LCA news and discussion

[Wickberg]

well gripen is the leader as far as STOL characteristics are concerned. so taking it as the standard isn't quite fair.
but do you mind if I ask for a source on those figures ? 800 km with that load and an EFT (what capacity ?) in lo-lo-hi sounds too good to be true, even if I account for the fact that engines give much better performance in swedish climes.

The source? Books, magazines, newspapers, television plus the fact I know a lot of people who works at F16/20 airbase in Uppsala. It´s not a secret, it´s a common knowledge and I even think SAAB has those numbers in their homepage (and the Swedish Air force). Since WWII the tactic of the Swedish Air force have been to fly low over the Baltic Sea to attack ports were the russian navy would assemble their troops onto ships, and ever since Lansen came into service it must meet this requirement (back then the fighters was also suppose to carry nuclear bombs to be dropped on Baltic cities). But the climate over the Baltic sea is probably better for an aircrafts performance then in India, how much better I don´t know. It should be noted however that the Gripen has been flying in every continent of the world (except Australia and Antarctica) without experience any problem.

Speaking of landing / take off. Look at this video from South Africa when a Mirage F1 and a Gripen taking off at the same time and compare the performance...

http://www.youtube.com/watch?v=nAHQdHGWwf0

[Rahul M]

A take off distance of 1250 meters is still a lot for a fighter. Compare that video to this of a Gripen landing/taking off from a road base...

http://www.youtube.com/watch?v=QJQKCUjcslM

thanks a lot for that vid ! the take-off run is 19 seconds, 2:41 to 3:00 with 6 A2A missiles and a centreline tank. that compares pretty well with the 22 seconds for a LCA with a little heavier load at the punishing environs of leh !
now, you are telling me that's 400m ?
by my earlier estimate that would give the gripen a take-off distance of 1319 m ! clearly I was overestimating for the LCA too.
assuming similar avg speeds, the first video take-off distance (which I estimated to be 1250m) should be well within 500m.

[Wickberg]

thanks a lot for that vid ! the take-off run is 19 seconds, 2:41 to 3:00 with 6 A2A missiles and a centreline tank. that compares pretty well with the 22 seconds for a LCA with a little heavier load at the punishing environs of leh !
now, you are telling me that's 400m ?
by my earlier estimate that would give the gripen a take-off distance of 1319 m ! clearly I was overestimating for the LCA too.
assuming similar avg speeds, the first video take-off distance (which I estimated to be 1250m) should be well within 500m.

I don´t know how you estimate things, I never said the take off in that video was 400 meters, I said I have witnessed a Gripen taking off from a roadbase in (less) then 400 meters. What I commented was a sign in the Defexpo from HAL claiming that the LCA needed 1700 meters of take off, I thought it sounded very much and it must be wrong.

FYI: The Swedish roadbases are 800 meters long (there´s of course a lot of safety margins) so if that Gripen would have needed 1300 meters to take off it would have ran straight into the forest....

[nachiket]

One thing to note is that the new engine on the MkII might probably improve take-off performance due to the additional thrust.

[Wickberg]

One thing to note is that the new engine on the MkII might probably improve take-off performance due to the additional thrust.

The Gripen NG got a new engine with more thrust, I have never heard anything about improving take-off performance. Why should that be in the case of LCA MkII? I think it has more to do with the design of the fuselage...

[Rahul M]

FYI: The Swedish roadbases are 800 meters long (there´s of course a lot of safety margins) so if that Gripen would have needed 1300 meters to take off it would have ran straight into the forest....

I didn't mean to knock you over that 400m tidbit, I genuinely wanted a figure so that I could calibrate the video estimates. I do see one thing though, both these have very similar time for take-off runs.

btw, what would you estimate that gripen take-off distance to be ?

The Gripen NG got a new engine with more thrust, I have never heard anything about improving take-off performance. Why should that be in the case of LCA MkII? I think it has more to do with the design of the fuselage...

take-off performance depends on two factors, minimum take-off speed, which is a function of the fuselage , as you say (plus weight) and how quickly you reach it, which is a function of the engine. now AFAIK, most modern fighters don't go full afterburner on take-off, unless they are max loaded.
a higher performance engine then will not give better take-off performance if it doesn't power up any faster than the lower performance engine. given gripen's already excellent take-off performance I don't think saab was particularly interested in this aspect of the engine.

