LCA News and Discussions, 22-Oct-2013

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Re: LCA News and Discussions, 22-Oct-2013

Postby dinesh_kimar » 12 Feb 2014 20:45

It is extremely fortunate that Thangavelu asked AK Anthony abt LCA Programme cost. I also was not knowing this figure.

For abt 8500 crores, India got FBW Technology, Glass Cockpit, Composite Air Frames, Sys Integration Skills, Started a Vendor Base, got Production facility for 8 /year, plus 15 prototypes.

Very good Value For Money, IMHO.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Indranil » 12 Feb 2014 20:55

Chacko sahab range of LCA is 500 kms without in flight refueling.

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Re: LCA News and Discussions, 22-Oct-2013

Postby NRao » 12 Feb 2014 20:58

They need to weave exports into all this. Will not be easy, but is essential.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Rahul M » 12 Feb 2014 22:27

indranil, range (one way) or combat radius (to and back) ? LCA TPs have commented that its range is very similar to mirage-2000's, which is around 2000 km.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Indranil » 12 Feb 2014 23:26

Sorry I meant combat radius. Range is about 1700 kms.

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Re: LCA News and Discussions, 22-Oct-2013

Postby gnair » 12 Feb 2014 23:32

So what's the consensus gentlemen?
The significance of range would be for basing. For Outbound traffic: Home/Squad base to Fwd. bases in theatre and the transit time taken to get there, or viz. for Inbound traffic, post action.
Where as the significance of Operational Radius would be the 'business end' of it's capability. And operational radius usually has an inbuilt 15 minutes of game time in the hot zone, with allowances for multiple short burst afterburner time, before egress.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Akshay Kapoor » 12 Feb 2014 23:35

The number going around is a combat radius of between 350 to 400 kms. LCA's fuel fraction on empty + fuel is about 27% ( 2450/9000). Mig 21 is similar. Mirage 2000 is around 35% I think. With full fuel and 1 ton payload Mirage 2000 has a combat radius of about 1400 km.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Rahul M » 12 Feb 2014 23:45

35% ? I am getting ~ 20% for M2k. 2880kg fuel and 13800kg loaded wt.

LCA loaded wt is nearer 10t than 9 IIRC.

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Re: LCA News and Discussions, 22-Oct-2013

Postby chackojoseph » 13 Feb 2014 07:39

Rahul M wrote:add the fact that the mig-27 flies on an outdated fuel guzzling turbojet, I really don't see how tejas would have a combat ratio any less than that of the flogger, let alone half of it.


MiG-27 is a simple aircraft for ground attack. Tejas has more powerful engines and electronics which are fuel guzzling. MK I combat radius is 300 - 350. MK II has higher fuel requirements and will give incremental increase in range. I do not see more than 25% increase in range vis Mk I.

Anyway, real calculations will come after they take MK II for a spin with entire loads and see how much weapon load drag reduces range.

As I said in the fist post on this topic, it is closer to half of MiG-27. it could be little more than half or less than half.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Viv S » 13 Feb 2014 08:04

chackojoseph wrote:MiG-27 is a simple aircraft for ground attack. Tejas has more powerful engines and electronics which are fuel guzzling. MK I combat radius is 300 - 350. MK II has higher fuel requirements and will give incremental increase in range. I do not see more than 25% increase in range vis Mk I.


The MiG-27 is a heavier, considerably draggier design. And the R-29 is a lot more powerful, though being a turbojet, its SFC is bound to be atrocious. There is no way it can match the Tejas' combat range.

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Re: LCA News and Discussions, 22-Oct-2013

Postby dinesha » 13 Feb 2014 08:29

Image

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Re: LCA News and Discussions, 22-Oct-2013

Postby Rahul M » 13 Feb 2014 09:07

no chacko, LCA's turbofan is not fuel guzzling in comparison to the flogger's old gen turbojet.

here's vivek's analysis of LCA range and combat radius, scroll down for the graphics.
http://mach-five.blogspot.in/search?q=lca

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Re: LCA News and Discussions, 22-Oct-2013

Postby sivab » 13 Feb 2014 09:29

Official numbers, without IFR.

http://pib.nic.in/newsite/erelease.aspx?relid=102056

LCA Tejas is capable of flying non- stop to destinations over 1700 km away (Ferry Range). It's Radius of Action is upto 500 km depending upon the nature and duration of actual combat.

