C-17s for the IAF?

[Gilles]

When Nyoma was recently adapted for fixed-wing operation, engineers whet there to compact the soil suitable for An-32 operation.

For any sustained operations, even An-32 can't be used in unprepared strips w/o any manitenance. Simlalry, if need arises to land heavy-lift aircraft for sustained operations, the ground will be prepared to handle that.

Except that a normal gravel runway will need maintenance every year after hundreds or thousands of aircraft have landed. But land a few C-17s and the runway will be unusable.

[Gilles]

There are no known instances of C-17 sustaining operations from dirt airstrips without damaging them and requiring extensive engineering support (for the runway).

Except of course when the dirt airstrip has been made to C-17 Standard using that manual I just referenced. Then, it can sustain just about any aircraft, once the runway is long enough.

Think of those runways as "SUPER" dirt runways, which the ALGs are not

[GeorgeWelch]

This table gives the minimum runway lengths for C-17s a various altitudes and at various RCR (runway friction index) The table only goes to 6000 Mean Sea Level. Its likely that above that altitude, the runway requirement greatly increases

So a C-17 cannot even land on a runway of 3500 feet at that altitude,let alone carry any payload

No, that refers to "a landing gross weight of 447,000 pounds", ie with 164,500 pounds of fuel+cargo. (That's an Arjun + 47,500 lbs of fuel for instance, enough to make a short hop back to a refueling base, or get airborne and rendezvous with your new KC-30 tankers )

Any decrease in landing weight will of course decrease landing distances.

Also it depends on the RCR of the runway.

If the RCR is 20, altitude has no effect whatsoever on landing lengths.

As far as altitude affecting landing distance, its impact seems rather small compared to the impact of RCR. Even on the softest soil, it only adds 1000' of distance for 6000' of altitude.

(Assuming we're talking about 3500' + 600' of overruns, or a 4100' runway as Gilles likes to call it.)

[Gilles]

If the RCR is 20, altitude has no effect whatsoever on landing lengths.

As far as altitude affecting landing distance, its impact seems rather small compared to the impact of RCR. Even on the softest soil, it only adds 1000' of distance for 6000' of altitude.

(Assuming we're talking about 3500' + 600' of overruns, or a 4100' runway as Gilles likes to call it.)

George Welch you are WAY in left field on this one.

Aircraft land using Indicated Airspeed (IAS) or in the case of large modern transports, Calibrated Airspeed (CAS). It is an airspeed indicated by the instrument but which has to be adjusted with pressure altitude and temperature to come up with the real airspeed of the aircraft through the air, called the True Airspeed (TAS). When the wind is calm, the True Airspeed is = to the Ground Speed (GS) which is the actual speed over the ground. So much for theory.

Lets assume the C-17 at a given weight, needs to land at 130 knots CAS. At Sea level, Standard atmosphere, meaning a Pressure of 1013.2 Mb and at an outside Air temperature of 15 degrees Celcius, CAS is equal to TAS. We'll also assume zero wind. So the aircraft will touch the ground at 130 knots TAS.

If we now need to land at the same weight, at standard atmosphere at an airport located at 6000 feet MSL, the temperature will be 3 degrees. The aircraft still needs to land at a CAS of 130 knots but the TAS, when computed will now be 142 knots. 12 knots faster than at Sea level.

At 10,000 feet, the temperature will be -8 but the same 130 knots CAS landing will represent 152 knots TAS. 22 knots faster than at MSL.

At 13,000 feet MSL, the temperature will be -11 and the 130 knot CAS will turn out to be 158 knots TAS, 28 knots faster than at MSL.

You really think that an aircraft which hits the ground at 130 knots uses the same runway as one that does so at 158 knots?

Do you think that its a coincidence that the longest paved runway in the world happens to be located at the airport that is the highest in the world ?


http://en.wikipedia.org/wiki/Qamdo_Bangda_Airport

[Airavat]

Military Aerospace

U.S. Air Force leaders on Tuesday ordered eight Boeing C-17 Globemaster III rapid strategic airlift aircraft designed to operate from main operating bases or forward operating bases with short or unimproved runways. Boeing will build the large cargo aircraft at its Global Mobility Systems segment in Long Beach, Calif., under terms of a $1.5 billion contract.

