Indian Missiles and Munitions Discussion - June'14

[Rishi Verma]

I would think INS needs to be ON from ground. Simplistically, its synced on ground, it shows delta as it moves forward which allows the calculations to target.

what other "classified" inputs can there be to the INS platform.?? target coordinates?? way points?? or some sort of scene matching, area correlation thingee??

The INS is a fairly straight forward technology, a well understood and a reasonably matured system.

Classified as in radio frequency.. Or microwave...

About the "fairly straightforward", it's a great insult to engineers who make it. Have you ever made it? Try making a raspberry pie on your own first. I have noticed over the years that indian engineers read up the text book or wiki and decide its "straight forward"...

[chetak]

what other "classified" inputs can there be to the INS platform.?? target coordinates?? way points?? or some sort of scene matching, area correlation thingee??

The INS is a fairly straight forward technology, a well understood and a reasonably matured system.

Classified as in radio frequency.. Or microwave...

About the "fairly straightforward", it's a great insult to engineers who make it. Have you ever made it? Try making a raspberry pie on your own first. I have noticed over the years that indian engineers read up the text book or wiki and decide its "straight forward"...

I haven't "made" it but then neither have you.

I have worked with it for many years in real live applications for the military and foreign firms.

I have initialized it, installed it, removed it, done trouble shooting, repaired and tested it on very sophisticated automated test benches, flight tested it, analysed root causes along with the manufacturers and sometimes the designers.

All signals emanating from our missile and rocket launches are recorded by a great many countries, including the hans from their satellites and aircraft that track each and every single Indian launch.

So how is your radio signal "classified"??

or did you misread wiki and actually meant "encrypted"??

make raspberry pie??

alas actually no, but my wife and friends say that my apple pie is to die for.

[shiv]

Here is a good 5 minute aam abdul illustration of gyroscopic inertial guidance. I guess accelerometers are needed for sensing deviations of the mount from the original position
https://www.youtube.com/watch?v=ekzwbt3hu2k


I am no expert but I am sceptical of any claim that the inertial guidance needs update. The inertia cannot be changed, but the direction of movement of an aircraft/missile can be changed by suitable control inputs. But the actual direction will always be determined by the gyro and not by GPS - that is to sat that if the control input is - turn 30 deg East - the aircraft will turn until the gyro reading of direction says "It's now 30 deg east". That gyro - once started cannot be updated. it is stuck in the direction it was when it was started off. If someone has better information than this please post

[Rakesh]

make raspberry pie??

alas actually no, but my wife and friends say that my apple pie is to die for.

Pls check my BRF profile and kindly email your apple pie recipe. Thanks.

[shiv]

I think its porky pies that chetak dislikes. Apple pie is a good wholesome American thing

[Rakesh]

Nothing says America like apple pie!

[sudeepj]

The launch seq may be thus:
1. The TEL (which has its own INS/GPS or a presurveyed spot from which to launch) transfers the initial seed position to the missile. Also transfers the initial orientation.
2. The missile computer starts tracking both position and orientation after some built in senlf test, once everything looks ok, it would indicate to the launcher that missile is ok to fire.
3. Missile gets a kick in the pants to get moving.
4. The missile computer will sample at a very high rate, (few thousand Hz) the on board accelerometers and gyros. These measurements will be integrated over time (just added up) to determine the vehicle position and attitude.
5. Accumulated position errors will be corrected using some other mechanism, such as GPS waypoints.
6. I am not sure how accumulated orientation/attitude errors can be corrected..
7. If the INS says vehicle position is such that can not be handled/corrected by the missile computer, what should it do? For instance, if the INS says, vehicle is upside down, or in an attitude that is outside the design parameters, should the missile computer try to make it upright again? Even if its known that there is no way control inputs can be provided to put the missile in the reported attitude?

[JayS]

Here is a good 5 minute aam abdul illustration of gyroscopic inertial guidance. I guess accelerometers are needed for sensing deviations of the mount from the original position
https://www.youtube.com/watch?v=ekzwbt3hu2k


I am no expert but I am sceptical of any claim that the inertial guidance needs update. The inertia cannot be changed, but the direction of movement of an aircraft/missile can be changed by suitable control inputs. But the actual direction will always be determined by the gyro and not by GPS - that is to sat that if the control input is - turn 30 deg East - the aircraft will turn until the gyro reading of direction says "It's now 30 deg east". That gyro - once started cannot be updated. it is stuck in the direction it was when it was started off. If someone has better information than this please post

INS need three types of measurements: Linear Accelerations, Angular accelerations and angular position i.e. attitude. Reference location is known from the launch vehicle. So this is enough to calculate position in 3D space.