[ArmenT]

Doing some madarassa math here using laws of physics and a few assumptions. Since I'm a scheming chankiyan yindoo, it is only right that I should do my calculations in scheme.

Code: Select all

;; Take off distance calculations of Gripen and Tejas by Armen T
;; Assumption: Acceleration is linear
(define take-off-speed-in-kmph 250)
(define (square x) (* x x))
(define (kmph->m_per_sec kmph) (/ (* kmph 1000) 60 60)) ; Km per hour to m/sec 
(define (calc-acceleration u v t) (/ (- v u) t)) ; v = u + a*t, therefore a = (v - u)/t
(define (calc-distance u a t) (+ (* u t) (* 0.5 a (square t)))) ; s = (u * t) + (1/2 * a * t^2)
(define take-off-speed (kmph->m_per_sec take-off-speed-in-kmph))
(define gripen-takeoff-time 19)
(define tejas-takeoff-time 22)

(define gripen-acceleration (calc-acceleration 0 take-off-speed gripen-takeoff-time)) 
(define tejas-acceleration (calc-acceleration 0 take-off-speed tejas-takeoff-time))
(display "Gripen Takeoff Distance: ")
(display (calc-distance 0 gripen-acceleration gripen-takeoff-time))
(newline)
(display "Tejas Takeoff Distance: ")
(display (calc-distance 0 tejas-acceleration tejas-takeoff-time))
(newline)

I made the assumption of take off speed of 250 kmph per Rahul M's post above. However, I think that this assumption might be a bit high. For one thing, F-16's take off speed with normal configuration is 120-130 knots which works out to around 220-240 kmph and I would assume that both Gripen and Tejas should really be able to take off around this speed, but I defer to the more general guess. I've also made the assumption that the acceleration is linear which is not really true for jet-engines, but good-enough for our purposes. Take off times of Gripen and Tejas are assumed to be 19 seconds and 22 seconds from the two vids that RahulM has mentioned

With that said, here are the results:

Code: Select all

Gripen Takeoff Distance: 659.7222222222222
Tejas Takeoff Distance: 763.8888888888889

As you can see, both are under 800 meters.

[Wickberg]

I didn't mean to knock you over that 400m tidbit, I genuinely wanted a figure so that I could calibrate the video estimates. I do see one thing though, both these have very similar time for take-off runs.

btw, what would you estimate that gripen take-off distance to be ?

take-off performance depends on two factors, minimum take-off speed, which is a function of the fuselage , as you say (plus weight) and how quickly you reach it, which is a function of the engine. now AFAIK, most modern fighters don't go full afterburner on take-off, unless they are max loaded.
a higher performance engine then will not give better take-off performance if it doesn't power up any faster than the lower performance engine. given gripen's already excellent take-off performance I don't think saab was particularly interested in this aspect of the engine.

I would estimate the take off in the first video to be about 500 meters. (One is loaded with AAMs and a fuel tank, the other one with 2 RBS 15, 2 Mavericks, Sidewinders and a fuel tank). The reason why I do that is because that is the normal take off distance during exercises in Sweden during peace time with all the safety protocol regarded.

And to be frank, I don´t think your way of estimate take off distances is the best one- every air craft accelerate in different speeds. (as you can see in the Mirage F1 vs Gripen video). To be sure, just measure the distance of the airfield (walking beside the airfield is one way, boring as hell but idiot proof). And make mental "points" along the field every 100 meters so you know were the aircraft gets airborne. In Sweden this is more simple since they still use road bases sometimes. Road bases are common civilian roads that are (of course) open to the public to drive on. So you just have to drive your car and set the mileage counter at zero when you come to such a stretch, after that it´s pretty simple to know the exact take off distance an aircraft needs.

This is however a non-issue in this thread I think. The IAF never asked for a requirement of the LCA to be able to take off and land in less then 800 meters. The Swedish Air force did when they wanted a replacement for the Draken and Viggen, because we used a system of dispersed bases (Bas-90) by using road bases. At that time (early 1980s) only two aircrafts could do that, Gripen and the F/A-18 Hornet (in landing they had to rely on arrestor hooks). India don´t use roadbases, and the LCA does´nt have need that capability.