The C-17 is designed to operate from paved and unpaved runways as short as 3,500 feet and as narrow as 90 feet. Its thrust reversers can back the aircraft and reverse direction on narrow taxiways. The aircraft is large and powerful enough to carry the 70-ton M1 Abrams main battle tank. In addition to the United States, its operators include the military forces of Australia, Canada, India, NATO, Qatar, United Arab Emirates, and the United Kingdom.

[Surya]

Out of curiosity is there any aircraft in the heavy lift category which can sustain operations in unpaved runways without maintenance.

I would doubt it because I have heard of normal runways developing cracks under sustained heavy operations.

[arnab]

The right statement is IAF wants a modern heavy lift aircraft in response the recent directives from the PM to build capability to influence the region.

This is ALL that CAS has said and this ALL that I agree on.

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

Now the accusation stands...

Why no RFI?

Ah -'recent directives' by current PM? I think Indian strategy has evolved while you were sleeping

B Raman's article on the subject:

http://www.c3sindia.org/india/220

To Narasimha Rao, who was the Prime Minister between 1991 and 1996, should go the credit for enlarging the geographic orientation of India’s external policy. He took India’s policy-makers out of the morass of South Asia where they had got stuck for some years and beckoned them to look to South-East and Central Asia as new playing fields for India of the future. He similarly took India out of the morass of its Arab-centric Look West policy and beckoned India’s policy-makers to look to Iran as a compatible power of the future.

I think Narsimha Rao is responsible for India acquring C 17s

Added later: When you say - Why no RFI - I presume you think that no RFI had been sent to other aircraft manufacturers which make the 'C-17 class' of aircrafts (ACM's words). Perhaps you can tell us which aircrafts are there currently in the C-17 class? (Though earlier you were saying that IAF should have also sent an RFI to HAL) - presumably for receiving a 'Not Applicable' response ?

P.S. - Why paraphrase dishonestly with words like 'IAF wants Modern Heavy Lift aircraft' when the ACM's direct quote refers to 'hi-tech C-17 class' of aircrafts ?

[svinayak]

I think Narsimha Rao is responsible for India acquring C 17s

We have to give the credit to PM Rajiv Gandhi

[rohitvats]

<SNIP>

This may not meet your high standards of exactitude. But hey everyone here is speculating, right?

<SNIP>

If this the logic with which you intend to defend your assertions - then there is not much left to say.

There was a reason I commented on this thread that first casualty has been facts and any desire to learn on the topic. You very clearly bring out the example of the same - you could have very easily checked on the questions that I raised before even making that post of yours ( and me asking those questions of you) - Gilles has posted enough material on the C-17 short-runway performance (or lack there-off) and got the answers for yourself and for benefit of the others - but you chose to speculate and made basic & fundamental errors in your assertions.

I'm not for or against the purchase - but let us at least accept the facts and be more informed.

[Sanku]

I'm not for or against the purchase - but let us at least accept the facts and be more informed.

The facts are unpalatable, the facts will say what people are desperately trying to push into ground.

[Tanaji]

The facts are unpalatable, the facts will say what people are desperately trying to push into ground.

The facts are:

• Il76 does not carry the load required by the IAF. Il76 60 tons and Il476 are mythical paper planes
• An 124 100 is not available now and there is no known date on when it will be if at all
• A400 is delayed and is hopelessly backlogged.

Also, IAF prefers planes that are available *now* and meets its requirements. Hence there is no alternative to the C17 currently.

Anything else is fluff and kite flying.

[Tanaji]

Added later: When you say - Why no RFI - I presume you think that no RFI had been sent to other aircraft manufacturers which make the 'C-17 class' of aircrafts (ACM's words). Perhaps you can tell us which aircrafts are there currently in the C-17 class? (Though earlier you were saying that IAF should have also sent an RFI to HAL) - presumably for receiving a 'Not Applicable' response ?