Though the rotating disc does not change its orientation the frames do and you pick up the angular position to see what is the current attitude. But to measure the angular acceleration we need to measure rate of change of angle of those frames. This is the one which could be the culprit. Too fast angular acceleration which cannot be picked up by sensor will send the control loop haywire.

Another thing is, we have Accelerometers to measure linear acceleration. They might get over-saturated and thus make INS useless.

PS: Found a good video about Ring LASER Gyro for noobs.
https://www.youtube.com/watch?v=xnN6vXIo_d0

[shiv]

Another thing is, we have Accelerometers to measure linear acceleration. They might get over-saturated and thus make INS useless.

Absolutely.

Question is - Is Brahmos inertially guided initially. The reason I ask is that its vertical launch is followed by a pretty hefty kick to tilt it vertical - in maybe 300-500 msec. That does not seem to upset the INS. But a sudden uncontrolled pitch/yaw/roll may throw it off tick

[JayS]

Another thing is, we have Accelerometers to measure linear acceleration. They might get over-saturated and thus make INS useless.

Absolutely.
https://www.youtube.com/watch?v=xnN6vXIo_d0
Question is - Is Brahmos inertially guided initially. The reason I ask is that its vertical launch is followed by a pretty hefty kick to tilt it vertical - in maybe 300-500 msec. That does not seem to upset the INS. But a sudden uncontrolled pitch/yaw/roll may throw it off tick

1. Precisely why I am also wondering about this whole loss of Ref. Frame business. To me Nirbhay could not have gone through any violent manoeuvre as such that would set INS off-track. The veering off must have been gradual anyway.

2. One possible explanation is the INS in brahmos is designed to handle higher accelerations than the one in Nirbhay. But in that case I would like to know why Nirbhay cannot have same INS that Brahmos has.

3. The original news posted a few pages back does say it was due to successive roll rate - high acceleration.

This malfunctioning of the mechanism that deploys the wing appears to have resulted in the missile developing a very high roll-rate, which led to the Inertial Navigation System (INS) losing its frame of reference. This caused the missile to veer away from its intended flight path,

[Indranil]

Chetak sir,

Are there known ways for the flight computer to identify garbage input from the sensors and enter a failure-recovery mode.

[chetak]

Here is a good 5 minute aam abdul illustration of gyroscopic inertial guidance. I guess accelerometers are needed for sensing deviations of the mount from the original position
https://www.youtube.com/watch?v=ekzwbt3hu2k


I am no expert but I am sceptical of any claim that the inertial guidance needs update. The inertia cannot be changed, but the direction of movement of an aircraft/missile can be changed by suitable control inputs. But the actual direction will always be determined by the gyro and not by GPS - that is to sat that if the control input is - turn 30 deg East - the aircraft will turn until the gyro reading of direction says "It's now 30 deg east". That gyro - once started cannot be updated. it is stuck in the direction it was when it was started off. If someone has better information than this please post

saar,

In a perfect world you would be right.

Aitcraft and ships also carry magnetic compasses, usually called "emergency compass" in aircrafts that the pilot by routine habit constantly compares one with the other to make sure that his gyro compass is OK. The gyro compass is subject to failure at times but the sturdy, simple and inaccurate emergency compass which has no mechanical or electrical or any other external input is almost always available to him. The gyro compass is totally dependent on very clean and accurate power supply, usually 115V, 3 Phase 400Hz supply or if ruskie, 26V, 3Phase, 400Hz if memory serves well. Add to this mechanical rotors rotating at extremely high RPM, bearings, electric motors, etc. All these can and do induce errors in one way or the other.

these inherent gyro errors are something that different manufacturers have tried to overcome using different designs. Errors may be reduced but not eliminated. It is these errors that cause the inertial platform to drift and such errors are "corrected" generally using the GPS to "update" the INS data which again has it's own errors due to the purposely introduced jitter that corrupts the commercial GPS signals. To all this add accelerometer errors, sensor errors etc

This jitter is removed in the military GPS reciever (but not in the commercial GPS receivers) which gives it an inherently increased accuracy for precision bombing, targeting, navigation and whatnot.

Companies like Sperry in the UK and Anschutz in Germany are pioneers in gyro systems and a look at their designs would be illuminating.

Ring laser gyros are very much more accurate in comparison but still drift a bit and cumulative errors still affect the inertial platform accuracy.

Commercial INS, normally fitted on commercial aircraft and ships and military use INS in countries like ours have access only to the commercial GPS signals which the amrekis can turn off and on at will by using a technique of shading the GPS antenna as the satellite "rises" over a specific geographic area.

