Virgin Orbit's First Orbital Test Flight Cut Short After Rocket Released from Carrier Aircraft (techcrunch.com) 40
An anonymous reader shares a report: On Monday, Virgin Orbit attempted the first full flight of its orbital payload launch system, which includes a modified Boeing 747 called 'Cosmic Girl' that acts as a carrier aircraft for its air-launched rocket LauncherOne. While Virgin Orbit has flown Cosmic Girl and LauncherOne previously for different tests and demonstrations, this was the first end-to-end system test. Unfortunately, that test ended much earlier than planned -- just shortly after the LauncherOne rocket was released from Cosmic Girl. Cosmic Girl took off just before 12 PM PT (3 PM ET) from Mojave Air and Spaceport in California. The aircraft was piloted by Chief Test Pilot Kelly Latimer, along with her co-pilot Todd Ericson. The aircraft then flew to its target release point, where LauncherOne did manage a "clean release" from the carrier craft as planned at around 12:50 PM PT (3:50 PM ET), but Virgin noted just a few minutes later that the mission was subsequently "terminated."
What is the point of air-launched orbital rockets? (Score:1)
Re: What is the point of air-launched orbital rock (Score:5, Informative)
You would actually be surprised at the reality of the situation. First thing that comes to mind is the expansion ratio of the exhaust nozzle in terms of efficiency. Getting the rocket into low density atmosphere, even if you have zero velocity, helps a lot in terms of having a nozzle that's efficient throughout the flight profile.
Re: What is the point of air-launched orbital roc (Score:5, Informative)
That's why they're working on an aerospike engine. But they haven't yet gotten a practical, reliable design yet.
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There were working aerospike engines built. They were not more efficient. That's why no one serious is working on them now.
The important thing for modern rocketry is that they seem very hard to make reusable, and non-reusable rockets are a relic of the 20th century.
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Here's the problem with aerospikes [youtube.com].
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That's the point. You can't say definitively that aerospikes will never be a good choice. But they have some fundamental problems - as laid out in that video, such as the cooling problem - which have so far repeatedly led to the abandonment of aerospike designs, even though people keep trying.
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If you post your address here we'll drop by tonight for a chat (around 2am is OK for you?)
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That has nearly nothing to do with it, and launching from these altitudes and speeds are a marginal effect on the delta-V required.
The perceived advantage is flexibility, you can fly the airplane to put the orbit where you need it, any time on any day, and not have to wait for the orbit plane to rotate to the (fixed) launch site.
It is highly dubious whether the compromises required are worth it, and several previous air-launch systems have already come and gone f
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Besides the flexibility of launch is the flexibility of being able to land anywhere and the ferry craft comes to pick the spacecraft up. You also only need one servicing facility for refurb between flights, whereas if you're launching into multiple orbits with any other reusable spacecraft you would need a servicing facility at each launch site.
Still not terribly impressed with Virgin, though. Their progress seems snail-like.
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LauncherOne is an expendable launch vehicle. There's no spacecraft landing anywhere here. If you're thinking of SpaceShipTwo, it's an 80 km vertical joyride that has nothing to do with reaching orbit, or any destination other than the airport it operates from.
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Expendable? Never mind, then. Obviously I didn't RTFA.
Re: What is the point of air-launched orbital rock (Score:4, Interesting)
As your exhaust expands its pressure drops. If the pressure drops to far below the air pressure around it things get unstable. So if you launch from sea level you have to have a higher exhaust pressure and can't have your exhaust expand to its full potential so its velocity is not the maximum. Your rocket equation is exponential so a small decrease in exhaust velocity hurts a lot.
Less atmosphere to push through and launch location flexibility are really minor compared to the gain in effective exhaust velocity.
Thanks. I was wondering last night (Score:2)
It's kinda strange, last night before bed I started wondering how air launch really helps for orbital craft. When you need an orbital velocity of around 28,000 km/h, the 900 km/h of a 747 doesn't seem to make enough difference to bother with everything needed for air launch.
Funny I fell asleep wondering about that and woke up to a Slashdot story with your answer to the question.
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lowest possible orbit is 170km, 10km advantage is a huge, especially when horizontal speed is already 500 km/h and rocket can use vacuum engine to reach orbit instead of sea-level and vacuum engine combinations.
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500 km/h is a tiny fraction of the required 28,000 km/h to reach orbit, and an extra 10 km of climbing is a non-issue next to that.
There's some merit to the idea of using vacuum-optimised engines to take advantage of the lower air pressure at 10km altitude, but they're apparently not doing that. It's still a two stage vehicle with different engines [wikipedia.org] for each, with the second-stage NewtonFour engine designed for multiple restarts in vacuum.
Re:What is the point of air-launched orbital rocke (Score:5, Interesting)
Yeah. Naive calculations show you save 3-4% of your orbital energy requirements with subsonic air launch. In practice it's more than that because of avoiding the need to plow through the densest part of the atmosphere and avoiding the need to start with less efficient sea level nozzles. But it's still not a ton.** The big thing it does for you is logistics - you can launch from all over the world, without needing a pad, no noise limits beyond that of a conventional airport, etc.
Even if it's good for small rockets, air launch doesn't scale. The heaviest payload ever lifted by an airplane (an An-225) was just a third the mass of a fueled Falcon 9, for example.
