Search found 75 matches

by prao
07 Jan 2011 23:04
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

I was thinking about the connectors some more and I realized that a seal like O-rings wouldn't be possible because it would make it difficult to connect the two halves together (the air inside would be resist compression). So a modified version of my theory is that after the halves were joined, the ...
by prao
07 Jan 2011 06:40
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

Ramana, I understand the mechanism. I am suggesting that the two halves of the joint enclose sufficient volume of air and form a tight enough seal. Tight enough that there is sufficient pressure force pushing them apart when the rocket reaches some altitude. Volume should be sufficient so that leaka...
by prao
07 Jan 2011 03:44
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

Here's some wild speculation about why the connectors separated: Pretty improbable I think but still who knows, worse mistakes have been made. What if the connectors chosen were: (1) new design - not flown before. (2) Did not have a positive lock (quite likely because they have to separate) (3) The ...
by prao
31 Dec 2010 21:21
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

An afterthought: ... If multiple connectors have snapped then it could be due to a rogue command impulse issued to their separation mechanism also. ... Regarding Self destruct command: A colleague who participated in assembly/evaluation of rockets at SHAR had told me that destruct command pulls a t...
by prao
21 Sep 2009 08:09
Forum: Nuclear Issues Archive
Topic: Pokhran II not fully successful: Scientist - Part-2
Replies: 2359
Views: 143845

Re: Pokhran II not fully successful: Scientist - Part-2

I'm not the mole says Arunachalam.

Now what did Nixon say? He said "I'm not a crook".
by prao
19 Sep 2009 21:51
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

I think I've been very clear about my opinion of the CY1 issue and why I think it's important. I'm sorry to say that some of you are missing the point and are addressing non-issues. If the causes of CY1's issues and early demise had been a purely technical issue, I would not have been so bothered. S...
by prao
19 Sep 2009 08:54
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

I think I've made it very clear that I consider CY1 a great achievement. Please read what I've said carefully.

Failures need analysis and you need to learn lessons from them. Closing your eyes to them only invites more failures.
by prao
19 Sep 2009 08:46
Forum: Nuclear Issues Archive
Topic: Pokhran II not fully successful: Scientist - Part-2
Replies: 2359
Views: 143845

Re: Pokhran II not fully successful: Scientist - Part-2

I hope this was not posted here before. I couldn't find it in the past few pages. Info about Santhanam by B. Raman in his inimitable point by point style with some interesting if uncomfortable questions for Santhanam. I've reproduced the full item here because it's all of great direct relevance to t...
by prao
19 Sep 2009 08:29
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

I do understand your point. my question was how can we be sure it is more than just an educated guess ? has ISRO said anything of the kind ? just curious. It is an educated guess, no doubt. And no it hasn't and I suspect that it won't since it may show them in poor light. I think what happened is t...
by prao
19 Sep 2009 08:00
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

The reason for the congestion of course is the MIP that was a late stage addition. the MIP was ejected almost as soon as CY-1 reached the moon. why do you think it continued to contribute to the heating problems via congestion ? what could have been the residual instruments left behind by it that w...
by prao
19 Sep 2009 06:55
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

From the Indian Express article: In fact, the decision to carry 11 payloads on Chandrayaan- I and whether it affected its thermal management is being actively debated. Scientists feel that had the spacecraft been less congested internal heat could have been more effectively ventilated. The reason fo...
by prao
16 Sep 2009 05:25
Forum: Trash Can Archive
Topic: China Military Watch
Replies: 3944
Views: 928384

Re: China Military Watch

Here's a good one. The Chinese are up to their usual games of (trying to) lulling the Indian side to complacency. This time their tactic is simply to get GOI to stop HH The Dalai Lama's trip to Arunachal Pradesh and muzzle the new found voice of the Indian media. The idea being to get the MEA to thi...
by prao
15 Sep 2009 05:24
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

A clear eyed analysis means that childish emotional/jingoistic outbursts have no place in the discussion. Throwing out a list of questions, creating straw men and calling the fine engineers of ISRO names are only childish attempts at stymieing open discussion about the topic. The reason for analysis...
by prao
14 Sep 2009 05:53
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

