Newbie Corner & Military Miscellaneous

negi · Post by **negi** » 17 Nov 2010 21:58

indranilroy wrote: We were speaking of just the shape of the antenna in the nose cone.

I have forgotten everything I studied in madrasa but shape of the antenna is critical to the beam form and side lobes which effect the directivity and gain of the antenna . I think folks still in touch with Antennas and wave propagation would be able to articulate it better.

Gurneesh · Post by **Gurneesh** » 20 Nov 2010 23:45

There seem to be some control surfaces on the leading edge of the Tejas wing like in this pic:

Could someone please explain what these are. Infact I have seen these i a number of planes but dunno the name and purpose.

Plus what maximum G turn has the tejas performed as of now (LSP 5 did 4G only).

nachiket · Post by **nachiket** » 21 Nov 2010 00:03

^^ They are Leading Edge Slats

Gaur · Post by **Gaur** » 21 Nov 2010 04:38

A newbie question regarding Kaveri.
Since we use polycrystalline blades in Kaveri, will it only limit the max thrust of Kaveri or will it also have an effect on its reliability? I ask this because of all the talk about integrating Kaveri in AMCA. Considering that Kaveri will need to face so much of erosive dust in Indian environment, will polycrystalline blades pose greater safety risk? Or will this have no significant effect?
Thanks.

Gurneesh · Post by **Gurneesh** » 21 Nov 2010 06:51

If I am not wrong then polycryst blades will pose problems at higher temperatures (where single cryst will work fine). As long as the designers are in the safe temperature limits, then there should not be any reliability problems. But that will come at a penalty of thrust.

Guru's, am I correct ?

Gaur · Post by **Gaur** » 21 Nov 2010 07:44

^^
To my limited understanding, anything that has grain boundaries will have less pressure tolerance than single crystal. If so, this would mean that Kaveri would have less MTBO than....lets say GE-404. But that is not a problem to me. Even if we have to replace Kaveri twice in AMCA, it would be infinitely better than replacing another imported engine once.

So, my question is not about service life but about reliability. My questions are as follows:

1> What are the main factors that result in faults within blades before their service life is over? By faults, I mean the ones which cannot be easily detected by ground service crew (eg: minor cracks perhaps, slight erosion, etc)...thus increasing the chance of accidents.

2> And will these factors be more of a problem for Kaveri? In short, will Kaveri be more accident prone than its counterparts with SCBs? Is service life directly proportional to reliability?

Gurneesh · Post by **Gurneesh** » 21 Nov 2010 09:59

A SCB will have uniform strength over it's entire body, which will be inherently more than a multi crys blade (MCB). This could be because in a MCB there are avenues of crack formation and propagation along the joint of the crystals. This means that for a MCB to work safely, the temperature and pressure (?) should be lower than a SCB engine. This would mean that an engine would have to operate at lower thrust to achieve same reliability as an engine with SCB.

For a MCB small cracks would be more dangerous though as if the crack happens to intersect with the crystal joint, it can easily propagate along that path and potentially rip the blade apart. These could be due to erosion by dust or fatigue (though unlikely as the blade should have a unidirectional stress). Also the stress encountered by the blade will be compressive. So if the blade is subjected to it's design stresses only then it could be as reliable as a SCB (barring external factors like dust), but it's service life may be lower.

On the other hand, IIRC Kaveri in the current state will not go into AMCA and DRDO will use the ECO core (which should have SCB i guess).

negi · Post by **negi** » 22 Nov 2010 09:20

--shaheedised by djinn; duplicate--

Indranil · Post by **Indranil** » 22 Nov 2010 09:22

Thank you Negi sahab.

narmad · Post by **narmad** » 23 Nov 2010 19:05

I have a noob pooch

With the advance in Design philosophy, do we still need the SAIL on a Submarine?

We do have tailless fighters now.

suryag · Post by **suryag** » 24 Nov 2010 07:48

Something that i have never been able to understand is why do we consider the tejas to be the third line of fighter after rambha, mmrca ? Atleast the specs of tejas measures up on par with that of the m2k, f16 or the gripen so why the sdre tejas third in the line.? tried searching for lca vs m2k and nothing good comes up when i asked google chacha

Austin · Post by **Austin** » 25 Nov 2010 12:23

A good friend came across this picture and shared it with me , We could see Mig-29 parked in icy condition in the open as well as couple of hangers around.