Exactly, this whole RFI thing is a red herring. If one wants a F1 Formula car, would one send a RFI to Premier Padmini?

[rohitvats]

[*]Il76 does not carry the load required by the IAF. <SNIP>

<SNIP>

And on what basis did you arrive at this conclusion?

[Sanku]

[*]Il76 does not carry the load required by the IAF. <SNIP>

<SNIP>

And on what basis did you arrive at this conclusion?

This is a post facto analysis, the logic goes something like "since IAF did not send RFI that means there were no contenders, since if there were IAF would have, since IAF knows more than you"

The view that IAF is not god and hence is not really in a position to now what can be offered to it before it sends invites for detailed information is some how lost.

[Kanson]

When Nyoma was recently adapted for fixed-wing operation, engineers whet there to compact the soil suitable for An-32 operation.

For any sustained operations, even An-32 can't be used in unprepared strips w/o any manitenance. Simlalry, if need arises to land heavy-lift aircraft for sustained operations, the ground will be prepared to handle that.

Except that a normal gravel runway will need maintenance every year after hundreds or thousands of aircraft have landed. But land a few C-17s and the runway will be unusable.

You could be right, Sir. My statement is very much made in the Indian context. Nyoma ALG which was earlier supporting only heli operation was modified to support An-32. If for operating an An-32 type aircraft in ALG needs preparation of the runway, i'm sure, if IAF is willing to operate C-17 from there, ALG needs preparation and will be prepared suitably.

IOW, even this small An-32 was not operated in sustained mode without preparation from these ALGs.

[GeorgeWelch]

George Welch you are WAY in left field on this one.

I am quoting directly from the document you provided.

pg 13

RCR 20 - Pressure Altitude (feet) 0-6000 - Runway length (feet) 3500

In other words the required runway length does not depend on altitude for a RCR of 20.

[Surya]

So let me ask again

Out of curiosity is there any aircraft in the heavy lift category which can sustain operations in unpaved runways without maintenance on the runways.

[GeorgeWelch]

This is a post facto analysis, the logic goes something like "since IAF did not send RFI that means there were no contenders, since if there were IAF would have, since IAF knows more than you"

Or maybe it was something more like 'It doesn't carry all army vehicles.'

The view that IAF is not god and hence is not really in a position to now what can be offered to it before it sends invites for detailed information is some how lost.

Basic specs for all contenders are freely available. No god-like knowledge required, just a basic capacity to use the internet.

[Kanson]

So let me ask again

Out of curiosity is there any aircraft in the heavy lift category which can sustain operations in unpaved runways without maintenance on the runways.

Simple answer No. If it is Airship then it can.

[GeorgeWelch]

How does one decide that a particular manufacturing line or operation has been shut down and is in no position to be revived?

This particular question was in regards to the Il-76 not being able to meet the requirements.

Of course they don't need the internet to determine that, seeing as they are in possession of a few and know their limitations intimately.

[Tanaji]

And on what basis did you arrive at this conclusion?

I was referring solely to the IAF requirement for a very heavy lifter and not otherwise.

The IAF does perfectly fine right now with its Il76, and probably meets almost of its requirements with it. However, it evidently thinks that it requires a very heavy lifter that has a greater carrying capacity than the IL76. For what reason, I dont know, IAF has not deigned to tell us.. and thats the whole point. Saying IAF is wrong and it should stick with Il76 is second guessing it. One can second guess someone if one knew the reason and hence propose alternatives, but not otherwise.

[Anthony Hines]

Was there an RFI sent out before India decided to buy any of the following:
1. MiG 21
2. MiG 23
3. MiG 25
4. MiG 27
5. MiG 29
6. An 12
7. IL 76
8. T 72
9. T 90
10. Foxtrot subs
11. Kilo Subs
12. Kashin Class destroyers
13. IL 38 MD
14. Tu 142
15. BMPs
16. Etc etc etc

There seems to a pattern here in that the Indian government of the day decides what it wants. RFI be damned.

