LCA News and Discussions

manum · Post by **manum** » 24 May 2012 20:40

in milliseconds probably. .

Being Indians we are bound to choose most uncomplicated path...

SaiK · Post by **SaiK** » 24 May 2012 20:43

manum, you must be kidding me.

manum · Post by **manum** » 24 May 2012 20:58

Hehe...making tejas was least complicated decision we coul take...

Lalmohan · Post by **Lalmohan** » 24 May 2012 21:39

SaiK wrote:^ you are saying the side hinged is better than hind hinged?

i am saying that full canopy release mechanisms have proven to be too slow to get the pilot out safely in the limited time available in the majority of ejection scenarios

SaiK · Post by **SaiK** » 24 May 2012 21:57

the alternative here, ie, blowing away polycarbonate is no guarantee to not hinder the ejection process. now, the proven slowness must have some metrics.. where, we can get to see what actually contributed to the slowness. we are discussing without data, and hence it is easy to go out of scope.

Lalmohan · Post by **Lalmohan** » 24 May 2012 22:19

canopies when they separate are affected by the airflow. they may generate lift, they may aerodynamically adhere to the airframe, they may strike the tailplane and cause instability, etc. all (or none) of which may impede the pilots progress to safety.

explosive bolts may be used to launch the canopy into the airstream, and then it may be blown away. a lot of wind tunnel studies are done to see the exact separation characteristics of the particular canopy/fuselage design and different speeds and angles of attack before deciding on the optimum model.

then there are the mock up trials, and low speed dummy trials

in short if you want data, you're going to have to dig real deep - but if it is open source, there will be mountains of it

SaiK · Post by **SaiK** » 24 May 2012 22:32

lal boss,
1. we are not bothered about canopy hitting something else (except pilot), as the case is ejection.
2. all of the models must have resulted in the most effective release (rather efficient aspect of canopy design) - focus is safety.
3. yes.. those type of data is not open.

Philip · Post by **Philip** » 25 May 2012 04:09

Remember the Paris air show where an SU-27 performed an expensive stunt to demonstrate the effectiveness of Russian ejection seats-at zero-zero alt? Watch these historic clips.

http://www.youtube.com/watch?v=Yh-kuztsE1s

http://www.metacafe.com/watch/99817/air_show_crash/

http://www.ejection-history.org.uk/Airc ... _Su-30.htm

NRao · Post by **NRao** » 25 May 2012 04:51

Three things need to happen:

1) The canopy needs to get out of the way (either the canopy shatters or it has explosives attached to the ends that explode to let the canopy loose),
2) The pilot is restraint. Automated restraining systems locks the pilot onto the seat - feet, hands, body and I think even the head (so that nothing hits anything "on the way out" - in a very good sequence the pilot is the seat, and
3) Finally the seat is ejected with substantial force to withstand all other forces.

The seat with the pilot is ejected clear of everything and the parachute opens.

ArmenT · Post by **ArmenT** » 25 May 2012 11:27

SaiK wrote:the alternative here, ie, blowing away polycarbonate is no guarantee to not hinder the ejection process. now, the proven slowness must have some metrics.. where, we can get to see what actually contributed to the slowness. we are discussing without data, and hence it is easy to go out of scope.

Very good image of an ejection where the canopy is jettisoned rather than shattered. Due to the angle that the photo was taken, it appears that the cars on the ground are close, but they were actually about 1/2 mile behind

You do have a very good point about the metrics. Turns out that there's an official video of the same incident released by the USAF, including a view from the pilot's cockpit showing the ejection taking place from inside.

From the video, it appears that the slowness is probably in the order of tenths of a second. Some unofficial documentation about the incident seems to indicate that it took approx. 4/10th of a second from when the pilot pulled the ejection handle to when the seat was starting to leave the aircraft.

SaiK · Post by **SaiK** » 25 May 2012 21:02

^freeze exactly at 1:10.. this would not be possible without the hind open.

vina · Post by **vina** » 26 May 2012 07:45

ArmenT wrote: From the video, it appears that the slowness is probably in the order of tenths of a second. Some unofficial documentation about the incident seems to indicate that it took approx. 4/10th of a second from when the pilot pulled the ejection handle to when the seat was starting to leave the aircraft.

