Dambusters: Building the Bouncing Bomb
Joined: Mar 2009
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From: SW England
Great watching that guy chucking that DC4 around - same age as me too!
Seriously, I wonder how that Prof got the funding to do (not quite) what Barnes Wallis did 68 years ago. Still, I'm glad he got it, very entertaining
Seriously, I wonder how that Prof got the funding to do (not quite) what Barnes Wallis did 68 years ago. Still, I'm glad he got it, very entertaining
Joined: Feb 2006
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From: Falling off the end of the thread
I detect something of a 'trouser moment' is beginning to stir...
Fascinating viewing...... The programme that is, not watching Beagle trying to get it up...........
Joined: Jul 2002
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From: N Yorkshire, UK
Back to the Program
In early part ( first 15 min) clips of 2 Post War test runs - first was 'hair raising' and second Disastrous
What type of a/c was performing test runs my guess is some form of A-26 Invader - which possibly indicates US involvement (in the Post War tests not the actual WWII mission)
PZU - Out of Africa (retired)
What type of a/c was performing test runs my guess is some form of A-26 Invader - which possibly indicates US involvement (in the Post War tests not the actual WWII mission)
PZU - Out of Africa (retired)
Joined: Sep 2007
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From: Somewhere Sunny
Umm, I think tests were initially conducted from a Wellington airframe. The aircraft remained in trials use well after the war. Before FI was 'invented', it was understood that the Wellington didn't fall apart as frequently as the 4 engined heavies. Of course, the geodesic airframe was also invented by Sir Barnes Wallis.
Perhaps Dr Hunt is the sort of chap, in an earlier life, would have invented similar weapons when the Realm was threatned. Garden shed, rusty nail, under-investmentand a hand-cranked generator and eh, voila! a war-winning weapon mortgaged to the US to get us out of more financial poo!
Perhaps Dr Hunt is the sort of chap, in an earlier life, would have invented similar weapons when the Realm was threatned. Garden shed, rusty nail, under-investmentand a hand-cranked generator and eh, voila! a war-winning weapon mortgaged to the US to get us out of more financial poo!
Joined: Oct 2002
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From: Surrey
Fascinating programme. I had read previously about the importance of the back-spin, in that the Magnus effect on the store as it sank would have generated a force that caused it to hug the wall of the dam so that the water-tamping would do the damage when it exploded. But I hadn't realised how important the backspin was for the bouncing performance.
I'll look at my recording again but I think the commentary defined the benefit of the back-spin then as the aerodynamic lift it generated on the store (again, Magnus effect) as it travelled through the air. I think there might be another reason. We all know that pebbles skip better on water the faster you throw them. Well, a back-spinning store hitting the water has a contact speed between the two that is much higher than the simple forward speed of the mine - it's that plus the perimeter spinning speed. So the bouncing dynamics are those of a store hitting the water at a higher speed, and hence it bounces better and longer. That, plus the angular momentum of the spinning store keeping it orientated correctly make the whole concept of 'Upkeep' a triple work of genius.
I'll get back to the pictures of Miss York now. Thank you BEagle.
I'll look at my recording again but I think the commentary defined the benefit of the back-spin then as the aerodynamic lift it generated on the store (again, Magnus effect) as it travelled through the air. I think there might be another reason. We all know that pebbles skip better on water the faster you throw them. Well, a back-spinning store hitting the water has a contact speed between the two that is much higher than the simple forward speed of the mine - it's that plus the perimeter spinning speed. So the bouncing dynamics are those of a store hitting the water at a higher speed, and hence it bounces better and longer. That, plus the angular momentum of the spinning store keeping it orientated correctly make the whole concept of 'Upkeep' a triple work of genius.
I'll get back to the pictures of Miss York now. Thank you BEagle.
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What type of a/c was performing test runs my guess is some form of A-26 Invader - which possibly indicates US involvement (in the Post War tests not the actual WWII mission)
Last edited by Trim Stab; 3rd May 2011 at 07:52.
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Well, a back-spinning store hitting the water has a contact speed between the two that is much higher than the simple forward speed of the mine - it's that plus the perimeter spinning speed.
The backspin gives the bomb a considerable rotational energy - when the bomb hits the water, part of this rotational energy is converted to kinetic energy in the upward bounce. This explains why on some of the videos the bombs were bouncing substantially higher than the aircraft that had dropped them.
The other part of the programme that they rather glossed over was the final drop with the "live" bomb. They implied that the explosives were contained in the bomb - but I very much doubt they were!
Joined: May 1999
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From: Quite near 'An aerodrome somewhere in England'
Looz'yana pork? What's that - hog jowls smothered in cayenne pepper relish to disguise the taste?