[negi]

^ Those were bought in an era when WEST was fighting imaginary ghosts of communism and India happened to be on the other side .
More importantly during the Soviet era we got most of those platforms at favorable terms and in most cases there was no western equivalent on sale. For instance even today Unkil wont sell anything in the league of a Tu-142M to India.

We bought the Mirages,Gnats and Vampires when we could .

[Gilles]

So let me ask again

Out of curiosity is there any aircraft in the heavy lift category which can sustain operations in unpaved runways without maintenance on the runways.

Simple answer No. If it is Airship then it can.

The IL-76 can. Its made to operate on unpaved runways, the regular kind of unpaved runways that are found throughout Asia, Europe, Africa, Australia, North and South America. An IL-76 that lands on unpaved runways makes no more damage to a runway than an An-32.

Just to demonstrate:

The An-32 has a maximum landing weight (MLW) of 26400 Kg on 8 wheels (3,300 Kg per wheel)
The IL-76 has a MLW of 135500 Kg (unpaved runways) on 20 wheels for 6,775 Kg per wheel.
The C-130J has a MLW 59,000 Kg (assault, unpaved) on 6 wheels for 9,833 Kg per wheel.
The C-17 has a MLW of 202,720 Kg (assault, unpaved) for 14 wheels at 14,480 Kg per wheel.

Even the most mundane passenger jet, the Boeing 727-200, which is unpaved runway approved (with certain modifications) has a MLW of 73,100 Kg on 6 wheels, for 12,184 KG per wheel and in fact has about the same Aircraft Classification Number as the C-17. Who would call the B-727 a STOL aircraft with unpaved runway capacity ?

This is not rocket science. Of course, landing gear geometry, size and pressure of the tires all play a role, but this example alone paints a clear enough picture of which aircraft are primarily meant for unpaved runways and which are not.

Read here

While the C-17 and the C-17ER can land on an airfield that is about the same size as that required for the C-130, they cannot land at their maximum unpaved landing weight on an unpaved runway structurally designed for the C-130’s maximum landing weight. Prior
to landing a maximum-weight C-17 or C-17ER on such a runway, an Air Force Special Tactics Team would need to analyze the condition of the landing surface and approve or disapprove its use. Since the C-17 and C-17ER maximum landing weight for semiprepared runways is almost three times the C-130’s maximum landing weight of 155,000 pounds, a C-17 airfield’s structural requirements are much greater than those of C-130-only airfields. The heavier the aircraft, the greater the load placed on the airfield structure during takeoff, landing, and taxiing. With an unpaved surface, the heavier load on the tires will tend to form ruts on runway surfaces. The heavier the aircraft, the deeper the ruts. The greater the number of aircraft passes, the greater the number of ruts.

[Gilles]

I just found a couple interesting documents.

This one which is a recent brochure prepared by Boeing to present the C-17 to Singapore.

It contains charts for take-off and landing distances.

I also found some guidance on how the military compute their take-off and landing distances here

For the take-off, they use a balanced field length, a bit like the civilians. For landing, they use an approach speed of 1.2 of the Stall Speed instead of 1.3 for the civilians and they DO NOT FACTOR in any margin for error. They just use the landing distance over a 50 foot obstacle with a braking coefficient of .30 (very good)

So for example, at 202 tonnes (Maximum Landing Weight, unpaved runway), at Sea Level, it will require about 3200 feet of landing distance if the runway is dry. That leaves 300 feet of margin for any error in the case of a 3500 foot runway (plus the two 300 foot stopways). If it was a civilian aircraft, it would require 5344 feet for a dry runway and 6145 for a wet one.

At 6000 feet MSL, the required runway is 3800 feet, again, without any error margin.

To take off from a 3500 foot runway, the aircraft has to weigh no more than about 210 tonnes at Sea Level. Again, this is a dry runway only.

At the same weight, it needs a 5000 foot runway to take off (Dry runway)

[Surya]

thats not enough - an article that says IL 76 or any other heavy lifter landed X number of times on a unpaved runway, supplying Y number of tons before the runway had to be maintained\repaired is what I am looking for.

