Space Launch System - Orion
Discussion
Because -
a) limited funds
b) it's not a simple conversion.
Just because they are basing the new rocket on an existing set of technologies does not mean that it is a straightforward bolting together of existing components.
For a start, the External Tank and the Solid Rocket boosters are enlarged versions of what was used on the Shuttle. This means that the structure and the loads it experiences during launch will be very different to a Shuttle launch.
The SLS will use FOUR Space Shuttle Main engines. The Shuttle had three. No one has ever fired four SSMEs together, so that requires a lot of new engineering and testing to make all that work correctly. In addition, the SSMEs are now to be placed directly below the main tank, turning the ET into a rocket in its own right. The SSMEs were originally designed to apply their thrust slightly off centre (they were mounted at an angle on the Orbiter to avoid damage to the Shuttle ET and solid boosters. On SLS they will fire directly downwards - again, this is new and requires a certain amount of simulation and testing.
The SSME s will not be reused on SLS so they have had their thrust rating upgraded to a higher level. This allows the SLS to carry more payload than it otherwise would if they were attempting to recover and reuse the main engines.
a) limited funds
b) it's not a simple conversion.
Just because they are basing the new rocket on an existing set of technologies does not mean that it is a straightforward bolting together of existing components.
For a start, the External Tank and the Solid Rocket boosters are enlarged versions of what was used on the Shuttle. This means that the structure and the loads it experiences during launch will be very different to a Shuttle launch.
The SLS will use FOUR Space Shuttle Main engines. The Shuttle had three. No one has ever fired four SSMEs together, so that requires a lot of new engineering and testing to make all that work correctly. In addition, the SSMEs are now to be placed directly below the main tank, turning the ET into a rocket in its own right. The SSMEs were originally designed to apply their thrust slightly off centre (they were mounted at an angle on the Orbiter to avoid damage to the Shuttle ET and solid boosters. On SLS they will fire directly downwards - again, this is new and requires a certain amount of simulation and testing.
The SSME s will not be reused on SLS so they have had their thrust rating upgraded to a higher level. This allows the SLS to carry more payload than it otherwise would if they were attempting to recover and reuse the main engines.
Eric Mc said:
For a start, the External Tank and the Solid Rocket boosters are enlarged versions of what was used on the Shuttle. This means that the structure and the loads it experiences during launch will be very different to a Shuttle launch.
ExactlyFor example - the Shuttle was mounted to the side of the external tank, with the SSMEs imparting an overall upward thrust from its three attachment points ( two at the base of the tank and one on the intertank ), with SRB thrust loads also being imparted at the base and intertank levels.
With SLS however, while the SRB loads remain similar, the tank structure must now be strong enough to support not only its own mass against the thrust of four SSMEs mounted to its base, but also the mass of the upper stages and payload.
MartG said:
Exactly
For example - the Shuttle was mounted to the side of the external tank, with the SSMEs imparting an overall upward thrust from its three attachment points ( two at the base of the tank and one on the intertank ), with SRB thrust loads also being imparted at the base and intertank levels.
With SLS however, while the SRB loads remain similar, the tank structure must now be strong enough to support not only its own mass against the thrust of four SSMEs mounted to its base, but also the mass of the upper stages and payload.
So it's no longer a tank but a first stage, simples. For example - the Shuttle was mounted to the side of the external tank, with the SSMEs imparting an overall upward thrust from its three attachment points ( two at the base of the tank and one on the intertank ), with SRB thrust loads also being imparted at the base and intertank levels.
With SLS however, while the SRB loads remain similar, the tank structure must now be strong enough to support not only its own mass against the thrust of four SSMEs mounted to its base, but also the mass of the upper stages and payload.
It's not like they are novices at accommodating strap on boosters either it's just that the numbers are bigger.
So throttle engines thrust line is what, on axis? Yes.
So what's new?
The concept is not new. However, the actual hardware that is being used has not been assembled and configured in that exact configuration so that part of it is new. Wiith these triple booster arrangements, estimating the structural and aerodynamic loads is extremely difficult and takes time.
In fact, the concept is PRETTY new in that the other "triple parallel booster" rockets used in the US space programme have been quite different.
The Titan III family used a liquid fueled core with two solid fuel boosters. But its liquid fuels were hypergolic and storable and did not have to be chilled prior to loading.
The Delta IV Heavy has three liquid fuel boosters, all using liquid hydrogen/liquid oxygen
The SLS has a liquid hydrogen/oxygen central core booster with solid rocket boosters
Musk has admitted that the calculating of the loads and stresses on the Falcon 9 Heavy has turned out to be much more difficult than they anticipated
The Falcon 9 heavy uses three boosters all fueled with kerosene and liquid oxygen..
They are all different.
In fact, the concept is PRETTY new in that the other "triple parallel booster" rockets used in the US space programme have been quite different.
The Titan III family used a liquid fueled core with two solid fuel boosters. But its liquid fuels were hypergolic and storable and did not have to be chilled prior to loading.
The Delta IV Heavy has three liquid fuel boosters, all using liquid hydrogen/liquid oxygen
The SLS has a liquid hydrogen/oxygen central core booster with solid rocket boosters
Musk has admitted that the calculating of the loads and stresses on the Falcon 9 Heavy has turned out to be much more difficult than they anticipated
The Falcon 9 heavy uses three boosters all fueled with kerosene and liquid oxygen..
They are all different.
Eric Mc said:
The Falcon 9 heavy uses three boosters all fueled with kerosene and liquid oxygen..
Later versions of F9H may also use 'asparagus' staging, where the core stage initially uses propellants fed from the boosters, so at the time boosters separate the core stage is still full
The often use asymmetrical solid rocket booster arrangements on the Atlas V.
This one launched the OSIRIS-REx probe last year:
https://www.youtube.com/watch?v=D2df1EXa910
It looks like it's crabbing into the sky. But fly it does. The wonders of steerable nozzles.
This Atlas V was in the 411 configuration: 4 meter fairing, 1 solid rocket booster, 1 engine on the second stage.
This one launched the OSIRIS-REx probe last year:
https://www.youtube.com/watch?v=D2df1EXa910
It looks like it's crabbing into the sky. But fly it does. The wonders of steerable nozzles.
This Atlas V was in the 411 configuration: 4 meter fairing, 1 solid rocket booster, 1 engine on the second stage.
http://www.dynetics.com/news/497
I guess this is the equivalent of Saturn V 500-F which was used to check compatibility with the launch pad and other ground equipment
They completed the summer's final test of one of the RS-25 engines earlier today.
https://www.youtube.com/watch?v=g5BvriNNb64
Next step is to fire all 4 together.
https://www.youtube.com/watch?v=g5BvriNNb64
Next step is to fire all 4 together.
Gassing Station | Science! | Top of Page | What's New | My Stuff