From the same article you quotedindranilroy wrote:Read here.prasannasimha wrote:There will not always have a 0 angle of attack- for eg when there is a pitch or yaw.
Enough please!nirav wrote: This is exactly the reason why id said that such exercises are nothing but flights of fancy. And that theres wayyy too much science that goes into a space launch vehicle. You are only kidding yourself and those who think its a "scientific discussion" that spreadsheet rocketry can solve for and "fix" a space launch vehicle by jugaadu mix and match.
All pitching of heavy rockets inside the atmosphere is open loop gravity assisted turn at zero AoA. The pitch over at non-zero AoA that you are speaking of happens outside the atmosphere.prasannasimha wrote:From the same article you quotedindranilroy wrote:
Read here.
After the pitchover, the rocket's angle of attack is adjusted to zero for the remainder of its climb to orbit.
During the ptich maneuver the angle of attack will not be zero
Mega launchers for ISRO soon
http://www.thehindu.com/news/national/m ... 155342.ece
Heavy lifting: With advanced semi-cryogenic engines, ISRO's ability to carry massive satellites will be tripled by 2020. File photo shows rocket lifting off from Sriharikota in 2014. —
Apart from powering rockets to lift heavier satellites, it will also lower the cost per kilo.
An advanced Indian mega space launcher that can deliver ten-tonne and heavier communication satellites to space and using a semi-cryogenic engine is likely to to power ISRO’s launchers by around 2018.
That is the space agency’s next big space vehicle, having just achieved the GSLV for lifting 2,000-kg payloads. The agency is gearing up for first test flight of the GSLV Mark-III vehicle in December with a 4,000-kg payload.
Currently, the government has approved the development of the semi-cryogenic stage alone.
When fitted suitably into a launch vehicle, it will see India putting satellites of the class of 6,000 to 10,000 kilos — or with some variations, lift even 15,000-kg payloads — to geostationary transfer orbits at 36,000 km. The engine is expected to triple or quadruple ISRO's transportation ability.
Massive payloads
Pre-project work on what is called the SCE-200 began about four years back. "We plan to have an [semi-cryogenic] engine and stage capable of flight by the end of 2018 and try it on the GSLV-MkIII.
This would readily boost Mk-III's maximum lifting capability from 4,000 kg to 6,000 kg,” Dr K. Sivan, Director of Vikram Sarabhai Space Centre at Thiruvanthapuram, the lead centre for launch vehicle development, said.
Two years thereafter, around 2020, this will be enhanced to 15,000 kg by putting strap-ons in clusters — the stage where major European and U.S. launch providers already are.
The engine will use space-grade kerosene as fuel and liquid oxygen as oxidiser. The development is going on at the Liquid Propulsion Systems Centre and the ISRO Propulsion Complex at Mahendragiri in Tamil Nadu.
“The semi-cryogenic engine is getting fabricated. Testing of its pump and components has been going on. An engine testing facility is also getting set up at Mahendragiri,” Dr. Sivan said.
Apart from powering rockets to lift heavier satellites, it will also effectively lower the cost per kilogram to reach orbits, which is the goal of all space-faring nations, he said.
Liquid fuel
The high-power local capability is needed as Indian communication satellites move towards 5,000-plus kg and more from 2017. By then, ISRO plans to build and launch its heaviest 5,700-kg GSAT-11 spacecraft, although on a European Ariane rocket for a big fee. Its present rockets can lift only up to 2,000 kg to this orbit.
Dr. Sivan said, “The GSLV-MkIII that we plan to test in December has a core liquid fuel stage. When the semi-cryogenic engine gets ready, our plan is to replace the liquid stage with the SCE. We straightaway get six-tonne payload capability, two tonnes over what Mark III can give.”
Subsequently the plan is to have a modular vehicle (earlier called the unifield launch vehicle) which allows variations suited to different payloads; this being done with the PSLV with its three versions.
For example, Dr. Sivan said: “We can have a bigger semicryogenic stage with clustered engines, similar to what SpawceX did using nine Merlin engines. We can then get a payload of 15 tonnes in the GTO.”
In the years to come, India's space assets will play a much bigger role if and when hostilities break out on our borders, says Pallava Bagla.
The precision 'surgical strikes' that Indian soldiers carried out on terrorist camps across the Line of Control were ably assisted and facilitated by at least half a dozen satellites.
India is fast developing a huge capability called 'C4ISR' or 'command, control, communications, computers, intelligence, surveillance, and reconnaissance'.
