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    Avangard hypersonic glide vehicle (“object 4202”)

    Hole
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    Post  Hole on Thu Jan 03, 2019 9:21 pm

    The deeper it dives into the atmosphere the better the scramjet will work. There it can gain speed again, climb back into near space and so on.
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    Post  dino00 on Fri Jan 04, 2019 12:38 am

    Arrow wrote:At such altitude, HGV quickly loses speed. In the final part of the flight, maybe it's from 3M. HGV has no drive. Scramjet motors do not work at this height.
    A flight at 100 km requires a lot of energy.

    lol1 lol1 lol1 Borisov said That Avangard travel at mack 27 and picked up speed
    Nice try Razz Razz
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    Post  GarryB on Fri Jan 04, 2019 3:58 am


    not really, ir is much more expensive. Yet bringing very little in return. You need very same Avangard just with no nuclear warhead. You loose "place" on ICBM which is very expensive.
    While every Avangard takes already 2 orders od magnitude ABMs. Why to waste place on ICBMs?

    Makes you wonder why they carry decoys on normal ICBMs... replacing a real warhead with a fake one?

    The fake ones can be hollow and you can stack dozens together in the space normally needed for one real warhead...

    But lets not let facts get in the way...

    HGV quite quickly slows down probably.

    An unpowered glider like the space shuttle lands at subsonic speeds... Avangard is powered... that is what makes it special and it is also why the US hasn't got one too.

    With scramjet propulsion it could actually fly faster than any other ICBM... an ICBM flying faster than 11km/s will leave earth orbit unless it is turned constantly to keep it inside the atmosphere. A scramjet powered object has no speed limit...

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    Post  Teshub on Fri Jan 04, 2019 2:13 pm

    GarryB wrote:With scramjet propulsion it could actually fly faster than any other ICBM... an ICBM flying faster than 11km/s will leave earth orbit unless it is turned constantly to keep it inside the atmosphere. A scramjet powered object has no speed limit...
    Sorry Garry I may be misunderstanding you, but surely there are multiple restrictions to a scramjet powered object's velocity?

    First off would be exhaust velocity i.e. the actual top speed air molecules can be ejected from the engine. Secondly is orbital velocity else you inadvertently climb above the mesosphere (unless you wish to waste fuel). Thirdly is structural, as even rarefied atmosphere will act as a brick wall at sufficient speeds and you don't want your vehicle's lifting body to buckle. Fourthly would be thermal as increasing the shock wave increases plasma temperatures, whose radiant energy will overcome surface protection via ablation of material or convection to the superstructure beneath. There are probably others to do with turbulence and such, but I have little knowledge of those aspects.

    (Apologies if your statement was just an offhand comment, or that you intended a different imperative.)
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    Post  dino00 on Fri Jan 04, 2019 10:29 pm

    About the aparent doubt that Avangard will go to Sarmat Tass in march:

    “In the early 2000s, about 30 UR-100N UTTH liquid missiles were delivered from Ukraine for“ gas debts ”, after the collapse of the USSR, they were stored in warehouses in an unfilled state — that is, practically new, able to stand on duty for several decades. these missiles will become carriers of the first series of hypersonic planning warheads over the coming years, "the agency’s source said.

    He added that "with the adoption of the heavy RS-28 Sarmat missile, such units will be installed on it."

    12 Avangard for the less than 30 SS-19 the others for Sarmat.
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    Post  GunshipDemocracy on Fri Jan 04, 2019 11:58 pm

    Arrow wrote: The flight at 27M was probably in the initial phase. The question with what speed it ended. HGV quite quickly slows down probably.

    on what would you base your assumptions? unpowered flight of shuttle took half of equator to land. Here you have something with similar but with powered flight.
    Not sure why do you assume that atmosphere on this altitude breaks you so hard? above Karman line Shuttle can fly 25+ Ma with virtually no friction?

    Besides you of course know that total energy is kinetic + potential. So going down increases your kinetic so you can go up minus friction/adiabatic compression loses.

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    Post  GunshipDemocracy on Sat Jan 05, 2019 12:26 am

    GarryB wrote:Makes you wonder why they carry decoys on normal ICBMs... replacing a real warhead with a fake one?
    The fake ones can be hollow and you can stack dozens together in the space normally needed for one real warhead...

    But lets not let facts get in the way...

    So you talk about MIRVs with ballistic warheads? so how many ABMs were needed to take down all 6 MIRVs before (including decoys) ? MIRV is form interdependently targetable, they dont change course nor trajectory. they fly on ballistic trajectory. If you have many ICBMs then it makes sense.

    But now amount of ABMs needed to intercept 1 literally ONE Avangard. It is close to 20x of all interceptors installed by now.

