Author Topic: GSLV MkII & cryo stage discussion thread  (Read 38240 times)

Offline sanman

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #40 on: 01/08/2014 04:55 PM »
Hmm, so it doesn't have the restart capability yet? Is that planned for the future?

Likewise, if thrust is improved upto 90kN, are there any plans to take it higher - like say, to 100kN?

Offline cave_dweller

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #41 on: 01/09/2014 08:56 AM »
What does it take to achieve restart capability in the space?
what modifications are needed to attain 9 ton ?

I believe this is a fairly complex and expensive problem. An additional ignition setup would mean additional complexity and weight. Also, there is a problem of "boiling off" due to resulting increased volume during burn offs.

That is, if you run the motor for 60 seconds. And shut it off, you'll have to compensate for the volume evacuated by that 60 seconds of fuel. Which would mean the cryogenic setup would have to further cool the propellants to maintain fuel density for appropriate flow mass rate or nominal thrust when re-ignited.

This issue also exists when the engine doesn't have to be restarted. But I believe is handled by the turbo pump. And results in gradual loss of thrust and is acceptable when executing a full burn.

Hypergolic fuels are better suited for in-space applications (orbital maneuvers etc). Since they do not need to be cooled to maintain fuel density and also because they do not need an additional ignition setup. Hypergolic fuel and oxidizer auto-ignite on contact.



 

Offline cave_dweller

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #42 on: 01/09/2014 09:06 AM »
Hmm, so it doesn't have the restart capability yet? Is that planned for the future?

Likewise, if thrust is improved upto 90kN, are there any plans to take it higher - like say, to 100kN?

I think it should be easy to increase the thrust simply by using engine clusters.
However the problem may be one of maintaining the aero-dynamic and weight character of the flight.
Which should again be fairly straight forward.

I think the biggest mystery of cryogenic engines are fuel tank material science (weight vs strength) and turbo and turbo booster pump design and materials.


Offline antriksh

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #43 on: 01/09/2014 12:30 PM »
Hmm, so it doesn't have the restart capability yet? Is that planned for the future?

Likewise, if thrust is improved upto 90kN, are there any plans to take it higher - like say, to 100kN?

Restart capability will be on CE20's upgraded versions. That wont be required if LVM3 is ready by 2017-2018.
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Offline sanman

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #44 on: 01/14/2014 04:32 AM »
Restart capability will be on CE20's upgraded versions. That wont be required if LVM3 is ready by 2017-2018.

I don't understand - CE20 is the cryo engine stage for LVM3, isn't it?
So you're saying the later versions of it will have restart capability, as part of the LVM3 launch stack.
Why won't CE20 restart capability be required if LVM3 is ready by 2017-18?

Also, I was looking at this:

http://www.b14643.de/Spacerockets_1/India/GSLV/Gallery/GSLV-2_D5.htm





It says "In development: Payload Assist Modul (PAM-G) for direct injection to orbit"
So in what circumstances is it used and why?

EDIT: I found mention of it from you in another thread:

http://forum.nasaspaceflight.com/index.php?topic=30037.msg1003555#msg1003555

Still - what does direction injection into orbit mean? I thought everything gets directly injected into orbit. You mean like without any orbit-raising maneuvers required?
« Last Edit: 01/14/2014 04:41 AM by sanman »

Offline rnataraja

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #45 on: 01/14/2014 04:33 AM »
Regarding the chicken-and-egg hurdle, I wonder if ISRO could have progressed faster by engineering a cryogenic engine based on LCH4 instead of LH2? At least LCH4 has an industrial base to support it, unlike LH2, and so moving in that direction isn't a leap out into empty space like LH2 is.

Even with the planned RLV/TSTO, they should still consider LCH4, because of its high Isp, and plus it's not as hard to work with as LH2.



At a broader level than described here. How well has private industry aspired to support the ISRO's efforts in India? What is missing in them today?
If someone who was inspired(like me) by the grand but secret univers and space, and are very serious about satisfying the desire by contributing to advancements and be part of an aspiring private industry. What is a good area?

Offline ss1_3

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #46 on: 01/14/2014 02:51 PM »

Still - what does direction injection into orbit mean? I thought everything gets directly injected into orbit. You mean like without any orbit-raising maneuvers required?

Most certainly, they are referring to direct injection into GEO orbit as against the current capability of launching payload into GTO first and then performing on board engine burns to get into GEO.

Offline antriksh

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #47 on: 01/14/2014 03:30 PM »
Restart capability will be on CE20's upgraded versions. That wont be required if LVM3 is ready by 2017-2018.