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Re: LCA News and Discussions, 22-Oct-2013

Postby chackojoseph » 13 Feb 2014 10:22

sivab link shows official range 'depending'

If the Mig-27 has 750 advertised range and LCA has 500, then lca has lesser ranges for ground attack roles compared to MiG-27.

RahulM and the poster before,

Avionics eat up most of the power in the aircraft. LCA is avionics intensive.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Singha » 13 Feb 2014 10:27

Mig27 to my knowledge is used by iaf for 200km strike sorties. A 750k dpsa role is news to me.
did the soviet frontal av need all that range to hunt nato units?

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Re: LCA News and Discussions, 22-Oct-2013

Postby Rahul M » 13 Feb 2014 11:34

the750km figure appears only in one unref'ed instance in wiki. which is firmly DPSA category. if the mig-27 itself was capable of DPSA neither IAF nor RuAF would have opted for dedicated DPSA platforms. (su-24 or jaguar)

even the su-24 is advertised as

Operational radius of action at sea level in mixed mode (Vcr in the 200-km area, V=900 km/h in other areas) with PTB external fuel tanks and 6x FAB -500M-62 bombs, 615 km

I don't see how the shorter legged flogger has a combat radius of 750km.

chacko, avionics power consumption dictates fighter range to any significant figure ??? I don't see how, power consumption in fighters is in the range of 10-20 kW i.e 15-30 hp approx. max AFAIK.
that is a rather insignificant fraction of the power generated by jet engines.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Eric Leiderman » 13 Feb 2014 11:41

Unless the EW suite is huge like a growler the aux power including electronics/hydraulics etc will be not more than 50-80kw which is insignifigant in relation to total power

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Re: LCA News and Discussions, 22-Oct-2013

Postby Yogi_G » 13 Feb 2014 11:50

With an AESA the LCA should be consuming far less power on top of that with no moving parts. Some time back there was talk of progression towards SoC avionics by DRDO. I am assuming a lot of the redundancy enabled systems will already be SoC so these add to the power efficiency.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Akshay Kapoor » 13 Feb 2014 16:44

Hi Rahul M,

I stand corrected. M2K C empty weight is around 7500 k and internal fuel is 3160 (mirage - jet .net website and a couple of others). M2K H should not be too different. Taking 7500 empty and 3100 k internal fuel I get fuel fraction of 29.2 (3100/7500+3100). I think the 35 number stuck in my mind from a converstaion I had with an old fighter pilot friend a long time ago and when I looked at wiki I saw 7500 empty and 13800 loaded so thought it should have around 6 tons internal fuel and 35% made sense.

I dont think the loaded weight calculations of M2K are correct on wiki. Even if you add lubricants and empty pylons and pilot weight. You should not get above 11 tons. Maybe they are refering to a full comabt load. With Tejas, empty 6500 + fuel 2500 = 9000. Add lubricants and pylons and you get 500 kg more which is 9.5 tons loaded weight.

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Re: LCA News and Discussions, 22-Oct-2013

Postby chackojoseph » 13 Feb 2014 19:12

Rahul M,

I will try to get the MiG-27 figures or Rahul Devnath might be of help. Extremely busy with books. Navy book is close to printing. DRDO Missile book is in fast pace. I will revert with actual figures when possible.

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Re: LCA News and Discussions, 22-Oct-2013

Postby SaiK » 13 Feb 2014 20:11

http://bharat-rakshak.com/NEWS/newsrf.php?newsid=20805
shame on ak sahib to not up the ante on kaveri. shame !

