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    Μilitary Questions & Answers

    nomadski
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    Post  nomadski on Fri Oct 04, 2019 12:51 pm

    The Yanks have converted F15 to low RCS with internal bay payload. Can Russia / China do the same with older metal planes, they have or sold? How did they do it? Nano paint? Composite panels stuck to original skin? Or new replacement composite skin panels? Can you guess?  Best solution is replacement panels. Including internal coated shaped panels. Can these be made and sold to different country to change to stealthy airforce? Iranians made coating of carbon nano - tubes also to stealth in some frequency of radar. If plane radar also works in this frequency then jamming by enemy does not reveal plane either. Imagine ordinary Chinese J7 jet with stealth! With low RCS external payload.

    https://youtu.be/Kn6nx_GGERQ

    I think that reducing RCS on a plane is useful to a point. Beyond which we have diminishing returns. That is we get reduction to a point, but never to zero. At very high expense. So high that it affects the number of planes we can produce. As long as the plane RCS is reduced enough to make it look much smaller, then jamming and decoys provide a more cost effective way of making plane hard to hit with radar guided weapons. And that is all  we want. And we achieve it at fraction of cost.

    Older jets can be given new life in this way. Using a combination of paints and shaped composite panels in some places, together with easy replacement of some parts, such as pilot helmet and ejection seat, now of composite materials. The radar cross section of modern jets can never be below a minimum undetectable value for many reasons. Internal bay on opening gives away position. The engine exhaust from rear is metal. And pilot face can not be covered, and is at least as big as pigeon on radar!
    nomadski
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    Post  nomadski on Mon Oct 21, 2019 9:49 pm


    In 2020, sanction against Iran will end. This means Iran can import military hardware and export also. Regarding the Iranians interest in developing domestic fighter jets, does anyone know if Russia manufacture a suitable turbofan for Iran 's new yasin light fighter / trainer? What size engine would fit? Can there be licenced production of this engine in Iran? What engine would be best suited?
    GarryB
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    Post  GarryB on Tue Oct 22, 2019 9:22 am

    Thanks for reply. Agree about needing fragments. But what size or weight or numbers?

    Different structures require different sizes and weights... note with the investigation into the BUK shootdown incident in the Ukraine the early model BUKs have different size and shape fragments from the newer models.

    Any choice is going to be a compromise where it is going to be more effective against some targets than it is with others... you need to decide what the primary target is and make the design flexible enough to be able to deal with other types as well.

    Patriot is a good example of a missile designed to bring down manned aircraft by shredding the structure with fragments... its problem in Desert Storm was that when the target is a modified Scud missile moving at a vastly higher speed than the aircraft it was designed to intercept resulted in the missile going for centre mass, but the fusing and speed of the target meant those fragments were hitting the rear of the target. Even if the target was a manned aircraft at mach 7 the patriot would still have destroyed a manned aircraft by essentially shredding the rear portion which most likely would have been the engines... destroy the engines on a level flying high speed aircraft and it will break up and be destroyed. The problem in this case is that by the time of the interception a mach 7 scud is falling ballisticly and its engines are not running so punching thousands of holes through them makes no difference at all to the speed or direction of the already falling object.

    A missile designed to hit such targets like the S-300 families would have targeted the nose of the missile and most likely exploded the warhead... completely destroying the threat and neutralising it completely.

    Another problem for the Patriot was that the Scuds were not being used as they were intended either... the greater range meant they were coming in at speeds they were not designed for so in many cases they were in the process of breaking up anyway, and of course patriot being what it was naturally aimed itself at the biggest parts.... the engines and now empty fuel tanks... leaving the warheads to hit the ground and do their damage.

    The purpose of 30mm Soviet and Russian CIWS on ships is to fire as many HE rounds at the target as quickly as they can in an effort to set off the warhead, which totally eliminates the target as a ballistic threat.

    Are Russian warheads in AA missile still the old soviet types?

    As shown in the BUK case the designs are upgraded all the time. AAMs often have specialised warheads designed to cut structures like wings or tails off rather than punch small holes.

    I don't think we can simply say, it is not armoured. Because too heavy. About blast, this only important for direct or near impact. Since size of warhead in AA is relatively small.

    HE rounds spread the damage beyond the impact point... small calibre rounds like rifle calibre and HMG calibres can be rather weak because their small light projectile size limits how much HE you can pack in so in effect they become and more like frangible rounds that penetrate and break up and spread damage with momentum rather than HE blast damage, but heavier, larger calibre rounds can be very effective in increasing damage or hit probability with air burst and AHEAD type rounds.

