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TURIN
11th Oct 2018, 10:27
Booster failure apparently.

https://www.nasa.gov/nasalive

Both occupants landed safely by all accounts.

Is this a first? I can't remember anything like this happening since the Mercury flights.

eckhard
11th Oct 2018, 10:43
A Gemini Titan aborted on the pad. I think it was Wally Schirra? He kept his cool and didn’t use the escape rocket, thus saving the mission.

wiggy
11th Oct 2018, 10:54
There has been a previous Soyuz abort during launch, can’t remember the details but as I recall it the crew had a ballistic very high “g” re-entry which may have led to injuries...will check for details later..

As far as Gemini - Schirra and Stafford, Gemini 6...pad abort ..everything happened as planned including the clock starting but there was no sustained ignition and no real liftoff (fortunately).

For various reasons Gemini used ejection seats rather than the escape rockets used on Mercury/Apollo and Soyuz...and there was some disquiet in Astronaut Corp about the system. Since the crew were sat in a pure oxygen environment prior to launch there was a theory that in the event of an ejection the crew would depart the spacecraft in the fashion of Roman candles....

TURIN
11th Oct 2018, 11:06
Just checked Wikipedia and apparently, Soyuz 18A in 75 and Soyuz 33 in 79 did safe ballistic returns after launch booster failures.

wiggy
11th Oct 2018, 12:18
Ah thanks..knew there had been one previous but wasn’t aware were there had been two.

eckhard
11th Oct 2018, 12:42
Thanks for the details Wiggy. Of course; Gemini used ejection seats and not an escape tower.

er340790
11th Oct 2018, 17:04
I believe the two crewmen pulled around 6G on the return. Substantial, but nothing like the limits the human body can withstand for short periods.

They both seemed pretty healthy on their walk after pick-up too.

That said, I suspect the cosmodrome cleaners may find the state of the WCs somewhat more challenging... :eek:

Mac the Knife
11th Oct 2018, 17:24
Musta pulled a lot of G on the way down...

Way to go!

tartare
11th Oct 2018, 23:32
Can one of you eminently knowledgeable lot explain to me how all these G's are generated that I hear about in ballistic recoveries?
Presumably if there's a problem on the ascent - the escape tower needs to generate thrust to depart and clear the already ascending rocket - therefore extra G's generated for the cosmonauts as it climbs away. (who are already under a 4g load anyway)
Said escaping capsule then probably follows a parabolic arc (am I right) and re-enters at a steeper angle than it might normally - thus subject to much harsher atmospheric braking - hence more Gs?
Or am I missing something?

EDIT: Hmmm - answered my own question.
https://www.popularmechanics.com/space/rockets/a23721153/astronauts-ballistic-mode-emergency-landing/
Rolling for stability, and slowing down real fast with little outside reference.
4.5gs was enough for this lad - 7-8g with the above force vectors does not sound like fun.

tdracer
12th Oct 2018, 00:22
There has been a previous Soyuz abort during launch, can’t remember the details but as I recall it the crew had a ballistic very high “g” re-entry which may have led to injuries...will check for details later..

As far as Gemini - Schirra and Stafford, Gemini 6...pad abort ..everything happened as planned including the clock starting but there was no sustained ignition and no real liftoff (fortunately).

For various reasons Gemini used ejection seats rather than the escape rockets used on Mercury/Apollo and Soyuz...and there was some disquiet in Astronaut Corp about the system. Since the crew were sat in a pure oxygen environment prior to launch there was a theory that in the event of an ejection the crew would depart the spacecraft in the fashion of Roman candles....


I've been reading Gene Kranz's book (Failure Is Not An Option - which BTW he never actually said - it was an invention by Ron Howard for the Apollo 13 movie, but Kranz liked it so much he adopted it).
According to the book, Gemini 6 pad abort was because as the engines powered up, the vibrations knocked one of the umbilicals off prematurely which triggered the engine shutdown. Turned out it was a blessing in disguise - they later discovered a dust cover that hadn't been removed during engine assembly, so there would have been an engine failure as they left the pad which would have been catastrophic.

