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Log inFeel sorry for Musk , even if he sells starlink to Ukrs ? The design did not look right . More like stuffed sausage . He would have been better starting small ( er ) . The probability of fail goes higher with increasing number of Engines , even if stress per Engine is less . I could tell problem started at beginning . Lift- off was slow or delayed that allowed exhausts gas blow back against Engines . There was damage to Engine exhaust casing , visible by escaping hot gases . There is also symmetry to Engine fail , indicating problem perhaps with fuel pump , feeding opposite engines . Perhaps auto shut - down in case of fire . Then Rocket could not manoeuvre . Space too big for single company , or single nation or even single planet !
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Russian Space Program: News & Discussion #4
nomadski- Posts : 3073
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Feel sorry for Musk , even if he sells starlink to Ukrs ? The design did not look right . More like stuffed sausage . He would have been better starting small ( er ) . The probability of fail goes higher with increasing number of Engines , even if stress per Engine is less . I could tell problem started at beginning . Lift- off was slow or delayed that allowed exhausts gas blow back against Engines . There was damage to Engine exhaust casing , visible by escaping hot gases . There is also symmetry to Engine fail , indicating problem perhaps with fuel pump , feeding opposite engines . Perhaps auto shut - down in case of fire . Then Rocket could not manoeuvre . Space too big for single company , or single nation or even single planet !
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kvs- Posts : 15861
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The N-1 engines were world class. A batch of them that was supposed to be scrapped because the Soviet regime was too butthurt to think rationally was saved and found valuable use later. The N-1 was a plumber's nightmare that did not have proper control for resonances which shook it apart. Musk's masterpiece has zero excuse. SpaceX has vast computer and accumulated design resources to simulate their rockets at all stages of operation. Sure, garbage in equals garbage out, but do not dismiss engineering simulations as nonsense. They solve problems such as afflicted the N-1.
The launch video appears to show catastrophic failures of some of the engines. Either the quality assurance for the engines is crap or there is a design flaw
with the plumbing. So, no progress after over 50 years.
The launch video appears to show catastrophic failures of some of the engines. Either the quality assurance for the engines is crap or there is a design flaw
with the plumbing. So, no progress after over 50 years.
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Big_Gazza- Posts : 4908
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There is apparently catatrophic damage to the concrete apron beneath the launch pedestal as SpaceX elected not to build flame diverters/trenches or install water spray systems. As a consequence the shock waves from the engines tore the apron into pieces and excavated a deep hole in the earth, with the excavated earth blasted in all directions as a debris cloud (thats not just exhaust fume billowing out from the pad 
). There was apparently some damage to the tank farm from flying concrete debris.
Look at the vast flame trench system the Soviets built for N-1 by comparison to the measly SpaceX launch table. Thats how a real pad is designed and built.
Pundits claim this omission was a deliberate decision as the Starshit is "intended" to take off from the moon and Mars ( ) so it needs to be able take off without a well prepared pad, but thats total nonsense. Even if the moon/mars propaganda were truthful (which it isn't) the Starshit vehicle only has 3 engines, not 32 like BFR, so any hypothetical liftoff from either will never involve similar liftoff energies. In reality, i think SpaceX was just being cheapskates and wanted to spend as little as possible on launchpad infrastructure.
BTW good point from KVS. Korolev/Mishin didn't have sophisticated computer-based analytical tools to investigate complex fluid dynamics and structural/piping vibrational modes, so they had little choice but to fly missions to identify problems post-mortem. SpaceX has zero such excuse, and i find it astonishing that they didn't anticipate the damaging effects of reflected shock waves on liftoff.
). There was apparently some damage to the tank farm from flying concrete debris. 
Look at the vast flame trench system the Soviets built for N-1 by comparison to the measly SpaceX launch table. Thats how a real pad is designed and built.
Pundits claim this omission was a deliberate decision as the Starshit is "intended" to take off from the moon and Mars (
) so it needs to be able take off without a well prepared pad, but thats total nonsense. Even if the moon/mars propaganda were truthful (which it isn't) the Starshit vehicle only has 3 engines, not 32 like BFR, so any hypothetical liftoff from either will never involve similar liftoff energies. In reality, i think SpaceX was just being cheapskates and wanted to spend as little as possible on launchpad infrastructure.BTW good point from KVS. Korolev/Mishin didn't have sophisticated computer-based analytical tools to investigate complex fluid dynamics and structural/piping vibrational modes, so they had little choice but to fly missions to identify problems post-mortem. SpaceX has zero such excuse, and i find it astonishing that they didn't anticipate the damaging effects of reflected shock waves on liftoff.
