The end development of the arm launchers was the Ticonderoga
class’ Mk26 twin arm launcher so let’s look at the advantages and disadvantages
of both the Mk26 arm launchers and the Mk41 VLS.
Arm Advantages
Pointing. The arm
launcher points directly at the target and the missile launches horizontally
rather than vertically. This means there
is no delay while the missile tips over and acquires the target. Therefore, the missile gets to the target
faster than it would from a vertical launch system.
Magazine Protection.
Because the missiles are stored below deck, presumably in an armored
magazine, the missiles are better protected.
Deck Space. An arm
launcher requires very little deck space as opposed to a VLS which is spread
out over a large deck area.
Arm Disadvantages
Single Point of Failure.
An arm launcher represents a single point of failure. If the launcher is rendered non-functional
for any reason, the entire missile capability is unusable. Obviously, with two launchers, the remaining
launcher could continue to function.
Firing Arc. Arm
launchers have a limited firing arc because the ship’s superstructure masks
portions of the firing arc. Assuming the
ship has time to maneuver to unmask its launchers, which would almost always be
the case, this is not a serious drawback but it is still a limitation.
VLS Advantages
Missile Availability.
In a VLS system all of the missiles are immediately available for use.
Maintenance. Missiles
are supplied as sealed canisters which minimizes maintenance.
Simplicity. A VLS
system is mechanically simpler and more reliable.
Missile Size. A VLS
is capable of launching larger missiles such as Tomahawks. The Mk41, for example, was supplied in three
sizes to accommodate different missile sizes although, currently, only two
sizes are offered. To be fair, this
advantage comes at the cost of more internal ship’s volume being consumed which
is a disadvantage.
VLS Disadvantages
Tip Over. The
vertical launch requires that the missile travel straight up (90 deg off the
target vector) after launch and then tip over to the horizontal and acquire the
target. This delay means that it takes longer
to get to the target. This delay could
prove critical when using ESSM at shorter ranges or against supersonic missiles
when every second counts in terms of the number of engagement attempts
possible.
Exposure. The entire
missile inventory is exposed at deck level and is unarmored from above which
renders the ship’s entire missile inventory more susceptible to battle damage.
Launch Failure.
Vertical launch systems are susceptible to damage from a failed launch
due to either a restrained (obstructed) launch or fallback if the missile
engine fails/explodes during launch.
This exact scenario happened to the US Burke class destroyer The
Sullivans, just recently, and to the German ship Sachsen a couple years
ago. Both ships were damaged and set afire. In contrast, a failed launch from an arm
launcher results in the missile being ejected over the side of the ship rather
than falling back on the ship. Any
initial motor explosion would occur off the side of the ship and debris/fire
would not fall back on the ship.
Neutral
Firing rate. It is a
common belief that the VLS has a much faster firing rate than an arm
launcher. However, the useful, effective
firing rate for arm launchers pretty well matches the VLS. The Mk26 twin arm launcher could launch two
missiles every 9 seconds. For ships such
as the early Ticonderogas and the Virginia class cruisers, both of which
mounted two launchers, one fore and one aft, that equates to 4 missiles every 9
seconds or a missile every 2.25 seconds.
Given the Navy’s typical shoot-shoot-look engagement sequence, a missile
every 2.25 seconds is adequate for nearly any scenario. Today’s VLS really offers little in the way
of an effective enhanced firing rate.
Illustrative Examples
The Perry class frigates had a Mk13 single arm launcher with
a 40 missile magazine. By comparison,
we’re struggling with today’s frigate designs to get 32 VLS cells to fit into a
design. The US Navy’s new frigate
design, for example, is spec’ed at 32 VLS cells, a 20% decrease in capacity
from the Perry class!
As noted, the Virginias and early Ticonderogas had 2x rapid
fire Mk 26 twin arm missile launchers mounted fore and aft. A pair of missiles (one on each arm) could be
launched every 9 seconds. Thus, the
ship’s overall firing rate was 4 missiles every 9 seconds (a missile every 2.25
sec) – a respectable rate and quite adequate for almost any scenario. Given the Navy’s typical shoot-shoot-look
engagement sequence, this rate of fire seems perfectly adequate.
The Burke class carries 96 VLS cells which provides enough
missiles for air defense (especially with ESSM quad packing) and a useful
quantity of Tomahawk cruise missiles. To
be fair to the arm launchers, that number of missiles was not believed
necessary at the time. Had more missiles
been deemed desirable, a third launcher could have been added or the existing
standard missile magazine could have been enlarged.
Summary
The table below summarizes the advantages and disadvantages
of both systems. As seen, neither has an
overwhelming advantage. The choice of
which system to select depends on which factors one chooses to prioritize.
Arm
|
VLS
|
|
Firing Rate
|
-
|
-
|
Time To Target
|
ü
|
|
Reliability
|
ü
|
|
Magazine Survivability
|
ü
|
|
Minimal Deck Space
|
ü
|
|
Firing Arc
|
ü
|
|
Larger Missiles
|
ü
|
|
Missile Availability
|
ü
|
|
Maintenance
|
ü
|
|
Launch Failure Damage
|
ü
|
You can decide for yourself which system you prefer but the
key finding in this post is that the supposed superiority of the VLS is nowhere
near the absolute given that everyone believes. In fact, for the most common surface to air engagement
scenario that we’ve documented in previous posts – an incoming missile first
engaged at the horizon with ESSMs – an arm launcher which can point directly at
the target and get missiles to the target faster may well be the better choice.
(1)Wikipedia, “Mk26 Missile Launcher”, retrieved 3-Apr-2020,
https://en.wikipedia.org/wiki/Mark_26_missile_launcher