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by prasannasimha
29 Jul 2019 22:47
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 4390
Views: 1066822

Re: Indian Space Program: News & Discussion - Sept 2016

Dr Sivan clearly mentioned that they will test the SSLV only after Chandrayaan's touch down on the moon. Probabaly enough human resources need to be diverted to Chandrayaan that SSL:V launch took a backburner.
by prasannasimha
29 Jul 2019 22:10
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Enough fuel saved with the preliminary launch injection is such that Chandrayaan's life may be extended by a year (to two years) if all subsequent burns are nominal At the end of all Earth-bound and lunar-bound manoeuvres, the orbiter should be left with at least 290.2kg of fuel when it is in the 10...
by prasannasimha
29 Jul 2019 21:40
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 4390
Views: 1066822

Re: Indian Space Program: News & Discussion - Sept 2016

GSAT hall thruster is developed in house. As far as the SE200 it has been developed and awaits an aproproiate test stand for firing. This is being constructed. You would not do a firing test of a stage without the engine
by prasannasimha
28 Jul 2019 22:51
Forum: Military Issues & History Forum
Topic: India's R&D in Defence DRDO, PSUs and Private Sector
Replies: 4327
Views: 758291

Re: India's R&D in Defence DRDO, PSUs and Private Sector

The large unfurlable antennae are basically for communication or intelligence purposes. NRO has 300 feet large deployable antennae !! ISRO launched a 6 M one and the largest ones in private sector are by Hughes telecom. To allow larger antenna placement in the payload faring we will need a 5 meter f...
by prasannasimha
28 Jul 2019 21:14
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Third earth bound maneuver for Chandrayaan 2
29.07.2019

14:30 - 15:30 IST

268 x 71558 Kms
by prasannasimha
28 Jul 2019 10:22
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 4390
Views: 1066822

Re: Indian Space Program: News & Discussion - Sept 2016

Please divert all ion engine/electric propulsion discussions here and not to the Chandrayaan thread> FWIW https://forum.nasaspaceflight.com/index.php?PHPSESSID=n4uqs9686p7mmfn2gvqnqtdjjp&action=dlattach;topic=33770.0;attach=1498864;image http://lh3.googleusercontent.com/-J2Ga77edadY/ViSObNdCdvI/...
by prasannasimha
28 Jul 2019 09:58
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

.UB if you think tha ISRO is simply hatching eggs - you are wrong and they are doing work on ion thrusters and that you do not know about it is your problem.They have developed working Hall thrusters that are being deployed FYI and work is going on wrt other ion thrusters and electric propulsion dev...
by prasannasimha
27 Jul 2019 20:40
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Gee! The Thought Polis are out in force, time to exit to caves. Might as well tell us to shut brain off and use narrow-vision blinders. Back to watching Republic TV blabber, thanks very much. The Moon looks soooooo pretty, no? No one has policed anything = just discuss this in another appropriate t...
by prasannasimha
26 Jul 2019 23:26
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Yes this thread is being sidelined. Please shift ion engine discussions toi ISRO thread
by prasannasimha
26 Jul 2019 13:53
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 4390
Views: 1066822

Re: Indian Space Program: News & Discussion - Sept 2016

SC 200 cold flow tests etc were over long back. The test stand for hot firing is being constructed at IPRC and when complete testing will occur. There was some plan to test in Russia but that seems to have been shelved
by prasannasimha
26 Jul 2019 11:40
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Ion engines can be used for say GTO to GSO or GEO transfer. They would provide significant weight penalty advantge. Howrver thete are dtill a lot of issues with ion engines that have to be smoothened out. Thats why they are not still widely used and only a few missions have acruslly used it. The Ris...
by prasannasimha
25 Jul 2019 23:23
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Even there only 94%
by prasannasimha
25 Jul 2019 23:01
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

As far as I know due to libration and tidal locking there is no portion of the moon that is not lighted at some time ie no part under permanent darkness.
by prasannasimha
25 Jul 2019 21:24
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

SSSalvi pictures did not come through
by prasannasimha
24 Jul 2019 21:49
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 4390
Views: 1066822

Re: Indian Space Program: News & Discussion - Sept 2016

How does a Falcon 9 weigh 550 tons when it can lift more payload than GLSV Mk III when it weighs 640 tons? Disha, that above may tell you that SpaceX's approach to clustered engines may be more bang on target since it is more efficient than GLSV Mk III? The reason is different - the ISP of the semi...
by prasannasimha
24 Jul 2019 21:44
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Becoz with the relatively underpowered cryo stage, the ISP loss due to gravity is minimized by lofting the upper stage higher then targeted perigee, the C25 is angled for imparting more of tangential velocity (that result in greater centrifugal force, thus minimising need for radial lifting force t...
by prasannasimha
23 Jul 2019 19:36
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

You Tube's own editor is good ... You can cut/move and give textual highlights. Not very cumbersome to grasp the nitty gritties. My mistake should have been specific, the video is 4GB in size. Its 4K video shot with a professional camcorder. The size makes it difficult for me to upload and edit it ...
by prasannasimha
23 Jul 2019 19:36
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

TV coverage was awful because only DD is allowed to live telecast from launch control facility and launch pad. At least 2 private TV channels must be granted access proving they have state of the art 4K HDR television cameras. Let some competition come in and even DD will improve. The private TV ch...
by prasannasimha
22 Jul 2019 23:06
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

sanjaykumar wrote:There is no such thing as 'over performed' in engineering. Either it is to design parameters or it is not.