Yes, the canopy ejection will take a couple of tenths of a second, before the seat can come out.

However, this is a lot more complex problem than through the canopy ejection. What if the plane is inverted and or rolling /yawing when the pilot ejects ? Here the pilot managed to stabilize the plane, and get the sink rate down (he knew he was going to crash) before pulling the ejection handle, what if in a totally out of control situation ?

You need to model and test the canopy separation and it's trajectory in multiple scenarios, and make sure that the seat and the canopy dont collide after ejection ..(think of ejection when the plane is inverted) , the seat comes out facing the ground and has to right itself before the main chutes can open. I think through the canopy ejection, you atleast dont have to care too much about canopy flying around in those kind of conditions and you can "outsource" the problems of seat ejection in such scenarios to the seat makers.

SaiK · Post by **SaiK** » 26 May 2012 07:51

thinking greatly ahead.. there should be some kind of laser sensor to detect obstruction to about 1000ft above or below. scenario: the jet is inverted and 50ft from Earth to crash. Instead of eject via canopy, reverse ejection from under the fuselage can be thought about.

that would be classic engineering feet.

vina · Post by **vina** » 26 May 2012 08:23

SaiK wrote:Instead of eject via canopy, reverse ejection from under the fuselage can be thought about.

that would be classic engineering feet.

Read up F104 , the ejection system proposed/ used and why it was dropped!

SaiK · Post by **SaiK** » 26 May 2012 08:50

thanks and I just read it. my thought was to eject down firing mode, only when the jet is flipped upside down.

shiv · Post by **shiv** » 26 May 2012 10:31

If an aircraft is rapidly rolling as it goes down towards the ground you can actually calculate that there is no guarantee that the cockpit will be in any particular orientation at the time of ejection. For example if the plane is rolling 360 degrees in 1.5 seconds and the cockpit is the right way up when the pilot decides to pull the eject handle. It will take about 0.2 to 0.3 secs for his brain decision to become a muscle/arm/hand action and a further 0.2 secs for the seat to start ejecting. So in that 0.5 seconds the plane will have rolled 120 degrees. If it was facing up, the cockpit will be down and off to one side when the pilot actually ejects.

symontk · Post by **symontk** » 26 May 2012 11:27

Saw a green LCA coming to land just now, did a new one took to air? or is it the NP1

Sriman · Post by **Sriman** » 26 May 2012 11:37

symontk wrote:Saw a green LCA coming to land just now, did a new one took to air? or is it the NP1

Did you mean yellow? Could be LSP7. NP1 was already painted grey, unless they stripped the paint out.

symontk · Post by **symontk** » 26 May 2012 11:42

Yes yellow

rajanb · Post by **rajanb** » 26 May 2012 12:41

symontk wrote:Yes yellow

There was the roar of a fighter over CBD. (After a long time). To me it sounded like the throaty roar of a Tejas. And it continued making passes from N to S and back. This went on for about half an hour and then silence for twenty minutes and again continued for 20 minutes. Could not get a glimpse of it.

Normally, the Test pilots do not fly on a weekend. And this was confirmed by RaghuK a few months back. So I was wondering if the IAF was checking it out and has reference to AKA's statement in parliament that Tejas has been "inducted".

In which case it may be the LSP7 and the IAF beginning to out the Tejas through its paces?

Singha · Post by **Singha** » 26 May 2012 13:29

tests happen on saturdays for sure. I had the LCH fly over my apt on a recent sat/sun (forgot the exact day).
on sundays its usually no activity.

SaiK · Post by **SaiK** » 26 May 2012 16:13

shiv ji, excellent pointer.

btw, I was not ignoring sensors which should be faster than human once engaged [assume trigger has happened].

roll is difficult .. let say we have dedicated chip that senses <5ms periods, depending on the roll, the delta time required either to come up the nearest 180 or 360* [up/down] to engage down firing or canopy open entirely depends on speed and roll rate. so, if the time to crash is within that 180* roll, then ejection any way - either canopy or down firing is no use...'cause time to respond < time to destruct., and it is debatable if ejection is better or not, and which is a better life saver tech.

It is not impossible mission, but ejection itself could be a big super computing system. sensors for human consciousness - retina scans, movement, temperature reading, breath analyzers from his helmet, perhaps even connecting to neurons via the HUD could be a future possibility.

