aborting a lunar lander

Henry Spencer wrote:

There was probably a spec somewhere for how big a fall the LM was expected
to survive with the ascent stage still intact... but I don't know what it
was, offhand. Given the rather lightweight construction, I'm sure it was
meters, not tens of meters.


According to this, 3.05 MPS vertical velocity and 1.22 MPS horizontal
velocity; but what Grolsch beer glass design has to do with this all is
a bit beyond me:
http://dutlsisa.lr.tudelft.nl/Vehicl...ng/Landing.pdf
.....although I applaud the concept of using beer as a teaching aid, and
I assume the guy driving the car into the tree has had one too many
Grolschs. :-D

Pat

In article ,
Pat Flannery wrote:
There was probably a spec somewhere for how big a fall the LM was expected
to survive with the ascent stage still intact... but I don't know what it
was, offhand. Given the rather lightweight construction, I'm sure it was
meters, not tens of meters.

According to this, 3.05 MPS vertical velocity and 1.22 MPS horizontal
velocity...

Hmm, at a surface gravity of 1.62m/s^2, assuming engine failure at zero
vertical velocity, that's a 2.9m drop. Of course, that's probably the
maximum for an undamaged landing on a worst-case surface (solid rock),
after safety margins. The normal surface isn't *quite* that hard, and if
you're going to leave immediately, you don't care how much of the descent
stage gets crushed so long as the ascent stage is intact. If it's a clean
vertical drop onto a reasonably flat surface, 5-10m might well be okay.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

Henry Spencer wrote:

Hmm, at a surface gravity of 1.62m/s^2, assuming engine failure at zero
vertical velocity, that's a 2.9m drop.


They also might have figured that it could come down at an angle so that
one leg took the brunt of the initial impact.

Of course, that's probably the
maximum for an undamaged landing on a worst-case surface (solid rock),
after safety margins. The normal surface isn't *quite* that hard, and if
you're going to leave immediately, you don't care how much of the descent
stage gets crushed so long as the ascent stage is intact.


If it's due to motor failure rather than propellant depletion, there are
those crushed fuel and oxidizer tanks to contend with- you might lift
off again immediatly....via a big explosion in the descent stage.

If it's a clean
vertical drop onto a reasonably flat surface, 5-10m might well be okay.


Where is that legendarily tough Grumman landing gear? ;-)

Pat

In article ,
Pat Flannery wrote:
...The normal surface isn't *quite* that hard, and if
you're going to leave immediately, you don't care how much of the descent
stage gets crushed so long as the ascent stage is intact.

If it's due to motor failure rather than propellant depletion, there are
those crushed fuel and oxidizer tanks to contend with- you might lift
off again immediatly....via a big explosion in the descent stage.

You don't normally get a major explosion out of hypergolics. Although, of
course, it wouldn't take that much to damage something as fragile as the
ascent stage.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

You don't normally get a major explosion out of hypergolics. Although, of
course, it wouldn't take that much to damage something as fragile as the
ascent stage.
--

Ahh the big problem would be coming down out of level by say partially hitting
a boulder ior one leg in a crater. too far off level and you cant take off but
I forget the angle...
HAVE A GREAT DAY!

You are absolutely correct. I just wish folks would do their homework by
reading reputable history books. Both Stafford and Cernan have witten
about the incident on Apollo 10.

Matthew Ota

Jay Windley wrote:

"Jonathan Silverlight" wrote
in message ...
|
| They got into a spin and nearly crashed.

But that was because a guidance system switch had been set improperly, not
because the separation induced the spin.

There is always a danger aborting at low altitudes, and I'm sure the
astronauts, as seasoned test pilots, were well aware of what their options
were.

"Matthew Ota" wrote in message
...
|
| You are absolutely correct. I just wish folks would do their homework by
| reading reputable history books. Both Stafford and Cernan have witten
| about the incident on Apollo 10.

It's a great story, not just because of the inherent drama but because of
some of the things that arose in its aftermath.

Cernan yelled, "Sonuvabitch!" over the A/G loop when it happened.
Understandable, given the circumstance. Most pilots get a little put out
when their craft tries to align itself to an imaginary (and wrong) notion of
"up". Of course the blue-crested religious types descended on NASA and
demanded St. Eugene be reprimanded. According to Cernan that incident
actually softened NASA's stance on vulgarity over the airwaves. You can
only expect pilots not to be pilots to some extent.

When you go back and talk to Cernan and Stafford and try to understand what
happened, they tell you that each man flipped the switch to select the
guidance mode. Neither pilot *looked* at the switch; the checklist said to
select a certain mode, and because of how the mission went, each pilot knew
that in order to obey the checklist he would have to reverse the position of
the switch to select that mode. So Stafford did it. And then Cernan did it
too. Being able to operate a craft's controls without looking at them is a
skill pilots have to develop.

Anyway, when it came time for Cernan to be in the pilot's "seat" for Apollo
17, he tells of drawing a chalk line down the LM instrument panel. Every
switch left of the line belonged to Cernan and everything to the right of it
belonged to Schmitt. Woe betide the astronaut whose hand strayed across
that line. Funny, and yet sensible.

--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org

In message , Jay Windley
writes

"Matthew Ota" wrote in message
...
|
| You are absolutely correct. I just wish folks would do their homework by
| reading reputable history books. Both Stafford and Cernan have witten
| about the incident on Apollo 10.

It's a great story, not just because of the inherent drama but because of
some of the things that arose in its aftermath.

Cernan yelled, "Sonuvabitch!" over the A/G loop when it happened.
Understandable, given the circumstance. Most pilots get a little put out
when their craft tries to align itself to an imaginary (and wrong) notion of
"up". Of course the blue-crested religious types descended on NASA and
demanded St. Eugene be reprimanded. According to Cernan that incident
actually softened NASA's stance on vulgarity over the airwaves. You can
only expect pilots not to be pilots to some extent.

According to the transcript at
http://www.jsc.nasa.gov/history/mission_trans/apollo10.htm there are 21
instances of "son of a bitch" in the LM transmissions. Makes sense when
you're flying with Snoopy :-)

On 2004-08-26, Jonathan Silverlight
wrote:

According to the transcript at
http://www.jsc.nasa.gov/history/mission_trans/apollo10.htm there are 21
instances of "son of a bitch" in the LM transmissions. Makes sense when
you're flying with Snoopy :-)

And they have the temerity to say the Internet isn't educational...

--
-Andrew Gray