Comments by "Tony Wilson" (@tonywilson4713) on "Why Virgin Orbit Failed" video.

  1. Also on air launching (and yes I have a degree in aerospace) its NOT just the saving on delta-v. They are only launching from around 10km at less at about 0.25km/s, while orbit is over 200km and over 7km/s. So the actual height and speed gains have little to do with anything. The actual advantages of air launching and they are incremental buy do add up. 1) You don't need to build a dedicated launch facility. All that is needed is a hanger and a convenient airfield. That's a cost saving. 2) Air launching includes a fully reusable first stage. That's a cost saving. 3) It can launch "on orbit" or closer to orbit. All normal launches require fuel in the upper stage to get from the launch sites global position over onto the global orbital position. Reducing the amount of fuel needed either lowers costs or allows for larger payloads. Where I think they didn't learn from previous systems. 1) Launcher 1 is significantly heavier 30t than Pegasus XL 23t which was a fair step of from Pegasus 18.5t. When you are staring with a vehicle around 50% bigger than your competitor and you have all the development hassle a smaller system would have been a lot smarter to start with and then build up from there. Starting out with something much smaller would have meant debugging all their systems both in the vehicle and in the manufacturing and launch processes with a cheaper vehicle and fewer people. They forgot that whole learning to walk before learning to run thing. 2) That extra weight meant a bigger more costly aircraft. Maybe the surplus 747s were cheaper to buy but a smaller 767 can lift those sorts of loads and with only 2 engines to service is a huge operational cost saving. Remember Pegasus used a modified L-1011 Tristar for most of its life. Every time a 747 flies compared to something like a 737 or 767 that's a lot of fuel burn and a lot of maintenance. This is a lesson everyone should have got from the Space Shuttle. Every launch of the Space shuttle meant putting 75tons into orbit before you did anything else. That's a lot of unnecessary cost and also why the ISS cost so much and why Crew Dragon is a massive step in the right direction. AND NO I am not an Elon Musk fanbot but I do cut him some slack on Space-X. 3) Their flight profile negated a very important aspect of what they learned with Pegasus. The wing on Pegasus allowed the vehicle to gain a lot of speed in horizontal flight at a point which is significantly more fuel efficient than trying to accelerate in vertical flight because there is still air drag at that point. That might not be a lot of difference but Pegasus works and Launcher One doesn't. 4) The most important thing they forgot is that space flight is hard and no matter how much money you have their will be failures. Go and look at the Pegasus launch list. They had 4 failures (or partial failures) in the first 10 launches, another at 14 and then 31 successful launches in a row. This stuff is hard and all the vehicles are built right on the razor's edge of failure.
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  2. That has nothing to do with overall operations. Michael Sheetz (CNBC) sums it up best right near the end of the video. "Virgin Orbit's legacy within the space industry is a story that's too often told where there are exciting or even innovative new technologies. But that does not make necessarily for a smart or financially sound business." That's not just true of space but the wider technology sphere. Look at how many wonder technologies have been in the news over the last 25 years and nothing come from any of them. There's a meme that "99% of general startups fail." If there was a meme for aerospace it would be "99.9% of aerospace startups fail while the other .1% has juicy military contracts for stuff that doesn't work."
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  3. ​ @qownson4410  You're very much on the right thinking process but you're simply not going to air launch at 70,000-100,000 feet because there's so few jets capable of that high . But you are quite right that getting as as hight is is an important part of the discussion. Sorry if this is a long comment. I actually put in a A$720 Million proposal to the Australian government based around air launching. So I did a lot of research into this subject a few years ago. The carrier aircraft I proposed was a 2nd Gen White Knight One as used to carry Spaceship One that won the X-Prize. There's a really interesting item about White Knight One. It uses the same engines as the T-38 Talon (General Electric J85) which is the military version of the General Electric CJ610 engine used in the early Learjets (23, 24, 25 & 28). What many people don't realise is that the Learjet was originally proposed as a small tactical bomber and as such had military grade engines. So White Knight One like those early Learjets could fly up to 53,000 ft which is substantially higher than the normal 35-45,000 ft limits we see with current commercial aircraft. That 10,000 ft doesn't sound much but its significant because of where it is in the flight profile. If you had unlimited access to ex-military aircraft the Convair B-58 Hustler is the plane to consider because it could not only go high (63,000ft) but also very fast (Mach 2 at 40,000ft). Going back to why that extra altitude matters. Its simple high school level science. Getting into space is all about energy and there's 2 parts to that. Straight out altitude is the potential energy equation pe = mgh. Getting into orbit requires speed and that means kinetic energy ke = 1/2mv². So no matter the launch type every bit of altitude and speed you can get matters and saving fuel matters because that's your energy source. This is as Don Pettit put it "The Tyranny of the Rocket Equation" https://www.youtube.com/watch?v=uWjdnvYok4I Air launching has the obvious saving that you are launching at speed and altitude. You simply avoid all the issues of the launch pad. That's when a rocket is at its least efficient because that's when its total mass is highest and the rocket nozzle needs to produce its highest thrust. Where air launching also saves fuel however is at the top of the launch profile. If you launch from a fixed location you have to burn fuel right at the top of the profile to get onto the desired orbit. This is the part of the launch sometimes referred to as "orbital insertion." You have to burn fuel getting onto the right trajectory. Air launching reduces the amount of fuel needed for that because at the moment you launch you are pointing in the right direction. Its sometimes referred to as "launching on orbit." So there's substantial fuel savings from air launching. At times its not that much and at other times its more. Irrespective every extra kilo you can lift is a bonus. That's even more significant if your payload has orbital adjustment motors because you end up with more useable fuel on the payload. The other consideration is construction of facilities. All you need for air launching is a hangar beside the runway. You don't need launch platforms or towers or spend money maintaining them or much else other than a convenient airport. People tend to forget those costs all add up. Again - sorry for the long comment but you are on the right thought process.
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  4.  @vasopel  Thanks. Its kinda frustrating with the media these days. Unfortunately they all think being able to use a computer makes them technically literate. Its not just aerospace its pretty much everything technical.
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  5.  @bentucker7280  You're right and that's just another of the advantages of air launching. The only real problem is that that there is a practical size limit and I think that's part of Launcher Ones issues. Its almost 50% heavier than Pegasus XL which is a fairly big. A Tomahawk extended range cruise missile and AGM 129 are both around 1.6 tons Pegasus XL is 23.1t Launcher One is around 30t That's a lot of mass to be holding in the way air launched rockets are launched.
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  6.  @trouty7947  Yep I know all those points well. For rockets up to a certain size (and I think Pegasus XL is close to the limit and Launcher One is past the limit) there is nothing better than air launching. Smaller rockets are less efficient in terms of payload than larger ones because not everything scales down. So getting some of that back by launching at 40-50,000 ft and needing less fuel to get onto the right orbital track is a big deal. Plus not having to build launch facilities saves millions that can go into jet fuel and rocket fuel.
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  7.  @h8GW  NO - other direction. They would have been far better off starting with a smaller rocket on a smaller jet and then building up. The single biggest cost in flying jets (after the fuel) is the engine maintenance. Its why twin engine jets have become the main stay of the air industry. Go back to the 70s and 80s and there were lots of triple engine jets like the L-1011 and DC-10, 727 and they have all gone the way of the dodo. The cost savings on engine maintenance is huge.
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