though old stuff, but interesting none the less,

http://www.nal.res.in/oldhome/pages/arupadhyacontriai.htm

Dr.Upadhya is one of the few specialists in the country in the multi-disciplinary field of Aeroelasticity. His major contributions to Aerospace research and development and industry, many of them as first in the country are listed below :

(i) Transonic buffet Testing of Launch Vehicle Models at NAL, Bangalore .

Transonic buffet is a serious problem for launch vehicles with bulbous nose and strap-on boosters. The problem is not amenable for easy mathematical modelling because of the complex nature of the unsteady, aerodynamic flow involving shack-boundary layer interaction and flow separation. Hence the problem was studied by aeroelastic modelling and testing in wind tunnel scaled aeroelastic models simulating the external aerodynamic shape and structural dynamic characteristics were designed and built. The model was supported internally on specially designed flexible spring—moments on a wing tunnel sting so as to simulate free-free dynamic behaviour of the vehicle. The model was instrumental and calibrated to measure dynamic bending moment distribution in the vehicle in its vibration modes due to aerodynamic buffet excitation in the wind tunnel. The wind tunnel tests in the transonic regime in the NAL 1.2 m transonic tunnel yielded valuable data on the dynamic structure to buffet and adequacy of structural design. Such models and tests were done for the first time in India for ASLV by Dr.Upadhya which were later adapted by NAL for PSLV and GSLV buffet testing. VSSC was very appreciative of the effort.

Earlier to this, Dr.Upadhya was involved as a member of the tests at NAL in the SLV-3 body divergence and fin-flutter modelling and testing.

Aeroelastic Design studies on LCA

Aeroelastic interactions played a major role in the design of LCA as it employs many advanced technologies such as carbon fibre composites in its airframe, digital fly-by-wire flight control systems, unstable and dynamic configurations etc. which cause interaction between aerodynamic, structural dynamics and control systems dynamics affecting loads, flutter, FCS stability and response etc. Dr.Upadhya ked a team of engineers which analysed these problems in a very detailed manner and gave valuable inputs for design and certification.

Maneuver Loads for structural design

Manueuver loads computations were done synthesising steady aerodynamics inputs from CFD Wind tunnel test group, Finite element model and mass data. Effort of aeroelastic differentiation on the air loads differentiation was taken into account. Hundreds of load cases were guaranteed correspond to cover points of load envelopes and during flight conditions out of the a few critical ones, from design point of view were selected for using new selection procedure based on weighting function approach for detail design/optimisation. Finally, elaborate design slate on aeroelastic efficiency on aerodynamic derivation were generated for use by control law design groups.

Aeroelasticty tailoring of CFC wing skins.

Aeroelastic losses in control effectiveness is very significant in combat aircraft. Attempts to decrease the losses leads to weight penalty. However, with composite skins, an opportunity to tailor the number of layups in the chosen films directions in the different regions of wing was available and this was effectively utilised in the structural optimisation process, thus meeting the weight targets and control requirement simultaneously.

Tests Analysis.

Analysis of structure control aerodynamic interactions became very important in LCA due to the reasons mentioned above. An integral ASE model was developed using component models from structural FE vibration analysis, unsteady aerodynamic Actuator dynamics, FCS dynamics etc. Detailed response calculations at the motion sensor locations were done in the frequency domain, determining structural mode participation in the response. Extensive parametric studies were conducted to get full envelopes of the gains and phase response. This data was used by the control law team for preliminary design of NFs. Such analysis was used for extrapolation or read across of data for tests to internal configurations.

Testing full scale flight for vibrations and structural control coupling evaluation.

Analytical prediction methods for these aero-servo elastic interactions have been developed by the team at ADA . However, they are not adequate for airworthiness certification. Specialised tests on the full aircraft are called for to asses the structure control coupling characteristics and take remedial action to suppress this coupling. Such specialised tests are Ground vibration Test and Structural coupling Tests for generation of relevant design data and alter for certification. These tests were successfully conducted on LCA by a team of ADA Scientists led by Dr.A.R.Upadhya.

The Ground Vibration Test (GVT) was conducted to evolve the modal vibration characteristics of the aircraft which formed the basis for all interactions with FCS and unsteady aerodynamics. This involved exciting the aircraft with electro-dynamic shakers located on wings, fuselage and fin, and acquisition and analysis of response data on the aircraft at nearly 250 locations using accelerometers. A state-of-the-art multi-input multi-output (MIMO) GVT system was used for this purpose. A novel technique of suspending the aircraft on rubber bunge cords from a rigid suspension rig to simulate free flight condition was used. Perhaps, for the first time in aircraft development, random excitation technique was used in testing. This saved valuable test-time and avoided fatigue damage. It also made possible extraction of all the modal data from a single test. The test results were extensively compared with analytical predictions of the team, showing good correlation.

