How the Lunar Module improved flight on Earth ✈️

7 responses to “How the Lunar Module improved flight on Earth ✈️”

1. 

   jurvetson

   Jul 25, 2021 at 2:44 am

   More details on my AGC here
   And a matching photo, before the interface modules and cable harnesses were added:My pallet is still in the F-8 flight configuration, with the AGC + IMU gyro ball + program memory + some interface modules for the DFBW application. I was wondering about the extensive cooling system routing through a tray below each Lunar Module computing subsystem and running to the coolant plumbing box in the back right corner. From p.59 of the NASA book:
   “Installing the Apollo Digital Computer System
   The main problem with using the Apollo guidance computer and its associated systems was that it needed active cooling while it was running. It was not designed to be air-cooled, so the computer and the cooling system had to share space.

   Throughout the conversion process, nothing caused a longer string of difficulties than the coolant system. The idea was to build a pallet plumbed for liquid cooling. The pallet would be shipped to Delco and the Apollo equipment installed. KECO, of Santa Ana, supplied a liquid nitrogen and ethylene glycol system that used a coolant loop to create cold sinks, which would absorb heat adjacent to the computer and inertial measurement unit.”

   The IMU ball is itself a work of art, an incredible electromechanical gyro inside a gyro. Here is a writeup I did on another one I have, to peer inside:
   And the programming interface, the Apollo DKSY
   From the Smithsonian:"In 1972, NASA research pilot Gary Krier became the first to fly a digital fly-by-wire aircraft":

   Reply
2. 

   jurvetson

   Jul 25, 2021 at 4:20 pm

   Cool details on the SOFTWARE in the core ropes, from the same NASA book:

   “There were two copies of DIGFLY in the core rope. It was the lone program assembly, in contrast to Apollo software with separate programs for different flight phases. DIGFLY was divided into system and application components. The system software consisted of an executive that provided task management, a restart segment that could re-initialize hardware and software in flight, and service routines to monitor the inertial measurement unit, provide self-tests, control the interface, and handle interrupts. The application software had flight control and some miscellaneous components. The flight-control portion did the mainline processing of the control laws, handled the mode and gain changes made by the pilot, and processed input from the sensors. Among the miscellaneous components were ground-test software and special-purpose applications.

   Since parts of the software were similar to the Apollo code, some of it could be reused like the hardware. The display code, executive, and inertial-measurement unit alignment were taken from the Apollo 14 lunar module flight software load. The self-tests came from the Apollo pre-flight erasable memory load. Sixty percent of the eventual F-8 software was taken from Apollo.

   Each flight, the ground crew would prepare [802 before the pilot got in the cockpit. The airplane would be connected to a power cart and a ribbon cable to a tape reader. The main software was in the core rope, but all the data needed could not be stored in the permanent memory. A flight-test program needs flexibility, therefore, before every flight, the KSTART software load would be put in the erasable memory.

   The Apollo computer had only 2,000 words of erasable memory. These could be used by the software developers at the Flight Research Center to specify data constants, indicate the storage location of data to be telemetered to the ground, and even store short programs. Up to 105 variables could be adjusted for each flight.”

   

   and some detail on the hand-weaving of the rope memories from the Smithsonian book Milestones of Space

   Reply
3. 

   jurvetson

   Jul 25, 2021 at 4:35 pm

   ON NEIL ARMSTRONG’S SPONSORSHIP ROLE

   From discussion with Albion Bowers who was working on this first hand: “We fried an Apollo flight computer. So, we had to get a replacement. Neil Armstrong was the Associate Administrator of Aeronautics at the time and procured a replacement from Apollo 15. The control sticks came as well. One of these sat on my desk for a decade.

   We had planned to use the FBW to fly the F8 Oblique Wing Research Aircraft. The FBW can “straighten out” the asymmetry of the aircraft to make it feel “normal” to the pilot. We used the FBW tech for the FSW X29, thrust vectoring control on the F18 HARV, and x31, and it was expanded on the F15 ACTIV (formerly the STOL MTD) to research adaptive controls in failure modes. It was also extended to automatic ground collision avoidance.”