Returning to my earlier observation of ISRO protesting too much. I would like answers to two basic questions with regard to CY1: 1. Why did ISRO underestimate the radiation/thermal load at the design orbit of 100 km? Was it a lack of available information? (I'd think that with so many missions to th...
by prao
14 Sep 2009 05:30
Forum: Trash Can Archive
Topic: China Military Watch
Replies: 3944
Views: 928384

Re: China Military Watch

Now we hear of a " China Study Group " - a bunch of bureaucrats that's been putting restrictions on the army for a while by the looks of it. Restrictions of this kind only serve to weaken our claim on the border areas - quite simply if you don't assert ownership - by regular patrols, your ...
by prao
14 Sep 2009 02:12
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

I am really puzzled that ISRO has felt the need to recruit all and sundry to proclaim that CY1 was a 95% success. Has there been a backlash against ISRO after the CY1 mission was called off? I can't recall coming across anything on the web (no I didn't go looking for it - I dare say I could find it ...
by prao
13 Sep 2009 03:56
Forum: Mil-Tech Archive
Topic: Indian Space Program Discussion
Replies: 3966
Views: 553223

Re: Indian Space Program Discussion

This doesn't make sense to me. How do you replace something as crucial as a bus management unit at such short notice - that too on a spacecraft waiting to be integrated to the launch vehicle? Anything put on a spacecraft needs to be individually qualified which isn't a quick process. The failure of ...
by prao
11 Aug 2009 07:46
Forum: Trash Can Archive
Topic: Indian Naval Discussion
Replies: 3938
Views: 1035520

Re: Indian Naval Discussion

Admiral Mehta's motivation could be to galvanize public opinion in favor of building up India's military, space and cyberwar capability and hopefully cause a little strengthening of the spine of the civilian leadership. It will do India's public a little good, this little shocker. I think people rem...
by prao
22 Feb 2009 07:06
Forum: Trash Can Archive
Topic: Indian Space Program Discussion
Replies: 519
Views: 26184

Re: Indian Space Program Discussion

There is nothing "disrespectful" in Sanjay M's discourse. Such a questioning attitude is quite useful in the forum. Not only is it "useful" but it is absolutely necessary for the integrity of the forum. There can be no restrictions or rules, either written or unwritten, on what ...
by prao
06 Dec 2008 07:58
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

For orbital/fuel consumption etc calculation, simple calculation (using Newton's Mechanics) can give the rough amount of delt-V, energy (fuel -consumption etc needed) - basically energy of an (elliptic - stable) orbit depends on its semi-major axis -only- and if you need to calculate the change in ...
by prao
06 Dec 2008 02:30
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

The theoretical resolving power of an optical system is not really relevant to CY1 with regards to orbital changes, no? The thermal issue has to do with thermal radiation from the moon not the sun. Do you have any lunar radiation numbers that might tell us how it will increase at lower orbits? I thi...
by prao
05 Dec 2008 23:18
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

How about an asteroid intercept if one is around? That should be exciting no? If requirements are reasonable (1st calculation to perform - 440 N? thrust, fuel specific impulse, available fuel ..?) all sorts of things can be tried.
by prao
05 Dec 2008 20:00
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

Something half as far away will appear twice as big. A 5 m object that was one pixel wide will be two pixels wide - hence 2.5 m resolution (approximately). It is an approximately linear relationship between the inverse of the distance and the size. However, you'll see four times the detail - conside...
by prao
05 Dec 2008 08:14
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

Due to communication time lag between earth and moon, the final descent to and landing on the moons surface has to be autonomous. I suppose this would require non trivial re-configuration of the yaan's mission profile and therefore unlikely. De-orbiting to lower altitute seems doable and more usefu...
by prao
04 Dec 2008 21:31
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

Would it be possible to attempt an kind of survivable soft landing for the CY mother ship at eom. May be spin up and use the LAM and attitude thrusters.....?? Thanks Interesting idea. Some points to consider: Currrently CY1 has 50% more fuel than it requires for the 2 yr mission so perhaps there wi...
by prao
04 Dec 2008 19:02
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

Good points all.
by prao
03 Dec 2008 20:38
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

Cutting edge An afterthought The MIP might have been an afterthought and may have been added because a person of Shri. Abdul Kalam's stature suggested it. It is also possible to claim that its inclusion compromised the mission's original objectives. But these arguments do not take into consideratio...
by prao
29 Nov 2008 02:34
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

SSSalvi wrote:
Thanks Rao for bringing out the woes of a design engineer. You said it!


