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[kingdurgaking]

this is what the article concludes that we do require changes in the design of the fuselage if we change the design of the air intakes but no where in the article suggest that there is a change necessary required in the exhaust if there is any change in the design of the air intake.

Air intakes are necessary for all vehicles propelled by airbreathing
means, whether they be aircraft, missiles,
helicopters or, in the future, reusable space launchers.
They will directly condition the propulsive performance
(thrust, drag, weight, thermal properties, lift) of the
vehicles in which they are mounted. They are subject to a
multitude of constraints (Mach number, angle of attack
and yaw angle, possible injections, discretion, engine
failure, among others).
The first step in air intake design is thus to "clearly
identify all of the air intake's specifications".
After a short phase in which the air intake is defined alone
comes the phase in which the external aerodynamic field is
effectively considered with its over- and under-speeds,
vortices, boundary layers, transverse gradients, nose and
other effects.

The second step is thus to "find the best location for the
air intake(s) and, if possible, modify the upstream part
of the fuselage to improve the captured air flow".
Air intakes have very complex internal flows, including
sub-, trans-, and supersonic zones simultaneously. There
are many interactions (shock/shock, shock/boundary layer,
vortex/wall, corner effect) and they are generally
combined. Many non-steady aspects are to be considered,
and notably the buzz which is critical for structural
dimensioning and operating limits. The air intake's
matching with the engine that it supplies must always be
ensured.
The third step is then to "carry out some calculations,
but use essentially previous experience (bibliography,
personal knowledge) and wind tunnel tests at high
Reynolds numbers".

Air intakes must be designed by a "System" approach.
Optimising them is a long and difficult process.

Fine dude... You are just saying rectangular is not mandatory.. accepted ...we are not saying it is rectangular.. we are just foreseeing that Rectangular intake can be an option because it is there on a plane which is hosing the same engine...

And from where did you get that dimensions are different.. can we have your source?.. I have couple of source saying dimensions are same.. do you want me to post it?? let me see your source first

 

[satishkumarcsc]

F414-GE-400 / F414-GE-INS6, F414G

F404-GE-400

 

[kish]

Kish we don't have to justify our self to idiot.

Just ignore the troll.

copy that...

 

[ganimi kawa]

S according to me...a rectangular intake is not mandatory unless the LCA is designed for stealth or stealthy purposes. The LCA is already delayed and so i dont want to delay it further....

I do not agree with this!

Surfaces at 90 degrees to one another reflect radar waves right back to where they came (so rectangular engine intakes, and vertical and horizontal tails, make an airplane easy to pick out on radar). If we want to make the LCA more stealthy then "rectangular" air intake is something we must avoid!

Though, I agree with you that shape change is not required in the LCA air intakes to satisfy the hunger of GE414 engines. The present shape will work just fine.

Here's a pic of LCA intakes...

Now , please notice the huge but similar shaped intakes in the sea harrier.

Shape is not a problem AFA delivering enough air to the engines is concerned.


P.S. Do you mean diamond shaped intakes?

 

[kingdurgaking]

F414-GE-400 / F414-GE-INS6, F414G

F404-GE-400

cant you see dimensions are same ... it differs only by weight..

414

Dimensions: Diameter 890 mm, Length 3.9 m
Weights: Max Weight 1,109 kg (2,445 lb)

404


Dimensions: Diameter 890 mm, Length 3.9 m
Weights: Max Weight 991 kg (2,185 lb)

 

[satishkumarcsc]

I do not agree with this!

Surfaces at 90 degrees to one another reflect radar waves right back to where they came (so rectangular engine intakes, and vertical and horizontal tails, make an airplane easy to pick out on radar). If we want to make the LCA more stealthy then "rectangular" air intake is something we must avoid!

Though, I agree with you that shape change is not required in the LCA air intakes to satisfy the hunger of GE414 engines. The present shape will work just fine.

Here's a pic of LCA intakes...

Now , please notice the huge but similar shaped intakes in the sea harrier.

Shape is not a problem AFA delivering enough air to the engines is concerned.

Thats just the engine...the gearbox, FADEC and atomizer accomodation must be taken into consideration...


P.S. Do you mean diamond shaped intakes?

rectangular intakes or rhomboidal intakes...it isnt the matter...the reduction of turbulence in the airflow is what matters....
And i was replying to the post of the person above me....Its kinda hard to type with a blackberry u see....
So with that you must take gearbox, atomizer into consideration along with FADEC..

 

[kingdurgaking]

I do not agree with this!

Surfaces at 90 degrees to one another reflect radar waves right back to where they came (so rectangular engine intakes, and vertical and horizontal tails, make an airplane easy to pick out on radar). If we want to make the LCA more stealthy then "rectangular" air intake is something we must avoid!

Though, I agree with you that shape change is not required in the LCA air intakes to satisfy the hunger of GE414 engines. The present shape will work just fine.

Here's a pic of LCA intakes...

Now , please notice the huge but similar shaped intakes in the sea harrier.

Shape is not a problem AFA delivering enough air to the engines is concerned.


P.S. Do you mean diamond shaped intakes?

I want to add a point for rectangular/parallelogram intake .. The area of Air that can enter is more than the elliptical one... for the given dimension.. like the one in saab gripen

 

[kish]

yes that is what I am tying to tell.... Air Intakes must be done according to system approach. That take s a lot of time to develop. And hence the delays that are plaguing the LCA will increase further more.

You have now found out the designing of the air intakes directly spells the delay of the aircraft because there is a lot of things affecting the change of intakes.

LCA being a 95% composite surface area airframe has many problems relating to heat. Heat is very important when it comes to composite design and heat must be dissipated. Heat in a particular part is a big problem. I am a dentist...and that is why i give a bevel so as to dissipate the stress and heat in a particular area. That is kinda impossible in a rectangular air intakes.