Do military fighter aircraft have de-icing capability something common in civil airlines that allows then to operate in dense ice cover conditions ?

shiv · Post by **shiv** » 25 Nov 2010 16:02

suryag wrote: why do we consider the tejas to be

Who is "we"?

Neela · Post by **Neela** » 25 Nov 2010 16:56

Gurus, I am reading a book in engine design and one of the first chapters is about air intakes.

1. The author mentions that the lips of commercial aircraft engines are thicker than those of military engines.
[ The silver part in the picture below]

The reason given is that in the static case, air is drawn from even behind the lips. This causes flow to separate because of extreme local acceleration inside the air-intakes near the lips ( Separated flow could damage the blades ). To prevent this, the lips are made thicker.
My question: how do they solve this flow separation in military engines?

2. This is something that I (possibly) realised after reading the book. In the same picture above, notice how the engine actually projects in front of the wing.? I think this is to avoid a distorted air-flow from entering the intakes...correct?. The book says that pylons, wings and fuselage all distort the flow. So I assume the the MD DC-10 would have had this distorted flow in the engine in the middle.
Also, I read that in the static case, vortices tend to form because of the ground below when the engine is idling. This problem vanishes when the aircraft is accelerating.

Eric Leiderman · Post by **Eric Leiderman** » 26 Nov 2010 09:13

Hi Everybody 1st Post.

What stops the indian navy fm building hulls / superstructures abroad maybe S.Korea or Japan and outfitting them in indian yards. The main expertise and therefore costs would be in the latter? This would be a stop gap measure till we have developed graving docks / slipways to handle the volume of newbuilds in the next decade.

aditya.agd · Post by **aditya.agd** » 27 Nov 2010 16:52

It seems that we did not capture all the territories back from Pakistan after the Kargil war. Why are we celebrating the Vijay Divas then... Can someone please confirm that we did not win territories back from Pakistan?

"The Indian army launched its final attacks in the last week of July; as soon as the Drass subsector had been cleared of Pakistani forces, the fighting ceased on July 26. The day has since been marked as Kargil Vijay Diwas (Kargil Victory Day) in India. By the end of the war, India had resumed control of all territory south and east of the Line of Control, as was established in July 1972 as per the Simla Agreement.

However it had failed to occupy strategic peak Point 5353, Bunker Ridge, Saddle Ridge and Dalu Nag.[60] Point 5353 is the highest peak in the region which has a clear view of the National Highway 1 D that connects the Kashmir valley with Kargil; it remains occupied by Pakistan even a decade after the battle.[61]"

http://en.wikipedia.org/wiki/Kargil_War

shiv · Post by **shiv** » 28 Nov 2010 06:54

aditya.agd wrote:It seems that we did not capture all the territories back from Pakistan after the Kargil war. Why are we celebrating the Vijay Divas then... Can someone please confirm that we did not win territories back from Pakistan?

"The Indian army launched its final attacks in the last week of July; as soon as the Drass subsector had been cleared of Pakistani forces, the fighting ceased on July 26. The day has since been marked as Kargil Vijay Diwas (Kargil Victory Day) in India. By the end of the war, India had resumed control of all territory south and east of the Line of Control, as was established in July 1972 as per the Simla Agreement.

However it had failed to occupy strategic peak Point 5353, Bunker Ridge, Saddle Ridge and Dalu Nag.[60] Point 5353 is the highest peak in the region which has a clear view of the National Highway 1 D that connects the Kashmir valley with Kargil; it remains occupied by Pakistan even a decade after the battle.[61]"

http://en.wikipedia.org/wiki/Kargil_War

The number 61 leads to the following link which has the explanation and the quote you have made above:

The Indian Army, which made several unsuccessful attempts to occupy the post after the Kargil war, has since given up the post as “untenable” given the geography of the region that makes it fairly easy for Pakistani troops to climb.

Why do we celebrate Vijay Diwas? Because we are morons and cowards who like to hoodwink others and pretend that great things were done in Kargil where a few dozen Mujahiddeen held back the entire Indian army until India went begging to the US to stop the war.