This is how we got maroed in kargil when the silly amreki buggers tried to disrupt the precision bombing runs of the IAF by denying us the GPS signals over cashmere thereby making the jobs of the IAF pilots that very much more difficult.

many other uncounted sly shenanigans like this is why the untrustworthy amrekis remain very unpopular with the Indian forces.

This is also why the hans and India and europe have now got their own SATNAV systems. The ruskies have had GLONAS for the longest time to protect themselves. There are easily available GPS/GLONAS dual system receivers in widespread use.

[Neshant]

Commercial INS, normally fitted on commercial aircraft and ships and military use INS in countries like ours have access only to the commercial GPS signals which the amrekis can turn off and on at will by using a technique of shading the GPS antenna as the satellite "rises" over a specific geographic area.

This is how we got maroed in kargil when the silly amreki buggers tried to disrupt the precision bombing runs of the IAF by denying us the GPS signals over cashmere thereby making the jobs of the IAF pilots that very much more difficult.

many other uncounted sly shenanigans like this is why the untrustworthy amrekis remain very unpopular with the Indian forces.

This is also why the hans and India and europe have now got their own SATNAV systems. The ruskies have had GLONAS for the longest time to protect themselves. There are easily available GPS/GLONAS dual system receivers in widespread use.

How is India buying howitzers from the US for Ca$hmire if their operation depend on GPS?

[chetak]

Chetak sir,

Are there known ways for the flight computer to identify garbage input from the sensors and enter a failure-recovery mode.

No need for sir, saar

I use saar as a Bangalore/KAR form of address by sheer force of habit.

Usually, valuable platforms (meaning legally liable!!) like commercial ships, commercial aircraft and also many MIL aircraft etc have multiple channels in the FCS/Auto Pilot system. Each channel is independent and separate and also unique in terms of hardware, software, build specs, software language etc to ensure that inherent failure mechanisms in one systems/channel are not duplicated in the other system/channel thereby causing loss of the asset.

This is to guard against common cause failures. Risk analysis for common cause failures is very complex and mistakes are easily made as was painfully realized by the poor japanese after the fukushima disaster.

To address your question, the inputs from multiple systems/channels are compared in real time by a "voting system" or "polling" whereby sensor data from different channels are compared and passed only if they lie within predetermined limits. Any data outside of the set limits are declared as "garbage" and ignored. A majority of channels have to agree if the data is to be accepted as good and passed on for further processing. if a majority of the channels do not agree, then the data is not used.

In Airbus, which has a 4 channel FCS, three out of four systems have to agree before the data is declared as"good". Boeing also has a similar system.

A continuously arriving stream of data is good enough for system stability even if some "corrupted or ignored" data is dropped due to some momentarily present glitch in the sensor(s).

If the sensor(s) is kaput for any reason, depending on the importance of the sensor(s), the flight control law in use will/may automatically degrade to an alternate law with reduced functionality and there are loud audio visual warnings to alert the crew.

Failure protection is simply to ensure that the aircraft remains within the design flight envelope.

If an over speed condition is detected, the engines will be automatically commanded to reduce thrust to maintain the speed within the flight envelope.

If a Boeing / Airbus aircraft enters a stall, the sticks shakes violently and the nose is commanded to pitch down to recover from the stall.

Remaining within the flight envelope ensures that the aircraft does not exceed airframe design loads and other limits at all times appropriate to the flight regime that the aircraft is operating in.

[chetak]

Commercial INS, normally fitted on commercial aircraft and ships and military use INS in countries like ours have access only to the commercial GPS signals which the amrekis can turn off and on at will by using a technique of shading the GPS antenna as the satellite "rises" over a specific geographic area.

This is how we got maroed in kargil when the silly amreki buggers tried to disrupt the precision bombing runs of the IAF by denying us the GPS signals over cashmere thereby making the jobs of the IAF pilots that very much more difficult.

many other uncounted sly shenanigans like this is why the untrustworthy amrekis remain very unpopular with the Indian forces.

This is also why the hans and India and europe have now got their own SATNAV systems. The ruskies have had GLONAS for the longest time to protect themselves. There are easily available GPS/GLONAS dual system receivers in widespread use.

How is India buying howitzers from the US for Ca$hmire if their operation depend on GPS?

No idea, saar.

Past bad behavior should have taught us a lesson.

We are still paying back for the Nuke deal where we could not give the nuke reactor projects to the US as expected by them??

[chetak]

Nothing says America like apple pie!

Never worked for any amreki firm so far. Have one tentative offer though.

Apple pie is courtesy of my canadian relatives who have become upset with the unusable and large production of apples from their trees in a neighborhood filled with houses which also have apple trees.

