China Military Watch

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Postby Rakesh » 09 Feb 2008 08:41


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Postby Rahul Shukla » 09 Feb 2008 10:11

Rahul Shukla wrote:Ok,

Here's a wiki page listing the names of all chinese airbases by military districts: clicky

And here is the bestest arrangement to study PLAAF airbases in all of China. Click here and the link opens up a Google page showing all PLAAF bases in all military districts. Then click on the link titled 'View In Google Earth' on the top RHS (just top & left of 'Maps') and you're all set...

We need to study the altitude of the airbase to determine the approximate air density, length of runways to determine which aircraft can use the airbase, distance of the airbase from the Indian border, and most importantly the weather patterns in the area (s) to determine the availability window of the airfields for offensive/defensive operations. Also need to find the railway tracks. Search around Lhasa and track them...
Last edited by Rahul Shukla on 11 Feb 2008 00:40, edited 1 time in total.

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Postby vivek_ahuja » 09 Feb 2008 12:23

Guys,

Based on some of the arguments of the previous avatar of this thread, I have posted some of the analysis that I had some time ago regarding PLAAF Air-Power in Tibet. As you can imagine, the analysis is extremely convoluted and complex to present full in words here, but I figured you guys can understand the posted information's relevance (if any).

I have started out with range and load envelopes for the A-5 here:

CHINESE AIRPOWER IN TIBET: PART-1
A-5/Q-5 FANTAN FLIGHT PERFORMANCE IN THE HIMALAYAS


PERFORMANCE FOR OPTIMUM BATTLEFIELD INTERDICTION IN ARUNACHAL PRADESH. (MAX LOAD-OUT IN WEAPONS AND MINIMUM RANGE REQUIREMENT LIMIT OF 250 Km)

Typical Launch location for given range: GONGGAR, LHASA
Role: BATTLEFIELD INTERDICTION IN ARUNACHAL PRADESH (MAX LOAD IN WEAPONS)
Runway Length: 12000 FEET (MAX)
Image

LOAD-OUT OPTIONS CHART:

a) MAX LOAD plots:
4 X 500Kg bombs
or 6 X 250Kg bombs
or 50Kg bombs depending on weapon carrying capacity (refer chart for values at different locations)
or 6 X Miscellaneous Rocket/Cluster bombs
and remainder payload capacity as internal fuel

b) MAX RANGE plots:
maximum internal fuel and two drop tanks of these sizes:
2x300 Gal
or 2x200 Gal
or 2x105 Gal
selection of either depending on payload capacity and range data and remainder payload as weapons

LOAD AND RANGE FOR GIVEN CASE OPTIMIZATION VERSUS AIRBASE ALTITUDE:
Image

LOAD AND RANGE FOR GIVEN CASE OPTIMIZATION VERSUS RUNWAY LENGTH:
Image
This graph has been optimized for the battlefield range specified earlier with only internal fuel and full weapons load on the pylons.



If you guys like me to post these analyzes, let me know accordingly. I figured that I can present this kind of analysis for various PLAAF aircraft types for discussion.

What do you guys think?

-Vivek
Last edited by vivek_ahuja on 12 Feb 2008 00:19, edited 5 times in total.

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Postby alokgupt » 09 Feb 2008 12:43

vivek_ahuja wrote:Guys,
I have started out with range and load envelopes for the A-5 here:

CHINESE AIRPOWER IN TIBET: PART-1
A-5/Q-5 FANTAN FLIGHT PERFORMANCE IN THE HIMALAYAS


CASE-1: PERFORMANCE FOR OPTIMUM BATTLEFIELD INTERDICTION IN ARUNACHAL PRADESH. (MAX LOAD-OUT IN WEAPONS AND MINIMUM RANGE REQUIREMENT LIMIT OF 250 Km)

If you guys like me to post these analyses, let me know accordingly. I figured that I can present this kind of analysis for various PLAAF aircraft types for discussion.

What do you guys think?

-Vivek


Finally an aero engineer to present the facts. We can use the graphs and once and for all put to rest the useful payload on each of these aircarft in Tibet: J-11/Su 27, J-10, J-8II, and J-7.

http://www.sinodefence.com/airforce/fighter/default.asp

Lhasa Gonggar air field is at 13100 feet altitude and has runway length of 4000 m. Based on your graphs I see that Q-5 can take off with load of 1000kg and have a range of 300km - 400 km.
Last edited by alokgupt on 09 Feb 2008 13:01, edited 2 times in total.