    Do i get you correctly that instead of 12 Avangards till 2027 Russians should use only 3-4 real warheads? so to waste 9 ICBMs achieving not real damage?  In the future build Samrat with 1-2 Avangards and rest places shoot empty shells over south pole?

    Frankly speaking I see no advantages such approach.




    HGV quite quickly slows down probably.


    With scramjet propulsion it could actually fly faster than any other ICBM... . A scramjet powered object has no speed limit...

    [/quote]

    AFAIK max scramjet speed is like 25 Ma. So no it has to fly withing atmosphere but not oo low (pressure, temp + energy dissipation) or too high (scramjets work up to ~75km, for rocket thursters you need oxidizer. ) . There are many considerations but Teshub explained nicely physics before and in competent way respekt respekt respekt
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    Post  Teshub on Sat Jan 05, 2019 1:01 am

    GunshipDemocracy wrote:AFAIK max scramjet speed is like 25 Ma. So no it has to fly withing atmosphere but not oo low (pressure, temp + energy dissipation) or too high (scramjets work up to ~75km, for rocket thursters you need oxidizer. ) . There are many considerations but Teshub explained nicely physics before and in competent way respekt respekt respekt
    I am not as grounded in mil-tech as some of you guys, but I try my best.
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    Post  GunshipDemocracy on Sat Jan 05, 2019 1:42 am

    Teshub wrote:I am not as grounded in mil-tech as some of you guys, but I try my best.

    no need to underestimate your contribution. Together we all have better "hive knowledge" after each constructive input lol1 lol1 lol1
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    Post  GarryB on Sat Jan 05, 2019 5:31 am

    Sorry Garry I may be misunderstanding you, but surely there are multiple restrictions to a scramjet powered object's velocity?

    What I mean to say is that different engine types have different "efficient or effective" speed ranges.

    A propeller driven aircraft... whether piston engine driven or turboprop is strictly a subsonic engine no matter what technology you use.

    A turbofan with a high bypass ratio like on commercial jets and large transport aircraft are subsonic too.

    A turbojet engine is limited to a speed of about mach 2.8... mostly because of rotational speed issues with the shaft mounted blades, and also partly because the air flowing through it needs to be slowed down to subsonic speed in the hot section where the fuel is burned.

    A ramjet engine is good for speed of mach 4-6 depending upon the type, and its main limitation is the fact that the fuel is burned in an area of the engine at subsonic speeds.

    A scramjet burns fuel at supersonic speeds so you can compress the air but you don't need to slow it down to burn the fuel.

    In a ramjet at mach 5 the air is flowing into the engine at mach 5 so the engine intake needs to narrow down and reduce the volume of air entering the intake to a rather small amount, the volume is then artificially increased by compressing it and slowing it down to subsonic speeds where fuel is added and blasted out the rear of the engine at high speed to generate thrust.

    Now imagine a scramjet at the same speed of mach 5 but it can burn its fuel at supersonic speed so it can have its intake open much wider letting a lot more air flow through the engine... air compression would not be a problem, and adding fuel and burning it means the exhaust speed can be much much higher because it does not need to be slowed down to subsonic speed for ignition...

    Hense a scramjet can offer enormous amounts of thrust at very very high flight speeds... whereas a ramjet offers less and less the faster it goes.

    In theory there is no limit to the top speed of a scramjet... in practise the limit is of course heat.

    Even orbital speed is not a limit for a scramjet... in theory you could have an aircraft with turbojet engines that are retractable up into the structure of the aircraft but the air intakes and exhaust tubes remain where they are under the belly of the aircraft. Turbojets power the aircraft on the runway and up into the air, but once flying... even at subsonic speed first one and then the other could retract into the body of the aircraft with the airflow through the intake and exhaust becoming a ramjet... or more accurately a scramjet... that lights up and accelerates the aircraft from subsonic speeds up to and beyond orbital speeds... its control surfaces pushing the nose down keeping the aircraft inside the atmosphere until escape velocity is achieved and then point the nose up and leave the atmosphere... obviously outside the atmosphere the scramjets would not work any more as scramjets but they have fuel injected into the airflow to act as scramjets, so close the now redundant intakes and pump pure oxygen, or a safer mix of oxygen and nitrogen and burn the fuel in that as a rocket to manouver in space if you want to... or to exit orbit... small compressed air jets around the aircraft could flip it over in space so its rear is faced forward and the engines run in rocket mode to slow down to reenter the atmosphere... and use its wings to glide down like a space shuttle... but with scramjet or if you want turbojet to fly like a normal aircraft.

    First off would be exhaust velocity i.e. the actual top speed air molecules can be ejected from the engine.