The burn was "burn to depletion" allowing a higher apogee.
by prasannasimha
22 Jul 2019 15:43
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Apollo11 got to the moon and back in 8 days. so why is our chandrayaan only getting to the moon in 48 days in early september. was it because they used the huge Saturn5 rocket to make a direct beeline for the moon instead of slowly doing orbit raising manouvers ? 48 days would have needed a lot of ...
by prasannasimha
22 Jul 2019 15:41
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Not just that but net weight injectable woyld be less with direct TLI to moon with GSLV
by prasannasimha
21 Jul 2019 23:33
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

UH25 (fuel) filling of liquid core stage (L110) of #GSLVMkIII-M1 completed
Updates to continue...
by prasannasimha
20 Jul 2019 22:42
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

I had talked to an ISRO engineer and he said that the early stages have to drop of early (They could be designed to work for a longer time) but the constraint for them is that they have to fall off in safe zone leaving the Cryogenic stage to do a lot of firing. It can impart the delta V earlier than...
by prasannasimha
20 Jul 2019 20:17
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Image

See the very long firing of CE 25 in a previous launch
by prasannasimha
20 Jul 2019 20:00
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Since the launch date was changed the major thing that needed to be changed is the duration of scouting of the chandrayaan vikram praguyaan complex in the 100x100 orbit so that descent occurs 7 days "earlier" than originally planned (ie same day since we launched late) to allow pragyaan to...
by prasannasimha
20 Jul 2019 17:04
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

All equatorial or near equatorial plane launches have to be adjusted such that there are no spent stages etc dropping over inhabited land masses. Importantly Indonesia etc
by prasannasimha
19 Jul 2019 08:20
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Why is a helium tank used on cryogenic engine Ullage space pressurization is least important as fully cyogenic engine is self pressurizing by its very nature. It is required for engine spin start and precooling the engine prior to propellant flow as the LOX and LH2 should be in liquid state when pum...
by prasannasimha
18 Jul 2019 19:34
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

There are reasons for SRB's to be fired first in GSLV - they provide the maximal bang for buck cost wise while traveling through the dense atmosphere as they are fuel dense. One we cross Qmax (period of maximal atmospheric resistance to the vehicle )the L110 fires (I have to be corrected wrt to that...
by prasannasimha
18 Jul 2019 00:15
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

The cryogenic stage is actually self pressurized so if the Hrlium tank failed the mission **may** have still been succesful ( the annoyncements from ISRO sort of confirm it). However they havevused Helium aa ullage pressutizing ahent as precaution or some specific reason so they qould not like to ta...
by prasannasimha
16 Jul 2019 07:01
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Helium is used to pressurize ullage space to ensure pgopellant is flowing ptppefly in zero gravity. They will have standard parameters for these.
by prasannasimha
15 Jul 2019 14:55
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Please stick to discussion. The very nature of a countdown is for actual system checks and has happned in many space launches. In the last year itself multiple launches of various countries had to be scrubbed. The probable cause here is the helium or main tank pressurization issue as per reports. In...
by prasannasimha
15 Jul 2019 02:55
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Confirmed . New launch date will be announced.
by prasannasimha
14 Jul 2019 23:52
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

This is an old video by NASA that explains it well

by prasannasimha
14 Jul 2019 23:00
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

The videos have become pretty slick. If you see the landing site video with full music and full screen it looks really good. short and striking.
by prasannasimha
14 Jul 2019 23:00
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

The videos have become pretty slick. If you see the landing site video with full music and full screen it looks really good. short and striking.
by prasannasimha
14 Jul 2019 22:57
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

by prasannasimha
14 Jul 2019 22:42
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Image
by prasannasimha
14 Jul 2019 22:35
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

so instead of circularing a highly elliptic launch orbit (for regular GSO sats) this time it will make the ellipse major axis longer & longer and then finally escape into the lunar transfer path. then reverse on other side to make ellipse into a circle before lander detaches. it will be a real ...
by prasannasimha
14 Jul 2019 22:33
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

Why are they launching at night? Got delayed to monsoon season so can’t really help overcast weather.... It is because of the argument of perigee and the timing needed to have appropriate translunar injection so there are every day certain launch windows and this has to correspond to land on day1 o...
by prasannasimha
14 Jul 2019 09:50
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 2274
Views: 341709

Re: Chandrayan-2 Mission

^ Small correction Republic TC will be relaying Doordarshan's feed.

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