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-   -   Chinook filling in the dam breach (https://www.pprune.org/military-aviation/624196-chinook-filling-dam-breach.html)

chinook240 3rd Aug 2019 07:18


Originally Posted by Roadster280 (Post 10535355)
Question for Wokka types...

Being ex-MAOT, I have spent rather a lot of time hooking loads etc under Wokkas, but it was 25 years ago. I *think* I recall that the Wokka had a special strop that released at the far end, rather than just the hook. Am I imagining that? Or was it just the center hook? Or a figment of my imagination?

First thing I noticed with this was that they were dropping 3 strops per lift, which is going to get expensive real quick. In my day, we'd have just sent the junior siggie to recover them, but in the duty of care age, if the dam breached and the lad went for a swim, that's a no-no. Of course I am jesting, we had a duty of care back then. But we'd still have recovered the strops :)

As I said above, I don’t think there are enough strops in the RAF for this lift and it looks like some kind of disposable version, I’ll ask the crews next week. Don’t remember a remote hook on a strop in SH use, I’ve seen them on civvy helos.

Easy Street 3rd Aug 2019 14:24


Originally Posted by T28B (Post 10535441)
also a discussion over at Rotorheads
https://www.pprune.org/rotorheads/62...-builders.html

...where someone asked whether it would be better to use 6 JetRangers instead of the Chinook 😂

cafesolo 3rd Aug 2019 15:48

Seen the Daily Wail yet? RAF SENDS IN DAM BOOSTERS.

Corporal Clott 3rd Aug 2019 19:28

It’s alright, they have flown in the PM now. He’ll sort it out...

https://cimg3.ibsrv.net/gimg/pprune....93b42413c.jpeg


Wander00 4th Aug 2019 14:30

Well at least so far as I have seen no one in the meeja has described the Chinooks as "Army " helicopters

langleybaston 4th Aug 2019 15:48

"RAF soldiers" in today's Telegraph.

Will the squadron become "The Dam Menders"?

Union Jack 4th Aug 2019 17:20


Originally Posted by cafesolo (Post 10535811)
Seen the Daily Wail yet? RAF SENDS IN DAM BOOSTERS.

Just keep the BBMF and 617 Squadron well away, especially any sign of the latter's badge.

Jack

Fareastdriver 4th Aug 2019 20:32

In the seventies there used to be what were called 'Border Closures'. This was when the Royal Engineers placed a steel tank across a road which was a, 'Non Approved Crossing' between Northern Ireland and Eire.

The tank was about 8''x2'' and for most roads this required two of them. The trick was to place two of these across the road, suitably protected by loads of sqaddies at every angle and them your trusty Pumas would come and pour concrete into the tanks.

A secure site some five or so minutes away would be the secure Redimix lorry site and the skips. each holding about a cubic yard of concrete, would be filled and hooked on the a six foot strop. Then we would fly to the border road, be talked on to the tank straddling the road and some lunatic would stand on the tank and pull the skip lever that would release a ton of concrete into the tank. The tank was on the border, we were invariably positioned so we were facing south or east so the skip was on the border and the cockpit was in Eire.

We could do a turnaround in about five minutes so 12 tons/hour was the filling rate which covered a normal closure.

etudiant 4th Aug 2019 23:48

Consider me skeptical. Sand bags do add bulk, but not strength or water impermeability.
The spillway cladding was clearly undercut and has given way, leaving the earthen dam below exposed..I'd note that the spillway appears poorly supported at best, probably not designed for heavy use.
If there is renewed rain, that expensively air lifted sand won't help.
What is needed is to lower the water level of the impoundment and a subsequent reconstruction of at least that part of the dam and the spillway.

SASless 5th Aug 2019 00:40


A secure site some five or so minutes away would be the secure Redimix lorry site and the skips. each holding about a square yard of concrete,
Depending upon the thickness of the concrete layer....that could be one very small or one very large Skip!

John Eacott 5th Aug 2019 02:58


Originally Posted by SASless (Post 10536823)
Depending upon the thickness of the concrete layer....that could be one very small or one very large Skip!

;)

No doubt a cubic yard?

