LCA: News & Discussions - October 2016

Gyan · Post by **Gyan** » 24 Mar 2017 09:30

Let's see if team ADA And HAL are able to produce 11 LCA in this financial year ie almost one LCA per month.

Dileep · Post by **Dileep** » 24 Mar 2017 13:00

FOC won't happen for another year as I see it. March 2018 is my bet.

Depressing... I know....

JayS · Post by **JayS** » 24 Mar 2017 15:05

Dileep wrote:FOC won't happen for another year as I see it. March 2018 is my bet.

Depressing... I know....

What..? Whats new roadblock now..?

NRao · Post by **NRao** » 24 Mar 2017 18:21

Dileep wrote:FOC won't happen for another year as I see it. March 2018 is my bet.

Depressing... I know....

1) Any reason/s - that you are aware of or educated guesses on your part?

2) What is your (or anyone elses) feeling on impact on Mk1A?

3) Would the MK1A need to go through IOC/FOC thread too or is the IOCFOC for MK1 sufficient?

JayS · Post by **JayS** » 24 Mar 2017 18:55

NRao wrote:
3) Would the MK1A need to go through IOC/FOC thread too or is the IOCFOC for MK1 sufficient?

Even Jaguar upgrade is going through the same cycle I think. So I think technically MK1A also will go through this cycle. Only thing is it may be easier to run through it relatively speaking, with less milestones to cover. If there is no serious change in LCA's configuration (like 800kg reduction) then perhaps it may not need IOC separately. It again depends on CEMILAC and how well ADA/HAL can convenience CEMILAC.

NRao · Post by **NRao** » 24 Mar 2017 21:07

JayS wrote:
NRao wrote:
3) Would the MK1A need to go through IOC/FOC thread too or is the IOCFOC for MK1 sufficient?
Even Jaguar upgrade is going through the same cycle I think. So I think technically MK1A also will go through this cycle. Only thing is it may be easier to run through it relatively speaking, with less milestones to cover. If there is no serious change in LCA's configuration (like 800kg reduction) then perhaps it may not need IOC separately. It again depends on CEMILAC and how well ADA/HAL can convenience CEMILAC.

The focal diff between the two is the radar. Do not see a way around major IOC/FOC work for that. ????

Indranil · Post by **Indranil** » 24 Mar 2017 21:43

Gyan wrote:Let's see if team ADA And HAL are able to produce 11 LCA in this financial year ie almost one LCA per month.

That was never the target. Why set up for failure?

JayS · Post by **JayS** » 24 Mar 2017 23:23

Gyan wrote:Let's see if team ADA And HAL are able to produce 11 LCA in this financial year ie almost one LCA per month.

FYI

https://twitter.com/writetake/status/827122637327314944

Here's #Tejas SP schedule at HAL for all those pinged me today, post my piece. 16-17: 5; 17-18: 8, 18-19: 12, 19-20: 16. In pic SP5.

JayS · Post by **JayS** » 24 Mar 2017 23:31

NRao wrote:
JayS wrote:
Even Jaguar upgrade is going through the same cycle I think. So I think technically MK1A also will go through this cycle. Only thing is it may be easier to run through it relatively speaking, with less milestones to cover. If there is no serious change in LCA's configuration (like 800kg reduction) then perhaps it may not need IOC separately. It again depends on CEMILAC and how well ADA/HAL can convenience CEMILAC.
The focal diff between the two is the radar. Do not see a way around major IOC/FOC work for that. ????

Radar doesn't change flying characteristics, thus no particular need for IOC, thats what I am thinking.

Viv S · Post by **Viv S** » 24 Mar 2017 23:35

JayS wrote:https://twitter.com/writetake/status/827122637327314944

Here's #Tejas SP schedule at HAL for all those pinged me today, post my piece. 16-17: 5; 17-18: 8, 18-19: 12, 19-20: 16. In pic SP5.

SP-5 to fly next month?

Marten · Post by **Marten** » 25 Mar 2017 01:06

Dileep wrote:FOC won't happen for another year as I see it. March 2018 is my bet.

Depressing... I know....

Are they trying to accommodate further RFAs from MK1A?
I mean has the SOP been updated again, Sir?