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Postby vivek_ahuja » 09 Feb 2008 12:47

ADDED LATER: Combined with previous graphs
Last edited by vivek_ahuja on 11 Feb 2008 03:18, edited 2 times in total.

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Postby JCage » 09 Feb 2008 13:25

Guys, for an effective operational aircraft, it has to have at least 10-15 mins of fuel for repeated passes over the target area, and a similar reserve for emergency relocation ie current airstrip is inoperative for recovery. Please note that pilot SAR is for all intents and purposes infeasible in the Himalayan region. Operating radius is hence reduced by a corresponding amount. It becomes even worse when we consider that mission planning is not linear, ie direct line to target.

You have to add another 50-100 km's worth of range to bypass AD threats and even factor in fuel reserve for combat (ie what do you do when you get bounced). In short, a ~300-400 km ranged fighter isnt going to hack it in the scenario we envisage. Point defence at best.

Vivek, nice graphs- are you generically modelling it, or basing it on some specific aircraft parameters? Edited:- I got your mail id from the other thread & we can discuss it further, and I'll also see if I can get my old Q-5 etc stuff across to you.
Last edited by JCage on 09 Feb 2008 13:37, edited 1 time in total.

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Postby vivek_ahuja » 09 Feb 2008 13:35

Guys, for an effective operational aircraft, it has to have at least 10-15 mins of fuel for repeated passes over the target area, and a similar reserve for emergency jettison. Please note that pilot SAR is for all intents and purposes infeasible in the Himalayan region. Operating radius is hence reduced by a corresponding amount.


True. My model at present is a relatively idealized model

Vivek, whats your basis for calculation- are you generically modeling it, or basing it on some specific aircraft parameters? Pass along your mail, and I'll see if I can get my old Q-5 stuff across to you.


Jcage, the model I created was for the optimization of the weapons load-out and range for variations in airbase altitude from where the aircraft takes off and the runway length. Next step I am taking is considering other parameters, but at this point the analysis takes into account basic airframe and engine performance data like different weights, engine intake and outlet data, pressure ratios, lift and drag coefficients, on ground take-off acceleration and so on and merely analyzes them for changes in thrust and lift and so on and calculates airframe performance against the attached atmospheric model.

Even so, the model is simply a bracketing exercise wherein I provide the limits of the performance with a fair degree of margin for error. As I get time I will update the model to include more parameters like specific variations in weapons load-outs and so on.

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Postby JCage » 09 Feb 2008 13:44

Its great work.

IMHO, the only true proper fighters that we can face and which meet these criteria of range without compromising significantly on payload are the Flankers. With a 1500 km radius, they can manage to deliver a moderate payload, and have enough initial thrust to manage a takeoff, and can settle into subsonic cruise thereafter to save fuel. To ensure maximal effective payload, against IAF facilities- imho, PGMs ie Russian KAB series will be used.

But given that only a few (% wise) of the fleet is configured for the PGM strike role, imho we are going to see a lot of the burden fall on the Su-30 MKs. The J-10 etc are unknown quantities, its hard to distinguish between the hyperbole and the hype about the types true capabilities, I guess we'll get to know in a few years time when more data is available.

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Postby vivek_ahuja » 09 Feb 2008 13:50

IMHO, the only true proper fighters that we can face and which meet these criteria of range without compromising significantly on payload are the Flankers. With a 1500 km radius, they can manage to deliver a moderate payload, and have enough initial thrust to manage a takeoff, and can settle into subsonic cruise thereafter to save fuel. To ensure maximal effective payload, against IAF facilities- imho, PGMs ie Russian KAB series will be used.


Yeah. It would be nice to get some similar graphs out of the current analysis model for the SU-30MKK series aircrafts,though it would take me some time to get it done. If I make some changes in the model to include factors like the time over target and so on, we can actually produce a set of graphs that can then be compared against a geographical overlay (from something like Google-earth or something) and plot out acttack radii for weapon configurations and airbase locations.

What do you think?

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Postby JCage » 09 Feb 2008 15:13

Great idea!

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Postby alokgupt » 10 Feb 2008 10:51

[quote="alokgupt]Lhasa Gonggar air field is at 13100 feet altitude and has runway length of 4000 m. Based on your graphs I see that Q-5 can take off with load of 1000kg and have a range of 300km - 400 km.[/quote]

Well I didn't read the graphs correctly last time.