BTW; I have never been specially impressed by the Gripen since I grew up with the Viggen. And seeing a Viggen landig and taking off is a whole other story. The sound alone makes your ears bleed and your body shaking from the toes to the head, it´s truly breathtaking... Like the Gripen it was designed for STOL and operating from short roadbases. I just love those aircraft carrier landings.

http://www.youtube.com/watch?v=zpxz_-ELi6U

[Wickberg]

Doing some madarassa math here using laws of physics and a few assumptions. Since I'm a scheming chankiyan yindoo, it is only right that I should do my calculations in scheme.

Code: Select all

;; Take off distance calculations of Gripen and Tejas by Armen T
;; Assumption: Acceleration is linear
(define take-off-speed-in-kmph 250)
(define (square x) (* x x))
(define (kmph->m_per_sec kmph) (/ (* kmph 1000) 60 60)) ; Km per hour to m/sec 
(define (calc-acceleration u v t) (/ (- v u) t)) ; v = u + a*t, therefore a = (v - u)/t
(define (calc-distance u a t) (+ (* u t) (* 0.5 a (square t)))) ; s = (u * t) + (1/2 * a * t^2)
(define take-off-speed (kmph->m_per_sec take-off-speed-in-kmph))
(define gripen-takeoff-time 19)
(define tejas-takeoff-time 22)

(define gripen-acceleration (calc-acceleration 0 take-off-speed gripen-takeoff-time)) 
(define tejas-acceleration (calc-acceleration 0 take-off-speed tejas-takeoff-time))
(display "Gripen Takeoff Distance: ")
(display (calc-distance 0 gripen-acceleration gripen-takeoff-time))
(newline)
(display "Tejas Takeoff Distance: ")
(display (calc-distance 0 tejas-acceleration tejas-takeoff-time))
(newline)

I made the assumption of take off speed of 250 kmph per Rahul M's post above. However, I think that this assumption might be a bit high. For one thing, F-16's take off speed with normal configuration is 120-130 knots which works out to around 220-240 kmph and I would assume that both Gripen and Tejas should really be able to take off around this speed, but I defer to the more general guess. I've also made the assumption that the acceleration is linear which is not really true for jet-engines, but good-enough for our purposes. Take off times of Gripen and Tejas are assumed to be 19 seconds and 22 seconds from the two vids that RahulM has mentioned

With that said, here are the results:

Code: Select all

Gripen Takeoff Distance: 659.7222222222222
Tejas Takeoff Distance: 763.8888888888889

As you can see, both are under 800 meters.

The easiest way to determine this would be be if HAL just had an official website were all the figures was official. Instead of people sitting at home doing "Madrassa math" based on some made belief calculations. And remember, all this started with a picture of a sign from the DefExpo at the Tejas exhibition. As far as we know the company who made that sign could have f*cked up big time.

[ArmenT]

^^^^^
Yep, absolutely true. Only reason I went through the exercise is because the quoted figures of 1300 meters and 1700 meters seemed way too high to me too. Even with worst-case scenario and over-conservative calculations, you can still see that we get much lesser figures for take off distance. The signboard must be wrong.

[Wickberg]

^^^^^
Yep, absolutely true. Only reason I went through the exercise is because the quoted figures of 1300 meters and 1700 meters seemed way too high to me too. Even with worst-case scenario and over-conservative calculations, you can still see that we get much lesser figures for take off distance. The signboard must be wrong.

Plus, the combat radius most be wrong. 300 km is even less then some WWII fighters....

[Sanku]

^^^^^
Yep, absolutely true. Only reason I went through the exercise is because the quoted figures of 1300 meters and 1700 meters seemed way too high to me too. Even with worst-case scenario and over-conservative calculations, you can still see that we get much lesser figures for take off distance. The signboard must be wrong.

Plus, the combat radius most be wrong. 300 km is even less then some WWII fighters....

They interchanged the actual numbers of combat radius and take off length?

[Wickberg]

Not to be harsh on the Indian LCA-lovers, but all this kind of shows how the LCA is managed. I have said it before and I will say it again, HAL really needs to hire some people who knows about public relations. It is a High-tech firm and they don´t even have a decent web page to present their products. Even a 13 year old Swedish bimbo would have a blog page that is more presentable then HALs. And the Indian air force, don´t they care about their image to the public? Where are theirs LCA page? For someone looking at this from the outside it seems very strange, Indians seems very nationalistic but when it comes to endorsing their own products you get the feeling they are ashamed of them and trying to do anything to sabotage it...