One off or even a few landings I understand but I want to see some repeated sustained effort.

[amit]

^ Those were bought in an era when WEST was fighting imaginary ghosts of communism and India happened to be on the other side .
More importantly during the Soviet era we got most of those platforms at favorable terms and in most cases there was no western equivalent on sale. For instance even today Unkil wont sell anything in the league of a Tu-142M to India.

We bought the Mirages,Gnats and Vampires when we could .

Negi,

Boss fair point.

However, if we take this point "most cases there was no western equivalent on sale" then in this case the reverse seems to apply. Which is to say that "there is no Russian or European equivalent" to the C17.

Do note what Air Chief Marshal PV Naik said:

We need very heavy transport aircraft, the v hi-tech variety of the C-17 class.

It's pretty obvious that, at least the ACM doesn't think the Il76 is of the C17 class as he also said something else in the same statement which seems to have been missed. And that is:

The UN missions are probably going to increase so we need to take our people there, bring them back, which we do by chartering aircraft at the present moment. If Air Force had that capability, we could do that too. So projection of power over large distances in keeping with the country's aspirations is something we are definitely looking at.

So despite having Il76s in its inventory the IAF has to charter planes to send our jawans on UN missions. Why? Is it because the Il76 is too narrow to carry the equipment without which the jawans are toothless? I think that's a valid point to ponder, especially in light of the "We need... C17 class" quote from the ACM.

George has pointed out several times that even if we have a 60 ton lift capacity Il76 - the increase in capacity being the result of more powerful engines - we'd still be left with a plane which is too narrow to fit in a lot of the equipment that our troops need, like for eg, our MBTs.

There is no chatter about Ilyushin planning to develop a wide-bodied version of the Il76. And to think they'd go into the trouble and expense to do it for a 10 or maybe 20 plane order is rather laughable. Of course the caveat here is that they'd probably be happy to do so if the Indian government funds the effort as well as fund the shift of production facilities to Russia, something which is not happening due to lack of funds. Is this worth funding? And even assuming we do spend the $$$ (which surely run in the billion range), when would we likely get the new Il76? RFIs, unfortunately are not silver bullets and you only send one when you know that there's a realistic chance to getting a credible response, IMHO.

And also note that the Airbus transport will be of a 37 ton class, certainly not in the very heavy transport category.

One last point: The last and only time when India send an expeditionary force, the IPKF, it was able to transport it's then MBT the T72 to the frontline. Now if, say India were to decide to send a force somewhere, it would need to charter planes to send the current MBT to the frontline - neither the Arjun or T90 would fit in an Il76 unless it's fuselage is widened. I think that's a point worth considering when we take into account that whatever plane we buy today will be in service for the next 30 years at least.

The folks who run IAF are certainly not God but to think of them as ignoramuses is also rather stupid, IMO.

JMT, take it for what it's worth

[amit]

but let us at least accept the facts and be more informed.

Rohit,

I agree with you on this point. However, it would be nice if some other folks did the same - that would result in a good give and take discussion. (Please note I'm not including you in the some other category).

Also since you certainly know more about this aspect than me let me ask you this question in order to learn something new.

If, hypothetically, the IAF did want to land the C17 at the ALG mentioned, what would be the constraints?

a) Altitude?
b) Length of Runway?
c) Quality of the Runway?

If it's (a) then its a intractable problem, C17 would never be able to land there. But if it's either (b) or (c) or both then, as Kanson mentioned, if the IAF really wanted to land the C17, as it wanted in the case of An32, then it should be possible right? Of course, this assumes that there's enough flat land there to lengthen the runway.

Also, the point is if the C17 arrived at the ALG even half full, that would still be considerably more cargo carrying capability than that of a full load An32, right?

[negi]

You are quoting me out of context , my post was a reply to a specific post.

Today times have changed India is seen as a huge market for arms, there existed equivalent platforms to the ones in the list quoted by Hines in US stable but they were never up for sale for us , that is not the case anymore.

