Technical Talk

[KW Mitchell]

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]

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.

[f1steveuk]

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!

[turbocox]

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

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


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

I'm not intending to blame anyone just tring another angle on the debate.

[rob565uk]

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.

[klingon]

Don't know if the shock waves seen under K7 at speed are anything to do with the engine surging-(looks like someone "skipping" a stone on water-or might just be pressure buildup under the hull at speed-any ideas?

[f1steveuk]

Anything under the hull, and to do with contact with the water, showing as interupted spray patterns, would be to do with the tramping, or sponson walking, although it's possible, but would require a great deal of acceleration and de-acceleration to show visably in the "rooster tail".

Now obviously I have stated my opinion in print, (and before anyone asks, no I still haven't managed to get the Bristol report back from the holder of my archive!), but I'm sticking with the intermitant fuel pressure loss, especially after the Orph' was tweaked to run at 110%.

[Renegadenemo]

He's not kidding either! I honestly believe the design engineers were having a crafty competition amongst themselves to see who could sneak the most complicated design for a set of washers, spacers and springs past the bosses at Lucas. Next they had a laugh at those hapless folks tasked with rebuilding these things by making sure that as many components as possible are stacked ahead of the spring waiting to fire out at the release of a circlip. And should you ever find yourself having to dismantle one of these, be warned, every spring has a separate seat too, many of which aren't mentioned if you have the wrong rebuild book as we do, and they're chamfered on one side and there's no way of telling which way up they go. They fall out when you roll the pump over and bugger off under the bench. Aarrrgh!

Bonkers? Definitely...

[huszarail]

Bill, that pump; MGBB series? 1004ish?

[Renegadenemo]

It's supposed to be a MGD but it's not, and the maker's plate is still crudded up though it's getting cleaner. Will let you know when I get to the bottom of it. Trouble is, it's well recorded that the Bristol Siddeley boys swapped out the pump when Donald was short of power, but they didn't record what they swapped it for. Will find out soon though.