http://www.businessinsider.com/generation-rent-londoners-spend-40-of-income-on-rent-says-ifs-2017-10
I'm particularly intrigued about Chart 1, which to paraphrase the article, argues that
" A new IFS report found the rent-to-income ratio in Britain excluding London has fallen by 3% — from 31% to 28% — in the last twenty years, but climbed by 3% — from 37% to 40% — in London over the same period.
It seems that ignoring London, the median percentage of income spent on rent among private renters is now lower than it was in the 1990s, and it's close to the 2000's.
]]>Here are the comparisons
Delta IV: 35 Pegasus XL: 43 Atlas V: 73 Atlas II: 63 Ariane V: 93 Delta II: 153 Ariane IV: 116
I realize that I'm not taking the timeline into account: most of those rockets have existed for much longer than Falcon 9. For instance, I realize that the Delta II was the workhorse for decades.
]]>In the 60s for many of them it was the offer of 50% or more money being offered by NASA compared to the steel plant or electric motor factory.
]]>They were not optimized for low cost to orbit but to get away from the launch site and air just above it as fast as possible. So they had a lot of intricate machining to make their exterior walls strong and light by machining out the walls to leave behind trusses for strength to deal with the rapid launch stresses. In many ways cost was no object unless totally off the wall obscene. And maybe not even then.
SpaceX and it kin are designed from scratch for cost to orbit. And back. So what if they take 3 times as long to get to 10,000 feet. There's no need to worry about a nuclear weapon going off nearby.
]]>what is NOW ULA rockets
]]>Rocket engineers don't think that's a good idea. Spending more time to get to altitude and orbit means burning more fuel to fight the 9.86 m/s/s pulling the rocket back down to Earth for most of the trajectory. High acceleration from a light rocket saves fuel and oxidiser which can be traded off for a greater payload with the caveat that the light structure has to be able to cope with the high acceleration.
]]>Yes, but as some people have finally noticed, fuel is dirt cheap compared to the price of a potentially-reusable rocket. IIRC the figure for a SpaceX Falcon 9 launch is that about $250,000 goes on fuel; the rest of the double-digit millions goes on rockets and ground support infrastructure.
Doubling or tripling your spend on fuel is money well spent—in fact, a no-brainer—if it buys you the ability to retrieve and reuse your first stage. (And do I need to remind you that SpaceX's launch/retrieval on Tuesday was the second flight of the first stage on that mission?)
]]>And even if not reusable. ULA just blew it by not spending a couple of decades working on a new cheaper model that ignore the requirement of a system designed to be launched before a nuclear warhead went off nearby. Now they are stuck way behind the curve.
]]>I saw an interview with Musk many years ago. He basically said the same thing. Existing rocket manufacture takes huge amounts of the most expensive alloy, manufactured and tested to the most exacting specifications, and then puts 99% of the material in the bin.
He was saying that by changing to additive rather than subtractive manufacture he should be able to save 99% of the cost of manufacture, but that he was targeting 90%.
I don't know how close he's come to that, but when he makes anything, the first thing he does is work out the cost of all the materials in the finished product, Y kg of Carbon Fibre at X dollars per kg... etc. That becomes his floor cost of manufacture, then he works out what the absolute least it cost to get all those materials into the right shape and stuck together. Like "there's 500 000 dollars worth of materials in a rocket, but they cost 80 million dollars to build... If anyone else figured out how to make it for 79 million, they'd be "Yay, I've saved a million dollars!" he's more "Well, I'm still wasting 78 and a half million dollars"
]]>So what if you use twice the fuel. So the fuel costs go from $250K to $500K. If the cost of the booster and engine come down by a million or 5 it's a total win if at the end of the day you're putting a similar mass/weight into orbit.
Again, my point was that for ICBM launches a very major goal is for a 10 minute or less window from command to launch to being miles from the site. That is what drives much of the design of the main booster of an ICBM.
For a commercial launch vehicle the main objective is cost to orbit. Rarely, if ever, does it matter how quickly you clear the pad or how many orbits (within reason) to get to the desired point. So with a totally different set of design goals you come out with a different booster design where those points and others are a derivative of the main objective. Fuel used is one of these items because currently the available fuel supply is somewhat infinite and low cost.
]]>Yep. There are just dozens of conflicting goals here. One group wants a way to deliver a big bang to somewhere else on the planet on little notice but with a "be prepared to go" for years. The other wants to put mass into orbit (typically) around the earth with long lead times and dates of varrying flexibility. While the devices that meet those goals may intersect at times depending on various constraints, there's no rule in physics that says what is best for one is best for the other.
Way too many variables in that equation when solving for "best".
]]>As an extreme case imagine a rocket that took ten minutes to get to 10,000 feet. How much fuel would it have to carry? The fat pig of the Space Race, the Saturn V took 45 seconds of burning 10 tonnes of fuel and oxidiser a second to get to 3km altitude. The Shuttle, less than 30 seconds. A Falcon 9 (depending on payload) will be in the same ballpark.
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