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Tech Talk

Posted: Mon Dec 01, 2008 4:04 pm
by f1steveuk
Thought I should poke my nose in!! So let's get stuck in, about this copyright issue, no. sorry

These mysterious bulkheads, could they be the remains of the water tanks, fitted in order to adjust the trim when first built, but cut away in part as "NLR"?

Re: Welcome

Posted: Mon Dec 01, 2008 4:56 pm
by Renegadenemo
The bulkheads are all part of the structure but half of them rivet straight onto the frame tubes so they're a little pointless really. I read somewhere that they're to divide the boat into watertight sections but they're only six inches deep in the middle and there's an inch gap undreneath where the corrugated inner floors go so I'm not sure what they're about in many cases. There's evidence of the original trim tanks at the rear. It seems they were fixed to the frame tubes and now the holes are blanked with rivets.

Re: Welcome

Posted: Mon Dec 01, 2008 7:45 pm
by f1steveuk
Steady Mike, you'll be suggesting next K7 had a sister ship, and it was this that really sank for insurance purposes.....................

It does seem strange, because these bulkheads aren't going to lend torsional strength, so perhaps just there in case they needed to mount bits on, fuse boxes, relays, lead ingots............

Re: Welcome

Posted: Mon Dec 01, 2008 8:11 pm
by Renegadenemo
I have a letter somewhere from an engineer in Manchester that he wrote to DMC in 1966 to say that he knew how to make K7 do 400mph but he'd only reveal the secret if the boat had its name changed to 'Greenbird 400' Couldn't see that happening somehow.
And if there's a conspiracy to be had I want to know where the bloody instrument panel went! Never found a trace of it...

Re: Tech Talk

Posted: Tue Dec 02, 2008 11:01 pm
by StuartB
Hello Bill/Guys found the Forum and now feel obliged to Join in. Might be a bit of a random theory but could they be there to break any free surface water surging through the boat and upsetting the apple cart. Where you get "free surface" ie water able to slosh about freely over a large area be it length ways or abeam of a craft its a common practice especially with larger vessels to rig temporary "dwarf bulkheads" the idea being not to stop the water completely and certainly allow it to drain towards any pumps in place but to stop a sudden surge which of course would have serious impact on center of balance and center of buoyancy. Before anyone points out the blinding obvious there shouldnt be that much water in the bottom of the boat but allowing say two gallons (ingested as the boat breaks onto plane) slosh around the hull would result in twenty pounds of weight able to move around the hull as it pleases Not such a good idea when planing angle and safety margins have such a narrow window. Very Geeky but worth more than a passing thought??


Re: Tech Talk

Posted: Wed Dec 03, 2008 12:52 am
by Renegadenemo

that's a theory I'd never considered and the bulkheads would certainly work extremely well in that application as any free water would be able to move about the boat but only by bleeding through the corrugations beneath the bulkheads so the pumps would get it eventually without it being able to move fast enough to cause an upset. Hmmm - interesting...

Re: Tech Talk

Posted: Wed Dec 03, 2008 11:28 am
by f1steveuk
The baffle theory is the most likely, although I recall Ken saying that the amount of water that could get in was minimal, and was usually "shot out" as he put it, by the acceleration, but it would ba as well to stop even half a pint shooting down to the tail and building up there, although again it's unlikely K7 would take in much water whilst on plane and at speed??

I'd still drop a line to HMS Rosyth (spelling??) as Futcher's lot were desperate for a dive momento, and weren't allowed the steering wheel, so maybe they nabbed the dash?? Or, because of the impact, maybe it shattered and shot the instruments all over the place??

Re: Technical Talk

Posted: Tue Mar 31, 2009 11:17 am
by KW Mitchell
The more I read and learn of Ken Norris, the more he intrigues me. He is typical of that British engineer/designer of the period who had a feel for materials, math's, science and not a little flare. He designed with pencil and slide-rule. No PC or CAD those days - although by god he would have embraced them if they'd been available.

Examining K7, the photo's, diagrams, memorabilia - and now a hulk in reincarnation - one is given a window into the thoughts of this gifted man.

A man remarkably comfortable in his grasp of the theory but one, too, struggling to come to terms with the compromises of conceiving a record-breaker. Tough ground for us mere mortals - but one we can work through if we try.