   From the same NASA book:

   "At NASA Headquarters, Burke and Jarvis had an advantage when they gave their sales pitch. They had to start at the Office of Advanced Research and Technology, and at that time Neil Armstrong was a Deputy Associate Administrator for Aeronautics. Burke knew Armstrong from the X-15 project. They also had to deal with Peter R. Kurzhals and Frank J. Sullivan, the successive directors of electronic guidance and control research, but Armstrong had an immediate interest that made him their key ally. He wanted to see more technology transfer from the Apollo program. When told of the analog versus digital debate and the difficulty of finding a reliable airborne computer, he said to Burke and Jarvis, “I just went to the moon with one.” In fact, the Apollo computer was one of the most reliable ever built. With the Apollo program shortened, there were plenty of machines available. Armstrong suggested contacting the Draper Laboratory to explore the feasibility of using modified Apollo hardware and software on the F-8."

   Reply
4. 

   jurvetson

   Jul 25, 2021 at 4:36 pm

   ON NASA CULTURE AND ENTREPRENEURSHIP

   From the closing paragraph of the NASA book:

   "The most obvious common characteristic among almost all of these men while they worked on the F-8 is youth. They were mostly in their 20s and 30s, and, with a few exceptions, were playing a major role in a program for the first or second time. In many ways they resembled the teams that made up the Apollo Project: young engineers, often right out of school, with seemingly limitless confidence and energy."

   And from the opening: "NASA’s digital fly-by-wire project is remarkable for its impact on the evolution of flight control systems but is also a case study in how engineers sold ideas and conducted research at the NASA Flight Research Center during the late 1960s and throughout the 1970s. Arguably, the fly-by-wire project could not be done as easily today since the channels for selling project ideas and obtaining funding are more complex now. This is due to formality and layers of bureaucracy that did not exist in the 1960s. Even in the personnel-bloated Apollo era, NASA engineers knew their headquarters counterparts informally. If a proposed project could get past the Center director and find a champion at headquarters, the engineers and their advocate could usually work out a proposal that would sell, even if the resulting funding was little more than a start. Projects that capitalized on the seed money would, if not prosper, at least survive. As Krier climbed out to the northeast, there was no doubt that the fly- by-wire project had spent its startup money well."

   Reply
5. 

   jurvetson

   Jul 25, 2021 at 6:34 pm

   AIRBUS AND BOEING — From the NASA book:

   "Successful tests with this conventional F-8 airframe would pave the way for the unconventional: the Space Shuttle Orbiter, the B-2 flying wing, and commercial airliners like the Airbus A-320 or Boeing B-777 with smaller, lighter control surfaces and almost unimaginable reliability.

   It was left to the relatively young Airbus to make the leap into the future and challenge Boeing’s domination of the narrow-body airliner market with an advanced airplane using a flight-control architecture different from the American prototypes. The Airbus A- 320 has a high level of success with its control system, which features a unique architecture to enhance reliability. The Airbus flight control system has migrated to all new models of that firm’s aircraft.

   Even the conservative industry dominator, Boeing, has launched the B-777 with a digital control system of more conventional design.

   There are two separate control systems in Airbus fly-by-wire aircraft. If one or the other system fails completely, the remaining one becomes the backup. It is quite possible to fly an Airbus using spoilers for ailerons, and also without the spoilers, but the elevator control is built into both systems because that is still the primary control surface for pitch, and any other arrangement would not do. This rather Byzantine system is claimed to have a reliability of about one failure in 10 trillion operations, the highest ever achieved.

   Boeing finally built an airliner with fly-by-wire controls, the 777. The control system is more straightforward than that used by Airbus. It contains three “lanes” of three different computers each: an AMD 29050, a Motorola 68043, and an Intel 80486. Boeing is reportedly discovering one little- anticipated problem with choosing fly-by-wire: all the computer manufacturers supplying the processors are trying to stop new fabrication of these older machines."

   Reply
6. 

   Dave Huntsman

   Jul 26, 2021 at 3:23 am

   Outstanding history!!

   Reply
7. 

   magnus_jo

   Sep 29, 2021 at 1:57 pm

   Thanks for sharing this great info with us. 🌟

   Reply