[Wickberg]

They interchanged the actual numbers of combat radius and take off length?

So the LCA actually requires 300 km to take off and have a combat radius of 1,7 km?

[Rahul M]

The easiest way to determine this would be be if HAL just had an official website were all the figures was official.

that is asking for too much ! they can make nuclear submarines, ICBMs and mach 2 fighters but can't put up a decent website with relevant info. best of it, HAL recently closed down its PR dept.

And to be frank, I don´t think your way of estimate take off distances is the best one- every air craft accelerate in different speeds. (as you can see in the Mirage F1 vs Gripen video).

no sir. it can actually be quite accurate for our need. and if you noted the F1 took much longer to take-off. I made a stupid mistake in my first estimate. assuming constant acceleration (which shouldn't be too far off) the average speed of the total take-off run will always be half of the final velocity i.e the speed at take off, irrespective of acceleration. it's simple high school dynamics. in that case, if you know the take-off speed, the time of the take-off run will give you the take-off distance.

take the gripen take-off for instance. 500m in 19 sec gives it an avg speed of 26.32m/s or 94.7 kmph. that means its take-off speed was 190kmph ! that's impressive but possible. we know that a su-27 took off at 180kmph.

the LCA estimation then becomes quite easy, we can assume take-off speed to be around 220kmph, give or take 10kmph depending on payload. at an avg speed of 110kmph (30.56m/s) it takes off in 22 sec at leh = 672 m take-off distance.

taking all the possible inaccuracies into consideration I would think that even the most heavily laden LCA should manage to take-off within 800m.

[Rahul M]

They interchanged the actual numbers of combat radius and take off length?

So the LCA actually requires 300 km to take off and have a combat radius of 1,7 km?

[Sanku]

>>Sanku: They interchanged the actual numbers of combat radius and take off length?

So the LCA actually requires 300 km to take off and have a combat radius of 1,7 km?

Numbers dear Wick, numbers; not the units capice?

Rahul M

[ArmenT]

the LCA estimation then becomes quite easy, we can assume take-off speed to be around 220kmph, give or take 10kmph depending on payload. at an avg speed of 110kmph (30.56m/s) it takes off in 22 sec at leh = 672 m take-off distance.

Yep, at 220 kmph (which is where I did my first calculation assuming the same take-off speed as F-16. I personally thought 250 kmph was way too high), I got 672 m take-off distance for LCA too.

[Rahul M]

Not to be harsh on the Indian LCA-lovers, but all this kind of shows how the LCA is managed.

no it doesn't. it only shows how the PR function is managed. frankly, the govt owned co's couldn't care less about PR, their primary customers (India's armed forces) don't get their feed from the websites, that relation is direct. these co's therefore have no incentive (in their mind) to maintain a decent website.

the best example is ISRO, they are going great guns in all aspects of space exploration, sending a highly successful moon mission and what not but their website was a disgrace a few months back. mind it, it still is a disgrace but a little less so. http://isro.org/ it looks like something a 12 year old kid will put up.

[Wickberg]

The easiest way to determine this would be be if HAL just had an official website were all the figures was official.

that is asking for too much ! they can make nuclear submarines, ICBMs and mach 2 fighters but can't put up a decent website with relevant info. best of it, HAL recently closed down its PR dept.

And to be frank, I don´t think your way of estimate take off distances is the best one- every air craft accelerate in different speeds. (as you can see in the Mirage F1 vs Gripen video).

no sir. it can actually be quite accurate for our need. and if you noted the F1 took much longer to take-off. I made a stupid mistake in my first estimate. assuming constant acceleration (which shouldn't be too far off) the average speed of the total take-off run will always be half of the final velocity i.e the speed at take off, irrespective of acceleration. it's simple high school dynamics. in that case, if you know the take-off speed, the time of the take-off run will give you the take-off distance.

take the gripen take-off for instance. 500m in 19 sec gives it an avg speed of 26.32m/s or 94.7 kmph. that means its take-off speed was 190kmph ! that's impressive but possible. we know that a su-27 took off at 180kmph.

the LCA estimation then becomes quite easy, we can assume take-off speed to be around 220kmph, give or take 10kmph depending on payload. at an avg speed of 110kmph (30.56m/s) it takes off in 22 sec at leh = 672 m take-off distance.

taking all the possible inaccuracies into consideration I would think that even the most heavily laden LCA should manage to take-off within 800m.

