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#80 by antriksh on 19 Aug, 2013 03:13
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Regarding the assembly of the launch vehicle in the Vehicle Assembly Building and its subsequent transport to the launchpad on that slow crawler -- is this all necessary?
Why not just mount the building and launchpad on rail tracks to shift them in or out of the way, while leaving the launch vehicle stationary? Seems to me that these large structures are less critical than the launch vehicle itself, and so they could be shifted more rapidly and less gingerly without having to use a slow crawler type of pedestal.
Thats what the FLP is ,i.e., Integration on Pad. This limits the use of pad by one VAB only. SLP is Integrate Transfer and Launch (ITL) and will allow
VAB and SVAB to share the SLP and the upcoming TLP. -
#81 by seshagirib on 19 Aug, 2013 03:49
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status update ( http://isro.org/ ) : propellant loading of 2nd stage in progress.
status update:
- 2nd stage propellant loading completed.
- strap on propellant loading in progress.
update:
- 2nd stage propellant loading completed.
- strap on propellant loading completed. -
#82 by input~2 on 19 Aug, 2013 04:46
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Live webcast from 1045UTC on http://webcast.gov.in/live
(also tentatively on http://216.185.104.74/isro) -
#83 by seshagirib on 19 Aug, 2013 08:22
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status update ( http://isro.org/ ) : propellant loading of 2nd stage in progress.
status update:
- 2nd stage propellant loading completed.
- strap on propellant loading in progress.
update:
- 2nd stage propellant loading completed.
- strap on propellant loading completed.
update:
cryogenic propellants loading in progress. -
#84 by vyoma on 19 Aug, 2013 08:25
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status update ( http://isro.org/ ) : propellant loading of 2nd stage in progress.
status update:
- 2nd stage propellant loading completed.
- strap on propellant loading in progress.
update:
- 2nd stage propellant loading completed.
- strap on propellant loading completed.
update:
- Third Stage Cryogenic Propellant filling operation is in progress.
- Propellant filling operation of First Stage Strap-Ons is completed. -
#85 by AJA on 19 Aug, 2013 08:46
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In before this becomes an update thread for the day.
The Coolest Hot Engine!!!!!
OK.. so from the video, and the brochure, this is what I've managed to corral about the CUS.
Length: 8.7 m
Diameter: 2.8 m
Prop: LH2/LOX (Typical Isp of combination - 450 s)
Propellant Mass: 12.8 tonnes
Max Thrust: 75 kN
Nominal thrust: 73.55 kN - including thrust from the 2 gimballed steering engines on the stage (Separate engines, or is the gas generator exhaust being used for this a la Merlin? The fact that the brochure says that the Main engine has 200s of test time and the steering has 100s makes me think these are hypergolic verniers. If it was the GG exhaust, the steering would've had ATLEAST the same run time as the main. Having said that, the animation shows a separate off axis gas generator exhaust, so that's probably used too.)
Nominal Burn time: 720 sBallparkCricket-stadium Isp (assuming uniform mass flow rate for 720s) : 430.2 seconds ...Hmm..
The nozzle has a jacket for cooling, and propellant (LH2/LOX?) pre-heating. The stage also has a bell extension. Pretty standard.
Individual booster pumps for LH2 and LOX, feeding a main turbo-pump running at 40,000 rpm. Thrust control and mixture ratio control possible through two regulators.
I've got a few questions:
1) Thrust control through mixture control? As opposed to throttling both flow rates up/down proportionally to maintain optimum combustion ratio (and conserve propellant)? Does this optimum ratio change through the course of the flight (I'm thinking residual atmospheric oxygen - thinning out with height)
2) The Mahendragiri test video grabs showed a orange/red/yellow flame... Hydrogen burning produces a blue flame doesn't it - regardless of mixture ratio? I mean it's not like there's a partial combustion product for the reaction? The flame was fidgety too.. now I'm not saying they don't have stable combustion - we might have been seeing transients - but it definitely was dancing.
3) What the heck is happening at 7:58 in ? Something's inflating?
