GSLV-D5 Launch status and post launch discussions

member_28108 · Post by **member_28108** » 05 Jan 2014 17:40

Luckily on DD they showed the screen with flight data most of the time. I had on one TV NDTV which was showing the launch from afar (We could see it till first stage separation) and Doordarshan so it was a good mix.

Brando · Post by **Brando** » 05 Jan 2014 17:40

The current CE7.5 is a staged combustion cycle engine. The CE20 that is to be part of the GSLV MK3 is supposed to be a gas-generator cycle engine. Does anybody know why they changed technologies especially when staged combustion cycle is more efficient ?

member_28348 · Post by **member_28348** » 05 Jan 2014 17:47

vina wrote:BRILLIANT . This is a FU AMERICA launch.

They tried blocking India's path in science and technology by blocking the Russian ToT for the cryogenic stage (while themselves getting the RD-180 stage , lock stock and barrel including full manufacturing rights).

ISRO has given them the birdie and told them to STFU. Fat lot of good that tech denial did to them.

Very proud moment indeed for India.

And quake in your Mao trousers Chinese drones. This is a staged combustion variable thrust engine with restart capability, the pinnacle of tech. The CHinese cryogenic engines are gas generator cycles, a level down in technology and complexity.

WOW really? chinese cryogenic engines might be more powerful but ours are technologically more advanced?

krisna · Post by **krisna** » 05 Jan 2014 17:48

yipeeee. what a way to get up---
congrats ISRO for making the naughty kid well behaved.
surely coolest hot engine.
colorful lungi dance with choicest gaalis to its enemies.

member_28108 · Post by **member_28108** » 05 Jan 2014 17:49

Gas generator cycle technology is cheaper though less efficient. The US used staged combustion type but they now also use gas generator ones which they got from Russia as the costs are considerably less.

member_23694 · Post by **member_23694** » 05 Jan 2014 17:50

at the time of cryo stage ignition it was specifically mentioned ... no clapping for some time

However this cryo stage did not perform any manouvers etc, which is fine. Hope we see more variations
during flight in the future launches
what are the next launches scheduled for 2014, MK.3 etc, Timelines please
Did not have enough of GSLV so need a few more launches this year

K Mehta · Post by **K Mehta** » 05 Jan 2014 17:54

Get ahead and keep going!

Kakarat · Post by **Kakarat** » 05 Jan 2014 17:59

ISRO FB:
Relive those glorious moments when ‪#‎India‬'s ‪#‎GSLV‬ D5 powered by the Indigenous ‪#‎cryogenic‬ stage blasted off to create history. Relish the entire launch video here.
http://webcast.isro.gov.in/

vina · Post by **vina** » 05 Jan 2014 18:05

prasannasimha wrote:Gas generator cycle technology is cheaper though less efficient. The US used staged combustion type but they now also use gas generator ones which they got from Russia as the costs are considerably less.

You couldn't be more wrong and you have got it backwards. The issue is not cost,but engineering complexity and difficulty. The US considered the oxygen rich staged combustion cycle "impossible" and went for the fuel rich gas generator cycle which is less efficient because of pumping losses.

It is the Russians who perfected the oxygen rich staged combustion cycle for their NK-33 engine and it's derivative is the RD-180 which the Americans use as their main stage for nearly all their launch vehicles now (Atlas etc) which is imported from Russia.

Anyways, that is another topic which you can see for yourself online.

Today, we have a staged combustion variable thrust engine that has a high specific impulse and is as good as any of the best out there (when it is grown to full potential, can be the best ), in fact better than the Russian KVD-1 stage that it replaced, which when we are talking of rocket engines is a tremendous achievement indeed. So enjoy the moment.

member_23694 · Post by **member_23694** » 05 Jan 2014 18:16

^^^^^^^^^^^^^^^^
So if staged combustion is better than gas-generator cycle engine then why move to an inefficient tech for CE - 20 when
we have mastered staged combustion in CE 7.5 ? Any pointers please for the reason ISRO moved to gas-generator cycle engine

Kakarat · Post by **Kakarat** » 05 Jan 2014 18:20

dhiraj wrote:^^^^^^^^^^^^^^^^
So if staged combustion is better than gas-generator cycle engine then why move to an inefficient tech for CE - 20 when
we have mastered staged combustion in CE 7.5 ? Any pointers please for the reason ISRO moved to gas-generator cycle engine

You can ask this question directly to ISRO at
https://www.facebook.com/isroofficial

arun · Post by **arun** » 05 Jan 2014 18:23

prasannasimha wrote:Gas generator cycle technology is cheaper though less efficient.

