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  • desijatt
    Senior Member
    • Jul 2004
    • 126

    Cold Launch VS Hot Launch?

    What are the detailed differences and advantages/disadvantages also which one superior?
  • plawolf
    aggresive member
    • Jan 2000
    • 4543

    #2
    in a cold launch, the missile is ejected out of its container, usually by means of compressed gass iirc, before the rocket engine kicks in while the missile is in flight.

    a hot launch is when the missile propels itself out of the container usings its own rocket engine.

    the advanatge of using the cold launch method is mostly limited to naval applications. this is because with a cold launch, the warship does not need the complexted venting that a hot launch missile would require.

    the downside appears to be a limit on the number of missiles that can be fitted into a given space. all russian and chinese cold launched naval missiles use a circular design cell, which takes up more space per missile compaired to the square cell based design of american hot launch missiles batteries.

    other minor advantages for the cold launch missile might include:
    - slightly longer range as the missile does not use as much internal fuel to get off the ground.

    - better reaction time, re tor's missile nose pointing ability.

    disadvanatges may include:
    - limits to missile size on account of the pressure the missile container can withstand.

    - missile may face problems when launching in very windy conditions.

    as for which one is superior, well i dont think there is a clear cut answer, both have their own advanatges and disadvantages and its ultimately a decision based on the situations one is faced with.
    the true power of religion does not lie with the deity, it lies with the priests.

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    • sferrin
      Rank 5 Registered User
      • Apr 2005
      • 9981

      #3
      Originally posted by plawolf
      the advanatge of using the cold launch method is mostly limited to naval applications. this is because with a cold launch, the warship does not need the complexted venting that a hot launch missile would require..
      Using cold launch in a missile silo you can fit a bigger missile in the same silo and reload and reuse the silo fairly quickly in comparison to a hot launch. Also with mobile ballistic missiles you have less blast to deal with (although some hellacious recoil I'd imagine) On a surface warship I'd almost consider it a DISadvantage. What happens if you pop an S-300 into the air and it fails to ignite? That's several thousand pounds of propellant and warhead that is going to fall back on the deck.




      Originally posted by plawolf
      the downside appears to be a limit on the number of missiles that can be fitted into a given space. all russian and chinese cold launched naval missiles use a circular design cell, which takes up more space per missile compaired to the square cell based design of american hot launch missiles batteries...
      You also have to remember though that the SA-N-6 is quite a bit bigger than an SM-2. I doubt it would fit in a Mk41 VLS cell.



      Originally posted by plawolf
      other minor advantages for the cold launch missile might include:
      - slightly longer range as the missile does not use as much internal fuel to get off the ground.

      - better reaction time, re tor's missile nose pointing ability....
      The slightly longer range is probably going to be insignificant. TOR is good if you could be getting hit from ANY direction but a VLS ESSM isn't exactly lacking in turning ability right out of the vertical cell either. I'm not sure why the Russian facination with cold launch but it sure does make for some cool video





      Originally posted by plawolf
      disadvanatges may include:
      - limits to missile size on account of the pressure the missile container can withstand.

      - missile may face problems when launching in very windy conditions.

      as for which one is superior, well i dont think there is a clear cut answer, both have their own advanatges and disadvantages and its ultimately a decision based on the situations one is faced with.
      It doesn't seem to be a problem for SS-18s and SA-12s. (how big of a missile you can launch that is). Cold launching is probably more expensive. An advantage I can think of from the Russian point of view is you get the missile blast up in the air and away from the troops. Most western systems operate from fixed sites so it's less of an issue.
      A government that robs Peter to pay Paul can always depend on the support of Paul. - George Bernard Shaw

      flag@whitehouse.gov

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      • JonS
        Rank 5 Registered User
        • Jul 2004
        • 769

        #4
        the advanatge of using the cold launch method is mostly limited to naval applications. this is because with a cold launch, the warship does not need the complexted venting that a hot launch missile would require.
        Pla wolf the advatages apply to land based/silo ballistic missiles as well ie peacekeeper and so on.


        the downside appears to be a limit on the number of missiles that can be fitted into a given space. all russian and chinese cold launched naval missiles use a circular design cell, which takes up more space per missile compaired to the square cell based design of american hot launch missiles batteries.
        Actually there are many cold launch russian missiles that are not based on rotrary drum system ie brahmos/onyks and klub. And ofcourse they had many others in devolopment.

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        • GarryB
          Rank 5 Registered User
          • Jan 2000
          • 8678

          #5
          With cold launch if the missile has a problem it will explode outside the launcher.
          A cold launch method means less damage to the launcher and increases the rate at which the launcher can be reused.

          the advanatge of using the cold launch method is mostly limited to naval applications.
          Not having exhaust venting is an advantage in most applications.

          the downside appears to be a limit on the number of missiles that can be fitted into a given space. all russian and chinese cold launched naval missiles use a circular design cell, which takes up more space per missile compaired to the square cell based design of american hot launch missiles batteries.
          The launch tubes for the naval version of the TOR (KLINTOK) are arranged in a circular design, but the land based missile, which also uses vertical cold launch, has two packs of 4 x 1 cells for a total of 8 missiles in two rows of 4.