PART-1/CASE-1: The graph just shows that max load cannot be supported even with minimum range of 250 km. Since max load cannot be supported there is not much sense in calculations based on that graph.

PART-1/CASE-2: At 13100 feet altitude and runway length of 12000 ft (max in your calculations) we can see that 1000kg weapon load can be supported in LO-LO-LO configuration to 400KM and HI-LO-HI configuration to 600KM.

So there are only two real impact of taking from Lhasa Gonggar air field:

1) Max payload cannot be supported for any kind of meaningful range.
2) Payload is cut 25% for the same range.

Did I miss anything?
Last edited by alokgupt on 10 Feb 2008 11:15, edited 1 time in total.

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Postby vivek_ahuja » 10 Feb 2008 11:08

Can you explain how are you plotting range of aircraft by altitude of the airfield? Are there any minimum payload requirements in your calculations? The reason I ask that is because I see that Q-5 payload is cut in half while its range is cut three times in your graph above. I would expect that it should be possible to reduce the payload (weapon load) to gain more range (fuel load)


Of course. The main model for running the for Case-I (Battlefield Interdiction) was that there was a minimum range that should be achieved at all times while the load was obviously limited to the maximum that the pylons can carry. For Case-I, this range value was a minimum of 250 Km and max load is 2000 Kg (structurally speaking).

Now having said that, the aircraft weight (inclusive of basic gun ammo weight) remains fixed. So the variations in altitude affect the total fuel+load weight term only. between this value, fuel and load are varied for various case studies. so for case-I it was as mentioned above while for Case-2 it was to have maximum range with the remainder weight left over from fuel being used to satisfy various weapons configurations.

So what you are asking with respect to range then fits under the case-2 study, where we are trying to maximize the range at the expense of payload. These two cases present the limits for maximum load or maximum range. In between the cases vary. I have that data with me but its very bulky to put here because of the various combinations that can be made. Hence I presented some simple cases here. (refer the load-out options chart for the two cases)

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Postby alokgupt » 10 Feb 2008 11:22

vivek_ahuja wrote:
Can you explain how are you plotting range of aircraft by altitude of the airfield? Are there any minimum payload requirements in your calculations? The reason I ask that is because I see that Q-5 payload is cut in half while its range is cut three times in your graph above. I would expect that it should be possible to reduce the payload (weapon load) to gain more range (fuel load)


Of course. The main model for running the for Case-I (Battlefield Interdiction) was that there was a minimum range that should be achieved at all times while the load was obviously limited to the maximum that the pylons can carry. For Case-I, this range value was a minimum of 250 Km and max load is 2000 Kg (structurally speaking).

Now having said that, the aircraft weight (inclusive of basic gun ammo weight) remains fixed. So the variations in altitude affect the total fuel+load weight term only. between this value, fuel and load are varied for various case studies. so for case-I it was as mentioned above while for Case-2 it was to have maximum range with the remainder weight left over from fuel being used to satisfy various weapons configurations.

So what you are asking with respect to range then fits under the case-2 study, where we are trying to maximize the range at the expense of payload. These two cases present the limits for maximum load or maximum range. In between the cases vary. I have that data with me but its very bulky to put here because of the various combinations that can be made. Hence I presented some simple cases here. (refer the load-out options chart for the two cases)


Got it. Can you validate my deduction for a third scenario?

Third scenario: No external drop tanks. Just internal fuel. How does the graph for payload vs range differ from when airfield is located as sea level?
Expected results: "Payload is cut 25% for the same range."

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Postby alokgupt » 10 Feb 2008 11:38

Comparision of known specs for J-10 and Tejas:

Tejas J-10
Empty 5500 8300
Length 13.2 15.5
Height 4.4 4.78
Span 8.2 9.7
Area 38.4 50
Dry 5600 8116
AB 8636 12525

T/EW 1.02 0.98
T/MW 0.45 0.45
Fuel/EW 0.45 0.54
Fuel/MW 0.20 0.25
Load/EW 0.73 0.78

Max Fuel 2468 4500
Max Load 4000 6500
Normal 8500 10500
Max Weight 12500 18000
Aspect 1.75 1.88
Dry / span 0.83 0.86

Scenario 1:
Fuel 1560 2232
Load 1000 1000
Weight 8060 11532
Wing (1) 210 231
T/W (1) 0.69 0.70
T AB /W (1) 1.07 1.09

Scenario 2:
Fuel 2500 3375
Load 2500 2500
Weight 10500 14175
Wing (2) 273 284
T/ W (2) 0.53 0.57
T AB/ W (2) 0.82 0.88

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Postby vivek_ahuja » 10 Feb 2008 11:39

Okay. Let me understand what you are saying for your third scenario: sea level comparison for same range, but payload variations, right?

