Search found 516 matches

by Haridas
20 Sep 2019 22:46
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

ramana wrote:Haridas if the control system failed its effectively open loop no?.
when multi actuator, multi variate, control loop fail it is much worse than open loop control.
by Haridas
20 Sep 2019 21:44
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

UB saar, the composite image is by stitching images on multiple passes, Under similar lighting condition. The cylindrical artifact is due to stitching scaling errors from adjoining image patches.
by Haridas
20 Sep 2019 21:32
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

That spreadsheet calculation gives out boundries for an open loop system. There is no evidence of IMU (inertial measurement unit) malfunction (it's any way very very unlikely). So engine thrust mismatching will be easily cancelled out by close loop control. IMHO the close loop control will fail if :...
by Haridas
17 Sep 2019 11:32
Forum: Military Issues & History Forum
Topic: HTT-40 Basic Trainer Aircraft: News & Discussions - 08 September 2019
Replies: 87
Views: 13712

Re: HTT-40 Basic Trainer Aircraft: News & Discussions - 08 September 2019

Gyan wrote:Would HTT40 be useful for CAS in mountains due to its slower speed & better turning radius compared to jet aircraft or vulnerable helicopters?

Unpredictable tempest type winds (strong downdraft) of mountains make light & slow HTT40 a less useful craft, even unnecessary risk.
by Haridas
17 Sep 2019 11:23
Forum: Military Issues & History Forum
Topic: UAVs, Drones, Remote Surveillance Tech
Replies: 2258
Views: 428638

Re: UAVs, Drones, Remote Surveillance Tech

DRDO`s unmanned aircraft Rustom 2 crashes in Karnataka`s Chitradurga
Zee Media Bureau Sep 17, 2019, 09:57 AM IST,

https://zeenews.india.com/india/drdos-u ... 5.html/amp
by Haridas
16 Sep 2019 21:28
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

After thorough testing & confirmation of logic in C etc, final coding is converted to manually written machine code embedded in Space qualified ROMs/PLAs. Wow hearing about PLA after so many decades. Almost forgotten it existance. I built my redundent INS & Flight control system in IIT dill...
by Haridas
14 Sep 2019 20:57
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Ramana Sir, I share your thoughts. Trajectory started showing significant deviations soon after the initiation of transition. But my doubt is, that if 800N engines had variable thrust capability, why were only two diagonal engines used for fine braking instead of lowering the thrusts of all four en...
by Haridas
14 Sep 2019 20:38
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Since we dont have a Orbiter, can we send 2 Landers? one are the equatorial plane, and the other at South pole. Both of them can communicate via CY2. Let FAC do their thing and ISRO plan for the new lander. Still need a bus to carry the lander and then de orbit. Why is bus necessary? The lander has...
by Haridas
12 Sep 2019 12:17
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

I assumed its sec:hundredths of second. Usually telemetry is in millisecs that is reported as Secs: xxx So here they are reporting as secs: 0.xx0 Eg. 19 Secs 550 millisecs, 20.000, 20 secs 050 millisecs They probably have better data but the graph divisions are like that Hours minutes is very slow....
by Haridas
11 Sep 2019 10:56
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Except the range safety officer. He sure will have the red button! Back in 1989 I was working with xxx for range safety computer that can communicate with a dozen different optical sensors types at far off places on specialized serial like interfaces. Computation speed was limited due to US embargo...
by Haridas
10 Sep 2019 21:16
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

No sir. It corresponds to power inputted into the radio receiver input by the the receiver's high gain dish antenna. It depends if you measure prior to down conversion, as you said, or the IF power. It's not clear from DSN. It's a radios rating, always corresponding to signal level seen at its inpu...
by Haridas
10 Sep 2019 21:12
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

2. With a 30 footer , the monn's radiation ( Sun Noise reflected by whole Moon disc ) is in the range of -106 to -108 dbm on Full Moon day. So what was seen as -114dbm etc is the radiation noise ... not signal. It is about halfway between Full Moon and Amavasya. Beg to differ, carrier can be dug up...
by Haridas
10 Sep 2019 12:54
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Mort sir they have to look at the received tone characteristics before they request data Yes, I guess they're just looking for a carrier. No data is being sent up. In extreamly poor Signal to Noise ratio (SNR) signal (often due to link budget exhaustion) one can reduce the receiver bandwidth to few...
by Haridas
10 Sep 2019 12:37
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