[tsarkar]

I'm a bit curious why we're discussing INS in the first place.

If I set my mobile map a route from Bombay to Delhi and then start driving to Bangalore, how can the mobile correct the car direction unless the driver does? The mobile doesn't control the steering, the driver does.

The INS is used for long range navigation whereas the missile flight is controlled by the flight computer. If the missile is rolling & tumbling, it's for the flight control computer to correct.

If the missile did acquire stable flight - which in my reading of the situation it didn't - then only whether INS functioned or not can be examined.

INS can take jolts - like the TVC moving it from vertical to horizontal in case of Klub / BrahMos / Nirbhay. However, the missile needs to be flying properly for the INS to navigate and INS does not control the flight control surfaces.

Possibly accelerometer inputs from INS are used by Flight Control Controller along with altimeter inputs, but that would be it.

If a car is falling in a khud on its way from Bombay to Delhi, the mobile map won't stop or correct the fall.

This malfunctioning of the mechanism that deploys the wing appears to have resulted in the missile developing a very high roll-rate, which led to the Inertial Navigation System (INS) losing its frame of reference. This caused the missile to veer away from its intended flight path,

In my humble opinion, the missile was out of control, and there is nothing the INS could do to stop the rolling or keep it in any kind of flight path.

The missile veering was due to rolling. INS losing reference was a consequence and not a cause.

[ramana]

It's slow week.
Root cause is the out of tolerance support bushing which caused partial wing deployment leading to missile roll which caused the INS to lose frame of reference.
Wonder how many vehicles were assigned for flight testing? And when is the next test?

BTW any updates on Astra low level intercepts?

[Cybaru]

Classified as in radio frequency.. Or microwave...

About the "fairly straightforward", it's a great insult to engineers who make it. Have you ever made it? Try making a raspberry pie on your own first. I have noticed over the years that indian engineers read up the text book or wiki and decide its "straight forward"...

I haven't "made" it but then neither have you.

I have worked with it for many years in real live applications for the military and foreign firms.

I have initialized it, installed it, removed it, done trouble shooting, repaired and tested it on very sophisticated automated test benches, flight tested it, analysed root causes along with the manufacturers and sometimes the designers.

All signals emanating from our missile and rocket launches are recorded by a great many countries, including the hans from their satellites and aircraft that track each and every single Indian launch.

So how is your radio signal "classified"??

or did you misread wiki and actually meant "encrypted"??

make raspberry pie??

alas actually no, but my wife and friends say that my apple pie is to die for.

Good one!! Bring it to Jigra next time!

[jamwal]

Apogee Data
http://www.astronautix.com/i/india.html

https://books.google.co.in/books?id=Yt2 ... ni&f=false

According to DRDO , the payload of Agni 3 is only 1500kg .

Thanks for pointing out the error. I haven't had the time to work on this since I posted this image.

[Rakesh]

MTCR Membership brought enormous benefits to India
http://www.defencenews.in/article.aspx?id=249929

[ramana]

MTCR Membership brought enormous benefits to India
http://www.defencenews.in/article.aspx?id=249929

Defence News article is a bogus one. It claims India Russia cooperation on Brahmos is a result of Mtcr which is laughable.
Brahmos II was in the works regardless.
More important is sale of missile related hardware from West.
So far zilch except talk of Javelin anti tank missiles!!!!!

[John]

It talks about Brahmos range extension which came after MTCR not about Brahmos 2.

[Indranil]

There is more reason to cheer for this Pinaka Mk2 success. India is slowly moving over to NEPE-based propellants. Nirbhay-booster and Pinaka Mk2 are the first to use them. Click here. This will make our missiles lighter and reach further.

Also gleaned from that link, the SFDR-based A2A missile will have a range of 120 km in power on mode.

[Cybaru]

Akash is a solid ramjet engine right? Would this be useful there?

[Indranil]

You mean NEPE-propellant? May be to the booster, but not the sustainer. I remember seeing a tender from DRDL for a test stand of LFRJ engine. the dimensions were identical to Akash. But a liquid fueled S2A missile in today's world. Let's see.

P.S. I think Akash won't see much more development past the Mk2 version. We are likely to see Astra-based weapons as our next gen QRSAM/SRSAMs.

[Rakesh]

India to pitch for defence exports of indigenous missile systems
http://economictimes.indiatimes.com/art ... 602193.cms

[Rakesh]

Dr G Satheesh Reddy, DG Missiles with Manohar Parrikar at the integration centre in RCI Hyderabad today...
https://twitter.com/writetake/status/820974630794096640

[ramana]

Dr G Satheesh Reddy, DG Missiles with Manohar Parrikar at the integration centre in RCI Hyderabad today...
https://twitter.com/writetake/status/820974630794096640

Interesting hardware: small graphite nose cones and a seeker on the table. Interesting people too.

