Technical Talk

[Richie]

or just let it purge without warning and watch them soil their jeans instead....by the end of the night i had twigged that when the pumps go on... ear defenders go on

[Renegadenemo]

I heard somewhere that when the system was first commissioned in 66 the crew were so terrified of it they made Bill Vanryn (the Lucas Rotax engineer in charge of making it work) stand next to it when it was first charged to see if he believed in it. He's a sprightly old guy of 90-something who I speak to regularly but I keep forgetting to ask if it's true.
Having spent many years around HP air in the diving world it still scares the crap out of me and, though we've had both of K7's bottles tested to 3500psi and imposed a max WP (working pressure) of 2000psi, I still creep around it as soon as the precision regulator tells me there's more then about 1000psi in there - not that creeping around would make the slightest difference if it went off with a bang.
The good thing about tonight's work is that we now know that 1500psi will blow the boat off the water never mind start her engine so we have another operable, original system. Just some fettling needed now to make it reliable in the field before we all get to stand by the lake shore and hear that evocative, fearsome blast of air that heralded Donald's runs all those years ago.

[speedboatstuart]

hI JUST READ THE DIARY ENTRY FOR AUGUST AND SAW MENTIONED THE 3" BY 1" DIA PIPE MOUNTED THROUGH THE OLD HINGE PLATE AT THE FRONT OF THE INTAKES ABOVE THE HEADREST WITH A COVER OVER IT . COULD THIS HAVE BEEN A WIRING CONDUIT FOR THE CAMERA POD THAT WAS AT ONE TIME FITTED IN THAT POSITION TO RECORD THE RUNS ON FILM. ?

[Dominic Owen]

hI JUST READ THE DIARY ENTRY FOR AUGUST AND SAW MENTIONED THE 3" BY 1" DIA PIPE MOUNTED THROUGH THE OLD HINGE PLATE AT THE FRONT OF THE INTAKES ABOVE THE HEADREST WITH A COVER OVER IT . COULD THIS HAVE BEEN A WIRING CONDUIT FOR THE CAMERA POD THAT WAS AT ONE TIME FITTED IN THAT POSITION TO RECORD THE RUNS ON FILM. ?

That was my first thought as well, especially with it being encircled by numerous rivet holes that don't seem to serve any purpose connected with either the hinge or intake cover. If that's the case, however, it seems strange that the cover should be a blister with the rear edge open.
The only antenna I can remember seeing in any pictures was a foot or so further back, although I do have an early shot from the rear that shows something sticking up near the front of the intake cover. The perspective is a killer though and the resolution isn't good enough to zoom in on it.

[Dominic Owen]

I've just been going through a load of pictures and have a theory.

In the cockpit.jpg

I can't tell if this is from before or after the camera pod was fitted (I'll leave it to one of the anoraks to count the wrinkles on Don's face to work out the exact date! ) but in the top left there is what appears to be a small camera unceremoniously bolted to the intake skin. What isn't visible in the above shot is that the wire comes out of the back of the camera, loops round and disappears into the back of that little blister;

camera.JPG

If I were a gambling man, I'd wager that the tube was nothing more than a wiring conduit and was retained with that particular cover over the top just in case they ever wanted to stick another camera up there.

[sheppane]

... And this is the view you get from said camera. K7 rolling to starboard at Canandaigua in the summer of 57. The image of DMC in the cockpit was taken at Coniston in November 57.
The Black item in the foreground is the cockpit canopy release. The item in the top left, probably a dead fly.

Camera View Canandaigua 57 small.jpg

[Mike Bull]

It's interpreting and reinstating these little details that makes K7 so fascinating to work on sometimes!

In the sequence of three pictures in the diary, you see the tube sticking up, then with the hinge plate over it, then the D-shaped cover on top of the outer skin; here is an in-between shot from the other side before the D cover went on which shows the hinge plate in place, the outer skin over the top, and a little doubler piece which is an exact reproduction of the original which was too crusty to use again-

P9086917a.jpg

See the larger hole beside the tube? This could just as easily have been used to pass a wire through, though why you'd do so instead of using the tube itself is a mystery.

This certainly wasn't the only route wires could take from inside the plenum to the outside, either- about a foot behind this vent, roughly under where the radio aerial mounted, there is a four inch square hole through the top of the inlet duct- in comparison with the little tube you could pass anything you liked through that!

Personally I think that the tube was originally intended to be a small opening to vent the plenum chamber to the outside, but that it ended up being used to run wires through and so on for convenience.

Lastly for 'speedboatstuart'- please don't post in all-capital letters, in netiquette it's highly frowned upon and is considered to be 'shouting'. Cheers!

[DamienB]

... And this is the view you get from said camera.

Panto time - "Oh no it isn't!"

That little box isn't a camera - see first attached pic. And note how the cable doesn't appear to go into the fairing in question after all, but appears to dive straight through the skinning just aft of it. If it was a camera (which it clearly isn't), seeing as it's offset to starboard, the canopy handle would be offset to port in the shot.

k7-box.jpg

I think that's the view from the camera that was housed in the large centerline blister behind the cockpit (see second attached pic) - on that the lens was offset to port within the fairing, which matches up nicely with the canopy handle being offset to starboard in that shot. However I thought this camera went on in 1958 around the same time the sponsons were enlarged?

k7-camera-pod.jpg

The fairing in question isn't evident in photos pre-1957, is covered entirely by the 1958 camera, but returns after that and was there in the final config. Is it actually on the centerline Mike, or offset to port?

[Renegadenemo]

Personally I think that the tube was originally intended to be a small opening to vent the plenum chamber to the outside, but that it ended up being used to run wires through and so on for convenience.

I remember seeing a pic somewhere of the headrest missing and a big box of gubbins in the plenum that I took to be the early radio equipment. It would make sense to put it there because it was dead space and I'd imagine 1950s radio gear to be bulkier than the later set fitted in the cockpit in 66. I'd imagine also that it would get hot and a little vent up there would allow some of the heat to escape. Just a theory.
And wow! to the new cockpit shot... at long last we now know that the start system arming light was red. We think it was green when it was first fitted but that his nibs wasn't having any of that and it was swapped for a red one.

[Mike Bull]

Is it actually on the centerline Mike, or offset to port?

The D shaped fairing/cover is indeed on the centreline, or at least, it's on one of the boat's many differing centrelines!
A quick browse through Leo's Big Book Of Donald shows that it first appeared in 1956.