From an efficiency standpoint I thought it was the reverse going by the better thrust weight ratio of engines using the Gas Genarator Cycle vis a vis engines using the Staged Combustion Cycle.

See page 5 of this 2006 presentation titled “Challenges In Cryogenic Development Present & The Future” by then C25 Project Director N.K.Gupta:

Challenges In Cryogenic Development Present & The Future

member_28108 · Post by **member_28108** » 05 Jan 2014 18:29

vina wrote:
prasannasimha wrote:Gas generator cycle technology is cheaper though less efficient. The US used staged combustion type but they now also use gas generator ones which they got from Russia as the costs are considerably less.
You couldn't be more wrong and you have got it backwards. The issue is not cost,but engineering complexity and difficulty. The US considered the oxygen rich staged combustion cycle "impossible" and went for the fuel rich gas generator cycle which is less efficient because of pumping losses.

It is the Russians who perfected the oxygen rich staged combustion cycle for their NK-33 engine and it's derivative is the RD-180 which the Americans use as their main stage for nearly all their launch vehicles now (Atlas etc) which is imported from Russia.

Anyways, that is another topic which you can see for yourself online.

Today, we have a staged combustion variable thrust engine that has a high specific impulse and is as good as any of the best out there (when it is grown to full potential, can be the best ), in fact better than the Russian KVD-1 stage that it replaced, which when we are talking of rocket engines is a tremendous achievement indeed. So enjoy the moment.

Vina, actually I am not wrong (though I am subject to correction) - have a look at why the US developed the RS-68 engine even though they had the SSME. Theis is from the Wiki reference

http://en.wikipedia.org/wiki/RS-68

A leading goal of the RS-68 program was to produce a simple engine that would be cost-effective when used for a single launch. To achieve this, the RS-68 has 80% fewer parts than the multi-launch Space Shuttle Main Engine (SSME).[2] Simplicity came at the cost of lower thrust-efficiency versus the SSME: the RS-68's thrust-to-weight ratio is significantly lower and the RS-68's specific impulse is 10% lower.[citation needed] The benefit of the RS-68 is its reduced construction cost.[2] The SSME's higher costs were designed to be spread across multiple launches, while the larger, more powerful RS-68 was designed to be a more cost-effective engine for an expendable launch vehicle.[citation needed]

Singha · Post by **Singha** » 05 Jan 2014 18:33

wiki specs of CE7.5 and CE20 seem to indicate for similar weight, the CE20 (gas generator) offers greater thrust, which would be a must for the heavier 4T into GTO payloads of the MkIII. thats probably the reason.

also look up RD 180....a true beast...empty weight itself is 5.5tons...around 10X the CE7.5/CE20....uses staged combustion....so maybe there are secrets to scaling up staged combustion we dont know yet and gas generator offers a technically feasible path for now.

their latest puppy the RD191 for the next gen Angara launcher family again uses staged combustion cycle

so looks like one has to master both cycles with credible products to be considered a true Jedi. to have only one is to be a Sith.

Supratik · Post by **Supratik** » 05 Jan 2014 18:36

A milestone. Congrats.

KrishG · Post by **KrishG** » 05 Jan 2014 18:36

Brando wrote:The current CE7.5 is a staged combustion cycle engine. The CE20 that is to be part of the GSLV MK3 is supposed to be a gas-generator cycle engine. Does anybody know why they changed technologies especially when staged combustion cycle is more efficient ?

When ISRO started the development of LVM3 (MkIII) all the 3 operation cycles for the CE20 (to generate 20 tonnes of thrust) engine were studied.

ISRO chose to go with Gas Generator cycle because:
* The required outlet pressure for Hydrogen in the GG cycle is significantly less (less complex)
* The advantages that the other cycles offer (which they do like allowing a bit more payload) were not required for the requirements and role ISRO needed for this engine/stage.

