Immediately
upon our return to Dayton, we wrote to a number
of automobile and motor builders, stating the
purpose for which we desired a motor, and asking
whether they could furnish one that would develop
eight-brake horse power, with a weight complete
not exceeding 200 pounds. Most of the companies
answered that they were too busy with their regular
business to undertake the building of such a motor
for us; but one company replied that they had
motors rated at 8 h.p. according to the French
system of ratings, which weighed only 135 pounds,
and that if we thought this motor would develop
enough power for our purpose, they would be glad
to sell us one. After an examination of the particulars
of this motor, from which we learned that it had
but a single cylinder of 4 inch bore and 5 inch
stroke, we were afraid that it was much overrated.
Unless the motor would develop a full 8 brake
horse power, it would be useless for our purpose.
Finally
we decided to undertake the building of the motor
ourselves. We estimated that we could make one
of four cylinders with 4 inch bore and 4 inch
stroke, weighing not over two hundred pounds,
including all accessories. Our only experience
up to that time in the building of gasoline motors
had been in the construction of an air-cooled
motor, 5 inch bore and 7 inch stroke, which was
used to run the machinery of our small workshop.
To be certain that four cylinders of the size
we had adopted (4" x 4") would develop the necessary
8 horse power, we first fitted them into a temporary
frame of simple and cheap construction. In just
six weeks from the time the design was started,
we had the motor on the block testing its power.
The ability to do this so quickly was largely
due to the enthusiastic and efficient services
of Mr. C.E. Taylor, who did all the machine work
in our shop for the first as well as the succeeding
experimental machines. There was no provision
for lubricating either cylinders or bearings while
this motor was running. For that reason it was
not possible to run it more than a minute or two
at a time. In these short tests the motor developed
about nine horse power. We were then satisfied
that, with proper lubrication and better adjustments,
a little more power could be expected. The completion
of the motor according to drawing was, therefore,
proceeded with at once.
While
Mr. Taylor was engaged with this work, Wilbur
and I were busy in completing the design of the
machine itself. The preliminary tests of the motor
having convinced us that more than 8 horse power
would be secured, we felt free to add enough weight
to build a more substantial machine than we had
originally contemplated.
Our
tables of air pressures and our experience in
flying with the 1902 glider enabled us, we thought,
to calculate exactly the thrust necessary to sustain
the machine in flight. But to design a propeller
that would give this thrust with the power we
had a t our command, was a matter we had not as
yet seriously considered. No data on air propellers
was available, but we had always understood that
it was not a difficult matter to secure an efficiency
of 50% with marine propellers. All that would
be necessar y would be to learn the theory of
the operation of marine propellers from books
on marine engineer ing, and then substitute air
pressures for water pressures. Accordingly we
secured several such books from the Dayton Public
Library. Much to our surprise, all the formulae
on propellers contained in these books were of
an empirical nature. There was no way of adapting
them to calculations of aerial propellers. As
we could afford neither the time nor expense of
a long series of experiments to find by trial
a propeller suitable for our machine, we decided
to rely more on theory than was the practice with
marine engineers.
Read
the full article: How
We Made The First Flight
The
flights of the 1902 glider had demonstrated the
efficiency of our system for maintaining equilibrium,
and also the accuracy of the laboratory work upon
which the design of the glider was based. We then
felt that we were prepared to calculate in advance
the performance of machines with a degree of accuracy
that had never been possible with the data and tables
possessed by our predecessors. Before leaving camp
in 1902 we were already at work on the general design
of a new machine which we proposed to propel with
a motor.
