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<mailto: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