I think we can all agree on that the sign on the DefExpo must have been wrong. It is as simple as that. And please do not call me "sir", I am not your father and you are a moderator here, if some one should call anyone "sir" it would be me calling it to you. I know it is a polite thing to do and that Indians are the most polite people in the world it just feels very strange to be called "sir" by a moderator. I get the same feeling when I´m going trough US customs and 2 meter black guy orders me to empty my suit case on the table but he follows it up with "kindly, Sir". I´m from Sweden, I´m nuts, not used to it its all...

Off the record I think it would have been great if we could reverse time 20-30 years. From that time and forward Sweden and India basically had the same needs in many defense purchases. New fighter (LCA, Gripen), new howitzers (Bofors FH-77, ?), new subs (Kockums A-17/19, U-209/Scorpene), new tanks (Leopard II, T-90), new APC (Combat vehicle 90, ?) etct etc. All these had basically the same requirements, if we would have worked together it could have been the beginning of a beautiful friendship....

[Carl_T]

Not to be harsh on the Indian LCA-lovers, but all this kind of shows how the LCA is managed. I have said it before and I will say it again, HAL really needs to hire some people who knows about public relations. It is a High-tech firm and they don´t even have a decent web page to present their products. Even a 13 year old Swedish bimbo would have a blog page that is more presentable then HALs. And the Indian air force, don´t they care about their image to the public? Where are theirs LCA page? For someone looking at this from the outside it seems very strange, Indians seems very nationalistic but when it comes to endorsing their own products you get the feeling they are ashamed of them and trying to do anything to sabotage it...

Why does their PR really matter? If anything, we would want everyone to think it's crap and underestimate it, until they find out to their own peril!!!!


Although it wouldn't do anything for deterrence.

[ArmenT]

Why does their PR really matter? If anything, we would want everyone to think it's crap and underestimate it, until they find out to their own peril!!!!
Although it wouldn't do anything for deterrence.

Wickberg does have a point though. I used to be one of those "who cares what it looks like as long as it works" type chaps too. Then I realized what it means to look nice from a sales/marketing perspective. It is one thing if India is the sole purchaser, but if HAL wants to find an export market, they better find some good PR people.

[Carl_T]

Why does their PR really matter? If anything, we would want everyone to think it's crap and underestimate it, until they find out to their own peril!!!!
Although it wouldn't do anything for deterrence.

Wickberg does have a point though. I used to be one of those "who cares what it looks like as long as it works" type chaps too. Then I realized what it means to look nice from a sales/marketing perspective. It is one thing if India is the sole purchaser, but if HAL wants to find an export market, they better find some good PR people.

That is very true, since our costs are cheaper than other countries, we could be a big exporter of this birdie.

[Brando]

^^ India and DRDO don't even have a lick of a chance when you take the Chinese and their attempts to peddle their fighters!
Compared to the Chinese brand power and their industrial base, the LCA is still an expensive and risky proposition for foreign customers who don't have any idea of what Indian standards are and what Indian products are like!

India doesn't have any "quality" brand power to break through the first impressions. While the Chinese sell everything from poison to milk powder ( ) all over the world and people have a rough idea of "Chinese" quality!

[Brando]

It is a High-tech firm and they don´t even have a decent web page to present their products. Even a 13 year old Swedish bimbo would have a blog page that is more presentable then HALs. And the Indian air force, don´t they care about their image to the public? Where are theirs LCA page? For someone looking at this from the outside it seems very strange, Indians seems very nationalistic but when it comes to endorsing their own products you get the feeling they are ashamed of them and trying to do anything to sabotage it...

I've noticed this too when I've traveled to India! Shockingly Indians design website for all and sundry in the West but their own websites are rudimentary at best! The Internet in India still hasn't really penetrated the local populace to take a central place in society like in the West! It is still something peripheral in their psyche. The folks at HAL spend billions on all kinds of things but they are loath to spend a few hundred dollars on a decent web page because most of the "decision makers" are out of synch with modern attitudes of people and consider "web pages" as equivalent to a glorified ad in the yellow pages! Not the interactive and innovative medium that the rest of world uses. Such cultural anachronisms are to be expected in a public company run by people who are just coming to grips with modern technology.