    The definition of thrust is that it goes out faster and hotter than it went in... if the air going into a scramjet is going at mach 27, then I don't see why accelerating it 1/27th of its speed to mach 28 would be all that difficult... which should be enough to overcome drag and maintain speed.

    Secondly is orbital velocity else you inadvertently climb above the mesosphere (unless you wish to waste fuel).

    Indeed it is, but so? Imagine an asteroid from deep space that is moving at 20km per second... it could penetrate our atmosphere a glancing blow... to within 1km of the surface... but because of the angle head back out into space without impacting the ground.

    A controlled vehicle like this glider can manouver, which means no matter how fast it goes it can turn and remain inside the atmosphere... if it is scramjet powered then it needs an atmosphere for its jet motor to operate within...

    Thirdly is structural, as even rarefied atmosphere will act as a brick wall at sufficient speeds and you don't want your vehicle's lifting body to buckle.

    You might be confusing air with water... going from a vacuum you can come in too steep... in which case you are moving too fast and will burn up because of the high friction heat generated at that speed, or you can come in too shallow and skip off the atmosphere like a stone on a pond, or you can get the angle just right and enter at a safe reentry speed.


    This glider is designed to operate at enormous speeds so one assumes its thermal protection is significant so the only real risk would be exiting the atmosphere and then trying to reenter at an angle too shallow and skipping... but why in the vacuum your scramjet engine will not be generating thrust so you will just be coasting so when you hit again you will lose speed on each skip... so the next skip will be a steeper angle until it is too steep to skip and you will plunge back into the atmosphere...

    Fourthly would be thermal as increasing the shock wave increases plasma temperatures, whose radiant energy will overcome surface protection via ablation of material or convection to the superstructure beneath.

    This is really the only valid limit on the top speed of a scramjet powered aircraft... Heat.

    Inside the engine and the outer surface of the craft.

    There are probably others to do with turbulence and such, but I have little knowledge of those aspects.

    Not much in the way of weather at very high altitudes, certainly nothing at the 40-100km altitudes these gliders likely will be operating in...

    (Apologies if your statement was just an offhand comment, or that you intended a different imperative.)

    I didn't mean you could exceed the speed of light with a scramjet motor... it is a pretty much unknown area, but the only limits seems to be temperature.... both inside the engine and outside the aircraft. You could assist with both by pumping slush hydrogen through the skins... of the surface of the aircraft and the hot parts of the engine... the now heated slush hydrogen could then be used as preheated fuel in the scramjet engine...

    12 Avangard for the less than 30 SS-19 the others for Sarmat.

    The SS-19 is an excellent missile and they were also using them for launching satellites... there was talk that by 2022 they would be able to replace all Ukrop parts and make their own in the interests of using them for satellite launches too.

    So you talk about MIRVs with ballistic warheads? so how many ABMs were needed to take down all 6 MIRVs before (including decoys) ? MIRV is form interdependently targetable, they dont change course nor trajectory. they fly on ballistic trajectory. If you have many ICBMs then it makes sense.

    Decoys are stacked... with 50 missiles you could have 10 warheads each... 500 warheads, or with 6 warheads each plus decoys you could have 300 warheads, and 1000 decoys.

    But now amount of ABMs needed to intercept 1 literally ONE Avangard. It is close to 20x of all interceptors installed by now.

    Indeed, that is their purpose...

    Do i get you correctly that instead of 12 Avangards till 2027 Russians should use only 3-4 real warheads? so to waste 9 ICBMs achieving not real damage? In the future build Samrat with 1-2 Avangards and rest places shoot empty shells over south pole?

    Decoys are produced separately... and jammers as well.

    What I am suggesting is that if you can fit 5 Avangard warheads in one small missile, and on a bigger missile you could have two stacks of avangards for 10 gliders, if you have 12 avangard gliders then take on small ICBM and fit three avangard gliders, and in the space the other two gliders would sit fit 8-10 decoys. In a big ICBM then instead of two stacks of 5 gliders have two stacks of three and 16-20 decoys in the remaining spaces.

    It means the 12 gliders you are going to make will need four small ICBMs or two large ICBMs, with 32-40 decoys either way.... so the US air defence network need to deal with 44-52 targets that will all look from the front on like Avangard gliders and will manouver like avangard gliders, but only 12 will cost what the gliders cost and 44-52 of them will be rather cheaper because they have no guidance and are just randomly manouvering like the real ones...

    They might have relatively cheap inertial guidance...

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    Post  Teshub on Sat Jan 05, 2019 5:55 pm

    GarryB wrote:Now imagine a scramjet at the same speed of mach 5 but it can burn its fuel at supersonic speed so it can have its intake open much wider letting a lot more air flow through the engine... air compression would not be a problem, and adding fuel and burning it means the exhaust speed can be much much higher because it does not need to be slowed down to subsonic speed for ignition...
    Agreed.

