rexresearch.com
Airplanes # 3
Grooves Reduce Aircraft Drag
Langley Research Center, Hampton, VA
Aerodynamic drag can be reduced by may small longitudinal grooves machined in the aircraft skin. Experiments show that grooves parallel to the airflow reduce drag by 4 to 7 percent. The reduced drag translates into reduced engine power required to overcome the drag and ultimately to lower fuel consumption.
The grooves confine incipient bursts of turbulence so that they cannot expand and disrupt the boundary layer surrounding a moving craft. Most are V-shaped, but they may take a variety of dimensions (see figure). For example, they may have rounded or sharp peaks and symmetrical or asymmetrical cross sections. Asymmetrical grooves of various cross-sectional geometries may be arranged in some regular sequences to optimize the aerodynamic performance.
The most effective dimensions for reducing drag are indicated in the figure. The dimensions for reducing drag are indicated in the figure. The dimsnetions are small in comparison with those tested in previous experiments. In terms of law-of-the-wall (turbulent flow) coordinates, the heights are less than 30 and the spacings are less than 40.
This work was done by Michael J. Walsh of Langley Research Center.
USP # 4,706,910
Combined Riblet and Lebu Drag Reduction
System
(11-17-1987)
WALSH, Michael, et al.
Classification: - international: B64C21/10; B64C21/00;
(IPC1-7): B64C21/10;- European: B64C21/10
Abstract --- The invention is a system of flow control devices
which result in reduced skin friction on aerodynamic and
hydrodynamic surfaces. The devices cause a breakup of
large-scale disturbances in the boundary layer of the flow
field. Referring to FIGS. 1 and 2, the riblet device 10 acts to
reduce disturbances near the boundary layer wall by the use of
longitudinal striations forming vee-shaped grooves. These
grooves are dimensional on the order of the wall vortices and
turbulent burst dimensions 31 depicted in FIG. 3. The large-eddy
breakup device 41, depicted in FIGS. 4 and 5, is a small strip
or airfoil which is suspended in the upper region of the
boundary layer. Various physical mechanisms cause a disruption
of the large-scale vortices. The combination of the devices of
this invention result in a substantial reduction in skin
friction drag.
Scientific American (7 Feb. 1920)
Collapsible Wings for Airplanes -- Why Not?
There is no doubt that the bird is a better machine than any that man has made for the purpose of flying, at least so far. The moment a bird lands its wings are contracted, thereby enabling the bird to settle quietly on land or sea. It would be impossible for the bird to shoot straight down and alight on the chosen spot, were it compelled to do so with its wings fully extended. Yet it is for that very reason that our powerful flying amchines so often meet with accidents when landing. In addition to this, the present ever-rigid wing causes great inconvenience in connection with the housing with the housing problem and makes transportation very difficult.
If a gull should attempt to remain floating with wings stretched out on the sea, it would soon lose its balance and share the fate of the hydroplanes which in the recent attempt to cross the ocean had their wings badly battered when compelled to descend and alight on the rough sea.
We know that wings swinging back on hinges will reduce the original span of the plane to some extent, and partially solve this problem. It has remained for someone to design a practical and properly constructed practical wing for present-day types of airplanes.
A New York inventor, John Arthur Weis, has recently come forward with an ingenious contractable airplane wing, for which he claims ample strength, reliability and convenience. In fact, a British manufacturer has begun construction on a machine with this type of contractable wing. In order to produce a wing that may be folded automatically and almost instantaneously, this inventor has replaced the usual rigid spars with a collapsible construction, similar to the well-known lazy tong telephone holer but provided with suitable stop locks. In extending the wing fully the links of the lazy tong construction lie parallel to each other and are prevented from moving in the opposite direction by the aforementioned stop locks. At this point the lazy tong action ceases, and the construction becomes rigid. Since there are no folds or pockets in the airfoil or wing surfaces, each section of the wing can be covered independently with fabric or sheet aluminum. Provisions are made for having the airfoils airtight, despite the many sectons.
All important and vital members, such as distance bars, ribs, struts, stabilizers, and so on, remain intact and undisturbed. When the spars are brought into a straight line, the ailerons are in position to work on hinges just like those of any present rigid standard types, according to the inventor. The pilot can expand or contract the wings by means of a crank or lever in the cockpit. If desirable, a very simple device in the form of a little ratchet drum, worm-driven, in conenction with a handwheel and dial, enables the pilot to apply the necessary tension to the interplane bracings as soon as the wings are fully extended and locked.
According to the invnetor, the span of 60-foot machine can be reduced by the contraction of the wings to about 8 feet. The extra weight on a two-seater 110-horsepower biplane is about 100 pounds, consequently the loss in velocity is hardly more than 2 or 3 percent. When the wings are fully contracted the outlines of the machine resemble somewhat those of a grasshopper. All in all, the construction is most ingenious, but one must hesitate to pass on the practicality of this construction until it has undergone actual application to full-sized planes.
US Patent # 1,392,669
Expansible and Contrable Structure
US Patent # 1,427,669
Airplane
Vicompte de Rouge
Stabilizer
Popular Science (April 1934)
"Vanes On Mast Keep Glider Level"
Successful in its first test flights, a glider with an unconventional stabilizing device has been introduced by a French inventor. The stabilizer, carried on a mast above the wing, is used to correct any tendency to pitch forward or sideslip in flight. Its two hinged vanes are so wired that they may be folded flat or spread sideways by a control in the hands of the pilot, and thus stabilize the plane.
Popular Science (May 1932)
"Something New For Flying"
Below, Vicomte de Rouge, a French engineer and inventor, seated in his strange tailless plane. Opening the hexagonal control on the mast directs the plane upward and closing it guides it down. The rudders on the wing tips are used to steer the queer craft.
French Patent # 42286E
US Patent # 1,919,831
Stabilizing Device for Airplanes