Indranil · Post by **Indranil** » 25 Mar 2017 01:43

JayS wrote:
NRao wrote:
The focal diff between the two is the radar. Do not see a way around major IOC/FOC work for that. ????
Radar doesn't change flying characteristics, thus no particular need for IOC, thats what I am thinking.

The plan seems to have evolved from no LSPs for Mk1A to modifying an Mk1 LSP to an Mk1A LSP. I don't think that any of the components will need re-certification to fly.But they are going to move some of the LRUs around for better manufacturing and maintenance. This would not require any major structural changes or effect any significant movement in the CG, but some brackets and supports may change. So, a mini-IOC (all elements certified to fly safely) may be required. However, they might combine it with the FOC which would be mainly centered around the radar+A2A weapons, and RWR and jamming pod. That should not take more than an year of flight testing. But, let's see.

srai · Post by **srai** » 25 Mar 2017 03:54

Radar customization work might delay things. A new radar tender was floated by HAL a few months ago and supposed to be selected next month.

Dileep · Post by **Dileep** » 25 Mar 2017 08:14

FOC will happen only when all requirements are satisfied. Radar is nowhere close. Gun is yet to fly. Missiles need a lot of work. It takes time. Nothing new is coming. Only existing ones are there.

There are a lot of "typical indian problems" in the whole setup.

It doesn't really matter, since planes are getting built, induction is happening, and IAF is flying them.

Dileep · Post by **Dileep** » 25 Mar 2017 08:22

What is Mk1A? It is a backport of MK2 avionics into MK1. Simple onlee. There will be no change in the flying side, so no IOC required.

Visibly, it will have a different cockpit layout with more glass and less plastic/metal. Behind the panels, you will see less number of boxes and thinner and 'lighter' cable looms. It will fly the same and fight the same.

Singha · Post by **Singha** » 25 Mar 2017 08:51

why is the gun so lagging behind? was it a case of deeply underestimating the vibration effect of the powerful gun on what is a very light airframe?

what is the radar for the Mk1A ? I thought it was going to be same EL2032 ?

shiv · Post by **shiv** » 25 Mar 2017 09:03

Singha wrote:why is the gun so lagging behind? was it a case of deeply underestimating the vibration effect of the powerful gun on what is a very light airframe?

what is the radar for the Mk1A ? I thought it was going to be same EL2032 ?

I think we keep on underestimating the ability of Indian engineers to think. Most likely the gun is left to the last because if the gun does untold vibration damage to other systems early in the program - the entire program gets held up. Once everything else is proven and ready the gun carriage and firing trials can begin on one dedicated and suitably telemetered aircraft to set limits on how long the gun can be fired (in bursts) without doing damage or whether the entire 150 rounds or so can be fired off in a 2.5 second burst. As we all know gun trials have already taken place on the ground.

Indranil · Post by **Indranil** » 25 Mar 2017 10:02

No Hakeem. The gun testing should not have been left to the end. Thankfully, the gun and the structures are all fine

shiv · Post by **shiv** » 25 Mar 2017 10:33

Indranil wrote:No Hakeem. The gun testing should not have been left to the end. Thankfully, the gun and the structures are all fine

The HF 24 experience showed how the gun firing tests virtually crippled the program by causing completely unexpected problems. Eventually the HF 24 never went beyond clearance for firing 2 guns and that was in an era when the only noteworthy electronic items on board were rudimentary compared to today. On the Tejas, in due course, when a new radar is fitted - those gun trials will have to be done yet again to make sure that the vibration is not throwing everything off gear - so an early clearance of the gun will mean little if it all has to be repeated with every new avionic gizmo added.

Among problems that have been recounted from gun firing tests are canopy flying off when the gun was fired and gunsight coming loose and falling out (may have been HUD?), loss of control and engine choke up from muzzle gas ingestion, and even crashes. Going into service first without a gun initially is not uncommon - and includes worthies like the F-35 and Eurofighter

JayS · Post by **JayS** » 25 Mar 2017 12:15

Singha wrote:why is the gun so lagging behind? was it a case of deeply underestimating the vibration effect of the powerful gun on what is a very light airframe?

what is the radar for the Mk1A ? I thought it was going to be same EL2032 ?