    In theory there is no limit to the top speed of a scramjet... in practise the limit is of course heat.
    Here I disagree (other than destructive vehicle heating being the current main limiter). There are theoretical maximums to scramjet velocity based upon the limits of heat release/expansion velocity of the fuel per unit of time. This in itself is variable dependant on air density and velocity, but it eventually does top out.

    Even orbital speed is not a limit for a scramjet...
    Umm, as far as I am aware, there are no theoretical scramjet designs which can currently achieve escape velocity. On paper its not possible. Even Skylon using its conceptual hybrid SABRE engines, requires last stage use as pure rockets to achieve orbit.

    The definition of thrust is that it goes out faster and hotter than it went in... if the air going into a scramjet is going at mach 27, then I don't see why accelerating it 1/27th of its speed to mach 28 would be all that difficult... which should be enough to overcome drag and maintain speed.
    I think you underestimate the difficulties. We can barely make a scramjet capable of brief burns at Mach 5 last for a minute. Even if a Mach 27 scramjet was theoretically possible, it would have to be made from solid unobtanium to handle the thermal loads.

    Thirdly is structural, as even rarefied atmosphere will act as a brick wall at sufficient speeds and you don't want your vehicle's lifting body to buckle.
    You might be confusing air with water... going from a vacuum you can come in too steep... in which case you are moving too fast and will burn up because of the high friction heat generated at that speed, or you can come in too shallow and skip off the atmosphere like a stone on a pond, or you can get the angle just right and enter at a safe reentry speed.
    From an aerodynamic/astroengineering perspective it is vital to keep the superstructure mass to the lowest possible value. Excess structure means excess mass to accelerate. Therefore it places an engineering limit on velocity. This is why orbital rockets throttle back when approaching MaxQ after launch, otherwise they can buckle.

    Of course a hypervelocity vehicle has a different geometry, which naturally makes it stronger than a long thin tube. Even so, a launching orbital rocket isn't travelling that fast at the altitudes we are talking about. The Falcon 9 hits 50km at a little under Mach 5 and departs 70km at a little over Mach 6. You are suggesting vehicles which could travel extended periods at Mach 27. Even at rarefied altitudes it will experience huge aerodynamic stress. ICBM warheads only have to survive it for a few seconds, and are decelerating at that.

    By the way, I think you mean heat generation from ram pressure.

    There are probably others to do with turbulence and such, but I have little knowledge of those aspects.
    Not much in the way of weather at very high altitudes, certainly nothing at the 40-100km altitudes these gliders likely will be operating in...
    Smile I didn't mean weather turbulence. I was talking about the fluid dynamics of air flow through the scramjet and over the lifting body, since the velocity range is so wide you cannot design the engine and airframe to be optimal over all speeds/atmospheric pressures.

    I didn't mean you could exceed the speed of light with a scramjet motor... it is a pretty much unknown area, but the only limits seems to be temperature.... both inside the engine and outside the aircraft. You could assist with both by pumping slush hydrogen through the skins... of the surface of the aircraft and the hot parts of the engine... the now heated slush hydrogen could then be used as preheated fuel in the scramjet engine...
    Oh don't worry, I didn't think you meant that. I was just a little confused as to your assertion which contradicts my physics knowledge. There is a lot more depth to this subject.
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    Post  GarryB on Sun Jan 06, 2019 3:34 am

    Here I disagree (other than destructive vehicle heating being the current main limiter). There are theoretical maximums to scramjet velocity based upon the limits of heat release/expansion velocity of the fuel per unit of time. This in itself is variable dependant on air density and velocity, but it eventually does top out.

    The U-2 spyplane flies a tightwire act of balancing altitude and flight speed, just on the border of mach one that it cannot go beyond because of its shape.

    It would be no surprise that an object already moving at over 7km/s as it enters the atmosphere might have some issues starting and running a scramjet engine... especially with the vagaries of the shape of the atmosphere and its chemical make up... the o2 concentration being an issue of course...

    Umm, as far as I am aware, there are no theoretical scramjet designs which can currently achieve escape velocity. On paper its not possible. Even Skylon using its conceptual hybrid SABRE engines, requires last stage use as pure rockets to achieve orbit.

    And 300 years ago there were no jet designs that could get a heavier than air craft airborne on its own power and on paper it was not possible then.

    Perhaps Skylon is waiting for a better scramjet to be designed... we are not talking about an aircraft that takes off from the ground and flys into space as my example described... we are launching this glider to enormous speeds on an ICBM so it really only has to maintain speed and accelerate slightly to achieve what they are claiming...

    I think you underestimate the difficulties. We can barely make a scramjet capable of brief burns at Mach 5 last for a minute. Even if a Mach 27 scramjet was theoretically possible, it would have to be made from solid unobtanium to handle the thermal loads.