[Gaur]

------------

Come on! Why so touchy? I am sure his intentions were not wrong and he has a point. The PR aspect is abysmal. If such PR would haev been displayed by China, we would have been the first to ridicule it. Hell, even Pakistan Airforce has "much" better web site.

[Rahul M]

I think we can all agree on that the sign on the DefExpo must have been wrong. It is as simple as that. {figuring out a rough estimate for landing distance is still an interesting exercise for an enthusiast.} And please do not call me "sir", I am not your father and you are a moderator here, if some one should call anyone "sir" it would be me calling it to you. I know it is a polite thing to do .............{put it down to cultural divergence. in this case sir is just a more polite version of 'dude'}

Off the record I think it would have been great if we could reverse time 20-30 years. ........All these had basically the same requirements, .......

I see the MCA as a possible project where saab can join in as a partner. IIRC saab too had plans of a 5gen fighter which didn't take-off due to funding constraints. on HAL/ADA's side the MCA project is yet to start officially, perfect time for an outsider to make a pitch and walk into the project.

[Philip]

Yaas.The radius of action is what made a former AM caustic about at its capability,"point defence" only.Nevertheless,our hundreds of MIG-21s have to be replaced at lowest cost to meet the same role.We have larger aircraft for other roles.I am most sceptical about the LCA's naval version which I think should be scrapped unless a MK-2 version is developed in good time with improved capability.It will have a radius of action which will just be equal to an anti-ship missile of Klub/B'Mos class and being a single-engined aircraft will be a ttoal loss in the case of engine trouble.

[nrshah]

Well, LCA is often compared to another light weight fighter, the Gripen. The A/B/C/D version of that has a combat radius of 800 km, the Gripen NG have one that is +1300 km. So compared to those numbers 300 km seems a bit strange....

Is combat radius of 800 Kms of Gripen A/B/C/D with drop tanks or internal fuel only?

I remember in this thread some mentioning AM quoting range of LCA is only slightly less than Mirage 2000...

[vipins]

I was searching for LCA range details in the sea of info(thanx to rakall ,k prasad , K Mehta n others gurus ) in the archived AeroIndia 2009 thread.Found a post where lots of links were posted by K Prasad saar but some links related to LCA details are not working now.Can anyone point to the correct link??
Here is the post link

There is quoted part of mehta ji's post in it which says

K Mehta wrote:
Post Link(this link is also not working now)
Info-relay from K prasad
Confirmed from CEMILAC director
LCA tested upto
1.6 mach
1354 Km
6g
22 AoA
more AoA after anti-spin parachute is integrated

[pralay]

K Mehta wrote:
Post Link(this link is also not working now)
Info-relay from K prasad
Confirmed from CEMILAC director
LCA tested upto
1.6 mach
1354 Km
6g
22 AoA
more AoA after anti-spin parachute is integrated

1354km/hr is the Sea-level max speed demonstrated during goa trials.

[Cybaru]

Well, LCA is often compared to another light weight fighter, the Gripen. The A/B/C/D version of that has a combat radius of 800 km, the Gripen NG have one that is +1300 km. So compared to those numbers 300 km seems a bit strange....

Is combat radius of 800 Kms of Gripen A/B/C/D with drop tanks or internal fuel only?

I remember in this thread some mentioning AM quoting range of LCA is only slightly less than Mirage 2000...

Gripen carries 200KGS less fuel than LCA. There is no way that it can have a larger radius than LCA.

rafale has approx double the fuel by weight, but it is also twin engined. Range for all these types should be same or similar without external tanks.

Shalav had a good excel spreadsheet. maybe he can share that again with yall.

[Wickberg]

Gripen carries 200KGS less fuel than LCA. There is no way that it can have a larger radius than LCA.

rafale has approx double the fuel by weight, but it is also twin engined. Range for all these types should be same or similar without external tanks.

Shalav had a good excel spreadsheet. maybe he can share that again with yall.

