SSLV News, Discussions, Updates and Reports

Varoon2

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Nice to see these mission videos return, after a 3 year absence! Just a cautionary note, the developmental flights of all but one of ISRO's satellite launchers failed on their first attempts. The SLV-3, the ASLV, the PSLV, the GSLV Mk1, the GSLV Mk2 all snagged somewhere, causing a failure. The GSLV Mk3 was successful on its first mission, let's hope the SSLV-D1 becomes the second vehicle to become a first time winner! :)
 

pipebomb

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Does anyone know how is active altitude control system is different from pitch control system of gaganyaan CES

And what is minimum ECLSS means
IMG_20220806_220331_944.jpg
 

DumbPilot

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It looks like 4th stage failed. 4 th stage must burn atleast 20sec...but here it burned only 0.1 sec....also I think there is some uncontrolled tumbling in 4th stage.
From what I understand the VTM(4th stage - Velocity Trimming Module) is more of a fine-tuning thing. It can be possible that the guidance computer thought that the orbit achieved by the previous 3 stages was precise and only fired the VTM for 0.1 sec. It's the only stage of the launch vehicle that can be turned on and off at will, unlike the rest of the three solid rocket booster stages.

Either way, we'll get to know once the satellite passes overhead once again
 

notaname

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Looks like satellites have not been placed but all stages worked normally, data loss was there so now need to wait for confirmation.
____________


SSLV-D1/EOS-02 Mission: Maiden flight of SSLV is completed. All stages performed as expected. Data loss is observed during the terminal stage. It is being analysed. Will be updated soon.

 

jai jaganath

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Looks like satellites have not been placed but all stages worked normally, data loss was there so now need to wait for confirmation.
____________


SSLV-D1/EOS-02 Mission: Maiden flight of SSLV is completed. All stages performed as expected. Data loss is observed during the terminal stage. It is being analysed. Will be updated soon.

So mission has failed ?
As info only 1 sat was placed in right path
 

Master Chief

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Looks like satellites have not been placed but all stages worked normally, data loss was there so now need to wait for confirmation.
____________


SSLV-D1/EOS-02 Mission: Maiden flight of SSLV is completed. All stages performed as expected. Data loss is observed during the terminal stage. It is being analysed. Will be updated soStage
This looks like ISRO cope.. If there was data loss at the fourth stage, how have all stages performed as expected..?
 

DumbPilot

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I can be wrong on this but I think it successfully inserted into orbit.

ISRO graphs are relative velocity:
1659850815327.png


1659850796987.png


According to this the SS3(stage 3) cut off at ~7.3km/s of relative velocity.

But in reality you need ~7.69 km/s of absolute velocity to sustain a circular(if ISRO is attempting a circular) orbit of ~356km.

But since ISRO's graphs are relative velocity, they are not taking into account the speed gained by rotation of the Earth => which, at 0° inclination(or along the equator) is 460m/s.

However the satellite is inserted at an inclination of 37°, so by multiplying:

460 x cos(37) => 367.3m/s => 0.36km/s.

So the absolute velocity of the satellite is 7.3km/s + 0.36km/s => 7.66km/s, which is only off by 30m/s to maintain a circular orbit. If they don't go for a circular orbit, they can probably still maintain something like a 356 x 120km~ orbit, at that speed.

After SS3 separation, the VTM fired for about 0.1 seconds =>

Weight at that point: 143kg.
Thrust: 800N
Duration: 0.1 seconds

Force = Mass.Acceleration => 800 = 143.Acceleration
=> 5.5m/s^2 acceleration.

=> 5.5 * 0.1 => 0.5m/s gained, and then the VTM stopped firing.

So the final orbital speed is somewhere around 7.66-7.67km/s.. so we'll see what happens. If there is an orbit, we should see a statement from ISRO. Otherwise it already burned up somewhere around Australia at around 10:20am 😛
 

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