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Re: LCA News and Discussions, 22-Oct-2013

Postby vivek_ahuja » 13 Feb 2014 21:39

Rahul M wrote:the750km figure appears only in one unref'ed instance in wiki. which is firmly DPSA category. if the mig-27 itself was capable of DPSA neither IAF nor RuAF would have opted for dedicated DPSA platforms. (su-24 or jaguar)

even the su-24 is advertised as

Operational radius of action at sea level in mixed mode (Vcr in the 200-km area, V=900 km/h in other areas) with PTB external fuel tanks and 6x FAB -500M-62 bombs, 615 km

I don't see how the shorter legged flogger has a combat radius of 750km..


Folks very easily confuse combat radius with range (one way). Companies making these brochures like to put out one-way range data in ambiguous terms just for this reason. So it helps stir a conversation where combat radius of one aircraft is being compared with the one-way range of another aircraft and people are crying bloody-murder.

To further exacerbate issues, people take the one-way range of the aircraft, assume it to be the radius and then double that to say: "oh look, here's the 'true' range of this bird!" :wink:

For the Mig-27, the 750km is the range on internal fuel, one way at low-medium altitudes (my own analysis shows somewhere around ~800km range). Combat radius is around ~250km assuming maneuvers and fuel burnt on afterburners inside the combat zone.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Rahul M » 13 Feb 2014 22:39

that's more like it. thx vivek.

Kapoor sahab, I agree the 13.8 t figure looks too high. .29 is in the correct ballpark.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Lalmohan » 13 Feb 2014 23:21

250km is about right, s'why you see almost everyone carrying drop tanks and/or refueling mid air

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Re: LCA News and Discussions, 22-Oct-2013

Postby gnair » 13 Feb 2014 23:56

sivab wrote:Avionics eat up most of the power in the aircraft. LCA is avionics intensive.
sivab link shows official range 'depending'


Slight digression from the range/endurance topic;
I need to confirm this with someone, but I am not sure if electrical power consumption is a drag on engine power. Electricals are through engine ancilaries (akin to a car with or without headlights have no bearing on engine power, provided the alternator does its required job as per spec.) Like wise the F-404's generator should cover all electricals in slave mode, without sucking any more or any less from the engine. But pneumatics, including pressurization, de-icing boots and such have an impact on thrust and it's compensated either by flying at a lower pressure altitude or throttle fingering resulting in higher fuel burn and impacting endurance. In totality, it's not significant as pneumatics are not typically operated for more than 5-10 minutes at a time.

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Re: LCA News and Discussions, 22-Oct-2013

Postby vivek_ahuja » 14 Feb 2014 02:43

Rahul M wrote:that's more like it. thx vivek.


Additionally, I should mention that a similar first order analysis for the LCA yields a range (one-way) of ~1550 km (give or take) assuming only internal fuel of (2500 kg) at 10,000 feet at Mach 0.6 (measured at sea level). This Mach 0.6 requirement in cruise stems from the need to carry only internal fuel and empty weight of the aircraft, i.e. no external fuel tanks.

So for the above flight profile setup, the combat radius comes out to ~700 km.

But this carries no payload and or fuel tanks. Fuel tanks will increase range. Payload and external tanks will increase drag and reduce range. I will try and put up some numbers for that later when I get some time to model the tanks underneath the wings (been wanting to do that for some time but this argument about the LCA range has finally sent me over the deep end 8) ).

Edit: So the addition of two external drop tanks provides an increment of about 33% in drag at the benefit of additional ~1900 kg of fuel. This amounts to about ~2000 km ferry range. Assuming that there is significant burnoff of fuel during climb and recovery, the 1700 km ferry range quoted by the document listed above makes sense.
Last edited by vivek_ahuja on 14 Feb 2014 04:34, edited 1 time in total.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Akshay Kapoor » 14 Feb 2014 03:26

Hi Vivek,

How did you arrive at the radius? We know the fuel fraction, and the internal fuel. So we have to find some way of calculating fuel consumption right? I tried to play around with the engine's fuel consumption figures but wasnt sure how to model them. It said 86 k/kilo newton/hour. So that means in an hour at 56 KN dry thrust we are talking over 4 tons of fuel? What am I missing? Can you show us simple minded chaps how it works?

