Question NASA's MEDS compared with our MFDs?

MikeB

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I've read a little about the Space Shuttle's Multi-functional Electronic Display System (MEDS), which seems to be the real-world equivalent of our MFDs. They appear to provide very different functions than our standard and add-on MFDs, largely derived from the original electro-mechanical gauges and CRT displays. I have three related questions:

1. Can the experts in our community provide a comparison of the functions that NASA provides to Shuttle crew with the functions that our developers provide to us orbinauts?

2. Where functions are similar, can they comment on the differences in inputs and displays?

3. Are there publicly-available documents that describe the operation of NASA's MEDS-based functions?
 

Urwumpe

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3. Are there publicly-available documents that describe the operation of NASA's MEDS-based functions?

First of all: Yes.

http://www.nasa.gov/centers/johnson/pdf/359895main_DPS_G_K_7.pdf

1. Can the experts in our community provide a comparison of the functions that NASA provides to Shuttle crew with the functions that our developers provide to us orbinauts?

2. Where functions are similar, can they comment on the differences in inputs and displays?


The MEDS is closer to the EFIS displays of a modern jetliner, to the Orbiter MFDs - it is actually derived from commercial EFIS parts.

You have only a coarse similarity, like the three main MEDS display modes being similar to the combination of Surface MFD and MSI MFD and just Surface MFD. also you have special displays:

* Control Surface Deflection (SPI DISPLAY)
* OMS/MPS parameters (OMS/MPS)
* APU/hydraulic system parameters (APU/HYD)

The AE Primary Flight Display shows (PFD) all the data you have in Surface MFD and HSI MFD, but also contains special indications for the Space Shuttle. For example, the arrow labeled "E" in the HSI portion displays the direction of the Earth relative velocity (VRel, relative to surface of Earth). The arrow "I" displays inertial velocity vector (relative to the center of Earth). "R" shows direction to runway during powered flight. "H" shows heading to HAC intercept point in gliding flight. "C" shows heading to the HAC center. Like always in real space shuttle displays, many quantities and vectors are only displayed when the software is calculating them, this depends on flight phase and software load.

Additionally, you have a special DPS mode, which emulates the old Display Electronics Unit and CRT combination of the old shuttle flight deck. Practically, the subsystems DEU/CRT/keyboard or the IDP/DPS mode MFD/keyboard are nothing else but a terminal for a single GPC. The old DEU took complete display data from a GPC and rendered it as vector display (no pixels, just a electron beam that paints the image, just like you would use a single laser pointer on a wall), and took the keypresses from the keyboard, validated the input and sent the keyboard inputs to the GPC, once a complete and valid line was entered. In the modern MEDS, the IDP replaced the role of the DEU, converting the display data from DEU format to the MFD format.
 
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