Space first stage recovery.

Side question: after spending 6 months in space, could the crew
realistically eject from capsule and parachute down or would their bones
be crushed as the hit the ground ?

the capsule is their lifeboat, i doubt they will add a escape system. although i am not following this closely

In article om,
says...

On 2016-01-06 05:42, Fred J. McCall wrote:

Wrong. They'll do water landings.

Is this for the first x landings after which, NASA will allow
legged/powered landings ?

Considering that NASA allows its crews to land on Soyuz, you'd think
they would at the best least allow a similar landing.

I assume that SpaceX's test unmanned flights will land powered, on legs ?

They have not yet, but will, similar to Grasshopper tests.

Should NASA allow powered/legged landings, where would the capsule land ?

Once proven, they should, but politics and the "safety mafia" may
prevent it.

Ideally, it would land in the very same place as the Falcon 9 first
stages. For "safety" Edwards Air Force Base until they can prove they
can land with precision.

California ? KSC/Cape Canaveral ? Is there post Columbia concern about
re-entry over USA ?

Far less chance of a capsule breaking up like Columbia, and a capsule is
far smaller than a shuttle, so I doubt it.

If you do a powered landing to an "X" on the ground, how difficult is it
without wings ?

If you can land a Falcon 9 first stage right on the "X" with a single
engine that can't deep throttle, you can do the same with a bi-conic
capsule with 8 engines that can deep throttle. In some ways, landing a
Dragon via Super Dracos will be easier.

Will the powered phase have much cross range capability
to still land on the X on the designated parking lot or will be be more
akin to the Soyuz where landing varies depending on (predicatble)
parameters such as phase of orbit, winds at different altitudes etc ?

Cross range is mostly a function of hypersonic lift. There is some lift
with a bi-conic capsule, so I'd expect landing on the "X" won't be all
that difficult. We've been doing this sort of thing since the 1960's
(steering during the hypersonic phase). It's textbook by now.

In the later case, how big an area do they need to handle all types of
parameters involved in de-orbiting from 51° orbit ?

The devil is in the details, but in a pinch, you use your parachutes and
land wherever you can. The Super Dracos can likely still be used to
cushion a land landing on uncertain terrain. Best case in a
contingency, you land in the ocean under the chutes. In a contingency,
you sacrifice the capsule for crew safety.

Side question: after spending 6 months in space, could the crew
realistically eject from capsule and parachute down or would their bones
be crushed as the hit the ground ?

Not an option with the current capsule designs, but would have been with
the shuttle. You'd have to ask someone who knows (former shuttle
program).

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In article m,
says...

On 2016-01-07 02:20, Fred J. McCall wrote:

There is no similarity between the two landings.

Soyuz lands on land with powered "brakes" just before landing. Seems
quite similar to what Dragon would be capable of, with expection of
landing on legs instead of belly on grass for Soyuz.

We've already told you they are different. You need to read up on the
details of both systems. They are *quite* different both in design and
in how they operate. Apples and oranges.

You might want to look at the accuracies for previous capsule
programs
(Mercury/Gemini/Apollo).

My concern isn't about the accuracy and predictability of a single
landing, it is with regards to how much landing spot varies every time a
Dragon falls out of the sky.

So look at the data from *all* the previous capsule landings and do the
math. It's not that hard.

In other words, if you have 20 landings from ISS and mark a spot for
each, how much of an area will that represent ? the size of DC or the
size of Texas ?

My guess is that it would be smaller than either of those, and that was
with unguided parachutes for the terminal phase. Using the variable
thrust Super Dracos will give positive control over the terminal phase.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In article om,
says...

On 2016-01-06 18:56, bob haller wrote:

the capsule is their lifeboat, i doubt they will add a escape system. although i am not following this closely


Escape system is for when at the launch pad or early in launch to allow
the capsule to get away from the stack in case of explosion and land safely.

Since Dragon V2 carries its "escape engines and fuel" to orbit and back,
it's arguably got more options during reentry. After a nominal launch,
those engines are intended to be the primary way to land with parachutes
as a backup.

Other capsule designs typically don't have those sorts of options. They
typically have three parachutes and say they're redundant because they
can land using two without killing the crew. Why don't you research
what Boeing is going to use since their "Starliner" will fly alongside
Dragon to/from ISS.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In article om,
says...

On 2016-01-07 07:38, Fred J. McCall wrote:

You need to stop comparing Dragon V2 and Soyuz. It's like comparing
apples and aardvarks.

Both designed to land on land.
Both have engines designed to cushion the landing.

By your logic a Piper Cub and a C-17 can also be directly compared since
they both are aircraft which are designed to land on a runway and they
both have landing gear with wheels to cushion the landing.

Sorry, but that is bull$hit and I'm officially calling you on it.


So yeah, Dragon can use engines instead of parachutes, but I am
talking
about the final seconds prior to touch down.

The final seconds are *completely* different. Super Dracos can
differentially throttle and are computer controlled to bring the
velocity of the capsule as close to zero as possible when landing.
Soyuz has a radiation emitter which triggers a radiation sensor (due to
backscatter from the radiation hitting the ground) which fires *solid
fuel* braking rockets which *can't* be throttled AT ALL!

You're woefully ignorant about how these two capsules land, which can be
cured by reading up on the details. Even Wikipedia would be a good
start!

Let me ask you this: in the NASA tests, will Dragon land on water
without any use of its engines to act as retro rockets to smooth the
landing ? Or will it do like other NASA capsules and fall flat on its
belly at parachute speeds ?

