Indian Space Program: News & Discussion - Sept 2016

prasannasimha · Post by **prasannasimha** » 04 Jun 2017 14:23

Singha wrote:I am curious why the payload fairing separation is at 3:45 rather than just before 16:05 when the C25 stage will shut down. it might save a ton or two i suppose ?

Payload fairing is always jettisoned after crossing the dense atmosphere once aerodynamic advantage is ovee and shock waves settles. After this lugging that weight is meaningless if the vehicle is accelerating and not in stable orbit.

Neela · Post by **Neela** » 04 Jun 2017 14:35

vina wrote: The GSLV Mk 2 in comparison (figures again from Wiki) can launch 2.5 tons to GTO and costs Rs 220 crores ($ 36 million) per launch. That works out to $14,400/kg. I doubt whether the GLSV Mk 3 cost/kg will be significantly different.
Yes. FINALLY SOMEONE who actually posts numbers instead of "I think" and "I feel" .
So, why is Space X launches significantly cheaper than the GSLV MK2 , more so when wages and other costs are far higher in the US ? And how is it that in India, despite whipping the ISRO folks hard and feeding them "poo", the GSLV Mk2 ends up being more expensive than the Falcon ?
Answers .
1. Open, any standard book /google and look at "Growth Models" (Solow Growth Model is easy to understand), and you can find out that that in the long run, PRODUCTIVITY alone creates growth. Productivity --> efficiency . So more efficient you are , you create surpluses that can be shared. So that is why, despite whipping the folks in ISRO hard and feeding them "poo" , you will end up with a more expensive machine than a Space X which feeds it it's folks gruel and kicks them hard in the ass ..
2. Economies of scale kick in. Just like in a plane, ship , truck etc, the cost per ton kicks in with higher payloads due to economies of scale and the per unit cost comes down. That is why it is cheaper to launch 2 , 5 ton satellites on 1 launcher of 10 tons, instead of 5 ton on a single rocket. (same reason why the cost per seat mile in a A380 is far cheaper than in an A320. It is cheaper to fly one A380 to transport 450 passengers, than fly 4 A320s to fly the same number of people)
In the list of mass fractions posted above, what is missing is Atlas V. With the RD-180 and Centuar upper stage, it will have the highest mass fraction among everything else out there (along with Space X and LM5 ) for like to like config. Reasons are.. 1) Ariane V mass fraction and GSLV MKII & III mass fractions drop because of the use of solids.
Cheaper solids vs liquids engines holds somewhat (does it really ?) only for single use rockets. With reuse like what Space X and others are thinking of , it will tilt tremendously towards liquids, which together with their higher efficiencies will simply crush solids in long run.
Reading on the wall. Solids for space launch business is going the way of the Dodo. Solids are perfect for Missiles. Not so for space launch, particularly so if you factor in reuse, like the industry is going for.
Also, with solids, for a large launch vehicle, you absolutely NEED the vertical assembly and cost infra associated with and transporting a vertically assembled vehicle. Not so for a liquid. The empty rocket is practically weightless ,it is assembled horizontally in an el Chepo building, rolled out horizontally and then jacked up, the fuel and oxidant is pumped in and fired (Soyuz and Space X) . You need to factor those costs in as well.

Great post as usual Vina ( After reading ldev's post, I was thinking if you'd follow up with a post with the words "higher efficiences" in it and here it is)
Your message has been consistent all along. Right from lugging the solid boosters for extra ~40s to handling/mass fraction/choice of liquids - all focusing on the math and efficiency.

deejay · Post by **deejay** » 04 Jun 2017 16:29

All the best team ISRO.

nirav · Post by **nirav** » 04 Jun 2017 17:28

T-24 hours.

Singha · Post by **Singha** » 04 Jun 2017 17:39

Falcon is going for aesa array of tens of small liquid engines. So did abortive soviet lunar rocket pgm.

Is ant grid better or a giant 1 or 2 beast engines?

Singha · Post by **Singha** » 04 Jun 2017 17:46

This was more like it. The right stuff
https://en.m.wikipedia.org/wiki/Energia

prasannasimha · Post by **prasannasimha** » 04 Jun 2017 18:41

Propellant filling operations of L110 (Second Stage) of GSLV Mk III D1 are under progress. Countdown is progressing normally.

SSSalvi · Post by **SSSalvi** » 04 Jun 2017 20:40

prasannasimha wrote:^^^SSSalvi o don't think that it is over significant land mass . If the flight footprint is taken it is all over the ocean just like previous GTO launches. The 3D rendering is just giving that impression.