    Tests in the 1990s with SA-5 missiles had a scramjet attached to its nose operating for one and a half minutes.

    They have test fusion reactors operating for short periods at over 1 million degrees C, with magnetic containment keeping the high temperature plasma separated from any surfaces it would melt...

    From an aerodynamic/astroengineering perspective it is vital to keep the superstructure mass to the lowest possible value. Excess structure means excess mass to accelerate.

    So making it out of string would keep its mass to a very low value... do you think that would really help?

    Excess structural strength is needed because these gliders have to manouver as well as go really fast... the extra weight would help them deal better with the drag the atmosphere would transfer to the glider... once in motion a heavier object maintains speed better than a lighter one of the same given shape and size.

    Shape and size are limited by the space for the glider inside the launch rocket, so a heavier one or a lighter one makes a difference only in the sense of sectional density... take a 50g balloon and fill it with 450 g of air and you have a 500g mass. Take another 50g balloon and fill it with 2 litres of water and you have 2050g water balloon... now throw them both through the air... the heavier water balloon will take more energy to accelerate but it will also retain speed much better than the air filled balloon.

    Of course balloons are fragile so a glider would be made with a heavier structure... more like a hot water bottle rather than a balloon so that it is less likely to burst, whether filled with air or water.

    The Falcon 9 hits 50km at a little under Mach 5 and departs 70km at a little over Mach 6. You are suggesting vehicles which could travel extended periods at Mach 27. Even at rarefied altitudes it will experience huge aerodynamic stress. ICBM warheads only have to survive it for a few seconds, and are decelerating at that.

    You are looking at the wrong end of the trip... as it comes down back in to the atmosphere is where it will be starting its scramjet motor and will change from a ballistic path to a powered flight path...

    Smile I didn't mean weather turbulence. I was talking about the fluid dynamics of air flow through the scramjet and over the lifting body, since the velocity range is so wide you cannot design the engine and airframe to be optimal over all speeds/atmospheric pressures.

    It is a glider... like the Space shuttle... that flew at speeds of Mach 25 down to landing speed... except this glider has propulsion to maintain high speed for longer but it wont need to operate for hours at that speed... most satellites move at 7-8km/s and do complete orbits of the planet in 90 minutes... these gliders might be flying 6,000km... at mach 27 that means say the speed of sound is a nice round 300m/s, then mach 27 is about 8km/s, so 6,000km at 8km/s is about 12 and a half minutes of flight.

    There could be all sorts of measures to reduce heat issues... ablative aerospikes, ablative ceramics, pumped slush hydrogen fuel...

    Oh don't worry, I didn't think you meant that. I was just a little confused as to your assertion which contradicts my physics knowledge. There is a lot more depth to this subject.

    Hey... I am the ideas man... let the nerds work out the details... Twisted Evil

    I remember reading books from the 1950s where ramjets were all the rage and by the 1970s fighter planes would all be flying at mach 3-5 and by now they would be flying much much faster.

    Of course reality set in... often flying really fast is like firing a lot of bullets in a machine gun with a very high rate of fire... there are overheating problems and you run out of fuel or bullets real fast.

    Sometimes a high rate of fire or high speed is useful... ie MiG-31 or Kashtan CIWS, but most of the time a lower speed makes it simpler and cheaper... and it still gets the job done.
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    Post  GunshipDemocracy on Sun Jan 06, 2019 2:08 pm

    GarryB wrote:A scramjet burns fuel at supersonic speeds so you can compress the air but you don't need to slow it down to burn the fuel.
    +++
    Hense a scramjet can offer enormous amounts of thrust at very very high flight speeds... whereas a ramjet offers less and less the faster it goes.


    not true, look at efficiency to SCramjet vs  speed only in 10Ma range it trops, it also needs high drag to get compression.


    from nasaflight (non NASA tho) forum:

    from nasa forum wrote:SCramjets bad, SABRE good?
    -----------------------------------------------------------------------------------------------
    Scramjets bad, SABRE meh, ramrockets good. Ram rockets don't have combustion efficiency issues.

    Quote from: sanman on 05/27/2016 01:19 am
    Hmm, okay, so it comes down to the compression ratio under supersonic combustion not being as good as in rockets. Does the scramjet compression ratio improve as you go faster?

    -------------------------------------------------------------------------------
    Yes, but at a HUGE cost. That higher compression ratio comes simultaneous with both higher compression heating AND higher drag. Drag is the killer. The thrust of a rocket depends on the momentum of the exhaust alone; the thrust of a scramjet depends on the momentum of the exhaust minus the momentum of the intake airstream. That's why the thrust to weight ratio of scramjets sucks so bad; no only is the engine very heavy, but the vehicle's forward velocity directly robs net thrust and thus acceleration.