In this case at sea level the A-5 on a LO-LO-LO profile is designed to move for 400Km on internal fuel with a payload of 2000Kg. whereas for Lhasa, at ~13000 feet, the graph is showing me it can only achieve the same range for 50% reduction in load. And even then it is carrying 2x150 Gal drop tanks, so the actual warload is around 500Kg or 2x250Kg bombs (one on each wing pylon)

It just cannot make the sea level range of 400 Km on internal fuel alone (hence two small drop tanks)

P.S.: I have updated the graph for Case-2 for range since it was showing a maximum load greater than that structurally possible. Sorry about that. Its now much clearer, I think.

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Postby alokgupt » 10 Feb 2008 11:43

vivek_ahuja wrote:Okay. Let me understand what you are saying for your third scenario: sea level comparison for same range, but payload variations, right?


Correct.

It just cannot make the sea level range of 400 Km on internal fuel alone (hence two small drop tanks)


This is the part I don't understand. The altitude of the airfield should only impact payload and not range (assuming that you are willing to sacrifice the payload for range) except when altitude is such that aircraft cannot take off even with just the weight of internal fuel (no payload). But given that the graphs show me that it is possible to take off with 1000 kg payload and additional 2 drop tanks, that is not the case. Any ideas on what I am missing?

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Postby vivek_ahuja » 10 Feb 2008 11:55

This is the part I don't understand. The altitude of the airfield should have no impact on range when you are willing to sacrifice the payload for range except when altitude is such that aircraft cannot take off even with just fuel (no payload). But given that you show me that it is possible to take off with 1000 kg payload and 2 drop tanks, I don't think that is the case. Any ideas on what I am missing?


True, but see the flight profile: LO-LO-LO. this at sea level is different that a similar flight in the Mountains because it is a relative term regarding the altitude above the local ground.

In the Himalayas, even the LO-LO-LO mission is actually at high altitudes, and hence my model calculates the reduction in range since the fuel consumption is much more to maintain a required thrust level. This is why the range decreases.

But as you say, range can be maintained at the cost of payload. So an A-5 flying from Lhasa will be able to fly 500Kg worth of bombs for 400Km range but only because it was also carrying two additional drop tanks with it instead of bombs.

so it maintains the range just like sea-level, but ends up carrying drop-tanks.

Also note that the airfield length plays a role here. it determines the exact acceleration for a given thrust and hence the weight of the aircraft. in other words, the aircraft could lift off with the proper payload, but becasue it was producing less thrust than normal when aloft, it also ate up more fuel for the same flight.

Hope that helps.

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Postby vivek_ahuja » 10 Feb 2008 11:58

And an additional things is that my Model takes into account the type of weapons the aircraft can carry. So while the model plays around with the fuel versus payload values, in the end it has determine what set of weapons it can carry. So the 500Kg value. The range of the A-5 can be increased further if you consider that all of the payload is used as drop-tank fuel, but in this case the only weapons available for a ground mission are internal guns.

Added later: Note that even in a clean configuration, the range is reduced for an A-5 than a similar flight at sea level mainly because of the density reduction. So while at sea-level it can make a flight of 400Km with 2000Kg weapons load, in the Himalayas (assuming a take off from ~13000 feet airbase) it can make the same range only if part of the load is reduced to 1000Kg and full internal fuel plus part of 1000Kg warload being a combination of two drop-tanks (~500Kg) and two bombs (~500Kg, 2x250Kg 'Iron' bombs).
Last edited by vivek_ahuja on 10 Feb 2008 12:22, edited 1 time in total.

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Postby negi » 10 Feb 2008 12:16

Vivek saar I dont know as to what equations/algo you are using but as I see you have factored in thrust and the other engine parameters can you confirm
as to what sort of degradation in thrust are we talking about in case of LCA and say J-10 operating from an airstrip at about 15-20 kfeet.