Call-me-Dave's put-down on PMQs was priceless - no doubt the rancorous nuLabor wimmin on the Opposition benches loved it....
I thought it was pretty clear - they merely removed the dummy bomb and placed the 'live' bomb (which had the same mass and physical properties) in the same impact location, then detonated it. Rather impressively! There was no suggestion that it had been flown under the DC-4.
Call-me-Dave's put-down on PMQs was priceless - no doubt the rancorous nuLabor wimmin on the Opposition benches loved it....
The other part of the programme that they rather glossed over was the final drop with the "live" bomb. They tried to imply that the explosives were contained in the bomb - but I very much doubt they were!
I don't own this space under my name. I should have leased it while I still could
Joined: Dec 2002
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From: Lincolnshire
The water spout from that explosion was interesting as it looked a bit like the Prince of Wales Feathers with both sides of the water plume turning back in on themselves.
It was actually not that different from the artificial plume in the Dambusters where they used a horizontal flow superimposed in the vertical. If they ever make the new film I hope they learn lessons from this one.
I didn't see a dog at the airfield though so it was not that realistic.
It was actually not that different from the artificial plume in the Dambusters where they used a horizontal flow superimposed in the vertical. If they ever make the new film I hope they learn lessons from this one.
I didn't see a dog at the airfield though so it was not that realistic.
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From: 58-33N. 00-18W. Peterborough UK
As our friends at Buffalo Airways are game for anything what else can we do? Here’s an idea. Find another DC4/6 and paint the pair as one 9 Squadron (I’ll provide the bats.) and one 617 Squadron. Then fit a couple of bomb sights. (See where I’m going with this?)
Next we need a Norwegian Fjord and an old freighter of around 50,000 tons. Drawings for Tallboy bombs are available at Hendon. Anything else we need to get started?
Next we need a Norwegian Fjord and an old freighter of around 50,000 tons. Drawings for Tallboy bombs are available at Hendon. Anything else we need to get started?
Joined: Dec 2008
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From: Over Will's mother's, and climbing
Interesting, too, to hear of "The Arch B*stard" - a moniker for Gibson I hadn't been aware of.
Can someone confirm that the post-Dams raid Highball bouncing bombs were nearer to being spherical than the Upkeep weapons?
Can someone confirm that the post-Dams raid Highball bouncing bombs were nearer to being spherical than the Upkeep weapons?
Joined: Dec 2006
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From: Whanganui, NZ
New Dambusters film
If they ever make the new film I hope they learn lessons from this one.
Just in case they haven't already got a copy, maybe you could drop Weta Digital (who will be doing the special effects) a line at [email protected]
Red On, Green On
Joined: May 2004
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From: Between the woods and the water
For those that missed it, it's not on 4OD, but is on the web as a torrent.
I thought that Dr Hunt's assistant should really have been in a period uniform, complete with correct hosiery. BEags would have liked that
I thought that Dr Hunt's assistant should really have been in a period uniform, complete with correct hosiery. BEags would have liked that
I don't own this space under my name. I should have leased it while I still could
Joined: Dec 2002
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From: Lincolnshire
One thing I didn't pick up from the programme was the problem they had with balance on the wartime bomb. As it was spun so the explosive had a tendency to unbalance the bomb.
Dr Hughs discovered the need for a balanced bomb but did not touch on the wartime problems.
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From: Baston
So what was the fuss regarding height judgement on board the a/c in these experiments? Over mirror-calm water, relying on an old boy's judgement? How often in his fire-fighting role does he fly very low over water? Why not create a lop with a few high speed boat runs? Surely there are simple laser surveying tools that could be used these days? When I buy/ sell a house, the agent no longer uses tape!
Or even a weighted dangling string, calibrated against the shore-based sticks and strings
or, or, or ........
But not seat of the pants stuff, totally out of order. Valuable a/c, valuable co., never mind the old boy's drinking buddies.
I'm glad that the pilot will never get to fly me; 0/10 marks for airmanship from this simple Metman, and I can see why the good Dr. stayed on shore.
Very good documentary nevertheless, actually good on the physics and good at my [educated but not physics] wife's level.
Or even a weighted dangling string, calibrated against the shore-based sticks and strings
or, or, or ........
But not seat of the pants stuff, totally out of order. Valuable a/c, valuable co., never mind the old boy's drinking buddies.
I'm glad that the pilot will never get to fly me; 0/10 marks for airmanship from this simple Metman, and I can see why the good Dr. stayed on shore.
Very good documentary nevertheless, actually good on the physics and good at my [educated but not physics] wife's level.