Why not? They are two different fighters with two different designs. LCA is lighter then the Gripen ABCD and have a similar engine but its max speed is Mach 1.6 while Gripens is +Mach 2.0. By your logic that would be impossible. It´s two different fighters, that´s all.

And as I wrote earlier, the 800 km radius is with full combat load and one central fuel tank.

I would also like to apologize if I offended anyone when I was critical about the webpages about LCA on HAL or the Indian Air force. It was just the lack of information I was complaining about, not the air craft it self. To me it seems like the most natural thing to do to have a good web site where you present your future fighter. Not for potential export customers but mainly for the general public. I would guess that there are a lot of LCA-critics in India (just like there are critics in Sweden, USA, UK etc about their indigenous projects), this lack of information probably just fuels them.

[Wickberg]

I see the MCA as a possible project where saab can join in as a partner. IIRC saab too had plans of a 5gen fighter which didn't take-off due to funding constraints. on HAL/ADA's side the MCA project is yet to start officially, perfect time for an outsider to make a pitch and walk into the project.

SAAB has never seriously planned for a 5 gen fighter for the Swedish air force. They have however been contacted by both South Korea and Japan with a request to design a stealth fighter for them. At least one concept (twin engined) have been presented to the public but I don´t know how far these negotiations have reached. I think the reason why this happened in the first place was because of the PAK-FA a possible Chinese 5 gen. fighter and that USA refused to export F-22...

At the moment the next thing we will see coming out of the SAAB assembly line will probably be the joint Neuron UCAV.

[Cain Marko]

I remember in this thread some mentioning AM quoting range of LCA is only slightly less than Mirage 2000...

Makes ample sense - the Tejas should have a range of about 1800km on internal fuel even though its engines are more economical than those of the M2k (thus, a relatively poor range of ~ 1850km) because the M2k has a better fuel fraction. Now otoh, if the M2k had something like the AL-31 on it its range as well as TWR would have made it seriously scary for a single engined beast (not to mention the abnormally low wingloading).

Gripen carries 200KGS less fuel than LCA. There is no way that it can have a larger radius than LCA.

Umm, not entirely true. The lower fuel weight iirc is for the Gripen A, the C carries about 2400kg of internal fuel.

rafale has approx double the fuel by weight, but it is also twin engined. Range for all these types should be same or similar without external tanks.

I really don't think two vs. one engine makes so much difference to the range. It is the fuel fraction and the SFC that count. Again, the Mirage 2000 despite being single engined and excellent fuel fraction (0.42) had relatively low range thanks to the M53s. Otoh, the MiG-29A despite having a pretty poor fuel fraction (0.31) and two engines still had a somewhat comparable range (1500km+) on internal fuel. Additionally, the MiG-29K, Hornet and the Super Hornet all of which have similar fuel fractions as the Mirage 2000, have a better range (2000km+).

Shalav had a good excel spreadsheet. maybe he can share that again with yall.

Yeah, I do wish he posted a bit more, had a couple of questions for him.

Anyways, in the absence of betters, one has to make do - Thus, based on empty weight - internal fuel - fuel fraction, I think the Tejas should have v.good range (corroborating the comparison to the M2k).

Legacy fighters:

F-16 (blk50) - 8500kg - 3250kg - 0.38 Range on internal fuel only ~ 1800km
M-2K -> 7600kg - 3250kg - 0.42, Range ~ 1850 km (poor SFC of the M53 engine)
MiG-29K -> 12400kg - 5000kg - 0.41, Range ~ 2000km
SU-30MKI -> 18400kg? - 10000kg - 0.54 (probly more). Range ~ 3000km
F-18E/F /-> 13900kg - 6500kg - 0.46. Range ~ 2200km
F-18 -> 10800kg - 4900kg - 0.43. Range ~ 2000km

RafaleM - 10000kg - 4800kg - 0.48. Range ~ > 2100km (with 2 wingtip Micas, should be more though)
Gripen C - 6500kg - 2400kg - 0.36. Range ~ 1750km (the NG is 40% more @ 2500km)
Tejas - 6300kg - 2400kg - 0.38. Range ~ 1800km.*
Gripen NG - 7000kg - 3350kg - 0.47. Range ~ 2500km?