SSSalvi wrote:What is 6 axis?
abelity to measure 3 orthogonal linear axis and 3 orthogonal rotational axises.
by Haridas
10 Sep 2019 12:36
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Pingreji pls: what is an up signal and what does -141 dB mean? Compared to 1 watt? And is that the source (because receiver power should depend on solid angle of capture), hain? Like if I got this much power with this much area, and I know it came from this source, then the omni-directional source ...
by Haridas
10 Sep 2019 12:24
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

chetak wrote:would anyone know if the stabilization system is 3 axes or 6 axes

All such flight control systems have to be at least 6 axis stablized.
by Haridas
10 Sep 2019 12:01
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Need a NG&C expert here. The AIAA paper says in 2nd para page 5, that The INS after updating the state vector is used for the first burn. During the long coast phase also, the attitude and gyro drifts are updated using star tracker. The accelerometer bias is also updated during the long coast p...
by Haridas
10 Sep 2019 11:54
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

All these say that it is recoverable when the sun is sufficiently up (over the next week!) But if the comms are destroyed, then it cannot be instructed to correct itself. So the original comm failure is still the big catch. There HAD to be one more error after the fully automatic system took over, ...
by Haridas
10 Sep 2019 11:28
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

I have been ignoring Ulan Batori's posts Someone could perhaps show this postor how to use the "ignore" key and how to operate it so that she does not ever again sully a friendly discussion with her sneering. Some of us are humble yak-herders, we didn't memorize high-school textbooks.. bu...
by Haridas
10 Sep 2019 11:00
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

UBCN diagnosis (posted b4) of "Too Much Thrust" (on one thruster was the quote) means combustion instability. Liquid fuel is metered through a choked nozzle with sufficient pressure ratio to prevent feedback from the combustor to the fuel source. So it is probably not because of too much ...
by Haridas
10 Sep 2019 10:42
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Paper says that CY-1 (not CY-2) was forced to raise orbit from 100km to 200km to reduce heating. Is this radiant heat from lunar day? Wow! I thought it only reached 200C which should cause radiant heating only like an average day in Sriharikota summer, hain? Doesn't the orbiter rotate to distribute...
by Haridas
09 Sep 2019 07:46
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

UB, They are using hypergolic liquid fuel and can be precisely metered by a valve. I think the current draw is monitored to give status. But recall it takes > 2 minutes for signals to go back and forth Control software shouldnt use fuel consumption based thust estimation, but by directly measuring ...
by Haridas
08 Sep 2019 11:19
Forum: Strategic Issues & International Relations Forum
Topic: Terroristan - May 1, 2019
Replies: 1925
Views: 327268

Re: Terroristan - May 1, 2019

So they do not want our President to overfly their territory because of 'atrocities' etc. But they are importing life saving medicines. What happened to the atrocities then? Modi should impose 100% tariff on these medicines. Let us make some money too. Tarrif is on imports. U R saying lay a tax on ...
by Haridas
08 Sep 2019 01:42
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Gagan wrote:Maybe they can fire the rockets to straighten and stand it up!

I see Incorrigible optimism 8) not grounded in reality.

No signal transmission means irrecoverable.
by Haridas
08 Sep 2019 01:27
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

No Pallav Bagla needs to pay for his arrogance He should be shadow banned by ISRO and GoI for an extended period Even when he was "doing so much for Indian science" he was slyly asking single digit IQ marxist type questions, like how do you justify a space program when India is so poor, a...
by Haridas
08 Sep 2019 01:15
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Well then now is the chance, right? The "Ghastly Trolls" should now dig up old footage of the Bagla's antics and put it up for all to see how much he has "done for ISRO." That Doppler curve shows steady deceleration during the rough braking phase. If the craft were tumbling then...
by Haridas
07 Sep 2019 23:00
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

The whole purpose of Vikram and Pragyan was to determine water if there was water in the lunar soil and H3. This science discovery was a loss not just for India, but the whole of humanity. I will respectfully diss the veteran Expert who said that yesterday during the run-up on Republic TV. Probably...
by Haridas
03 Sep 2019 03:19
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Still wondering about video of these events. What limits real time transmissions. Weight penalty, power management, transmission bandwidth? HD video requires few Mbit/sec bandwidth. Similar to Geo Sat satellite that are very heavy compared to orbiter. Now the distance is 10 times more, so link budg...
by Haridas
03 Sep 2019 02:59
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Amber G, ISRO is known for what it has achieved. So are the isotopes the only way to get power? I understand the power source has to be light in weight. So I am not wondering why we not have a giant battery pack. Battery has to be recharged and where and how will the recharging happen = from Solar ...
by Haridas
03 Sep 2019 02:33
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

^^^Yes, I remember playing with some isotopes as an undergraduate that were primarily alpha emitters, But I didn't know that Pu238 had no gammas . I would still think any RTG would create noise in radio transmit-receive, as many digital transmissions are near thermal noise levels at a given bandwid...
by Haridas
25 Aug 2019 13:35
Forum: Technology & Economic Forum
Topic: Om Shanti: Shri Arun Jaitley Shradhanjali
Replies: 37
Views: 2321

Re: Om Shanti: Shri Arun Jaitley Shradhanjali

RKumar wrote:BJP is losing senior leadership... MP, SS and now AJ.

