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

[Pete in Lincs]

I think we'd have been better off

all round dropping Rover Metro's

on Russian subs.

[Ex-FAAWAFU]

But the little whizzer at the back did push it along!

http://bemil.chosun.com/nbrd/files/BEMIL085/upload/2006/11/Sikorsky%20S-61%20with%20rotoprop.jpg

http://files.activeboard.com/1107929?AWSAccessKeyId=1XXJBWHKN0QBQS6TGPG2&Expires=1472688000&Signature=88p33DHP%2FhnrE%2BvSKnCPnQ9Bkl0%3D

That is awesome; I'd heard about it but never seen pictures.

But even that version needed a (non-pushing, conventional) tail rotor in the hover.

I'd be fascinated to see how much impact it had on the S61 performance. Retreating blade stall...?

Edited August 21, 2016 by Ex-FAAWAFU

[Ex-FAAWAFU]

Not strictly a 'galley', but RAF Sea Kings had facilities for hot drinks, at least.....

Effete, I tell you (& probably aimed at the rescued as much as the rescuers...).

Still, at least they had a lot of spare generating power; the No3 generator (the lump on the port side of the "dog kennel" transmission housing) was there to power a sonar, so it could probably handle the odd wet of tea!

[Ex-FAAWAFU]

Hmm. It appears I've just thread crapped all over you Crisp about MPA ASW.

I do apologise!

I shall shut-up now.

No problem.

4 pages into the build and almost no modelling at all...

But I did apply my first glue last night; pics later.

[TheBaron]

For the record, as a civvie I'm more than happy to earwig on a bunch of old sweats talking tech and tac. For me it's a valuable lesson in the realities behind the stuff I build.

Looking forward to those pics....

Tony

[Miggers]

Psst Miggers AVTUR, or rather, in the case of the FAA, AVCAT.

AVGAS is what Bulldogs burnt...

Cack!!!!

I know this,why the dickens did I type AVGAS(silly old twit Miggs).

Too late to edit,the rest of the FAA/RAF mob tooned into this latest of Crisp's and Deb's delves into their

respective memoirs will have read it by now..........

[wyverns4]

Ah, the smell of par-burnt AVTUR in the morning, (and any other part of the day),

Christian, exiled to a land without subs

[Bigdave22014]

No problem.

4 pages into the build and almost no modelling at all...

But I did apply my first glue last night; pics later.

What ?!?!

How dare you interrupt your own thread with some modelling?

I shall write to The Times. Where's my crayons?

[Dads203]

So a quick question for you Sea King chaps,

Being a born and bred Cornishman I used to see the 771 cabs flying around a lot, my Brother was attached

To 771 Sqn for his last few years in the Navy so I'm going to attempt to build one of the Sqn cabs in 72nd scale

Using the the Revell MK41 as the base kit and the Almark decals.

My brother was a clearance diver so I'm not sure of what role he actually did on the Sqn, I do know he made a few quid out of

Selling scallops though

I've found one picture of a 771 Sqn cab with a flir turret fitted behind the left hand sponson, seen these on the RAF HAR 3's

But not on the RN Sea Kings, was this a common fit fleet wide or a one off, I'm thinking that it was a late life upgrade

But pictures showing the fit are quite rare?

Link to the pictures:- http://www.fightercontrol.co.uk/forum/viewtopic.php?f=16&p=772852

Cheers for any info that you guys might be able to throw my way.

Dan

[Miggers]

AFAIK,the FLIR fit was late on in their career.

All the research I did(early Nortie's)when I did a 771 SAR cab(from the then new Revell HAS.6/AEW kit)didn't show a

FLIR turret up,so I didn't add one to mine.

Also I'm sure the Revell kit doesn't have one in it(though maybe the Mk.41 kit does).

Edited August 21, 2016 by Miggers

[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

[Dads203]

That's brilliant info , cheers chaps

[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]

I suspect blade stall was more of an issue on the S-61F/NH-3A:

http://storage.surfingbird.ru/l/15/1/15/3/r2_cs14110.vk.me_BnchyxpvF5c_315f211e.jpg

https://upload.wikimedia.org/wikipedia/commons/5/58/NH-3A_NAN8-65.jpg

http://www.sikorskyarchives.com/images/image%20s-66%20AAFS/S-66%20X%207.jpg

If you really want to know:

http://www.logbookmag.com/images/dload/fl/NH-3A.PDF

That's like putting 500bhp in a Mk2 Escort,no DTC or owt means far too much wheelspin for not enough grip

That's brilliant info , cheers chaps

You're welcome Dads.

[Ex-FAAWAFU]

That is indeed bonkers, though you can see where they are trying to get to / the areas of aerodynamics they are experimenting with.

As for the NH3A report, I suspect one of their limiting factors probably was RB stall, because they topped out at level flight at 211kts, which is not wildly different to G-LYNX's 216kts. At that speed, without the benefit of G-LYNX's BERP blades and their swept tips, they were almost certainly getting encountering issues with compressibility on the tips of the advancing blades, which puts significant stress on them.

Anyway, it rather misses the point of a helicopter. If you want to dash around at high speed, use a fixed wing!

[Ascoteer]

And there's me thinking RBS was someat to do with banking...

[moaning dolphin]

Theres far too much jovial commenting on here so I am now going to be a party pooper and talk about the model (what model!!!). Having posted the earlier pic of the rotor head I felt bad for Crisp so with a bit of a hangoer this morning I had a bit of coloury coloury therapy (as our old instructor would call it). Who needs these new fangled adult colouring books, when you could get an Aircraft Topic 1 (Maintenance manual) and colour in all those lovelly line drawings!