I don't understand - CE20 is the cryo engine stage for LVM3, isn't it?
So you're saying the later versions of it will have restart capability, as part of the LVM3 launch stack.
Why won't CE20 restart capability be required if LVM3 is ready by 2017-18?



Sorry I didnt put it clearly. CE7.5 wont have restart capability, but CE20 will have that in its upgraded version (not the one that will be demonstrated in 2016-17)

Restart capability will be on CE20's upgraded versions. That wont be required if LVM3 is ready by 2017-2018.


It says "In development: Payload Assist Modul (PAM-G) for direct injection to orbit"
So in what circumstances is it used and why?


Still - what does direction injection into orbit mean? I thought everything gets directly injected into orbit. You mean like without any orbit-raising maneuvers required?

Yep no orbit raising maneuver by the satellite.
« Last Edit: 01/14/2014 03:32 PM by antriksh »
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Offline johnxx9

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #48 on: 01/14/2014 04:51 PM »
Some interesting tidbits!

It's from 2009. One change is that even the basic MkII configuration has flown with 40 tons of propellant in the second stage.

Offline sanman

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #49 on: 01/14/2014 08:42 PM »
What does this Payload Assist Module (PAM) use? What fuel is it based on? What engine does it use - something like Liquid Apogee Motor? So it's like an uppermost stage, but it's not cryogenic - or is it? Why use a non-cryo engine on top of a cryo engine stage? That would make no sense, unless it's meant for deferred use and needs to avoid boil-off.

Offline johnxx9

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #50 on: 01/15/2014 07:05 AM »
What does this Payload Assist Module (PAM) use? What fuel is it based on? What engine does it use - something like Liquid Apogee Motor? So it's like an uppermost stage, but it's not cryogenic - or is it? Why use a non-cryo engine on top of a cryo engine stage? That would make no sense, unless it's meant for deferred use and needs to avoid boil-off.

It'll be used for MEO missions,  to place navigation satellites directly into 19,000km circular orbit. It is derived from the upper stage of PSLV. It's been in development for some time. Uses hypergolic propellants.

Heres it being tested.

« Last Edit: 01/15/2014 07:06 AM by johnxx9 »

Offline sanman

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #51 on: 01/15/2014 05:01 PM »
So since MEO is less than the GTO that the Cryogenic Upper State can deliver to, then why use this PAM along with the Cryogenic Upper Stage? It sounds like you'd want to use this PAM thing in lieu of the Cryogenic Upper Stage, if you're only trying to reach MEO. Or maybe this PAM thing can boast your payload capacity to MEO and GEO?

Can this PAM thing help with BEO missions to the Moon or Mars, etc?
I wonder what kind of lift capacity it can give to these places.

Although it seems rather strange to me that you'd use a liquid hypergolic stage on top of a lighter cryo stage. Doesn't that sort of defeat the purpose of having a cryo stage? What does the liquid hypergolic stage give you that the cryo stage doesn't?


Offline Lars_J

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #52 on: 01/15/2014 07:13 PM »
Although it seems rather strange to me that you'd use a liquid hypergolic stage on top of a lighter cryo stage. Doesn't that sort of defeat the purpose of having a cryo stage? What does the liquid hypergolic stage give you that the cryo stage doesn't?

Hypergolic systems are easier to make long endurance stages from. They don't need to be cooled, they are easier to ignite. This is useful for final orbit insertion several hours or days into the mission. Most hydrogen cryogenic stages have a lifetime of a few hours at most.

Offline sanman

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #53 on: 01/15/2014 08:19 PM »
Ahh, so this hypergolic stage is meant for deferred use.

So if you were designing a lunar lander, would that likewise be done best as hypergolic too?

Offline baldusi

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #54 on: 01/16/2014 12:10 AM »
Although it seems rather strange to me that you'd use a liquid hypergolic stage on top of a lighter cryo stage. Doesn't that sort of defeat the purpose of having a cryo stage? What does the liquid hypergolic stage give you that the cryo stage doesn't?
The current CE-7.5 engine can't restart. And for circularization (be it GSO or MEO) you'd need at least the circularization burn. And  i doubt that the Cryo stage has more than a couple of hours of life. Hypergolics are storable and can make multi hour missions.

Offline Lars_J

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GSLV D5 (MkII) & cryo stage discussion thread
« Reply #55 on: 01/16/2014 03:21 PM »
Ahh, so this hypergolic stage is meant for deferred use.

So if you were designing a lunar lander, would that likewise be done best as hypergolic too?

Yes. I think all lunar landers (manned and unmanned) have been hypergolic.