    And all the while, peak heating goes up with the cube of velocity while compression ratio only goes up with the square of velocity. This causes combustion efficiency to drop, not increase.





    https://forum.nasaspaceflight.com/index.php?topic=40380.0
    http://www.thespacereview.com/article/1092/1
    https://www.boeing.com/news/frontiers/archive/2002/september/i_tt.html



    GB wrote:In theory there is no limit to the top speed of a scramjet... in practise the limit is of course heat.
    +++
    Even orbital speed is not a limit for a scramjet...

    From nasa forum wrote:The fastest scramjet has achieved a velocity of ~3.1 km/s as compared to orbital velocity being ~7.8 m/s, so that's about 40% of the required velocity.
    What is currently the limiting factor on the speed which scramjets can attain?

    ----------------------------------
    The limiting factor is physics. When the air is entering your intake faster than you can push it out the back, you can no longer thrust. The maximum speed at which you can push it out the back depends on your fuel and is around 4.5 km/s for liquid hydrogen, but since your intake is not pure oxygen you're never going to get that high. And even if you could (here's the nasty part) your maximum net thrust at 4 km/s is only 20% of your net thrust at 2 km/s. The faster you go, the less net thrust you get.

    ok I didnt calculate it but ~12Ma on an atmospheric oxidizer or 15Ma pure oxugen is top limit.  What is surprisingly close to GUR 12-14Ma (II stage) speed.




    GB wrote:Secondly is orbital velocity else you inadvertently climb above the mesosphere (unless you wish to waste fuel).

    your energy is sum potential + kinetic - looses (drag/compression)



    GB wrote:A controlled vehicle like this glider can manouver, which means no matter how fast it goes it can turn and remain inside the atmosphere... if it is scramjet powered then it needs an atmosphere for its jet motor to operate within..
    .

    looks like a rocket one then what is more efficient at those speeds for sure



    GB wrote:
    Teshub wrote:Thirdly is structural, as even rarefied atmosphere will act as a brick wall at sufficient speeds and you don't want your vehicle's lifting body to buckle.

    You might be confusing air with water... going from a vacuum you can come in too steep... in which case you are moving too fast and will burn up because of the high friction heat generated at that speed, or you can come in too shallow and skip off the atmosphere like a stone on a pond, or you can get the angle just right and enter at a safe reentry speed.


    most of temp is Ek converting to heat due to adiabatic compression, friction is tiny part of this




    GB wrote:
    There are probably others to do with turbulence and such, but I have little knowledge of those aspects.

    Not much in the way of weather at very high altitudes, certainly nothing at the 40-100km altitudes these gliders likely will be operating in...

    I'm betting on closer to Karman line. 40km atmosphere is so dense that with 27Ma you'd cook/destroy device



    GB wrote:
    So you talk about MIRVs with ballistic warheads? so how many ABMs were needed to take down all 6 MIRVs before (including decoys) ? MIRV is form interdependently targetable, they dont change course nor trajectory. they fly on ballistic trajectory. If you have many ICBMs then it makes sense.

    Decoys are stacked... with 50 missiles you could have 10 warheads each... 500 warheads, or with 6 warheads each plus decoys you could have 300 warheads, and 1000 decoys.


    if you can build balloons and chaffs which  can maneuver with hypersonic speeds in atmosphere than yes, you're right/ Otherwise this is good only on orbital part of flight and absence fo optical intel satellites on US side. So no you waste place of your warheads.


    GB wrote:
    Do i get you correctly that instead of 12 Avangards till 2027 Russians should use only 3-4 real warheads? so to waste 9 ICBMs achieving not real damage?  In the future build Samrat with 1-2 Avangards and rest places shoot empty shells over south pole?

    Decoys are produced separately... and jammers as well.

    with better (and better algorithms) sensors and computational power discrimination of decoys on ballistic trajectories will become very capable, you cannot build hypersonic gliding balloon. Then not really you can put DAT and DAT into ICBM Im afraid.  







    GB wrote: It means the 12 gliders you are going to make will need four small ICBMs or two large ICBMs, with  32-40 decoys either way.... so the US air defence network need to deal with 44-52 targets that will all look from the front on like Avangard gliders and will manouver like avangard gliders, but only 12 will cost what the gliders cost and 44-52 of them will be rather cheaper because they have no guidance and are just randomly maneuvering like the real ones...

    They might have relatively cheap inertial guidance...


    it there is something gliding in atmosphere, has same mass/speed and spectrum footprint is it niether cheap nor small.  I cannot see how it can be a balloon and not full sized mockup perhaps costing fraction of price but taking Avangard place.



