LCA: News & Discussions - October 2016

[nachiket]

My point was limited - If there is an issue with any aspect of a program, or likely to be an issue, there are very convenient arguments created on the fly. And then we've the favorite of all buzzwords, iterative development, thrown about.

Iterative development is not a buzzword. That is how many complex defence projects are run, especially fighters. We have the Rafale, EF, Gripen etc. as examples.

If there is likely to be an issue or an issue - 'Who needs a gun, anyway? IAF is an idiot to ask for a gun in the first place in 21st Century!

These are definitely ridiculous statements. Who said them?

Didn't IAF import Mig-21 in 60s w/o guns. Even F-35 did not have gun ready at IOC...'

Don't know who said these but both statements are factually correct.

How about - 'Hmmm something seems to have gone wrong. Things did not pan about as we expected. Need to have a re-look'
There is a fundamental difference in the above two approaches.

This is how any actual r&d team would react. Including the LCA team. Refer to the radome issue for e.g. Isn't this exactly what happened? Of course in a critical program like the LCA you also need to consider whether whatever problem you are facing should stall the project completely till it is fixed or if initial acquisition and operation can go ahead while the issue is resolved in parallel.

[Indranil]

Akshay sir, with all due respect (and I say that with utmost sincerity to anybody who has served), I would like your inputs on the following:

1. Would you agree that the derision of an average scientist/engineer in the defense sector in the forces, media or public in general is much higher than that of an average soldier? If yes, is it fair only because one does not wear an uniform?
2. Do you think a soldier derided in public, devoid of his arms would be motivated to fight every morning to work. If not, why would a scientist/engineer?
3. Do you think passing the buck of every late/bad decision to the nameless babu, politician, scientist or engineer is the "balanced" viewpoint?

Please trust me, I am not trying to change your opinions, thoughts, or show you mirror, and all that non-sense. I am asking this questions because I feel the same way for my brother engineers/scientists as you feel for your brother soldiers. It doesn't mean that I disrespect the men and women who guard my family.

[srai]

Indranil, great news on the supersonic drop tank. Found a paper on the studies conducted for the supersonic drop tank on the Tejas



Centerline supersonic drop tank - looks like the LCA AF Mk2 variant, looking at the plug just aft of the cockpit. The paper dates back to 2015, around the time that studies to modify the geometry of the LCA AF Mk2 canopy geometry were just about done. Perhaps that may explain why the canopy geometry in the picture I posted above reflect the pre-area ruling studies optimization.

This is the tank which is ready now. I am a little exasperated with the guys developing the tanks. Seriously, is this much amount time required to come up with a tank?

P.S. added later. My information may be dated. I think I knew that the 450 ltr tank is ready. But after reading this paper, I think I am not correctly informed on this. But, I still think that the "tank" guys are letting the perfect be the enemy of the good.

Is the Supersonic tank only in the centerline pylon? An external tank that size would be good fit for mid-wing pylons, which would free up space for heavier weapon loads to be carried in the innermost wing pylons.

[srai]

Here are the likely twin-pylon configurations for the Tejas Mk2- and hopefully will be retrofitted to the Tejas Mk1A and Mk1 as well. If the wing needed strengthening to carry the additional weight on the outboard hardpoints, this configuration may not be seen on the Mk1.

CCM + SPJ
CCM + CCM on the outermost pylons

Kartik, these studies are for MK1A ( to be retrofitted on the Mk1). The outboard pylon is strong enough to carry the load. I have had long discussions with paan waalas on this. On Mk2, they will go for internal SPJ.

I initially thought they might do it more like this in the inner pylons.

[srai]

Speaking about multi-rack, this one is pretty insane-4 of them.

[Karan M]

Kartik, these studies are for MK1A ( to be retrofitted on the Mk1). The outboard pylon is strong enough to carry the load. I have had long discussions with paan waalas on this. On Mk2, they will go for internal SPJ.

Do you know why the SPJ here has such blunt nose..??

Jay, its an ELTA EL/L-8222 with the radome in the front. See:
http://www.iai.co.il/sip_storage/files/7/27537.pdf

[Karan M]

They are not prioritizing multi-rack BVR carriage as it is difficult to envision a scenario where a light fighter has not entered close combat even after firing two BVRs.

That is a serious mistake (IMHO) on their part given the issues with per missile reliability for most worldclass missiles and the need to launch multiple missiles per target for decent Pk.

