Evening star., 1922-07-02

| type. he said, would be equipped with
F, engines OF immense power. in order 10
! furnish sufficient air pressure, and when
! driven to a sufficient altitude, the Vanes
would be SO adjusted that horizontal
motion would result The plane could
then fly in the usual manner, hnaiiy
! using the vanes again to descend YER
; tically.
Other Type Onered Army.
! The other type offered to the Army,
! he said. was of the present wing plan.
! equipped with three propellers, two
placed far out toward the wing ends
and with vertical rudders and atlerons
similar to those in use. The quicker
lifting power was to be gained by
I having the wash of the central pro-
peller act upon elevators on the tan
| of the body. while the side propeliers
would wash against the special aiie-
: rons on the wing tips
! When in the air, DR.. Zahm con-
! tinued. this machine could maneuYer
as does the ordinary plane. cut figures
and do stunts" besides being able to
! rest motionless in any desired posi-
| tion-vertical with nose up. If need
! be.
! The best feature. he said. is that
! both planes of the new types are en-,
i tirely feasible and can be constructed
! at any time. In fact. several Euro
! pean inventors and manufacturers are
patenting designs of the second type
; notably the Frenchman Bleriot, one
j of the pioneers of aviation.
! Experts for the government. studied
| the second type during the war. it
/; was explained, but the matter went
no farther.
/. The general drawbacks of their
construction. DIR. Zahm said. were.
! first. the great cost: second. the in
creased weight of the machines as
! compared with present engine EN-
| cheney. and, third. the need of de-
| veloping motors with greater power
! and less weight per horse power and
! with a greater amount OF depenaa,,
bility AS il is. he said. successful
/ helicopter may be flown to any helght,
! but the operators will never know
when the engine will give cough
and die away.
! Disadvantage Overbalnnced.
! The German experimenters. how
i ever he added. have in part overbal-
anced this disadvantage. 1t has been
determined by experiment that pro-
| peller of three or four narrow blades,
| caused to revolve by the air pressure
resulting from a forced descent with
| a dead engine. will develop as much
parachute resistance as solid DISK
of the diameter of the blade spread
In addition. the German machine -
/ equipped with air cushions on tne
! landing bottom so that the landing II
| forced. may be made comparatively
| easy.
| Means of steering experimental
| helicopters. and of which one would
undoubtedly be used in successful
| machine. are two. The first is
| means of fitting the propeller shait
! or the whole machine. when IT VIII
| travel in that direction; the second
! being the use of vanes similar to
i those already described. With the
/ latter. Dr. Zahm thinks. helicopter
! sufficiently powered should be as able
| to cut caIers in the air as aviators do
; at present
| Any of the types advanced would
| in warfare be of great use in bomb
dropping or for observation. The
| main disadvantage. that OF being
good target for artillery fire while
stationary could be Offset by quick
ness of movement from point to point
ard short stops while lowering.
! Still, DR. Zahm points out in sum
! ming up. the fact that the war De-
partment was offered such machines
at time when all resources were
| being expended in better or more
! efficient implements OF warfare and
! rejected them. although they are
| completely feasible. is sufficient indl-
| cation of their war value. AS TO
/ their being put to commercial or So
| cial uses, the immense expense pre-
J cludes the possibility.