Read the forum code of contact
By: - 29th September 2006 at 15:07 Permalink - Edited 1st January 1970 at 01:00
Guys I googled but due to lack of credible information posting here.
what are the absolute differences between these two and which one is better.http://video.google.com/videoplay?docid=-1994695142386399860 nice video on Su37.
There is no such thing as a Su-37. The only one in existence was bort number 711 - modified from a Su-35 by the addition of Thrust-Vectoring nozzles (TVC).
It has since crashed (after it reverted to being a 'plain old' Su-35 with the deletion of the TVC).
As for a comparison, there is no point - it would be meaningless.
The Su-37 (as was) was a single-seat 'super' Flanker - part of a batch of 12 + 3 such airframes, the development of which has ended.
The Su-30MKI is now in full production for the Indian AF, it is a tandem two-seater, with TVC nozzles, French, Indian & Russian avionics and a useful A2G capability that the Su-35/37 never posessed.
One was a limited-run, expermental exercise that led to a dead-end (although it could be resurrected) in service with no-one, the other is a maturing, multi-role, very capable fighter in service with India.
..........and, having said there was no point in comparing, I then proceeded to do so :diablo:
Ken
By: - 29th September 2006 at 15:12 Permalink - Edited 1st January 1970 at 01:00
Guys I googled but due to lack of credible information posting here.
what are the absolute differences between these two and which one is better.http://video.google.com/videoplay?docid=-1994695142386399860 nice video on Su37.
BTW - that clip is of the prototype Su-30MKI, NOT the Su-37!!
That's how good it is............. :D
Ken
By: - 29th September 2006 at 16:01 Permalink - Edited 1st January 1970 at 01:00
what was the old saying again -
" fly like a butterfly sting like a bee""
Only the MKI is no bee but a huge metal monster!!
By: - 29th September 2006 at 23:10 Permalink - Edited 1st January 1970 at 01:00
Structurally (not considering avionics) then which is a better build?
I once read somewhere that the Su-35/37 had significant modifications (for the better) to its structure compared to the Su-27/30 series. I am sorry I do not have the source with me, it was a report quoting a top guy from one of the Su design bureaus.
Could someone confirm or deny this?
By: - 29th September 2006 at 23:20 Permalink - Edited 1st January 1970 at 01:00
A SU-35 Multi Role would be a good fantasy if it had an F-18E like cockpit/avionics setup. :p
By: - 29th September 2006 at 23:28 Permalink - Edited 1st January 1970 at 01:00
Structurally (not considering avionics) then which is a better build?I once read somewhere that the Su-35/37 had significant modifications (for the better) to its structure compared to the Su-27/30 series. I am sorry I do not have the source with me, it was a report quoting a top guy from one of the Su design bureaus.
Could someone confirm or deny this?
Prototypes maybe!! but the actual production versions would be equally good simply because they are most likely going to be built at the same plants under the same scruitiny and quality control
By: - 30th September 2006 at 07:54 Permalink - Edited 1st January 1970 at 01:00
Thanks a lot Flanker man forclearing my doubts :D.
By: - 30th September 2006 at 14:04 Permalink - Edited 1st January 1970 at 01:00
The Su-30MKI features composite materials as well AFAIK and is not a complete "metal monster". The Su-37 was a single piece a modified Su-35, but it does not only included the AL-31FU TVC engines but also a non moveable throttle, side stick an seat inclined by 30° and french LCDs and HuD, as well as the N-011M PESA instead of the N-011 MSA used by the Su-35 and LINS+GPS. Some sources report about ELINT/SIGINT equipement for the Su-37 demonstrator. In fact the aircraft was reengined with conventionel AL-31F in 2000 and all non russian systems were removed and replaced by russian ones. Additionally the aircraft received an improved FBW system which increased the aircrafts agility without TVC.
The Su-37 contributed technologies for the Su-30MKI like the N-011M and the AL-31FP are finally a further developement of the AL-31FU.
BTW the Su-35 was as multirole capable as the Su-30MKI and also featured an rearward looking radar. If the Su-35 would enter production a lot of newer technologies would be integrated. The Su-30MKI however is a customized version including a lot of non russian avionics.