My opinion alwas has been that they have done enough preliminary testings including ground firing to give them confidence that the gun mounting structure is strong enough to absorb all the shocks and vibrations and will not pass it on to the LRUs. They always seem very casual and confident about it.

Mk1A was to have 2052, but with this new tender it will be the one which wins the tender.

BTW Tejas LCA FB page admin said we should have a good news on Gun trials soon.

JayS · Post by **JayS** » 25 Mar 2017 12:26

Dileep wrote:FOC will happen only when all requirements are satisfied. Radar is nowhere close. Gun is yet to fly. Missiles need a lot of work. It takes time. Nothing new is coming. Only existing ones are there.

There are a lot of "typical indian problems" in the whole setup.

It doesn't really matter, since planes are getting built, induction is happening, and IAF is flying them.

It doesnt matter if they can freeze (or already have frozen) the FOC SOP in time so manufacturing can start without any issues.

ramana · Post by **ramana** » 25 Mar 2017 12:43

HF-24 had 4 Aden 30 mm revolver cannon which had high recoil. The Hawker Hunter also had the same 4 gun capability and we never heard of the problems that HF-24 had. Most likely the gun mounting locations were not properly chosen to absorb the recoil.
On the other hand Tejas has the twin barrel GSh 23 auto cannon which has less recoil and the mounting location is the fuselage.
A year ago we saw the groupings from ground trials which were pretty good. This test would have proofed the gun capability, the LRUs for shock and vibration. Remaining is flight test integration.
I don't know where engine intake is but line diagram should show that.
Also the LRUs are being reduced in number and relocated in some instances.
Generally avionics packages are qualified for envelope shock and vibration levels which are 3 sigma levels over normal loads. This is std aviation design practice.

In other words don't worry.

Will talk about missiles.
Tejas can fire short range Infra red missiles.
It should fire Derby with Elta 2052 radar.
Eventually Astra with Uttam.

Neela · Post by **Neela** » 25 Mar 2017 14:40

Havent we already installed Nexter-Giat guns on the HAL Dhruv and also on the LCH. Vibration dampening and isolation has been studied and installed there. Its not something new then no?

Bala Vignesh · Post by **Bala Vignesh** » 25 Mar 2017 15:33

LCA uses Gsh23-2, not the Nexter 20mm one installed in LACY..

Dileep · Post by **Dileep** » 25 Mar 2017 21:09

Ramana, the 'horse race' will happen in April, as I overhear. So, no need to wait till the 2052 it seems.

Gun Vibrations are part of the test requirements of at least some LRUs now. So is lightning. How to design in compliance is the question.

For those who can figure, the typical spec for ESD is 8KV Air/4KV Contact. We have done a handheld device to 30KV air/15KV contact. Not sure what it takes for lightning!!

shiv · Post by **shiv** » 25 Mar 2017 21:53

Gun vibration is a fascinating problem and while I don't know how engineers and designers might handle it - I do know that "vibration" is a massive issue in several high tech sectors - stating from Uranium centrifuges to Apache mast radars and, of course guns.

OFB site says each projectile is 174 grams and is shot off at 720 m/sec at the rate of 50 plus rounds per second. That is a lot of kilojoules of energy which has to be transmitted to the airframe. Insulating every bit of the plane from such vibration can't be trivial

ramana · Post by **ramana** » 25 Mar 2017 22:57

Vibration is misnomer. It's repeated shock from the gun usage. However the shock gets translated to vibration as the package responds from its own natural frequency. So usually the gun is shock mounted to isolate and sensitive packages are also shock mounted. There is dichotomy between shock and vibration mounts.Shock mount limit travel and have to be stiff while vibe mounts are softer and change the pkg frequencyresponse.

All this from Shock and Vibration handbook only.

shiv · Post by **shiv** » 26 Mar 2017 06:37

ramana wrote:Vibration is misnomer. It's repeated shock from the gun usage. However the shock gets translated to vibration as the package responds from its own natural frequency. So usually the gun is shock mounted to isolate and sensitive packages are also shock mounted. There is dichotomy between shock and vibration mounts.Shock mount limit travel and have to be stiff while vibe mounts are softer and change the pkg frequencyresponse.