RIP sir and God may give long life to others.

Saar please see this tweet
https://twitter.com/HaridasKukkur/statu ... 67680?s=19
by Haridas
25 Aug 2019 13:30
Forum: Technology & Economic Forum
Topic: Om Shanti: Shri Arun Jaitley Shradhanjali
Replies: 37
Views: 2321

Re: Om Shanti: Shri Arun Jaitley Shradhanjali

Arun Jaitly ji served mother Bharat well.
Bhagwaan unki atmaa ko sad-gati devey.

Shat shat naman.....
by Haridas
18 Aug 2019 10:30
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 3969
Views: 829165

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

Just to clear up for lay people like myself :) - there is no perigee and apogee with Chandrayaan-2 at this time, right? It is headed straight for the moon. Then there is the 'lunar capture', which leads to a new set of perigees and apogees around the moon, until it sets in at a more or less 100km o...
by Haridas
12 Aug 2019 21:20
Forum: Military Issues & History Forum
Topic: Indian Missiles News & Discussions - 17 Dec 2018
Replies: 1688
Views: 430872

Re: Indian Missiles News & Discussions - 17 Dec 2018

Any particular advantage/disadvantage of MMW vs Ku-band seekers? 1) Wiki tells me that MMW seekers suffer more atmospheric attenuation. Is that why they're not preferred for A2A or SAM applications? 2) If so, why is MMW preferred for an ATGM role vs Ku-band? Better resolution? mmW seeker is ideal f...
by Haridas
07 Aug 2019 01:47
Forum: Strategic Issues & International Relations Forum
Topic: RIP - Sushma Swaraj ji
Replies: 54
Views: 3356

Re: RIP - Sushma Swaraj ji

Dhanyawaad Sushma ji for serving Maa Bharati.
May you reach your next karma bhoomi with greater glory.

Sushma ji proudly called herself beti of Braja bhumi.

Hare Krishna Hare Krishna, Krishna Krishna Hare Hare ......
by Haridas
05 Aug 2019 06:41
Forum: Military Issues & History Forum
Topic: Indian Missiles News & Discussions - 17 Dec 2018
Replies: 1688
Views: 430872

Re: Indian Missiles News & Discussions - 17 Dec 2018

My guess is that R-27 are IR guided long range missiles perhaps with datalink, 100km?. Though can be ultra long range RF seeker missiles, 170km? IAF always had interest in VLR BVR AAMs since 1980s. But Pak will also get something equivalent from China We need to invest in other aids like DIRCM, Sat...
by Haridas
05 Aug 2019 06:31
Forum: Military Issues & History Forum
Topic: Indian Missiles News & Discussions - 17 Dec 2018
Replies: 1688
Views: 430872

Re: Indian Missiles News & Discussions - 17 Dec 2018

I think its homegrown - might even be the same MMW seeker as that of Akash-1S IIRC first candidate for mmW seeker is for Nag missile. Is there any news of the mmW sensor being ready for test or close to deployment on any missile? Akash-1S is with seeker/sensor, but I am sure it is not mmW seeker ye...
by Haridas
25 Jul 2019 12:24
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Thanks, HDji. I think the point I was missing is that the cryo stage burn is fairly long and that you want to finish the burn and chuck the engine ASAP, not carry it to great heights. Mental orbital mechanics is not up to figuring out the effect of a burn when it is not completed at perigee. I supp...
by Haridas
24 Jul 2019 21:55
Forum: Military Issues & History Forum
Topic: Indian Naval Aviation
Replies: 906
Views: 141210

Re: Naval Tejas Mk1/Mk2: News & Discussion - 23 February 2019

[ Technology F-18 is a 1970s plane with lipstick on it. its the loser of the F-16 light weight fighter and was called F-17. The USN decided they will take it and navalize it. And became the F-18. Ramana, some corrections to factual inaccuracies. ........... .. Saar you are carrying coal to castlefi...
by Haridas
24 Jul 2019 21:35
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1996
Views: 217119

Re: Chandrayan-2 Mission

Goat herder garu, what you say is for mard e momin cryo stage, but engineering wise the max payload is always for most optimised weight of upper stage using this type of lofted trajectory allowing cryo stage time to deliver it's deltaV. Recall the gslv mk1/2 CUSP has two thrust settings, second lowe...

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