Why do we still expect “successful failures” on rocket launches and not just scale up or scale down the same design on successful rocket ships and launch pads to make bigger or smaller ships with more stable structural material?
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I dont think they expected it to happen, I think they knew it had a chance of happening though
I dont think they expected it to happen, I think they knew it had a chance of happening though
Scaling something up or down doesnt work that way, because as somethings size increases, its weight increases even more.
Scaling something up or down doesnt work that way, because as somethings size increases, its weight increases even more.
If you double a rocket’s height (see edit), then the area of things goes up by 2^2 = 4 and its volume goes up by 2^3 = 8. Significantly it’s weight (which is a function of volume) goes up by 8, but the amount of fuel which goes through a pipe (which is a function of the cross section area of the pipe) only goes up by 4. So you’d need to increase the speed the fuel is moving, which requires a stronger pump and higher pressure in the pipe which means…
And there are countless other systems which have similar problems being scaled up. At some point you need to build the thing full size and test it.
Edit: as well as doubling the height, you do, of course, also need to double the other dimensions (radius or depth and width) which would keep it a scale model as OP was asking about.
This concept is known as the square/cube law.
If you double a rocket’s height (see edit), then the area of things goes up by 2^2 = 4 and its volume goes up by 2^3 = 8. Significantly it’s weight (which is a function of volume) goes up by 8, but the amount of fuel which goes through a pipe (which is a function of the cross section area of the pipe) only goes up by 4. So you’d need to increase the speed the fuel is moving, which requires a stronger pump and higher pressure in the pipe which means…
And there are countless other systems which have similar problems being scaled up. At some point you need to build the thing full size and test it.
Edit: as well as doubling the height, you do, of course, also need to double the other dimensions (radius or depth and width) which would keep it a scale model as OP was asking about.
This concept is known as the square/cube law.
> Why do we still expect “successful failures”
That’s just one of Elon Musk’s marketing gimmicks. They did not expect or want the launch to fail.
> and not just scale up or scale down the same design on successful rocket ships and launch pads to make bigger or smaller ships with more stable structural material
Fluid mechanics is highly nonlinear. If you simply scale a system involving fluids up or down, it won’t necessarily behave in the same way. The things you want from space launches also aren’t the same every time. Different kinds of satellites and spacecraft need to be launched into different kinds of orbits, and the payloads vary in terms of size, fragility, and mass distribution.
But the basic problems are that (1) the speed and power that need to be achieved during launches just inherently lead to risks, as they put the components under so much stress and there is very little time to react if anything goes wrong, and (2) space launches are still a relatively niche activity – it’s not like planes, where there are many thousands of flights every day and just about everything that can go wrong has already gone wrong multiple times and been learned from.
There are also various political issues. There are many countries and businesses that work on spaceflight, and to some extent they cooperate with each other but to some extent they compete with each other, leading to all kinds of awkwardness. Because it’s so politically charged, there are many constraints they have to work under. They can’t share this technology with people from that country, they have to build part of the rocket in this state because an influential politician demanded it, they have to contract part of it out to a particular country because of a treaty signed 20 years ago, etc. And instead of doing something worthwhile, they have to send people to the Moon again because that leads to exciting TV footage, and voters like exciting TV footage more than boring scientific papers. It also does not help that one of the leading space companies is led by a profoundly stupid man who thinks he is the world’s greatest engineer ever since he happened to invest Daddy’s money in Paypal at just the right time.
> Why do we still expect “successful failures”
That’s just one of Elon Musk’s marketing gimmicks. They did not expect or want the launch to fail.
> and not just scale up or scale down the same design on successful rocket ships and launch pads to make bigger or smaller ships with more stable structural material
Fluid mechanics is highly nonlinear. If you simply scale a system involving fluids up or down, it won’t necessarily behave in the same way. The things you want from space launches also aren’t the same every time. Different kinds of satellites and spacecraft need to be launched into different kinds of orbits, and the payloads vary in terms of size, fragility, and mass distribution.
But the basic problems are that (1) the speed and power that need to be achieved during launches just inherently lead to risks, as they put the components under so much stress and there is very little time to react if anything goes wrong, and (2) space launches are still a relatively niche activity – it’s not like planes, where there are many thousands of flights every day and just about everything that can go wrong has already gone wrong multiple times and been learned from.
There are also various political issues. There are many countries and businesses that work on spaceflight, and to some extent they cooperate with each other but to some extent they compete with each other, leading to all kinds of awkwardness. Because it’s so politically charged, there are many constraints they have to work under. They can’t share this technology with people from that country, they have to build part of the rocket in this state because an influential politician demanded it, they have to contract part of it out to a particular country because of a treaty signed 20 years ago, etc. And instead of doing something worthwhile, they have to send people to the Moon again because that leads to exciting TV footage, and voters like exciting TV footage more than boring scientific papers. It also does not help that one of the leading space companies is led by a profoundly stupid man who thinks he is the world’s greatest engineer ever since he happened to invest Daddy’s money in Paypal at just the right time.
Because square-cube law.
Weight increases cubic to dimensions, while material cross section that gives the strenght to things only grows quadratic. So do many values. Many do square and many do cube up.
As a general rule, the bigger you go:
-the easier to achieve speeds, long ranges, big payload.
-The harder it is to achieve structural strenght, rigidity, agility, accelerations.
If you scale up a mosquito it won’t work. If you scale down an airliner it won’t work.
Because square-cube law.
Weight increases cubic to dimensions, while material cross section that gives the strenght to things only grows quadratic. So do many values. Many do square and many do cube up.
As a general rule, the bigger you go:
-the easier to achieve speeds, long ranges, big payload.
-The harder it is to achieve structural strenght, rigidity, agility, accelerations.
If you scale up a mosquito it won’t work. If you scale down an airliner it won’t work.
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