The Last run....

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sheppane
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Re: The Last run....

Post by sheppane »

I think this shows K7 coming off plane, with the bow causing the fwd thrown spray as it settles back in the water. The publication of Book of Racing Campbell's in 1960... some 6 years before the transom water brake was fitted....

It's a brake of sorts, but only applicable when K7 runs out of fwd momentum as a true hydroplane and flops back into the water of her own accord...
Here are a couple of pics from Dec 66
vlcsnap-118734.jpg
vlcsnap-118657.jpg


[quote="polo"]I found this photo in 'the racing campbells' by richard hough. It shows BB using the water brake
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Last edited by sheppane on Sun Apr 04, 2010 3:46 pm, edited 3 times in total.
'When you go down into the arena, you know that sometimes, you're likely to get your nose punched. You do it with your eyes open. You take the risks'

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polo
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Re: The Last run....

Post by polo »

My apologies, it appears that you are correct. I've just checked the book again.
Oh its a first edition and its signed by Gina!! I didn't know that!

lsrdatabase

Re: The Last run....

Post by lsrdatabase »

polo wrote:I found this photo in 'the racing campbells' by richard hough. It shows BB using the water brake
bb waterbrake on.jpg
I've scaned from my books, they may be a bit clearer. Hope they help.

Regards, Fred

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Renegadenemo
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Re: The Last run....

Post by Renegadenemo »

I may be wrong here but I think that transcript is actually archive material from 67 that ken had to work with and for that reason it wouldn't do to mess with it. Of course it's wrong, in all probablility it will always be reported wrong, much as there'll always be someone out there believeing that the BBP began with a conspiracy by the BBC and that the HLF were right all along so we'll just have to report it more accurately when we write our memoirs and hope it sticks.
I met an old boy in Coniston recently who told me that often when K7 was accelerating or slowing during the 66/67 campaign she'd occasionally demonstrate a condition where water thrown over her bow made her look like she was encapsulated in a huge bubble. Now that I'd like to see.
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sheppane
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Re: The Last run....

Post by sheppane »

Mike, am I that predictable? ;)

6 more pictures showing K7 coming down off plane. The first three are from the planing condition, the last 3 show K7 in her taxiing condition with the nose still up before finally dropping down totally. The initial deceleration from planing produces the most violent spray, and the 'bubble' appearance...
K7 Off plane.jpg
K7 Bubble.jpg
K7 Spray.jpg
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'When you go down into the arena, you know that sometimes, you're likely to get your nose punched. You do it with your eyes open. You take the risks'

Donald Campbell, Bluebird and The Final Record Attempt. https://www.facebook.com/bluebirdk7/

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sheppane
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Re: The Last run....

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Slowing down from the taxiing position...
K7 Slowing .jpg
K7 Slowing 2 .jpg
K7 Slowing3 .jpg
I think that illustrates the point pretty well... talk about anorak overkill! :ugeek:
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'When you go down into the arena, you know that sometimes, you're likely to get your nose punched. You do it with your eyes open. You take the risks'

Donald Campbell, Bluebird and The Final Record Attempt. https://www.facebook.com/bluebirdk7/

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mtskull
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Re: The Last run....

Post by mtskull »

Going back to the statement re. the snapped forward engine mounting, whilst accepting that you have ascertained for certain that it broke in tension, can you be 100% sure that this couldn't have happened during the accident? -I would have thought that, given the manner in which the aft part of Bluebird cartwheeled across the water, it would have been unlikely to have placed the mounting under a constant compression load; more likely a series of load reversals which would have weakened the mounting until the final failure took place in tension.

I am sure that this has all previously been considered, but for the benefit of the ininitiated (i.e. me) please could somebody describe Bluebird's engine mountings, in particular, where did the forward mounting anchor to the hull, where were the gimbals positioned relative to the point of balance of the engine, and was the jetpipe rigid enough to stop the engine rocking about once it had squashed the rubber baffle and was bearing against the hull itself?
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Re: The Last run....

Post by Renegadenemo »

The engine is mounted on a pair of trunnions forward of the hot end and the engine's CofG. They carry the weight of the engine and transmit the thrust. The front mount, as I've called it, isn't really a mount at all. It's only a turnbuckle for aligning the engine duting installation but in K7's case it was left in a permanent state of tension because the jetpipe and hot end of the engine wasn't supported as it is in the aircraft installation and its natural tendency is to drop without the turnbuckle. It takes a good heave to lift it too. The rubber water baffle is only 3mm thick and would have offered no resistance to the jetpipe dropping in the event of the turnbuckle failing. The failed mount was tested by the AAIB metalurgy dept and found to be machined from a 40 tons-tensile billet and, as best they could determine because of corrosion to the fracture face, the failure was a low-cycle fatigue failure meaning it worked gradually until it snapped and wasn't pulled apart in a single, violent action. There is a possibility that the mount failed during the crash sequence but this is only really credible if it was about to fail due to fatigue anyway. It's also worth thinking about the frequency and shock loading a water surface could deliver compared to an aircraft in flight.
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mtskull
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Re: The Last run....

Post by mtskull »

Wow, that was quick!

-Thanks Bill, that is all fascinating stuff, and food for thought.
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Re: The Last run....

Post by Renegadenemo »

I've always stopped short of suggesting the engine mount failure is the definitive cause of the accident because there's no way to positively determine whether the mount was on its last legs and the crash finished it off or whether it went first but I was taught back in my student days to 'always go with the hypothesis that uses the least number of assumptions' and the broken engine mount represents a single failure that can explain the entire accident.
Broken turnbuckle, loss of gyroscopic damping in pitch, fluctuating thrust-line angle, boat on limits at some 80mph beyond its maximum design speed, I've got the bows out... I'm going! ugh...
But there is another equally possible scenario, apart from a simple blowover, bottling it and lifting off the throttle at very high speeds or hitting the reflected wash from the first run by going ridiculously fast when closer than normal to the eastern shore.
One of the battery posts was burned through. Now did this occur after the cockpit was severed and its wiring bundle along with it or did the electrical system finally object to the recently bodged-in second fuel boost pump that was added shortly before the fatal run and the loads this placed upon it once the engine hit full song?
If you believe the broken engine mount theory you then have to reconcile this to there being no sign of thrust from the engine as its jetpipe was pointed at the lake surface from only a very short distance away while Donald said nothing about a failure he'd have had to sense and react to by getting off the throttle several seconds before the meeting of jetpipe and water surface.
Had the electrical system failed all Donald would've seen was a flash from the LP boost warning lamp, the pressure gauge was mounted on the side of the boat where he had no way of seeing it, and the engine would have spooled down uncommandedly as the engine-driven piston pump cavitated causing a loss of thrust and the aerodynamic centre of pressure to move aft along the underside rather quickly.
Donald's commentary on both runs was in real-time and as comprehensive as his command of the craft. The unexpected nature of the accident added to the lack of thrust has always suggested to me that something failed in the propulsion machinery and caught him completely off guard at a crucial moment. Let's see what it takes to get an Orph' running again within that hull and on all the original systems and we'll see what we can learn, eh?
I'm only a plumber from Cannock...

"As to reward, my profession is its own reward;" Sherlock Holmes.

'Sometimes you gotta be an S.O.B if you wanna make a dream reality' Mark Knopfler

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