Also how much would the radius be with 1 ton of bombs and 2 missiles and only internal fuel?

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Re: LCA News and Discussions, 22-Oct-2013

Postby vivek_ahuja » 14 Feb 2014 03:44

Akshay Kapoor wrote:How did you arrive at the radius? We know the fuel fraction, and the internal fuel. So we have to find some way of calculating fuel consumption right? I tried to play around with the engine's fuel consumption figures but wasnt sure how to model them. It said 86 k/kilo newton/hour. So that means in an hour at 56 KN dry thrust we are talking over 4 tons of fuel? What am I missing? Can you show us simple minded chaps how it works?


So the essence of the modeling is based on determining the performance of the cranked-delta wing for lift and drag. Despite the presence of the fuselage in there, you will be surprised how much can be accomplished by first order aerodynamic modeling of the wings. That too about the mean-camber surface onlee.

I was able to get a good three-view of the LCA on google. Took a printout, measured the dimensions and extracted the following surface representative of the LCA wing performance:
Image

Then, I retessellated this surface and solved for the surface vorticity and the shed vorticity to yield the following (at 5Deg AOA).
Image

Bottom line is that you determine what the flight characteristics needs to be to lift X kg of mass of the aircraft at a certain altitude and corresponding atmospheric conditions. If you know the CL-AOA behavior of the wing, the minimum required Mach number in cruise is determined. For the present case, at 10,000 feet AGL, the required Mach number for cruise without payload or tanks comes out to Mach 0.6. This is then used to evaluate the net drag on the fuselage. Again, modeling the induced-drag profile of the mean-camber wing plus a Reynolds number based skin-friction drag model gives you representative CDi and CDo values. The sum of these parameters (plus correction factors for additional drag from fuselage and empennages) gives you a net cruise drag coefficient. Multiply this by the dynamic pressure using the Mach 0.6 conditions and you will get the net required thrust to maintain this constant speed.

For the present case, the required thrust came out to ~0.29 Kg/sec for the LCA, which is below what you get assuming full thrust from engine (~1.232 Kg/sec). The reason for this is that the entire engine thrust is not needed for balancing drag at higher altitudes and moderate speeds. Same reason why all aircraft perform better the higher they climb for the cruise part of their flight.

Knowing the fuel consumption and the cruise Mach number (measured relative to Sea-Level atmospheric conditions) provides you with the ability to calculate how far the aircraft can go if it went in a straight line.

For the LCA, this came out to be ~1550 km as stated previously.

Note that this is all a first order analysis, of course, and only meant to be a sanity check on performance. I used to teach such relatively simple (back of the envelope) methods to students as a way to bypass the complexity of full-up computational methods when quick analysis is required.

Also how much would the radius be with 1 ton of bombs and 2 missiles and only internal fuel?


Let me crunch some numbers and get back to you on that one.

Add about 30% on drag increment for the external payload on this one (~8% each for one large bomb plus pylon effects). The range is then reduced to around ~1190 km. Combat radius is reduced to around ~500 km or less.
Last edited by vivek_ahuja on 14 Feb 2014 04:36, edited 1 time in total.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Indranil » 14 Feb 2014 04:02

Come on guys. What is this talk about avionics drawing most of an aircraft's power?

When a clean LCA is flying level and at a constant speed of 720 kmph, the power requirement from the engine is of the order of 0.5 - 0.8 Megawatt! When the LCA is flying with full AB (90 kN) at 1600 kmph, the engine is generating power at the rate of 90 * 1600000/3600 kW = 4 Megawatt!

This is simple physics!

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Re: LCA News and Discussions, 22-Oct-2013

Postby chackojoseph » 14 Feb 2014 06:32

Indranil, you should read the very first mention of this issue rather than pulling some parts.

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Re: LCA News and Discussions, 22-Oct-2013

Postby chackojoseph » 14 Feb 2014 07:43

vivek_ahuja wrote:Folks very easily confuse combat radius with range (one way). Companies making these brochures like to put out one-way range data in ambiguous terms just for this reason. So it helps stir a conversation where combat radius of one aircraft is being compared with the one-way range of another aircraft and people are crying bloody-murder.

