Pic of the Day

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Renegadenemo
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Re: Pic of the Day

Post by Renegadenemo » Sun Jun 24, 2018 11:23 am

Did you have a spare canopy made while you were at it?
There's two parts to the canopy, the actual surface and the frame it sits in. we have a spare surface and that's all trimmed in but we don't have a complete spare frame yet. The frame comprises the rear section that fits into the angle surrounding the headrest, two lower rails that slide in the cockpit rails and the curved section at the front lower edge onto which that little roller fixes. We don't have a spare curved piece, though we do have a chunk of material to make it from. It's doubtful we'll have time to make a second canopy before we go to Scotland but we'll take all the bits so we can cobble one together should the need arise.
I'm only a plumber from Cannock...

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

I have wrought my simple plan
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Or the man who’s half a boy.

Sir Arthur Conan Doyle.

rich1608
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Re: Pic of the Day

Post by rich1608 » Sun Jun 24, 2018 2:36 pm

My views on the air start. If it were down to me I would either forget about using the onboard system and stick with off-board air permanently as is happening on Bute, or have two new spheres made from scratch. As you said Bill no-one knows how many cycles the originals have been through and no amount of testing, x-rays etc.. can confirm this. I know this breaks the originality rule but these components are safety-critical and for ultimate peace of mind I think it would be best to have new ones made if the onboard system is going to be used. Is this a possibility that has been considered?

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Engine 711
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Re: Pic of the Day

Post by Engine 711 » Sun Jun 24, 2018 6:27 pm

Mike Bull wrote:
Fri Jun 22, 2018 6:46 pm
Renegadenemo wrote:
Fri Jun 22, 2018 6:11 pm
But for Bute we are simply going to plug in our offboard supply and hit the go-button.
...and seeing as Pic of the Day is pretty much accounted for for a while, here's the off-board connection in progress- we're utilising the existing opening in the side of the boat that used to be for the electric start, with a new plate- all totally reversible.

01.jpg
Very neat - like it.... ;)

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Engine 711
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Re: Pic of the Day

Post by Engine 711 » Sun Jun 24, 2018 6:54 pm

Renegadenemo wrote:
Fri Jun 22, 2018 6:11 pm
The bottles have to be tested and they are - they were brand new in 2016, as were all the delivery hoses, fittings, gauges, etc.

The onboard air system I reckon is, and always was, good for no more than three starts. You can't use the last 700psi anyway because it simply will not accelerate the engine to start speeds. The bottles were previously rated to a working pressure of 3200psi with their life limited to 400-odd cycles, but we have no way of knowing how many cycles had been completed by the time we came along. A cycle was deemed to be any event that dropped the bottles below 2000psi from full. So, having carried out all kinds of hot-work on them, we tested to 3200psi and imposed a new WP of 2000psi
Unfortunately this just isn't enough for a clean start with the LP starter. Interestingly, we saw similar gas consumption figures in terms of pressure drop in the storage cylinders to those seen in 66 at Haywards Heath but we were using 100litres of storage and they had 32 - 16 per sphere - so the HP starter seemed notably more gas-efficient. That said, the log from Norris Bro's also shows that they kept stopping to charge the bottles so they weren't going to ever get six starts from them either. They also sailed close to the wind with the JPT and had to shut down on one occasion because the temps went out of limits.
So next we snaffled a HP starter from a museum engine but no way was it going onto the 101 Orph' - the gearbox is totally different on the front of the engine, so instead we set about discovering the difference, which turned out to be a plate ahead of the start turbine with a series of converging nozzles such that compressed air impinges directly onto the turbine blades. It's far less wasteful so with just such a plate made up and tested we saw our gas consumption halved to achieve start speed (1000rpm approx) Now we were getting somewhere but much development work is still needed.
We need more NDT on the bottles and another test as they've been used a bit since. If all is well we may test to a higher pressure and give ourselves a higher WP but only if this is agreed by those who know in the world of pressure vessels and materials. We also need to get some hard data on what the hybrid LP/HP starter is doing with its air to see what we realistically have to do to make the system work. Even if we could safely life it for maybe 30 starts that would see us through a proper proving trial. But for Bute we are simply going to plug in our offboard supply and hit the go-button.
@Renegadenemo - Thats for that info. All starting to make sense.... Starting.... :D

The 400 cycles limit makes some sense, as the system came from an Experimental Aircraft, which probably wasn't expected to do very much. For K7 as rebuilt in 66, it also made sense, being enough for one more record - and nothing more. For K7 now, I can see its a concern - and the uncertain capacity makes it worse still.

High JPT means the fuel went in too soon, relative to the compressor speed - basically crank or motoring speed was too low.

