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Newbie questions Rail / Ejector launchers



 
 
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  #1  
Old November 10th 03, 09:10 AM
AL
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Default Newbie questions Rail / Ejector launchers

Hi,
Here is a newbie question.

What are the merits and the pitfalls of rail vs ejector launchers
for guided missiles? I suppose bombs have to be ejector launched and
rockets rail.

Whenever I visit an airshow, I ended up scratching my head.



--
AL
New anti-terrorism tool, "Fly naked"
http://www.alfredivy.per.sg

  #2  
Old November 10th 03, 09:30 PM
peter wezeman
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AL wrote in message ...
Hi,
Here is a newbie question.

What are the merits and the pitfalls of rail vs ejector launchers
for guided missiles? I suppose bombs have to be ejector launched and
rockets rail.

Whenever I visit an airshow, I ended up scratching my head.


Ejectors are used to place a missile or bomb far enough away from the
aircraft so that they are in relatively undisturbed airflow. This has been
required on every fighter that carries missiles in an internal weapons
bay, such as the F-102, F-106, YF-12, and the new FA-22. Ejectors are
also often useful for external stores to get the weapon clear of the
complex flow field near the aircraft. Extensive tests are carried out
for any new aircraft or new store to determine the separation behavior
and what type of ejector is required for it. I have a vague memory that
the F-14 required especially powerful ejectors to ensure clean separation
of bombs carried under the fuselage, as the fuselage of that aircraft is
a lifting body and stores are subjected to aerodynamic forces that tend
to push them up against the aircraft. I think it was also an F-14 that
shot itself down when the ejector for a Sparrow missile failed and the
missile lit off while still held in its recess.

Hope this helps,
Peter Wezeman
anti-social Darwinist
  #3  
Old November 10th 03, 10:34 PM
Jeff Crowell
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peter wezeman wrote:
I think it was also an F-14 that
shot itself down when the ejector for a Sparrow missile failed and the
missile lit off while still held in its recess.


Dunno about the above, but a Tomcat shot itself down when
a (properly functioning) Sparrow fired from one of the after
recesses pitched up while still under the aircraft, and struck the
underside of the big Grumman bird. This led to the
development of a new mark of Sparrow (AIM-7P?) which
further delayed pitchup to allow more runout.


Jeff


  #4  
Old November 11th 03, 12:56 AM
Pete
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"AL" wrote in message ...
Hi,
Here is a newbie question.

What are the merits and the pitfalls of rail vs ejector launchers
for guided missiles? I suppose bombs have to be ejector launched and
rockets rail.

Whenever I visit an airshow, I ended up scratching my head.



A general rule for missiles might be:
Ejector racks next/on the fuselage
Rails away from the fuselage. underwing and wingtip.

Ejector racks kick the missile out from the fuselage to get out of the
airflow, to clear other protuberances (other missiles, etc) and also to
limit the burn effects from the missile motor.

Consider if the F-4/Sparrow were on rails. The front missile can't launch
without burning the aft missile, and the aft missile can't launch because
the front missile is in the way.
(Not counting the fact that two of the fins are recessed into the fuselage,
and the missile body itself is in a slight recess)

Pete


  #5  
Old November 11th 03, 05:43 AM
Bob Martin
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Consider if the F-4/Sparrow were on rails. The front missile can't launch
without burning the aft missile, and the aft missile can't launch because
the front missile is in the way.
(Not counting the fact that two of the fins are recessed into the

fuselage,
and the missile body itself is in a slight recess)


Originally the plan was to use rails that swing down... the front missiles
were on a trapeze system, and the aft ones were on arms that swung down from
an inboard hinge (parallel to roll axis). That got scrapped halfway through
the design process.


