LAND AND WATER 
February 17, 1916- 
lonfj run justify thoir, oxi<;toncc ;' cither, their range of' 
flight will lint be so great as hoped or their powers of 
thght will be sacrilired in some respect, or possibly they 
will be found structurally deficient. The best that can 
be hoped is that they will demonstrate that the factor 
of safety really necessary is less than has hitherto been 
regarded as essential. Or perhaps that there arc 
better methods of wing construction available than those 
at present adopted. Either of these eventualities, if tnie, 
would justify some increase in weight in accordance with 
the rule given above ; the size of machine at which the 
weight of wing structure is twice the constant load, will 
be greater if the factor of safety be lowered or if wing 
stnirture design in the matter of weight saving be found 
capable of improvement. 
As a numerical illustration two examples may be 
given, illustrating condition of maximum (relative) 
capacity : 
(i) Single-seat machine. Military load assumed 
r= 160 lbs. : 
Lb. Per cent. 
MiHtary Load .. . .. 160 8.0 
Wing Structure, etc. .. .. 320 16.0 
Petrol Capacity .. .. .. 520 26.0 
Fuselage complete with landing 
chassis and Power Installation . . 1,000 50.0 
Gross Total Weight 
2,000 
100. o 
(2) Two-seat machine. MiHtary load assumed == 320 lb. : 
Lb. 
320 
640 
640 
1,600 
3.200 
Per cent. 
10. o 
20.0 
20.0 
50.0 
100.0 
Military Load 
Wing Structure 
Petrol Capacity 
Fuselage, etc. 
Gross Total Weight 
Question of Resistance. 
We may now pass from the question of weight saving 
to the question of resistance. It is frequently stated, 
and it is to some extent true* that, in the matter of the 
coefficient of resistance, the big machine possesses some 
advantage. Evidently an increase in size only renders it 
possible to reduce the coefhcient of resistance, it is" up 
to " the designer to make the most of this possibility. 
Clearly, if it can be shown that in practice the exigencies 
of constructional art allow of a big machine being built 
with a less coefficient of resistance than a smaller machine, 
the range of flight will be increased proportionately, that 
is to say, the range of flight, for a given percentage of 
the total weight in petrol, is inversely as the coefficient 
of resistance. 
It is to-day well understood that the resistance of a 
flying machine may be treated as made up of two com- 
ponents — the aerodynamic resistance due to the flight 
organs proper and the direct or " head " resistance due to 
the body and its appendages. The large machine may 
imdoubtedly have somewhat lower relative resistance as 
due to its flight organs, that is to say, its aerodynamic 
resistance per unit weight is less ; but the extent to which 
the small machine is at a disadvantage from this cause 
is comparatively unimportant, it is not a serious handicap. 
The difference in the body or fuselage resistance is more 
considerable ; it is sometimes possible to design a large 
machine for the execution of any given duty with com- 
paratively little increase in the Juselage. 
If we could assume the resistance of the fuselage to 
be an invariable or constant — no matter what the size of 
the machine may be — it would be possible to make out a 
case for a very much larger machine and that based on the 
consideration of weight alone. If the military load be 
taken to be the same in any case (the problem being to 
specify for a given duty the machine of greatest flight 
range), the fuselage might be designed to vary but little 
with variations of size, but the same does not apply to 
the landing chassis and other sources of direct resistance, 
at the best the saving in the case of two machines whose 
weights are in the ratio 2 : i, does not amount to more 
than 10 per cent, of the total. The portion of the 
direct resistance which is due to the alighting gear, and 
in the case of the naval type or seaplane, due to the hull 
•James Forrest Lecture. Proe.Inst.C.E., C XCVIII., p. 388. 
or float, will inevitably increase the larger the machine, 
and so in respert of these the increase in size will be of 
little relief to the designer. 
In most of the designs which have at present been 
prepared or carried into execution, the relief which is 
theoretically to be obtained by a careful design of the 
fuselage has certainly not been realised to the f\ill, and it 
would almost seem as if the designers were not alis'e to its 
importance. Sometimes two or more engines have been 
fitted independently, external to the fuselage, and in such 
a case it is at least doubtful whether any saving; of resist- 
ance has been achie\-ed at all. ' ' 
The employment of more than one engine in an aero- 
plane instead of diminishing may seriously increase the 
risk of failure. Unless so powerful an installation is 
fitted that one engine alone (or two engines out of three) 
will fly an aeroplane, no increased reliability or advantage 
from the .subdivision of the power unit is secured. The 
usual reason for more than one engine being specified is 
that at present the aeronautical motor of three or four 
hundred horse-power is virtually non-existent in this 
country. Thus it is at present scarcely possible so to 
design as to take advantage of size in the one respect in 
which size may in some degree justify' itself. 
Military Future. ' 
In conclusion, it is manifest that the future — the 
military future — does not and cannot lie with the 
machine of great weight and dimensions. Even if the 
methods of aerofoil construction of the future permit ol 
the necessary factor of safety being obtained on half the 
weight so far found possible (which does not seem highlj 
probable) the machine of o^'cr two or three tons weight 
will remain the exception rather than the rule. 
It has already been pointed out that in exceptionaT 
cases large machines of special type may be needed foi 
the carrying of giant bombs or torpedoes, or perhaps 
for the transport of some heavy material unit such as a 
mountain or field gun either as a whole or in parts. Also 
the Naval aeroplane may in certain cases require to be 
built on a larger scale than would otherwise be necessary 
or desirable in order to permit of it being sufficiently 
seaworthy when afloat in bad weather. These special 
types however come outside the scope of the present 
articles, Each case requires to be considered or discussed 
on its individual merits. 
The full and complete theory of maximum range 
has not been dealt with as being too highly technical ; 
if some of the disturbing factors are taken into account 
it is possible to make out a case for machines somewhat 
larger, perhaps 20 per cent, larger or heavier than given ; 
on the other hand, the best size of machine will ordinarily 
be less than stated since the last few miles of range are 
only obtained at the expense of a disproportionate in- 
crease of total weight which means tonnage ill disposed 
and an undue expenditure of petrol in the performance 
of any given duty. 
The February number of the Asiatic Review is speciallj 
devoted to Russian writers and affairs, and is noteworthj 
for the inclusion of an article by Mmc. Olga NovikofY, in 
which the writer shows clearly tlie unity pervading Russians 
of all classes with regard to the war and the necessity for a 
successful issue. Those familiar with Mme. Novikoff and 
her work will see, from this article, the tremendous change 
that the war has wrought on Russia, and the way in which 
social and domestic problems have been shelved for the 
pursuit of the more vital issue. An article on German finance 
and the Caucasian campaign in the Review is of more than 
ordinary interest, and as a whole it may be said that the 
character of the Asiatic Review is more than maintained in 
this distinctively Russian number. 
A History of the Royal Welsh Fusiliers, by Howel Thoma; 
(T. Fisher Unwin, 3s. 6d. net) is a breezy little summary o; 
the doings of this famous regiment from the time of its 
formation up to the end of the South African war, and is, 
at the same time, an accurate liistorical record of the Roj'a' 
Welsh Fusiliers, for the author, himself evidently a Welshman, 
has been sufticicntly jealous of the honour of the regiment 
he describes to miss nothing, and to ensure that liis work 
shall be of unquestionable veracity. It. is worthy of note 
that lie has been but little concerned witii history' that does 
not directly affect his subject. The result is an admirablv 
concise volume, extremely intcrcstine in character 
J 
