Luna 9, soft or hard lander?

Are probes like the soviet Luna 9 & 13 considered soft landers or hard
landers? Years ago, all the sources that I came across insisted that
soft landers had to use braking rockets to cut velocity, and that the
Lunas (and, by extention, probes that use airbags, like MER) were
survivable hard landers, ejected by a bus which then crashed onto the
surface. Is this distinction still used?

I have not heard the distinction used, but I still cling to it. A hard
lander is one that has significant vertical rate that is dissipated in a
mechanical crush (or bounce) system, in my book. But it's an old fashioned
book.



wrote in message
oups.com...
Are probes like the soviet Luna 9 & 13 considered soft landers or hard
landers? Years ago, all the sources that I came across insisted that
soft landers had to use braking rockets to cut velocity, and that the
Lunas (and, by extention, probes that use airbags, like MER) were
survivable hard landers, ejected by a bus which then crashed onto the
surface. Is this distinction still used?

Jim Oberg wrote:

I have not heard the distinction used, but I still cling to it. A hard
lander is one that has significant vertical rate that is dissipated in a
mechanical crush (or bounce) system, in my book. But it's an old fashioned
book.




Better be careful on that one; the LM used the crushable honeycomb in
its landing legs to take up the impact.
http://www.hq.nasa.gov/alsj/a11/a11lm5strut.jpg
The Soviets stuck pads of crushable honeycomb on the bottom of the LK's
landing pads.
(can you imagine a pneumatic system? It lands, compresses, and lifts
right off again...this is the one Wile E. Coyote would use.)

Pat

Pat Flannery wrote:

snip

The Soviets stuck pads of crushable honeycomb on the bottom of the LK's
landing pads.
(can you imagine a pneumatic system? It lands, compresses, and lifts
right off again...this is the one Wile E. Coyote would use.)

Okay, my interest is piqued.

Among the 60+ images I have of the LK mock-ups and engineering
boiler-plates, about 20 show legs with plain ol' dished feet on the
end. The legs, as expected, are awfully Luna 16/17/20/24 esque and the
main (presumably compressive) member that runs to the leg appears to be
fashioned from two sections with different diameters - strongly
suggesting a stroking action of some sort that compresses an inner
friable material.

My copies of Planetokhodii, and Moving on the Soils of the Moon and
Planets, are frustratingly mute about the landing gears. Just lots of
multi-line graphs, and faded images of half-tank half-VW machines with
improbable articulation climbing the barren wastes of Kazakhstan.

If you've concrete info about the LK gear, I'm all ears. I agree that
it cannot be Comrade Coyote's system (best example ever of a
Running-Dog of the Western Imperialists) - but the LK was no mere
Surveyor.

-James Garry

wrote:


If you've concrete info about the LK gear, I'm all ears.




I saw a photo of one of the prototypes stored away that had a
disc-shaped piece of honeycomb attached to the base of each of the
landing pads. This was pretty chewed up, and I think they removed it
from the ones they put on display as it would just crush under the
weight of the LK anyway when you put it on the ground (the stored one
was being held clear of the ground by a support structure under it). You
can see it on these drawings of the LK:
http://www.astronautix.com/graphics/l/lkkaluga.jpg
http://www.astronautix.com/graphics/l/lkkaluga.jpg
I assume that the landing gear's shock absorption system worked in a
manner very similar to that of the LM, and that the crushable honeycomb
pads were just to give some extra shock absorption on landing.

Pat

Pat

Pat Flannery wrote:

You can see it on these drawings of the LK:
http://www.astronautix.com/graphics/l/lkkaluga.jpg
http://www.astronautix.com/graphics/l/lkkaluga.jpg

Whoops, wrong graphic: http://www.myspacemuseum.com/lkscan.jpg

Pat

On Sun, 17 Sep 2006 00:31:16 -0500, Pat Flannery
wrote:

You
can see it on these drawings of the LK:
http://www.astronautix.com/graphics/l/lkkaluga.jpg
http://www.astronautix.com/graphics/l/lkkaluga.jpg

....Speaking of Mark Wade:

http://www.astronautix.com/data/index.htm

....Ok, Evolvo Lad, confess: how many of these were supplied by Rusty
:-)


OM
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In article .com,
wrote:
Are probes like the soviet Luna 9 & 13 considered soft landers or hard
landers? Years ago, all the sources that I came across insisted that
soft landers had to use braking rockets to cut velocity, and that the
Lunas (and, by extention, probes that use airbags, like MER) were
survivable hard landers, ejected by a bus which then crashed onto the
surface. Is this distinction still used?

That terminology isn't much heard now, perhaps because we now also have
*really* hard landers: penetrators, which come in at 200-300m/s (vs. the
10-20m/s acceptable for airbag or crushable-padding systems, and the
0-5m/s typical of rocket landing). It was played up in the 60s to
emphasize the technical superiority of Surveyor 1 over Luna 9.

Note that *all* these systems need braking rockets for a lunar landing,
because an undecelerated lunar impact is 2000-3000m/s (even from lunar
orbit, it's 1700m/s or so). In fact, MP and the MERs needed braking
rockets, fired by a radar altimeter, on Mars -- the atmosphere is too thin
for a reasonable parachute to bring descent velocity down to what the
airbags could take. The only big difference is how precise the control of
the rockets has to be: penetrators can probably get by with preprogrammed
timing, airbag systems need an altimeter to fire the rockets just before
impact, and rocket landers need throttling capability as well.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

In article ,
Pat Flannery wrote:
I have not heard the distinction used, but I still cling to it. A hard
lander is one that has significant vertical rate that is dissipated in a
mechanical crush (or bounce) system, in my book...

Better be careful on that one; the LM used the crushable honeycomb in
its landing legs to take up the impact...
The Soviets stuck pads of crushable honeycomb on the bottom of the LK's
landing pads.

The key really has to be "significant vertical rate", not "crush", since
honeycomb and similar materials are widely used for one-shot shock
absorbers even in rocket-landing systems. There was crushable honeycomb
in the Surveyor footpads (rather conspicuous in the footpad photos from
the lunar surface), and more in blocks under the spacecraft body (which
would touch down if the leg shock absorbers stroked fully).

(can you imagine a pneumatic system? It lands, compresses, and lifts
right off again...this is the one Wile E. Coyote would use.)

The Surveyor leg shock absorbers *were* at least partly pneumatic, I
believe, and the Surveyors did bounce a bit.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Henry Spencer wrote:

The Surveyor leg shock absorbers *were* at least partly pneumatic, I
believe, and the Surveyors did bounce a bit.



I wonder if the LK used a partially pneumatic system also- that would
explain the four "nesting" rockets that fired on touchdown:
http://www.astronautix.com/graphics/q/qlklndts.jpg
(what's interesting about that picture is the conical top on the thing-
it looks more sophisticated than a simple support structure, and one
wonders what it is).

Pat