Where have I questioned the C-17 acquisition , I guess I made my point between pages 4-20 of this thread before you even started posting.

[amit]

Where have I questioned the C-17 acquisition , I guess I made my point between pages 4-20 of this thread before you even started posting.

Boss,

Apologies.

It wasn't my intention to say that you've questioned the proposed acquisition. You see I may not have posted between pages 4-20 (or whatever, I personally didn't note from which page I started posting) but I've made it a point to read every single post and I think I know fairly well what's the take on this of different posters.

In this particular case I just used your point as a prop to take forward the discussion/state my POV.

(After all you also didn't raise the RFI point either.)

I just wanted to point out that, at least the IAF thinks there is no equivalent plane available now. We may not like that but since they are the ones who will be flying the planes and planning for contingencies, I think their opinion matters more than ours.

And yes, a cool dude like you shouldn't let the heat of this thread get to you.

We're all here to discuss and learn, na?

[Gilles]

thats not enough - an article that says IL 76 or any other heavy lifter landed X number of times on a unpaved runway, supplying Y number of tons before the runway had to be maintained\repaired is what I am looking for.

One off or even a few landings I understand but I want to see some repeated sustained effort.

I do not even know why I bother to reply to a person like you. After reading this, you are going to say that the article does not specifically say that the runway was not repaired and you are going to ask me to provide proof that the whole airlift was done without needing runway repairs. Normal people would assume that if it was not mentioned, it was because it was not an issue. This is why I ignore you normally. But anyway, read on.....

http://www.af.mil/news/story.asp?id=123142202

3/31/2009 - THULE AIR BASE, Greenland (AFNS) -- Thule Air Base was the scene of an historic event of multinational cooperation between three countries that less than 20 years ago glared at each other across the Cold War's Iron Curtain.

American, Danish and Ukrainian air forces successfully completed Operation Brilliant Ice 2009 March 26 after transporting more than 140,000 gallons of fuel and 17 tons of supplies to the Danish military outpost, Station Nord, 600 miles northeast of here.

The operation, nicknamed "Cossacks on Ice," began March 9 and required 16 trips on a Ukrainian IL-76 Ilyushin aircraft to transport the supplies.

Although Operation Brilliant Ice is an annual operation, this year marks the first time Ukrainian air force strategic airlift provided the transportation from Thule to Station Nord and back. Thule was the base of operations for sustaining and maintaining the Ukrainian crews and aircraft.

"We have always supported the complex and impressive resupply operations to Station Nord," said Col. Tom Peppard, 821st Air Base Group commander, "but the addition of the Ukraine involvement made this year's operations even more incredible. We're proud to be part of such a partnership that would have been impossible only 20 years ago."

To check on the status of the operations and to commemorate the historic event, numerous delegates from Denmark and Ukraine visited Thule in mid-March.

"Ukraine is living up to our wildest expectations," said Brig. Gen. Max A.L.T. Nielsen, Denmark Tactical Air Command acting commander. "The crew set a record in lifting fuel in one day March 18, transporting (10,223 gallons) in one trip. If done by Denmark, it would have taken more than two flights on our C-130s. This in itself shows the advantages of Ukraine's strategic airlift."

The outpost exists for enforcement of sovereignty and scientific purposes, and five Danish service members are stationed there year round. The royal Danish air force is tasked with supplying Station Nord.

In past years, Denmark's Tactical Air Command conducted resupply operations with C-130 Hercules aircraft, but Denmark's support to the war on terrorism required changes.

"With Denmark's Tactical Air Command engaged in different operations in Afghanistan, we were close to being overtasked," General Nielsen said. "Through the cooperation between Denmark and Ukraine, we learned about their strategic airlift capabilities. That was how this partnership evolved."

The delegation also visited numerous organizations on Thule to learn about its missions and responsibilities during their stay.

"As always, the American hospitality at Thule is never ending. We are greatly enjoying the visit," General Nielsen said.