[Indranil]

Srai sahab,

This particular tank is optimized for the center pylon. I think they might design tanks for wings as well. But that will be for longer endurance, not more loads. There's a point much below MTOW, beyond which the engine cannot accelerate the aircraft to supersonic speeds.

[Karan M]

Sounds good on paper, but typically doesn't go that way in typical aerial combats. That's why ASTE never even asked for it. People generally don't fire BVRs from more than 40 km away. Otherwise, your opponent has a very high chance of surviving and knowing where you are. In a 1:1, you may be able to turn the table and gain kinematic advantage while he maneuvers himself out of trouble, but then you would have entered or are about to enter close combat. You are now loaded with heavier, more expensive, and less numerous BVR missiles in a close combat situation. Your adversary might be able to turn the tables if he is flying light. So two BVRs are enough against a single adversary situation.

Depends on the missile and radar combination. I wouldn't be surprised if F-22s are clocking in 100km ranges for their AMRAAM shots and we achieve 60km+ for our Astras from fast Su-30s.

Now let's take 1:many situation. Firing multiple BVRs at multiple targets simultaneously is a radar capability that all manufacturers advertise. But, those are under test conditions. Imagine what would happen in a real combat. Let's say you fired at 4 BVRs at 2 targets. Those pilots are trained as well. They will break-away in opposite directions. Now, how far could you turn away and yet keep both aircraft in your radar cone? Eventually you will have to choose to follow one of them. Again, you will soon enter close combat with that pilot. Albeit, you will have a significant advantage. But, you have given his buddy a good chance of surviving. And while you turn on his mate, he turns on you, and he hasn't fired any missiles yet when you barely have enough to take down his mate.

SA is via AWACS or another fighter and shooters hence don't have to worry about losing track of individual targets for their specific nose cones.

Bottomline more BVR missiles is a necessity. Unless you are a stealthy F-35 and even there, more are planned.

In the A2A loadout, against similar opponents, it is almost always better to have a CCM:BVR ratio of more than 1:1. Especially, for lighter aircraft like LCA. So dual racks can come, but they are not the priority right now.

Completely disagree. The entire premise of having an AESA is to reach out and hit, and not engage in dogfights.

[Indranil]

There is always the possibility that they are considering it and I am misinformed. But I know that it is certainly not a priority item as of now. I also know that IAF hasn't asked for it either.

May be I am sitting with the wrong circle of friends, pilots included. But that 1:1 ratio is not from me. That is what most of them agree with. They do not believe in having most pylons taken over by BVR missiles and having nothing to fight with in close combat situations.

P.S. I do have friends who fly the latest 4.5 generation crafts, but none who fly the 5th. I don't know how the equations change there.

[srai]

They are not prioritizing multi-rack BVR carriage as it is difficult to envision a scenario where a light fighter has not entered close combat even after firing two BVRs.

That is a serious mistake (IMHO) on their part given the issues with per missile reliability for most worldclass missiles and the need to launch multiple missiles per target for decent Pk.

From what little I read about modern BVR tactics with active seeker missiles is the aircraft that detects an enemy first will increase speed, climb up and launch AAMs to give them best possible kinematics and then bank away to avoid any incoming missiles. That's where F-22 has advantage with its VLO and super-cruise. And then repeat that process until WVR occurs.

The other technique shown by Gripen is buddy BVR where one illuminates the target with its radar while the other shoots BVR silently from another location.

However, in all of wars fought till now BVR kills have occurred in 30-40km max ranges. Part of had to do with engagement policies adopted at those times. With the ranges of BVR missiles increasing to over 100km, we will likely see more long range shoot-offs (and probably less kill ratio per missile).

[srai]

Srai sahab,

This particular tank is optimized for the center pylon. I think they might design tanks for wings as well. But that will be for longer endurance, not more loads. There's a point much below MTOW, beyond which the engine cannot accelerate the aircraft to supersonic speeds.

Yes, agree. I was thinking from about it this type of load config where 450ltr-sized external tank on mid-wing would be good to have as an option.

[Kartik]

They are actively...? Your statement ended abruptly.

Stray sentence. Corrected it.

I cannot understand how they cannot envision such a scenario, especially when it lends so much more flexibility to the overall loadout. The 4 BVRAAMs would give the Mk1A the choice to avoid entering close combat, especially if they were to encounter a large enemy fighter package. Fire the BVRAAMs, and the AESA should be able to guide them while the Tejas Mk1A would be turning away. The AESA radar should be able to handle 4 targets simultaneously, right? Or is that a limitation they anticipate?