Sukhoi is now concentrating on the Su-27M2 aka Su-35(BM).
By: - 30th September 2006 at 14:07 Permalink - Edited 1st January 1970 at 01:00
As many have pointed out this is a pointless exercise, but on the other hand a comparison between the proposed Su-35BM and the MKI might be valid.
By: - 30th September 2006 at 15:16 Permalink - Edited 1st January 1970 at 01:00
The Su-30MKI features composite materials as well AFAIK and is not a complete "metal monster". The Su-37 was a single piece a modified Su-35, but it does not only included the AL-31FU TVC engines but also a non moveable throttle, side stick an seat inclined by 30° and french LCDs and HuD, as well as the N-011M PESA instead of the N-011 MSA used by the Su-35 and LINS+GPS. Some sources report about ELINT/SIGINT equipement for the Su-37 demonstrator. In fact the aircraft was reengined with conventionel AL-31F in 2000 and all non russian systems were removed and replaced by russian ones. Additionally the aircraft received an improved FBW system which increased the aircrafts agility without TVC.The Su-37 contributed technologies for the Su-30MKI like the N-011M and the AL-31FP are finally a further developement of the AL-31FU.
BTW the Su-35 was as multirole capable as the Su-30MKI and also featured an rearward looking radar. If the Su-35 would enter production a lot of newer technologies would be integrated. The Su-30MKI however is a customized version including a lot of non russian avionics.
Sukhoi is now concentrating on the Su-27M2 aka Su-35(BM).
With 90% of the LCA composite, the MKI may also receive some more significant amounts of composite material for weight/ RCS reduction etc..
http://www.bharat-rakshak.com/IAF/Info/11BRD.html
Typos corrected:
Concealed in a discreet corner is a specialist section working on composite materials for the MiG aircraft. With carbon glass as the ingredients, the BRD team has developed composite exteriors for the wings and fins of the aircraft to replace heavier alloys and metals, thereby reducing in considers (considerable) amount weight of the aircraft and in the process, add(ing) tremendously to its speed and manoeuvrability.
By: - 30th September 2006 at 15:36 Permalink - Edited 1st January 1970 at 01:00
Nick how is the composite going into the LCA ?? Is it the honeycomb type setup which we see or is it a monolithic type setup ?? for the fuesalage that is!!
By: - 30th September 2006 at 16:37 Permalink - Edited 1st January 1970 at 01:00
Nick how is the composite going into the LCA ?? Is it the honeycomb type setup which we see or is it a monolithic type setup ?? for the fuesalage that is!!
If I remember correctly, its a combination of both...this is a pretty old article from 5 years back..
Dreams lighten in LCA
Sqn. Ldr. B.G. PrakashAdvanced composite units at NAL and HAL were established. Both have been instrumental in supporting HANSA, SARAS and the LCA. Prahlad says that bridging a technological gap - as in handling the composites - is more important than satisfying the design aspects. Assemblies with fasteners, bolts, rivets get replaced by monolithic composite components. The spin off is easily absorbable in space launch vehicles and guided missiles, where reusability and pilot's lives are not issues.
Significant Achievement
The use of composites results in a 40 per cent reduction in the total number of parts: For instance, 3,000 parts in a metallic design would come down to 1,800 parts in a composite design. The number of fasteners has been reduced to half in the composite structure from 10,000 in the metallic frame. The composite design helped to avoid about 2,000 holes being drilled into the airframe. Though the weight comes down by 21 per cent, the most interesting prediction is the time it will take to assemble the LCA -- the airframe that takes 11 months to build can be done in seven months using composites.
Involvement of British Aerospace
A component that has curvature, bend and sharp edges may look easy to be formed with composites. But its strength and stress-bearing capacity at certain points is difficult to measure and to improve upon. Tooling design is the most critical requirement in composite technology. The skin of the LCA measures 3 mm at its thickest with the average thickness varying between 2.4 to 2.7 mm. The skin needs to bear a force of 100 Newton per mm. What the designers initially achieved was just 40 N/mm. With some improvements it reached 60 N/mm. Interaction with BAe offered some solutions. BAe is reported to have achieved 160 to 180 N/mm which was a challenge. It came to light only later that they were working with skin thickness of 6 mm. This was a lesson well learnt when composites were used in the bulkhead and stiffener underneath the skin.
