Did Apollo do a burn prior to re-entry?

On Mar 6, 1:36 am, (Henry Spencer) wrote:
Apollo dropped the skip partly because it also
dropped its original requirement for a landing in the continental US.

The CSM software still had 'skip' capability if it was required
though... obviously no Apollo mission ever did, but presumably if
they'd had to return in an emergency at a time when they couldn't
target the correct landing site it might have been used.

Mark

In article .com,
wrote:
Apollo dropped the skip partly because it also
dropped its original requirement for a landing in the continental US.

The CSM software still had 'skip' capability if it was required
though... obviously no Apollo mission ever did, but presumably if
they'd had to return in an emergency at a time when they couldn't
target the correct landing site it might have been used.

Yes, I believe the option did still exist, in the primary guidance system.
(The other part of why the skip was dropped was that neither of the backup
reentry-guidance systems could do it.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Charles Buckley wrote:

I've never seen a drawing of it, but I once ran into a mention of a
Rogallo wing equipped Apollo.


Would not be surprised as Rogallo wings were the original idea
for Gemini. My guess is that you are talking about a later
block of Apollo capsule. Maybe a design concept from about 1967-69
for Apollo upgrades?

http://www.astronautix.com/craft/apollox.htm
There's more on it he
http://www.hq.nasa.gov/office/pao/Hi...205/ch4-2.html
I can see two problems with this right off the bat:
1.) Unlike Gemini, Apollo has the docking tunnel at the front; so where
do you put the nose gear?
2.) If it doesn't work, you are going to want to eject. That means an
extra pair of either hatches or blow off panels, and everyone sitting in
ejection seats.
Complex and heavy.

Pat

On Mar 6, 2:48 am, Pat Flannery wrote:
I've never seen a drawing of it, but I once ran into a mention of a
Rogallo wing equipped Apollo.

My favorite was the plan to return the entire Saturn I first stage
that way:

http://history.nasa.gov/MHR-5/Images/fig032.jpg

Mark

Henry Spencer wrote:
There were a number of ideas for just how to bring an Apollo down on land,
and if you read early Apollo papers, you can find details and even some
test results -- for example, there was substantial testing done on braking
rockets for touchdown.


One clever idea that Soyuz had was to jettison the heatshield prior to
landing, getting rid of a lot of weight.
If that had been done on Apollo with its huge heatshield, then you could
easily see the parachutes bringing it down on land safely, maybe without
even needing braking rockets.
I imagine Glenn's flight might have argued against this concept.

Pat

wrote:


The CSM software still had 'skip' capability if it was required
though... obviously no Apollo mission ever did, but presumably if
they'd had to return in an emergency at a time when they couldn't
target the correct landing site it might have been used.



There's and endoatmospheric skip shown he
http://www.nasm.si.edu/collections/i...RES/Fig22d.jpg
Apollo 10 apparently used this, based on the G levels during descent:
http://history.nasa.gov/SP-368/p135b.htm

Pat

wrote:
My favorite was the plan to return the entire Saturn I first stage
that way:

http://history.nasa.gov/MHR-5/Images/fig032.jpg


That thing would be a flying battering ram. :-)
From the tailfin size on that particular one, it looks Dyna-Soar related.
I still like Winged Titan: http://www.astronautix.com/lvs/wintitan.htm
http://www.friends-partners.org/part...t/titnwing.gif

Pat

"Pat Flannery" wrote in message
...

wrote:

The CSM software still had 'skip' capability if it was required
though... obviously no Apollo mission ever did, but presumably if
they'd had to return in an emergency at a time when they couldn't
target the correct landing site it might have been used.

There's and endoatmospheric skip shown he
http://www.nasm.si.edu/collections/i...RES/Fig22d.jpg
Apollo 10 apparently used this, based on the G levels during descent:
http://history.nasa.gov/SP-368/p135b.htm

Both pictures depict a lifting re-entry, *not* a skip re-entry. A skip
re-entry would have the CM dip into, then out of, the atmosphere before
entering again. When out of the atmosphere, the CM would have no control of
its trajectory because there would be no atmospheric lift.

If Apollo 10 had performed a skip re-entry, the plot of the g-loading during
reentry would have dipped to zero after the first dip into the atmosphere.
But we clearly don't see this in Apollo 10's graph.

The amazing thing is that the CM's shape could have generated more lift, but
it was crammed so tighly with equipment that they couldn't position the CG
to take advantage of this potential lift. If NASA is smart, when they
design the CEV, they'll make sure they can take advantage of this extra lift
by doing a better job of positioning the CG.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

On Mar 6, 9:54 am, (Henry Spencer) wrote:
The CSM software still had 'skip' capability if it was required
though... obviously no Apollo mission ever did, but presumably if
they'd had to return in an emergency at a time when they couldn't
target the correct landing site it might have been used.

Yes, I believe the option did still exist, in the primary guidance system.
(The other part of why the skip was dropped was that neither of the backup
reentry-guidance systems could do it.)

Using P65:
http://www.ibiblio.org/apollo/NARA-S...v6-P40-P69.pdf

--
Mariano Chouza

Jeff Findley wrote:
"Pat Flannery" wrote in message
...

wrote:

The CSM software still had 'skip' capability if it was required
though... obviously no Apollo mission ever did, but presumably if
they'd had to return in an emergency at a time when they couldn't
target the correct landing site it might have been used.

There's and endoatmospheric skip shown he
http://www.nasm.si.edu/collections/i...RES/Fig22d.jpg
Apollo 10 apparently used this, based on the G levels during descent:
http://history.nasa.gov/SP-368/p135b.htm


Both pictures depict a lifting re-entry, *not* a skip re-entry. A skip
re-entry would have the CM dip into, then out of, the atmosphere before
entering again. When out of the atmosphere, the CM would have no control of
its trajectory because there would be no atmospheric lift.

If Apollo 10 had performed a skip re-entry, the plot of the g-loading during
reentry would have dipped to zero after the first dip into the atmosphere.
But we clearly don't see this in Apollo 10's graph.


I should have used another term for the maneuver.
Note I said "endoatmospheric" not "exoatmospheric", indicating that it
stayed in the outer atmosphere during the maneuver.

Pat