    Can not rely on blast effect.

    Most aircraft parts are under stress simply because the aircraft are in the air... blast effect can do all different kinds of hidden damage to aircraft and should not be ignored. Obviously at high altitude blast is much less effective in the very thin air, but at low altitudes blast can shatter rotor blades on a helo and bring it down without doing any damage to the aircraft itself or its engines.

    Also fragmenting warhead with large radius gives more choice as to type of proximity fuse. Large frag radius more deadly than blast.

    The most effective HE round is the one that penetrates the targets skin before exploding. Getting a direct hit makes everything else more effective.
    To get a large blast radius you need bigger heavier fragments that will not be accelerated to the same high speeds smaller lighter fragments are, but will retain speed better through the air. The problem there is that with small targets like cruise missiles with heavier larger fragments there will be much fewer of them which means fewer hits or perhaps no hits even if the missile gets close to the targets. Getting an nice even distribution of fragments in all different directions is hard enough with smaller fragments offering better coverage over shorter distances.

    Agree about thickness needed to act as RAM.  And we know what material used. So another way to estimate thickness. Good idea.  The weight and shape of internal component can be accurately worked out by looking at manufacturer using similar components in earlier model. Unlikely to be very different. Cost too high.

    The whole point of a from scratch stealth design is to shape the aircraft so that radar waves that hit its surface are deflected away and not reflected right back at the source of the original beam. Deflection means redirecting... we are talking mirrors and not clear glass here.

    Unless you can make the entire aircraft out of glass then radar transparent materials are useless... the pointed nose of a fighter jet is both more aerodynamic and more stealthy than a radar invisible nose cone that allows radar waves to enter and hit the radar dish inside it... which is a big flat surface area reflecting radar signals right back.

    The Soviets actually made a glass aircraft during WWII and it was actually very effective, but with use cracks appeared and ruined the effect.

    The idea with stealth design as I said is to design something that is a good aerodynamic and stealthy shape and then go over areas with peak return spots and put RAM and reshape the design so it becomes less of a hotspot.

    Basically to convert an existing type you do the second part but it means you can never get it to the stealthy level because it is governed by the laws of diminished returns.

    What I mean is that I could take a design like a Bear and do all sorts of things to it to reduce its RCS... radar transparent engine blades and various other changes that might take its RCS from 200m square to 20m square for 50 million dollars. Reshaping and new materials and other minor changes would be cost effective and dramatically reduce the RCS. The problem is to take that upgraded aircraft and get more results is 100 times harder and 100 times more expensive and much much less effective.... so the next upgrade to take it down to a 10m square target might cost half a billion dollars, and to halve it to 5m square metres might cost 5 trillion or it simply might not be possible.

    The point is that if you started from scratch with a stealthy base design the same rules apply so starting with an aircraft that is a flying wing and already only has a 10m square RCS then spending 50 million dollars on materials and RAM and making the bits more stealthy to drop down to 5m square will be part of the design and equally getting it down to 1 square metres or less might be possible too but it is going to be expensive... not just to achieve, but to maintain and operate... you might have trouble building the aircraft to that level of precision to get that level of stealth.

    Keep in mind that about 70 years ago in the 1950s making MiG-15s required tolerances of 5mm or better to ensure a flyable aircraft... today for stealth you need build precision much better than that.

    About laser guided AA missile, then Russia in good position to manufacture new types. Since radar and IR becoming less effective against stealthy plane. Leading edge of F35 cooled. So IR head on shot more difficult.

    Everything has a temperature... an imaging sensor can detect cold objects just as easily as very hot ones... being cold wont protect you from IIR guided weapons.

    Lastly you did not mention conversion of existing AA missiles by jacket or coatings. I said this originally as a way of reducing the RCS of plane carrying them externally, before being fired.

    Externally carried ordinance is never going to be stealthy... even conformal mounts means that externally carried weapons will create reflections over the lower surface of the aircraft that can reflect signals that can be detected...

    External weapons would be a RCS nightmare.

    Also for this purpose the AA missile could be carried inside composite RAM tubes. But a coating that fragments  while in flight makes design easier as resin used burns up at high temp Mach 4 flight. If coating burns and create plasma, even better more stealthy to RADAR!

    Internal carriage is still much more effective and stealthy... perhaps a pod in a weapon bay the forms the lower surface of the aircraft that can be lowered to launch weapons inside the pod and then retracted back in to the aircraft to make it stealthy when not in use could work, but this resin coming off your missiles in flight sounds like an ingestion issue waiting to happen... with internally mounted weapons pods there would be no need for RAM coatings.