As for the ejection seats - I read somewhere (a long time ago) that ejection seats were used instead of an escape tower because the Titan fuel was not as explosive as the liquid oxygen/kerosene fuel used in the first stage of the Redstone, Atlas, and Saturn rockets. However the ejection seats would not have been as effective for an abort on or close to the ground as the escape tower system.

ORAC
12th Oct 2018, 06:54
The first 2 Space Shuttles (Enterprise And Columbia) were fitted with flight deck ejector seats as well for 6 flights, intended for the early missions when they had a crew of only two (STS-1 to 4). On the later flights when additional crew were carried (STS-5 and 9) the mission commanders elected to have the seats disabled for ethical reasons.

The seats were removed during maintenance before any further flights were flown.

wiggy
12th Oct 2018, 07:53
Tartare

With pure ballistic as the article states you fly the parabola the dynamics dictate and you get the g" onset and "g" values you are given, so to speak.

If you can fly a non-ballistic lifting rentry (Gemini, Apollo, Shuttle) then you can use lift to flatten the descent arc, reduce the rate of descent into the lower thicker atmosphere and therefore reduce the onset of high g-levels or even reduce peak g by spreading the loading over a longer period of time.

td

As for the ejection seats - I read somewhere (a long time ago) that ejection seats were used instead of an escape tower because the Titan fuel was not as explosive as the liquid oxygen/kerosene fuel used in the first stage of the Redstone

Yep, the belief was if the Titan went Tango Uniform you got a fast burn of escaped propellants and oxider, rather than a genuine explosion, therefore in theory seats would be adequate....

As for the Shuttle.,,yes, seats on the early flights but again there were some who expressed doubts about their usefulness in a launch abort...for example it was reckoned ejecting with the main engines still running would probably mean the ejectee(s) being exposed the the main engine and/or Solid Rocket Booster exhaust plumes...

Less Hair
12th Oct 2018, 08:21
Is the capsule made to spin on a ballistic descend in order to stabilize it? How fast is it turning then? Is the "splashdown" in the tundra the same as on a regular landing or somehow limited in comfort again?

tescoapp
12th Oct 2018, 08:43
yes its spins, don't know how fast, same principle as a rifle bullet rotating, its to keep the heat shield pointing in the right direction.

I presume things are the same as normal after the parachute is deployed.

By all accounts I have read from Tim Peak and Scott Kelly the splashdown is pretty lively but not too bad.

Scott Kellys book Endurance has some good info on the departure and recovery plus post flight procedures. It doesn't go into huge depth or heavy engineering but its enough that its was interesting for me as an engineer and the Mrs actually seemed to grasp concepts of what he was saying (she is languages) which is no mean feat in my experience.
Hopefully Scott will write a book on electricity and how thermostats work for linguistic types. For 10 years now I have been trying to educate her in the fact that turning the thermostat to max doesn't actually heat the place up quicker and the neutral stays live when you turn a light switch off.

tartare
12th Oct 2018, 10:29
Oi - A Van - can you offer a Russian perspective please comrade...

Tankertrashnav
12th Oct 2018, 11:07
I see a "criminal investigation" is being reported. I wonder if they are talking criminal incompetence, or something more sinister.

arketip
12th Oct 2018, 11:15
Oi - A Van - can you offer a Russian perspective please comrade...

Why did they not use one of those better, faster and more reliable US transport system?

tescoapp
12th Oct 2018, 11:40
have you got any links to the criminal stuff tanker?

The first thing that went through my head when I saw it after the hole in the service module was if there was sabotage element.

And if they catch someone we more than likely won't hear about it. It will just be a .22 in the back of the head in a field.

wiggy
12th Oct 2018, 12:23
Less hair

Is the "splashdown" in the tundra the same as on a regular landing or somehow limited in comfort again?