All this from Shock and Vibration handbook only.

Ah thanks. I would not have guessed this differentiation - i.e. shock on the one hand versus vibration in native harmonic

OT but the place where I have personal experience of this is in spring powered air rifles ("springers") which set off a deadly "dual shock" when shot which is worse than that of a 0.22 rifle which is vastly more powerful. The spring moves a plunger that causes a standard recoil but microseconds later the plunger hits the end of its chamber and causes a shock that opposes the initial recoil. This sets up some crazy vibration in the spring and barrel which is lethal to some of the most expensive rifle mounted telescopes unless they are certified for springers. I have myself killed a telescope before I found out about this. Springer owners must confirm this before investing in telescopes that could cost as much as the rifle in India

I had made a short (48 sec) video of springer barrel vibration

sorry OT

Indranil · Post by **Indranil** » 26 Mar 2017 10:25

Hakeem, the reason the gun should be tested first is that you finalize the structure first. If the structure tests good and you will also know the nature of the shocks passed to each LRU mount. Each LRU Every component that goes on afterwards is unit tested for those shocks levels, periodicity, durations etc.

If the gun did create a problem a now, they would have to change the structure which is is a do-over. Thankfully, the gun and the structures are doing just fine. The level of shocks experienced on ground in a static test is actually higher than that felt in the air. The gun is not supposed to create any problem. Nobody in ADA is worried about it.

They have all tests planned out in order. Which test on which LSP etc. They are finishing off test by test. Unfortunately, they had not factored in Aero-India and Republic Day earlier. These have delayed the process a bit. But FOC is an eventuality. Stabilizing the production to 16 airplanes per year is the job at hand.

shiv · Post by **shiv** » 26 Mar 2017 10:47

Indranil wrote:Hakeem, the reason the gun should be tested first is that you finalize the structure first.

Absolutely no disagreement with this. I am only disputing the idea suggested that some tests left to the end indicate that they never thought about the gun first. As I have been saying repeatedly, some on board equipment (LRUs) may need to be qualified to work along with gun firing. So even if the structure has been designed properly, gun tests may well be required again and again towards the end. It would be an error to fit on a new avionic item (or even a light or cockpit panel) and then discover that its mounting cannot shield it from the vibration inevitable from gun firing.

Dileep · Post by **Dileep** » 26 Mar 2017 12:22

The continuous firing of Gsh will cause a 50-60Hz vibration with a very strong second harmonic at 100-120Hz. A single shot will cause a shock. Continuous firing at a constant rate will cause vibration onlee.

Zynda · Post by **Zynda** » 26 Mar 2017 12:39

^^What is the significance of the second harmonic? Will it affect the airframe, LRUs and/or LRU mountings in any way?

Dileep · Post by **Dileep** » 26 Mar 2017 12:56

^^No special significance. If you know how the vibrations look like, it is easier to design against it no?

When the spec is not available, we tend to use the imagination onlee.

shiv · Post by **shiv** » 26 Mar 2017 15:01

FYI
We actually used this aircraft..
https://en.wikipedia.org/wiki/Gryazev-Shipunov_GSh-6-30

On the Mikoyan MiG-27 the GSh-6-30 had to be mounted obliquely to absorb recoil. The gun was noted for its high (often uncomfortable) vibration and extreme noise. The airframe vibration led to fatigue cracks in fuel tanks, numerous radio and avionics failures, the necessity of using runways with floodlights for night flights (as the landing lights would often be destroyed), tearing or jamming of the forward landing gear doors (leading to at least three crash landings), cracking of the reflector gunsight, an accidental jettisoning of the cockpit canopy and at least one case of the instrument panel falling off in flight. The weapons also dealt extensive collateral damage, as the sheer numbers of fragments from detonating shells was sufficient to damage aircraft flying within a 200-meter radius from the impact center, including the aircraft firing.

