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Paul Allen's new rocket-launching plane

arstechnica.com

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Re: Paul Allen's new rocket-launching plane

#131

Post by TeMPOraL »

innergame wrote: post #66

I feel overcome by the Dianne Kruger effect, to an extent I don't remember feeling any time recently. I'm becoming more and more interested in news about rocketry (due to SpaceX of course) but I'm still a full on space-pleb. I see something like this and my intuition screams "Woah! Of course! Why don't other rocket companies do this? What's wrong with them?!" But the rational part of my brain kicks in and slaps me do…

I don't know. Honestly, I feel hit by D-K myself here, because until today I was convinced that launching a rocket from an airplane is a huge expense compared to the very small benefit it can bring. But this thread made me seriously reevaluate this assumption.

The worst thing is, I can't even remember where I have learned that plane-launched rockets make little sense.

Re: Paul Allen's new rocket-launching plane

#132

Post by credit_guy »

mLuby wrote: post #27

IANARS but this plane should give the remaining stage(s) four advantages: 1. +230m/s orbital velocity [1] 2. +9km launch altitude [1] 3. can launch in more weather conditions 4. 1st stage can abort mid-launch without loss of payload. Of these, the most important is the increase in launch altitude, because that means stage 2 launches in air of greatly decreased density, leading to the following efficiencies: A. a vacu…

Avoiding drag could be a huge benefit if you envision an air breathing second stage (ramjet or scramjet).

Re: Paul Allen's new rocket-launching plane

#134

Post by mabbo »

curtis wrote: post #45

It seems like air launch doesn't buy you a whole lot, but it turns out that a small win on delta-v can result in a fairly big win on payload. This might seem counter-intuitive, but you have to remember that in orbital class rockets, payload is only 5% or so of total mass at take-off.

It's a bit like having a very small first stage that gets you out of the thickest air, with a little speed and altitude.

The Falcon 9, by comparison, uses the first stage to get many times higher, but spends a huge amount of it's fuel during that first part of takeoff. For smaller launches, the plane-drop seems a much better idea.

Re: Paul Allen's new rocket-launching plane

#136

Post by rbanffy »

CydeWeys wrote: post #123
schiffern wrote: post #89

Earlier quoted context omitted.

>The 747 engines are probably used. There are lots of retired 747s around, many at the Mojave boneyard. Great aircraft, but a fuel hog by current standards. Correct. They just flew in two used 747s and cannibalized them for parts. http://www.seattletimes.com/business/boeing-aerospace/paul-a... > The crew’s flight deck is literally that of a 747. > Allen bought two used jumbo jets formerly flown by United Airlines and…

That's absolutely how I would've done it. Way cheaper to make a monster hybrid of two used 747s than to try to make a one-off custom airplane from scratch. Sure, it won't be as efficient at its job as if it were purpose-built, but you'd never get all of that R&D money back.

Once the concept is proven, once there is a real market for that, other, more efficient planes designed for bigger rockets will be built.

Re: Paul Allen's new rocket-launching plane

#137

Post by rbanffy »

kashkhan wrote: post #57
monk_e_boy wrote: post #54

Earlier quoted context omitted.

So the bit of wing that joins the two fuselages is made of carbon fibre? Are there any details on how it was constructed? Imagine that thing, fully loaded taking off into turbulent air. Scary.

the plane structure is all carbon/CFRP. you can see in the earlier pictures in the hangar before. http://www.stratolaunch.com/gallery.html the black is cfrp under the white paint. Scaled Composites has some secret CFRP processes of construction which non Americans are not allowed to know about under ITAR regulations, so i cannot tell you haha.

> Scaled Composites has some secret CFRP processes of construction which non Americans are not allowed to know about under ITAR regulations

Everybody knows that. We just don't want you to know we know ;-)

Re: Paul Allen's new rocket-launching plane

#138

Post by mabbo »

ndr wrote: post #2

The article doesn't mention SpaceX, I wonder what's the difference in energy and cost for launching (and landing) the relative stage 1s. Does anyone have an idea on that?

The Falcon 9 first stage releases stage 2 at around 6-10 times the height and 10x the speed.

That said, remember that the difficulty of elevating yourself above a given height is much worse the lower you are. Using a plane-drop means skipping the very worst parts of the launch. The air is so much thinner.

There's other advantages though. Launch windows get much easier, as the plane can fly in any direction, and stay at a given heading a bit longer.

Re: Paul Allen's new rocket-launching plane

#140

Post by OperationHealth »

This is being blown out of proportion. Vulcan's Stratolauncher is not the future of launch; if this thing ever manages to leave the ground (with a payload), I doubt it will host more than five-to-seven launches throughout its lifetime, and that's a generous estimate.

This vehicle is going to be incredibly expensive, compared to both other air launch options and dedicated smallsat options. Although this can change, the current plan is for Stratolaunch to use OATK's Pegasus-XL payload, which provides an indicator for cost. Pegasus-XL launches are incredibly expensive ($337.3K per kg). Now, this is due to a variety of reasons (the L-1011's incredibly high maintenance costs, OATK's expensive labor structure, low launch cadence). Vulcan will bear similar costs--the inefficient OATK overhead tied to Pegasus-XL, Stratolauncher is a one-of-a-kind aircraft and increasing maintenance costs (despite using 747 engines). Due to significant development delays, the company has yet to develop or execute a customer strategy. Depending on how much more PA pumps into it, the company will not be price competitive in the market.

For comparison, other small launchers charge ~$25K/kg-$41K/kg (e.g., Rocket Lab, Virgin, Arianespace), and most of these will be able to launch US payloads. Virgin's comparable airlauncher delivers slightly less mass (15 kg less), but is priced at ~$40K/kg. Virgin is already a leg up as it has engaged commercial, civil govt., and mil-govt. customers.

Lastly, it's worth noting that this vehicle still has significant work to be done--look at the wings in the picture.

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