Do y'all think the Space-X Super heavy/Star ship would work out?

[YNM]

3 hours ago, magnemoe said:

Airplanes on the other hand are supposed to be safe.

Why shouldn't mass space travel ?

[kerbiloid]

Maybe because the max fuel pressure in GE-90 turbojet is ~5 atm
https://www.easa.europa.eu/sites/default/files/dfu/EASA TCDS IM E 002_GE90 series_Issue3_15112017.pdf
(IV.4)

, while a rocket engine typically withstands several hundreds?

[Flying dutchman]

11 minutes ago, kerbiloid said:

Maybe because the max fuel pressure in GE-90 turbojet is ~5 atm
https://www.easa.europa.eu/sites/default/files/dfu/EASA TCDS IM E 002_GE90 series_Issue3_15112017.pdf
(IV.4)

, while a rocket engine typically withstands several hundreds?

Well yes, but the fuel injection system of a modern diesel engine easily gets up to several hundred bar aswel. And as far as i know those are pretty reliable.

[kerbiloid]

1 minute ago, Flying dutchman said:

Well yes, but the fuel injection system of a modern diesel engine easily gets up to several hundred bar aswel.

But not for a barrel of fuel per second.

[magnemoe]

5 hours ago, YNM said:

Why shouldn't mass space travel ?

First the energy and stress levels involved is way higher. just the g force is something you only get in fighter jets and they have ejection seats. 
Engine pressure and reentry is problably even larger issues. 
Last is that we have far more experience with planes than rockets both in time and most of all hour flown and planes used. 

Yes starship looks pretty safe, lots of engines so some can fail, the new heat shield is stated to be able to survive reentry without cooling but that will damage it.
That its reuseable also help, that way stupid mistakes will not bring it down. 
Only downside that for abort modes its far closer to the shuttle than dragon 2 or Soyuz  

[YNM]

@magnemoe@kerbiloid So you accept that when space travel becomes common we will have loads and loads of deaths from it ?

Today's small but high-bypass turbofans aren't without their problems - they're run at temperatures well past the softening point of the materials - but we've tested them over and over again for thousands of times without failure before we can put them on use, and even then the slightest of problems in later day can cause full replacement, recalls, and groundings.

I'm not suggesting that we wouldn't become more knowledgeable on rocketry - but getting the levels to down in the mud is a challenge.

And before we can get them down in the mud, LES exists. When you don't have them, Shuttle happens.

[Flying dutchman]

1 hour ago, kerbiloid said:

But not for a barrel of fuel per second.

True but you only refered to the pressure not the flow rate.

[kerbiloid]

32 minutes ago, Flying dutchman said:

True but you only refered to the pressure not the flow rate.

Flow rate / engine own mass is rather different. You can't make a rocket engine as heavy (per fuel flow rate) as a car engine.
So, the rocket engine is much closer to the safety margins.
And it needs thin and lightweight structures to be supported.

So, the car may have a much greater safety factor.

1 hour ago, YNM said:

So you accept that when space travel becomes common we will have loads and loads of deaths from it ?

I have a feeling that the space travel becomes common decades later, at another TechLevel.
So, it's like comparing a plane of Wright Bros to a Boeing.

1 hour ago, YNM said:

Today's small but high-bypass turbofans aren't without their problems - they're run at temperatures well past the softening point of the materials

They still keep the temperature below the softening point of their particular details, as well as rockets do.
But they also work at much lower pressures and don't use cryogenic lines, fuel cooling of nozzles, etc.

1 hour ago, YNM said:

And before we can get them down in the mud, LES exists.

When your crew is trained to withstand extreme overloads.

Spoiler

 

And even then...

Spoiler

 

At that's just 9g. While LES usually makes 12..20+ g to escape from the fireball and from the mad rocket.

A random untrained tourist will be unhappy if he needs to repair his spine and brain after an entertainment flight.
So, LES is unlikely an option. A ship should be as safe as an airliner.
No need to have a million of flights, but you should be sure that the spaceplane details don't change more than the airliner's details do, after every flight.
 

Edited March 20, 2019 by kerbiloid

[YNM]

17 minutes ago, kerbiloid said:

I have a feeling that the space travel becomes common decades later, at another TechLevel.
So, it's like comparing a plane of Wright Bros to a Boeing.

I would agree.

But I hope this keeps everyone realistic about the expectations of what BFR/Starship can be.

[magnemoe]

2 hours ago, YNM said:

@magnemoe@kerbiloid So you accept that when space travel becomes common we will have loads and loads of deaths from it ?

Today's small but high-bypass turbofans aren't without their problems - they're run at temperatures well past the softening point of the materials - but we've tested them over and over again for thousands of times without failure before we can put them on use, and even then the slightest of problems in later day can cause full replacement, recalls, and groundings.

I'm not suggesting that we wouldn't become more knowledgeable on rocketry - but getting the levels to down in the mud is a challenge.

And before we can get them down in the mud, LES exists. When you don't have them, Shuttle happens.

Have some 1000 more launches and you have worked out most of the kinks. Still be more dangerous than planes because of more energy and stress in an rocket launch and reentry. 
 

[Xd the great]

45 minutes ago, YNM said:

I would agree.

But I hope this keeps everyone realistic about the expectations of what BFR/Starship can be.

Realistically, I believe space tourism will become an extreme sport, like driving racecars.

[YNM]

1 hour ago, magnemoe said:

Have some 1000 more launches and you have worked out most of the kinks. Still be more dangerous than planes because of more energy and stress in an rocket launch and reentry. 

Well, most humans are irrational when it comes to probabilities, as always. So we'll have to follow that.

It's alright...

Edited March 20, 2019 by YNM

[Silavite]

13 hours ago, kerbiloid said:

When your crew is trained to withstand extreme overloads.

  Reveal hidden contents

 

And even then...

  Reveal hidden contents

 

At that's just 9g. While LES usually makes 12..20+ g to escape from the fireball and from the mad rocket.

In aircraft, g loads are directed from head to foot. With astronauts seated in couches, they are directed from chest to back. The human body has a much greater tolerance for the latter.

Edited March 20, 2019 by Silavite
Original version of the image linked was almost unreadably small