I'm assuming you're talking about the mid-board pylon being used for twin carriage of BVRAAMs? The twin racks would allow 4 Derby ER/Astra and 2 Python V to be carried with a centerline fuel tank, or inboard drop tanks, or a 1000 lb bomb or LGB. the paper indicated that the outboard hardpoint was being considered for twin CCMs, not BVRAAMs, perhaps due to the higher weight of BVRAAMs versus CCMs.

Sounds good on paper, but typically doesn't go that way in typical aerial combats. That's why ASTE never even asked for it. People generally don't fire BVRs from more than 40 km away. Otherwise, your opponent has a very high chance of surviving and knowing where you are. In a 1:1, you may be able to turn the table and gain kinematic advantage while he maneuvers himself out of trouble, but then you would have entered or are about to enter close combat. You are now loaded with heavier, more expensive, and less numerous BVR missiles in a close combat situation. Your adversary might be able to turn the tables if he is flying light. So two BVRs are enough against a single adversary situation.

Now let's take 1:many situation. Firing multiple BVRs at multiple targets simultaneously is a radar capability that all manufacturers advertise. But, those are under test conditions. Imagine what would happen in a real combat. Let's say you fired at 4 BVRs at 2 targets. Those pilots are trained as well. They will break-away in opposite directions. Now, how far could you turn away and yet keep both aircraft in your radar cone? Eventually you will have to choose to follow one of them. Again, you will soon enter close combat with that pilot. Albeit, you will have a significant advantage. But, you have given his buddy a good chance of surviving. And while you turn on his mate, he turns on you, and he hasn't fired any missiles yet when you barely have enough to take down his mate.

In the A2A loadout, against similar opponents, it is almost always better to have a CCM:BVR ratio of more than 1:1. Especially, for lighter aircraft like LCA. So dual racks can come, but they are not the priority right now.

I don't agree with the reasoning completely, and actually speaking, the twin racks on the mid-board pylon can be designed to accomodate BVR and CCM missiles, not just 2 BVR missiles only. If the reasoning is that 4 BVRAAMs is overkill or not ideal for close combat. What dual racks do is to allow for more missiles to be carried by any given fighter, which is a sort of factor of safety- the more missiles the fighter has to defend itself or attack other enemy jets, the better.

Also, the USAF and others are coming around to the reasoning that carrying a lot of BVR missiles may be essential, especially when going up against swarms of Chinese fighters. the IAF too may need to take on the PLAAF, and equipping your light fighters to be able to carry 4 BVRAAM and 4 CCMs or combinations thereof, in case the the need arises, seems prudent. the USAF is talking about quad pack racks for AMRAAMs on F-15s.

[Indranil]

Regarding USAF vs. Chinese fighters, it is difficult to say. Which of the two parties are on the longer flight stretch. That will dictate the tactics of engagement. Regarding taking on a swarm of Chinese fighters, many believe that given the quality advantage of both USAF aircraft and missiles over their Chinese counterparts, the former would do better to carry more missiles per aircraft to offset the numerical disadvantage vis-a-vis aircraft. This is also based on the fact that most modern aircraft (including the Chinese) won't be downed by BVR missiles at long range. The BVR missile puts them in a compromised position at the "merge", and the CCM will be used to finish off the job. As you might already know, even with fifth gen aircraft boasting x:1 killing ratio vis-a-vis fourth gen adversaries, it is derived out of on y sorties where y if typically >= x/2.

I agree with you that multi-racks gives more flexibility. When, I was even more aggressive while arguing with some folks. I asked why not cross pylons for 800 ltr DT+ 2 A2A missiles, twin A2A racks and twin CCM racks. I was calmly pointed to the fact that more missiles doesn't mean more effectiveness. There are drag penalties of each of those pylons. The British actually advertise that some of their aircraft can actually discard empty pylons in an emergency, returning to a clean config at that hardpoint.

Actually, if you look at the ones proposed for dual CCM carriage on the Mk1A, it is not a big change from the single rack solution. They have just turned the rail launcher by 90 degrees. So, if they feel the need, it should not be a big deal to come up with (at least an unoptimized) solution for the midboard station as well.

Personally for me, I would love to see more drag optimized pylons before multirack solutions.

