ZE419, a Sea King HAS5 that (temporarily) forgot how to fly

[Ascoteer]

Oh my!

I thought the prop housing on Albert was complex, but that is just mad!

Proper Steampunk so it is.

[Jessica]

Here's a look at a rotor blade in slow motion. The S-56 was the immediate predecessor to the Sea Thing, and used a similar rotor system.

Aren't you glad that they whizz around too fast for all that to be visible?

[Ex-FAAWAFU]

Jessica, you star! They used that film at Culdrose in ground school when we were learning thus stuff, and I have never been able to find it.

And I should perhaps ask whether some of you who genuinely seem to fear helicopters have warched equivalent film of "fixed" wings flexing & bending? If they didn't, they'd break and none of us would fly.

Edited August 22, 2016 by Ex-FAAWAFU

[At Sea]

Having flown on a few Military Helicopters and on countless Civil Airliners I can honestly say that I have more misgivings about Airliners.

I think it has a lot to do with being able to see what is going on in Military aircraft, where as Airliners keep it under wraps so well if the Pilot & co-Pilot were un-concious and you were heading for a mountain they'd keep serving drinks...

[Ex-FAAWAFU]

OK. Principles of rotary wing flight can wait, but I will attempt to explain why the Sea King rotor head is quite so complex.

The lines to lubricate the flying parts - the 3 hinges & damper, as above - are relatively simple. It's all the mundungus to get quickly from a flying machine to something that folds up neatly in a confined hangar, and back again, that add those squillions of pipes and wires.

I have already said that No 1 blade doesn't fold. The two either side of No 1 (Nos 2 & 5) fold flat along the spine to sit alongside No 1 when folded, but on the same level. The other two (Nos 3 & 4) fold back and downwards to sit at an angle along the side of the fuselage.

Ignore the folding tail; that is done manually.

So to get from this:

...to this:

...you need to:

a) pressurise the system. The Sea King has 3 hydraulic systems: Primary, which powers the flying controls; Auxiliary for back-up; and Utility for things like blade fold, rescue hoist, undercarriage etc. The Utility system runs at 3,000 psi (the other two at half that) and you don't want all that hydraulic pressure up on the head when you don't need it, so the first thing that happens is that the safety valve opens.

lock the flying controls (1,500psi hydraulics would easily bend your control rods if you allowed the cyclic / collective to move when the blades were folded) and then isolate hydraulics from the flying controls;

c) release the rotor brake;

d) position the 4 folding blades in the right position (centre them on all the hinges explained before, essentially);

e) turn the head so that No 1 blade is pointing straight back down the spine - it takes the shortest route, so can move in either direction;

f) re-apply the rotor brake;

g) withdraw the locking pins that keep the 4 folding blades in place when flying;

h) drive the gearing that folds the blades (I'll show you those as I model them) and move them under control (i.e. not just drop them);

i) once they are folded, lock the pressure in (using an accumulator) so that they don't move;

j) power down the system.

Clearly you don't want anything to happen out of sequence, so each phase is controlled via microswitches & sequencing valves that detect when, say, No 1 blade has reached the right position and move on to the next phase. Just to add to the fun, once this starts the 4 moving blades are completely independent of one another (because otherwise a problem with one blade could leave you with all 5 in odd positions; this way at least 4 of them will position right and leave you to sort the errant blade manually).

So apart from No 1 blade, each blade cuff has 4 or 5 microswitches and sequencing valves, plus the associated hydraulic lines and electrics to power them.

Given the fact that this was designed and engineered in the 1960s (actually, since the USN introduced the Sea King in 1961, probably even in the 1950s), it is a remarkably robust system. You occasionally got the odd sticking microswitch, so some poor bugger would have to climb up onto the head with a hammer and smack it while Flyco yelled at everyone to get the deck clear... but mostly it just worked. I never flew the Merlin, so cannot comment on its equivalent - but it certainly doesn't look as bonkers to the naked eye!

More soon - including some actual (gulp) modelling.

Crisp

P.S. Can anyone spot what is unusual about the Sea King that is running on deck?

Clue; at the time it was taken, the picture would probably have been secret because it shows something the wider public didn't normally see.

Edited August 22, 2016 by Ex-FAAWAFU

[moaning dolphin]

P.S. Can anyone spot what is unusual about the Sea King that is running on deck?

Clue; at the time it was taken, the picture would probably have been secret because it shows something the wider public didn't normally see.

Staring at it for ages and apart from the Grubber (Brown surcoat) with a chock in his hand, I cant see much wrong.......weapon stations? Although they are in the next phot as well.

Good simple description on the fold system, always a electrical problem if it went wrong, unless you had a shower of pink rain! The Merlin is much more dull. They have a control lock to lock the swashplate then each blade folds independently with its own electrical motor (that is probably still classified information so don't tell anyone!). If anything goes wrong it is definitely electrical and has the engineering fascination of a starboard flip flop.

Bob

[Ascoteer]

P.S. Can anyone spot what is unusual about the Sea King that is running on deck?

Clue; at the time it was taken, the picture would probably have been secret because it shows something the wider public didn't normally see.