I mean does your formula account for the bypass ratio of the engines ? for I believe J-10 engine has a high BPR as compared to Tejas so the former would suffer a steeper degradation in thrust with increase in altitude.

Btw thanks for publishing those specs , these indeed make things more clear while discussing IAF vs PLAAF scenario.

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Postby alokgupt » 10 Feb 2008 12:22

vivek_ahuja wrote:True, but see the flight profile: LO-LO-LO. this at sea level is different that a similar flight in the Mountains because it is a relative term regarding the altitude above the local ground.

In the Himalayas, even the LO-LO-LO mission is actually at high altitudes, and hence my model calculates the reduction in range since the fuel consumption is much more to maintain a required thrust level. This is why the range decreases.

Also note that the airfield length plays a role here. it determines the exact acceleration for a given thrust and hence the weight of the aircraft. in other words, the aircraft could lift off with the proper payload, but becasue it was producing less thrust than normal when aloft, it also ate up more fuel for the same flight.

Hope that helps.


Thanks. But I am still confused...if high altitudes cut down the range of the mission why will HI-LO-HI have more range than LO-LO-LO? Shouldn't it be other way around?

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Postby alokgupt » 10 Feb 2008 12:25

negi wrote:as to what sort of degradation in thrust are we talking about in case of LCA and say J-10 operating from an airstrip at about 15-20 kfeet.


The calculations published by vivek are for Q-5. It is not related to LCA vs J-10.

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Postby Lalmohan » 10 Feb 2008 12:27

chinese a/c could also take off from lower level airfields with higher payload and refuel in flight before crossing the mountains, but this will be limited to far fewer numbers

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Postby vivek_ahuja » 10 Feb 2008 12:34

Thanks. But I am still confused...if high altitudes cut down the range of the mission why will HI-LO-HI have more range than LO-LO-LO? Shouldn't it be other way around?


Sorry about not explaining that better. What you have to consider here is also the drag issue. the higher you go, the lesser the drag, but also lesser thrust. these are all looping equations without a closed solution.

Hence, while the HI-LO-HI range is slightly higher than the LO-LO-LO range in the himalayas, both are still less than their sea-level counterparts. it comes down to what issue is dominating the most in a given situation. That is, is your engine producing less thrust to affect the range more than the increment produced by reduced drag is? and vice versa.

also note that while thrust and drag are connected, the parameters that define them are not so clearly explained. so while the thrust is reduced (and hence the increase in fuel consumption) by a degree, the drag is reduced by another degree for altitude variation.

This was the reason I had to use a numerical iterative technique to get the solution, its just not distinct enough to do a performance analysis using a set of explicit formulae.

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Postby alokgupt » 10 Feb 2008 12:47

vivek_ahuja wrote:Hence, while the HI-LO-HI range is slightly higher than the LO-LO-LO range in the himalayas, both are still less than their sea-level counterparts. it comes down to what issue is dominating the most in a given situation. That is, is your engine producing less thrust to affect the range more than the increment produced by reduced drag is? and vice versa.


Thanks again. Another question:

But thinking of it another way air field altitude should only play a part in reducing pay load during take off. After take off range will depend purely on mission profile which is effected by terrain. It should impact IAF or CAF similarly. So will even IAF aircraft will have limited range because they have to operate at high altitudes in Tibet?

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Postby vivek_ahuja » 10 Feb 2008 13:02

Okay, this is a different topic altogether.

My analysis for the PLAAF aircrafts was mainly concentrated on the issue of their taking off from the ground being affected by altitude and runway length. this is because it takes a longer run on the runway to carry the same load in a PLAAF aircraft than it does an IAF aircraft in the plains outside the Himalayan region. But once they are up there, it is question of aircraft performance more than anything else.

In other words, depending on what altitude an aircraft is designed to fly with a certain load, the effects will vary. but the only difference for the PLAAF is that they will never be able to reach those design limits because of the take-off issue more than anything else.

So if an aircraft is designed for a 15000 feet ceiling (as an example), and you force it to fly at 20000 feet, it is going to affect its performance. but this is different from the take off situation.

so my reasoning is that the IAF aircrafts, although affected by the altitude issue like the PLAAF (depending on various aircraft types), will be able to deliver much larger loads for a given range simply because they were able to take off with those loads in the first place, while the PLAAF birds were not.