Here's the comparison between different cycles for the 20 tonne engine that ISRO studied.

member_20317 · Post by **member_20317** » 05 Jan 2014 18:39

Congrats everybody. I had heard of cryo tech being chased by Indian establishments (imports route), for the first time in 92 when I was in 12th. Long long journey. But did that at last. Congrats everybody again and may god bless your every effort in these directions.

member_25400 · Post by **member_25400** » 05 Jan 2014 18:51

dhiraj wrote:^^^^^^^^^^^^^^^^
So if staged combustion is better than gas-generator cycle engine then why move to an inefficient tech for CE - 20 when
we have mastered staged combustion in CE 7.5 ?

Efficiency matters. But Thrust matters (CE20 vs CE7.5) and reliability and ease of development also matter hugely.
It's not a flat "better" but a question of trade-offs. Gas generator can have simplified plumbing and turbine design, and this can result in a less expensive and lighter engine, and less worries about feedback and control (in some cases, fewer concerns about vibration and corrosion).

Staged combustion can improve few % of thrust by using the turbine exhaust, and this has bonus benefits for first stage low in atmosphere , with higher back pressures (which don't apply for a upper stage).

eg for the shuttle main engines, NASA wanted to maximize efficiency and thrust and spread the cost across multiple launches of the engine. But for the RS68 that powers Delta IV, the goal was to minimize cost for an expendable/throw-away engine; with 80% fewer parts, lower thrust to weight ratio, and 10% less specific impulse, it was still successful by reducing construction cost. (Whereas, the space shuttle never did achieve the re-use, with lower number/frequency of launches and substantial inspection/refurbishment between launches.) So you see, the application trade-off matters substantially here.

I would bet that the added thrust, and simpler engine (development, production and control) may tend to make up for few % loss in specific impulse/efficiency that tend to go with gas generators based design.

But I don't know ISRO reasoning and decision in this specific case.

edit: KrishG posted with specifics and numbers from ISROs study while I was composing this post. It removes all speculation.

vasu raya · Post by **vasu raya** » 05 Jan 2014 18:57

Congragulations! ISRO's extensive testing helped their cause this time, ideally they should have setup the infra way earlier, maybe this becomes a case study to be used aganist the bean counting financial babus

member_22019 · Post by **member_22019** » 05 Jan 2014 19:17

Congratulation, Great Achievement. Please can someone request goi to hand over kaveri project to isro

sum · Post by **sum** » 05 Jan 2014 19:21

^^ Hands and legs were sweating watching the post-launch highlights video itself! Cant imagine the tension in the room at the time.

Amazing stuff, ISRO!

SSridhar · Post by **SSridhar** » 05 Jan 2014 19:28

The below is what I posted many years back here. Link

Folks, just a small note on the cryogenic engine.

The propellant feed system in a liquid rocket motor (which is what a cryogenic engine is ultimately), can be achieved by either by pressurized or a turbopump feed system or a combination of the two. In a pressurized system, the propellants (both fuel & oxidizer) are forced out of their tanks by employing a high pressure inert gas. In a turbopump system, the propellants are pumped out by means of pumps which are driven by turbines. Where large propellant flow is required, as in the CUS Engine, the turbopump mechanism is employed.

In a turbopump feed system, turbines run the pumps for pumping the LOX & LH2 into the thrust chamber. So, the engine requires pump(s), turbine and the gas. The gas is generated on-board through one of the following means:
1. In a precombustion chamber
2. In a separate gas generator
3. By circulating LH2 through the cooling jacket surrounding the combustion chamber which achieves the twin purpose of cooling the chamber and transferring the heat to LH2 to generate the gas
4. By bleeding hot gas from the combustion chamber
After flowing through the turbine, the gas can be exhausted through a separate nozzle or through the nozzle of the engine or injected back into the combustion chamber

One way of characterizing the turbopump engine cycle is either open or closed. In the 'open cycle', the exhaust of gas from the turbine exits either through a separate nozzle or the nozzle of the engine. It is a 'closed cycle' if the gas gets back into the combustion chamber. The closed cycle gives obviously a slightly improved performance.

