842
edits
Space Shuttle: Difference between revisions
Jump to navigation
Jump to search
m
→The mated launch vehicle
| Line 63: | Line 63: | ||
The SRBs are implemented as ballistic submodels, i.e. they follow a correct trajectory and ascent with the shuttle, however since (unlike the shuttle) they are not accelerating, they visually fall behind quite quickly. | The SRBs are implemented as ballistic submodels, i.e. they follow a correct trajectory and ascent with the shuttle, however since (unlike the shuttle) they are not accelerating, they visually fall behind quite quickly. | ||
=== The Main Engines === | === The Main Engines === | ||
| Line 95: | Line 98: | ||
In general though, aerodynamical effects are subleading, the ascent dynamics is dominated by the thruster forces and the flight control systems have a large margin to compensate for them. | In general though, aerodynamical effects are subleading, the ascent dynamics is dominated by the thruster forces and the flight control systems have a large margin to compensate for them. | ||
=== The Ascent Performance === | |||
Space Shuttle Main Engine thrust,[https://en.wikipedia.org/wiki/Specific_impulse ISP] , and consumption is now within a percent of the real datas (Dev version of December 2020) | |||
The mixture ratio in real was around 6, and it is what we observe in the sim (6 times more liquid Oxygen burnt than liquid Hydrogen). Hence, Main Engine Cut Off ( MECO) time is matching real one. Plus, the propellant remaining at MECO, called the Final Performance Reserve (FPR) is now within a percent ( 15000 pounds). It makes launch with high payload into a high inclination Orbit (towards ISS typically) really interesting and limitating performance wise, like in real. | |||
An interesting read about that FPR, written by a former Shuttle Flight Controller: [https://waynehale.wordpress.com/2014/10/08/understanding-sts-93-the-key-is-mixture-ratio/ Wayne Hale: The key is Mixture Ratio] | |||
You can find below some in sim datas compared to real one coming from the Shuttle Crew Operations Manual (SCOM). | |||
[[http://wiki.flightgear.org/File:Stage_1_in_sim.png Velocity Vs Time in Sim] [[http://wiki.flightgear.org/File:Stage_1_scom.jpg Velocity Vs Time in real]] | |||
[[http://wiki.flightgear.org/File:Stage_2_in_sim.png Altitude Vs Time in Sim]] [[http://wiki.flightgear.org/File:Stage_2_scom.jpg Altitude vs Time in Real]] | |||
=== CSS DAP schemes for ascent === | === CSS DAP schemes for ascent === | ||