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owais.usmani- Posts : 1828
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Arkanghelsk wrote:Starship is a stupid concept
I am actually waiting for SpaceX to put people on that thing. That is when the real fun starts!
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jon_deluxe- Posts : 15
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It is surreal to see the press and large swathes of the internet lose their minds over a failed launch, celebrating over what was basically a failure like the ones that plagued the N1 program half a century ago. The unbridled jingoism is out of this world (unlike Musk's rocket 
)
You just know if it was a Russian or a Chinese rocket that exploded they'd lose no time making fun of them, saying that their technology is outdated, Soviet-era crap, or cheap, inferior copies of Western designs, respectively.
)You just know if it was a Russian or a Chinese rocket that exploded they'd lose no time making fun of them, saying that their technology is outdated, Soviet-era crap, or cheap, inferior copies of Western designs, respectively.
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GarryB- Posts : 40558
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They better put lots of resources into the crew escape system moving forward.
It is interesting that the Americans claim to worry about human life but it was Buran that had the crew escape module and the US Space Shuttles that didn't.
It is interesting that the Americans claim to worry about human life but it was Buran that had the crew escape module and the US Space Shuttles that didn't.
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Big_Gazza- Posts : 4908
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Regarding safety, I find it absurd that SpaceX only conducted lift-off & landing tests until they managed to get a single test that could be called a success before shifting to full stack development. SN8, 9, 10 & 11 all failed catastrophically with total loss of vehicle, and even with the "successful" SN15 they had a fire in the engine bay, loss of tank pressure and an engine outtage. I mean for FFS, their vehicle has a landing technique that requires instant starting of 3x engines, subsequent flawless operation and performance of a flip to orient the vehicle for a tail-first controlled landing. If anything goes wrong, the vehicle will be DESTROYED and all occupants will be KILLED. No 2nd chance, no fly-around, no diverting to a secondary landings trip... you get a big KABOOM and up to 100 PAX obliterated. 
Does this sound like a practical transport system?
Furthermore, the Manned Dragon has its emergency crew escape rockets built into the capsule rather than on a jettisonable external tower like every single other manned space transport in history has done. The crew must go into orbit with 4x sets of hypergolic propellents on the other side of the pressure retaining bulkhead, and undergo the heat of re-entry hoping that these potential bombs don't leak and that the thermal protection of the rocket exhaust ports holds true... The test of the recovered LZ-1 capsule in 2019 resulted in explosion and catastrophic loss of the capsule that would have killed all occupants, but did SpaceX reconsider this bad design? Nope, they just pushed on and whitewashed the outcome rather than accept the delays of a re-design.
Yeah, I think its 100% safe to state that crew safety is not SpaceX primary consideration.
Does this sound like a practical transport system?
Furthermore, the Manned Dragon has its emergency crew escape rockets built into the capsule rather than on a jettisonable external tower like every single other manned space transport in history has done. The crew must go into orbit with 4x sets of hypergolic propellents on the other side of the pressure retaining bulkhead, and undergo the heat of re-entry hoping that these potential bombs don't leak and that the thermal protection of the rocket exhaust ports holds true... The test of the recovered LZ-1 capsule in 2019 resulted in explosion and catastrophic loss of the capsule that would have killed all occupants, but did SpaceX reconsider this bad design? Nope, they just pushed on and whitewashed the outcome rather than accept the delays of a re-design.
Yeah, I think its 100% safe to state that crew safety is not SpaceX primary consideration.
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Big_Gazza- Posts : 4908
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Imagery that shows what appears to be an explosive fragmentation from the BFG engine bay, accompanied by engine flare-up and subsequent failure. I suspect that this engine failure results in a sustained propulsion bay fire that sequentially disabled further engines and ultimately led to the loss of the stack.
It looks like Starshit lost at least 8 engines out of 32, probably more as the failure cascaded.
It looks like Starshit lost at least 8 engines out of 32, probably more as the failure cascaded.