Another way of characterizing the turbopump engine cycle is by the way the gas is generated and supplied to the turbines. In the technique employing a separate gas generator (Point 2 above), which is known as gas generator cycle, a small amount of LOX & LH2 is burnt to generate hot gas that drives the turbine. In the staged combustion cycle, a precombustor is employed (Point 1 above). The coolant (always LH2) flows through the cooling jacket of the thrust chamber and the entire coolant is fed into a precombustion chamber where a part of the oxidizer is also injected to burn and generate gas. This gas drives the turbine and the exhaust from the turbine is injected into the thrust chamber where it burns with the rest of the oxidizer. This gives the highest Isp. Since the entire exhaust from the turbine is injected into the combustion chamber, the staged combustion is a closed cycle engine.

sumishi · Post by **sumishi** » 05 Jan 2014 19:40

Late for the party ..... WOW ISRO! Congrats!

My "Ode" to our Skylark (GSLV):

Our Cryo history is too full of kinks,
Fuelled by Unkil and his arm-twisting links,

Today we gave the cry,
with a roar that inked the sky,

Now Unkil sure looks Jar-Jar-Binks.

Raja Bose · Post by **Raja Bose** » 05 Jan 2014 19:45

member_28359 · Post by **member_28359** » 05 Jan 2014 19:49

CONGRATULATIONS..................I remember when I was in the 7th standard the cryogenic sale from Russia did not happen...........read about it a lot in the newspaper at that time.....I remember asking my father about the meaning of cryogenics and he actually went and asked one of his colleagues who apparently was highly qualified,anyway he came to our house and explained cryogenics to me.....didn't understand much at that time except the fact that it had something to do with low temperatures......

Kakarat · Post by **Kakarat** » 05 Jan 2014 19:51

Launch Photos from ISRO website

vina · Post by **vina** » 05 Jan 2014 20:13

Singha wrote:wiki specs of CE7.5 and CE20 seem to indicate for similar weight, the CE20 (gas generator) offers greater thrust, which would be a must for the heavier 4T into GTO payloads of the MkIII. thats probably the reason.

also look up RD 180....a true beast...empty weight itself is 5.5tons...around 10X the CE7.5/CE20....uses staged combustion....so maybe there are secrets to scaling up staged combustion we dont know yet and gas generator offers a technically feasible path for now.

their latest puppy the RD191 for the next gen Angara launcher family again uses staged combustion cycle

so looks like one has to master both cycles with credible products to be considered a true Jedi. to have only one is to be a Sith.

The trouble with the GSLV MK1 & MKII was that there is a design "flaw" (if you can call it). The core stage burns up before the zero stage strapped on boosters, so the boosters lug the empty weight of the core stage for a good couple of seconds. That carrying dead weight is extremely wasteful and you need every bit of efficiency you can extract from the upper stages to somewhat makeup for that fault.

That "fault" might have come about because they wanted to make maximum reuse of the PSLV hardware to jump to a GSLV and not a full clean sheet design. Ideally, the moment a part has served it's function, you discard it in rockets. That is the fundamental way in which rockets achieve efficiency (you don't carry a single bit of flab around).

With MKIII being a clean sheet design, my guess is that it is not critical to go for bust in the top stage and we could well tolerate a few percentage drop in Isp (specific impulse) for the MKIII and we went with the advantages of easier design with gas generator in MKIII upper stage. MKIII to is sort of stop gap in the core. You ideally want a very high Isp staged combustion Hydrocarbon/LOX stage instead of the Vikas derived twin engine core and that is what the ISRO semi cryo program aims to achieve.

krisna · Post by **krisna** » 05 Jan 2014 20:17

wanted to be awake for the GSLV launch- almost had the blind confidence that it will be successful.
But ended up sleeping- my little one woke me up early am- checked the smart phone- teetar full abuzz with GSLV success.
ended up smooothering my naughty one with kissess to his amazement which he liked.
for once never minded being woken up at that time despite being sunday with a splittting headache.

shq replied - oh is it so.

Guess ISRO thinks the same of its naughty kid- the coolest hot engine.