[srai]

Regarding BVR tactics of the IAF, it went through major revisions post Ex-Garuda-1 in 2003.

viewtopic.php?t=333#p31547

...
3. The results have so far been mixed for the IAF. In the initial phase of the exercises, most of our Mirages were blown away by the French in BVR combat. IAF pilots tell me French tactics in the BVR regime are different and more flexible than ours. The high number of French kills prompted the IAF to review its exercise tactics at the end of the very first day of exercises ... and in the last few days the IAF has been claiming its share of kills. The IAF says it is more than a match for the French Air Force in WVR combat ... the French have also been impressed with our dog fighting skills. In the last couple of days ... following a change in our tactics, our pilots have been calling "Vic 1" ("Fox 1" for the French) announcing a R-530D launch at more or less the same time as the French. The missiles of both planes fly past each other ... the kill being "granted" on the basis of a detailed debrief at the end of the exercises.
...

viewtopic.php?t=333#p31556

...
"It is their international experience that we lack. Also, it is their ability to lock-in and fire from beyond visual range," says Squadron Leader N.K. Choudary. The Mirages of both air forces are loaded with similar weapon systems. ... But the advanced radar of the French allow them to fire at aerial targets from ranges upto 20 km.

"In close combat, we are generally better. But you need to get close enough to combat," says a flight lieutenant with the IAF's Tigers.
...

[brar_w]

The USAF interest in larger missile loads for its legacy fleet has actually evolved as it has gained experience operating the F-22 raptor. Given their experience of large force exercises over the last decade plus they value the situational awareness and the ability of the aircraft to penetrate and operate in areas where the older generation aircraft cannot. Interceptor like tactics of high altitude high speed have evolved to also include a healthy mix of FEBA penetration and concepts of being the sensor to a shooter much further back. Longer ranged BVR tactics have been enabled by better target discrimination via improved front end sensors as they have transitioned to AESA radars and better networking between forces and with the missiles in general.

Much like the threat of magazine shortage on the ABM side they are fearful of being overwhelmed in the future by things they themselves are wargaming with, developing and deploying such as decoys, micro swarms etc etc..this is leading to high magazine depth load out programs for both 5th and 4th generation aircraft such as the SACM to complement the traditional MRAAM as it evolves. The last BVR missile fired in anger in combat was a lot different from the modern AMRAAM-C7 or D and the Meteor in both capability and how it interfaces with much improved sensors of launch aircraft. CCM's are very important but there has been an intention to have envelope overalap as both types of missiles grow in capability going forward.

One would assume that as the IAF gets the Meteor, Derby-ER and Astra in large quantities to the Rafale, Su-30 and LCA fleets its tactics will also evolve to make best use of Active AAMs as a large force package. One on one scenarios are just about the most useless way to study air combat. Going forward standardizing on the Astra family will be pivotal. Reliable and capable active AAM's are a tremendous force multiplier and an often overlooked aspect of the AMRAAM program is its very large production quantity over the years (20,000+ produced over the years with over 1000 Aim-120Ds in current USAF and USN inventory) and the relatively large number of missiles frontline squadrons fire each year in Archer and other training deployments. For starters they have to resolve to standardize to one main BVRAAM for the next generation of fighters and wean off from imported types where the ability to tinker around and make changes is curtailed.

[Cain Marko]

Personally, I'd really like to see some recessed hard points on the mk2, if not the mk1A. As time passes, and we have longer ranged aams with better seekers and pks, the ability to carry fast and high will gain prominence. In time, ranging and tracking might happen at very long ranges with passive sensors. The trend is to move towards greater distances but with great kinematics... The Foxhound may stay in business for a long time to come.... Fast, high altitude and large number of missiles. The typhoon is another beast.

[srai]

One option for multi-carriage of weapons on a single pylon with good aerodynamics would be to use stealthy external pods.

[shiv]

As far as I can tell from general reading - there are 3 situations in which we might see aerial combat and the possible use of BVRAAMs or CCMs/guns

1. A strike formation with two offensive armed aircraft and two escorts
2. CAPs/ Scramble on alert for defence over our own airspace
3. US/NATO coalition style "denial of airspace/no fly zone" enforcement

I don't see the IAF getting into that no fly zone business anytime soon.