:)
by prao
27 Nov 2008 02:10
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

hmm... how the orbital height has any significant effect on CY1's temperature ? Reports from ISRO indicated that reflected radiation from the Moon was one of the factors that caused the temperature rise. Apparently an increase in orbital height to reduce these effects was one of the options conside...
by prao
27 Nov 2008 00:33
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

8. The reality is that we built a more functional, utilitarian probe for much less than the Japanese. 9. The heat issue is not a major problem in that simple measures like not using the high voltage instruments continously + changing the orientation of the craft with respect to the sun while keepin...
by prao
26 Nov 2008 22:43
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

does this video match or better kayuga? Way better than Kayuga. Screw the HDTV. Screw too their crystal clear blue Earth and gray gray grayish lunar terrain, as if someone vomited Tejas' gray color scheme on a ship deck. ...deleted Why? Why be so jingoistic? Is there any purpose served? And just to...
by prao
26 Nov 2008 21:07
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 moon mission

It certainly does look like the camera has been turned sideways. I wonder if its a consequence of the 20 deg rotation performed recently. All available info indicates that the camera is normally to point straight down. The camera also has CCD's ahead and behind the central CCD that view the terrain ...
by prao
14 Nov 2008 21:13
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 mission launched succesfully

Woo hoo! :D Congrats ISRO! From this link posted above by SaiK: The 35-kilo payload crash-landed on the lunar surface at around 2030 hrs IST. The MIP has started sending its first signals to the satellite. and Closer to the surface, rockets were fired to slow down its speed and soften impact . This...
by prao
14 Nov 2008 20:35
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 mission launched succesfully

At least now I hope the events up to the landing (crashing?) of the MIP will be made clear. Main uestions in my mind: Was the MIP completely destroyed upon reaching the Lunar surface? Did any rocket fire anytime before touchdown to slow down the descent? Did it continue transmitting after touching t...
by prao
14 Nov 2008 20:11
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 mission launched succesfully

Wonderful wonderful achievement :D Congratulations ISRO! India and Indians the World Over are proud of you!
by prao
14 Nov 2008 05:54
Forum: Trash Can Archive
Topic: China Military Watch
Replies: 3944
Views: 928384

Re: China Military Watch

Chinese scientist calls for co-op between Asian space powers http://www.chinaview.cn 2008-11-12 21:06:43 Print BEIJING, Nov. 12 (Xinhua) -- A Chinese scientist on Wednesday called for moon probe program experts in China, India and Japan to step up cooperation to "deepen mankind's understanding...
by prao
14 Nov 2008 04:20
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 mission launched succesfully

The problem is that the Moon has a more complex motion than the Earth ( orbiting both Earth and Surya) FWIW - Don't know exactly what one means by "more complex motion" but both earth and moon orbit around the sun in a more or less an elliptical, orbit (with nearly same "e" and ...
by prao
14 Nov 2008 01:43
Forum: Mil-Tech Archive
Topic: Chandrayan-1 moon mission
Replies: 1807
Views: 291424

Re: Chandrayan-1 mission launched succesfully

There is a time delay integral tutorial for pushbroom imagers here that may be relevent to the TMC functioning.. In addition, with only a single pixel to collect photons for that very short amount of time, there's two serious limits on the sensitivity: dynamic range and signal-to-noise ratio of the...
by prao
14 Nov 2008 01:16
Forum: Trash Can Archive
Topic: Indian Space Program Discussion
Replies: 518
Views: 16157

Re: Indian Space Program Discussion

Indeed, plastic models of Indian rockets was what I was looking for when I came across the paper models. You'd think (hope?) that there might be some enterprising company that would try to leverage the pride among Indians to build and sell models of Indian rockets and satellites but I could find no...
by prao
14 Nov 2008 00:46
Forum: Trash Can Archive
Topic: Indian Space Program Discussion
Replies: 518
Views: 16157

Re: Indian Space Program Discussion

Came across this very interesting website of a Mexican gentleman who builds ingenious paper models. One of his paper models is India's very own GSLV! Indications are that a PSLV paper model is in the works too. Plans are posted. Here's the website: http://www.chihuahuadepapel.com/index.htm He is go...

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