    The Yanks have converted F15 to low RCS with internal bay payload.

    The Yanks also said the F-35 would be an affordable aircraft that could replace all existing types.

    The F-15 could be made reduced RCS, but certainly not Low RCS or anything like actually stealthy... and an internal payload bay shows you what the country with the most experience with stealth thinks of conformal weapon carriage... the F-15 already had conformal missile points for Sparrow missiles...

    Can Russia / China do the same with older metal planes, they have or sold? How did they do it? Nano paint? Composite panels stuck to original skin? Or new replacement composite skin panels? Can you guess?  Best solution is replacement panels. Including internal coated shaped panels. Can these be made and sold to different country to change to stealthy airforce? Iranians made coating of carbon nano - tubes also to stealth in some frequency of radar. If plane radar also works in this frequency then jamming by enemy does not reveal plane either. Imagine ordinary Chinese J7 jet with stealth! With low RCS external payload.

    Lets be clear... an all stealth aircraft fleet is pointless and expensive and not needed.

    Stealth is needed to penetrate and defeat IADS, but once they are damaged then much simpler and much cheaper aircraft that are not stealthy that carry a lot of ordinance externally like F-16 and F-15 aircraft of old are much more valuable platforms than having half arsed stealth wannabes.

    Making the Super Hornet more stealthy made it slightly less of a RCS light house but massively increased purchase price and operational costs and reduced range and performance in several important regards.

    The Su-35 and MiG-35 are fine and they don't need to make them more stealthy it would just be a waste of money and resources.

    A couple of stealth types with some solid 4th gen aircraft to support them is a vastly better and much more cost effective solution than making everything wanderwaffle that you can't afford in meaningful numbers.

    I think that reducing RCS on a plane is useful to a point. Beyond which we have diminishing returns. That is we get reduction to a point, but never to zero. At very high expense. So high that it affects the number of planes we can produce. As long as the plane RCS is reduced enough to make it look much smaller, then jamming and decoys provide a more cost effective way of making plane hard to hit with radar guided weapons. And that is all  we want. And we achieve it at fraction of cost.

    That is exactly right. You can piss away an enormous fortune with all stealth... but look at the design of the F-35... for the first missions in full stealth mode they have very limited payload capacity. When the enemy is beaten because you took out his airforce and most of his major SAMs and his comms and HQs then you can concentrate on wiping out his armed forces... ie tanks and navy... and for that role the F-35 has external stores... it stops being stealthy.... IT DOESN'T GET ANY CHEAPER THOUGH.

    They could have saved an enormous fortune by saying... well instead of 1,500 F-22s which turned out to be so expensive we made less than 200, and instead of the grandiose plans for 3,500 F-35s to replace everything else we have in service for 1.5 trillion dollars we could have the best of both worlds and have say 400 F-35 stealth fighters that can penetrate and rip up an air defence system and then use upgraded 4th gen aircraft to wipe out the armed force of that third world country we invaded this time.

    Their problem is that the air defence network of Serbia survived all their attention for months... the Russians can actually fight back in terms that can really hurt us... if we need to take 70 days with the Russian air defences then our airfields and our cities and harbours are going to get hammered and we are going to lose a lot of aircraft.

    They think the F-35 will do the job but it doesn't even live up to their expectations let alone what is actually needed.

    The best thing about the F-35 is that it is going to sponge up a lot of funds that could be spent on things that could actually make a difference, or make life better in the west... 1.5 trillion would fix a lot of roads and bridges and build a lot of parks in the US...

    Older jets can be given new life in this way. Using a combination of paints and shaped composite panels in some places, together with easy replacement of some parts, such as pilot helmet and ejection seat, now of composite materials. The radar cross section of modern jets can never be below a minimum undetectable value for many reasons. Internal bay on opening gives away position. The engine exhaust from rear is metal. And pilot face can not be covered, and is at least as big as pigeon on radar!

    Stealth is like camouflage... there is no such thing as completely invisible, but then most things benefit from not being obvious or easy to spot and identify.

    Compromising the entire design so it can't be seen makes little sense if it can now not perform its job.


    Last edited by GarryB on Fri Oct 25, 2019 10:31 am; edited 1 time in total
    nomadski
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    Post  nomadski on Thu Oct 24, 2019 10:04 am

    Agree about flexible warheads on AA missiles. I think there are anti - Tank warheads that operate in two modes. Blast and penetration. I also like idea of post penetration delayed action fragments. You can achieve a lot more with  this in confined spaces.

