Bharat Rakshak

^^^ There is that High AoA pdf article that gives all the info one needs to understand this. All jingos need to read that article.

IIRC LCA can go to 35 deg AoA, but there are some limitations due to instabilities in yaw and roll that limit the designers to 24 deg. Going beyond it will mean having a perfect understanding of the aircraft characteristics and required FBW laws. The article mentions that 24 deg is a safe limit and further testing will increase it to the 'expected' (probably what IAF wants) limit of 26 deg.

and you are right, a lot of what I said in the last few comments is gleaned that article ... also B Harry had stated some of these details in his writings.

AoA value of 35 deg is the maximum achievable figure as per design specifications.

Gurneeshji,
Can you please post a link to that article.. Should make for an interesting read.

thanks.

afaik the max AoA of F-16 and F-18 are claimed as 30' and 40' respectively with the F-15E around mid 20s. does it sound right?
rafale and EF would be up around 28-30 range?

He is speaking of this
http://www.scribd.com/doc/78345390/Approach-to-High-Angle-of-Attack-Testing-of-Light-Combat-Aircraft-LCA-Tejas

Additional reading:
http://nal-ir.nal.res.in/9158/1/312.pdf

the raptor I read can do high alpha - about 60*. I have no idea how that transforms to a risk factor for landing at that angle. there must be extreme thrust to handle, high drag-no stall and plus fantastic sensors to collobroate with alphas to automatically reduce speed and angle, within safety limits.- the wheels must touch right?

Indranilroy ji, Thanks for the paper. Do you know if design optimization in terms of code is also done in tandem with CFD codes for LCA or any other aircraft right now?

Thrust vectoring. IIRC the Su 30, MiG 35 and other TV variants can do something similar or better.

^^Thanks indranilroy.
Superb primer by Wg. Cmdr. Vikram Singh, in plain English. I am glad that the LCA team is openly publishing the characteristic, challenges and testring strategies etc. I am not sure if this is unique to LCA or if other countries publish so openly as well.

It appears that the testing philosophy is "Departure prevention" rather than actual "spin recovery", while being prepared for an actual spin recovery in the event of a departure.

I am quoting some pieces here because it is extremely interesting for me personally and I am assuming it will be for some of you as well.

On some of the challenges:



On testing Philosophy:


On recovery techniques

How do they measure corrections from metrics alone or the design itself has certain tolerance and limiting factors that is included?

for example, let us say inlets.. when you start your design, assume you don't use CFD.. and then you run over CFD, and it points out certain corrections.

Now, you limitations again is with design factors as well. Did they begain designing from CFD given inputs, or they started off with some general baseline design, and started applying the correction factors?

What about the air intakes? They have to worry about compressor stall as well at high AoA.

^should be well covered by stator vanes angles (digital controls) right? doesn't the GE404 one have it? and ours is fully FADEC-ed. Or is that still outside of the game plan here?

I meant exactly as I said ... I just do not know ... I do not know anybody who is privy to such information.

I was just answering from the aerodynamics point of view. What we know openly, I have not seen a graph where there is any deviation from linearity of CL max till 30 degrees. However the same cannot be said about roll and yaw. According to the paper, they see a fall in the moments at about 25 degree. The author says that the rudder can be used to artificially provide stability upto 30 degrees. However, to be on the safer side they are going to restrict AoA to 26 degrees.

I don't know anything about the intakes. I have not seen any information in open literature.

No 'ji' please .

I am sorry I did not get what you are asking. Are you asking of optimizations in CFD codes? Or design optimizations found using CFD analysis incorporated into the prototypes?

For the first question, I don't know, but I would guess so ... I know NAL does some work related to this ... Otherwise, I work in HPC and will be available for hiring in 2-3 years

If you are speaking about the second question, the answer is definitely an yes. You can see some of the optimizations in LSP 7.

That is because of TV. http://www.sfte-ec.se/data/Abstract/A2000-II-02.pdf

Oh my. What a fabulous article. An arcane and detailed subject written with great clarity. +10

Ive always wondered if HAL have built in house CFD programs for LCA or they used a software from third parties.....