Splashdown was a bit of an American thing, The Russians have always landed their manned spacecraft on dry land by choice and so their landing techniques/systems are designed with that mind (e.g. Soyuz has retrorockets that fire just before touchdown to reduce the rate of descent...). The landing from the abort the other day would have effectively been a normal Soyuz landing.


Spin rate:

Don’t have the numbers but we are not talking rifle bullet rates - for example when things went badly wrong with the main attitude control system on Gemini 8 the roll rate got up to around 300 degrees per second and that was regarded as being close to human tolerance so you’d expect the routine rates to be significantly less than that: FWIW here’s window footage from a Gemini re-entry..

https://m.youtube.com/watch?v=1Gyn8Fx2Bfs

FWIW many modernish capsules direct their inherent lift vector by rolling....(you can’t kill the lift vector, it’s a consequence of capsule shape and position of centre of gravity), so sometimes the rolling is done as much to null out steering as to ensure stability.

KenV
12th Oct 2018, 16:44
yes its spins, don't know how fast, same principle as a rifle bullet rotating, its to keep the heat shield pointing in the right direction.Yes, the capsule spins, but no, not not to keep it stable and pointing in the right direction. Remember that the capsule's mass is not symmetrical around its longitudinal axis. If you spun it quickly it would wobble and become unstable rather than stable. Rather, spin in one direction slightly increases lift and spin in the opposite direction decreases lift. The direction and speed of spin are constantly adjusted to keep the capsule on the optimum trajectory (think "glidepath" on an ILS approach). The spin has a secondary benefit as it creates a force vector normal to the lift vector. In other words, it can be used to adjust/correct the track (think track centerline or localizer on an ILS approach).

During ballistic reentry, the spin rate is increased, but again, not to provide spin stabilization. The off-center CG of the capsule would make spin stabilization effectively impossible. During ballistic reentry there is no lift (the capsule's angle of attack is very high and effectively is stalled). But the CG of the capsule is not located along the geometric centerline of the capsule. This asymmetry results in a force vector normal to the trajectory, resulting in a slightly curved trajectory, resulting in a touchdown far from the intended point. Spinning the capsule results in the off center CG being constantly moved around the longitudinal axis of the capsule, effectively cancelling out the curve. So technically the resulting trajectory is a mild helix.

Hope this clarified.

tescoapp
12th Oct 2018, 17:09
Same principle as a cricket ball then.

Thanks for that.

megan
13th Oct 2018, 05:03
Couple of NASA papers on the subject, video also provides insight.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060020180.pdf

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670027745.pdf

https://www.youtube.com/watch?v=ix5SzrPdS7U

tartare
13th Oct 2018, 07:45
Fascinating film - I had no idea there was that degree of control over the capsule as it re-entered.
I knew they had to hit a very narrow window to avoid skipping right off the atmosphere, but interesting there was that degree of cross and downrange control.
My awe at and admiration of what those guys did with primitive computers and slide rules is only increased...

Hokulea
13th Oct 2018, 07:59
Same here. I didn't realise they actually did what was essentially two re-entries if I understand things correctly, the second leading to the ballistic trajectory.

wiggy
13th Oct 2018, 13:38
Fascinating film - I had no idea there was that degree of control over the capsule as it re-entered.
I knew they had to hit a very narrow window to avoid skipping right off the atmosphere, but interesting there was that degree of cross and downrange control...

It actually got too accurate...up to and including Apollo 8 they basically aimed for the middle of the recovery fleet. When Apollo 8’s (“C prime” in NASA speak) command module overflew the recovery carrier in the dark and landed a bit close for comfort to the deck letters were written very strongly suggesting having the centre of the recovery fleet as the target point was not a good idea. The following was written by one of the legends of Mission Control “Bill” Tindall...