Jeff Wickline · Post by **Jeff Wickline** » 28 Nov 2010 12:15

Hi Everybody, Hi Gurus, my 1st Post.
Have been trying to figure out the advantages of thrust vectoring in fighter aircrafts. Most of the resources that search engines provided mention "post-stall maneuver". My newbie question is "Is post-stall maneuver a tactical necessity or for saving the aircraft in case of stall ?". Even a pointer to sub forums would be a great help. Thanks in advance

nachiket · Post by **nachiket** » 28 Nov 2010 12:18

profold wrote:Hi Everybody, Hi Gurus, my 1st Post.
Have been trying to figure out the advantages of thrust vectoring in fighter aircrafts. Most of the resources that search engines provided mention "post-stall maneuver". My newbie question is "Is post-stall maneuver a tactical necessity or for saving the aircraft in case of stall ?". Even a pointer to sub forums would be a great help. Thanks in advance

You can start with wikipedia: http://en.wikipedia.org/wiki/Supermaneu ... cteristics

Jeff Wickline · Post by **Jeff Wickline** » 28 Nov 2010 12:53

Thanks Nachiket. From the wikipedia page, you pointed out, I could (i) get a basic feel and (ii) download Ant Kutschera's Ph.D thesis (2000, Loughborough). On a first quick browsing the thesis appears to be a real gold mine. I am sharing this info for the benefit of newbies like me who would like to get a foundation on thrust vectoring.

Austin · Post by **Austin** » 28 Nov 2010 13:38

shiv wrote:Talking about LCA, elevons, stall and spin tests reminded me of my boyhood days and playing with planes. While I have resolved to buy material to start making models again - here is a time-pass video I have created entitled "Aerodynamics for dummies - a "crash" course"

Shiv that a simple yet nice video , now I know how to create a good rocket that can fly longer , faster ,further

Jeff Wickline · Post by **Jeff Wickline** » 28 Nov 2010 20:21

HAL produced a number of GT engines under license.
Can any of these (say the GNAT/Ajeet engine Orpheus 701-01?: 21kN, 823 mm dia, 442 kg weight ) be used for powering UAV's?
A newbie question onlee.

S_Prasad · Post by **S_Prasad** » 28 Nov 2010 21:51

http://3.bp.blogspot.com/_o_no4M2xEPY/T ... 764821.jpg
http://2.bp.blogspot.com/_o_no4M2xEPY/T ... 767299.jpg

Can someone explain me what the marcos are carrying slung acroos their belts that looks like a glove that we use to take food stuff out of micro oven's and what is it used for?

Rahul M · Post by **Rahul M** » 28 Nov 2010 22:26

^^^
http://forums.bharat-rakshak.com/viewto ... 75#p985175

abhinavjo · Post by **abhinavjo** » 02 Dec 2010 17:04

Greetings Everybody.
Can someone tell me what is the difference between AESA and PESA Radars. What all capabilities does an AESA equipped aircraft and ship have over a PESA equipped Aircraft/Ship

Gaur · Post by **Gaur** » 02 Dec 2010 18:26

^^
http://en.wikipedia.org/wiki/Active_Ele ... nned_Array

Bala Vignesh · Post by **Bala Vignesh** » 02 Dec 2010 22:00

Hi all,
Is there a thread or section here that has a list of must read stories (fiction & real) on military history and operations????
Thanks

suryag · Post by **suryag** » 02 Dec 2010 23:54

something that i have never been able to fathom is we can build nuke subs but not conventional diesel ones, is anything envisaged for a scaled down arihant running on diesel ?

VikB · Post by **VikB** » 03 Dec 2010 13:34

http://www.ndtv.com/video/player/news/f ... 996/147736

It shows the firing chamber so as to say. Plus the guy was on death sentence since 1985!!!! 25 years!!! in US!!!! and we call our system late.

sorry but didnt know where to put this

Bolasani · Post by **Bolasani** » 04 Dec 2010 20:10

I just saw an IAF dornier aircraft land at the Male International Airport, Maldives.

Could anybody please let me know what IAF aircraft do at Maldives.