T - Pull
The T-Pull problem was another headache for the designers. T-pull occurs at skin and stiffener edge. It includes two forces: One force which acts perpendicular to a surface is referred to as 'sigma z'. The inter-lamination shear stress the trme to assemble the LCA - the airframe that takes along the surface is the other. The flat top of a T-joint meshes with the surface of a composite panel. Adhesives hold them together. The 'leg' of the T joins the flat top not in a perfect mesh - but creates a triangular void at the junction. This is termed as the Bermuda Triangle. Forces tend to pull the leg away from the top; the initial design could withstand only 40 N/mm. An innovative introduction of a thin composite interface strip between the flat top of T and the surface improved the strength dramatically to 60 N/mm. From a basic design scheme it graduated into padded configuration and overlay configuration. Failure was expected at the joints - which did not happen.
On the fuel tank floor, horizontal and longitudinal stiffeners cross each other. At the point of crossing, the longitudinal members are cut out to allow the breadth-wise members to pass through. This process is intricate and special tooling was necessary. Stiffeners join the surface in T-joint and need to be perpendicular to the surface - at exactly 90 degrees!
Research and analysis are continuing to make the T-joint stronger. Adhesives and reinforcement are used to fill the void. Flex cores are used which not only look simple but also elegant. Stitches to bind the flat top of the T to the surface is another method. The recommendations of BAe helped and further progress is foreseen. A 'duct dividing wall' made of composites, which reduces the number of parts and fasteners, is another indigenous effort. It was conceived against existing norms. Complex tool is developed to work on an area measuring 3 m by 1 5 m made of composite. Baffle frame stiffener in fuel tank needs precision engineering.
Air Duct
The Air Duct is a monolithic piece that needs stiffeners. Generally stiffeners protrude outward or inward depending on the component. But the surface of air duct is to be smooth and protrusion of stiffeners cannot be outward lest it obstruct free airflow. So stiffeners are embedded and internal. According to Simha the consultant, one of the 'two best parts' designed is used where the air duct enters the fuselage, with four external and two internal stiffeners, which replaces nearly 30 metallic components. A conventional design could have been used. In the conventional sandwich design, two thin skins called face sheets of 0.3 mm to 1.5 mm thickness are separated by honeycomb struts made of aramid based nomex. The separated space of 10 mm to 20 mm is mostly hollow. Sandwich panels are used in under carriage door, hatches or panel covering the armament bay. Repeated failure was encountered at the inner skin of the air intake with the sandwich design, using metal or composite adopted until then. The other best part is the Y-joint in the floor of the fuel tank with longitudinal stiffeners along the body.
Y - Joint
The Y-Joint is an innovation in the airframe of the LCA where the air duct joins the floor of the fuel tank. Centre fuselage holds the fuel tank which is 2.5 m long. This part needs to handle hook stress and bending stress with the skin being 2.4 mm thick. A monolithic composite part that replaces several metallic pieces was developed. It merges with a counterpart at the bottom, which contains the fuel tank floor. Prevention of fuel leakage is of prime importance. Simha conceived of a small extension at the edge of the top piece, in a new design, which had to mesh with a similar receptacle in the bottom part in a Y-shaped joint. One arm of the Y runs to a length of 1.75 m along the fuel tank floor. No one was sure that it could be manufactured to required specifications. NAL helped. With stiffeners both inside and on the external surface, the secondary bonding technique was successfully used to a length of 1.75 m. The scientist who made this says: "One learns from nature. Branches of trees join the trunk usually in a Y-joint. It must be naturally strong."
Fin and Torque Shaft
The fin for the LCA is a monolithic honeycomb piece. No other manufacturer is known to have made fins out of a single piece. The torque shaft for actuating the rudder is a challenge. It is built on additive process. The cost of manufacture reduces by 80 per cent from Rs 2.5 million in this process. This is contrary to a subtractive or deductive method normally adopted in advanced countries, when the shaft is carved out of a block of titanium alloy by a computerized numerically controlled machine. A 'nose' for the rudder is added by 'squeeze' riveting.