The Structural Coupling Test (SCT) was conducted in two phases. The first phase(SCT1) involved ‘Aircraft Identification’ wherein the coupling of structural vibration response with the aircraft motion response as measured by the FCS sensors was characterised. This test generated data for the design of notch filters to be implemented in the Flight control Computer(FCC) to suppress undesirable response. After implementation of the notch filters in the FCC, the second phase of the test (SCT2) was conducted to verify that adequate gain and phase margins were represented at the structural mode frequencies. Both these tests involved excitation of the primary control surface actuators through the FCC using sweep sine excitation, and measurement of the frequency response characteristics of the aircraft motion sensor responses or the actuators demand signal from the FCC. In order to overcome a likely situation of poor signal to noise ratio in the actuator demand signal due to the presence of the notch filters, an innovative technique of profiling the excitation signal amplitude was used in the tests.

The highlights of the work are:

1. Conducted for the first time in the country perhaps only second or third in the world.

2. Tests done on a flight standard aircraft

3. Extensive and efficient coordination with several design groups involving airframe, FCS on-board and ground based systems.

4. Development of the computer controlled Ground Check-out System(GCS) for definition, execution and control of tests and on-line data analysis and display.

5. Ensuring safety of aircraft during tests using a specially developed Loads Monitoring System and FCS Health Monitoring

6. Extensive post-test data analysis and synthesis and correlation with computational predictions.

7. Provided all the data for the design of notch filters in the FCC

8. Confirmed adequacy of FCS margins.

The tests were also most essential from airworthiness point of view. The Expert Review Committee which reviewed the procedures and results specially complimented the team for their excellence of work in a difficult and challenging technical area. The efforts of the team has resulted not only in establishing facility for such large scale tests bug has generated expertise to asses vibration characteristics and structure control interactions for any complex flight vehicle with confidence. The techniques and facilities developed such as the Aircraft Suspension System, Random Excitation Technique, the Ground Checkout System and SCT techniques are innovative and unique and are perhaps the best in the world.

Well, I remember something about bugs found which prevented the Jerkules from used with SpecOps but strangely I cannot find anything. Looks like the bugs have been worked out since then. I stand corrected.

C-130J Military Transport Planes Deemed Unfit for War

Nov. 17, 2004

The C-130J tactical transport aircraft was supposed to be the U.S. Air Force’s state-of-the-art cargo plane to fly troops and supplies into dangerous areas.

The Air Force has 50 of them, but investigators now say all of the planes are unsafe. They are especially concerned about problems in the aircraft’s computers and missile defense systems. There were even reports of propellers breaking down and cracking in bad weather.

“Without your propeller, your aircraft’s not going to stay in the air,” said Eric Miller, senior defense investigator for the Project on Government Oversight.

The Pentagon’s inspector general in a 34-page report blamed the manufacturer, Lockheed Martin, for 33 deficiencies in the planes — planes that cost the Air Force $2.6 billion.

That came as no surprise to Ken Pedeleose, a Defense Department engineer who worked on the C-130J project. For years, he has fought with Lockheed and the Air Force. He told ABC News the C-130J plane is dangerous and a rip-off.

“I just couldn’t stand sitting back and watching what’s happened, knowing that I could’ve said something about it,” said Pedeleose, “and I didn’t.”

“One of the major ways we know that there’s problems with the aircraft is we’ve never delivered a completed one in 10 years,” he added.

The Maryland National Guard in Baltimore has eight of the planes. One of their primary missions is to fly into hostile areas such as Afghanistan and Iraq, but C-130J pilots in the unit have been limited to missions closer to home.

“They want to get this airplane into the fight,” said Col. Guy Walsh, commander of the Guard’s 175th Wing, but they can’t get into the fight until the plane is deemed safe.

“Safety is our number one concern,” Walsh said. “To make sure that when we go out there to accomplish the mission that we do it right, we do it right the first time, and we bring each of the crews back and our airplanes back.”

Improvements Being Made
Lockheed says improvements are being made. The company, in a written statement, said, “The statement [in the inspector general’s report] that the aircraft failed to meet operational requirements is not indicative of the C-130J’s current performance. The C-130J’s success was recently demonstrated during a procedures development evaluation, where the aircraft scored a 100% mission capable rate and a 100% mission effectiveness rate.”

The Air Force believes the planes can safely be flown in Iraq by the end of the year. Pedeleose says that would be reckless.

“If it is deployed in combat, you are putting people’s lives in danger,” he said. “And needlessly putting people’s lives in danger … there’s no reasons for it other than to prove the [Pentagon] inspector general’s office wrong in their report against the C-130J.”

A representative for the Department of Defense inspector general’s office told ABC News that operational testing of the C-130J, which is not scheduled until November 2005, will determine whether the plane will meet full operational requirements. Releasing the C-130J for deployment prior to operational testing, according to the inspector general’s office, is an Air Force decision.