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jon_deluxe- Posts : 15
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A summary of all the failures and the overall mission:
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lancelot- Posts : 3180
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This guy thinks the SpaceX Starship rocket was not the problem, but that the launch pad is totally retarded, cheap ass cost saving measure, which could have led to major injury in nearby towns had things gone slightly differently. He thinks the engines failed because of ejected debris from the poor launch pad design.
I agree with him with regards to the pad, but I would not bet on the rocket design being ok either. Not when Musk claims this rocket will be reusable 100 times and there is plenty of evidence that the engines eat themselves up on each flight.
I agree with him with regards to the pad, but I would not bet on the rocket design being ok either. Not when Musk claims this rocket will be reusable 100 times and there is plenty of evidence that the engines eat themselves up on each flight.
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Scorpius- Posts : 1576
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jon_deluxe wrote:It is surreal to see the press and large swathes of the internet lose their minds over a failed launch, celebrating over what was basically a failure like the ones that plagued the N1 program half a century ago. The unbridled jingoism is out of this world (unlike Musk's rocket
You just know if it was a Russian or a Chinese rocket that exploded they'd lose no time making fun of them, saying that their technology is outdated, Soviet-era crap, or cheap, inferior copies of Western designs, respectively.
The N-1 rocket had 4 tests of FOUR prototypes. What is the number of the Starship and Super Heavy test we saw this time? Elon Musk, if he were in Korolev's place, would have already been shot as a diversionist and saboteur for monstrous embezzlement. By the way, 15 years have passed since the first successful launch (2008) of a SpaceX rocket into orbit. For comparison, this is as much as it took between 1957 and 1972. During this period of time, the USSR went from launching the simplest satellite PS-1 to launching such missions as Salyut-1, Luna-20, and Venus-8.
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Hole- Posts : 11125
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They didn´t start from scratch, whole departments of NASA joined the company.By the way, 15 years have passed since the first successful launch (2008) of a SpaceX rocket into orbit.
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Big_Gazza- Posts : 4908
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SpaceX reuseable Falcon tech was developed by NASA, and handed over the SpaceX along with the engineers who developed it as part of the USGov ideology behind their crusade for privatising launch services. SpaceX rode on NASA coat-tails yet its fans and groupies love to disparage them for being "inefficient" or "unprogressive".
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In order to drive the US into a collapsing debt issue, Russia needs to invest heavily in the space competition effort alongside strategic arms development:
In Russia, work has begun on the creation of projects similar to Buran, by Kristina Tsytsura for VZGLYAD. 04.26.2023.
Borisov spoke about the conduct of research work to create projects similar to Buran.
Russia needs projects like the Soviet reusable return spacecraft Buran, research work is underway on this issue, said Yuri Borisov, Director General of Roscosmos, at the educational marathon “Knowledge. First."
According to the head of the state corporation, the projects are in a serious degree of practical implementation, TASS reports.
He added that such a project is now in demand, since only tens of kilograms of cargo can be returned from orbit. The problem of creating such a "shuttle" is the lack of finance.
https://vz.ru/news/2023/4/26/1209304.html
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GunshipDemocracy- Posts : 6172
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- Post n°940
Re: Russian Space Program: News & Discussion #4
GunshipDemocracy Wed Apr 26, 2023 10:40 pm
Amur-SPG rocket stage can be used more than 50 times
The stage of the new reusable rocket "Amur-SPG" can be used more than 50 times
The design of the Russian reusable methane rocket Amur-SPG started in 2020 by order of Roscosmos . It should be a two-stage medium-class rocket, the first launch of which from the Vostochny cosmodrome was originally planned in 2026. The carrier must have a reusable (up to 10 times) returnable first stage, equipped with RD-0169 engines that run on oxygen and liquefied natural gas (methane).
https://ria.ru/20230426/raketa-1867945714.html
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GunshipDemocracy- Posts : 6172
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- Post n°941
Re: Russian Space Program: News & Discussion #4
GunshipDemocracy Wed Apr 26, 2023 11:03 pm
Borisov said that Russia will use a nuclear tug in a joint project with China
https://tass.ru/kosmos/17619395
The head of Roscosmos explained that the tug will allow large objects to be delivered from near-earth to near-lunar orbit
MOSCOW, 26 April. /TASS/. The nuclear tug "Zeus" will be involved in a joint project with China of the international scientific lunar station. This was announced on Wednesday by Director General of Roscosmos Yuri Borisov at the educational marathon "Knowledge. First".
