Project Apollo - NASSP (also known as NASSP or NCPP) is an add-on for the Orbiter space flight simulator. Project Apollo simulates the Apollo missions to Earth orbit and the Moon, and is slowly expanding to simulate planned post-Apollo missions that never flew. Project Apollo features a near-full implementation of the control panels in the Command Module and Lunar Module, and an increasingly accurate simulation of the internal systems (e.g. electrical distribution, fuel cells). Also the Virtual AGC software is supported, which allows you to run precisely the same on-board guidance software as used by the real Apollo Guidance Computer. This video demonstrates a lunar landing near the crater Tycho with Zerlina 56. Zerlina 56 was a development branch of the software for the Apollo Guidance Computer in the Lunar Module. Used to develop new features for Luminary, the main Lunar Guidance Computer branch, revision 56 of Zerlina contains several updates that were in the testing stage. Some of these updates were approved and later used for Apollo 15 to 17, but others were not included in Luminary and so were never used for a lunar landing mission. This video mainly demonstrates the experimental changes to Program 66, which is the final program the computer is running prior to the landing. Below follows a short description of the special features in Zerlina that were never included in the mission software. The Zerlina 56 source code was provided to the Virtual AGC project by Don Eyles, one of the original developers of the LGC software. Many thanks to him and the Virtual AGC team for providing, transcribing and assembling Zerlina and many Luminary versions so that they can be used in NASSP! Variable Servicer: The Variable Servicer was invented to prevent the Apollo 11 problems with 1201/1202 program alarms from happening again. Essentially the guidance cycle for the landing programs (nominal 2 seconds) becomes variable. So in the off-nominal case that the 2 seconds isn't long enough for all the necessary calculations to be done, the guidance cycle gets extended. The Servicer in Luminary drops less important tasks and causes the known program alarms instead. Because a nominal descent is shown in this video, the special abilities of the Variable Service don't have an effect. P66 velocity redesignations: In P66 while under automatic computer control the Attitude Control Assembly can be used to command horizontal velocities. This can be used to cancel out biases of the landing radar and/or to command small translations while hovering over the surface. P66 LPD: Based on an idea by John Young, P66 shows an angle for the Landing Point Designator. Based on the current forward velocity, the LPD angle is calculated under the assumption that the LM under automatic control by the LGC starts nulling the horizontal velocity at that instance. This can be used to land to land at a precise landing spot while in automatic control mode (Auto P66). Resources: Luminary memo by Don Eyles about the Variable Servicer: https://www.ibiblio.org/apollo/Documents/LUM139_text.pdf Luminary memo about the special P66 features in Zerlina: https://www.ibiblio.org/apollo/Documents/LUM171-DE_text.pdf Orbiter Downloads: Orbiter 2016: http://orbit.medphys.ucl.ac.uk/download.html Orbiter DX9 Graphics Upgrade: http://d3d9client.codeplex.com/ Orbiter Sound 4.0: http://orbiter.dansteph.com/forum/index.php?page=download Project Apollo - NASSP: http://nassp.sourceforge.net/wiki/Main_Page NASSP development snapshots: https://github.com/dseagrav/NASSP/releases

• published: 13 Sep 2017
• views: 7525