    Regarding the relative cost / benefit of conversion of existing aircraft to low RCS, I am afraid I could not answer that. I am not radar engineer or material scientist. But if the experts read this, then they can do tests. But what I can say, is that only the frontal area and leading edges of old aircraft may need to be converted. For low RCS frontal attack.

    Regarding cooled leading edges of  F35. I suspect that cooling of body parts will be controlled to that of surrounding or background temperature. So IR seekers will have difficulty still. I thought about evaporative cooling of missiles and UAV on approach to target.

    I do not see why an aircraft can be low RCS, but missile can not be. Internal payload increases the aircraft cross section and makes it less efficient.  The missile will always have smaller cross section than internal bay with mechanisms for lowering and operating and ejecting. Also a frangible coating only operates when missile skin gets very hot. Well away from aircraft. But I think actual test will provide answer. A shaped triangular or diamond shaped AA missile, will not need frangible coatings.

    Agree about needing limited number of very low RCS planes at higher costs for specific jobs. Such as SEAD . But also refuelling UAV Tankers now being designed. This was weak point in air war. The huge clumsy air Tankers.

    About point I made about Iran purchasing Russian jet engines. I would like a reply if possible. My idea is that sooner or later Iran will manufacture turbojet. And it will start selling planes and being a competitor. But if there is a joint venture, then the path to success is shorter for Iran. And for Russia it will mean sharing in profits of new more cost effective fighters / trainers. The Europeans shared the load. And rewards. Why not Iran / Russia or China?
    GarryB
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    Post  GarryB on Thu Oct 24, 2019 12:42 pm

    I think there are anti - Tank warheads that operate in two modes. Blast and penetration. I also like idea of post penetration delayed action fragments. You can achieve a lot more with  this in confined spaces.

    A round like a HESH can kill crew and seriously damage even heavily armoured tanks without penetrating, but an APHE is vastly more effective than just AP.

    With a vehicle like a BTR-60 most large calibre AP rounds or HEAT rounds go straight through so as long as you are not in the path you might survive OK... with an APHE round where the round explodes inside the vehicle pretty much everyone dies.

    The Vikhr ATGM actually has a switch on the launch control panel in a Ka-50 and Ka-52 that sets the missile to anti armour or anti soft target... ie anti MBT or anti everything else.

    It is rather easy to visualise... a HEAT warhead has a fuse at the rear centre and then basically a HE warhead that looks like someone has pushed a wine bottle in to its front and lined that surface with a metal cone. The warhead for Vikhr basically adds fragmentation material around the sides and rear of the warhead, and an extra fuse at the front or in the centre. That way before launch if the switch is in anti tank mode the rear fuse is activated... fragments will still be directed sideways, but the main blast will be forwards in a plasma stream made up of that metal liner in a superheated plasma form like a blow torch. If the switch is set for soft targets then the centre fuse detonates the charge and the HEAT warhead blows up like a HE bomb without the armour penetrating beam forming properly, so the blast would be more spherical and even than the focused beam of the Armour piercing action of the HEAT round.

    For Ataka and Shturm there are separate missile types for different roles so you need to carry a balance mix of missiles depending on what you are expecting to encounter.

    Large Soviet SAMs have huge warheads and the newer ones (after the 1970s) and their upgrades tasked with engaging targets from tiny cruise missiles at low altitude to ballistic missiles near space and aircraft and other targets in between use multiple fuses called smart fuses where at the last second before interception the nose sensor determines the actual location of the target and based on the target type will activate the specific fuse to direct the blast of the warhead in the direction of the target depending on the target, so unlike Patriot with a spherical blast, the later model S-300s directed their fragments to intercept a high speed missiles nose (ie warhead) rather than wasting fragments hitting its centre or rear that are no longer active. For manned aircraft it can be set to hit the front of the cockpit... like the old model BUK did... it makes them more effective and efficient.

    But what I can say, is that only the frontal area and leading edges of old aircraft may need to be converted. For low RCS frontal attack.

    And if you spend billions making all your aircraft fronts more stealthy how are you going to feel during defensive operations when you really don't know where the enemy is coming from and even in an attacking role enemy radars will be everywhere... When you are flying to one target, interceptors and SAMs in places on the way will take off to intercept you from the side and from the rear where you are not stealthy at all... all that money spent and that needs to be continuously spent to keep those planes stealthy was wasted... especially the internal weapons loads which will greatly reduce the performance of the aircraft while being stealthy... the F-111 had an internal bomb or weapon bay but 99% of the time it was fitted with a gun and ammo, or a fuel cell... because it was small and limited the performance of the aircraft if that was the only place it could carry weapons.