“We have a nuclear tug called Zeus. We are going to put it into practice by 2030. This is one of the products that will help in the expansion of the moon, we are going to use it in a joint project with China,” Borisov said.
According to the head of Roskosmos, the tug will allow large objects to be delivered from near-Earth to near-lunar orbit.
According to Borisov, China is interested in Russian rocket engines.
“We have an agreement with China on the creation of an international scientific lunar station, we are actively working. They are interested in our competencies in engines, they really want to get them and figure out how they are made in order to repeat them,” Borisov said.
According to the head of the state corporation, the Russian Federation has such relations with India, Roscosmos helps in organizing the first flight of a manned spacecraft into orbit.
At the end of 2022, Roscosmos announced the signing of a program for the development of cooperation in space activities for 2023-2027 with the Chinese National Space Administration (CNSA). In addition, the governments of Russia and China signed a cooperation agreement on the creation of an international scientific lunar station, the roadmap of which was presented in June 2021. According to the information provided, the construction of the station should be fully completed by 2035.
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GarryB- Posts : 40558
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The US space shuttle had rocket motors and an enormous external fuel tank that required two enormous solid rocket boosters to get it airborne and moving... the Soviet Buran the Shuttle was essentially a glider with no enormous rocket motors where all the rocket power and fuel was on the Energyia rocket that the Soviet Shuttle sat upon.
Rocket motors generate lots of high powered high velocity thrust and were really the only option for anything flying faster than mach 4 or more.
But now they have working scramjets they get essentially rocket motor thrust from a jet engine where the air can be scooped up as the vehicle travels through the air.
The options to replace the rocket motors with scramjets for certain parts of the flight would be rather interesting in terms of reducing weight of the entire platform.
Rocket motors generate lots of high powered high velocity thrust and were really the only option for anything flying faster than mach 4 or more.
But now they have working scramjets they get essentially rocket motor thrust from a jet engine where the air can be scooped up as the vehicle travels through the air.
The options to replace the rocket motors with scramjets for certain parts of the flight would be rather interesting in terms of reducing weight of the entire platform.
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- Post n°943
Re: Russian Space Program: News & Discussion #4
GunshipDemocracy Thu Apr 27, 2023 11:55 am
GarryB wrote:
But now they have working scramjets they get essentially rocket motor thrust from a jet engine where the air can be scooped up as the vehicle travels through the air.
The options to replace the rocket motors with scramjets for certain parts of the flight would be rather interesting in terms of reducing weight of the entire platform.
but dual system gets more complicated. The question is whether benefits outweigh drawbacks. Imagine descending you need to have extra weight to rocket boosters on orbit. And extra ablative protection. Let's see how the situation develops.
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But that is the thing, you could have variable rocket scramjets.... use oxygen in the first 30 seconds of flight and then let air intakes take over to provide the oxygen for burning the fuel in the atmosphere.... use a flatter trajectory to make the climb to orbit more shallow and then when you accelerate to an orbital speed that will hold you out of the atmosphere then zoom climb up to it.
In orbit your flight speed determines the altitude you orbit at, so say 10km/s gets you to a 30K km altitude you can fly through the atmosphere and accelerate to say 8km/s and then point your nose at a slightly upward angle and physically climb to say a 2k km stable orbit.
If you are in a stable 2k km orbit you can go higher by accelerating in you current direction of travel... when you reach 11km/s you can leave earth orbit completely... if you slow down in your direction of travel your orbital height is reduced.
If you are in a stable orbit and you want to climb to a higher you can't just point your nose away from the planet and fire a rocket to climb, because your orbital speed stays the same in your flight around the planet so you will climb but then you will fall back down past where you climbed from and bobble back and forward until you settle back to the same orbital height you were at before.
To climb you accelerate in your orbit to a higher orbital speed and you will start to gain distance from the planet and maintain that distance.
With a combined rocket/scramjet you can use the scramjet inside the atmosphere scooping up air as you go to burn the fuel meaning you save more than 75% of the weight of fuel and oxygen you need to carry. When you first lift off from the ground you will need oxygen pumped into the combustion chamber to get moving.
For a smaller spaceship you could be carried on the back of a Slon transport plane flying at 10km altitude at 700km/h when you are released and start up your scramjet to accelerate and perhaps climb to 30km altitude and then accelerate up to orbital speed... climb up out of the atmosphere... once you reach orbital speed and are out of the drag of the atmosphere then you should naturally climb to the orbital altitude that your speed allows you to maintain.