If the systems can detect abnormal flight condition from normal - like speed and direction is oncourse to a crash, automatic ejection controls can be also thought off.. but tons of variables.

vina · Post by **vina** » 27 May 2012 09:40

Singha wrote:tests happen on saturdays for sure. I had the LCH fly over my apt on a recent sat/sun (forgot the exact day).
on sundays its usually no activity.

There was a flight yesterday (sat). At around 9:30 am, I looked up and saw a Gray LCA, with drop tanks and everything , seemed fully loaded, bank gently left over Ragigudda, in a gentle long arc heading south towards Hosur onto Krishnagiri on to it's test range that is somewhere in that region in TN.

Lets see what the sight update say, in addition to the Yellow primed ones other folks reported seeing. I saw the regular dark grey one.

koti · Post by **koti** » 27 May 2012 11:11

Of the 40 Mk I Tejas ordered, how many are trainers?

Of the Mk II lot, how many will be trainers?
Cant we more of MkI aircraft from the current lot order to be made as trainers so that they can cover the requirement when Mk II is inducted?

ArmenT · Post by **ArmenT** » 27 May 2012 12:18

SaiK wrote:shiv ji, excellent pointer.

btw, I was not ignoring sensors which should be faster than human once engaged [assume trigger has happened].

roll is difficult .. let say we have dedicated chip that senses <5ms periods, depending on the roll, the delta time required either to come up the nearest 180 or 360* [up/down] to engage down firing or canopy open entirely depends on speed and roll rate. so, if the time to crash is within that 180* roll, then ejection any way - either canopy or down firing is no use...'cause time to respond < time to destruct., and it is debatable if ejection is better or not, and which is a better life saver tech.

It is not impossible mission, but ejection itself could be a big super computing system. sensors for human consciousness - retina scans, movement, temperature reading, breath analyzers from his helmet, perhaps even connecting to neurons via the HUD could be a future possibility.

If the systems can detect abnormal flight condition from normal - like speed and direction is oncourse to a crash, automatic ejection controls can be also thought off.. but tons of variables.

In modern ejection seats, the seat also has some smart devices to figure out what to do in various situations. For instance, a separate stabilization rocket pack to prevent seat tumbling after ejection, a drogue parachute to slow down the seat and rotate it the right way prior to deployment of the main chute, device to delay opening the main chute above certain altitudes, automatically deployed oxygen pack to keep the pilot supplied with enough oxygen until they've descended to lower altitude etc.

A little googling shows that the seat used by F-15, F-16, F-22 etc. can safely deploy upside-down at 140 feet above ground and 150 knots. I would imagine that the LCA seats would be around the same specs (are they using Martin-Baker seats in LCA? If so, seat specs should be available from Martin Baker's website)

manum · Post by **manum** » 27 May 2012 20:32

I saw pressure rods embedded in seats...which act like directional backbone...won't they help the seats to eject safely upright in any angle the cockpit is....

After all its all about getting out then patachute takes over...

SaiK · Post by **SaiK** » 27 May 2012 20:41

ArmenT wrote:A little googling shows that the seat used by F-15, F-16, F-22 etc. can safely deploy upside-down at 140 feet above ground and 150 knots. I would imagine that the LCA seats would be around the same specs (are they using Martin-Baker seats in LCA? If so, seat specs should be available from Martin Baker's website)

I could get googled data for 140ft above ground, but not for "can safely deploy upside-down" at those levels.

I am sure you did not mean to say aircraft is upside-down at 140ft.

ArmenT · Post by **ArmenT** » 28 May 2012 00:03

SaiK wrote: I could get googled data for 140ft above ground, but not for "can safely deploy upside-down" at those levels.

I am sure you did not mean to say aircraft is upside-down at 140ft.

From Wikipedia:

The minimal ejection altitude for ACES II seat in inverted flight is about 140 feet (43 m) above ground level at 150 KIAS.

SaiK · Post by **SaiK** » 28 May 2012 01:21

http://www.ejectionsite.com/acesiitech.htm
gotcha. gyro stablizied!

negi · Post by **negi** » 29 May 2012 07:58

There are two crash videos of Mig-29 (1989 Paris airshow) and the Su-30 (1999 Paris airshow) , both involve ejection at very low altitude (imho at most couple of hundred feet) and at an awkward AoA where pilots make it safe to the ground.
Iirc we discussed them here some time ago.

suryag · Post by **suryag** » 30 May 2012 00:12

flight test updates on ADA website have dried up, wonder whats cooking there.