There have been proposals for cryogenic landers (Altair), but even then the ascent stage has been hypergolic.
« Last Edit: 01/16/2014 03:24 PM by Lars_J »

Offline cave_dweller

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #56 on: 01/16/2014 07:52 PM »
Ahh, so this hypergolic stage is meant for deferred use.

So if you were designing a lunar lander, would that likewise be done best as hypergolic too?

Yes. I think all lunar landers (manned and unmanned) have been hypergolic.

There have been proposals for cryogenic landers (Altair), but even then the ascent stage has been hypergolic.

Are hypergolics easier to store in space than LOX+LH2?

How do hypergolics react to the extreme temperatures of space?
And how do cryogenics react?

How are they sheltered (if at all)? Always keep it oriented away from Sun?
How do they manage to isolate "hot" components from "cold" components of the space craft?



Offline Lars_J

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #57 on: 01/16/2014 07:57 PM »
Ahh, so this hypergolic stage is meant for deferred use.

So if you were designing a lunar lander, would that likewise be done best as hypergolic too?

Yes. I think all lunar landers (manned and unmanned) have been hypergolic.

There have been proposals for cryogenic landers (Altair), but even then the ascent stage has been hypergolic.

Are hypergolics easier to store in space than LOX+LH2?

How do hypergolics react to the extreme temperatures of space?
And how do cryogenics react?

I'm no expert, but cryogenics obviously have to be kept cold. Hypergolics are less sensitive, but you still have to prevent them from freezing or becoming too hot. It is just an easier temperature range to manage through use of insulation and heaters. So yes, easier to store in space.

http://en.wikipedia.org/wiki/Hypergolic_propellant
« Last Edit: 01/16/2014 08:02 PM by Lars_J »

Offline sanman

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #58 on: 01/16/2014 10:14 PM »
In some thread someone commented that cryogenic restart capability is impinged upon by the fact that when you burn off some of your cryo propellants, some of the remaining propellants will be more likely to go into vapor phase. Has anybody ever tried a bladder approach, whereby the propellant container shrinks in volume to keep the remaining propellant compressed? Obviously the elastic force of your bladder has to exceed the vapor pressure of the volatile.

Offline vyoma

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Re: GSLV D5 (MkII) & cryo stage discussion thread
« Reply #59 on: 01/17/2014 01:13 AM »
In some thread someone commented that cryogenic restart capability is impinged upon by the fact that when you burn off some of your cryo propellants, some of the remaining propellants will be more likely to go into vapor phase. Has anybody ever tried a bladder approach, whereby the propellant container shrinks in volume to keep the remaining propellant compressed? Obviously the elastic force of your bladder has to exceed the vapor pressure of the volatile.

Centaur upper stage uses stainless steel balloon tank, which doesn't have any structural integrity on its own. LH2/LOX are pumped to keep balloons inflated.

But, I guess restart capability is achieved a bit differently. There are  two problems to solve during cryo restart:
1) Vapors in tanks and fuel lines, which expand rapidly and can damage tanks.
2) In zero-g, liquid LH2/LOX will be "floating" in tanks. So when engine is restarted, fuel may not flow into fuel lines and turbopumps.

To address these issues before restart:
1) Centaur vents vapors into Space, before starting main cryo engine. This results in some loss of fuel.
Quote
... we are going to take this Atlas valve, scale it down a little bit, mount the same valve on the liquid hydrogen tank as the liquid oxygen tank, and we’re going to command the valve to open when you have to vent.
Quote
The solution was to design a vent fin or snout on the nose fairing that extended about 50 inches from the tank, just far enough away to keep the hydrogen gas from igniting along the hot surface of the vehicle.

2) Centaur uses small conventional rocket motors (H2O2 powered ullage rockets) to accelerate a bit in order to settle down "floating" liquid fuel at the bottom of tanks. This makes sure that fuel indeed flows into fuel lines when main cryo engine is restarted.
Quote
The new knowledge of the ullage area also led to greater confidence in managing the propel-lants during the coast phase. A Reaction Control System (RCS) was designed to provide acceleration just before venting. The system consisted of a hydrogen peroxide supply bottle, lines, valves, and small vernier motors called thrusters. Before the tank pressure reached a certain point, small thrusters in the tank were fired to reposition the propellants in the aft end of the vehicle.

Then a valve could be opened to relieve pressure without danger of loss of liquid propellant. The same thrusters were fired in preparation for starting the engine, so that liquid rather than gaseous hydrogen and oxygen entered the pumps.

Sources:
http://history.nasa.gov/SP-4230.pdf
http://www.spacelaunchreport.com/aclv3cb.html

I guess balloon tanks might also help in keeping fuel settled down, by deflating when fuel is consumed (speculating).
« Last Edit: 01/17/2014 01:50 AM by vyoma »

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