Tried to plot the 1st point ( 41 kms altitude ) over the sea coast and navigating globe to a similar view as shown by ISRO. ( We can't get the exact position because the lat-longs are not known )
But the point still does not appear to move to the location rendered by ISRO.
We have to wait till the real-time launch video starts.
As it is the release of huge S2000 motors at an altitude of 60 kms is scary .. they have to burn and evaporate before reaching ground.

Singha · Post by **Singha** » 04 Jun 2017 20:47

The notam map is a line traversing toward malacca strait...

Ashokk · Post by **Ashokk** » 04 Jun 2017 21:06

SSSalvi wrote:Notice that the path is totally passing over the populated landmass indicating the confidence that ISRO has in its maiden launch of GSLV MkIII,

Also note that the Core motor of 1st stage is ignited AFTER the initial liftoff by strap-ons upto an altitude of 41 kms !

I think the map is shown in 3D - the grid is in the vertical plane wrt to the land mass. It will be launched eastwards like we usually do, ties in with the NOTAM as well.

prasannasimha · Post by **prasannasimha** » 04 Jun 2017 21:18

The ground trace is clearly shownin the picture. Look at the lowest line of the "Plane" of the flight path to the corund trace. Lower down you can see the ground trace. it is not a 2D rendering but a 3D rendering in a plane.

prasannasimha · Post by **prasannasimha** » 04 Jun 2017 21:19

Follow the yellow line saying LA 107 and then extended to a dotted white line along the arrow

Varoon Shekhar · Post by **Varoon Shekhar** » 04 Jun 2017 22:27

Can't help but notice a general sourness by the 'experts' or analysts( particularly from the Wire) on this upcoming launch. The only reservation people should really have, is some goosebumps about the actual success of the mission. It is going to be a very suspenseful, complex and difficult one. Other than that, why all this negativism and talking down of the vehicle. Even with someone like R.Ramachandran of Frontline, it's more the 'downside' than the upside. Listing all the missteps ISRO has reputedly taken over the years. He should be really excited, at the least cautiously optimistic, about the launch. As should everyone.

prasannasimha · Post by **prasannasimha** » 04 Jun 2017 22:34

SSSalvi · Post by **SSSalvi** » 05 Jun 2017 00:52

The ISRO graphic IS misleading.. you can't expect a man in the street to concentrate ( and interpret the vertical plane ) to understand the path.

Ok, It was my bad. Let's follow the launch.

vina · Post by **vina** » 05 Jun 2017 04:02

Singha wrote:Falcon is going for aesa array of tens of small liquid engines. So did abortive soviet lunar rocket pgm.

Is ant grid better or a giant 1 or 2 beast engines?

Falcon etc ..Make 1 engine (i.e. for the 2nd stage) and use the same engine in a multiple cluster with a different nozzle in the lower stage. Other examples .. Ariane 4 (1 Viking in the 2nd stage, 4 vikings clustered in the core + solid boosters). LM 3 /4 (1 Viking class in the 2nd stage, 4 clustered in the core + 4 more as boosters), and of course our own GSLV Mk2 (1 Viking in 2nd stage + 4 (unfortunately) as boosters).

So really, what Falcon is doing is not something radically different. What it has done is that in the name of re-use, it has clustered 9 of those 2nd stage engines into the 1st stage (with different nozzle of course). The Chinese LM3 for eg. uses 8 of the 2nd stage engines in the core. The difference is that since Space X is designed for re-use , it has clustered them all into one block and not part as boosters (like the Soyuz,LM etc) so that they can recover ALL engines at one go (boosters are more efficient, it is like staging, drop spent mass that is of no use any more).

Falcon is designed to be cost efficient via reuse and simplification and they made compromises in technical efficiency for that (for e.g., they didn't go for a LH2/LOX upper stage.. don't believe Elon Musk's B.S about Mars and using Methane there or whatever, that is just so much gas..).

Soviets on the other hand, their engines have multiple nozzles (RD -170/RD180 etc), but the turbo machinery is shared. i.e. there is only one set of pumps and pre burner etc. The reason is combustion instability the soviets experienced earlier on. The max they could get the combustion going stably was a chamber and nozzle of approx. 2MN size. So their solution - have same turbo machinery , but split the thrust into multiple thrust chambers and nozzles of 2MN each. A pretty neat solution . They didn't try to do what was "unobtanium" for them, rather did a nice work around with what was working for them.