    This is my point in such case building mockups taking place of Avagards make no sense
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    Post  Russophile on Mon Jan 07, 2019 4:50 am

    Ladies & Gentlemen,

    Russia can do it.  It has the technology.

    https://www.youtube.com/watch?v=QKIhB8zoUGQ russia
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    Post  miketheterrible on Mon Jan 07, 2019 7:28 am

    It's all real and good. Issue now is how classified it is. We know it's real but would love to see some photos but oh well. I know the liberals of Russia are having a field day saying how fake Avangard is but of course, it's due to lack of evidence.

    Even though their Masters in the US admit it is real
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    Post  GarryB on Mon Jan 07, 2019 9:29 am

    GB wrote:
    Secondly is orbital velocity else you inadvertently climb above the mesosphere (unless you wish to waste fuel).

    I never said that.

    if you can build balloons and chaffs which can maneuver with hypersonic speeds in atmosphere than yes, you're right/ Otherwise this is good only on orbital part of flight and absence fo optical intel satellites on US side. So no you waste place of your warheads.

    If they were balloons you could hardly stack them.

    Think of orange road cones... when stacked you can fit a lot in a fixed space... but unstack them and stand them up and from the top they look the same as any solid cylinder shape...

    Once they enter the atmosphere and are powered they don't need decoys any more.

    with better (and better algorithms) sensors and computational power discrimination of decoys on ballistic trajectories will become very capable, you cannot build hypersonic gliding balloon. Then not really you can put DAT and DAT into ICBM Im afraid.

    Hahahaha... then what you do is modify your real warheads to act like the decoys and a few of the decoys to act like the real warheads... there will only be one test... the US wont get a chance to learn from their mistakes...
    ok I didnt calculate it but ~12Ma on an atmospheric oxidizer or 15Ma pure oxugen is top limit. What is surprisingly close to GUR 12-14Ma (II stage) speed.

    So these silly Russians are lying when they claim flight speeds of Mach 27 because some dick on the internet has numbers to prove the top limit is mach 14...
    Interesting...

    This is my point in such case building mockups taking place of Avagards make no sense

    The arsenal of Russia will not consist only of Avangard warheads... there will be loads of other types... and many more actual decoys and jammers.

    You seem to think that using decoys and dummys means less avangard warheads will be made...

    I know the liberals of Russia are having a field day

    Those bastards can enjoy themselves as much as they like...
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    Post  Teshub on Mon Jan 07, 2019 10:37 am

    GunshipDemocracy wrote:
    GB wrote:A controlled vehicle like this glider can manouver, which means no matter how fast it goes it can turn and remain inside the atmosphere... if it is scramjet powered then it needs an atmosphere for its jet motor to operate within..
    looks like a rocket one then what is more efficient at those speeds for sure
    I agree. At such low fuel efficiencies and superfluous engine mass, after already being propelled up to Mach 27 using an ICBM, it makes more sense that Avangard would use onboard rocket engines rather than a scramjet. Better energy density for the mission profile. Less risk of engine (re)ignition failure too if it continues to skip.
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    Post  Teshub on Mon Jan 07, 2019 10:39 am

    By the way, anybody else read this yet? It has a few little gems of history hidden in it.

    http://mragheb.com/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Nuclear%20Ramjet%20and%20Scramjet%20Propulsion.pdf
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    Post  GunshipDemocracy on Wed Jan 09, 2019 1:46 am

    Teshub wrote:
    I agree. At such low fuel efficiencies and superfluous engine mass, after already being propelled up to Mach 27 using an ICBM, it makes more sense that Avangard would use onboard rocket engines rather than a scramjet. Better energy density for the mission profile. Less risk of engine (re)ignition failure too if it continues to skip.

    indeed ths makes sense. Avangard flying with 27 Ma around Karman unlikely to be decelerated fast,  and rocket thrusters are added to correct height or turns not really to provide continuous propulsion.



    Teshub wrote:By the way, anybody else read this yet? It has a few little gems of history hidden in it.

    this you should post on Burevestnik thread (nuclear cruise missile), thanks for sharing BTW thumbsup thumbsup thumbsup
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    Post  GunshipDemocracy on Wed Jan 09, 2019 2:22 am

    GarryB wrote:Think of orange road cones... when stacked you can fit a lot in a fixed space... but unstack them and stand them up and from the top they look the same as any solid cylinder shape...

    yet their heating due to solar light and cooling in space can be detected. For heavy objects is different then for lighter one.