In the case of a strike formation over hostile airspace the purpose of the escort is to ensure that the attacking aircraft are able to carry out their mission. That means engaging hostile intercepting aircraft and drawing them away so the attackers can go and hit what they need to destroy. The ability to escort must come with the ability to detect hostile intercepting aircraft. It is entirely possible that an attacking formation of 4 aircraft simply detect a missile or missiles coming in from somewhere and not detect any defending interceptors at all. This situation will be factored into any attack planning by using various tactics which could include trying to keep the attackers low and stealthy and the escorts showing themselves as soon as a threat becomes evident. Also staged, serial multiple attacks on the same target to confuse/overwhelm defences. The idea for the AAM carrying escorts will be to persist and engage and scooting will come only if the attackers have to abandon the attack or are themselves shot down. BVRAAMs will be useful only if hostile defending aircraft on the approach to the target are detected and identified as hostile - which is something that may or may not happen. The best case scenario would be that the escorts draw away attention towards themselves while the attacking aircraft either overfly and bomb the target or launch standoff weapons and then exit. If the attacking aircraft and defending aircraft split apart to make it more difficult for the hostile interceptors - IFF will become an issue . One must not shoot off a BVR at one's own.

The attack mission into hostile territory itself may be to get the enemy to turn on his radars and he may turn on ground based radars, radars from interceptors or from an AWACS. The escorting fighters BVRAAMs come into the picture only in case of the latter two being detected. For ground radars the attacking aircraft will have to do some mud moving.

In the case of CAP over our own airspace - there will likely be some extra information from our own radars and perhaps and AWACS - so the chance of getting a hostile attacker with a BVRAAM increases.

No fly zones over hostile territory is something NATO have practised since Kosovo - honed by experience over Iraq, Afghanistan and Syria. That is probably the best scenario to take BVRAAM pot shots.

[Cain Marko]

One option for multi-carriage of weapons on a single pylon with good aerodynamics would be to use stealthy external pods.

I have always wondered about the rcs on that podded hornet vs say a typhoon or rafale carrying 4 aam recessed underbelly and 2 on wing tips. The latter will certainly win out on drag and kinematics I suppose. Something like this...



http://www.defenceaviation.com/wp-conte ... ghter1.jpg

[srai]

The issue with semi-recessed AAM on LCA would be redesign effort since that may be a pretty big change to the platform itself. Besides on a small LCA platform it may only be possible to semi-recess two BVR in the centerline area.

[shiv]

I am not at all sure that it can be assumed that semi-recessed is better than hanging off a pylon.

Extra weight is extra drag. It also means less fuel, less range and less manoeuvrability

Aerodynamic drag will have to be assessed in wind tunnel and live carriage tests

Pylons have the adapters needed to hold and launch a missile and these have to be accommodated in the fuselage - so any aircraft with semi recessed mijjiles will have that extra space in the fuselage unlike YellSeeYay

Launch conditions required for a missile launch may be quite different for semi recessed versus pylon mounted.

[DrRatnadip]

The real ones on the real aircraft. Clearly not soap bars for a real aircraft, but antennae. My guess was IFF.





Clearly smaller than the one on display at the AI-'17 show

As per reply i got from tejas fb page admin they are GPS antennae..

[JayS]

I am not at all sure that it can be assumed that semi-recessed is better than hanging off a pylon.

Extra weight is extra drag. It also means less fuel, less range and less manoeuvrability

Aerodynamic drag will have to be assessed in wind tunnel and live carriage tests

Pylons have the adapters needed to hold and launch a missile and these have to be accommodated in the fuselage - so any aircraft with semi recessed mijjiles will have that extra space in the fuselage unlike YellSeeYay

Launch conditions required for a missile launch may be quite different for semi recessed versus pylon mounted.

Its pretty valid assumption to consider semi-recessed missiles to have better aerodynamic configuration than the usual hanging by the pylon arrangement, in absence of any specific information stating otherwise. Induced drag due to extra weight would be a smaller component compared to the interference drag, and one which cannot do anything about. But semi-recessed config would definitely reduce interference drag.

But given LCA's size, recessed missiles is not an option.

Frankly, I don't see all the point of putting too many missiles under LCA. In pure A2A role 4CCM + 4BVR is more than sufficient, IMO. Anything more than that would be of little practical value, given increase in drag and reduction in agility and combat radius. But its the IAF which has to decide for this. All such modifications should be based on what IAF (or export customer) really wants/can use.

[JayS]

They are not prioritizing multi-rack BVR carriage as it is difficult to envision a scenario where a light fighter has not entered close combat even after firing two BVRs.

