Correct, but the VLS did carry through to the produced design. While the missile guidance hardware was, AIUI, never installed, the VLS silo was built, and individual hatch covers installed, which are still present in this 2018 photo (albeit with a new satcom dome bolted on top!)
Sea Dart had an 11 Kg warhead that was located aft of the conical aerospike inside the component known as the forebody. While the forebody was approx 10 inch diameter this included a layer of insulation, required due to kinetic heating, so the useful diameter was maybe 8-9 inches. The W45 is reported to weigh 68kg which would made a real mess of the missiles weight and balance. As said before such a warhead would need to be located somewhere else on the airframe…. Which is difficult considering everything aft of the forebody was an annular section;- the air for the ramjet flows through a central tube approx 8 inches diameter.
The W81 seems to have been based on the Cougar primary, which shares heritage with the Cleo primary in the UK's PT.176. The shared first letter isn't a coincidence - note that Tsetse became Tony when Anglicised, and Python became Peter. In fact, there's some evidence that the multi-point initiation system used by both Cougar and Cleo was first developed at Aldermaston.
Also, linear implosion tends to be heavy for the yield, can't really get the proper squeeze on anything but a spherical primary.
5kt in the Talos. 0.5 KT for Tactical Atomic Demolition Munition.
The US Army 155mm nukes like the W48 will do.
Did the fissile material shortage caused by Windscale shutting down in 1957 last as long as that? The Magnox production plants at Calder Hall and Chapelcross came online between 1956 and 1960, and certainly by 1960 the MoD was cheerfully writing plans that called for several hundred warheads a year.
That would make sense. It also partly explains why the second half of Chapelcross wasn't built, and why the three commercial plants designed to run a military cycle were never used that way. By the time the wrinkles in production had been worked out, the need for a tonne or two of plutonium a year had gone away.
And they're still massively heavy.
The UK had been interested in the W54 - the UK version was 'Wee Gwen' - with an estimated weight of 50-55 lb and a yield of 37 tons. The W54 Mod 0 used on the AIM-26 Falcon was 50.9 lbs and had a yield of 250 tons; it's probably the closest match to what a Sea Dart warhead would require.
Gwen was certainly planned to be used with NIGS, see the bottom row of the table in this document from Brian Burnell's site:
That's the table I'm referring to... I've always read that as Owen, and figured it was some future warhead that hadn't been defined yet!
Apparently no further than a proposal.
Sea-skinming (it was the whole idea), but probably not too low. The first Sea Dart required target to be tracked constantly, so the missile must have a line-of-sight to at least some part of target. Given the intended max range of 37 km, it would require about 10-15 meters flight altitude against 15-meter tall target.
Seems that just the same semi-active homing, i.e. missile homed on target, illuminated by launching ship radar. With the range of about 37 km, there is no need for autonomous guidance.
No. As I said above - the guidance system was semi-active homing one, the same as on SAM Sea Dart. I.e. missile homed on radar echo from the target, illuminated by launching ship radar. It strictly limited the max range to the "within the horizon for launching ship".
Suppose the homing system problem is solvable. The question is whether engine/fuel/booster allows for that.
Well, if the homing system problem is solvable, then the rest is basically trivial. Problem is, that homing system is NOT simple.
Yes, BUT - if you solve the homing problem. To put it simply, there isn't much space in the missile nose for any kind of wide-angle gimballed sensor. The Sea Dart nose cone is almost completely inside the air intake - so either the homing system sensor must be VERY small (and thus inefficient) or it must be placed VERY deep (and thus have a very narrow view arc).
I wonder if any thought was put in it historically.
Apparently no. Looking at the description of the missile - it just have the usual Sea Dart semi-active homing seeker with interferometer antenna. And the small range of the missile made any kind of autonomous guidance redundant; why bother, if the missile is so short-ranged, that it could just home on echo from launching ships radar?
I rather doubt that. The Sea-skimmer is described as having 37 km range - which means, that target would be within the horizon for the launching ship. So why bother with autonomous guidance, if you could just illuminate the target with Type 909 radar & let the missile to home on it?
Because the range will inevitably be extended to beyond-the-horizon, and then you'll need to adopt the seeker. And whether it is possible would have been the first question literally anybody from the admiralty would ask the boffins the moment he sees the project.
Which means the missile does not occupy a very premium illumination channel.
Why bother, if the missile only have range to operate within the horizon? You need to fit a new seeker, an automomous autopilot - all the way battling the missile architecture limitations - to provide it with the capabilty it doesn't even need?
If you have a surface enemy within 37 km, it likely a top priority anyway.
