Crash Analysis

[mtskull]

Having discussed this with my friendly Airbus boffin, he reckons that, if all you want to do is measure lift, at the speeds we are dealing with the scale model will behave pretty much the same as the full-size article; it is only when you also want to start examining boundary layer behaviour etc. that things like Reynolds numbers and the physical size of the airfoil really come into the equation.

If you want to replicate the effect at a lower speed, then there's nothing else for it but to increase the density of the air; then we're back into pressurised and/or cryogenic wind tunnels, unfortunately.

[Renegadenemo]

Interesting... If we get a chance we'll take the little spar out again at the weekend and see if we can develop a method of getting more accurate data from it. Most likely we'll build it a little nose too just for added accuracy.

[mtskull]

Interesting... If we get a chance we'll take the little spar out again at the weekend and see if we can develop a method of getting more accurate data from it. Most likely we'll build it a little nose too just for added accuracy.

You can probably get by just with end-plates; what is important is that you have something to replicate the effect of the sponsons and hull in preventing spanwise airflow.

This is fascinating stuff and It will be very interesting to know the results, especially how it behaves with varying angles of attack.

You have demonstrated pretty convincingly that damage to the spar fairing could have turned it from a more or less neutral shape into a lifting surface; extrapolate the effect up to the region of 300mph and I'm sure it gets really interesting!

A word of caution in drawing too many conclusions; although you can derive some information by looking at the aerodynamics of a section in isolation, as you are aware, to get a full picture you need to know how it works in conjunction with the whole, not forgetting that on the boat it was working in ground (or,to be precise, water) effect. Then there's compressibility rearing it's ugly head as you approach 300mph....

Fifth-scale wind tunnel model of the entire hull, anyone?

[thunderer]

Fifth-scale wind tunnel model of the entire hull, anyone?

If you read back a couple posts, I think I suggested that, although that was in reference to the tail fin...............

......... Is there no way to (ahemm, excuse me for the bad language that follows) "build an exact 1/5 scale replica" of BB to test the theory of the effects (or not) of the fin on the stability of the craft?

[Renegadenemo]

Fifth-scale wind tunnel model of the entire hull, anyone?

I've given the info we have so far to a couple of boffins to get a feel for the extent we'd need to test further. What I mean is that if we only need a nose then we'll only build a nose but if the underside is useful or if the rig would be better served by a weighted structure to mimic the rest of the hull or if we can approximate the effect of the water surface in some way... That sort of thing. I'm presenting at AAIB next month so I'll do a piece on the accident and see what they think. Now they are clever chaps and chapesses!

[Richie]

personally i reckon the whole craft with interchangeable front spars etc (for dinged ones and non dinged ones) then the model could be placed in the wind tunnel at varying wonderful angles....plus with some dry ice (or what ever they use) you will get a lovely visual of what the damaged spar was doing (or could have been doing) to the airflow and how it may have effected other airflows around the rest of the craft. i reckon we could fab up something respectable.... i have seen people make the honeycomb out of boxes of straws cut and glued... but i am sure you clever folks would work something better out thinking on the model front if we had a boffin who could CAD the external shape of K7 you could get two mok ups made out of resin CNC'd

no doubt about it though this stuff is interesting..

out of curiosity having not read the books yet...... had Donald done any testing on the Bluebird (via models) in her 66 67 config to actually see if the unit was capable of 300 ?

dare i say, if DMC reached 320 on the return run prior hitting his own wake/wash...my thoughts are could bluebird in her rebuilt config still pose a challenge to the current 317.6 speed record if she were to go at those paces again (and i am not saying that she should....but was wondering none the less) if so it just further shows how far ahead of the game us Brits were way back in 67 ! after all 1978 and 317.6 is the best the world can do....not much more than Donald really ?

[mtskull]

after all 1978 and 317.6 is the best the world can do....not much more than Donald really ?

Hmm. True enough of itself, but if you think of it in the context that if DMC was the first man to exceed 300mph on water, then John Cobb was the first man to exceed 200 and Sir Henry Segrave the first to exceed 100.... can you see where this is leading?
Ken Warby's record average speed may well be lower than DMC's peak speed, but it is average, not peak, speeds that win records; furthermore Mr Warby is still around to tell the tale.....

As for whether K7 could theoretically still challenge for outright honours, I'll not tread on Mr Smith's toes by attempting to answer that one!

[Richie]

totally agree with where your coming from. My humble and unskilled observations on historic water speed records suggests that (more in the early years) not much in the way of testing or structural testing was done, or perhaps not enough was known re jet propulsion it seems a case of "We will give it a try" if I am right then these guys were exceptionally brave.....crackers....but brave with it. I only came to this conclusion when reading about Mr Cobb's crash I could not believe what I was reading that Crusader was made from wood !



my point about the dates is technology moves along and i would have thought that over a decade later more could have been achieved.....perhaps we as humans in our current technological state have reached the ceiling for maximum speed on water. it is but a mere humble uneducated opinion though guys so please take it as nothing more.

[mtskull]

reading about Mr Cobb's crash I could not believe what I was reading that Crusader was made from wood !
my point about the dates is technology moves along and i would have thought that over a decade later more could have been achieved

I think you might be surprised at how much wood there is in "Spirit of Australia"

Probably the biggest obstacle to the record being raised is not the limits of technology but cost of accessing that technology. Men such as Donald Campbell and Ken Warby don't come along every minute, either.

That said, I'm quietly hopeful that before too long we will see Nigel Macknight and Quicksilver prove their doubters wrong....

[quicksilver-wsr]

That said, I'm quietly hopeful that before too long we will see Nigel Macknight and Quicksilver prove their doubters wrong....

Thanks for the positive words. Much appreciated.

The World Water Speed Record has definitely been stuck at some sort of glass ceiling for a long time now. My own theory as to "Why?" is that the time-honoured, long-established ways of doing it have reached their limit. That's my view.

The Quicksilver project has gone too far now to stop. There's too much invested in it, in terms of time, money, effort and sheer heart-and-soul energy from lots of folk, and I'm certainly not going to be the one to pull the plug and let all the people down that have helped to get us this far. I'm totally committed to it.

Our team has held together well. We are working hard to bring it all to fruition. Time alone will tell if we can keep it all rolling to the very end. It's a team effort, and as long as there is a team there is a chance - and I think a good chance.