The largest engine with a SINGLE chamber and NOZZLE to this day remains the F-1 engines from the Saturn V. They were engineering marvels back in those days an remain so to this day. They are in the class of the RD-170 (approx 8MN), the RD-170 has 4 chambers and nozzle, while the F-1 is a single nozzle & chamber. The RD-170 has of course a higher IsP (more efficient) because it is a staged combustion cycle engine, with the F-1 is gas generator cycle , because the staged combustion is thermodynamically more efficient (less pumping loses because all the flow goes , including from the pre burner through the nozzle and not partially dumped overboard like in the gas generator cycle).

Notice that for the Saturn V, they clustered 5 of the giant F-1s in the core in the 1st stage. So you will eventually need to cluster for very large rockets. It is not a question of "or" , but "when" .

Gagan · Post by **Gagan** » 05 Jun 2017 04:36

On the Mk 2, if they could bring the 4 liquid strapons together as a cluster in the core, and use solid strapons, they might avoid the 40 second weight dragging that Vina keeps talking about
It might have payload advantages

disha · Post by **disha** » 05 Jun 2017 04:58

^^ How much?

On this very thread few pages back., it was determined that increasing the burn-time of solid stage 1st stage of GSLV mk1/2 will increase the payload at most by few low hundred kilos. Not a significant gain.

There is a very very very valid reason on why the reverse (solid core inside) and liquid strap-ons outside was done. Take a careful look at the launch sequence. Only when the thrust from the liquid strap-ons is optimal., the solid stage is ignited.

Two failures (including the first partial failure) were due to issues with liquid strap ons. Solid stage once ignited cannot be shutdown., so igniting after all the liquid strap on boosters provide the nominal thrust made sense.

ISRO had the following proven stages:

1. Solid stage from PSLV - S138/S139 - Burn time @100 seconds.,
2. Liquid engines (800 kN) - Burn time @160 seconds.,

For GSLV Mk 1/Mk 2., they knew that they need a cryo to kick the satellite into orbit. How ISRO settled onto Russian KVD is known., so no need to rehash here.

Remember, ISRO operates on shoe-string budget and the years of 1990-2001 were very brutal for the Indian economy. To ask for a separate budget to develop an altogether new stages just to gain few hundred kilos was uncalled for. By reusing stages/engines between GSLV/PSLV., ISRO did achieve an economy of scale.

On the cryo-engines from Russia., ISRO might not even have known about the RD-180 engines scooped up by the Americans. Remember., the RD-180 were ordered to be destroyed but were squirreled away and revealed to NASA engineers right after Soviet union breakup and chaos prevailed. And anyway., ISRO chief would not have gone over there asking "Kitne RD-180 engines hain"! So to say that RD-180 tech might have helped GSLV-Mk 1/2 which was an evolutionary design is a speculation which is now moot given that ISRO has its own staged-combustion CUS and now its own GG C-25.

%%%%

Look at the timeline., PSLV first flew in 1993., and by 2001 (eight years later) ISRO acquired GTO launch capability. And full twenty years later had acquired fully indigenous capability to GTO.

In that sense what was the goal of GSLV-Mk 1/2? Realize cryo-tech and acquire GTO launch capabilities. It achieved both.

Doing a rona-dhona of "GSLV lugs 1st stage for 40sec" is just that., a pure non-sensical rona-dhona. It is akin to say "LCA lugs dead-weight with an underperforming GE 404 engine".

So what does the future entail? Take a look at the diameters of the S-200 and the payload adapter of GSLV-Mk 2. In a nutshell, ISRO can do the following:

1. Replace the S-138/139 with S-200.
2. Increase the volume of the second stage liquid engine tanks to 3.2 m., I think it is 2.4 m now. Increase the burn-time
3. Increase the propellant loading of CUS to 15 tons (it was indeed tried out in GSLV Mk1c I think but failed due to snapped connectors).
4. Increase the thrust of CUS from current nominal 7.5 kN to 9.3 kN.

What will that do? Optimize the "dead lugging" problem., and further adds 1-tonne to the GTO capability for GSLV-Mk II. It will be a behemoth that will take 3.5 tonnes to GTO., and will be a versatile rocket for deep space missions (lunar/mars/venus/lagrange-points) etc.

vina · Post by **vina** » 05 Jun 2017 05:00

Gagan wrote:On the Mk 2, if they could bring the 4 liquid strapons together as a cluster in the core, and use solid strapons, they might avoid the 40 second weight dragging that Vina keeps talking about
It might have payload advantages

The train has left the station for the Mk2 . It is (along with the PSLV) is ageing and really obsolete . Both the Mk2 and the PSLV will be replaced with twos stage to orbit vehicles with a lower stage of kerosene/Lox and upper stage of LH2/LOX. In fact, even the GSLV Mk3 is obsolete as it exists. The L110 stage will soon be replaced by a semi cryo stage to realise the full potential inherent in the airframe.

