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296. Little Things

04/05/2017

While 1264 has been here at home, I’ve taken the opportunity to sort out a couple of things.

The socks (or are they gloves?) that protect the propeller in transit have done sterling service, but needed replacement. An offcut from the local carpet shop proved exactly the right size, and is now doing the job.

And I’m proud of myself for having come up with a way of filling the pulsometer which is supposed to tell us that the oil pump is working correctly.

Word from all the experts was that it has proved impossible, but I’ve come up with a way that takes only a couple of minutes, and doesn’t spill a drop of oil anywhere…

The pulsometer is the glass dome on the right of the picture. It’s connected to with a small bore oil line to a tee in the output from the oil pump, and the level should pulse in time with the strokes of the pump.

The difficulty is that the line is closed – it comes to an end in the glass dome, so it’s difficult to see to persuade the oil into it.

The solution? Undo the two bolts securing it to the panel and let it hang upside down, with the isolating cock open and the knurled nut holding the glass in place loosened.

Then disconnect the oil line into the engine and connect it using a piece of rubber hose to the primer pump (an oil can modified to allow us to prime the cylinders with petrol).

Fill the oil can with castor oil and pump until the pulsometer bulb is more than half full, then shut the cock, tighten the knurled nut, and re-attach the pulsometer to the panel. Simples!

It will be interesting to see how it works in practice. The manual says it’s possible to use it to check the speed of the engine by counting the number of pulses against a stopwatch, though I doubt anyone ever did this in flight, particularly as the pump is turning at 1.8 times crankshaft speed, so you need to be pretty good at mental arithmetic as well!

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From → Building, Technical

5 Comments
  1. Roger Green permalink

    It’s not at all relevant to your pulsometer (marvellous term) but the pic is so reminiscent of the way competitors turned up for the Military Aeroplane Competition at Larkhill in 1912. One of the requirements was to unpack the transporting case and assemble the aeroplane within a certain time. Something you might be up against at Larkhill on 7 July!

    • Actually, the Scout would have been well adapted for this element of the competition, had it been available a couple of years earlier. We can rig her ready for flight in 2 hours; for static display it takes about an hour.
      It was said that they could rig the Scouts in the hangar on the front of HMS Vindex in 10 minutes. It might be interesting to see if we could train up a team of modern RN personnel to achieve that…

  2. Tim Brown permalink

    Not a bad effort… Wilfred Parke and the Avro Type G team managed to assemble their machine fro the MAC in 1912 in just 14.5mins

  3. Tim Brown permalink

    I believe the ‘pulsometer’ on the Gnome was about the only instrument fitted to Boxkites… if one excludes the piece a wool, trailing behind the front elevator; and the brass swinging device used to measure airspeed by defection of the pointer by airflow through the wings?

    • Who needs instruments? We taught ourselves to fly hang gliders in the early 1970s with no instruments at all. Grandad’s recorded interviews say exactly that about the Boxkite. He did his first solo on one after 90 minutes’ instruction on a completely different type.

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