I shifted many a kibble of concrete up in the Australian Alps, a tonne is roughly a third of a cubic metre and that was enough for the BK at 6,000ft AMSL thank you, even with a couple of aluminium kibbles to keep the weight down (they're normally of steel to cope with high-rise crane drivers). Always on a long line, though, at least 50'. The Wokka could be quite productive with a large Kibble and a fleet of Readimix trucks :hmm:


https://cimg4.ibsrv.net/gimg/pprune....68b6dc8473.jpg

https://cimg5.ibsrv.net/gimg/pprune....0ea4a6bdac.jpg

tmmorris 5th Aug 2019 06:10

That's why they are also pumping water out of the reservoir as fast as they can manage.

Stu666 5th Aug 2019 07:00


Originally Posted by etudiant (Post 10536809)
Consider me skeptical. Sand bags do add bulk, but not strength or water impermeability.
The spillway cladding was clearly undercut and has given way, leaving the earthen dam below exposed..I'd note that the spillway appears poorly supported at best, probably not designed for heavy use.
If there is renewed rain, that expensively air lifted sand won't help.
What is needed is to lower the water level of the impoundment and a subsequent reconstruction of at least that part of the dam and the spillway.

I think the whole point of the sand bags is to add weight to try and prevent the exposed section from bursting from within. Renewed rainfall probably not so much a threat now that they have pumps in place and have already lowered the water level considerably.

cats_five 5th Aug 2019 07:52


Originally Posted by tmmorris (Post 10536939)
That's why they are also pumping water out of the reservoir as fast as they can manage.

On TV this morning they were saying they can't pump too fast otherwise there could be a failure of the dam on the water side. Struck me they are pumping as fast as they can.

Whenurhappy 5th Aug 2019 08:01


Originally Posted by Herod (Post 10535271)
Lovely bit of PR. Now the public know we have an Air Force, can we increase the Defense Budget? No, I'm not waiting for an answer

Apart from regular media references to 'Army helicopter' and the infantile 'Army soldiers'.

Easy Street 5th Aug 2019 08:09


Originally Posted by etudiant
Consider me skeptical. Sand bags do add bulk, but not strength or water impermeability.
The spillway cladding was clearly undercut and has given way, leaving the earthen dam below exposed.

Impermeability is conferred by the clay core of the dam, which must still be in place or the dam would have given way on the night of the occurrence. The sand bags simply replace the (permeable) earth washed away after the spillway failed, the purpose of which is to hold the clay core in place by gravity. They do add strength and it’s a good repair as long as the broken part of the spillway isn’t overtopped again, which is why they started by placing a wall of sandbags at the top (with concrete grouting) to divert any water onto the good part of the spillway before pumping the level down. Removing the rest of the water is about reducing the load on the dam sufficiently for the temporary repair to be removed and placed with a permanent one.

BEagle 5th Aug 2019 21:06

I understood that the bags dropped by the Chinook are intended to provide something to which a stronger substance will be bonded once the Chinook lift is complete?

Easy Street 5th Aug 2019 21:54

The bags which were placed along the top of the spillway were reportedly sealed together with concrete, but those were fulfilling a different purpose, diverting water away from the damaged section while the threat of overtopping remained. The ones on the embankment are only providing mass; I read a report earlier where an engineer said they would need to be removed before a permanent repair was made (sorry, can’t find it again). There would be no point in repairing the spillway over the bags in that case.

Roadster280 6th Aug 2019 02:04


Originally Posted by Wander00 (Post 10536466)
Well at least so far as I have seen no one in the meeja has described the Chinooks as "Army " helicopters

They may be operated by RAF crews, but that is merely semantic. All JHC aircraft are under command of Army HQ.

melmothtw 6th Aug 2019 06:59


Apart from regular media references to 'Army helicopter' and the infantile 'Army soldiers'
Damn media!


Well at least so far as I have seen no one in the meeja has described the Chinooks as "Army " helicopters
Wait, what?


They may be operated by RAF crews, but that is merely semantic. All JHC aircraft are under command of Army HQ.
Oh now I don't know who to believe!


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