[Philip]

Was this posted earlier? If so apols. Peculiar,as we've had tests of so many other missile types whose failures during testing if at all,have not been attributed to this fault.

http://www.defenseworld.net/news/18221/ ... H4R8NJ96M8

Wing Deployment Delay caused Nirbhay Missile’s Third Failure: DRDO
Our Bureau12:25 PM, January 14,

Wing Deployment Delay caused Nirbhay Missile’s Third Failure: DRDO Wing Deployment Delay caused Nirbhay Missile’s Third Failure: DRDO - A +
Delay in the process of wing deployment has led to third failure of India's Nirbhay subsonic cruise missile, according to Defense Research and Development Organisation (DRDO).
The failed mission of subsonic cruise missile Nirbhay was pointing towards a slight ‘pause’ during the wing deploying process, resulting in the missile developing a very high roll-rate, which led to the Inertial Navigation System (INS) losing its frame of reference, Mathrubhumi reported Friday.
This, further, caused the missile to move away from its intended flight path, leading to a situation which called for aborting the mission from safety considerations.
The Defense Research and Development Organisation (DRDO), who reviewed the video footage of the missile’s failed flight, confirmed that the wing is normally deployed in less than 500 milliseconds (0.5 sec.) after booster burn-out and separation of the booster section from the main missile.
In the previous missions, we have been achieving the wing deployment in around 300-350 milli-seconds. This time the wing seems to have got stuck at 60 degrees position for about 1.5 seconds causing the damage, the official said.
"This is what we have assessed so far. The missile appears to have developed the high roll rate due to the partially deployed wing”, the official added.


During the vertical launch of the missile, the booster fires for about 10 seconds, resulting in the missile gaining height and acceleration. It is in this phase that the Thrust Vector Control (TVC) system rotates the missile from vertical to horizontal attitude.
On burn-out of the booster, the booster section is detached from the main missile by activation of pyro-bolts and small thrusters ensure that the detached section separates safely from the main missile.

[ramana]

Wing deployment in 300-350 millisec and500 millisec is max allowed.

So taking 300- 500 as the range
400 +/- 100 millisec. Assuming normal distribution then sigma is 100/3 about 33 millisecs 0r 0.033 secs

Current test the wing deployed in 1.5 secs
Which is 1.5/(0.033)) = 45 sigma. Totally out of family.

[negi]

Nirbhaya is the only one with most moving parts , wing and even the motor so a longer testing phase should be expected .

[John]

Nirbhaya is the only one with most moving parts , wing and even the motor so a longer testing phase should be expected .

Brahmos and Barak 8 are more expensive and equally complex missile systems but had much shorter and more intensive testing cycle. All signs of mismanagement and throwing way to many features into first variant.

[Rakesh]

Why our Agni V launch fired up China
http://www.thehindubusinessline.com/opi ... 474120.ece

CHINA FRETS AND FUMES: THE LATEST AGNI V TEST HAS NOT GONE DOWN WELL WITH THE NEIGHBOR
https://www.theindianpanorama.news/indi ... H-lDlMrKM8

[Supratik]

I will add one more factor to the difference between 2012 and 2016. India has overtaken China in growth rate. This year may be the second in a row despite demo. Projections for the next two years are the same. First boy is no longer first and may not be in the near future as Chinese growth slows towards a lower trajectory (economic growth from developing to developed is a bell-shaped curve). It means competition may be catching up. The missile is the same unless they tested MIRVs.

[kurup]

New NAVAREA Warnings

INDIA EAST COAST – OFF BALASORE (.) CHARTS 31 351 352 3031 INT 71 (.)

EXPERIMENTAL FLIGHT TRIAL SCHEDULED FROM ITR ON 24, 25 AND 27 JAN 17 FROM 0530- 0930 UTC IN DANGER ZONE BOUNDED BY

21-22.36N 086-55.59E, 21-13.92N 086-51.84E, 20- 39.66N 087-22.32E, 20-52.38N 087-36.66E, 21-25.74N 087-05.16E, 21-22.88N 086-56.20E

2. CANCEL THIS MSG 271030 UTC JAN 17

[ramana]

What does it look like? Picture blocked.

[soumik]

seesm to be a NOTAM for another PINAKA trial!

[Cybaru]

85 kms NOTAM for 65KMS test! Nice!

[Singha]

Could it not be a ground launch of astra2