The only chance for the clustering business was when ISRO built the core for the Mk3 . Instead of a L110 (by clustering 2 Vikas) they built for the Mk3, if they had built an L220 of the Ariane 4 (which clustered 4 Vikas), they could have used it both in the Mk2 and not developed the 4 Ton class GSLV Mk3 as it exists now. ISRO chose to develop a brand new vehicle instead of "fixing" the GSLV Mk2 to realise the full potential (around 5 Ton to GTO) that was inherent in that class of vehicle with that technology level (Ariane 4 and LM3).

Refer to the "Make your Own rocket" thread that probably has been archived. All these were discussed there, including with calculations and multiple options. The "gain" is not a "few kilograms", but a few HUNDRED kilograms. The difference is 2.0 to 2.5 Tons to GTO extra, which is what the Ariane 4 and LM3 (which are exactly similar vehicles , achieve - around 5 tons vs 2.5 tons GSLV Mk2).

disha · Post by **disha** » 05 Jun 2017 05:40

^^ rolling eyes only. GSLV Mk-II launched 2.2 tonnes Indian-Subcontinent satellite. So to your 2.5 tonnes to GTO - that is a mere 300 kg. extra.

In 90s., ISRO simply did not have the budget to design an entirely new series of stages to achieve a mere 300 kg. extra GTO launch weight.

---

GSLV - Mk II is "obsolete" is the meme which was published in "The cHindu" paper. And the meme is repeated here., and again will be picked up and repeated somewhere else.

Initially it was amusing., but now it is tiring to just think - how a 7.5/9.3 kN staged combustion cryo engine/stage is considered a "waste"?

The major goal for any serious space agency is to have a *RELIABLE* launch capability. Once GSLV-Mk III launch is operationalized (after 3 successive launches)., I think, GSLV-Mk II will be tinkered around., PSLV will be retired and GSLV-MkII may end up taking PSLV's role. In the meantime, it will be a 2-decades from now before a significant TSTO and or RLV capability is realized.

In space launch., no reliable launch capacity is considered obsolete. Even SLV's - which is a 1979 tech.

Vivek K · Post by **Vivek K** » 05 Jun 2017 05:55

MkII is still a very useful vehicle and ISRO will tweak its payload capacity to exploit its potential to the fullest. A reliable system always trumps another on the drawing board. Thank God that ISRO is following a realistic path. Let us all focus on MKIII for now.

nirav · Post by **nirav** » 05 Jun 2017 06:22

disha wrote:
In space launch., no reliable launch capacity is considered obsolete. Even SLV's - which is a 1979 tech.

The "obsolete" technology has precisely injected it's payload in Lunar orbit and Martian orbit.
Good enough for us SDREs.

Btw i was wrong in observing that ISRO bashing happens every few months.
It happens when there's a significant launch due.

I'm certain though, raakit ki garajna will out thunder the noise on this thread come 17:28 hours today !

vina · Post by **vina** » 05 Jun 2017 06:29

disha wrote:^^ rolling eyes only. GSLV Mk-II launched 2.2 tonnes Indian-Subcontinent satellite. So to your 2.5 tonnes to GTO - that is a mere 300 kg. extra.

Much as I hope to simply ignore your trolling , it sometimes become irresistible , in the lack of basic reading comprehension and elementary arithmetic and that leads me to wonder if you actually think at ALL before you type or you just vomit something up verbally and are done with it.

Case in point above. The difference between 5 tons and 2.5 tons is 2.5 TONS extra . That is NOT 300kg. Arithmetic man. My son in 1st grade will answer 5000 - 2500 = 2500 correctly.

Another nugget of your's which I ignored..

There is a very very very valid reason on why the reverse (solid core inside) and liquid strap-ons outside was done. Take a careful look at the launch sequence. Only when the thrust from the liquid strap-ons is optimal., the solid stage is ignited

Ah. I see, THAT is the reason why the core is a solid and liquids are outside in the GSLV Mk2.

Now we learn that , if the liquids are arranged outside , they can be ignited first and then the solids are ignited later. However, if you cluster the liquids are clustered in the core , and solids arranged outside , the liquid core cannot be ignited first and the solids ignited later. Why so ? I can't find any logical reason why it should be so.