The country has already put in place an Aerospace Command and experts who understand the nature of the 'surgical strikes' acknowledge that this new tri-services body played a key role in planning and execution of the midnight attacks.
The Indian Space Research Organisation evidently does not fight wars and is purely a civilian agency, but the capabilities it imparts to the nation are among the very best in world.
From watching over the terrorist infrastructure in Pakistan to providing two-way communication in desolate places to giving out accurate navigation signals, ISRO has built a formidable infrastructure that helps India protect its borders in day or night.
Not many Indians know of these deep capabilities that lie hidden within the portals of the space agency. But silently and steadily, the 17,000 strong work force of the ISRO contributes to keeping 1.2 billion Indians secure.
ISRO provides the necessary platforms, and then it is the user agencies that utilise its downstream products which means ISRO does not directly participate in the conflict.
K Kasturirangan, former chairman of ISRO, says "The space agency has a formidable suit of technologies and all are suitably deployed with each user agency utilising the assets to their best advantage."
So a high resolution imaging satellite can help in urban planning while also monitoring terrorist camps across the border.
Kasturirangan says a satellite image does not distinguish between friend and foe; that interpretation rests with the users.
Nobody doubts that ISRO's eyes and ears facilitated 'surgical strike' in Pakistan-occupied Kashmir at the staging points for terrorists.
In the years to come, India's space assets will play a much bigger role if and when hostilities break out on our borders.
Kiran Kumar, chairman of ISRO, says, "The Indian space agency will not be found lacking in helping secure India's national interests now and in future."
Today, India has 33 satellites in orbit around the earth and one in the Martian orbit. These include 12 communications satellites; 7 navigation satellites; 10 earth observation satellites and 4 weather monitoring satellites. This is one of the largest constellation of satellites in the Asia-Pacific region. Each is tailor-made for a specific purpose and each when needed helps protect national interests.
India has some of the sharpest eyes in the sky and to prepare for the 'surgical strikes' India's best bird in the sky, the Cartosat 2-series satellite launched as recently as June 22 played a key role.
From its 526-km perch, Cartosat 2 can peer at every object in Pakistan and can easily count the number of cars parked in
the grand mansion of Pakistani Prime Minister Nawaz Sharif.
With its almost 0.65-m resolution, as it rotates the earth every 90 minutes, this formidable spy in the sky can count every tank, truck and fighter aircraft parked anywhere in Pakistan or for that matter anywhere India desires.
Speaking about the capabilities of this ultra-sharp satellite, Kumar said: "The Cartosat 2 series has a unique capability of capturing a 1-minute video, which despite its enormous speed of 37 km a second, is able to focus at a single point for a minute."
In addition, there were three other earth imaging satellites Cartosat-1, Cartosat-2 and Resourcesat-2 that provide top class imagery during day time. Going further, ISRO seeks to develop satellites that have a resolution of 25 cm in the very near future.
In contrast, Pakistan has no such capability as its space programme has hardly lifted off.
Former ISRO chairman G Madhavan Nair says even China does not have such high resolution satellites, the best China has is about 5-m resolution.
Nair says "India invested heavily in space imaging technology and is now reaping the benefits."
India also flies some satellites that have day and night viewing capabilities called 'synthetic aperture radar satellites'. There are two in orbit, the RISAT-1 and RISAT-2.
Nothing can hide from these mean birds as they can see through cloud cover and are not blinded at night. Especially RISAT-2, which is among the best in its class and its revisit time is relatively short.
Assessing damage on the camps that harboured the terrorists would be relatively easy using the radar satellites. It is not that these satellites do not help civilian activities, radar satellites help monitor floods and have even been deployed to search for crashed planes and helicopters.
India has put in place a regional satellite navigation system called NAVIC as recently as April 28 -- the last of the seven satellites was launched -- and Prime Minister Narendra Modi spoke on its huge benefits.
This system gives better than 20-m accuracy for navigation signals akin to the American Global Positioning System in an envelope which extends about 1,500 km from the border on all sides.
The signals are being beamed down 24x7 all the year around. Only America and Russia have similar capability over the South Asian region, China is still putting in place its satellite navigation system.
The restricted signal which is available to the Indian armed forces is supposed to be even more accurate than the American GPS in the Indian region. Experts say it is unlikely that the Indian special forces used the hand-held devices from NAVIC to guide them to the terrorist camps as the devices are still being fine-tuned.
In the event of an all-out war, signals from NAVIC will undoubtedly help India target its missiles to unleash unprecedented punishment on the enemy. Since the satellite navigation system is in India's control there can never be any fear of someone switching the constellation off.
