posted 08-03-2021 04:24 AM
Didn't know this until today — the landing skirt on the Apollo 15 lunar module Falcon buckled on landing?
From Andy Sanders ("Apollo Remastered") on Twitter:
Here I've produced for you, from 16mm film frames (HD source Stephen Slater), an enhanced view from Jim Irwin's window as they approach the landing spot (red dot). The landing buckled the engine skirt.
David C Member
Posts: 1284 From: Lausanne Registered: Apr 2012
posted 08-03-2021 08:00 AM
Very old news, it’s in the Mission Report.
Robert Pearlman Editor
Posts: 46760 From: Houston, TX Registered: Nov 1999
posted 08-03-2021 02:51 PM
Very interesting reading the older thread.
Blackarrow Member
Posts: 3351 From: Belfast, United Kingdom Registered: Feb 2002
posted 08-03-2021 06:24 PM
The issue was also addressed in some technical detail in the thread Apollo lunar module touchdown dynamics and I recommend the book "Digital Apollo" by David A. Mindell.
AlanLawrie Member
Posts: 97 From: hitchin, herts, UK Registered: Oct 2003
posted 08-04-2021 10:54 AM
The possibility of the nozzle extension impacting the lunar surface was specifically designed for and tested by the engine supplier TRW. They built a "crushing test fixture" and subjected a columbium (niobium) nozzle extension to a simulated 10 ft/sec landing impact by compressing the nozzle extension 28 inches in less than half a second.
oly Member
Posts: 1244 From: Perth, Western Australia Registered: Apr 2015
posted 08-04-2021 06:46 PM
The lunar module descent engine nozzle contacting the lunar surface was a design factor of both the spacecraft and the flight plan.
A reason that the landing probes and the contact light were incorporated into the spacecraft design was to provide a proximity alert for when the vehicle was considered close enough to the lunar surface that the descent engine could be shut down, and the vehicle could settle to the surface as a safe velocity.
The reason that the flight plan was designed, and practiced in simulation, for the engine to be shut down before surface contact was to avoid a situation whereby a rock or lunar soil could potentially plug the descent engine nozzle and cause a catastrophic failure.
This scenario is also why astronauts inspected and photographed the gear, nozzle, and underlying lunar surface, and gave feedback during the EVA.
The realigned landing footage of Apollo 14 details the surface rocks, craters, and surface undulations that were potential hazards, and also shows that the vehicle could withstand a gentle landing with the engine still running.
From what I understand, one of the biggest lunar module engineering surprises was how little amount the landing gear was compressing during the landing, as engineers had expected and designed for a greater gear compression.
With the gear legs not compressing as far as was anticipated, the distance from the lower ladder rung to the gear footpad was greater than expected, one of the reasons Armstrong made sure that he could get back up the ladder (however, I suspect that in a pinch, a lunar surface experiment package or rock box could be used as a step).
posted 08-03-2021 04:24 AM
advertisement