Side Valve Engines
The Crusader
Louis' thoughts turned to aero engines. In the autumn of
1912, he designed a V8 engine which could deliver 120h.p. at 2,500 r.p.m. It
was called the Crusader and was widely announced in the British aviation
press, in March 1913. This was welcomed by the British aircraft
manufacturers as no really suitable British engines were available at the
time.
|
From 'The Engineer', 11th
April, 1913.
An English-Built Aviation Engine
Many of our readers are acquainted with the wonderful
work which has been done lately by what we may call tiny
engines in driving motor cars at enormous speeds. Among
these may be mentioned the performance of the Sunbeam car,
which won the Grand Prix Race on the Continent last year
with an engine which had four cylinders of only 80 mm. bore
by 150 mm. stroke. The successful results obtained with this
engine on a car have led the Sunbeam Company to embody the
main features in an 8-cylinder "V" type aviation engine,
which we illustrate below.
This "V" form of construction leads to very great saving
in weight, the crankshaft and crankcase being reduced in
length, while the crank webs are also reduced and the valve
gear is simplified, so that this particular engine, which
gives 150 brake horsepower at 2,500 revolutions per minute,
only weighs, with its carburettor, 425lb., or less than 3
lb. per horsepower.
This alone is not however, sufficient to make it a
suitable aviation engine, as the weight to be taken into
consideration is that of the complete motor with fuel, etc.
for a trip of a reasonable number of hours' duration, and it
is here even more particularly that the Sunbeam engine
proves its claim to rank as a very fine aviation engine. The
consumption as taken under normal flying conditions works
out to only 0.49 pints of petrol per brake horsepower per
hour, so that fuel economy has received an equal amount of
attention with efficiency and saving of weight.
As will be seen, each pair of cylinders lies in the same
plane, so that only two cams are required for four valves of
each pair of cylinders, while both connecting rods drive the
same crank pin. The cylinders have copper water jackets to
save weight, and the big bell-mouth to allow the long stroke
connecting rods to clear, is an interesting feature of the
design, which otherwise differs very little from ordinary
motor car practice, though the water cooling of the valve
pockets should be noticed.
The camshaft is cut out of the solid with all its cams,
and its big diameter bearings and is another instance of the
way in which every ounce of superfluous metal is dispensed
with. The revolution speed of 2,500 per minute is of course,
too high for the best propeller efficiency, and this is
reduced by half by a 2 to 1 gear embodied in the crank case.
Altogether this little engine, as we must call it, is a
remarkable piece of work, and we should like to congratulate
the designer, Mr. L. Coatalen. on the success which be has
already attained.
|
|
The Crusader's first flying test should have taken place on
6th August 1913, after one of the engines was fitted to a Radley-England
Waterplane. It never actually managed to take-off, because of problems with
the design of its two hulls. After this tragedy, the Sunbeam Motor Car
Company decided to purchase an aircraft to test the new engine. It was a
French Farman biplane, and Sunbeam decided to hire a full-time test pilot
for the project. This was John Alcock who later became well known for his
famous non-stop Atlantic flight with Arthur Brown. The test flights began in
the middle of October 1913, and took place at Brooklands. There were initial
teething troubles, but these were soon overcome, and in December the
aircraft began a long period of intensive flight tests which ranged over
most of southern England, and continued until the outbreak of War in 1914.
The War Office became interested in the engine and one was
purchased by the Royal Aircraft Factory. It was delivered to Farnborough for
extensive bench testing and delivered a maximum of 135h.p. There were one or
two problems to be sorted out, but if they could be resolved the engine
looked as though it would be suitable for military use. Some Crusaders were
also fitted to power-boats that were built by Brookes, for the Smith's
Financial Group.
In March a Crusader was exhibited at the Aero Show in
Olympia. The bore had been increased from 80mm to 90mm and the engine could
now deliver 150h.p.at 2,000r.p.m. The engine had two side valves per
cylinder, was water-cooled, weighed 480lb dry, had two Claudel-Hobson
carburettors, and two Bosch magnetos. At the show, Avro ordered one of the
engines for the 510 seaplane, which was to be entered in the Circuit of
Britain Race. The race was cancelled due to the outbreak of War and
Crusaders were in demand for a very different sort of use.
The first military aircraft fitted with the engine was a
Royal Aircraft Factory RE.5 biplane, in July 1914. The engine was soon
fitted to many other aircraft:
Aircraft Fitted with Crusaders
| Aircraft Make and Type |
Number of
Engines Ordered |
| Maurice Farman 2 seater biplane |
1 |
| Royal Aircraft Factory RE.5 biplane |
1 |
| Avro 510 seaplane |
6 |
| Sopwith 806 Gunbus |
36 |
| Short 827 seaplane |
107 |
| Handley Page Type O biplane |
2 |
| Blackburn GP seaplane |
2 |
| Sopwith biplane bomber |
2 |
| Avro 519 bomber |
2 |
| Avro 527 reconnaissance biplane |
1 |
| Curtiss H-4 biplane |
1 |
| Curtis R-2 biplane |
14 |
| Coastal non-rigid airship |
50 |
| Sikorsky I1'ya Mouromet biplane |
30 |
The 110h.p. Sunbeam
This was the early version of the Crusader, before the bore
was increased to 90mm. It was always considered to be a separate engine by
Sunbeam, and a number were sold as such.
Aircraft Fitted with the engine
| Aircraft Make and Type |
Number of
Engines Ordered |
| Radley-England Waterplane No.2 |
1 |
| Maurice Farman 2 seater biplane |
1 |
| Sopwith 806 Gunbus biplane |
18 |
| Short 827 seaplane |
6 |
The engine was also fitted to the Sunbeam
24h.p. hill climb car of 1913. Two engines were supplied for use in the
Tollier powerboat of 1913, and another was used in the Brookes powerboat of
1914.
 |
|
 |
|
 |
Return to
Sunbeam |
|
Return to the
Aircraft Section |
|
Proceed to
the Mohawk |
|