Then you can use your scramjet as a rocket thruster using some onboard liquid oxygen... or later perhaps if they can get powerful enough a ion thruster for in space to accelerate (climb) or decelerate (descend or reenter the atmosphere).
Not enough oxygen on Mars for use of a scramjet though.
And obviously you need to design a scramjet that runs up to orbital speed which is not easy of course... but the potential is enormous.
In orbit your flight speed determines the altitude you orbit at, so say 10km/s gets you to a 30K km altitude you can fly through the atmosphere and accelerate to say 8km/s and then point your nose at a slightly upward angle and physically climb to say a 2k km stable orbit.
If you are in a stable 2k km orbit you can go higher by accelerating in you current direction of travel... when you reach 11km/s you can leave earth orbit completely... if you slow down in your direction of travel your orbital height is reduced.
If you are in a stable orbit and you want to climb to a higher you can't just point your nose away from the planet and fire a rocket to climb, because your orbital speed stays the same in your flight around the planet so you will climb but then you will fall back down past where you climbed from and bobble back and forward until you settle back to the same orbital height you were at before.
To climb you accelerate in your orbit to a higher orbital speed and you will start to gain distance from the planet and maintain that distance.
With a combined rocket/scramjet you can use the scramjet inside the atmosphere scooping up air as you go to burn the fuel meaning you save more than 75% of the weight of fuel and oxygen you need to carry. When you first lift off from the ground you will need oxygen pumped into the combustion chamber to get moving.
For a smaller spaceship you could be carried on the back of a Slon transport plane flying at 10km altitude at 700km/h when you are released and start up your scramjet to accelerate and perhaps climb to 30km altitude and then accelerate up to orbital speed... climb up out of the atmosphere... once you reach orbital speed and are out of the drag of the atmosphere then you should naturally climb to the orbital altitude that your speed allows you to maintain.
Then you can use your scramjet as a rocket thruster using some onboard liquid oxygen... or later perhaps if they can get powerful enough a ion thruster for in space to accelerate (climb) or decelerate (descend or reenter the atmosphere).
Not enough oxygen on Mars for use of a scramjet though.
And obviously you need to design a scramjet that runs up to orbital speed which is not easy of course... but the potential is enormous.
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- Post n°945
Re: Russian Space Program: News & Discussion #4
GunshipDemocracy Fri Apr 28, 2023 1:35 pm
GarryB wrote:But that is the thing, you could have variable rocket scramjets.... use oxygen in the first 30 seconds of flight and then let air intakes take over to provide the oxygen for burning the fuel in the atmosphere.... use a flatter trajectory to make the climb to orbit more shallow and then when you accelerate to an orbital speed that will hold you out of the atmosphere then zoom climb up to it.
[]
And obviously you need to design a scramjet that runs up to orbital speed which is not easy of course... but the potential is enormous.
Theoretically it's almost possible
almost. Theoretical top speed for scramjet is ~25000km which is less the low orbit 28000 by 3000km/h Can you use a carrier plane? sure you can but there's no working solution so far...I guess there are reasons why.
Can you build a hybrid system with scramjet rocket and ion engines? you can but but probability of failure is so high that none is even considering it in practice. Perhaps in the future when technology advances?
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Scramjets would be useful in a winged-flyback booster tasked with lofting an orbital vehicle and its upper stage to a launch point at high altitude and hypersonic speed. eg a modernised version of the old Soviet "Spiral" spaceplane concept. Cruising at M4 @ 40kms altitude is a nice place to start ones climb to orbit 
The problem I see however is that while such could be a good low-cost launcher for small to medium payloads, development costs would be high, given that its essentially a hypersonic manned bomber with a satellite launcher on its back.
The problem I see however is that while such could be a good low-cost launcher for small to medium payloads, development costs would be high, given that its essentially a hypersonic manned bomber with a satellite launcher on its back.
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Theoretically it's almost possible Smile almost. Theoretical top speed for scramjet is ~25000km which is less the low orbit 28000 by 3000km/h
Well obviously getting to 25Kkm/h by scramjet will save massively on fuel weight because it means you don't need to carry three times the weight of your fuel in oxygen to get to that speed.
As I said a combined rocket scramjet you could get to the theoretical 25Kkm/h and then start injecting oxygen into the scramjet, essentially making it a rocket for the last acceleration to orbital speed and then shutdown.