LCA has hats
Yet another innovative design is stiffener of hat section. It has a cross-section that resembles a hat in sequences, it endured the tests and worked well. A honeycomb sandwich piece measuring 400 mm in breadth was not reflecting the required strength to withstand shear forces. Other manufacturers have used similar designs. Within the breadth of 400 mm a hat like cross-section, six or seven in number, successively linked in sequence in the stiffener, is tried in the design. In fact about 30 per cent of the composite material is carved out from the original strip. Hollow portions are created. Yet the design proved capable of withstanding larger shearing forces. It is an optimisation of shape. Engineers use Finite Element Analysis in optimising. FEA computer software are available. Now, an engineer can develop new software based on this design. Autolay -- the software used by designers in the project -- is fondly mentioned.
Section 5435 and 8385
Composites are used in the inner skin at air intake on section 5435 of the front fuselage, at section 8385 of the rear fuselage and at the external skin of rear fuselage. The policy statement stipulates that small cutouts in the airframe are to be minimised; only large cut outs for access are acceptable. Where the straight stiffeners did not provide the required strength, flanged reinforcements were successfully tried. Benefits accrued in achieving improved buckling factor and consequently effected manageable stress concentration.
Lightning Strikes
When lightning strikes the LCA, four metal longerons stretching from end to end, afford protection. In addition, all the panels are provided with copper mesh. One out of five is 'bonding' bolt with gaskets to handle Electr-Magnetic Interference. Aluminum foils cover bolt heads while the fuel tank is taken care of with isolation and grounding.
Corrugated Composite and Test
Some components are of sheets that taper down from a thickness of 9 mm to 3 mm. Obviously, the lamination should dwindle without losing strength. A corrugated finish, which is meticulously achieved, is used. NAL has the only Non-Destructive Test facility in India using ultrasonic tests with frequency varying from 1 to 10 megahertz to test composites. It is needed at many stages in development. Result is in the form of colour images and is analyzed.
Indian Institute of Technology, Powai is involved in providing test boxes, which replace a few test panels. Ultrasonic based testing is necessary on composite surface, which does not show cracks but can have de-laminated layers. Dent shows up on composites though the design allows for barely visible damage to the skin, which may not grow. Moisture is absorbed by composite but the design takes this into consideration. A portable ultrasonic test gear is under development, which can be used in field formations.
SARAS is Thinner
The passenger aircraft under development, SARAS, has control surface that uses composite sheet of 0.6 mm thickness. Squeeze riveting used here is more sophisticated. Technology usable on a sheet with 3 mm thickness cannot be directly adopted.
Appropriate Technology
Plaster of paris is used to make moulds on which composite sheets of the required thickness including the taper are shaped. Surface of the mould needs to be absolutely plane, which is provided by smoothly machined granite tabletops on the workbench. Templates support the plaster block on both sides. The compound solidifies by normal sunlight. To prevent shrinking, solidifying compound from losing its surface grip on the template, screw and nut are inserted on the template. The nut acts as locking nut. Depending on the complexity, the number of screw holes increase. Appropriate technology is in use in the most sophisticated aircraft that this country has seen.
From a level of non-use, composites now form nearly half of the airframe, which carries 30 per cent of the total weight of the aircraft. At times, wealth of information gets poverty of attention - more so with the LCA. May the will of each Indian fly with it!
By: - 30th September 2006 at 17:24 Permalink - Edited 1st January 1970 at 01:00
And do you have the key breakdowns of which areas were Monoliths and which honeycomb?? and wether a private comp. ( or a floated venture) is doing the work . The reason why i ask is because i am new york and we had a very good chat session over lunch a few days back where some very informed members were saying that boeing for its future PROJECT YELLOWSTONE aircraft productions might be interested to either invest in india or china for a far greater portion of the work . Right now the schedule Boeing works on is very tight and they want very very experienced companies who can guarantee a solid and experienced design team , guarantee quick ramp up and have a history that they can trust such as KHI , alenia etc etc but given a decade or so of partnership these doubts can be aliviated .
Posts: 682
By: joey - 29th September 2006 at 13:12
Guys I googled but due to lack of credible information posting here.
what are the absolute differences between these two and which one is better.
http://video.google.com/videoplay?docid=-1994695142386399860 nice video on Su37.