The inspector general’s audit staff continues to monitor the Air Force’s compliance with the report recommendations. So far, they say the Air Force’s response is “responsive and positive in addressing the report recommendations.”

Despite eight years of problems with the plane, the Air Force plans to buy 67 more of them, spending $7 billion.

Said Pedeleose: “I think the Air Force and, in particular, the taxpayers have just gotten a very bad deal on the C-130J.”

ABC News’ John Cochran filed this report for World News Tonight

http://abcnews.go.com/WNT/Story?id=260411&page=1

This one? :dev2: 😀

It has nothing to do with need and preferences. In modern days, an Airforce does need heavier and more capable aircrafts and PAF is no exception. Why PAF is not after one (lets assume) it is because 1. They cant get a capable fighter from no where, not even from China. 2. They dont have resources to maintain such assets.

I dont agree with you,

1> Money speaks, so if they are willing to spell something for J11 or Rafale/Typhoon they can get that, remember Typhoon were offered to them and French are more than willing to sell anything.

2> Well Can be, quite can be, but they dont need TOT et al, so whenever new fighter comes you get a sort of team from that country assisting , again money matters.

Joey: i dont doubt your knowledge either but the problems thrown up by smaller processors and smaller memory footprints can be even more challenging to solve then those on the desktop PCs. Atleast for me. 🙂

nah, you see your not adding air borne laser in MKI, but adding a jamming pod which it is entitled to carry, I dont see any issue here. You need to remember your system is designed to carry such things from start.

Plus I’m not much knowledgable in all these than nick, Anythign about MKI ask him.

Im not denying that different vendors need to be involved. But it is much easier to work within the country then across countries. The issues that crop up are sometimes solved by compromising one parameter or the other.

Its not a matter of denying, the problem you said does not crops up in a plane developement, I cannot explain you properly but say for example Navy’s 10G network, when you have the kernell of a system you can do any modification you want to.

Plus you dont compromise one thing or another while adding system, that holds for software developement, and not adding existing hardward to a software that you have complete control over and designed to suit a partcular architecture chalked out which can support lot of other nodes and allow space for further expansion.

If your saying about working easier within country that I agree however your question about architectural issue becomes non-relevant what becomes relevant here question of how much TOT et al and nick has mentioned clearly that is layed out in more detail manner than we can think off in the DPP agreement, plus the core things are indian.

I mean c’mon each and every plane as per your logic would suffer problem like you said then which isnt exactly the case IIRC.

Good to see us finally back on the topic. Lets hope it doesn’t get derailed again.

I have asked for jf17 cockpit pics before as well lol.

We can discuss the core systems on another thread. As far as system integration in an open arch environment goes, im quite familiar with it and know what the issues are. Which is why i raise them.

Doesnt holds any waters, nick has already told you and hes much better know-howed in MKI system.
I have given you F22 integration and they comes from different vendors.

The DPP agreement includes full sources codes for MKI attests to, and as Nick said core system being Indian.

Add to the fact we are constantly upgrading it, new HADF pod, Astraa will be integrated, Link 2 datalink system et al.

Actually, id prefer the block 52 but thats another discussion 🙂

no way man, I’ll pick F16I anyday :p

Back to JF-17 related discussion.

Affirmative.

kaduna your talking like grapes are sour stuff as the same thing has backfired on you, The fact remains And nick has explained you dont know how system integration works in a open architecture system, and in MKI the most critical core systems are Indian.

How and which IP et al, nick might not give such detail, but there was once a nice article in csir about MKI’s avionics developement.

All Indian bird share many common things derived from MKI, anyways even F16I is build the same way around 😉 now dont say “i still prefer Block 52 over F16I because it comes from one vendor”.

IIRC, SINDEX exercise did exercised BVR tactics, IIRC singapore lacks airspace for proper training, thus they had struck a deal with GOI for their use of Indian airspace for training and IAF pilots would train them with some tactics in the exchange they will give us first hand total lok in their F16 IIRC.

OTOH, Kaduna, your point of MKI having problem due to integration is not correct, because you dont know how system itnegration happens in a open architecture system, nor are you aware of what source codes are needed for what and which we have and which we have not.

Plus you cannot say a bird’s is war tested means automatically better, I would like to see jf17 to come in some international exercises and perform.

Nick the good performance, need to be proven can be said for other birds as well, what matters is how it performs in exercises et al for a basic roundup view and also what kind of packages are included in jf17 and how many other birds are sharing such same things, like for EW of many IAF birds are same, proves the success and combat worthyness of that system.

by the way, JF17 has completed Phase 1 of developement, as per AFM and Phase 2 will begin till its IOC is expected by late 2008, correct right?