That is a serious mistake (IMHO) on their part given the issues with per missile reliability for most worldclass missiles and the need to launch multiple missiles per target for decent Pk.

Agree completely. I would like to see 4 BVR while having inboard pylons free for EFTs. The centre pylon cannot take the bigger EFTs IIRC. So having inboard pylons free would give ability to carry two big EFTs. This would give LCA very good Range/on-station time for CAP or even for escorting missions. Lets not forget its the peacetime where the jets spend most flying time i.e. CAP as far as A2A role is concerned, and the more we conserve airframe life in peacetime missions the better it is. So to have free inboard pylons while carrying 4BVR, it would need either 2x on each mid-board pylon or one each on mid-board pylon + 2 in tandem on centre pylon.

[JayS]

Do you know why the SPJ here has such blunt nose..??

Jay, its an ELTA EL/L-8222 with the radome in the front. See:
http://www.iai.co.il/sip_storage/files/7/27537.pdf

What I wanted to know is why can't it use streamlined nose..? From the CFD simulation, its easy to see high pressure right in front of the square-ish blunt nose.

Interestingly, the PDF you linked says this SPJ pod has "low drag"..!!

[JayS]

Do you know why the SPJ here has such blunt nose..??

Perhaps an off-the-shelf design that was being considered for the SPJ? Clearly, the paper indicates that the drag increase with that shape is far more than that with a CCM, so some aerodynamic housing for the SPJ will be required, without compromising on its performance.

Of coarse. But why such blunt nose..? Is it a limitation of the avionics inside that a blunt nose is a must..?

[JayS]

They are actively...? Your statement ended abruptly.

I cannot understand how they cannot envision such a scenario, especially when it lends so much more flexibility to the overall loadout. The 4 BVRAAMs would give the Mk1A the choice to avoid entering close combat, especially if they were to encounter a large enemy fighter package. Fire the BVRAAMs, and the AESA should be able to guide them while the Tejas Mk1A would be turning away. The AESA radar should be able to handle 4 targets simultaneously, right? Or is that a limitation they anticipate?

I'm assuming you're talking about the mid-board pylon being used for twin carriage of BVRAAMs? The twin racks would allow 4 Derby ER/Astra and 2 Python V to be carried with a centerline fuel tank, or inboard drop tanks, or a 1000 lb bomb or LGB. the paper indicated that the outboard hardpoint was being considered for twin CCMs, not BVRAAMs, perhaps due to the higher weight of BVRAAMs versus CCMs.

I would also like 4 BVR option. I don't think RADAR is an issue here. But the missile effectiveness itself is an issue. We are still not at a stage where single BVR missile can guarantee 100% pk. Karan has already pointed out this. If you launch at quite a long range, the missile is stretched too far and would not have much energy left to pursue a hard manoeuvring enemy. So 2 per bogie is what I think they will use.

But when we have our SFDR, things could change. At least for the 40-60km range.

[JayS]

Speaking about multi-rack, this one is pretty insane-4 of them.

The size of the aircraft matters.

[srai]

...
Frankly, I don't see all the point of putting too many missiles under LCA. ...

Makes a great poster though

[tsarkar]

We've ample experience with BVR or CCAAM dual racks, given that original Sea Harriers came with dual racks for Magic-1 that were upgraded to Magic-2 and finally upgraded to Derby.

A small data point - when the heavier Derby was added to LUSH, there was no rona-dhona on wing re-design.

The Harrier is a small plane limited by its unique engine, no extensive use of composites, yet it had sufficient design margins to accommodate a heavier missile without re-design / re-build.

[srai]

^^^

Well ... if you over-design then there is weight penalty. Design trade-offs

On the other note, who did all the Harrier dual-rack integration? Besides, how much pylon loading was that outermost designed for to begin with? Those are questions that need to be answered first. No two designs can be compared like apples-to-apples.

[shiv]

Induced drag due to extra weight would be a smaller component compared to the interference drag,

I am no aircraft designer or aerodynamics expert - only a man in need of dental care perhaps - but a 150 kg missile on a pylon means that the pylon should be stressed to at least 6G manoeuvres in flight - ie up to 900 kg. (actually more because of pylon weight)

The wing and fuselage hardpoints are already designed for that and more. Unless the under-fuselage airframe already has other points to attach a 150 kg weight (per semi-recessed missile) - again stressed to at least 6G if not more and the weight increase resulting from that strengthening, in addition to the associated weight of clamps/locks, cabling and release mechanism and perhaps a coolant gas bottle for IR and the space inside the fuselage for all that - my assumption is that the aerodynamic gain of semi recessed missiles may become negligible with these overheads. A sleek boxful of missiles like the pic posted by Singha maybe just as good.

