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RAF go from Dambusters to Dam builders

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RAF go from Dambusters to Dam builders

Old 2nd Aug 2019, 10:16
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RAF go from Dambusters to Dam builders

This is not the first time the RAF have been called in recently to assist with flood problems.

https://www.bbc.com/news/uk-england-derbyshire-49199505

Emergency crews are racing to save a damaged reservoir, as "terrified" residents fear their Derbyshire town could be flooded.

Water is being pumped out of the 300-million-gallon Toddbrook Reservoir and an RAF helicopter is dropping 400 tonnes of aggregate around it.

Part of the dam wall collapsed on Thursday afternoon

My concern is how will 400 tonnes of ballast hold 300 million gallons of water!!!!

Better pictures and video here.

https://www.dailymail.co.uk/news/art...rvoir-dam.html

Last edited by nomorehelosforme; 2nd Aug 2019 at 12:04.
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Old 2nd Aug 2019, 13:12
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Originally Posted by nomorehelosforme View Post
My concern is how will 400 tonnes of ballast hold 300 million gallons of water!!!!
Much the same way a simple cork would plug a small hole regardless of the volume of water on the other side.
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Old 2nd Aug 2019, 13:45
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From what I read they dropped 400 tonnes of aggregate upstream of the dam to divert water from entering the reservoir and other watercourses.

Now they are reinforcing the dam wall.

When I was on Mark 2 Chinooks 15 years ago I lifted iso-containers and troops but didn't get to do anything like this!
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Old 2nd Aug 2019, 17:58
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This BBC page has a good 1 minute video clip of them postioining and dropping from short lines. I like the careful adjustment after each bag goes down. Also BBC second video.
Reporting that the dam level has been reduced by 2m, which is a heck of a lot.

Last edited by PAXboy; 2nd Aug 2019 at 18:21.
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Old 2nd Aug 2019, 21:47
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Reporting that the dam level has been reduced by 2m, which is a heck of a lot.
when you see the capability of the high volume pumps they use - and you can see a few of them in the news pictures, they are about half-iso sized boxes - then 2m is quite understandable.

Nomore helos - the weight of the water on one side needs to be balanced by the weight of the dam on the other, they have simply put more weight on the dam wall where it had previously lost integrity.
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Old 2nd Aug 2019, 22:14
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Having watched the video of the Chinook, one of those random questions just popped into mind.

Seeing it drop 6 individual bags of aggregate at a time, very carefully and precisely, would it be quicker and/or cheaper to do it with say 6 Jetrangers or 350s (other types are available!), going round and round in a circuit taking one bag each at a time? Iím thinking of the high speed commercial lifting operations that you see with Christmas trees/rocks for dry stone walls, that sort of thing.

I have no idea how much a Chinook or a Jetranger costs, how much those bags weigh or if they could even be lifted by such aircraft.

And definitely no criticism at all of the job the Chinny is doing, just idle meanderings of the mind while walking the dog.
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Old 2nd Aug 2019, 23:44
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One possibility of why the Chinook/s were used is they are:
  • Available immediately
  • Highy experienced crew
  • An excellent training exercise
  • Effectively (for the local water authority) free. We may expect the Govt not to chargeback for it as it would be very bad politics {at any time} to have a dam fail when the Chinook and it's crew were available.
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Old 3rd Aug 2019, 00:18
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Originally Posted by [email protected] View Post
when you see the capability of the high volume pumps they use - and you can see a few of them in the news pictures, they are about half-iso sized boxes - then 2m is quite understandable.

Nomore helos - the weight of the water on one side needs to be balanced by the weight of the dam on the other, they have simply put more weight on the dam wall where it had previously lost integrity.

Crab, I started looking at the mathematics of this and gave up! That aside, some good pictures and videos on the Daily Mail
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Old 3rd Aug 2019, 06:34
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IIRC the Jet Ranger (B206) can only undersling 1200 lbs, the 350 is probably similar. I understand the Chinook can carry 28,000 lbs. Each bag is, I believe circa 2,000 lbs.
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Old 3rd Aug 2019, 06:38
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The bags underneath the Chinook are at least I cubic metre each. A cubic metre of gravel weighs 1.92 tonnes, or 4862 lbs. for short.

Slightly more than the 3,200 lbs. Jetranger's maximum weight.
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Old 3rd Aug 2019, 06:57
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Originally Posted by nomorehelosforme View Post
Crab, I started looking at the mathematics of this and gave up! That aside, some good pictures and videos on the Daily Mail
Think in terms of pressure, not weight. The extent of the reservoir behind the dam wall doesn't affect the load on the wall at all; it could go back a hundred miles or it could be a narrow canal between two parallel dam walls, but the pressure at the surface of the dam depends only on the depth, and the force on the wall is the integral of pressure x area over the immersed surface.
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Old 3rd Aug 2019, 08:36
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Originally Posted by Training Risky View Post
From what I read they dropped 400 tonnes of aggregate upstream of the dam to divert water from entering the reservoir and other watercourses.