HF 24 Marut
http://www.bharat-rakshak.com/IAF/Histo ... dents.html

During several tests of firing two-second long four gun firing, no trouble was encountered. Then it was decided to do a four-second or maybe longer burst. Saper volunteered to do this, though it was not demonstrated by HAL, at least on that aircraft. Over Sarmath Range during gun firing, the pawl engaging the aileron linkage came out and caused a sudden bank, probably to the right. Those who had encountered this problem after practice manual flying might know that re-engaging hydraulic power often caused a sudden and high roll to one side. The natural tendency was to fight the roll, but the way to engage it was to roll into the roll. This was obviously not possible for Saper, even if he knew of it. The aircraft went into the Gulf of Kutch and was never found again.

F-100 Super Sabre
https://books.google.co.in/books?id=oEI ... on&f=false

IFF failure due to vibration from 4 gun firing

srai · Post by **srai** » 26 Mar 2017 18:05

Very detailed reports on the LCA 2013-15, including what each airframe was used for and how many flights and hours was accumulated. Also has information on AMCA and Ghatak UCAV. Full financial disclosure is also there as to the budget and which companies/institutions got paid how much for what.

ADA - 29th Annual Report 2013-2014

ADA - 30th Annual Report 2014-2015

Anyone can find the latest report?

fanne · Post by **fanne** » 26 Mar 2017 21:49

Per the reports linked above, Gun testing has been going for a long time with satisfactory result.

Rishi Verma · Post by **Rishi Verma** » 26 Mar 2017 23:31

Dileep wrote:The continuous firing of Gsh will cause a 50-60Hz vibration with a very strong second harmonic at 100-120Hz. A single shot will cause a shock. Continuous firing at a constant rate will cause vibration onlee.

The tiny para above have too many factually incorrect statements, terminology etc. If discussing engineering it's important to use the right terminology and not throw in terms like "2nd harmonic" besides I think you are mistaking resonance with vibrations.

Anyway, coming back to LCA gun firing:

Vibrations can be dampened by a number of different methods. Vibrations often occur in an aircraft and decay out, but if it's resonating with the cause then only it's dangerous.

Gun-caused vibrations should be easy thing for LCA engineers to resolve.

http://www.sorbothane.com/vibration-dam ... erial.aspx

Lalmohan · Post by **Lalmohan** » 26 Mar 2017 23:56

isn't the bigger issue in aircraft that there isn't enough structural mass to actually act as a damper?

Eric Leiderman · Post by **Eric Leiderman** » 27 Mar 2017 04:37

Dampening to a large extent depends on mounting. the weight of the source which is causing the issue, to control the recoil the amplitude of the force to be dampened. Taking a wild guess below. the dampening might cause inaccuracies in placement off shells on target, however that might be corrected with soft wear.

srai · Post by **srai** » 27 Mar 2017 06:07

srai wrote:...
ADA - 29th Annual Report 2013-2014

ADA - 30th Annual Report 2014-2015

Anyone can find the latest report?

Regarding GSH 23mm Gun tests:

2013-2014

...

Tejas (PV3):
As on 31st March 2014, total 381 flight tests (224 Hrs: 26.0 Mins) have been completed. The aircraft has flown with upgraded Flight Control System (FCS) and Avionics System software for carriage of external Stores including Drop tank. The aircraft has completed all test points envisaged for it. Currently the aircraft is used as a chase aircraft for radar and wake tests. Presently modified and GSH-23 gun integration is completed.

...
LCA Mk2:
...
(d) Internal Gun (GSH – 23) has been finalized.

...

2014-2015

...

GSH 23mm Gun Butt firing trials at Nashik were conducted during 9th August - 28th August 2014. Total of 178 rounds/bullets were fired from Tejas (PV3) aircraft successfully.

...
Tejas (PV3):
Total 387 flight tests (228 Hrs: 7.0 Mins) have been completed. The aircraft has flown with upgraded Flight Control System (FCS) and Avionics System software for carriage of external Stores including Drop tank. The aircraft has completed all test points envisaged for it. Presently the aircraft is being utilized for integration of GSH 23mm Gun which is in progress and Butt-Firing (Phase-1) completed.

...

We will need to see what has been completed in the ADA's 2015-2016 Annual Report. One can assume Phase-2 would have been completed after Phase-1 fixes/adjustments.