I will suspend the fact that every vehicle from Space Shuttle to Ariane to Titan do exactly that , ignite the liquid core first and then then the solids are ignited later.

Listen. Do post by all means. I have no problems and that is exactly what this thread is for. But at least post stuff that can stand up to basic scrutiny with known scientific facts. That will add value to everyone here.

Gagan · Post by **Gagan** » 05 Jun 2017 07:04

They tried to correct the errors of the MK2 in the MK3 by having a 2 engine liquid cluster in the core and the solid strap ons.
But are they being too conservative here? Unfamiliarity with clustering, or familiarity with a 2 engine cluster as on the Prithvi?

I wonder if the upcoming developments have a 4 engine semi cryo cluster

hnair · Post by **hnair** » 05 Jun 2017 07:18

Enough, vina and disha - a caution at this point

Let us wish the 1000s who made MK3 possible, great success.

Gyan · Post by **Gyan** » 05 Jun 2017 09:55

Commercial GSO Satellites are peaking out at weight of around 6-7 tons, hence higher payload may not really be required.

Pratyush · Post by **Pratyush** » 05 Jun 2017 11:37

After a long run of successful and boring PSLV launches. I am very excited about this launch and am eagerly looking forward to it.

suryag · Post by **suryag** » 05 Jun 2017 11:38

we might need some anti jinxing given the level of excitement and anticipation

Ashokk · Post by **Ashokk** » 05 Jun 2017 12:59

Propellant filling operations of L110 (Second Stage) of GSLV Mk III D1 are completed.

sooraj · Post by **sooraj** » 05 Jun 2017 16:40

http://cdn.24fd.com/events/isro/050617/ ... index.html

negi · Post by **negi** » 05 Jun 2017 17:27

Disha and Co what are your views on CE 7.5 and the CE 20 ? Have we ditched the staged combustion cycle or we have plans for bigger engines to replace the L110 which may employ the staged combustion .

Murugan · Post by **Murugan** » 05 Jun 2017 17:30

It was quick

Gagan · Post by **Gagan** » 05 Jun 2017 17:55

The GSAT-19, will send out spot transmission in a circular area, focusing on its ground receiving stations, and not all over the general area.
They need the antennaes to be stabilized, and focused to those specific areas, prevents data being seen outside the designated areas.

This GSAT-19, is a test bed for a host of technologies - must now forget the new ground being broken on the satellite front.
Indigenous star sensor, a host of things !!!

akashganga · Post by **akashganga** » 05 Jun 2017 18:32

Congratulations ISRO. It is a great day for India. Time to celebrate.

kurup · Post by **kurup** » 05 Jun 2017 18:43

Below image shows the path of MK3 flight .... it will clear the doubts about MK3 flight over populated area ..... the flight is towards the andamans .... by the time HS separates over BoB , the rocket would have left the atmosphere .... so it doesnot really matter much about the flight path .

kurup · Post by **kurup** » 05 Jun 2017 18:46

negi wrote:Disha and Co what are your views on CE 7.5 and the CE 20 ? Have we ditched the staged combustion cycle or we have plans for bigger engines to replace the L110 which may employ the staged combustion .

The L110 stage will be replaced by SC200 (200 tons Semi-Cryogenic) stage powered by SCE200 (200 tonne thrust Semi-Cryogenic Engine) using stage combustion cycle .

abhijitm · Post by **abhijitm** » 05 Jun 2017 18:49

GSLV MK3 is Bahubali

Kakarat · Post by **Kakarat** » 05 Jun 2017 22:08

kurup wrote:
negi wrote:Disha and Co what are your views on CE 7.5 and the CE 20 ? Have we ditched the staged combustion cycle or we have plans for bigger engines to replace the L110 which may employ the staged combustion .
The L110 stage will be replaced by SC200 (200 tons Semi-Cryogenic) stage powered by SCE200 (200 tonne thrust Semi-Cryogenic Engine) using stage combustion cycle .

I read somewhere that CE-20 is Gas Generator because its less complicated to develop than stage combustion cycle
There is also an CE-60 under development using stage combustion cycle for TSTO RLV application

Kakarat · Post by **Kakarat** » 05 Jun 2017 22:11

X-post from GSLV-Mk III launch program/post-launch analysis

Kakarat wrote:GSLV MkIII D1 in flight seen from Chennai

S200 Booster separation from GSLV MkIII D1 seen from Chennai

sanjaykumar · Post by **sanjaykumar** » 05 Jun 2017 22:48

One question-how does ISRO get the rocket to do those jumping maneuvers from top to bottom and side to side for the DD cameraman?