Hoping for the former, i bet we are not short of programmers cum aerospace engineers in this country...

HAL is the production agency and ADA is doing all the R&D related with LCA. AFAIK ADA uses commercially available CFD packages and they also have the capability of CFD programming so no worries here.

^^Thanks

Here is a video of scale model of F104 tested in a wind tunnel with spin recovery chutes

Indranilroy , thanks, I meant the second one, it would be great to know how they carried out the optimizations. HPC! wow, nice to know. I work in CFD looking into CUDA now.

now, raptor is successful with pitch-axis vectoring alone.. that increases the stealth characteristics as well when compared to pak-faish rears that does 360* tv. perhaps roll and yaw need not required high vectoring and it fits well to augment thrust on pitch alone.

now, if the thermal signature does only reduce by 30%, then I would choose 360% tv, and use a retractable probe based infra jammer and dispense flares when approached from rear. why waste money, when this is more elegant and efficient way to destroy the chaser say at 50ft away from rear., and focus on the kill mission.

How can I see that article? Every one of my browsers is horribly mangling that page (Firefox, Chrome, IE)?

There is an article here

http://defensetech.org/2010/12/31/j-20-vs-f-35-one-analysts-perspective/#comment-267669

Can we analyze how relevant is LCA is with these points.

Merlin,
You have bijjli dak..

Mucho thanks. I hadn't seen that article before so much to digest in there.

You are welcome ji.. Have sent another e-daak, on a different topic though..

Flight test update

LCA-Tejas has completed 1827 Test Flights successfully. (13-April-2012).
(TD1-233,TD2-305,PV1-242,PV2-220,PV3-336,LSP1-72,LSP2-205,PV5-36,LSP3-47,LSP4-49,LSP5-80,LSP7-2)

from

LCA-Tejas has completed 1824 Test Flights successfully. (11-April-2012).
(TD1-233,TD2-305,PV1-242,PV2-220,PV3-336,LSP1-71,LSP2-205,PV5-36,LSP3-47,LSP4-49,LSP5-78,LSP7-2)

Flight test update

LCA-Tejas has completed 1828 Test Flights successfully. (16-April-2012).
(TD1-233,TD2-305,PV1-242,PV2-220,PV3-337,LSP1-72,LSP2-205,PV5-36,LSP3-47,LSP4-49,LSP5-80,LSP7-2)

from

LCA-Tejas has completed 1827 Test Flights successfully. (13-April-2012).
(TD1-233,TD2-305,PV1-242,PV2-220,PV3-336,LSP1-72,LSP2-205,PV5-36,LSP3-47,LSP4-49,LSP5-80,LSP7-2)

Soon expect a DMM writen article saying "Since LCA can not carry at least six Agni 5 (which itself is a outdated missle) under each of its wings it is a waste fighter. India should purcase F16 which will carry 12 Minutemen under each of its wing which can be used againt Maldeivs"

Flight test update

LCA-Tejas has completed 1830 Test Flights successfully. (16-April-2012).
(TD1-233,TD2-305,PV1-242,PV2-220,PV3-338,LSP1-73,LSP2-205,PV5-36,LSP3-47,LSP4-49,LSP5-80,LSP7-2)

from

LCA-Tejas has completed 1828 Test Flights successfully. (16-April-2012).
(TD1-233,TD2-305,PV1-242,PV2-220,PV3-337,LSP1-72,LSP2-205,PV5-36,LSP3-47,LSP4-49,LSP5-80,LSP7-2)

4 flights in one day

Any news on NLCA? Been quite some time since its anticipated first flight

nope.. AMCA thread is appropriate. LCA has many enablers, but the program itself is not chartered to be compared with these two.

Good news on NP1. FRRB clears first flight.

http://tarmak007.blogspot.com/2012/04/f ... t-one.html

yay! eagerly waiting for the new AoAs.

Very good news if true

Eagerly waiting for NP-1 to Touch the Sky with Glory

clearance means, the undercarriage issue sorted out, what to watch would be the moveable levcon in action. AOA!