    You are better off spending a minimum to prevent excessively large RCS for your aircraft and just arm them properly with lots of AAMs and sensors and systems.

    Regarding cooled leading edges of  F35. I suspect that cooling of body parts will be controlled to that of surrounding or background temperature. So IR seekers will have difficulty still. I thought about evaporative cooling of missiles and UAV on approach to target.

    They would seriously struggle to get surface temperature the same as background temperatures... especially with that engine running... and that nose mounted radar might be a LPI AESA, but they generate lots of heat when they are being used too.

    I do not see why an aircraft can be low RCS, but missile can not be.

    Of course they can be, but for every aircraft you will be making hundreds of missiles... which are already expensive... making them vastly more expensive is pointless... they will be visible to IR and just optical sensors no matter what you do, and making them radar stealthy makes a million dollar missile into a 20 million dollar missile that is no more capable and might need special treatment too like air conditioned shelters and to be kept dry and ice free... or they wont be stealthy.

    Of course for ARH missiles it would be totally pointless once they start scanning looking for the target...

    Also a frangible coating only operates when missile skin gets very hot. Well away from aircraft. But I think actual test will provide answer. A shaped triangular or diamond shaped AA missile, will not need frangible coatings.

    If it is going to heat up then wont defensive IR sensors detect it anyway?

    Most self defence EW suites detect incoming threats based on IR sensors, not radar normally.

    Agree about needing limited number of very low RCS planes at higher costs for specific jobs. Such as SEAD . But also refuelling UAV Tankers now being designed. This was weak point in air war. The huge clumsy air Tankers.

    They are necessary for invasions, but most Russian aircraft already have excellent flight range anyway... plus there is the potential for self defence missiles to make them safer... you could use an enormous aircraft like Slon so it could carry enormous amounts of fuel it could offload with 5 or 6 hose reels to refuel larger numbers of aircraft at a time and with external weapons pylons with small self defence missiles... together with some rather potent laser and EM weapon stations that could obliterate the tiny seeker and mind of any missile you might consider directing at it.

    About point I made about Iran purchasing Russian jet engines. I would like a reply if possible. My idea is that sooner or later Iran will manufacture turbojet. And it will start selling planes and being a competitor. But if there is a joint venture, then the path to success is shorter for Iran. And for Russia it will mean sharing in profits of new more cost effective fighters / trainers. The Europeans shared the load. And rewards. Why not Iran / Russia or China?

    That Iranian trainer is about a 5 ton platform, which is about half the weight of the Yak-130 fully loaded.

    I personally think LIFT fighters are a stupid idea... on paper it makes sense to have commonality between aircraft and having a small light cheap aircraft for training that can also deliver real payloads for training and for real sounds ideal because light fighters should be simple and cheap and manouverable.

    Problem is that to be capable you need to start adding some things that make it not so cheap and not so light, and the light weight becomes an issue as the Air Force starts to demand more capability... the electronic self defence suite and radar alone will make it a very expensive aircraft, but if you cheap out and try to save money by not having them and your pilots will die cheaply against real enemies.

    For COIN type ops a light strike plane with cheap dumb weapons can be useful, but when push comes to shove I personally think taking a medium weight aircraft, and putting light weight lower performance equipment in that will give you your commonality and better base performance... ie MiG-29M2 as your cheap light fighter plus MiG-35s as your medium fighter and a few Su-35s or Su-57s for the hard jobs and top units.

    In fact you could modify it a bit... move the engines further apart and fill in the gap with an internal weapon bay and have further weapon locations on the outside of the engine bays so that much of the time you can have wings with no pylons to reduce RCS.... reduce its flight speed to mach 1.6 or so.
    nomadski
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    Post  nomadski on Fri Nov 22, 2019 4:15 pm


    They say this technology is real and practical. Can it be used on aircraft or tanks to make invisible?

    https://youtu.be/CFiPJjrmmtE

    GarryB
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    Post  GarryB on Sat Nov 23, 2019 2:58 am

    Just on that still frame without watching the video... I can't see the handles of those pliers... but I can see the piece of material he is holding up and can realise it might be blocking my view of something... if I saw that on a battlefield or flying through my airspace I would shoot it to see what it is hiding.

    Why would a civilian aircraft or vehicle use such technology?

    With the first battle damage or normal wear and tear cracks will it still work?

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