PratikDas · Post by **PratikDas** » 04 Dec 2010 23:52

Could the gurus please suggest if it is a good idea to make an amphibian AEW&C platform out of the Beriev A-40?

http://www.beriev.com/eng/A-40_e/A-40_e.html

Pratyush · Post by **Pratyush** » 05 Dec 2010 09:50

Unless we understand the rational for the suggestion, it is difficult to comment regarding the suitability of the airframe for the intended use.

PS: it is a remarkable aircraft. Will be extreamly useful for pure maritime patrol and search and rescue operatons. If my vote counts. I say we get at least 20 of these for ASW and SAR duties.

like the ShinMaywa US-2

PratikDas · Post by **PratikDas** » 05 Dec 2010 11:08

Pratyush wrote:Unless we understand the rational for the suggestion, it is difficult to comment regarding the suitability of the airframe for the intended use.
---

IMHO an amphibious AEW&C platform would be more survivable for being able to move from land-base to naval-base, and from mainland to island. It would be able to pop up with an element of surprise and disappear easily. Just my thoughts.

Jeff Wickline · Post by **Jeff Wickline** » 05 Dec 2010 11:25

Re: Beriev A-40.
Thanks for drawing our attention to the above.
It is indeed a remarkable aircraft. The engines are also interesting.
But it appears that the sea based operation is only possible at relatively calm condition (<2m wave height). While it may be OK for large lakes and black sea, it would be doubtful whether it would be of much use in the Andaman and Lakshadwip.

SriSri · Post by **SriSri** » 05 Dec 2010 15:08

Hello BRfites,

I'm eager to learn about network centric warfare systems, communication systems, integration platforms presently in operation and planned for the future in the Indian Armed Forces.

Is there a DRDO wing that specializes in this?

- Sri

Jeff Wickline · Post by **Jeff Wickline** » 05 Dec 2010 16:24

^^ certainly you have visited the Wikipedia page of the same name. It has a good overview and many links. But these are about general aspects and not related to Indian Defense forces.
AFAIK there so far DRDO has not reported any initiative. (Would search again this forum though .) It would be up to the individual forces to define and implement, I guess.
Corrections: I got this in <<Post subject: Re: Indian Space Program Discussion>> by Shankar dated 09 Oct 2010>>
Quote:
"(DRDO), is developing a dedicated network-centric communication intelligence satellite for detecting conversations and espionage activities.
Unquote.
There are many posts related to network-centric operations in different threads.

SriSri · Post by **SriSri** » 05 Dec 2010 17:28

It would be up to the individual forces to define and implement, I guess.

Umm.. I hope not, integration mess! We already have the need to integrate many different Russian, European, American and Indian systems with each other.

kmkraoind · Post by **kmkraoind** » 06 Dec 2010 21:38

A newbie question

What are the propellants used in Nag and Akash missiles. The question is in the contest of new explosive ICL-20 developed by DRDO. I have heard that USN shown interest in CL-20 for air launched missiles. What will be range advantage, presumably if we use ICL-20 as propellants in Nag (especially air launched Helina version) and Akash missiles. TIA.

shiv · Post by **shiv** » 07 Dec 2010 08:33

kmkraoind wrote: What will be range advantage, presumably if we use ICL-20 as propellants in Nag (especially air launched Helina version) and Akash missiles. TIA.

That would be suicide.

Propellants are always slow burning compared to explosives and high explosives. Low Explosives burn up fully in a very short time. High explosives burn up in an even shorter time. Propellants need to burn relatively slowly and evenly to produce combustion products (gas) at a predictable and controlled rate. ICL 20 is high explosive. Diwali crackers are low explosive.

Using high explosive as propellant would cause the missile or gun barrel to explode. With explosive power metal is bent and twisted. With high explosives, metal is sheared and shredded.

negi · Post by **negi** » 07 Dec 2010 09:19

Shivji as per following CL-20's use as propellant is being researched .

http://www.drdo.gov.in/drdo/English/dpi ... _HEMRL.pdf

CL-20 a molecule that can be incorporated into both propellants and explosives

http://nopr.niscair.res.in/bitstream/12 ... 87-192.pdf