Just for your information, Station Nord is a 5,500 foot long gravel runway. Although the article states that it was the first time the Ukrainians did the annual airlift, it was not a first for the IL-76. Russian IL-76s have been doing it for several years, since around 2002 (Since the time the Danish C-130s that used to be used for this supply mission are busy in Iraq and Afghanistan)

Video of Russsian IL-76 landing at Station Nord in 2008 (one year before above article):



Here is a 2006 video of a Russian IL-76 landing at the same place (3 years before above article):

[youtube]7ENWi9ttcD0&feature=related[/youtube]

Here are Danish Air Force Posts about the same. Feel free to write to the Royal Danish Air Force to ask them how much damage the IL-76s did or did not do to their gravel runways.

http://forsvaret.dk/FTK/Nyt%20og%20Pres ... nNord.aspx

http://forsvaret.dk/FTK/Nyt%20og%20Pres ... A5et1.aspx

Here are the contact names, numbers and emails to ask your questions. Do not forget to post the replies on this Forum.

http://forsvaret.dk/FTK/Kontakt/Pressek ... fault.aspx

[Surya]

well I am an abnormal person - hope that makes you happy bwana


So 16 trips in about the same number of days. ok thats a start - and yes I will not assume that no runway work was carried out.

[Sanku]

There seems to a pattern here in that the Indian government of the day decides what it wants. RFI be damned.

The GoI has revamped it procurement policy in 2002-2003. Apart from geo-politics this is a single significant data point.

Its pointless to discuss how things were done before new rules were framed.

[Sanku]

Pretty impressive data points Gilles, so it turns out that not only are claims of C 17 unpaved airstrip not really true, the aircraft that it is true for is actually not being talked about.

[Viv S]

The C-17 can land at any unpaved runway that is long enough. The problem is that the combined effect of its high footprint (does not have enough wheels) and the heavy braking creates huge ruts in the unpaved surface, which soon requires heavy repairs.

You asked if any aircraft does the same thing. The IL-76 which has a maximum landing weight for unpaved runways of 135.5 tonnes spreads that weight over 20 wheels (6,8 tonnes per wheel on average). The C-17 which lands at 202 tonnes on unpaved runways, spreads its weight over 14 wheels (14.4 tonnes per wheel on average, over double the footprint of the Il-76). That is the origin of that problem. Which is why the planned Boeing C-17B was meant to have 4 extra wheels in a center landing gear.

Do you have figures on their respective wheelbases because the number of wheels itself doesn't give out a fair comparison. The C-130J exerts upto 13 tons per wheel but most would agree it can operate out of all airfields as the IL-76.

[Viv S]

Again the idea behind saying that it land on a 3000 ft. runway is to indicate the aircraft's short airfield performance. In real life the engineer detachment will not stop preparing the airfield after 3000 ft unless circumstances demand an urgent landing. Most fighter aircraft can pull 9Gs(some can go up to 11Gs FCS permitting), but that doesn't mean it will actually pull that in regular flight. The point I'm making is that the C-17 can be used to airlift an Arjun/T-90 to an ALG particularly in a higher altitude area while the IL-76 can't.

The ALGs I was able to find on GoogleEarth had long runways. Are they long enough? The only tables I found about C-17 landing performance made no mention of distance required above 6 or 7000 feet and the minimum runway was 7000 feet at that altitude I think. What length is required at 10,000 feet. What load can it take ?

Why dont the Il-76s fly to the ALGs? Are they not capable ?

But another factor is can the surface of the ALGs sustain the weight of the C-17? I guess we will know in a few days wont we ?

With regard to the altitude - that goes for all aircraft. The C-17 AFAIK was never marketed as being able to take off within 3500ft at an altitude of 7000ft. Most fighter aircraft for that matter, while marketed with significant STOL capabilities, wouldn't guarantee the same for high altitude airfields. And 3,500ft is the figure espoused by Boeing. The average length of the relevant ALGs is unknown(at least to me).

The IL-76s don't fly to ALGs for the simple reason that they haven't been required to do so yet. And that may well change in wartime.