    GB wrote:
    with better (and better algorithms) sensors and computational power discrimination of decoys on ballistic trajectories will become very capable, you cannot build hypersonic gliding balloon. Then not really you can put DAT and DAT into ICBM Im afraid.
    Hahahaha... then what you do is modify your real warheads to act like the decoys and a few of the decoys to act like the real warheads... there will only be one test... the US wont get a chance to learn from their mistakes...

    if you modify real warheads as decoys then it is exactly same situation I've talked about 1 decoy +  = 1 Avagard -.  Great you agreed  thumbsup  thumbsup  thumbsup



    GB wrote:
    ok I didnt calculate it but ~12Ma on an atmospheric oxidizer or 15Ma pure oxugen is top limit.  What is surprisingly close to GUR 12-14Ma (II stage) speed.

    So these silly Russians are lying when they claim flight speeds of Mach 27 because some dick on the internet has numbers to prove the top limit is mach 14...
    Interesting...

    Russians never said anything about scram jet used there. I've never hear official info about any active propulsion either.  The only thing in TV Rossiy 1 was : designed to Ma 20 accelerated to Ma=27.  Nobody said it is about constant speed and not max velocity reached because fo ICBM energy. Nobody said 27Ma was constant in atmosphere either.

    There is limit set by laws of physics, not sure what is your knowledge of fluid dynamics but simply with airflow at some speed  you wont be able to inject and burn fuel.  Not to mention that with increasing temperature of inlet air  you need to dump more and more fuel to get decent expansion.

    Or thermal choking. Im poor with fluids dynamics but if you are good be my guest and tell a bit more about it.

    after wiki (referring to research paper) :
    Second, the heating of the gas by combustion causes the speed of sound in the gas to increase (and the Mach number to decrease) even though the gas is still travelling at the same speed. Forcing the speed of air flow in the combustion chamber under Mach 1 in this way is called “thermal choking”.



    BTW talking about dicks in internet I am a nice guy but If I were not the one I'd say that technically you are also a dick form net  lol1  lol1  lol1





    GB wrote:
    This is my point in such case building mockups taking place of Avagards make no sense

    The arsenal of Russia will not consist only of Avangard warheads... there will be loads of other types... and many more actual decoys and jammers.

    only Avangard locations are will known to us. So to US(A) will be known as well .




    GB wrote: You seem to think that using decoys and dummys means less avangard warheads will be made...

    in case of Avangard? yes I do.
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    Post  Arrow on Wed Jan 16, 2019 10:47 am

    About Avangard.

    https://www.novayagazeta.ru/articles/2019/01/14/79174-pentagon-v-vostorge?utm_referrer=https%3A%2F%2Fzen.yandex.com%2F%3Ffrom%3Dspecial&fbclid=IwAR1y9SKo10uSTtST2MSxGeFcWXiG_hN6AuyERwZPjXVMhNEqydNgObrr-Sk

    So standard MIRV is much better and harder to intercept. You can use more MIRV in ICBM. UR 100NUTTH carry only one Awangard.
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    Post  dino00 on Wed Jan 16, 2019 11:42 am

    Very Happy Very Happy The expert say is slower than mirv Very Happy
    Its easier to intercept, but later says the Americans cant intercept them Laughing
    Doesnt talk about how is easy to know the trajectory of mirv vs Avangard Very Happy
    Lies saying no one besides Russia will put a glider on top an ICBM.
    The expert doesnt know what the hell is talking about.
    Avangard M27 picked up speed
    More wishfull thinking please
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    Post  Arrow on Wed Jan 16, 2019 11:52 am

    Avangarde flies from 27M only at the beginning. Then it loses speed very quickly. It is slower than MIRV, it is much bigger and more expensive. MIRV have additional decoys.
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    Post  dino00 on Wed Jan 16, 2019 12:22 pm

    Arrow wrote:Avangarde flies from 27M only at the beginning. Then it loses speed very quickly. It is slower than MIRV, it is much bigger and more expensive. MIRV have additional decoys.

    Avangarde flies from 27M only at the beginning

    Lie number 1: Borisov Said it picked up speed

    Then it loses speed very quickly

    Lie number 2: how do you know? Sources for This lie? The Americans know the exact speed and range of the missile Russia test since some years ago(telemetry boom tass sources years ago) and they say they cant intercept.

    It is slower than MIRV

    Lie number 3: the test range of the first version of Avangard proved That the time from launch to hit is obviously reduced. What will be the point of prompt global strilke otherwise?

    MIRV have additional decoys.

    Well more decoys less Mirv.

    The purpose of Avangard is to Americans know That some missiles will always hit them, not to change every warhead with an unstoppable M27 picked up speed, manouvrable vehicle
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    Post  GunshipDemocracy on Thu Jan 17, 2019 3:44 am

    Arrow wrote:About Avangard.

    so if you listen to every moron blogger as an expert? dat dude is some radio engineer no military nor rocket specialist. Then you got certain level of knowledge. s they say in data science: garbage in garbage out

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