Semi recessed missiles made sense on the Tornado because they were then free from the complexity of the variable geometry wing. Some semi recessed munitions in older aircraft were used because they could not be slung below because of their wingspan or body diameter compared to undercarriage length. Someone correct me if I am wrong but among AAMs only Sparrows and their bilayati cousins were carried semi recessed. The F-15 carries AMRAAMS on pretty little pylons. The Sparrow with a 36 in wingspan was bigger than R-27 or AMRAAM wingspan and that may be why they had to go through all that trouble to semi-recess it rather than aerodynamic considerations

If anyone has hands on experience of these things I would like to hear about it.

[tsarkar]

Well ... if you over-design then there is weight penalty. Design trade-offs

There is a fine art of designing with allowance for future growth margins and over-design. Growth margins is not synonymous to over-design, nor is growth margin directly proportional to weight penalty.

On the other note, who did all the Harrier dual-rack integration?

The Sea Harrier was originally equipped with dual racks for Sidewinder but uncle refused to sell us any. So we got racks equipped with Magic-1, that the French designed keeping interface points similar to Sidewinder. Then we got Magic II late 80s/early 90s.

The British retired the Harrier in 2006 around same time HAL was awarded LUSH. The Derby pylons were provided by Rafael and integrated by Naval Aircraft Yard Kochi and HAL. No BAe involvement.

Besides, how much pylon loading was that outermost designed for to begin with?

BAe didnt know when IN placed Sea Harrier order in 1979 that IAF will equip the aircraft with Derby in 2007. Infact the Derby didn't even exist then.

But growth margins were factored and hence, IN, HAL & Rafael didnt go to BAe for wing re-design.

Point being made is weapons too follow Moore's Law and become obsolete. There is no way of predicting in 1979 what weapon will come in 2007. Which is why growth margins are factored.

The R-60 to R-73E isn't user perfidy as was claimed in this forum. When arming Sea Harriers with heavier Derby and MiG-21 with heavier Magic-II, it was a complete non-issue.

This article mentions we even integrated Magic-II with MiG-23 https://www.forecastinternational.com/a ... _RECNO=592

Compared to 43 kg R-60, the Magic weighs 89 kg. The Magic-2 seeker was much more effective than AIM-9M Sidewinders sold to Pakistan along with F-16s

[shiv]

Sea Harrier from BR:
http://www.bharat-rakshak.com/NAVY/Avia ... rrier.html

Weapons: The aircraft has four wing and three under-fuselage stations. The inner wing pylons carry drop tanks of 900 kg each. The two outer wing pylons can carry up to 450 kg each.

The outboard pylons are more than adequate to carry the Derby in terms of weight

[vina]

Sea Harrier from BR:
The outboard pylons are more than adequate to carry the Derby in terms of weight

Ah, is outboard pylon of Harrier == Outboard Pylon of LCA ?

Harrier Wing Span - 7.6m ---- Tejas Wing Span - 8.2 m

Outboard Pylon of Harrier == MIDBOARD Pylon of LCA.
Outboard Pylon Harrier - 450Kg capability --- MIDBOARD Pylon of LCA - 1000 Kg (I think 1200Kg)
Outrigger Wheel of Harrier === Outboard Pylon of LCA - == 250KG (good for dual pylon IR missiles)

So if we want to see "adequate margins in design " , add a wingtip staton on the Harrier like we see in the Gripen, F16 and SU -30 , put in a 250 Kg missile there and then talk.
Other wise, I will put in a 10 Rack CCM on the Midboard of LCA or, 3 rack of 500 Kg in LCA mid board and claim victory and "strategic upper hand".
Have a nice day.
ps:
Does it matter where you hang stuff from ? Pliss to see .