So what we see is, SFC being somewhat similar, a fuel fraction of 0.40 leads to a range of ~ 2000km, 0.45-0.50 ~ 2200-500km, 0.55 ~ 3000km.

* If the empty weight of the Tejas is ~ 5600 (as per the poster board), then the fuel fraction ~ 0.42 and the range would correspondingly increase to ~ 2000km. Better engine SFC via either the 414s or the EJ-200 (esp. the latter) might also increase the range somewhat.

JMT.

CM

[Vivek K]

Why not? They are two different fighters with two different designs. LCA is lighter then the Gripen ABCD and have a similar engine but its max speed is Mach 1.6 while Gripens is +Mach 2.0. By your logic that would be impossible. It´s two different fighters, that´s all.

And as I wrote earlier, the 800 km radius is with full combat load and one central fuel tank.

Point that needs to be checked - Is Mach 1.6 the max speed or the max "demonstrated speed"?

Also since the LCA weighs less, and engines are same, wouldn't the SFC would be same for a given speed (or does the different aerodynamic drag cause a difference in SFC)? Is DRDO worried about the structural integrity (due to untested flight envelope) at higher speeds or is the airframe design, as insinuated by Wickberg, incapable of higher speeds due to greater drag? I would expect the former (ie untested envelope) and since open source info is delayed by 6-9 months the aircraft could have higher max speeds that have not been disclosed yet.

[Wickberg]

Now that is the real collaboration opportunity. I'm still hoping either the Tiffy or the Gripen will open the door for India to gain from the Neuron project. If the Babus can wake up to this golden opportunity, we might just have a decent twin-engined a/c and a part to play in the next Stealth UCAV project.

But IIRC the Typhoon is mostly a British project (at least the exports of it) while the Neuron is more of a French/Swedish project. So buying the Typhoon would´nt really help to open doors to the Neuron. Rafale or the Gripen on the other hand...

[Cain Marko]

CM, the nose diameter is 650mm..unless you manage to push the antenna really far behind (and that is difficult on the LCA because there is very little space behind the radome) you won't be able to fit a 650mm antenna itself. My guess would be a 600-625 mm antenna diameter depending on how much the size of the back-end instruments will be.

Kartik, I think Harry mentioned a 650mm antenna (at least the on the test/proto MMR) in the Radiance article. Perhaps, the production version would be smaller? Any reasons for this? In any case, 650mm nose diameter is still v.big for something that small. This is equal to a Mirage 2000 nose cone. A 600-625mm antenna would be >= F-16, Mirage 2000, J10. And definitely > Jf-17, MiG-21, Rafale. No wonder the MMR can detect 2msq birds @ 100km - v.decent and is similar to the Apg68 (V9).

Here is a relevant post by "Swerve" (PaulJI @ BR) re. the Grifo/Selex AESA via AFM -

I wonder what the 500E dimensions are?
From the Grifo brochure, antenna dimensions are
-
2000/16 - 74 x 48 cm (F-16)
S7 - 60 cm round
M3 - 47 cm (Mirage III)
M5 & S5 - 51 cm (Mirage V)
F1 & S1 - 51 cm (Mirage F.1)

F - 56 x 37 cm (F-5E)
L - 56 x 37 cm (L-159)

7 - 35 cm round (F-7)

I suspect they'd need more power for AESA upgrades, except perhaps the S-series.

IIRC, the 850E is sized for the F-16, same as the Grifo 2000/16.

Going by those figures, perhaps an 850TRM AESA is feasible on the Tejas?

CM.

[Rahul M]

vivek, off-hand, it will have somewhat higher drag because it is designed to be a more maneuverable platform, have a look at that insanely low wing loading. all that wing area translates to a higher drag unfortunately, nature doesn't allow you to have it both ways.

that said, the difference won't be that large, within 10-15% at most, probably less. secondly, don't discount our weather/environment conditions, the gripen's performance figures will also suffer a hit in the hot and high conditions. factor that in as well.

now, we have two datapoints by which to gauge range performance,
one a comment by a test-pilot that range was a little less than the mirage-2000
and reports of flights from b'lore to rajasthan (>1500 km away) for weapons trials. the loadout was 2 800l tanks + bomb racks + litening pods as we saw from the pics.


as for max speed, IIRC 1.6M is for IOC and 1.8M for FOC.

[Vivek K]

Thanks Rahul.