          In this case cold launch is very important as a hot launch would mean the missile was accelerating rapidly straight up, so a lot of energy would be wasted turning the missile into the direction it needed to go. With a cold launch nose mounted thrusters of relatively low power tip the missile in the direction it needs to fly before the main engine fires to send it on its way. Nose mounted rockets also fire to stop the missile flying into the ground due to the momentum of the nose.
          So cold launch allows the KLINTOK and TOR to be fired at close range targets from almost any angle.

          - limits to missile size on account of the pressure the missile container can withstand.
          Whether hot or cold launch the launch container has to take the force that pushes out the missile... in a cold launch the force is not very hot high velocity gas.

          - missile may face problems when launching in very windy conditions.
          Very windly conditions would effect any type of missile in any type of launch.

          What happens if you pop an S-300 into the air and it fails to ignite? That's several thousand pounds of propellant and warhead that is going to fall back on the deck.
          Regarding failures which would be worse... several thousand pounds of propellent and warhead detonating on top of a ships deck or inside it?

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          • GarryB
            Rank 5 Registered User
            • Jan 2000
            • 8678

            #6
            Regarding exhaust venting, if you are building a silo for an ICBM the size of an SS-18 and you want to harden it to 6,000 psi then not having to have the silo double the width the missile would normally otherwise need to allow for venting means you can make it smaller and much cheaper to make.

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            • sferrin
              Rank 5 Registered User
              • Apr 2005
              • 9981

              #7
              Originally posted by GarryB
              Regarding failures which would be worse... several thousand pounds of propellent and warhead detonating on top of a ships deck or inside it?
              Why would a missile explode while sitting in the magazine? Ordinance doesn't typically go off for no apparent reason.
              A government that robs Peter to pay Paul can always depend on the support of Paul. - George Bernard Shaw

              flag@whitehouse.gov

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              • Neptune
                Rank 5 Registered User
                • Oct 2005
                • 638

                #8
                The main advantages in cold-launch the Russian way, was its weight. The Klinok is reladen by seven to eight men, the container can be carried to the launcher and is put on a rail that is put on top of the launcher. Then it's slid down in its position. Something I have seen very rarely with a hot launch mechanism. And of course the system can be unladen and weight even less. Then the only thing there is just the top strengthened hatch and the underdeck support. For hot launch canisters, they have a lot of weigth themselves, even when unladen.
                Add to it that it's much cheaper to adjust a land-based system for naval applications this way as you don't entirely have to develop a new launcher, you just have the storage and launch cilinder which does the work. The ship's installation is kept to a minimum. (but that is not a real advantage typical for Cold Launch as not every navy uses derivates of land-based systems on ships.
                You can also ask why they don't use the Tor system instead of klinok. Well the answer is the same, the Tor reloads come in packs of four and are a lot heavier, not possible to reload these manually.
                Yet for other Navies that could be a possibility for the future though.

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                • GarryB
                  Rank 5 Registered User
                  • Jan 2000
                  • 8678

                  #9
                  Why would a missile explode while sitting in the magazine? Ordinance doesn't typically go off for no apparent reason.
                  Why would a missile explode after being catapaulted into the air and landing back on the deck?

                  Comment

                  • Neptune
                    Rank 5 Registered User
                    • Oct 2005
                    • 638

                    #10
                    I have seen that reason mentioned many and many times over, but the fact is that it doesn't happen. The missiles/canisters/storage containers are all equiped with test-mechanisms, once laden, the missile's status can be checked inside the canister. If something fails during that test, it just isn't being launched.

                    Comment

                    • danrh
                      Rank 5 Registered User
                      • Feb 2005
                      • 738

                      #11
                      Originally posted by GarryB
                      Why would a missile explode after being catapaulted into the air and landing back on the deck?
                      I think the point is that a hot launch requires the missiles rocket motor to burn in the launcher cell to generate the thrust for launch. In the early days particularly, solid rockets had a tendency to blow up due to less than adequate QC during manufacture. IIRC one of the major hypothese for the Soviet (Russian) use of cold launch systems rather than hot launch was the fact it took rather longer to get thier solid propellants to a sufficiently reliable stage.

                      Daniel
                      Warfare Sims

                      The Red Pill

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                      • koxinga
                        Senior Member
                        • Jan 2000
                        • 257

                        #12
                        Originally posted by GarryB
                        Why would a missile explode after being catapaulted into the air and landing back on the deck?
                        Cracked propellent for one, although relatively rare. Equally rare would be some kind of arming malfunction.

                        Re: CL, more complicated equipment, higher MTBF. Failure of CL gear WILL disable complete sections of the magazine, depending on how the plumbing works. Hence the so-called disadvantage of HL's complicated vents is relative as compare to CL.