IRCMs? MAWS?

[Ex-FAAWAFU]

The port forward weapon station is configured for the NDB - the clue is that triangle thing sticking out, which needed to be further out than for a Stingray because the Bomb is much fatter.

...the Grubber (Brown surcoat) with a chock in his hand...

God, I'd missed that. Engineer doing aircraft handling tasks; be very afraid (though nothing like as afraid as the other way round!) Edited August 22, 2016 by Ex-FAAWAFU

[Jessica]

Well that must mean Nuclear Depth Bomb, because I really doubt that a Non-Directional Beacon would be considered Secret...

[Ex-FAAWAFU]

Indeed. The WE177A nuke. It can't be that secret any more, cos I saw one (inert; don't panic!) at Old Sarum yesterday.

[Procopius]

Were there any guidelines on tactical employment of the weapon, out of curiosity? IE, was it only to be used on an enemy SSBN or SSGN, or was it expected that if you were using them, you'd be using them on any sub you could find (or could your sonar even distinguish between classes of sub with that level of fidelity)? And...were you expected to survive if you dropped one, or would it take the Sea King down as well?

[At Sea]

But don't mention WE118A...

[At Sea]

Were there any guidelines on tactical employment of the weapon, out of curiosity? IE, was it only to be used on an enemy SSBN or SSGN, or was it expected that if you were using them, you'd be using them on any sub you could find (or could your sonar even distinguish between classes of sub with that level of fidelity)? And...were you expected to survive if you dropped one, or would it take the Sea King down as well?

A very good mate of mine who is Ex-Trafalgar Class said that their job was to follow, harass, embarrass and ultimately sink enemy SSBN & to protect our SSBN from their SSN.

In the event of it all going off properly they reckoned within 24 hours the sheer volume of traffic though the gap would result in Nuclear depth charges being dropped on everything in the gap indiscriminately as our SSBN's were meant to be no-where near it.

So do your best lads until the RAF kill you with Nimrods...

[moaning dolphin]

Were there any guidelines on tactical employment of the weapon, out of curiosity? IE, was it only to be used on an enemy SSBN or SSGN, or was it expected that if you were using them, you'd be using them on any sub you could find (or could your sonar even distinguish between classes of sub with that level of fidelity)? And...were you expected to survive if you dropped one, or would it take the Sea King down as well?

I think you'll find that's classified....he could tell you but then he'd have to kill you!

[Jessica]

The interesting thing about lighting off a Nuke underwater is that most of the usual nuclear explosion effects we're so familiar with from films are absent. As long as you remain well clear of the water plume and don't go swimming at the explosion datum for a while, you're pretty much all right. The water absorbs most of the energy, radiation and thermal effects before they reach the surface unless the blast is very shallow (Think Castle Bravo for an example of a shallow explosion). If any water from the plume impacts you, you'll have to get decontaminated, but that's mostly the shower from hell and a good scrub down with nasty chemicals which would probably kill you faster than the radiation...

[Ascoteer]

Were there any guidelines on tactical employment of the weapon, out of curiosity? IE, was it only to be used on an enemy SSBN or SSGN, or was it expected that if you were using them, you'd be using them on any sub you could find (or could your sonar even distinguish between classes of sub with that level of fidelity)? And...were you expected to survive if you dropped one, or would it take the Sea King down as well?

Warload for a Grimrod would have been 6x Stingray torpedos and 2 Buckets of Instant Sunshine or 9 Stingrays. If we were working DS (Direct Support) then ideally we would prefer the Fleet use it's organic weapons, possibly under our direction. If working alone up threat then we would obviously use our own.

As to type of sub, it didn't matter as long as you had SACEUR's release (via COMAIREASTLANT via AOC 18 Gp for us). You could quite easily distinguish the class of sub from its noise signature (on nucs this is primarily powerplant noise) but not necessarily the exact type. I'm dredging my memory here but IIRC Victors and Charlies were in the same (sonic) class - Victors being SSNs, Charlies being SSGNs. I doubt we would have used it against a diesel boat (Kilo, Tango, Foxtrot) because they would never be able to outrun a torpedo.

As to actually using the Bucket of Instant Sunshine, then yes there were criteria that had to be met before you could drop. The Navy's criteria were different to ours because they used a British weapon whereas Grimrod carried an American weapon.

[andyf117]

Content withdrawn - I will NOT be threatened by a moderator, simply because I queried the actions of another...

Edited June 27, 2020 by andyf117

[Miggers]

IRCMs? MAWS?

Aha,the old Infra Red Control Mechanism and Multi Adjustment Wearing System.

Aren't they something to do with that Brown Shirt's trousers?,they look as though they've gone off his shoes and are at

half mast,so obviously he's not really checked his mirror in his quarters when getting dressed and used his IRCM and MAWS fit.