Now they are reinforcing the dam wall.

When I was on Mark 2 Chinooks 15 years ago I lifted iso-containers and troops but didn't get to do anything like this!
Nearly 19 years ago, we were doing very similar jobs with the Chinook. Remember, the answer is 2 Chinooks, what’s the question?

https://www.independent.co.uk/news/u...se-622283.html
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Old 3rd Aug 2019, 09:01
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Originally Posted by chinook240 View Post


Nearly 19 years ago, we were doing very similar jobs with the Chinook. Remember, the answer is 2 Chinooks, whatís the question?

https://www.independent.co.uk/news/u...se-622283.html
LOL The journalist that wrote the first 3 paragraphs must have copied them from a WW1 report!
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Old 3rd Aug 2019, 16:40
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That's not a hole, THIS is a hole.....





Photo by Dave G 240 OCU at play.
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Old 3rd Aug 2019, 23:10
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Originally Posted by chinook240 View Post


Nearly 19 years ago, we were doing very similar jobs with the Chinook. Remember, the answer is 2 Chinooks, whatís the question?

https://www.independent.co.uk/news/u...se-622283.html
Now that's a blast from the past. I was trying to drive from Linton to Shawbury with all my kit during that deluge. Thwarted at every turn and country road I tried to escape from. Never been back to North Yorks since!
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Old 4th Aug 2019, 10:39
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Plastic
AS 350 B3 will pick up a tonne ( 1000kg ) bag of ballast. It would be way quicker and cheaper than the RAF. To be fair RAF pilots are not really trained to do repeat lifting like this hours at a time. Would be better on a long line. Normal lift cycle for us would be 1nm a minute including hooking up the load and placing within a ft of the required location.
Last time I saw a quote for a Chinnok it was £ 20k an hour, As350 is around £ 1k an hour plus ground crew and pilot

We attended the fires last year in Derbyshire, we arrived within 6 hours of being called out, took the military over 2 days to turn up. So would suggest that a civilian operator would be more on call, with better equipment and much more experience
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Old 4th Aug 2019, 11:10
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Exactly how many aircraft can you provide?

One small bird is not going to out lift the Chinook in the long run unless the haul is very short and the hook up time for the Chinook is slow.

This lifting by the Chinook is not exactly precision lifting but something any reasonably capable pilot can accomplish.

The Longline pilot does it all by himself....while the Military Chinook crew uses a crew member and pilot working together to get the load into the correct position.

I feel you under state the ability of the RAF Chinook crews to do a days work.....though with all of the HSE requirements, planning, briefing, and related administrative hurtles....it would take them a while to actually get to work as compared to the civil operator.

You have a point about using long lines....but then the military (RAF and US Army for sure) do not embrace that technique as a normal role or operational skill.

The military always seems to have a longer lead time and shows up with far larger a support crew than does a comparable civilian operator....been there and did that on both sides of the equation.


Last edited by SASless; 4th Aug 2019 at 12:23.
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Old 4th Aug 2019, 12:12
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The time to call the military is all about red tape and paperwork. But, as I said, I strongly suspect that the real cost of this will not be passed on as it is a great training exercise. The politicians will also see it as PR. So the cost is, effectively, greatly reduced.

The Canal and River Trust estimated on Saturday that 105,000 cubic metres (23 million gallons) of water had been pumped out in 12 hours.An RAF Chinook helicopter put 400 tonnes of sandbags on the affected part of the dam on Friday - adding a further 70 on Saturday.
You can also see just how much they have lowered the level, remarkable. BBC

In one report about the residents who refuse to leave their homes prattle the classic "Health and Safety gone mad" It would be interesting to know what he would/will say if his house was swept away and his family with it ...
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Old 4th Aug 2019, 13:03
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“We attended the fires last year in Derbyshire, we arrived within 6 hours of being called out, took the military over 2 days to turn up.” I’m sure that has nothing to do with military response times, in fact I know it hasn’t, more to do with political decision making.

“RAF pilots not really trained to do repeat lifting” Really, not sure what special training there is for lifting one load followed by another, isn’t that what they’re doing right now. I’ve spent 8 hours a day doing exactly that in a Chinook.

PS. Could you do it safely in 1.5 k vis, 500’ and in 1 mulch, which I suspect was the challenge given the late start time and forecast weather?





Last edited by chinook240; 4th Aug 2019 at 14:39.
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Old 4th Aug 2019, 13:59
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There's some poor information being posted about what RAF helicopter pilots are trained, or not, to do with underslung loads..

Load lifting on a 100 foot strop certainly wasn't uncommon in my time - it was often an essential tool, such as when the army put loads next to tall trees, instead of out in the open, to avoid giving away their position.

Not trained for repeat load lifting...? I assume you have never seen an army Brigade lift.
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