** - Depending on the design, you might - or might not - also be able to save some rocket mass. Long ago, in the Before Time, I was toying with a tow-launched HTOL rocket with propellant feeds paired with the tow cable, and propellant tanks and pumps in the tow plane. The reason being that the landing gear and mount requirements for a fully fueled HTOL craft are far heavier than what you need for an empty craft (and they come in for landing empty or near-empty), so with midair prop loading you could meaningfully lighten the spacecraft. It of course increases the mass of the tow craft (for a given size launch vehicle), but your ISP on an airbreathing tow craft is massive. Also, with tow launch, you don't have to deal with any of the awkward problems that are associated with under-wing, under-fuselage, or inside-fuselage launches. You can use a practically stock, near-end-of-service cargo jet (near-end-of-service because you don't need to get a lot of low-turnaround flights out of it).
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Aerodynamic drag is only significant for the smallest of launchers (which are also the only ones you can fit on a carrier aircraft). The Saturn V only lost 40 m/s of delta-v to aerodynamic drag. You can achieve the same performance benefit as air launch by just making the rocket a few percent bigger.
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Two obvious benefits come to mind:
1) At a higher altitude, the nozzle can have a different profile that is somewhat closer to vacuum conditions. Such a nozzle needn't even survive ground start. Because even first stages spend significant amounts of time outside of dense atmosphere, this optimizes performance.
2) With a horizontal air launch, you needn't go for a 1.2-2 thrust-to-weight ratio just to lift off. You can start even somewhat below 1, so the same engine can be used for a heavier vehicle, or, the sa
Re:What is the point of air-launched orbital rocke (Score:5, Informative)
1. You can launch from almost anywhere that a 747 can take off
2. You can hit virtually any orbit, at any inclination, as the angle of launch is not restricted by your site.
The military have already showed a lot of interest in this configuration, because of its high flexibility more than efficiency or cost.
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You can launch from almost anywhere that a 747 can take off
You can place a whole ounce of weed into orbit!
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You can place a whole ounce of weed into orbit!
Cheech, the van worked so well, let's build a weed rocket.
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One advantage I've seen mentioned is that since the aircraft is essentially a mobile launchpad, that allows you to take off from any airport that can support an aircraft of that size, and then fly to a location that best fits the required orbit, rather than be limited to a few pre-built launch sites.
Northrop Grumman is doing it for +30 years (Score:2)
So there must be some benefit to it.
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NG offers one of the most expensive launchers on the market (a Pegasus launch is in the region of $40M), so their number of annual launches has been tiny for the last several years. Virgin's price is 1/4 of that.
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The ICON satellite was likely the last launch Pegasus will ever do. It was delayed years due to launcher issues, and cost more than next year's IXPE launch on a Falcon 9. Efficiency advantages are a bit moot when a vehicle with ~40 times the payload capacity is cheaper to launch...Falcon 9 has an abundance of excess performance to use to compensate for its suboptimal launch site for the target orbit.
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I never understood the benefits of launching an orbital rocket from an aircraft. Both the kinetic and the potential energy received by this initial push is just a small fraction of what is needed to get to LEO.
What fraction, exactly? (citation needed)
I'm betting that if they go the expense of a custom 747 then it's not a small number.
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The exponential nature of the rocket equation means almost any reusable component is good. Plus free choice of orbits plus optimizing for thinner athmosphere means that even if an airplane can't get you very far, it still seemed worth doing. But now that we know that the entire first stage can land and be reused, going much higher and faster it seems like an inferior solution. But until there's a small scale rocket doing what SpaceX does - if the solution actually scales down - I guess it'll have a market.
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TWR (Score:1)
Any horoscope news? (Score:2)
I like this new turn in /. !
Leadership counts (Score:4, Insightful)
Books will be written about the "billionaire space race" we are currently seeing but it has to be said that like him or not Musks leadership and commitment really make a difference in results so far with the 3 companies: Virgin galactic founded 2004, Blue Origin founded 2000, SpaceX founded 2002. Musk is rich but not nearly on the scale as Bezos and Branson, especially in the early 2000's and yet here we are with SpaceX about to return astronauts to space and the only company to have even reached orbit. At this rate SpaceX could even be the first to have space tourism despite that being the primary current goal of VO and BO.
BO and Virgin certainly cannot say it's lack of talent, they have several industry veterans and large teams but it's plain to see those moguls only have so much involvement in their space ventures beyond funding. Musk is an asshole but with him hands on with his teams involvement he has really pushed the needle to where honestly the other 2 should feel a bit embarrassed. Goes to show that having hands on dedication from the top down will get far better results than just hiring out a team, shoving them some money and let them figure it out from there. Even if he is an unrepentant jerk the guy has vision.
Re:Leadership counts (Score:4)
Every CEO on the planet justifies their obscene salary by claiming that they provide "leadership", and apparently most of them truly believe that without them at the helm no one would bother to show up for work or be inspired to perform. Musk appears to be one of the few who actually accomplish that goal, putting him in a rather limited club with Gates, Jobs, and a very few others.
What an Odd Time to Terminate the Mission (Score:1)
Why can't companies just admin that they didn't get the job done perfectly on the first try? Based on the wording of their statement, they made it seem like the engineers just got bored during the mission and decided to leave the control center to play Fortnite instead. For all of Elon Musk's faults, at least he's usually upfron