I knew I'd spot it......................(I'm off now before the Ascoteer get's her undies in a knot and gives me a clip about the lug'ole)

[moaning dolphin]

It was easier to wire up the weapon stations externally so when not in war mode everything could be removed. To route it internally would have been a mare because you have an Observer station on the inside and you don't want them catching their size 12 clodhoppers on the wires and dropping the weapon by mistake! Also the rear bit is where the final armament bit plugs in (I'm rambling abit because this is way out of my mechanical comfort zone! ). So when it drops it stays connected to the aircraft for a certain length and then that plug gets pulled out arming the weapon. I am assuming that the NDB would require an extra stand off for some reason.

Bob

[Ex-FAAWAFU]

OK, I'm struggling slightly with this....

The Forward Weapon Stations were located under the sponson attachments, and torpedoes/depth charges were carried inboard of the main undercarriage units.

So I don't quite get the correlation with the sticky-out-triangle-thing half-way along the fuselage, mid-point between the forward and aft stations....

....It doesn't look sturdy enough to hang a 600lb nuke on - or was it? You can tell me, as long as you don't then have to kill me, cut my head off, and put it in a safe!

Whilst on the subject of the weapons stations, perhaps someone can enlighten me - why and when did the wiring to them become external?

Looking at photos of HAS.1s and 2s, there isn't miles of bright red wiring all over the outside - that seems to have appeared on the HAS.5....

You are right; the actual body of the "Shape" (to hark back to Buccaneer / Scimitar terminology) would have been carried under the stub wing. But at the back of it (and indeed pretty much any weapon to be dropped into the sea from an aircraft) was a parachute; the triangular sticky out bit was the bit to which the parachute lanyard attached. See this lanyard (which is the back end of a stingray attached to the FAA Museum's Mk5). The parachute is inside that gold coloured tin can:

Moaning Dolphin is correct; the shape of the bomb meant that it stuck out further from the fuselage; the triangle thing was just to push the lanyard further out.

I think the red wiring was a Stingray thing; it is a much more sophisticated weapon than the Mk 44 / Mk 46 which it replaced, and you can tell it to do all sorts of clever things once in the water. HAS1s & 2s would only have carried 44s / 46s (in torpedo terms), but the HAS5 coincided with the arrival of Stingray. Bob is also right that Mk5s often removed the weapon carriers, depending on role, so it made much more sense to route the wiring externally. To be honest, the two aft weapon stations were somewhat for show, because by the time the Mk5 came along so much additional stuff had been added to the rear cabin that centre of gravity had become a real issue - we had to calculate it before every sortie to make sure we were within limits, and manage fuel accordingly. Two Stingrays that far aft would have given us serious problems, though technically it was still possible.

This shows a Stingray on an 820NAS Sea King 5 (indeed it is 014, though I am not sure whether it's the same airframe - we'd lost the stylised flying fish leaping through a ringbolt (the squadron's nickname was "Eight-Two-Ringbolt" for reasons lost in the mists of time) by the time I joined the squadron, so this pic is early-80s. Earlier radio fit; note the aerial on the nose. Also metal blades; you can tell by the shape of the blade root, which is different.

You can see the parachute, though not the lanyard:

Edited August 22, 2016 by Ex-FAAWAFU

[andyf117]

Content withdrawn - I will NOT be threatened by a moderator, simply because I queried the actions of another...

Edited June 27, 2020 by andyf117

[Ex-FAAWAFU]

This centre of gravity thing was a big deal. Look at this picture of a Mk1 in the hover (you can tell it's an HAS1 rather than a 2 because of the lack of "barn door" in front of the engine intakes, plus it was the only RN Mk with a 5-bladed tail rotor):

Slightly nose up, but basically pretty level.

Now look at a Mk 6:

Tail down, left wing low. They added the best part of a ton of extra weight down the back during the aircraft's life. The airframe stood up to it pretty well, on the whole - though in my era there were lots of Frame 290 cracks (frame 290 is the one to which the rear feet of the gearbox attach), and after my time there was another mod programme which added strengthening plates to the tail - these are often a feature of PE sets, though not in this build cos my cab was pre-mod.

Edited October 1, 2016 by Ex-FAAWAFU

[At Sea]

What is the purpose of the 'Barn Door'?

Does it protect from FOD damage?

Thanks.

[Ex-FAAWAFU]

Anyway, despite all this stuff, there has also been modelling going on. Mostly I have been doing stuff to fettle up the rotor head.

Take look at a real rotor head:

Specifically, look at the plate which leads from the pitch change rod (the stick with a blue tape at the top of it on the right) to the feathering hinge; the plate with a blue stripe in the middle of it.

Now look at the original Hasegawa after some fettling to remove seams and gaps:

Flat as a dull day in Norfolk.

So I have been using one of the most useful tools I possess, a micro chisel with a rounded end, to improve it a bit, then added a tiny bit of plastic rod:

Still some work to do to tidy things up, but getting there.

C

Edited August 22, 2016 by Ex-FAAWAFU

[Ex-FAAWAFU]

What is the purpose of the 'Barn Door'?

Does it protect from FOD damage?

Thanks.

Partly FOD protection, but mostly anti-icing; the things that look like white chevron shapes were a system for distributing anti-icing gunge whose name escapes me, but which stank hideous!