Hot air makes the wheels (and propellor) go round

As promised, here's the engine which runs on air. My colleague Malcolm Rowney built it a couple of years ago and shows it at model engineering displays around East Anglia. The engine is a Stirling engine, and I think it would be accurately described as an external combustion engine.


Don't ask me to explain how it works: I think you need to know about the theory of gases. Yes, probably only A-Level physics stuff, but I've forgotten most of it! The main components seem to be metal tubes suspended in the top of a wood burning stove; a couple of pistons mounted one above the other in one cylinder;


and an ingenious rhombic drive to convert the up-and-down movements of the pistons to rotary motion. The photo above is looking down onto the rhombic drive mounted directly above the cylinder. The engine is driving a water pump and a dynamo. The stove will burn anything, but is usually fired with scrap timber. You might just be able to make out another important feature, between the yellow chimney and the aluminium box housing the gears: a kettle.

Here's Malcolm on the Thames in a boat powered by a Stirling engine. Malcolm, I hope you don't mind me borrowing your picture.


Advantages of Stirling engines (as far as I can tell): quietness and high efficiency.

And here's Malcolm himself, demonstrating it on YouTube (not one of my films - apologies for the muzak):

Tesla's coil makes the sparks fly

As well as the stationary (but working) exhibits at the Forncett Industrial Steam Museum which we visited a couple of days ago, there were some other interesting things.


Someone - I wish I'd asked his name - brought along a collection of seriously shocking electrical machines, many of which he'd built himself. One of these home made devices was the spectacular Tesla coil, which produces telephone number voltages on the shiny sphere. 500,000V is enough to ionise the air between it and the earthed wire dangling two feet above it. The resulting lightning is straight out of Frankenstein's lab, and suitably crackling and fizzing.


His gadget gallery included a Wimshurst Machine, an example of which was used to make pupils' hair stand on end when demonstrated in physics lessons at my school; a Victorian electric shock machine "for nervous diseases"; a mirror galvanometer which will measure currents as small as .005µA (not much good for checking your boat's alternator output, then); and a Geissler tube rotator.


Still to come: the engine whose power source is a solid fuel stove. No steam is involved.

Engines worth getting steamed up about

Yesterday afternoon we went to Forncett Industrial Steam Museum in Norfolk. It's less than ten miles away and we'd not been before, not when it was open, anyway.


There are some stonkingly huge engines there, most of which were originally installed to pump water.


One thing which struck me was just how quiet steam engines are: rhythmic heavy clonks and gentle sighs of steam being about all that there is. Your other senses are, of course, involved: the smell of warm oil and, outside, that of burning wood; the wondrous sight of giant bits of metal running up and down, or round and round so smoothly; and the feel of the heat from the huge boiler. The steam was distributed to the working exhibits via insulated pipes.



It was a full time job keeping the fire fed with scrap timber.


And, no, I haven't forgotten the sense of taste. I had a delicious portion of home-made apple crumble and custard in the canteen!

Stephanie's Country Kitchen

This is one of the times when I could really do with knowing how to do the "crossing out" trick with words. The title would have been "Stephanie's Country Kitchen (crossed out) Cafe". Oh, and knowing how to put an acute accent on an "e" would be good, too.

Driving through Wrentham in Suffolk last Friday I stopped off at the above establishment for a bite to eat. What did I have? Full English breakfast, of course.


Sitting looking at the twee teapot collection in the window I spotted one I thought I'd share with you.


Not really my cup of tea.

Top Thirty, 2009 week 41

Here is the UK Waterways Site Ranking as it stood at 0930 on Sunday 4th October 2009.


1 Jim Shead's Waterways Information (=)

2 JustCanals.com - Forums (=)

3 Pennine Waterways (=)

4 Granny Buttons (=)

5 CanalPlanAC (=)

6 Retirement with No Problem (=)

7 Water Explorer (+1)

8 Canal Photos (+6)

9 UKCanals Network (-2)

10 Narrowboat Gypsy Rover (-1)

11 Jannock Website (=)

12 nb Epiphany (+1)

13 Towpath Treks (-3)

14 NBNorthernPride (-2)

15 Waterway Routes (=)

16 Narrowboat Bones (+1)

17 Derwent6 (+1)

18 nb Lucky Duck (-2)

19 nb Anonymous Two (+2)

20 nb Warrior (+3)

21 Narrowboat Debdale (-2)

22 Boating Holidays in the UK and Europe (-2)

23 Warwickshire Fly Boat Company (+1)

24 Takey Tezey Tales (-2)

25 Google Earth Canal Maps (-)

26 UK Waterways Ranking Site (+1)

27 Working Boat Hadar (-2)

28 Seyella's Journey (-)

29 Halfie (=)

30 The Meaning of Ubique (-4)

The figures in parentheses denote the number of places moved since the previous chart; (-) denotes new entry or re-entry; (=) denotes no change.

The number of entries remains at 82.

Hot news about Shadow

You remember the overheating problem we had on Shadow on our Easter cruise? Well, it's come back to bite us. I've just had a phone call from a fellow owner to say that the problem is much worse. He tells me the head gasket was replaced a few weeks ago, but the engine is still overheating. He's been running with the coolant filler cap removed,stopping every half hour, refilling the coolant, bleeding the skin tank, and carrying on. And he's been doing this for two weeks!


It seems that combustion gases are entering the cooling system and boiling away the water. Do we need a new engine?

Woodend Lock

There'll be more fresh canal stuff when we've done our next cruise, in not many weeks' time (hooray), but for now here's a picture of Bridge 53 at the tail of Woodend Lock on the Trent and Mersey, taken on our Easter cruise. What I want to know is, what are the niches in the bridge, either side of the arch, for?

BW request: Slow down to below 4 mph.

Received from British Waterways this morning:

Advice: Llangollen Canal‏
From: Editor, Waterscape.com (editor@waterscape.com)
Sent: 01 October 2009 09:54:24

Culvert 46 Llangollen Canal

Thursday 1 October 2009 - Friday 13 November 2009

Works are taking place to Culvert 46, Llangollen Canal. The works are located very near to the junction with the Prees Branch. There is no navigation restriction, however boaters are requested to proceed with extra caution and slow down to below 4mph (my italics) as contractor’s floating plant may be in the vicinity of the works.

Enquiries: 01606 723800


Slow down? Yes. To below 4 mph? Just how fast does BW think we actually go?
On Shadow, on a wide, deep canal such as the Grand Union, we do between 2.5 mph and 2.8 mph. That's the speed which the boat and we seem to be most comfortable with. We rarely find we're holding anyone up: if that's the case we let them pass (and usually catch up at the next lock).

Passing moored boats we slow down from this blistering speed to perhaps 1.5 mph to 2.0 mph, depending on the depth of water and distance from the boats. Should we encounter contractors' floating plant we take the same care.


bank protection works just north of Hatton Locks, Grand Union Canal, November 2008

The advice BW gives above merely has the effect of reinforcing the notion that the minimum speed limit on canals is 4 mph, and that you must go at this speed whenever possible.

It's like roads. In a 30, 40, or 50 mph speed limit, how fast do drivers go? Yes: 30 (and a little bit), 40 (and a little bit) or 50 (and a little bit). The limits are treated more like minimum speeds, not maximum.

Forget actual speeds, BW. Ask boaters to be aware of the delicate nature of canal banks; cruise such that they create no breaking wash; look after structures such as locks and bridges; and slow to tickover past moored boats and other obvious obstructions such as "floating plant".

After all, just how many boats are equipped with a GPS speedometer?