a plane losing money. They are going to need frequent flights in order to keep the plane busy and the demand for those frequent flights simply aren't there.

It is still going to carry a conventional expendable rocket, which is going to need its own ground infrastructure, including LOX and LH2 storage and payload processing facility. Also, designing a rocket that is built to support both lateral loads (hanging underneath a plane) as well as longitudinal loads, is going to require reinforcements and extra weight. It seems to have wings too. All of those things cut into the payload fraction.

The only real advantage of Stratolaunch is flexibility, being able to launch regardless of the weather and from a wider variety of locations.

[Chris P. Bacon]

I don't see it as economically viable at all, it seems like a wild pipe dream to me, and the fact that they're out there in the desert building the thing is hilarious. SpaceX with their re-usability was ambitious, and only time will tell if it will pay off over disposable stages, but Stratolaunch just seems ridiculously ambitious. But hey, its their money, best of luck to em'

The only thing I'd argue in that statement are the maintenance costs. Sure its losing money every minute its on the ground, but it's not exactly a commercial airliner, there's a pretty limited market for a craft like that. Plus turbine aircraft are measured in cycles before they need overhauls (how many times you heat-cycle the engines or work harden the airframe by pressurizing it). Aircraft that fly trans-atlantic and trans-pacific routes are incredibly cheaper to maintain compared to regional airliners, while they may have more hours and miles on them, simply for the fact that they only cycle the engines and airframe every day or two. Seems to me maintenance costs wouldn't be that much of an issue on the craft itsself, but the costs to run the facility must be astronomical. It would make more sense to me just to fly to the cape or vandenburg and use their cryogenic fuel facilities.

But yeah, the fact that they're going with liquid fuel seems crazy in my mind. Orbital had it right with the solid-fuel Pegasus, you can launch that thing from anywhere.

Edited August 14, 2014 by Chris P. Bacon

[sojourner]

Stratolaunch will probably make more money renting the plane out to transport rockets from factory to launch site than it will actually flying missions. SpaceX has to get they're BFR to Florida somehow.