Source: hereI must have been asleep!
In my recent article about knock, I featured a picture of a Hawker Tempest, one of my favourite aeroplanes. Unfortunately, the version shown obviously has a radial engine, and was therefore, one of the Bristol-engined variants - my extracts at the end of the article related to the "other" engine.
The picture above shows a "proper" Tempest, fitted with the staggeringly complex Napier Sabre engine - the one that used the 150-octane fuel. For those who do not know about this, it was technically fascinating, but really a nightmare for anyone who had to do anything with it. It was a sleeve-valved, 24-cylinder, supercharged job, with the cylinders arranged in "H" formation - i.e. two flat-12s arranged one above the other. It was very powerful - I recall reading somewhere that Napier achieved 100 BHP per litre with a prototype, a staggering achievement in an aero-engine. The site (devoted to the Tempest) that provided the picture is here.
However, complexity has its price of course. It was said that during the Second World War, a horsepower from Napier cost the British taxpayer £3. A horsepower from Bristol cost £2, whilst a horsepower from Rolls-Royce cost just £1!
Napier (formerly a car manufacturer) was acquired by the English Electric Company in 1943; the final aircraft effort was even more outrageous: this was a cruciform ("X") engine; both supercharged and turbocharged, it produced over 4000hp, but jets had arrived so that, as they say, was that. Napier did have success later however with the fascinating "Deltic" engine, used in railway locomotives and also I think, in ships. A diesel, this was triangular in section as its name suggests. There were three crankshafts (one at each corner) and six (opposed) pistons per row. Think about it!
Meanwhile, following William's comment on the last article, I am looking into ignition modifications. If my searches are succesful I shall be back on the thorny "knock" problem.
A bientôt.
In my recent article about knock, I featured a picture of a Hawker Tempest, one of my favourite aeroplanes. Unfortunately, the version shown obviously has a radial engine, and was therefore, one of the Bristol-engined variants - my extracts at the end of the article related to the "other" engine.
The picture above shows a "proper" Tempest, fitted with the staggeringly complex Napier Sabre engine - the one that used the 150-octane fuel. For those who do not know about this, it was technically fascinating, but really a nightmare for anyone who had to do anything with it. It was a sleeve-valved, 24-cylinder, supercharged job, with the cylinders arranged in "H" formation - i.e. two flat-12s arranged one above the other. It was very powerful - I recall reading somewhere that Napier achieved 100 BHP per litre with a prototype, a staggering achievement in an aero-engine. The site (devoted to the Tempest) that provided the picture is here.
However, complexity has its price of course. It was said that during the Second World War, a horsepower from Napier cost the British taxpayer £3. A horsepower from Bristol cost £2, whilst a horsepower from Rolls-Royce cost just £1!
Napier (formerly a car manufacturer) was acquired by the English Electric Company in 1943; the final aircraft effort was even more outrageous: this was a cruciform ("X") engine; both supercharged and turbocharged, it produced over 4000hp, but jets had arrived so that, as they say, was that. Napier did have success later however with the fascinating "Deltic" engine, used in railway locomotives and also I think, in ships. A diesel, this was triangular in section as its name suggests. There were three crankshafts (one at each corner) and six (opposed) pistons per row. Think about it!
Meanwhile, following William's comment on the last article, I am looking into ignition modifications. If my searches are succesful I shall be back on the thorny "knock" problem.
A bientôt.
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