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A splendid technical success was
announced at the aerial pageant held i
in Rome in June, for the Diesel type
aero engine. On the morning of the j pageant a Fiat aeroplane fitted with ¡ a Deisel engine left the Fiat flying1 . ground in Corso Francia. Turin.- the . start being witnessed by several of
: the firm's directors and engineers, j
This was the first. Italian aeroplane propelled by a crude oil engine, this kind of engine having been first studied and experimented with in Italy by the Fiat Co.
The aeroplane arrived in Rome at the I/ittorio airport at 2.42 p.m. The pilot was Renato Donati, who is well known as the holder of several world's records. He was accompanied by the mechanic Cappannini. This excep tional machine, with its erude oil en gine, then flew over the Littorio field during the air pageant.
This marks a great step forward iu the application of the crude oil eu gine.
Both the daily and the technical press had already announced that the Fiat, was conducting very successful experiments in this field, and the news of this successful flight naturally captured at once the interest of the experts who rightly see in the use bf crude oil a great practical advance in aerial navigation.
As is well known, crude oil has three great advantages over petrol: It is non-explosive, non-inflammable, and costs about five times less than petrol, and therefore permits of the construction of engines of ' greater thermal efficiency, that is, - with a lower spécule fuel consumption.
Consequently, for aviation, the trude oil engine offers these advantages over the petrol engine:
(1.) Greater constructional sim
pUcity ; there are no carburetters^ or ignition apparatus (magnetos and sparking plugs), the pumps and in jectors that take their place being simpler and more positive m action.
(2.) Improved thermal efficiency, and therefore a lower fuel consump tion per h.p. hour and consequently a greater radius of action.
(3.) The use of a cheaper fuel. (4.) No risk of fire.
These advantages are sufficient to make the crude oil engine especially suited for commercial air lines and there can be no doubt that the future of transoceanic aerial communication is bound up with the development of this type of engine, the advent of which In Italy undoubtedly marks a memorable date in the history of Italian aviation.
In order to have a'n engine of this type available in the shortest possible rime for trials, not only on the bench, but also iu actual flight, the Fiat, in stead of building a single cylinder experimental eugine, preferred to take an existing aero engine ' of known characteristics, and convert it iuto a direct injection Diesel engine. An "A.12 bis" eugine was choseu for this experiment. *
The "A.N.L" engine is identical in general outline and overall dimensions with the "A.12 bis" type from which it is derived by means of the altera tions above mentioned.
It has six cylinders in line with a bore of 140 nun. and a stroke of 180
mm. It is water cooled aud the only auxiliaries necessary to its working
are the fuel pumps, lubricating pumps and water circulating pump. There are no carburetters, which are re placed by the aforementioned fuel pumps: neither are there auy mag netos, the ignition of the explosive mixture taking place automatically j through the high temperature of the
i compressed air. at the momeut of in- :
Í jection of the fuel into the cylinder.
'? The crankcase, oil sump, crankshaft,
-lubricating and cooling systems and!
their fittings do not differ from those
ordinarily employed in the usual j types of aero engines. The outstand- ¡
iug features of the new tyne of eugine j
are, the cylinders, pistous, valve gear. ¡
fuel pump and fuel atomizer.
Cylinders.-These are of the usual steel sleeve type, with valve chambers and water jacket welded on. They are proportioned to the higher pres sures they have to withstand, and in their heads have seats for two inlet and two outlet valves, whilst in the centre is the seating for the "fuel ! atomizer.
Pistons.-Of aluminium and of specially designed shape to form a good combustion space.
Valve Gear.-The inlet and exhaust valves are actuated directly off two parallel camshafts, according to the [ system used in the latest types of aero engines. The inlet valves com municate directly with the atmosphere and draw in air only, and not an ex plosive mixture as is the case with petrol engines.
The fuel is injected into the cylin- <
ders through the atomizer just when j
the piston has nearly finished its j
upward stroke, compressing the air . previously drawn in. The atomizer ;
opens automatically through the pres- j
sure of the fuel which it injects into ; the cylinder in a very finely divided . state, so as to facilitate its rapid.: ignition and complete and efficient ;
Fuel Pumps.-There are six fuel ;
pumps operated by cams and divided \ into two groups of three. They are
instruments of great precision, as ¡ they have to send into each cylinder j
the minute quality of fuel required i according to the load on the engine, j and under extremely high pressure, as
much as 200 or 300 atmospheres, j Provision is made for regulating the j quantity of fuel delivered by the ! pumps and also the length of the in- ] jection period; there is also am ar- j rangement for Varying the timing of .
the injection. j
Control of the engine in flight is . therefore obtained solely through the :
fuel pumps. j
Starting.-The engine is started by ' compressed air, through automatic j
valves on the cylinders and a distri- j
butor in the same way as with petro1, j engines. !
Actual Working Data.
Results of Tests.-In the length
bench tests to which it was subjected, ' the engine gave the following results:
Normal output, ISO hip. Normal speed, 1600 revs, per min. Maximum output, 220 h.p. Maximum speed, 1700 revs! per min.
At the maximum power output, the mean effective pressure (M.E.P.) is 100 lbs. per square inch, remarkably high even for the usual slow running: tyj>e of Diesel engine.
This eugine works with crude oil such as is normally used for four stroke Diesel engines, density 0.80. The consumption of fuel under normal load is about .42 lbs. per h.p.''hour, and remains practically constant at
both higher and lower loads. I
The aeroplane had to wait for maur years for the petrol motor, but .the ' pioneers of a quarter of a century and more ago were probing the se crets of the air in gliders.
Now. with the knowledge gained iu the air with power-driven aero planes, men are again turning their attention to gliders, and all over Britain gliding clubs are being form «d. GUdiug, in fact is likely to be u very popular summer pastime.
Wonderful flights of several hours' duration have been made in these engineles.s aeroplanes by taking ad vantage of favorable wind currents
! jver billy country, and .now an offer
.»f £1000 has been made to the pilot .if the first. all-British glider to cross
?he English Channel. To accomplish such a flight it. viii probably be necessary to attain a great height on favorable air currents over land, and tlieu turu seawards, taking advantage i.«f the steady breeze to maintain height or prevent a too rapid descent.
lt is quite possible that, when we üave become more familiar with air conditions, glider flights between de Quite places will be the rule. Mean while in América a flying-man has towed a glider behind his aeroplane across the continent, making the journey according to a previously ar ranged schedule in eight days.
Shall ? we have in future aerial rugs with strugs of barges in tow winging their way from continent to continent with the world's com merce?