(this one has answers on why it is so)

[JayS]

I am no aircraft designer or aerodynamics expert - only a man in need of dental care perhaps - but a 150 kg missile on a pylon means that the pylon should be stressed to at least 6G manoeuvres in flight - ie up to 900 kg. (actually more because of pylon weight)

The wing and fuselage hardpoints are already designed for that and more. Unless the under-fuselage airframe already has other points to attach a 150 kg weight (per semi-recessed missile) - again stressed to at least 6G if not more and the weight increase resulting from that strengthening, in addition to the associated weight of clamps/locks, cabling and release mechanism and perhaps a coolant gas bottle for IR and the space inside the fuselage for all that - my assumption is that the aerodynamic gain of semi recessed missiles may become negligible with these overheads. A sleek boxful of missiles like the pic posted by Singha maybe just as good.

Semi recessed missiles made sense on the Tornado because they were then free from the complexity of the variable geometry wing. Some semi recessed munitions in older aircraft were used because they could not be slung below because of their wingspan or body diameter compared to undercarriage length. Someone correct me if I am wrong but among AAMs only Sparrows and their bilayati cousins were carried semi recessed. The F-15 carries AMRAAMS on pretty little pylons. The Sparrow with a 36 in wingspan was bigger than R-27 or AMRAAM wingspan and that may be why they had to go through all that trouble to semi-recess it rather than aerodynamic considerations

If anyone has hands on experience of these things I would like to hear about it.

Minor correction - by interference drag I actually meant the increased drag counts of Cd_0 which is zero lift drag, drag when no lift is being produced (skin friction + pressure + interference + wave drag if any).

The overhead you pointed out are at best constant in both the cases - semi-recessed or pylon mounted. In fact in semi-recessed case you may not need the pylon at all, only the launcher would do, which is embedded inside the fuselage itself. Plus since its nearer to the airframe structure, less linkages so less material needed, less weight. Now on top of it, you have advantage in basic drag, (skin friction + pressure drag) since its exposing only a part of missile in semi-recessed case. While with pylon it is exposing the complete missile + launcher + pylon. On top of it there is interference drag between various stores or between missile and airframe. With semi-recessed arrangement you can almost eliminate this component. So you could have advantage on reduced overall weight and much less Cd_0. Of coarse this is theoretical possibility and how much actual gain would be, is dependant on the actual aircraft and amount of modification needed to make it happen.

Having said that, I don't think it can be done for LCA (too small aircraft). The weapons box holding a number of weapons could be a good compromise, but it needs to be checked in details how effective it is in reality given small size of LCA.

[JayS]

But growth margins were factored and hence, IN, HAL & Rafael didnt go to BAe for wing re-design.

Incorrect assertion to draw based on what info you posted, unless you have a specific info saying so. Else there can be perfectly valid engineering arguments made to show otherwise.

[tsarkar]

^^ By the same twisted Lahori logic & Madarssa mathematics, the Tejas outer hardpoint too should be stressed for 450 kg. Outer = Outer, right? Since when did middle of wing become outer?

The point was about design margins in MiG-21, MiG-23 and Sea Harrier hardpoints and not number of hardpoints.

Just like Islamic fundamentalists believe that civilization & religion didn;t exist before Muhammed and destroy all evidence to the contrary like Bamiyan Buddha statues, similarly some Tejas fundamentalists believe aircraft with better capability didn't exist before Tejas, and lie to prove their point

add a wingtip staton on the Harrier like we see in the Gripen, F16 and SU -30 , put in a 250 Kg missile there and then talk.

The Harrier GR 9 had four hard points per wing, including an outer hardpoint stressed to carry Paveway IV weighing 500 lbs 225 kg, that is almost double the weight of Derby.





Can the Tejas can carry a 500 lbs / 225 kg bomb on its outer wing hardpoint?

So the basic premise of outer hardpoint can carry light missiles like R-60 is incorrect, and it was the Tejas designer's fault of not keeping any growth margin in the outer wing hardpoint.

Adding new missiles to replace new ones was done for MiG-21, possibly MiG-23 and Sea Harrier without the rona-dhona of,"oh, my outer wing hardpoint was designed only for 43 kg R-60. Very bad user upgrading missiles and changing specs."

[tsarkar]

But growth margins were factored and hence, IN, HAL & Rafael didnt go to BAe for wing re-design.

Incorrect assertion to draw based on what info you posted, unless you have a specific info saying so. Else there can be perfectly valid engineering arguments made to show otherwise.

I stand by my PoV that IAF & IN added new missiles as older ones became obsolete, and their aircraft, whether MiG-21 or Sea Harrier, had hardpoints with adequate margins to allow them do so without major re-design as required for Tejas outer wing hard point.

I would be happy to learn incase you have any alternate / additional facts and logic to my above PoV.