[Viv S]

The IAF wants a plane that is available *now* . The touted "alternatives" are not available. Ergo, its only the C-17!

Simply untrue, repeating it a 1000 times is not going to cut it.

And IAF wants to carry more than Il 76 is passe.. how much more 10 grams? 100 grams? Forget Il 476, NEW Il 76 MF/MD can carry up to 60 tonnes.

They can carry upto 60 tonnes but because the floor space is limited much of that tonnage cannot be utilized.

So then you will say no IAF wants a cargo hold this big, but not not An 124 because its too big.

But no that wont do because it HAS to carry 77 tonnes. Unless you define your project to be exactly lik C 17 how can you buy it.

The question is why does IAF ONLY want a 77 tonne carrier (not a gram more or less) but that we can not ask because IAF wants it.

No the problem isn't that the An-124 is too big. Two factors here-

1. Its not in production and it will be a while before mass production is even achievable. The aircraft's future is not assured and even if produced, it may have a very short production run leading to valid concerns about after sales support.

2. The cost advantage doesn't apply to the An-124. Its acquisition cost is comparable (may be slightly lower) but its cost of operation(assuming its similar to the smaller C-5) ensures that the lifetime cost ends up about 50% higher than the C-17.

(3). Its rough field performance is still theoretical though I'll concede it may in fact have that capability.

If people think that interoperability means, being able to land at the same airstrip, I wont even waste my time with them. Its like talking to 2nd grader about calculus.

AFAIK IL-76s and An-124s don't just make stop-overs in Afghanistan they perform the same function as the C-17s and C-5s.

But, I (and I guess others as well) would be interested in what interoperability IYO entails. ??

[Viv S]

The side tracking is deliberate because there are simple questions

Does C 17 have a capability which is not present in ANY of the modern air lifters -- NO.

True but it does have a capability which isn't present in any modern air lifter in production i.e. airlifting a MBT.

Does C 17 production line which is about to be closed (If no IAF order) any different from other production lines -- NO

YES. The C-17 production line isn't going to be closed. They still have another 37 aircraft to deliver (Jan 2010) and production will carry on till September 2012 without IAF orders.

Defense Industry Daily

Can any one come with a magical requirement which will be met only at 77 tonnes but not more or less? -- No

Not at all. If the IL-76 were a wide body aircraft it should have been participating in a two-way competition with its PS-90A equipped variants. Also, the army's opinion with regard to its future armored strength should have been considered.

Is there a tearing hurry to get C 17s failing which IAF is doomed and cant take out 6 months for a RFI? -- NO

No tearing hurry. Its been three years and may well be four before an order is placed. Which isn't unreasonable compared to most orders placed in the past be they small arms (Tavor), aircraft (Su-30MKI) or submarines (Scorpene).

Sorry boys -- you want India to pay through its nose for gold plated stuff which can be done in much better ways. Good for you, dont expect any one else to believe that though.

The MoD and IAF seem to be pretty agreeable with regard to the C-17 purchase. The media's coverage hasn't raised any eyebrows either. And far from being critical, most defence commentators have welcomed the IAF's decision.

[Gilles]

[quote="Viv SDo you have figures on their respective wheelbases because the number of wheels itself doesn't give out a fair comparison. The C-130J exerts upto 13 tons per wheel but most would agree it can operate out of all airfields as the IL-76.[/quote]

I just provided a link to this document a few posts ago

http://www.tc.gc.ca/civilaviation/inter ... able_e.pdf

It provides the aircraft load ratings for most aircraft It give two lines of figures for each aircraft model. The higher weight is at Maximum Take off weight, the lower figure is at Maximum Zero Fuel Weight or wmpty weight , according to aircraft model (in Kilo Newton) One has to extrapolate to arrive at intermediate weights.

[Sanku]

Viv S, spare me the figures pulled out of your Musharraf. Real figures and references have been posted by Gilles and me and frankly in light of what ever has been posted, the less said about your figures the better.

Either get some references or stop polluting the threads with your dream world.