”....I've done a lot of joking about the spacecraft hitting the aircraft carrier, but the more I think about it the less I feel it is a joke. There are reports that the C Prime command module came down right over the aircraft carrier [stationed at 165 degrees 02.1' west longitude and 8 degrees 09.3' north latitude] and drifted on its chutes to land [at 165degrees 1.02' west and 8 degrees 07.5' north, only 4,572 meters] away. This really strikes me as being too close. . . . The consequence of the spacecraft hitting the carrier is truly catastrophic. . . . I seriously recommend relocating the recovery force at least [8 to 16 kilometers] from the target point.”

radeng
13th Oct 2018, 13:53
In the NASA TV clip, every few seconds in the background there are the Morse characters AN sent three times. Anybody got any idea what that is for?

hiflymk3
13th Oct 2018, 14:02
In the NASA TV clip, every few seconds in the background there are the Morse characters AN sent three times. Anybody got any idea what that is for?
Anyone got Novochoc?

ORAC
13th Oct 2018, 14:46
Interestingly I found the following. Was it a joint agreed emergency standard even back in the early days of the space race, or started by NASA and adopted for the Soyuz?

"HF is still used on late model Soyuz spacecraft during the recovery phase, when Morse code (the Morse-code characters AN) and AM voice can be transmitted on 18.060 MHz. Morse code beacon (AN) only is transmitted on 8.364 MHz during recovery operations. The antenna is a whip antenna that is stored as a rolled-up steel band under a little door in the upper part of the re-entry vehicle"

Soyuz Radio Systems (http://www.svengrahn.pp.se/histind/Soyuz1Land/SoyRadio.htm)

tdracer
14th Oct 2018, 00:04
Splashdown was a bit of an American thing, The Russians have always landed their manned spacecraft on dry land by choice and so their landing techniques/systems are designed with that mind (e.g. Soyuz has retrorockets that fire just before touchdown to reduce the rate of descent...). The landing from the abort the other day would have effectively been a normal Soyuz landing.
That goes back to the very beginning of the 1960s space race. The USSR had massive sparsely populated land areas to use for spacecraft recovery - the USA not so much. Further, due to where the US launch site was located (and unlike the Russian launch site), if there was a launch abort, a water recover was the only option (and for the first Mercury/Redstone missions, they simply did not have sufficient range for other than a water recovery).

With the current plans to re-use the manned capsules, the US is moving towards planned land recovery - since saltwater isn't exactly kind to spacecraft systems. The Boeing 'Starliner' manned capsule design it intended to come down on land, using airbags deployed right before touchdown to cushion the landing.

wiggy
14th Oct 2018, 07:25
Indeed td that was indeed the Soviet theory...mind you even the best laid plans.........

On 16 October, Soyuz 23 returned to earth and landed 8:45 p.m. local time, but weather conditions were poor and the cosmonauts experienced an unusual recovery. They landed on a freezing Lake Tengiz (https://en.m.wikipedia.org/wiki/Lake_Tengiz) (average depth 2.5m, max depth 6.7m), 8 km from shore, in the middle of a blizzard, with fog and temperatures at −22 C.[3] (https://en.m.wikipedia.org/wiki/Soyuz_23#cite_note-newkirk-3) It was the first water landing by a Soviet crew.[4] (https://en.m.wikipedia.org/wiki/Soyuz_23#cite_note-clark-4) The capsule was designed to land in any conditions, even in a body of water, so the only concern was the increased difficulty in finding the capsule and crew.[3] (https://en.m.wikipedia.org/wiki/Soyuz_23#cite_note-newkirk-3)

The parachute quickly filled with water and dragged the capsule and its crew beneath the surface, in addition an electrical short caused by water impact caused the reserve parachute to accidentally deploy. The capsule cooled in the freezing water, and the cosmonauts removed their pressure suits and donned their normal flight suits, expecting a quick rescue. The parachutes became waterlogged and pulled the capsule onto its side, preventing the hatch from being opened. The transmission antennas were also under water, so the crew could not communicate with rescue teams........


If you think that’s bad it got even better in a :eek: sort of way but I won’t spoil the ending, the full account is here:


https://en.m.wikipedia.org/wiki/Soyuz_23

SOPS
14th Oct 2018, 08:34
I have been an Apollo tragic since a very young age...I watched the moon landing at school. I thought I knew quite a bit..but I admit I have learnt a lot from this thread!