To further exacerbate issues, people take the one-way range of the aircraft, assume it to be the radius and then double that to say: "oh look, here's the 'true' range of this bird!" :wink:

For the Mig-27, the 750km is the range on internal fuel, one way at low-medium altitudes (my own analysis shows somewhere around ~800km range). Combat radius is around ~250km assuming maneuvers and fuel burnt on afterburners inside the combat zone.


Absolute bouncer for me. With respects though.

Can you please explain to me "For the Mig-27, the 750km is the range on internal fuel, one way at low-medium altitudes (my own analysis shows somewhere around ~800km range)." I have no understood what is meant by that.

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Re: LCA News and Discussions, 22-Oct-2013

Postby vivek_ahuja » 14 Feb 2014 07:50

chackojoseph wrote:Absolute bouncer for me. With respects though.

Can you please explain to me "For the Mig-27, the 750km is the range on internal fuel, one way at low-medium altitudes (my own analysis shows somewhere around ~800km range)." I have no understood what is meant by that.


Oops. I hope that was not taken the wrong way. The "folks" I referred to in my comment was not you. But I can see how the words could be read that way. Apologies.

That said, I stick by my assertion and my analysis that the 750 km range is for the internal ferry range of the Mig-27 at ~10,000 feet AGL. I honestly cannot come up with any reasonable numbers that suggest otherwise.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Singha » 14 Feb 2014 08:03

the basing of the Mig-27 in really fwd bases like hashimara, Bhuj, halwara,jodhpur, indicates nature of its radius and tactical mission also. none are deep like gwalior, bareilly or pune.

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Re: LCA News and Discussions, 22-Oct-2013

Postby chackojoseph » 14 Feb 2014 08:06

vivek_ahuja wrote:Oops. I hope that was not taken the wrong way. The "folks" I referred to in my comment was not you. But I can see how the words could be read that way. Apologies.

That said, I stick by my assertion and my analysis that the 750 km range is for the internal ferry range of the Mig-27 at ~10,000 feet AGL. I honestly cannot come up with any reasonable numbers that suggest otherwise.


Actually I did not read the 'folks' part and its ok to use.


Lets standardize the discussion with clean ranges instead of complicating it.

As per open sources for MiG-27 http://wiki.scramble.nl/index.php/Mikoy ... ich_MiG-27
-low level 1080 km
-optimum height 2100 km

10,000 ft is not really a low altitude.

This is my counter point to arrive at a solution than a shouting match. What is the LCA figures for 10,000 ft altitude?

Singha,

Its to do with existing fields from Raj. Better indicator will be Iraqi employment vis Iran, if we have a narration.

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Re: LCA News and Discussions, 22-Oct-2013

Postby vivek_ahuja » 14 Feb 2014 08:16

chackojoseph wrote:As per open sources for MiG-27 http://wiki.scramble.nl/index.php/Mikoy ... ich_MiG-27
-low level 1080 km
-optimum height 2100 km


So here's my argument: Because these open sources do not cite the configuration used to reach that range (externals tanks? If so, how many? Or was it internal fuel only? Weapons carried? Altitude? Speed? etc.), my assertion is that they confuse ranges meant for different configurations and heights and extrapolate from it without realizing it. Naturally, if the Mig-27 carried some drop tanks, I am sure the 1080 km range might be feasible. But they don't state that configuration and assume that it must be internal fuel only.

chackojoseph wrote:10,000 ft is not really a low altitude.


Which is why I said low-medium. The point being that 10,000 feet is measured from sea level conditions. I should have said ASL instead of AGL. My mistake. However, the point is that for aircraft performance, altitudes above 15,000 feet become high.

chackojoseph wrote:This is my counter point to arrive at a solution than a shouting match. What is the LCA figures for 10,000 ft altitude?