                        Another way to examine failure scenarios it (below)

                        Rocket ignition failure: Probability?
                        CL: Missile falls back to deck, live ordnance on deck is a big no no.
                        HL: Live missile in launcher, still a risk but lesser

                        Cracked propellent: (explodes) Probability?
                        CL: Missile clear deck and explodes
                        HL: Missile explodes in launcher

                        Cracked propellent: (fizz) Probability?
                        CL: Missile clears deck, falls on deck, fizzes and burns on deck
                        HL: Missiles burns in launcher

                        Warhead premature activation: Probability?
                        CL: Missile explodes on deck
                        HL: Missile explodes in launcher/magazine

                        On the whole, it is a matter of preference. There are pros and con, IMO
                        Last edited by koxinga; 11th November 2005, 13:18.

                        Comment

                        • koxinga
                          Senior Member
                          • Jan 2000
                          • 257

                          #13
                          You know, on this topic, it reminded me of the old Cold War probability figures of successfully ICBM strikes. ie Failure to launch due to silo doors not opening, cold launch failure, lightning strikes on lift off, engine failure, guidance failures etc etc.

                          The probability figures were used to determine the min number of ICBMs :diablo: required for a effective deterrent.

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                          • sferrin
                            Rank 5 Registered User
                            • Apr 2005
                            • 9981

                            #14
                            Originally posted by GarryB
                            Why would a missile explode after being catapaulted into the air and landing back on the deck?
                            Because it was catepulted into the air and landed on the deck. Obviously.
                            A government that robs Peter to pay Paul can always depend on the support of Paul. - George Bernard Shaw

                            flag@whitehouse.gov

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                            • plawolf
                              aggresive member
                              • Jan 2000
                              • 4543

                              #15
                              Originally posted by sferrin
                              On a surface warship I'd almost consider it a DISadvantage. What happens if you pop an S-300 into the air and it fails to ignite? That's several thousand pounds of propellant and warhead that is going to fall back on the deck.
                              not sure about the russian ships, but the chinese 052Cs have their missile tubes fitted at an angle, meaning that the missile is propelled away from the ship. so if the engine fails to kick in, the missile should just fall into the sea.
                              the true power of religion does not lie with the deity, it lies with the priests.

                              Comment

                              • JonS
                                Rank 5 Registered User
                                • Jul 2004
                                • 769

                                #16
                                Originally posted by plawolf
                                not sure about the russian ships, but the chinese 052Cs have their missile tubes fitted at an angle, meaning that the missile is propelled away from the ship. so if the engine fails to kick in, the missile should just fall into the sea.
                                i doubt that unless the ship is standing still even then its not possible unless the missile is ejected like 40 or 50 meters horizontally which is never the case.

                                Comment

                                • plawolf
                                  aggresive member
                                  • Jan 2000
                                  • 4543

                                  #17
                                  Originally posted by JonS
                                  i doubt that unless the ship is standing still even then its not possible unless the missile is ejected like 40 or 50 meters horizontally which is never the case.
                                  how did you come up with 40 or 50m?

                                  looking at this picture, the distance between the missile hatches and the side of the ship is only a handful of metres.

                                  even if the cold launch doesnt have quite enough power to send the missile all the way over the side, the missile would at worst only strike a glancing blow on the side railing of the ship. might need a new paintjob, but its not likely to cause much damage.
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                                  the true power of religion does not lie with the deity, it lies with the priests.

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                                  • KJlost
                                    Rank 5 Registered User
                                    • Jul 2004
                                    • 297

                                    #18
                                    While a there is a bit of time before it actually enters service, South Korea will be deploying cold-launch VLS on KDX-2 and KDX-3 ships alongside Mk41s for launching anti-sub missiles and cruise missiles. The advantage being listed is the slight increase in range due to the launch method and less possible wear and stress that comes from rocket exhaust among others.

                                    The design, from what I could tell from the Mk41 arragement on Wang Gun and models of KDX-3, isn't circular, so that's not a problem. There are two ways to solve the rocket exhaust failure problem, which is angling the launchers outboards so the projectile would go overboard as it is launched. This is the most simple method, but not very space-efficient. Another is using control rocket motor to simple blow the missile overboard as it is being launched. From what I can tell, KM-SAM (land-based SAM system, also using cold-launch method) and the anti-sub missile uses this technique, suggesting that Korean VLS system is up-upright in their installation.

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                                    • GarryB
                                      Rank 5 Registered User
                                      • Jan 2000
                                      • 8678

                                      #19
                                      Because it was catepulted into the air and landed on the deck. Obviously.
                                      Is that why you don't have to pull the pin on hand grenades for them to explode?

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                                      • sferrin
                                        Rank 5 Registered User
                                        • Apr 2005
                                        • 9981

                                        #20
                                        Originally posted by GarryB
                                        Is that why you don't have to pull the pin on hand grenades for them to explode?

                                        Are you saying you don't know the difference between a hand grenade and a three thousand pound missile?
                                        A government that robs Peter to pay Paul can always depend on the support of Paul. - George Bernard Shaw

                                        flag@whitehouse.gov

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