Btw June is here and monsoons might start hope ada are well prepared this time to not waste time during the monsoons

putnanja · Post by **putnanja** » 30 May 2012 00:58

suryag wrote:flight test updates on ADA website have dried up, wonder whats cooking there.

Btw June is here and monsoons might start hope ada are well prepared this time to not waste time during the monsoons

Maybe the person who updates it is on vacation, and no one else know how to do it, or don't want to do it?

member_22866 · Post by **member_22866** » 30 May 2012 11:32

suryag wrote:flight test updates on ADA website have dried up, wonder whats cooking there.

Btw June is here and monsoons might start hope ada are well prepared this time to not waste time during the monsoons

Since last 3 or 4 days i am seeing LCA at least 4 or 5 flights daily. Also they fly at much higher speed then usual.

rajanb · Post by **rajanb** » 30 May 2012 19:20

^^ Yes. Therefore I was wondering if the IAF has a couple of LSPs which they are getting the feel off?

It now could be a combination of test pilots and IAF pilots flying the a/c?

Wonder where SuryaG has gone? hope all is well with him as he used to give us a regular update on # of flights.

Gurneesh · Post by **Gurneesh** » 30 May 2012 22:29

There you go...

LCA-Tejas has completed 1864Test Flights successfully. (28-May-2012).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-347,LSP1-74,LSP2-207,PV5-36,LSP3-52,LSP4-55,LSP5-86,LSP7-3,NP1-2)

from
LCA-Tejas has completed 1852 Test Flights successfully. (16-May-2012).
(TD1-233,TD2-305,PV1-242,PV2-222,PV3-343,LSP1-74,LSP2-207,PV5-36,LSP3-51,LSP4-54,LSP5-82,LSP7-2,NP1-1)

Both NP1 and LSP7 flew again

PS info taken from http://www.ada.gov.in/archives.htm

suryag · Post by **suryag** » 31 May 2012 00:07

Thanks for the concern Rajanb sir am here and on BRF checking the LCA thread as usual many times a day. I am probably a big source of hits for the ADA website but missed yesterday's updates.

Also there doesnt seem to be any news on the progress of the AF variant(it was undergoing weapon release tests). Hope it went fine. And the monsoons will be here in a fortnight and hope ADA team is prepared for it this time.

rajanb · Post by **rajanb** » 31 May 2012 09:09

Nice to hear from you Suryag. (please drop the Sir from my name. Am a normal guy!

)

Earler on I could see the LCA, but nowadays it comes and goes in a few heartbeats. Wonder if they are flying close to MACH 1. Or breaking the sound barrier a distance away and then zipping over the airport?

I was hoping that the iaf had started flying it since AKA had announced it as "inducted".....whatever he meant by that!

Philip · Post by **Philip** » 31 May 2012 15:39

"Not Seaworthy".
Naval LCA. AWST-May 16th issue.Quoting unnamed IN sources.

In short,there are still many developmental issues with the NLCA which first flew without its tailhook.Weight,sink rate,landing gear,etc. apart from the underpowered engine (affecting STOBAR capability too) mean that the IN will not operate the limited production NLCAs from the Vik/Gorshkov,use it only from land,and wait until MK-2 arrives.Even then,the aircraft will have a modest capability only and if the IAC-2 has cats,and another type other than the MIG-29K is needed,then a twin-engined naval strike aorcraft (JSF F-35C ,F-18SH,Gripen,Rafale) will be the most likely contestants.

vina · Post by **vina** » 31 May 2012 15:51

Philip wrote:"Not Seaworthy".
Naval LCA. AWST-May 16th issue.Quoting unnamed IN sources.

........ then a twin-engined naval strike aorcraft (JSF F-35C ,F-18SH,Gripen,Rafale) will be the most likely contestants.

Natashas and DDMs are a deadly combo. Made for each other. DDM will create a twin engined JSF F-35C for the IN indeed.

Aditya_V · Post by **Aditya_V** » 31 May 2012 16:44

Vina Ji lovely catch