Our recent debate on the fin, whenst esoteric or functional, is one such area. I am firmly in the latter camp, routed in the aerodynamics as KN most assuredly was. And we can see his mind working in the stages of development of a craft initially designed to achieve speeds in the low 200's to something which - in ideal conditions - could exceed that by some 50% or so.

As always, an aviation analogy - the Spitfire; basic design pre-WWII, weight 5000lb, 1000hp engine, top speed ~350mph. End of WWII, the same airframe, weight doubled (~10000lb), >2000hp and top speed 450mph. Good basic design stands development!

Now, quite remarkably, K7 shares with the Spitfire a common development theme -their fins were enlarged. In the latter it was the effect of adding the massive power and weight of the RR Griffon compared to the Merlin.

As for K7 - what? Not directly the Orpheus - but indirectly the higher speeds that it created and the increased 'weathercock' stability in the yawing plane which was required - but what was the precise cause?

It clicked for me examining - dare I say 'fondling' Ernie's model last weekend. Seeing things in 3D sometimes helps and for me it was those sponsons.

It is those that embody all Norris's flare and equally the struggle with the (sometimes) conflicting requirements of hydrodynamics and aerodynamics. Increased weight, speeds and their effects on planing and buoyancy required increases in size and volume and planing geometrics. And then the struggle with the aerodynamics - and here I have to say that I cannot envisage a more elegant solution than that embodied, flat inner surfaces, streamlined outer surfaces attempting to minimise aerofoil lift - which in this case is in the non-conventional sense i.e. sideways and in a direction away from the hull. Beautifully balanced on both sides to maintain tracking.

However, the problem - fundamental to tri-planers. Those sponsons are in front of the axis of rotation i.e. the CoG (Centre of Gravity) and they produce a large yawing couple tending to divert the boat from track when perturbations in the water below or, at high speed, the air above, occur.

A stabilising force is thus required and at speeds in excess of 200mph this requires some aerodynamic empennage - i.e. a tail to enhance the diminishing effects of the hydrodynamic surfaces, the water fins and rudder. In K7's case - and at the time it was being designed and evolving - that meant to Norris a fin. Firstly, an addition then a progressive enlargement, based on the stability requirements of the (final) craft.

Such arguments for me have a neatness and order which fits the man who, unlike some of you who were privileged to meet him and of whom I am unashamedly envious, gave us K7 and fought the battles of it's development in equal measure and fortitude to it's illustrious operator.

Re: Technical Talk

Posted: Tue Mar 31, 2009 12:36 pm
by Renegadenemo
I always thought those sponsons were a brilliant design and Ken once told me they were the only piece of the boat he designed then never had to look at again. I'd long wondered on what basis the curved outer faces were designed and eagerly awaited the drawings. That's when the trouble started because he must've designed them half a dozen times in different ways, some of which were obviously not pursued, others less obvious. So we didn't know exactly how they were built. Then a photograph appeared of them under construction that deviated again from what was drawn but the curved outer faces did eventually turn up with the legend, 'smooth curve' pencilled alongside what was obviously a smooth curve. It seems all he did was put a heap of work into the hydrodynamic shape beneath then let the upperwoks follow it.

Re: Technical Talk

Posted: Mon May 04, 2009 11:52 am
by f1steveuk
Ken (and Lew') were an inspiration to me. I first met Ken as a fourteen year old, and wasn't patronised, or talked down too. Ken was very adapt at working out the level of those he was talking to, and then happy to interact with people on "their level", and yet still helping them understand. Lew was a little more direct, but both men talked to you as equals, never as if they were "something special". Both men's thinking could be at times, on a completely different plane to those around them, and to see them firing ideas off each other was amazing. Yet once they explained what they had come up with to those that would put pencil to paper, they were more than happy to listen and adapt to others ideas as well. I went through the Norris Bros archive several times, and the wealth of designs was staggering. Lighters for Calibre, magnesium wheels for BRM, Archimedes screw cement pumps, inflatable buildings (the latter of which can be seen on nearly a daily basis). That Lew' and his men came up with the inertia reel seat belt as a "give away" shows the depth of thinking, although Lew used to say, "every time I pull a belt across me in a taxi, I think, 'that's another five quid in Royalties we're not getting!'" The wierd thing is, in recent years, just such a belt saved Ken's life! Neither man ever refused help to anybody, finally at their finanicial detrement, and were generous to a fault. I didn't know Lew that well, but I really miss Ken.