Once in orbit you shut down the rocket/scramjet and use an ion engine to accelerate to any speed you want.
Can you use a carrier plane? sure you can but there's no working solution so far...I guess there are reasons why.
At the moment the options are limited... the An-124 has been proposed for all sorts of rockets and the An-225 would be useful, but as they are designing and building new heavy transports around the PD-35 engines the Slon aircraft modified with an H tail for large bulky loads on its back would be ideal to carry a small shuttle with a large fuel tank... the shuttle wont need to be as heavy as the Buran at about 110 tons and with a rocket scramjet instead of just a rocket it would only need a fraction of the weight of fuel.
Later a scramjet powered platform can be developed to accelerate to much higher altitudes and flight speeds for release.
Can you build a hybrid system with scramjet rocket and ion engines? you can but but probability of failure is so high that none is even considering it in practice. Perhaps in the future when technology advances?
If the US had working scramjets of course they would be working on it, but they don't.
A combination of Scramjets and Ion engines will be the future of space access... a carrier aircraft to get it airborne or a rocket with wings to return to an airfield after launch and then a scramjet to near orbital speed and then slush hydrogen fuel pumped into the scramjet for the last little push to get into orbit... once in orbit and out of the atmosphere then an ion engine would be the most efficient way to move around... if not particularly fast... very efficient.
The problem I see however is that while such could be a good low-cost launcher for small to medium payloads, development costs would be high, given that its essentially a hypersonic manned bomber with a satellite launcher on its back.
Who doesn't want to travel from Russia to South America in three hours?
Scramjets are jet engines and should not be as one use and fuel expensive as a rocket.
Up until recently the problem was we were using ramjets and not scramjets so the upper speed limits were mach 4 to mach 5 for the carrier platform.
With mature scramjet motors you can scale them up like jet engines and in terms of fuel demand they are probably more than a turbojet, but vastly less than a rocket and that increased fuel burn is countered by the fact that you are moving much much faster so the cost per km is probably not going to be too bad... probably Tu-144 to start with, but could come down... certainly Tu-144 like planes would become more affordable too... for shorter hops like one side of Russia to the other.
Can you build a hybrid system with scramjet rocket and ion engines? you can but but probability of failure is so high that none is even considering it in practice. Perhaps in the future when technology advances?
The core necessary technology is the scramjet, which they have obviously worked out for little missiles... how that translates to a larger platform and all the heat issues that creates is another matter.
Essentially supersonic flight needed the Turbojet, but eventually the low bypass Turbofan and indeed the ramjet made it affordable for military aircraft.
Scramjets will make supersonic flight affordable for civilian aircraft and commercial aircraft and will be a huge step forward for space access.
Converting space ports into big airports opens up more options and needing rather less liquid oxygen per litre of propellent makes things safer... if not safe.
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IMHO a huge technological leap will be if a variable cycle engine VCE can be developed that can transition between ramjet and scramjet mode. A vehicle could use turbojets (or better yet, detonation engines) to take off and achieve sufficient airspeed to ignite the VCE in ramjet mode, and then shift the engine progressively into scramjet mode as speed builds. For passenger vehicles the takeoff engines would be fixed (so available for emergency propulsion), but for automated space launch systems they could carried as jettisonable & recoverable pods to reduce the vehicle mass and improve performance once the VCE fires up.
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Location : New Zealand
The only difference between a ramjet and a scramjet is that the scramjet allows supersonic airflow through the hot section where the fuel is burned so essentially a scramjet is also a ramjet by definition but can produce more thrust because the airflow does not need to be restricted and slowed down to subsonic speeds in the combustion section.
This means a scramjet has massively more thrust at speeds approaching and exceeding the speed of sound.
A single turbojet that gets the aircraft airborne and flying could be used for takeoff and landing while in flight the intake for a central turbojet could close and the intakes for two or more scramjets could open with the scramjets starting up and accelerating the vehicle to top speeds... the airflow through a scramjet is much denser than with other types of jet engine because it does not need to be slowed down so even a rather small scramjet can deliver enormous thrust.
In the 1990s the Russians tested a small scramjet mounted on the nose of an SA-5 surface to air missile... the missile was launched and climbed to altitude and its solid rocket boosters fell away and the main rocket motor started up and accelerated the missile to mach 5 and quite high altitude of about 18km I seem to remember.