So after a bit of therapy I have hopefully cleared the fog a little

Above is number 5 blade (I hope!) with some of the relevent details covered. The orange lines around the cuff would be hydraulic lines and be silver in colour. The blue lines are the electrical wires and would be black, green lines are the lub lines and they would also be black. The green lines would be the same for all blades. The others would appear on the other 4 but in a different pattern. Below is #3 blade

To be honest if you did all 4 blades the same pattern (mirroring 2 & 5, and 3 & 4) I dont think anyone would notice apart from seasoned grubbers, and I certainly wouldnt say anything

Next is the damper wiring, again black tubing and this is the same for all blades (red colour)

And for those who are interested in how this miracle of engineering works I present this easy to follow diagram. Everything you need to know is there

Finally the flap restrainers and droop stops. First the droop stops (daglo bits, thumbs in, thumbs out, happy pilot!)

All you would be able to see really are the two paddle bits either side of the flapping restrainers, talking of which.....

Only thing missing is the spring around the middle tube, indicated in this side on view.....

And finally an exploded head just for interest!

Hopefully there is something for you to make use of. Looking forward to seeing your interpretation

Crack on young man your audience awaits

Bob

[Bigdave22014]

Bob, .....there's not going to be a test is there?

[Pete in Lincs]

If there is, I've got a note from my Mum.

[moaning dolphin]

Oh it's easy, latch pins, lock pins, control lock pins,if anything goes wrong it's the electricians fault!😁

[Ex-FAAWAFU]

Bob, you star; I will never be rude about Grubbers again. OK, that's probably a bit of a stretch; I will never be rude about THIS Grubber again...

Taken together with some other material supplied to me yesterday via PM, I reckon I now have all I need to do the head.

Thanks a lot!

[Pete in Lincs]

So now by page five you've got a head start?

Ahem

[Ex-FAAWAFU]

I said I'd try to explain some of this stuff...

The only reason the Sea King rotor head looks so complex is because of the blade fold. The ability to fold the blades automatically (i.e. without someone having to climb up onto the rotor head outside the aircraft), and thus clear the deck quickly, is vital on a carrier, and the Sea King was designed to fold from the outset. Folding is not a simple operation, but we will come to that (maybe in a separate post).

First, rotor heads 1.01.

A helicopter flies just like a fixed wing aircraft, in that an airfoil section generates lift because air flows over it at sufficient speed. In a fixed-wing, it's because the airfoil rushes along at high speed, and in a helicopter it's because the airfoil(s) spin round at high speed above your head (hence the expression "rotary-wing"; when all is said and done, they are still 'wings'). Result in both cases is lift - how much lift for a given shape depends mostly on speed and angle of attack.

If all a helicopter ever did was to go straight up and down, in theory you could have a completely fixed head; blades set at a given alpha (angle of attack), and the only variable would be the speed of rotation. [i say "in theory", because in practice the drag would probably break the whole rig at the blade root sooner or later.]

Since we want to do more than just go up and down, all rotor blades are able to move in three planes.

- They can feather (twist, just like a propellor blade), because that's the simplest way of giving the pilot control of the angle of attack;

- They can (seen from above or below) move from side to side; the requirement for drag is easy to understand (see above re avoiding shaking the thing to bits), the need to be able to lead is more complex, so see later; and

- They can flap up and down.

If you look at this rotor head (from a folded Wessex 1 at Duxford) you can clearly see the three hinges - with the dragging hinge also having a damper to stop it moving too far or fast).

And even simpler example is the Lynx, where the only visible hinge is the feathering hinge - flapping and drag are taken care of by flexing of the head, machined from a solid lump of titanium (that's why the aircraft is so manoeuvrable & why it is called a "semi-rigid" head):

Of course all this hinge malarkey needs lubrication. The Sea King has a single oil reservoir on top of the head that lubricates all 5 dampers and associated dragging hinges, plus a smaller reservoir on top of each blade which lubricates the feathering and flapping hinges.

So if you look at Moaning Dolphin's first pic above, the red lines at top left feed oil to the dampers, and the green lines feed oil to the flapping and feathering hinges.

EVERYTHING else up there is something to do with folding the blades.... of which more in a future post.

Hope that helps. I will explain why things need to flap, lead and lag if I ever pluck up the courage to explain rotary-wing theory of flight to you...

C

Edited August 21, 2016 by Ex-FAAWAFU

[Ex-FAAWAFU]

I wasn't completely fair in this post:

This is the Hasegawa rotor head:

Top:

This is a real Sea King rotor head (from a German cab judging by the stencils, but they are identical):

To make the comparison fairer I needed to add the parts for the blade cuffs (which are separate so allow options to build spread or folded cab):

That's the gluing; the cuffs are in upper and lower halves (and still need a LOT of cleaning up).

The cocktail stick is lined up with No 1 blade, which is the only one that doesn't fold.

Thrilling start, innit?

P.S. Even better; Hasegawa have given us a tiny damper reservoir on the top. You can see how much clean-up of nasty moulding seams is still to be done.

Edited August 21, 2016 by Ex-FAAWAFU

[TheBaron]

And if you're sat on top of it while it's going round:

http://foxtrotalpha.jalopnik.com/this-rotors-pov-video-shows-how-helicopters-dont-fly-b-1757858829