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  Mercury - Gemini - Apollo
  Apollo lunar module engine shock wave testing

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Author Topic:   Apollo lunar module engine shock wave testing
GACspaceguy
Member

Posts: 1789
From: Guyton, GA
Registered: Jan 2006

posted 04-20-2015 09:50 AM     Click Here to See the Profile for GACspaceguy   Click Here to Email GACspaceguy     Edit/Delete Message   Reply w/Quote
Last week, I found another Grumman engineer here at Gulfstream (which was a Grumman GII assembly facility when it first came to the Savannah area in 1968). Turns out, he did work on shock waves on the lunar surface, which to me is amazing in that I would have never thought about a shock wave in a place that had no atmosphere. I introduced myself as a collector via e-mail and here is his response (posted by permission):
Actually, the only stuff I collected were photos of some of the results of my Shock Tunnel testing (almost five years of it) of the landing of the descent stage of the LM (20th scale) and the lunar take-off of the ascent stage (10th scale). The entire external passive cooling system for the LM was based on that data and my analyses of it. The other thermo guys used my data and analysis of it to design the details of the protection system. I've enclosed some of the photos taken for your collection. (Test duration was on the order of 6 milliseconds before the vacuum chamber would increase in pressure and destroy the vacuum causing the exhaust plume to collapse.)

The probes on Figure 1 are significantly oversized models of the automatic engine shutoff sensors/switches that were installed in case the astronauts flubbed it. Three of the four landing pads had them. Only the pad that held the access ladder did not. NASA was concerned it would get bent somehow on landing and trip up the Astronauts during egress.

You can see the dish shaped shock wave being swallowed by the engine as LM approaches the surface of the "Moon." The reverse happens during ascent.

The 1/4" circular dots were Grumman designed and built thin film Quartz/Platinum calorimeters which measured the heat transfer coefficients, that allowed for the material design of the thermal protection system.

Just prior to the first lunar landing, NASA got wind of our test facility and made up run a full scale test in Vacuum "B" down at NASA Houston. The results were identical to our subscale testing of the same geometries. (They were quite impressed.)

(All of this occurred between 1965 and 1969. That was the end of the "Good Old Days". Almost everything was done with slide rules.

David C
Member

Posts: 321
From: Pasadena
Registered: Apr 2012

posted 04-20-2015 10:03 AM     Click Here to See the Profile for David C     Edit/Delete Message   Reply w/Quote
Great stuff thanks. Do you have anymore of these?

GACspaceguy
Member

Posts: 1789
From: Guyton, GA
Registered: Jan 2006

posted 04-20-2015 12:16 PM     Click Here to See the Profile for GACspaceguy   Click Here to Email GACspaceguy     Edit/Delete Message   Reply w/Quote
That is all he sent me.

One Big Monkey
Member

Posts: 85
From: West Yorkshire, UK
Registered: Jul 2012

posted 04-20-2015 01:25 PM     Click Here to See the Profile for One Big Monkey     Edit/Delete Message   Reply w/Quote
Fascinating photos! Thanks for sharing them.

Joel Katzowitz
Member

Posts: 526
From: Marietta GA USA
Registered: Dec 1999

posted 04-20-2015 04:39 PM     Click Here to See the Profile for Joel Katzowitz   Click Here to Email Joel Katzowitz     Edit/Delete Message   Reply w/Quote
That's so cool Fred.

Space Cadet Carl
Member

Posts: 92
From: Lake Orion, Michigan
Registered: Feb 2006

posted 04-27-2015 11:01 AM     Click Here to See the Profile for Space Cadet Carl   Click Here to Email Space Cadet Carl     Edit/Delete Message   Reply w/Quote
The lunar rover video of the Apollo 17 lunar liftoff shows an exhaust pattern very similar what's shown in those photos... for less than a second right at liftoff.

All times are CT (US)

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