Then the nose mounted scramjet motor was started up and accelerated the entire missile to mach 6 and burned for about 2 minutes... during which the missile travelled just under 200km.
As you can see the nose mounted scramjet (early model) is actually rather tiny and with the solid rocket boosters gone the rest of the missile was quite a large load to carry for the engine... the fuel for the scramjet was located in the warhead and guidance section of the missile, but of course unlike the main rocket motor it only needed fuel... it did not need an oxidiser, so by weight 300kgs of fuel for the scramjet is the equivalent of 1.2 tons of fuel needed for a rocket motor to do the same thing.
The newer scramjets can go faster than mach 6 of course and will be different in that they have square or rectangular air intakes to make the airflow easier and simpler to control to ensure the fuel is burned even at supersonic speeds.
This means a scramjet has massively more thrust at speeds approaching and exceeding the speed of sound.
A single turbojet that gets the aircraft airborne and flying could be used for takeoff and landing while in flight the intake for a central turbojet could close and the intakes for two or more scramjets could open with the scramjets starting up and accelerating the vehicle to top speeds... the airflow through a scramjet is much denser than with other types of jet engine because it does not need to be slowed down so even a rather small scramjet can deliver enormous thrust.
In the 1990s the Russians tested a small scramjet mounted on the nose of an SA-5 surface to air missile... the missile was launched and climbed to altitude and its solid rocket boosters fell away and the main rocket motor started up and accelerated the missile to mach 5 and quite high altitude of about 18km I seem to remember.
Then the nose mounted scramjet motor was started up and accelerated the entire missile to mach 6 and burned for about 2 minutes... during which the missile travelled just under 200km.
As you can see the nose mounted scramjet (early model) is actually rather tiny and with the solid rocket boosters gone the rest of the missile was quite a large load to carry for the engine... the fuel for the scramjet was located in the warhead and guidance section of the missile, but of course unlike the main rocket motor it only needed fuel... it did not need an oxidiser, so by weight 300kgs of fuel for the scramjet is the equivalent of 1.2 tons of fuel needed for a rocket motor to do the same thing.
The newer scramjets can go faster than mach 6 of course and will be different in that they have square or rectangular air intakes to make the airflow easier and simpler to control to ensure the fuel is burned even at supersonic speeds.
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Big_Gazza- Posts : 4908
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Join date : 2014-08-25
Location : Melbourne, Australia
Point taken. Calling such an engine "variable-cycle" is probably overstated and "variable geometry" is likely a better descriptor. Kholod was a fixed geometry ramjet/scramjet demonstrator that was designed to operate over the M3.5-6.5 envelope, but any practical hypersonic vehicle will require engines operating over a much wider speed range, eg M0.8 - M6+, and any such engines would require controllable geometry of its intake, compression and combustion sections. Needless to say, this would be an extreme engineering challenge.
Indulging in speculation, I'd expect any such practical hypersonic vehicle to be quite large, likely as big as a Tu-160 (purely a guesstimate on my part) so getting it airborne and at an airspeed where the engines can start to operate will require a significant subsonic powerplant. It would require internally-mounted turbojets (or detonation engines) for minimal space requirement and high thrust (no bypass results in low efficiency but it isn't important for short running duration). Probably require variable geometry lifting surfaces to maximise lift at low takeoff speeds and thereby reduce the size of the takeoff engines.
BTW in its last tests the Kholod program was partly funded by NASA, and they have a publically-available document describing the vehicle - https://ntrs.nasa.gov/citations/19980137604
Good info for those interested in this subject.
Indulging in speculation, I'd expect any such practical hypersonic vehicle to be quite large, likely as big as a Tu-160 (purely a guesstimate on my part) so getting it airborne and at an airspeed where the engines can start to operate will require a significant subsonic powerplant. It would require internally-mounted turbojets (or detonation engines) for minimal space requirement and high thrust (no bypass results in low efficiency but it isn't important for short running duration). Probably require variable geometry lifting surfaces to maximise lift at low takeoff speeds and thereby reduce the size of the takeoff engines.
BTW in its last tests the Kholod program was partly funded by NASA, and they have a publically-available document describing the vehicle - https://ntrs.nasa.gov/citations/19980137604
Good info for those interested in this subject.
GarryB, kvs and jon_deluxe like this post