The LP vs HP starter differences make a lot of sense. The actual rotor could be the same - with the HP version just having a set of nozzles to drop the inlet pressure down.

The idea, from @rich1608, of getting a new set of spheres is interesting - but at what cost.....? New ones could be designed for a much longer life - and to current pressure vessel rules - but would almost certainly be heavier.... :( Perhaps not a go-er.....

At least Bute should give some more hard data on air consumption, which should allow a way forward.

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Renegadenemo
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Re: Pic of the Day

Post by Renegadenemo » Mon Jun 25, 2018 1:28 am

The 400 cycles limit makes some sense, as the system came from an Experimental Aircraft, which probably wasn't expected to do very much. For K7 as rebuilt in 66, it also made sense, being enough for one more record - and nothing more. For K7 now, I can see its a concern - and the uncertain capacity makes it worse still.
The spherical bottles were made by Bristol Aerojet, who mostly made rocket components, so I suspect this is what they were designed for originally and we're likely a single-use component, hence the life measured in cycles for the aircraft application. The bottles were bought in for the Lucas Rotax start system that was later evolved into the rapid start kit for the V-Bomber force with components - we would discover later - totally interchangeable from the Vulcan to the old Hunting 126 system.
High JPT means the fuel went in too soon, relative to the compressor speed - basically crank or motoring speed was too low.
Exactly - they got out of the starter as soon as they dared, so what does that suggest? If there'd been plenty of gas to spare why not stay in until the engine is accelerating happily with a bit of starter assistance and keep the JPT in limits.
The LP vs HP starter differences make a lot of sense. The actual rotor could be the same - with the HP version just having a set of nozzles to drop the inlet pressure down.
The turbine disc has two more blades on the HP variant and a slightly larger diameter but the gear ratios through a double epicyclic kit in both cases brings it all back to the same thing. The nozzles make the available gas do as much work as possible compared to the LP version that just has a set of guide vanes to throw the mass of LP air in the right direction. It can afford to be wasteful and inefficient and therefore much less stressed.
The idea, from @rich1608, of getting a new set of spheres is interesting - but at what cost.....? New ones could be designed for a much longer life - and to current pressure vessel rules - but would almost certainly be heavier.... :( Perhaps not a go-er.....
I think we're in a safe zone with 2000psi WP and a limited life but making the system work for one good start depends on achieving sufficient efficiency within the starter. That's the target and I think it's achievable. We may have to make a start with the offboard gas to get a good heat-soak into the engine and fluids then shut down and decant into the onboard system then go for a start close to the JPT limits.
At least Bute should give some more hard data on air consumption, which should allow a way forward.
We have 300 starts worth of data that includes gas consumption, which is why I think we can get the old system to do the job but what we've never had is the hyd pump in the mix on startup and we also now have the dry-break connector for the offboard air, which introduces its own losses so there's still lots to learn. Exciting times ahead!
I'm only a plumber from Cannock...

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

I have wrought my simple plan
If I give one hour of joy
To the boy who’s half a man,
Or the man who’s half a boy.

Sir Arthur Conan Doyle.

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Engine 711
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Re: Pic of the Day

Post by Engine 711 » Mon Jun 25, 2018 9:34 am

@renegadenemo - Thanks - all good answers....!

A further idea for the Starter would be to just have a simple orifice, to restrict flow & drop the pressure, in the Starter inlet (or before it) - instead of the plate - the idea being to drop the pressure to around 40psi, at the inlet to the Starter turbine. No idea what the size should be - but it could be very simple & either gradually opened out, or make several to try, of different sizes.

Agree completely, re the Hot Starts - says they were not so well off for air, as they should have been. But again, they were not planning on doing much further running. Same at the 110% rating - fine for just a couple of runs - get the record - and go to the Boat Show. But it was not to be.

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Engine 711
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Re: Technical Talk

Post by Engine 711 » Mon Jun 25, 2018 9:36 am

Well Done all. The new 'trailer' looks fab.... :D

2018-06-25.JPG
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Black Knight
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Re: Pic of the Day

Post by Black Knight » Mon Jun 25, 2018 12:10 pm

That canopy really completes the look. Awesomeness :o

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Richie
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Re: Pic of the Day

Post by Richie » Mon Jun 25, 2018 12:22 pm

Folks, you really have no idea, the images do this thing zero justice (referring to the boat and the cradle)

she is a monster to behold !
Clarence come out ov zat tank at vonz !

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Mike Bull
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Re: Pic of the Day

Post by Mike Bull » Mon Jun 25, 2018 12:25 pm

Hopefully lots of folk will come and do some beholding on the shores of Loch Fad. 8-)
'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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