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Postby alokgupt » 10 Feb 2008 13:14

vivek_ahuja wrote:so my reasoning is that the IAF aircrafts, although affected by the altitude issue like the PLAAF (depending on various aircraft types), will be able to deliver much larger loads for a given range simply because they were able to take off with those loads in the first place, while the PLAAF birds were not.


This is entirely correct and I agree with that. My question was if there is a way to determine just the take off penality for PLAAF operating from Tibet vs IAF aircraft taking off from plains assuming the mission profile to be the same. :wink:

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Postby vivek_ahuja » 10 Feb 2008 13:31

My question was if there is a way to determine just the take off penality for PLAAF operating from Tibet vs IAF aircraft taking off from plains assuming the mission profile to be the same


The IAF is unlikely to have take-off penalty from the plains at all, assuming the major airbases have sufficient runway lengths to allow them to take their full design load in weapons for a given range.

only thing that will affect the IAF is the range issue at the given loads at high altitude. But the PLAAF will have both payload and range problems. So what can actually be compared is something along the lines of Fleet analysis wherein data is presented showing stuff like 10 Jags capable of carrying warload over a given range equal to that carried by 15 or 20 Q-5s or whatever, and even this will be very vague since the weapons types are different.

Actually, this was why I had first concentrated in generating individual aircraft performance charts before moving on to do air-power analysis charts. But it is certainly on the cards for a later stage on this thread. :twisted:

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Postby JCage » 10 Feb 2008 16:09

Vivek, mailed you some stuff you were querying about.

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Postby Aditya G » 11 Feb 2008 00:18

vivek,

if we can have an atlas the even with the theoretical aicraft ranges that will be much appreciated.

we can actually produce a set of graphs that can then be compared against a geographical overlay (from something like Google-earth or something) and plot out acttack radii for weapon configurations and airbase locations.

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Postby vivek_ahuja » 11 Feb 2008 03:04

Guys,

Ran the model for the J-8II today after making changes to include time over target and the corresponding range issues. Also updated the Q-5/A-5 charts to include the same.

Aditya, I will get to the map issue as soon as I have the data for all relevant aircraft. Currently I am doing these analysis for each aircraft type as I get time each day, so it might take some days for me to finish the analysis for all airbases in Tibet.

JCage, thanks for the info. Can you forward me that Q-5 data so I can see if my model for this aircraft can be improved?
Last edited by vivek_ahuja on 11 Feb 2008 03:19, edited 1 time in total.

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Postby vivek_ahuja » 11 Feb 2008 03:10

CHINESE AIRPOWER IN TIBET: PART-2 (J-8II PERFORMANCE ANALYSIS)

PERFORMANCE FOR LONG RANGED PENETRATION STRIKES WITHIN INDIA (MINIMUM LOAD-OUT IN WEAPONS AND MAXIMUM RANGE REQUIREMENT LIMITS)

Typical launch airbase: Dangxiong, Tibet
Role: LONG RANGE GROUND STRIKES (MAX LOAD IN WEAPONS)
Runway Length: 12000 FEET (GRAPH-2)
Image

LOAD-OUT CHART OPTIONS FOR GIVEN OPTIMIZATION:

a) MAX LOAD plots:
maximum weapons load of 4500 Kg limit and maximum possible internal fuel for given parameters.

b) MAX RANGE plots: maximum internal fuel of 4600 Kg (inclusive of 2x800L drop tanks on wing inner side pylons and 1x1400L centerline tank) and remainder load in weapons up to a maximum of 2250Kg on remaining pylons (airframe weight inclusive of gun ammo for all analyzes and not to be added here)

LOAD AND RANGE FOR GIVEN CASE OPTIMIZATION VERSUS AIRBASE RUNWAY LENGTH:

Image

LOAD AND RANGE FOR CASE OPTIMIZATION VERSUS AIRBASE ALTITUDE

Image
Last edited by vivek_ahuja on 29 Feb 2008 07:35, edited 3 times in total.

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Postby vivek_ahuja » 11 Feb 2008 03:37

Just an interesting conclusion for the J-8II: it turns out that the airbase penalty for this aircraft is at a minimum for variation in airbase altitude and only shows significant variation in airbase runway length. Something tells me that this aircraft was designed with operations in Tibet very much in mind.

still, where the aircraft has a problem is the full utilization of its large war load carrying capacity. Its advertised range of 800Km is achieved only through the use of the three drop-tanks (2x800L inner wing and 1x1400 Centerline) and that leaves only four hard points for carrying the weapons load. Further, since the fuel in the tanks is configured in the payload calculations, the actual load drops to half (from 4500 Kg around ~2200 Kg) in actual useful load.

and even here the payload cannot be carried to full capacity because of the runway length penalty as in Graph-I.

