The SM2 fired from the Antietam in the video is not a vectored thrust
missile and it turns damn fast. The sea sparrow dose turn faster I'm
sure and I did not know it had vectored thrust (I see it does have
vectored thrust via fins in the exhaust) but it can not be fired from
the Mark 42 system on the Antietam anyways. It uses the Mark 41 firing
system.
Regardless modern missiles have been turning very fast since the 80's,
this is not new.
Monroe
-------- Original Message --------
Subject: [AR] Re: Turning after launch
From: George Herbert <george.herbert@xxxxxxxxx>
Date: Tue, April 17, 2018 3:04 am
To: arocket@xxxxxxxxxxxxx
ESSM has vectoring thrust and vertical launches most of the time, so the
ability to turn that fast is mission critical...
-george
George William Herbert
Sent from my iPhone
On Apr 16, 2018, at 4:29 PM, Barry Murphy <barrydmurphy@xxxxxxxxxxx> wrote:
The Evolved Sea Sparrow Missile, ESSM, can perform an incredible 90 degree
turn as seen mid way through this clip.
https://m.youtube.com/watch?v=Qd2U_jOqzsA
In the naval warfare context, missiles like the ESSM are referred to as
"point defense." Whereas the Standard family of missiles (SM-2), as seen
in the clip Monroe posted, are an "area defense" weapon.
Point defense is mainly protection against sea skimming anti-ship missiles
hence the sharpe 90 degree turn that the ESSM can perform. The ESSM can
also target low flying helicopters and aircraft. The Royal Canadian Navy
has adapted it to target small surface targets at close range, a major
vulnerability for warships when operating in today's hotspots.
Barry
On Apr 16, 2018, at 13:35, Henry Spencer <hspencer@xxxxxxxxxxxxx> wrote:
On Mon, 16 Apr 2018, John Dom wrote:
Even space launches would start turning almost immediately -- look at
the videos of Apollo LM ascents from the Moon -- were it not that their
final velocities are so high that they have to get completely clear of
the atmosphere fairly early.
Isn't that called a gravity turn considering orbital/space launches.
Not exactly -- a gravity turn is a specific type of turning trajectory
which happens to be a good approximation to the atmospheric part of
launcher trajectories. The LM ascent trajectory, with no atmosphere to
worry about, was *not* a gravity turn, because gravity turns are not in
fact optimal for orbital launch. (They're not too far from optimal, but
the LM needed every little bit of advantage it could get.)
Those are slow
The ones normally used for launchers are slow. Gravity turns don't have
to be slow. And the turn the LM used was not; it was done fairly quickly,
after a brief vertical ascent to assure terrain clearance.
and have little to do with the speedy trajectory switch observed
with SAMs or cruise missile launches.
As I indicated, the difference is because of different requirements. SAMs
aren't going to accelerate to 8km/s, so they don't need to gain lots of
altitude rapidly to clear the atmosphere. Cruise missiles don't want to
gain altitude at all.
This quick turn was not done say 10 years ago looking at YouTube.
Doing such a sharp turn so early generally requires vectored thrust,
because a vertically-launched missile doesn't have enough airspeed then to
make such a hard turn with fins. Early vertical-launch missiles -- mostly
converted from designs built for more traditional launch setups -- didn't
have suitable thrust vectoring, and so had to delay their turns somewhat;
the need was only identified after experience with early vertical-launch
missile arrays.
Henry