Cosmo_R · Post by **Cosmo_R** » 05 Jan 2014 20:23

Sorry but cannot resist:

"Why does India make fools of themselves messing in space technology? Stick 2 bollywood my advice."

Salman Taseer 2010

O! Quadrified one, you deserve an answer: we have our eyes on the stars. You and your ilk have theirs on mud.

Victor · Post by **Victor** » 05 Jan 2014 20:28

Wow! Major milestone crossed. Congrats to India and ISRO. Going by PSLV example, this will become routine in no time. All doors are open and the lucrative launch bijness beckons!

Day of pride for all Indians.

On another note, why do we need a variable thrust engine with restart capability for a launcher if that is what we indeed have?

Raja Bose · Post by **Raja Bose** » 05 Jan 2014 20:35

Guys stop polluting this thread with discussion of drain inspection by white pakis - they can go cry themselves silly with the big FU they just got for all we care. I am deleting such posts.

Gurneesh · Post by **Gurneesh** » 05 Jan 2014 20:40

Awe-f***ing-some...

. Good job ISRO and wish you many successes in the future. Could not have woken up to a better news..

member_28108 · Post by **member_28108** » 05 Jan 2014 20:49

Variable thrust -required to dial in the thrust required for a particular mission(weight of payload etc)

SriKumar · Post by **SriKumar** » 05 Jan 2014 20:58

In the DD video, seems like both the commentators are technical people: Alok Shrivastav (Project Director, GISAT) and D. Radhakrishnan (Director-Launch Services). Quite a departure from the regular DD commentators and much better technical detail, but a lot of cross-talking. I do wish there was also a parallel broadcast with the only comments heard from the ISRO engineers working the launch, just the audio perhaps.....one could not hear the call-outs in this one, for example, Parfarmance Naarml.

(from range director: Paneerselvan). Cryo-shutoff at about 55:15.

The very public nature of the launch data display, in real time, speaks to the confidence of the ISRO.
Towards the very end, K.Radhakrishnan thanks MMS for his full support after the 2010 failure. Good thing no netas giving bhashan today.

kvraghavaiah · Post by **kvraghavaiah** » 05 Jan 2014 21:11

SiddharthS wrote:Congratulation, Great Achievement. Please can someone request goi to hand over kaveri project to isro

Delete this post. This statement is very bad.

arun · Post by **arun** » 05 Jan 2014 21:14

Cosmo_R wrote:Sorry but cannot resist:

"Why does India make fools of themselves messing in space technology? Stick 2 bollywood my advice."

Salman Taseer 2010

O! Quadrified one, you deserve an answer: we have our eyes on the stars. You and your ilk have theirs on mud.

The successful launch of the GSLV D5 was impeccably timed missing as it did Salman Taseer's death anniversary by a day.

Meanwhile moot to point out that while India has seen a satisfying riposte to Salman Taseer's jibe, Salman Taseer enjoys nothing of the sort with regard to his being Haji Bull Cutletted as his murderer Mumtaz Qadri continues to be very much alive.

pgbhat · Post by **pgbhat** » 05 Jan 2014 21:16

AoA!!! Congrats to ISRO. Photos are awesome!

Hari Seldon · Post by **Hari Seldon** » 05 Jan 2014 21:21

Many congratulations to ISRO and our scientist community... You're the best!

putnanja · Post by **putnanja** » 05 Jan 2014 21:31

Awesome! Looking forward to more such successfull launches, so that an year down the line, we won't have separate thread for GSLVs, but just couple of pages in the space thread

Onwards to GSLV-MKIII !!

Had a question on different type of engines for Mk-II and Mk-III. Why didn't they go for the gas generator engine in Mk-II itself? Wouldn't it have made more sense both in testing/scaling up and cost if they use same type of engine for both Mk-II and Mk-III?

Prasad · Post by **Prasad** » 05 Jan 2014 21:35

Har har mahadev! What a beautiful launch! Now onto heavier launch weights. And more consistent launches.

Now strap on some cameras onto the gslv for the next launch and give us some hd video Of stage separations and lift off from the pad. Prof yashpals comments were heartfelt at the end I thought. Social messages help, especially when we have Idiots who ask everytime we launch asking why fund thsse guys play with rockets.

Truly inspiring ISRO