So my interpretation of this result was that if a J-8II takes off from Tibet without any in-flight refueling support, it will make the range given by the manufacturers only on a very light war-load unless it takes off from a suitable long runway. You can see the exact values in the first chart for MAX-LOAD versus MAX-RANGE criterion and compare the range and weapons load accordingly.

This should help in giving this aircraft's attack ranges and effectiveness for different airbase runway lengths and their distances from the border.

-Vivek

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Postby alokgupt » 11 Feb 2008 03:58

vivek_ahuja wrote:Just an interesting conclusion for the J-8II: it turns out that the airbase penalty for this aircraft is at a minimum for variation in airbase altitude and only shows significant variation in airbase runway length. Something tells me that this aircraft was designed with operations in Tibet very much in mind.

So my interpretation of this result was that if a J-8II takes off from Tibet without any in-flight refueling support, it will make the range given by the manufacturers only on a very light war-load unless it takes off from a suitable long runway. You can see the exact values in the first chart for MAX-LOAD versus MAX-RANGE criterion and compare the range and weapons load accordingly.


Great analysis as always. J-8II is more likely to be deployed in fighter / interceptor role and not in CAS/ Attack role. It only needs to take off with air to air missiles which seems like your analysis shows it can very well do even from high altitude air fields in Tibet. Sinodefence calls it "Interceptor fighter aircraft with secondary capability for ground attack".

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Postby vivek_ahuja » 11 Feb 2008 04:19

J-8II is more likely to be deployed in fighter / interceptor role and not in CAS/ Attack role. It only needs to take off with air to air missiles which seems like your analysis shows it can very well do even from high altitude air fields in Tibet.


Yeah, but still the range and endurance of the J-8II are problematic. With no in-flight refueling support, taking off from airbases in Tibet which are further north will mean that the patrolling time for CAP just behind the border and OCA missions is highly limited.

But you have to see it as part of a system. For example, even with the limited analysis done so far (only for the Q-5 and the J-8II), it is quite clear now that the Q-5 can only take off from forward airbases in Tibet (Around Lhasa) to be able to reach even the border with Arunachal Pradesh if they were to carry any useful load.

This means that supporting J-8IIs (as escorts perhaps) will have to be based from airbases such as Dangxiong to the north and this will mean that they will be unable to fly escort all through the forward and return legs of the Q-5 flights. And that creates a problem.

To make matters worse, Q-5s have shown in the previous analysis (refer the updated charts for the Q-5 where Time over target has been a factor added to affect range) to possess a ridiculously low carrying capacity for air-to-ground for the required flight distance to the Indian border. So, although I haven't done fleet and airbase capacity analysis yet, it might just turn out that other aircraft types might have to be thrust in by the PLAAF to compensate for the reduced effectiveness of the Q-5, and this might turn out to be aircrafts like the J-8II

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Postby alokgupt » 11 Feb 2008 04:36

vivek_ahuja wrote:
J-8II is more likely to be deployed in fighter / interceptor role and not in CAS/ Attack role. It only needs to take off with air to air missiles which seems like your analysis shows it can very well do even from high altitude air fields in Tibet.


But you have to see it as part of a system. For example, even with the limited analysis done so far (only for the Q-5 and the J-8II), it is quite clear now that the Q-5 can only take off from forward airbases in Tibet (Around Lhasa) to be able to reach even the border with Arunachal Pradesh if they were to carry any useful load.


Vivek,

There are four PRC air fields within 300 km to the Arunachal / Sikkim border. There only one within 50 km of the border. Based on your analysis we can say that Q-5 can only be staged from Nyingchi Kang Ko without refuelers. With refuelers hovering over the air field it can be deployed at max from additional three air fields. No one expects Q-5 to be deep penetration/ strike aircraft. There might be some use for them in CAS though.

As for J-8II it can be staged from any of these four airfields (within 300 km of AP / Sikkim border) and used as interceptors and minimally for CAS.

I will wait for your fantastic analysis on J-7 (as interceptors) in Tibet.

