Technical Talk

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Mike Bull
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Re: Technical Talk

Post by Mike Bull » Mon Mar 30, 2009 6:32 pm

Actually, referring back to Steve's last post there- we know enough about K7's dash panel now to be able to say that there was little way it could have 'shattered'- it was in fact one of the most substantial bits of tin in the whole hull!
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KW Mitchell
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Re: Technical Talk

Post by KW Mitchell » Tue Mar 31, 2009 11:17 am

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.
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Renegadenemo
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Re: Technical Talk

Post by Renegadenemo » Tue Mar 31, 2009 12:36 pm

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.
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Re: Technical Talk

Post by f1steveuk » Mon May 04, 2009 11:52 am

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.
Steve Holter, UK and France, and sometimes reality....................

KW Mitchell
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Re: Technical Talk

Post by KW Mitchell » Tue May 19, 2009 9:15 pm

Bill - when you recovered BB, were the lead weights attached inside the rear of the hull to enable planing in Nov' '66 still there?

If so can you estimate their total weight, and, where was their centre of mass in relation to the transom?

Thanks,
Keith

Baz
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Unwanted Lift?

Post by Baz » Sat Nov 07, 2009 12:08 pm

A thought has just struck me, has anyone ever considered the possiblity of a lift element being created by the spray deflector panels alongside the air intakes?
In the photo of BB alongside the jetty the presentation of the two panels to air flow can be seen, almost like the bow shape of a boat!! I'm not much of an aeronautical fella, but
there would be a higher pressure on the outer surfaces and low pressure on the inner surfaces, even more so with the suction from the turbine. surely this would create some lift,
only becoming critical above a certain speed, and when the downforce of the engine was removed, it would only need enough to present BB's underside to the air flow and that
would be it; just a thought!
Regards to All
Baz.

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Mike Bull
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Re: Unwanted Lift?

Post by Mike Bull » Sat Nov 07, 2009 7:00 pm

I guess in theory the deflectors were intended to run dead straight through the air, presenting only their material thickness to the airflow?
'I am not what is called a "civilized man", Professor. I have done with society for reasons that seem good to me.'

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Re: Unwanted Lift?

Post by f1steveuk » Sun Nov 08, 2009 3:20 pm

Plus the later additions of the horizontal elements were put there to break down aero lift and prevent spray ingestion, but Mike is dead right, ken's notes stress that "nothing other than the materials thickness should be visible to the frontal area". K7 (and indeed CN7) were both designed to be aerodymaically nuetral, obviously easier in theory, but neverthless, that was the plan!
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turbocox
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Re: A Picture paints a thousand words....

Post by turbocox » Mon Nov 09, 2009 12:51 pm

Not meaning to distract from this thread being called "looking back in time -Archive Bluebird PHOTOS"

Renegadenemo wrote:
Now here's a curve ball for you. The system wasn't gravity at all fed. Fuel was siphoned from the main tank into a swirl pot with its own boost pump and from there into a second, auxilliary tank in the bottom of the hull - again with a boost pump - then into the engine. Because all the breather plumbing was thin-wall steel pipe it's long gone so we can't be sure how it was set up.

Now I have been reading back on this thread, This part started me thinking (stupidly thinking, probbably utter rubbish) but it was something I have heard of elsewhere.

You say that the "BREATHERS" are "thin wall" Is at all possible that the "BREATHER" somewhere along its length/or AT the TANK could have been squashed, crushed,dented or blocked? during refit or under more demands on them with the fitment of the Orph.

I know that the tank is a hard tank, not like a modern collapseable racing fuel cell, but I think it could be possible that "IF" the "BREATHER" system was strangled or had collapsed due to the higher demands of the orph, you can create a vacuum in the tank, as the space where the fuel used to be (at the start of the run) is now a void, and "SHOULD" now have been replaced by air from outside the tank via the tank breather/breathers.
If it has a resitrction in the "BREATHER" or blocked, collapsed section, does this reach a point where the pump can't siphone any more fuel even if it has fuel in the tank, because the pull of the pump equates to the same pull of the vacume above the remaining fuel? ,
is the pump turning but not able to draw any fuel?


Any thoughts??
Sorry for the bad wording/explanation of this question But the wife understood what I meant :lol:


Feel free to shot me down in flames I probbably talking C*&$ :D

I'm not intending to blame anyone just tring another angle on the debate.
Last edited by turbocox on Tue Apr 06, 2010 11:34 pm, edited 3 times in total.
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rob565uk
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Re: Looking Back In Time- Archive Bluebird Photos

Post by rob565uk » Mon Nov 09, 2009 2:30 pm

I am fairly sure the whole fuel system and especially the additional swirl tank was added/modified as part of the conversion to Orpheus. I think the swirl tank and pump were actually added at Coniston in late 1966 by Bristol Siddeley Technicians who were called in to remedy loss of power (and/or provide facilities for running at >100% rated power for short periods). So I don't think any starvation/restriction was a legacy of the previous Beryl installation. However, your idea of a pipe being squashed, crushed, dented or blocked is both interesting and entirely possible - but, unfortunately, impossible to prove for the reasons Bill Smith has already expressed. As I understand from Bill's other posts elsewhere, as the old fuel pumps and components are overhauled in the near future, dismantling may reveal previously hidden evidence and shed further light reasons for any fuel starvation effects - which could prove very interesting.

Until we find otherwise, as far as I know the official explanation for any surging in jet thrust remains "bucketting" effects at the air intake ramps- i.e. at a critical speed, forced airflow into the intake exceeds the flow capacity of the duct carrying air to the turbine and air is spilled out of the intake in bursts, producing a sequence at the air intake of flow, spill, flow, spill, flow, spill etc - the frequency of the sequence depending on speed above the critical speed.

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