S according to me...a rectangular intake is not mandatory unless the LCA is designed for stealth or stealthy purposes. The LCA is already delayed and so i dont want to delay it further....

next is the discussion of shock and vortex formation....everyone knows in basic aerodynamics the shock and vortex formation takes place at sharp edges when the air flow is turbulent. The rectangular exhausts that u mention causes more vortices because of sharper edges and hence a lot of air pockets that choke the engine....that is a major concern while redesigning the air intakes from an already existing form to another...

http://espace.uq.edu.au/eserv/UQ:121369/Hua_afmc_16_07.pdf

http://www.engineeringletters.com/issues_v16/issue_3/EL_16_3_20.pdf

This shows that the air intake must also take into consideration the vortex formation in the sharp edges of the rectangular air intakes. Now you might get a Gist of what i am trying to say.

FBW is something that is gonna be switched off during ACM...so it is a hard thing to ignore...but is Close combat the pilot s going to push the aircrafts into the flight envelopes where the aircraft has rarely been in sustainance. Experienced pilots might avoid all those but in war time it is hard to tell if experienced pilots will be flying all the time...attrition must e taken into consideration.

, , , , , look my teeth

kidding.................

satish .. i understood ur points but as we know
LCA-II will powered by new engine so there will be work on fuselage in that case we can also add and test rectangular/parallelogram air intake

again ur have a good point that for rectangular/parallelogram air intake will cause new problem of fluid dynamics [dont know much of that .. even forgot burnaulie's theorem] and we can face a delay ..

but again
++ study off new air intake will help in mca .. as u say rectangular/parallelogram intake consider when we need stealth, ....

my one point size of air intake have to change in normal case too coz new higher thrust engine need to suck more air inside


summary is ,, (consider no rectangular/parallelogram intake)
fuselage already need some work
air intake already need some work
work on mca also will start and so new air intake for same...

so .. we can think to have rectangular air intake in case the give an advantage ....

these are just my view ,,, feel free to correct me,,,,,,

no discussion about MMR . . . . is there somebody have good idea about it ,,,

 

[satishkumarcsc]

, , , , , look my teeth

kidding.................

satish .. i understood ur points but as we know
LCA-II will powered by new engine so there will be work on fuselage in that case we can also add and test rectangular air intake

again ur have a good point that for rectangular air intake will cause new problem of fluid dynamics [dont know much of that .. even forgot burnaulie's theorem] and we can face a delay ..

but again
++ study off new air intake will help in mca .. as u say rectangular intake

my one point size of air intake have to change in normal case too coz new higher thrust engine need to suck more air inside


summary is ,, (consider no rectangular intake)
fuselage already need some work
air intake already need some work
work on mca also have will start and so new air intake for same...

so .. we can think to have rectangular air intake in case the give an advantage ....

these are just my view ,,, feel free to correct me,,,,,,

no discussion about MMR . . . . is there somebody have good idea about it ,,,

Think of the delay mate...its huge...with all the mods to the airframe and to the FADEC and the comp programming it will take a long time...and the LCA will be pushed even further...AMCA yes...but it is being designed with rhomboidal intakes from the start....

 

[kingdurgaking]

Think of the delay mate...its huge...with all the mods to the airframe and to the FADEC and the comp programming it will take a long time...and the LCA will be pushed even further...AMCA yes...but it is being designed with rhomboidal intakes from the start....

Buddy on the lighter note .. we are just debating.. you no need to worry about delays as HAL and ADA would have already planned and would have given a road map to IAF.. which would have been freezed by now..

you getting worried on fictional changes and we getting worried because you got worried .. so chill what ever supposed to happen will happen....

 

[kish]

Think of the delay mate...its huge...with all the mods to the airframe and to the FADEC and the comp programming it will take a long time...and the LCA will be pushed even further...AMCA yes...but it is being designed with rhomboidal intakes from the start....

hmm i know putting anything new in fighter jet is long term process of many sub process ,,
just my one query that ... we already have to work in both area (intake & fuselage) coz of engine .. and we already have to study new air intake for amca ,,, so is this not a possible that LCA-III can have some new feature including new intake after some time may be after some squadron of LCA-II aready produced (eg ,, after 50 LCA-II) ... but not at the cost of delay ,,, we can keep running our production line and when we have enough new things ready anad tested to add we can launch new version ,, so production will not suffer ..

 

[ganimi kawa]

rectangular intakes or rhomboidal intakes...it isnt the matter...the reduction of turbulence in the airflow is what matters....

Come on, doc! It's like saying Le Forte I or Le Forte II.......it isn't the matter!

And i was replying to the post of the person above me....Its kinda hard to type with a blackberry u see....
So with that you must take gearbox, atomizer into consideration along with FADEC..

I can totally empathize with you!


Fun apart, I totally agree with you about the difficulties and the time penalty for changing LCA mk2 intakes. Size increase is much more probable!

@ kish

satish .. i understood ur points but as we know
LCA-II will powered by new engine so there will be work on fuselage in that case we can also add and test rectangular/parallelogram air intake

There is no need to tamper with the design of a product variant if you want to test rectangular/parallelogram air intake. One craft can do the job!

In fact, L.S.P. 6 of the LCA mk1 has been desiganted for experimental purposes. This craft can be used for the said purpose.

Here is F16 testbed testing the DSI Intakes.

 

[kish]

Lemme correct my self .. . the GE F404 and F414 have same dimension ,, so my arguments are on stand by


and one question ,, does there is need to work on size fuselage and air intake just because F414 engine alone ,,,