But it is clear that PRC will have to use Flankers or J-10 in strike or air dominance role.

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Postby Lalmohan » 11 Feb 2008 13:58

seems to me that given the operational limitations, the PLAAF will primarily focus on air defense over tibet since the IAF enjoys a clear advantage in the air. PLA would have advantage of attacking in numbers from a secure and easier supply chain (which IAF will be trying to disrupt) compared to IA. However, IAF has to go all out to interdict the supply chain if IA has any real chance of stemming a full scale invasion

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Postby Sanku » 11 Feb 2008 14:03

Lalmohan wrote:nd easier supply chain (which IAF will be trying to disrupt) compared to IA. However, IAF has to go all out to interdict the supply chain if IA has any real chance of stemming a full scale invasion


True; me thinks that cruise missile are ideal for this role though. Specially given the terrain the Chinese will be hard put to defend all the parts of their supply chain and plugging all in ingress routes.

Lots of cheap dispensable CMs with smart mutions/multiple fragmented warheads over main approach points will do wonder for their front line forces.

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Postby vivek_ahuja » 11 Feb 2008 14:55

There are four PRC air fields within 300 km to the Arunachal / Sikkim border. There only one within 50 km of the border. Based on your analysis we can say that Q-5 can only be staged from Nyingchi Kang Ko without refuelers. With refuelers hovering over the air field it can be deployed at max from additional three air fields. No one expects Q-5 to be deep penetration/ strike aircraft. There might be some use for them in CAS though.


That's the issue for the Q-5 because even for all these four airbases there are some common characteristics:
a) All four airbases are as you say, within 300 Km range of the border. That makes them all vulnerable to Indian cruise missile attacks during the initial hours of any campaign. This puts the PLAAF Q-5 fleet highly susceptible to being grounded at the airbases if one or two Brahmos slam into the single track runways

b) All four airbases have very small tarmac areas. These are airbases designed to hold the delivery node of aerial transport chains, i.e. the rotation of transport aircrafts supplying the regional regularly. I have not seen any dispersal areas, hardened shelters and the corresponding concrete track loops, redundant taxi-tracks etc at any of these locations that would allow a decent fleet of Q-5s to be based there. I am not saying it can't be done, but if it is done, then the above case (a) makes these locations juicy and soft targets.

c) These are the only accessable airfields for the Q-5 in Tibet. The only other airfield is Zhongdiang, and even that is out of range for the Q-5 because of the airbase altitude.

Further, the Chinese still maintain the Q-5 as their primary ground-attack aircraft with hundreds in service. Unfortunately, they just don't have the infrastruture in Tibet to use even 25% of that fleet effectively without risk of them being grounded at these locations or being stuck outside the combat regions.

To compensate for this, I am afraid they are going to have to send in other more modern aircraft types to fill in the gap left by the Q-5 in the CAS role, and hence the use of longer ranging J-8IIs in that role with perhaps part of the SU-27 fleet as well.

The range factor combined with altitude differences show that the Yunnan province is in fact ideally suited for launching aircrafts with maximum range options and decent weapons load. theoretically speaking, there is good reason from a technical POV for the Chinese to be thinking about overflying Myanmar airspace for attacking Indian targets. In fact, I wouldn't discard this possibility lightly.

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Postby alokgupt » 11 Feb 2008 17:53

vivek_ahuja wrote:The range factor combined with altitude differences show that the Yunnan province is in fact ideally suited for launching aircrafts with maximum range options and decent weapons load. theoretically speaking, there is good reason from a technical POV for the Chinese to be thinking about overflying Myanmar airspace for attacking Indian targets. In fact, I wouldn't discard this possibility lightly.


Agreed. A very real possibility given that this will allow PRC to use so many of the Yunnan province air fields. Although we need to keep in mind that PRC can upgrade the air fields relatively quickly when required.

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Postby alokgupt » 11 Feb 2008 18:06

Lalmohan wrote:seems to me that given the operational limitations, the PLAAF will primarily focus on air defense over tibet since the IAF enjoys a clear advantage in the air. PLA would have advantage of attacking in numbers from a secure and easier supply chain (which IAF will be trying to disrupt) compared to IA. However, IAF has to go all out to interdict the supply chain if IA has any real chance of stemming a full scale invasion


Very correct. But air fields can be upgraded relatively quickly when winning a war depends on it. Therefore I don't think it is right to base our long term military planning on just the air fields.


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