  #6  
Old November 11th 03, 05:46 AM
WaltBJ
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F102 had rails for missiles and tubes for rockets. 3 each RX tubes
were in each of the center four doors. MX rails were pneumatically
extended and retracted. The firing cycle was thus: Doors snapped open,
rear (3) rails extended, 3 missiles fired, front rails snapped down as
rears retracted, front 3 missiles fired, front rails came up, doors
snapped closed - all in 3 seconds flat. Everybody was extremely
respectful of extended doors on the ground especially with HP
pneumatic (3000PSI) system charged. Special clamps held doors extended
when working around the Deuce in this condition.
Walt BJ
  #7  
Old November 11th 03, 05:55 AM
Pete
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"WaltBJ" wrote in message
om...
F102 had rails for missiles and tubes for rockets. 3 each RX tubes
were in each of the center four doors. MX rails were pneumatically
extended and retracted. The firing cycle was thus: Doors snapped open,
rear (3) rails extended, 3 missiles fired, front rails snapped down as
rears retracted, front 3 missiles fired, front rails came up, doors
snapped closed - all in 3 seconds flat. Everybody was extremely
respectful of extended doors on the ground especially with HP
pneumatic (3000PSI) system charged. Special clamps held doors extended
when working around the Deuce in this condition.
Walt BJ


Right. Rails for missiles held internally. Same as the -106.

IIRC, a guy at Loring lost part of his arm putting the downlocks on a bird
coming back from an alert mission. You had to put the locks on prior to
shutdown, and with the doors open. Fault in the system caused a door-close
just as he was putting on one of the locks.

There is no possible way to move fast enough to avoid the doors snapping
shut.

Pete


  #8  
Old November 12th 03, 12:17 AM
Vygg
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Default



peter wezeman wrote:

AL wrote in message ...

Hi,

Here is a newbie question.

What are the merits and the pitfalls of rail vs ejector launchers
for guided missiles? I suppose bombs have to be ejector launched and
rockets rail.

Whenever I visit an airshow, I ended up scratching my head.


Ejectors are used to place a missile or bomb far enough away from the
aircraft so that they are in relatively undisturbed airflow. This has been
required on every fighter that carries missiles in an internal weapons
bay, such as the F-102, F-106, YF-12, and the new FA-22. Ejectors are
also often useful for external stores to get the weapon clear of the
complex flow field near the aircraft. Extensive tests are carried out
for any new aircraft or new store to determine the separation behavior
and what type of ejector is required for it. I have a vague memory that
the F-14 required especially powerful ejectors to ensure clean separation
of bombs carried under the fuselage, as the fuselage of that aircraft is
a lifting body and stores are subjected to aerodynamic forces that tend
to push them up against the aircraft. I think it was also an F-14 that
shot itself down when the ejector for a Sparrow missile failed and the
missile lit off while still held in its recess.

Hope this helps,
Peter Wezeman
anti-social Darwinist

The F-106 and F-102 used rails, not ejectors for the AIM-4. Only the AIR-2A was "ejected" from the bay.


Vygg



  #9  
Old November 12th 03, 02:41 AM
AL
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Posts: n/a
Default



Pete wrote:

"AL" wrote in message ...


Hi,


Here is a newbie question.

What are the merits and the pitfalls of rail vs ejector launchers
for guided missiles? I suppose bombs have to be ejector launched and
rockets rail.

Whenever I visit an airshow, I ended up scratching my head.



A general rule for missiles might be:
Ejector racks next/on the fuselage
Rails away from the fuselage. underwing and wingtip.

Ejector racks kick the missile out from the fuselage to get out of the
airflow, to clear other protuberances (other missiles, etc) and also to
limit the burn effects from the missile motor.

Consider if the F-4/Sparrow were on rails. The front missile can't launch
without burning the aft missile, and the aft missile can't launch because
the front missile is in the way.
(Not counting the fact that two of the fins are recessed into the fuselage,
and the missile body itself is in a slight recess)

Pete




So a AIM-9 when mounted on the fuselage willl be ejector launched or are
they limited by design?

--
AL
New anti-terrorism tool, "Fly naked"
http://www.alfredivy.per.sg


  #10  
Old November 12th 03, 04:15 AM
Bob Martin
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So a AIM-9 when mounted on the fuselage willl be ejector launched or are
they limited by design?


All AIM-9's are rail launched. Fuselage mounting of one would require a
short pylon and a rail attached to it.


 




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