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Minimum altitude limit for missile which use ejection launch

Ronny

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There are two method of missile launch
The first is by rail launch, where missile is mounted on a rail and propelled straight forward
aim-9m_la_1594089315.jpg

The second method where missile are mounted by lugs and either dropped or ejected down before the engine propelled them forward
mfc-jassm-photo-03.jpg.pc-adaptive.full.medium.jpeg
Based on how they look, I assume that for the first method, there isn't any limitation of altitude, the missile can be launched even when aircraft is parked on ground, but how about the second method? is there are general limitation such as the aircraft must be at least 10 meters away from the nearest surface?
 

Grey Havoc

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I think it primarily depends on the missile and launch platform involved.
 

mkellytx

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There are two method of missile launch
The first is by rail launch, where missile is mounted on a rail and propelled straight forward
View attachment 650841

The second method where missile are mounted by lugs and either dropped or ejected down before the engine propelled them forward
View attachment 650842
Based on how they look, I assume that for the first method, there isn't any limitation of altitude, the missile can be launched even when aircraft is parked on ground, but how about the second method? is there are general limitation such as the aircraft must be at least 10 meters away from the nearest surface?
Some rail mounted missiles are zero / zero others not. Depends on the the missile and there are a lot of other parameters to consider. FWIW I remember reading an account of an Israeli ace who shot down a Mig-17 in the 6 day war. The Mig was flying less than 50 ft and the shooter was a Mirage III with AIM-9B's that was too low and the Mirage pilot waited for the Mig to cross a canyon before firing. Then you have Apache's shooting Hellfires hiding behind trees. The particulars of each missile tend not to be public...

Kind of you to put a picture of 5068 on your post, I conducted a mission where we dropped a JDAM out of the back bay at 1,500 ft AGL and .94 M. Typically speaking it will depend on the weapon. JASSM for instance, has a delay built in then a roll maneuver before deploying the wings to prevent it from flying back into the launching aircraft (which is generally a bad thing). Each weapon is different and has different parameters. Things come off different ways for different reasons which then dictate min altitude, again the specifics tend not to be public.

Dumb bombs limiting factor is leaving enough time for them to arm, the delay is there to prevent you from getting caught in the frag, also why they tend to be high drags for low releases

Cheers
 

Ronny

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Kind of you to put a picture of 5068 on your post, I conducted a mission where we dropped a JDAM out of the back bay at 1,500 ft AGL and .94 M. Typically speaking it will depend on the weapon. JASSM for instance, has a delay built in then a roll maneuver before deploying the wings to prevent it from flying back into the launching aircraft (which is generally a bad thing).
so for example with JASSM what is the approximate minimum height requirement? It appear to me that rocket propelled missile such as Exocet, ASM-3 can be launched from much lower altitude compared to turbojet weapon like JSM, JASSM right?
 

DWG

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It depends on how quickly the missile engine starts after launch, and how much altitude is lost in recovering to level flight. So it's going to specific to each missile design.

While in general engine ignition is going to be quicker for a rocket engine than a turbojet, the likelihood is that the rocket ignition is going to be in a nose-down attitude, propelling the missile lower, while a turbojet is likely to be in a shallower, potentially nose-up, glide by the time it gets the turbine spooled up, so thrust will more immediately work to bring it to level flight.

And a turbojet with a rocket booster is going to be a mix.

IOW it's complicated.
 

mkellytx

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so for example with JASSM what is the approximate minimum height requirement? It appear to me that rocket propelled missile such as Exocet, ASM-3 can be launched from much lower altitude compared to turbojet weapon like JSM, JASSM right?
That tends not to be public domain, people who know tend to sign NDA's and don't want to violate them. If you really what to know, suggest you find some videos of drops and count frames and do some basic physics calculations, it's a time honored open intel method.
 

Ronny

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It depends on how quickly the missile engine starts after launch, and how much altitude is lost in recovering to level flight. So it's going to specific to each missile design.

While in general engine ignition is going to be quicker for a rocket engine than a turbojet, the likelihood is that the rocket ignition is going to be in a nose-down attitude, propelling the missile lower, while a turbojet is likely to be in a shallower, potentially nose-up, glide by the time it gets the turbine spooled up, so thrust will more immediately work to bring it to level flight.

And a turbojet with a rocket booster is going to be a mix.

IOW it's complicated.
Good point, I wonder if T/W play any role too, JSOW-ER, MALD, SPEAR all use TJ-150 engine, but their weight is vastly different
 

AeroFranz

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Kind of you to put a picture of 5068 on your post, I conducted a mission where we dropped a JDAM out of the back bay at 1,500 ft AGL and .94 M. Typically speaking it will depend on the weapon. JASSM for instance, has a delay built in then a roll maneuver before deploying the wings to prevent it from flying back into the launching aircraft (which is generally a bad thing).

@mkellytx i'm looking at JASSM launches. Granted, this one is CGI, but I can't find the roll maneuver (see youtube video at 2:10).
Same with B-1 launch. Maybe it's more subtle than a full roll?
 

Ronny

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so for example with JASSM what is the approximate minimum height requirement? It appear to me that rocket propelled missile such as Exocet, ASM-3 can be launched from much lower altitude compared to turbojet weapon like JSM, JASSM right?
That tends not to be public domain, people who know tend to sign NDA's and don't want to violate them. If you really what to know, suggest you find some videos of drops and count frames and do some basic physics calculations, it's a time honored open intel method.
I looked at this video
JASSM started falling at 0.33 and start to climb up at 0.39, so it take around 6 seconds before it can balance and climb.
Maximum drop height is 176 meters
drop height.PNG
 

Ronny

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Kind of you to put a picture of 5068 on your post, I conducted a mission where we dropped a JDAM out of the back bay at 1,500 ft AGL and .94 M. Typically speaking it will depend on the weapon. JASSM for instance, has a delay built in then a roll maneuver before deploying the wings to prevent it from flying back into the launching aircraft (which is generally a bad thing).

@mkellytx i'm looking at JASSM launches. Granted, this one is CGI, but I can't find the roll maneuver (see youtube video at 2:10).
Same with B-1 launch. Maybe it's more subtle than a full roll?
This is the full roll I believe:
 

mkellytx

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@mkellytx i'm looking at JASSM launches. Granted, this one is CGI, but I can't find the roll maneuver (see youtube video at 2:10).
Same with B-1 launch. Maybe it's more subtle than a full roll?
Yeah, that's the danger of trying to remember things from 14-15 years ago, sometimes you mix up your airframes and full up rounds with safe separation shapes. JASSM's coming off of the shoulders of a BUFF HSAB should have a bit of roll (tend to think of the BUFF first). The video I was remembering was probably a safe separation shape coming off in disturbed air, sometimes it jumbles together after the years. My bad.
 

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Regarding the first test flight video above, understand that being a test, they might have separated both glide phase and powered flight to gather as much of data before engaging in the long cruise.
IMO in this video the engine was either turned on with a delay or from the result of a ground control command.

It would then be difficult to assess the free fall value.
 

AeroFranz

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@mkellytx , maybe you're thinking of some munition that is suspended 'upside down' with respect to the flight orientation? For example SDBs have the lugs in the belly, so IIRC it has to roll over after release.
 

mkellytx

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@mkellytx , maybe you're thinking of some munition that is suspended 'upside down' with respect to the flight orientation? For example SDBs have the lugs in the belly, so IIRC it has to roll over after release.
TBH after a while all of the different safe separation trials start to blur together, with the exception of the really cool ones or the ones where something went wrong.
 

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