That test has already been done, and Dragon V2 passed. Why don't you
watch the abort test videos and read the articles written about the test
instead of asking here?

Considering that the capsule is nominally designed to land smoothly on
legs on flat terrain and that NASA might want a hard landing on water,
does that mean that Space-X will need to change its seat designs ?

Why? It already passed the abort test which included a water landing
under parachutes.

Will it require special custom made seat liners like on Soyuz ?

Require is a strong word which depends on who is writing the rules.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On 1/7/16 8:09 PM, Jeff Findley wrote :
In article om,
says...

Let me ask you this: in the NASA tests, will Dragon land on water
without any use of its engines to act as retro rockets to smooth the
landing ? Or will it do like other NASA capsules and fall flat on its
belly at parachute speeds ?

That test has already been done, and Dragon V2 passed. Why don't you
watch the abort test videos and read the articles written about the test
instead of asking here?

This is a perfectly suitable place to asks questions about space related
technology. If you don't want to answer the question just don't answer.
But asking questions here is just great.


Alain Fournier

"Jeff Findley" wrote in message
...

In article m,
says...

You might want to look at the accuracies for previous capsule
programs
(Mercury/Gemini/Apollo).


You got me wondering, so I went to Wikipedia and looked at Apollo data
(there's more there, but I figured I'd ignore the earlier stuff).

If I did my math correctly the average for Apollo was within 3.3km of their
target with a 1st standard deviation of 3.81.

However, those numbers appear to be really skewed by Apollo 4 (missed by
16km).
Take that out and you get 2.3km and 1.17km.

So not quite a parking lot, but a decent sized field in Texas.

That said, given that those were unpowered descents and I believe there was
no steering capabilities under the shoot, I feel confident in thinking that
Dragon V2 can do better.

(note, the data didn't show anything for the Skylab flights, but did for
ASTP, so I included that. I'm sure the Skylab data is out there, but I'm
being lazy tonight.)


My concern isn't about the accuracy and predictability of a single
landing, it is with regards to how much landing spot varies every time a
Dragon falls out of the sky.

So look at the data from *all* the previous capsule landings and do the
math. It's not that hard.

In other words, if you have 20 landings from ISS and mark a spot for
each, how much of an area will that represent ? the size of DC or the
size of Texas ?


DC is 10 miles on a side. So you could probably land somewhere in the
National Mall with some accuracy.

My guess is that it would be smaller than either of those, and that was
with unguided parachutes for the terminal phase. Using the variable
thrust Super Dracos will give positive control over the terminal phase.


That's my guess too.

Jeff

--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

In article , says...

On 1/7/16 8:09 PM, Jeff Findley wrote :
In article om,
says...

Let me ask you this: in the NASA tests, will Dragon land on water
without any use of its engines to act as retro rockets to smooth the
landing ? Or will it do like other NASA capsules and fall flat on its
belly at parachute speeds ?

That test has already been done, and Dragon V2 passed. Why don't you
watch the abort test videos and read the articles written about the test
instead of asking here?

This is a perfectly suitable place to asks questions about space related
technology. If you don't want to answer the question just don't answer.
But asking questions here is just great.

So you want to be spoon fed recent news which is readily available for
free on most space news websites? You do know this newsgroup is nearly
dead, don't you? Why not try gathering general info from other sites
before asking here? Your questions will no doubt be better for it and
what is left of this group will be better for it as well.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On Thursday, JF Mezei pointed out that ...
On 2016-01-07 23:15, Jeff Findley wrote:

free on most space news websites? You do know this newsgroup is nearly
dead, don't you?


Insulting people telling them to stop using the newsgroup to learn from
people who know doesn't help keep the newsgroup alive. You have the
choice to keep the knowledge to yourself and stay silent.

It would be an appropriate use of the newsgroup to ask for pointers to
articles and references.

What used to be a strength of the group was the number of references
that were discussed. That involves someone /looking outside the group/
for information, and /bringing it back/ to discuss with the rest of us.

/dps

--
Ieri, oggi, domani

In article ,
says...
You got me wondering, so I went to Wikipedia and looked at Apollo data
(there's more there, but I figured I'd ignore the earlier stuff).

If I did my math correctly the average for Apollo was within 3.3km of their
target with a 1st standard deviation of 3.81.

However, those numbers appear to be really skewed by Apollo 4 (missed by
16km).
Take that out and you get 2.3km and 1.17km.

So not quite a parking lot, but a decent sized field in Texas.

I vaguely remember these numbers coming up in early sci.space
discussions during capsule versus lifting body or winged spacecraft
debates (i.e. some people thought we "needed" the cross range of the
shuttle). I've always thought those numbers were quite impressive given
that Apollo's terminal descent was under *unguided* circular parachutes.

Replace those Apollo era parachutes with a very large para-foil (which
NASA's X-38 lifting body was testing) or a powered vertical descent
(which Dragon V2 will be testing), and you should be able to perform a
"pinpoint" landing as long as your design includes something like 5 to
10 km of cross-range capability (using your numbers plus a factor of
safety).

You'd also want to monitor winds at the descent and landing site
carefully. The nice thing is that KSC and/or Cape Canaveral already
closely monitor wind profiles from sea level to relatively high
altitudes in order to support launches (very long, thin, launch vehicles
have wind constraints to minimize bending loads on the vehicle while in
the dense atmosphere). Doing the same for landings shouldn't be that
big of a deal. One would think the cost involved in doing that would be
less than the cost of the support ship(s) needed for a "splashdown" in
the ocean.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer