Teer
Rank 3 Registered User Join Date: May 2009
Posts: 602

Quote:
Originally Posted by matt
Thats the trouble, no offence but you say to a flyer that he can design a plane and suddenly you have a wish list as long as an elephants trunk with just as much time to achieve the same!

DRDO and ADA should go it alone without IAF involvement

Matt, thats simply not possible.

If they do that, even if the plane comes with a coffee machine, a TV with 100 channels, a seat massager etc and can out turn a gnat, the IAF will still reject it.

The only way possible, in the Indian context, is to involve the user at every stage, get them involved including with funding and project management, draw up a list of reasonable targets and then go for those. That way the user feels it is as much “their product” as the developers or manufacturers.

Teer if the IAF has caused the issues with the LCA then take them out of the loop.

I am all for the main stake holder being part of the loop but only if he is informed. If the stake hold does not understand basic engineering i.e. by way of its R&D or research wing then it needs to keep out.

Yes use the test pilots to fly the planes and ask for there requirements, but DRDO and ADA should not be dictated to by the Airforce on issues such as SHM (structural health monitoring), fatigue life cycles etc..

From what it understand the IAF has no one that understands all this and even if it did it would a redudent department because that is the whole point of the DRDO! it is the Defense ministries research wing , i.e. cousine to the IAF and IN and IA!

Matt, they will have to include what the IAF says as well. The IAF’s internal engineering is limited vis a vis the IN, but they do have a fair amount of access to OEMs & test crew. Other IAF officers are deputed to PSUs, to DRDO labs, plus there is the IAF’s own SDI. So a fair bit of technology expertise does exist, even if it is not R&D level.

So ADA & DRDO will have to do a fair bit of “negotiation” to come to an acceptable compromise.

That is actually why I am happy about the FGFA as well (PAK-FA), since its taking the high end Air Dominance etc role, with the MCA as support, the IAF will be more reasonable about what can be done with the MCA and in what timeframe.

Otherwise, they’d have asked for the Death Star packaged in a X-Wing, you get the idea.

Thats the trouble, no offence but you say to a flyer that he can design a plane and suddenly you have a wish list as long as an elephants trunk with just as much time to achieve the same!

DRDO and ADA should go it alone without IAF involvement

Thats exactly what is being done.

From ADA & IAF itself – ie the horses mouth, a formal launch will occur for actually developing the detailed TDs etc and achieving actual airframes, and for which GOI will commit the money once the MK2 program is achieved or sometime before that. Because that will require full organizational work.

But the basic design work & scoping to understand what the work is all about – can and is being done in parallel, today. Even if a 30-40% reduction in time for the same activities is achieved vis a vis when the MCA is formally launched – thats a huge thing.

When the LCA was launched, this took several years, as all sorts of consultants came and sold their “concepts” to the fledgling ADA and the IAF. Separating the wheat from the chaff was hard as there was very little inhouse capability to immediately determine what was what.

Today the capability exists. Eg if a vendor offers joint development of conventional sensors, the ADA knows outright that it needs flush sensors & will go for that instead, instead of a painful evaluation of pros and cons.

Also, detailed planning needs be done for what the LCA didnt require, but the MCA might. LPI sensors will be a key requirement for instance. So asking the LRDE, in advance, to “work towards this” with the current XBand AESA as a midway step is essential. As compared to telling the LRDE in 2014 that they require an advanced AESA etc.

All this does not require entire ADA to work on it either.

I was thinking more of the structure and airframe and not the sensors that is a different story and not something i feel knowledgable to comment on.

The MCA structure should have been completed and the testing at the bottom of the pyramid should have been conducted enough material testing to hopefully choose a decent composite system

The article says:

I have a n00b question. Would it take the entire LCA team to develop the Mk2 version?

The tone of the article seems to suggest that it would not. The article is dated May 2009. The development of Mk2 had been decided by then.

@Teer.
You are welcome.

Regards,
Ashish

I do not understand what the design team would still be doing working on the LCA, surely they would have finished 10 years ago when the production of the LCA started! its the ME’s who would be silly busy these days! the designers should be working on the MCA and finalising the concepts!

Prelim designs for the MCA should have already been finished!

I’ve seen the Keel Beam, and for that matter the RP B/h. Not seen the A380 T Box. Yes, they are indeed primary, sorry, my head was full of Wing.
Some points on the aforementioned items.
They are all out of the way from the stuff cfrp doesn’t like…Impact, UV, water ingress, wind resistance, lightning strike and in the case of a wing skin, the direct sunlight heating up the tank, significantly more so than an ally one. They are also structures which suffer very little torque or shear forces. BTW the A340 Keel Beam cracked, they redesigned it using series of carbon pins and IIRC they changed all the fasteners.
There are far too many unknowns in the all CFRP Civil aeroplane and far too may assumptions are being made. The market is over-riding the engineers and scientists. eg. the 787 has FAA approval and yet there are many significant tests not yet concluded. Change is not always progress.
Another fact, an airline spends 30% of it’s costs in maintaining it’s fleet. Because visual inspection of CFRP will not show the delams or sheared fasteners, the hangar time is going to double or treble. They will also have to buy expensive NDT kit, in addition to expensive repair kit. On the subject of repairs, once cfrp is damaged, it’s damaged forever, and will remain like an open wound for the ingress of moisture or anything else. A perfect repair can only be done back in the OEM. Bang goes the alleged savings in operating costs.

And lets not forget the crashworthiness and survivability. After the M/cr 737, toxic (Fume giving) substances were replaced. OK, lets make the WHOLE aeroplane out of a substance which when burns gives of fumes that will kill you in seconds. And, once it gets going it will take 6 or 7 times as long to put the fire out.
Have you ever seen a cfrp test? eg, an engine blade hits the containment case and it disappears into dust and fragments. Many people believe that a “Survivable” crash involving a cfrp fuselage will render the pax. trapped as the exits and window frames will severely fragment and splinter (Leaving extremely sharp protrusions) thus denying exit.

The pesent safety of flying has been brought about by a long period of extensive study into “Aftermath”. Changing the whole ball game in one hit is throwing away a great deal of knowledge gained. The aftermath will unfortunately have to happen again for true knowledge.

Lots of mixing apples and oranges in your post.

Your mixing fans with containment cases and presuming that the result will be the same for a larger structure with a lot lower energy?

The information you provide and the way you provide it, it seems you are on the outskirts of composite structures, looking in and not getting the whole picture.

What do you do?

If the CFRP is in a “Hot” area, they use BMI. That can stand 450 deg F. Main structures are not BMI..

Dont need to use BMI’s, and yes as mentioned before there are issues with regards to temperature but mostly for military aircraft which are expected to see hi temperatures in normal use (impact, being shot at etc etc) and some of them do use BMI’s PI’s etc..

However for civilian aircraft the requirements may not state that the structure needs to survive a fire, depending on what and where it is, it needs to survive long enough to allow the passangers to exit in a safe and controlled manner..

Not sure if it is scare mongering or lack of understanding.

There is no fuel bladder in a large commercial Jet. Fuel is in direct contact with the skins and spars and sealing ribs. As I said, you’d better pray that all the bolt tails have been PERFECTLY walnut-whipped.

Fair point but aircraft with composite skins d noses, wing spars have been flying or are being certified to fly what do you know that the authority and industry do not know?

The testing is ongoing as the damn things are being built, that’s why all 7 of the A400’s pre-production batch are all fundamentally different. And EIS is different from set 7. And there is already a mountain of Change notes on the EIS.

can you share your source?

787 is turning out to be the Nightmareliner, with spectacularly incorrect designs, choice of fasteners etc.

Source again please.. also Boeing may be having issues but this is not the same as the whole industry having trouble.

Aluminium went through the same issues back in the 50’s and 60’s with jet aircraft. Should they have gone back to metal and fabric constructions?

CFRP is cooked in an autoclave at 220F for about 6 hours. OK, the resin changes it’s structure slightly after the cook, may even get a few 10’s of degrees out of it. Take a look at the Airbus that caught fire on the runway a few years back, the empennage (CFRP) is a black soot pile.

temperatures for curing are usually a lot higher than 220F and times are usually in excess of 6 hours unless you talk of only working with 2 mm thick structures. HW Tg of over 120C is usually the order of the day. Dry Tg’s of over 170/190 are usually order of the day.

The lightning tests on A400, A350 and 787 are not looking too good at all. The large horizontal surface peppered with metal bolt tops is a serious problem. The h-stabs that have been carbon in the past contained no fuel. The lightning strikes they received left a concerning amount of surface burn.

Please provide source specially about issues on the A400 and the A350 as one is already flying (A400M) meaning it must have passed enough regs and A350 is probably still in the development phase.

Large and small military platforms have used CFRP for wings and main structures but they used a bond as the primary join and backed it up with fasteners. This is not good enough for large floppy airliner wings supporting pax. Military folk have a “Mummy!” handle and a parachute. The fighters in particular have a very stiff wing, usually 5 spars in it.
“Careful” is an understatement. But the pressure on industry to make a platform out of CFRP is immense. Pressure which is perhaps forcing the race.
The things I mentioned have not been solved, despite the best brains in the industry working on them. They will be solved, at massive weight and cosst penalties. The pax want’s flights to NY for £99 etc. Plastic airliners are not going to assist in this permanent price war.

Not been solved? Source? Also what makes you think it will be a massive weight and cost? if that was the case do you think the industry would even care about composites?

A lot of people still make a lot of money from ali structures if the potential for cost and weight savings did not exist people would not be looking into composites.

Would be interesting to see what sources you have to make such bold comments.

Bit to presumptious to say what Russia can and can not do and I think the gap in stealth is not really that large. All boils down to if the people working on it understand basic scientific principles (this is not the same as simple scientific principles).

The russians will build a 5th gen plane that best suites their needs and budget thats not the same as saying that they do not have the talent to produce the F-22.