4) Like most modern cryogenic stages, the LH2 tank is physically removed from the LOX tank, with an air-gap present between them. Can someone explain why? I thought the second stage of the Saturn V implemented a great solution in realising a common bulkhead ( - PS: 1:35 is AWESOME
) The video explicitly mentions it for good measure, but I would've thought anyway - that the steeper thermal gradient would've been between either fluid and the ambient air. Also surprisingly for something that's meant to be kept cool, the tanks are painted black!
5) The video showed the cryo prop-depot enclosure, but the shots of the launch pad don't seem to. How far away is it from the pad? I guess it would be desirable but is it even feasible to have a mobile cryogenic tanker? Related: has anybody here ever been to SDSC? Does ISRO conduct a guided public tour – for students/educational institutions atleast? (Or do they share Kanaka's paranoia?
)
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#86 by Chris Bergin on 19 Aug, 2013 09:48
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Here's William Graham's excellent launch overview/preview:
http://www.nasaspaceflight.com/2013/08/indian-gslv-launch-gsat-14-communications-satellite/ -
#87 by Chris Bergin on 19 Aug, 2013 10:15
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L-65 mins. Best webcast link would be appreciated.
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#88 by seshagirib on 19 Aug, 2013 10:29
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L-65 mins. Best webcast link would be appreciated.
government news channel:
http://webcast.gov.in/live/
is likely to carry the launch webcast, but cannot say much about the quality. -
#89 by tehwkd on 19 Aug, 2013 10:33
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L-65 mins. Best webcast link would be appreciated.
With ISRO launches, the best one is usually whichever opens for you
http://webcast.gov.in/live/
http://ibnlive.in.com/livetv/
http://live.indiatimes.com/
http://www.ndtv.com/video/live/channel/ndtv24x7
http://216.185.104.74/isro -
#90 by input~2 on 19 Aug, 2013 10:40
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Hindustan Times @htTweets Isro halts countdown of GSLV rockets due to a leak: TV reports #ht
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#91 by tehwkd on 19 Aug, 2013 10:40
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#92 by AJA on 19 Aug, 2013 10:41
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SCRUB!Reporter said "Hold"
The news ticker's showing: "ISRO calls off scheduled GSLV-D5 launch due to technical reasons"
Smoke emanating from the 2nd stage, during the cryo-tanking.
A press meet (with the chairman of the review board) is scheduled in a short while from now apparently, which makes me think it's a scrub. -
#93 by Galactic Penguin SST on 19 Aug, 2013 10:43
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Was it a scrub for the day?
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#94 by tehwkd on 19 Aug, 2013 10:44
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#95 by Chris Bergin on 19 Aug, 2013 10:44
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Well that's a scrub then.
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#96 by input~2 on 19 Aug, 2013 10:44
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#97 by albatros68 on 19 Aug, 2013 10:46
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Was a new launch date scheduled?
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#98 by input~2 on 19 Aug, 2013 10:47
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Quote
LAUNCH WINDOW FOR THE REMAINING PERIOD FROM 20TH AUGUST TO 5TH SEPT 2013 SHALL BE KEPT ALIVE FOR RESCHEDULING OF LAUNCH IF REQUIRED.
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#99 by AJA on 19 Aug, 2013 10:50
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Right, there's a press meet on with the ISRO Chairman - as soon as the room settles down.
"Countdown progressed well, and a few minutes ago, we observed a leak in the fuel system of the second stage of the vehicle, and because of this we are calling off the launch"
"Our teams have been put on action to drain out the liquid propellants from the 2nd stage, the four L-40 strap-ons and the Cryogenic stage. Soon after that, we will move the vehicle to the VAB, and we need to make an assessment of the cause of the leak, and what are the actions that we need to take before further preparations for the launch."
No launch today.
Says they need to meet with the team to review the data, and then decide on a new date.
EDIT -caught this on a replay of the interview: In response to a question, ISRO Chairman the leak was detected "just 2 hours before liftoff."
Inaudible question : Someone replied that the problem was detected after LOX loading was complete, and just as they were starting LH2 filling. He also clarifies that this has nothing to do with the leak in the 2nd stage.
) The video explicitly mentions it for good measure, but I would've thought anyway - that the steeper thermal gradient would've been between either fluid and the ambient air. Also surprisingly for something that's meant to be kept cool, the tanks are painted black!
)