There is another 2,000 kg-plus bird that points towards the Indian region all day and night, and provides unprecedented capability to India's armed forces -- the GSAT-6. This unique satellite has multi-media capability as it can stream video in both directions. It has the largest antennae which is 6 m in diameter. This is one unique satellite which will play a crucial role in the network centric warfare of the 21st century.
Using a hand-held device, individual soldiers can connect and will be able to transmit live pictures of what they can see from their helmet mounted cameras even as they engage in combat. Launched last year the users are still developing the handheld devices that can be made portable and compatible with this capability. Very soon this satellites twin GSAT-6 A may be flown which will have even more powerful capabilities.
Nair says, "The government and ISRO should expedite development of GSAT-6 A to have special capabilities that the special forces need."
If one recalls in 2011, it was shown that President Barrack Obama monitored live feeds of the surgical strike the US carried out as part of Operation Geronimo to eliminate Osama bin Laden in Pakistan. India's GAST-6 and GSAT 6 A both will in principle be able to help providing live signals from the remotest of remote places in India's neighbourhood.
Sources in India's Aerospace Command confirm that they did have access to a live feed that was put in place using typical Indian 'jugaad' but with these satellites such capabilities will become common place.
Nair says right now India relies heavily on using Thuraya handsets for satellite telephony but he hopes very soon the Defence Research and Development Organisation will be able to deliver Indian handsets that are compatible with the country's GSAT-6 satellite.
In fact, Nair insists that in the upcoming GSAT 6-A, satellite telephony should be made the bigger component.
While understandably much of the resources are focused on land since India has hostile neighbours both on its western and eastern fronts. ISRO has not forgotten the deep blue oceans that surround India and they need to be protected as well.
On a specific demand by the Indian Navy, the Indian space scientists have already deployed a satellite the Navy calls 'Rukmini'. This is a dedicated communications satellite which helps the Indian Navy talk to its ships when they are beyond the visual range, in a secure fashion.
In coming years, ISRO will also deliver a dedicated satellite made for the Indian Air Force.
The author is a writer on science subjects for the Press Trust of India.
1. SC160 stage will carry 50 tons of more propellants than the L110 stage.nachiket wrote:I'm a bit confused regarding the SCE-200 replacing the MKIII 2nd stage. One SCE-200 is going to replace the twin-Vikas 2nd stage on the Mk3 right? So that would increase the total thrust of the 2nd stage by about 400kN. Is this change by itself supposed to increase the max payload by 2 tonnes? Sounds like a lot, but then I'm a layman in these matters.
As Indian Satellites are going into 6 ton category, I think Ariane launches will continue to be used as a complementary resource till atleast 2025.Varoon Shekhar wrote:"Hell..how long is ISRO going to use Ariane. I was hoping this would be the last foreign launch of Indian sats."
Probably 3 or 4 more. I guess a lot would depend on how successful the initial GSLV mark 3 launches are, and how quickly they can get the Mark 3 vehicles ready i.e the frequency or turn around time.
Gagan wrote:The two sats to be launched by Arianespace: Sky Muster II for the Australians, and GSAT-18. Just look at the number of antennae and dishes on the sat for the Aussies (SSL1300 Platform built in California)
Sky Muster II
GSAT-18
Looks like a misquote. Surely not the SC stage being flight tested even before a hot test on ground.The stage test of semi-cryogenic engine for the GSLV-Mark III would be flight-tested in December.
Are we not hitting Q4 2016 for GSLV MK 3 launch?bharats wrote: LMV3, a full-fledged vehicle will be launched in the first half of 2017. Mr. Rao said the heavy launch capability launcher would enable ISRO’s self-reliance in launching of satellites. It will send four tonne class geosynchronous satellites into the orbit.
http://economictimes.indiatimes.com/new ... 208700.cmsCHENNAI: Based on last year's GSLV Mark III's experimental flight, modifications have been done to solid rocket S-200 motors to change dynamic pressure and forces and ground tests have been done, a top ISRO official said today.
Stating that ISRO was planning to launch GSLV Mk-III by December next year, he said,"for GSLV Mark III launch the target is December 2016 and a second launch December 2017."
“The preparations of various stages of GSLV-MkIII are on in full swing. The first stage, comprising solid boosters, are ready and the integration the stage with the rocket has already started,” he added. The second stage —liquid stage —is also ready. Developmental activities in respect of the CUS (third stage) are in final phase,” Dr Kunhikrishnan said, adding, “We will be starting the mock trials shortly.” “The launch will be by the end of this year,” he said.