I will quote my previous response on this matter here. This comparison was made for the same 10,000 feet ASL altitude:

vivek_ahuja wrote:Additionally, I should mention that a similar first order analysis for the LCA yields a range (one-way) of ~1550 km (give or take) assuming only internal fuel of (2500 kg) at 10,000 feet at Mach 0.6 (measured at sea level). This Mach 0.6 requirement in cruise stems from the need to carry only internal fuel and empty weight of the aircraft, i.e. no external fuel tanks.

So for the above flight profile setup, the combat radius comes out to ~700 km.

But this carries no payload and or fuel tanks. Fuel tanks will increase range. Payload and external tanks will increase drag and reduce range. I will try and put up some numbers for that later when I get some time to model the tanks underneath the wings).

Edit: So the addition of two external drop tanks provides an increment of about 33% in drag at the benefit of additional ~1900 kg of fuel. This amounts to about ~2000 km ferry range. Assuming that there is significant burnoff of fuel during climb and recovery, the 1700 km ferry range quoted by the document listed above makes sense.


Also, I will quote the following for a combat configuration:

vivek_ahuja wrote:Add about 30% on drag increment for the external payload on this one (~8% each for one large bomb plus pylon effects). The range is then reduced to around ~1190 km. Combat radius is reduced to around ~500 km or less.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Singha » 14 Feb 2014 08:21

Tejas is slated to quality the sleeker & smaller capacity M2K style supersonic drop tanks before FOC iirc. this will change your drag eqn - reduce drag but decline in addl fuel as well. might be more effective from a combat pov.

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Re: LCA News and Discussions, 22-Oct-2013

Postby chackojoseph » 14 Feb 2014 08:39

The figure with drop tanks and clean are also available. So there is no confusion.

http://en.wikipedia.org/wiki/Mikoyan-Gu ... ogger-K.29

540 km (290 nmi; 340 mi) (with two Kh-29 ASMs and three drop tanks lo-lo-lo) [2]
225 km (120 nmi; 140 mi) (with two Kh-29 ASMs and no external fuel) [2]

I request you and if its possible,

Can you calculate the range of lca with (kh-29 - approx 660 kg) 1320 weight at lo-lo-lo situation. But, we have to use ratios to bring common figures for both aircraft's. Both with 3 drop tanks and with only internal fuel.

* This is only a theoretical exercise. Each aircraft is purpose built and has a specific flight profile to be used. Our original discussion is if LCA can be a replacement based on range which MiG-27 used to provide for IAF.

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Re: LCA News and Discussions, 22-Oct-2013

Postby vivek_ahuja » 14 Feb 2014 08:44

chackojoseph wrote:The figure with drop tanks and clean are also available. So there is no confusion.

http://en.wikipedia.org/wiki/Mikoyan-Gu ... ogger-K.29

540 km (290 nmi; 340 mi) (with two Kh-29 ASMs and three drop tanks lo-lo-lo) [2]
225 km (120 nmi; 140 mi) (with two Kh-29 ASMs and no external fuel) [2]


This 225 km radius is good to know. For the Mig-27, my previous analysis suggested the same:
vivek_ahuja wrote: Combat radius is around ~250km assuming maneuvers and fuel burnt on afterburners inside the combat zone.


chackojoseph wrote:I request you and if its possible,

Can you calculate the range of lca with (kh-29 - approx 660 kg) 1320 weight at lo-lo-lo situation. But, we have to use ratios to bring common figures for both aircraft's. Both with 3 drop tanks and with only internal fuel.


Okay. I will post some numbers in the morning when I have access to the software. Question: what quantity tanks do the IAF Mig-27s carry? Do you have any data on this?

chackojoseph
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Re: LCA News and Discussions, 22-Oct-2013

Postby chackojoseph » 14 Feb 2014 08:57

I suppose they carry PTB-800, meaning 800 ltr tank.

And please add Jaguar too into analysis.

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Re: LCA News and Discussions, 22-Oct-2013

Postby Singha » 14 Feb 2014 09:54

Mig-27 carries a huge cannon. nothing else in IAF has that throw weight. but to use it, comes well within the MANPAD bubble.


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