This is the on-line portion of the bibliography of an article titled "A Brief Overview Of The History And Technology Of Junkers Flaps"  published in the September 2003 issue of the TWITT newsletter.  
 

European Patent Offices:

Here are some German patent numbers that may be interesting to those members who can read German:
396,621 (The Junkers "doppelflugel" patent)
516,082
516,083
643,682
647,894

U.S. patent office:

The Hugo Junkers home page

BOK-5 *  **  ***
Buro Osobikh Konstruktsii OKB merged into Sukhoi OKB in 1940

Kalinin K-12  *  ** 

The flying wings of  Michael Schönherr  * 

B.I. Cheranovskiy   *  **  ***
 
Lippisch Delta IV The slots are visible in the photograph but the 3-view shows a different airfoil than that shown in the A. R. Weyl article.  This is not a Junkers flap, it was included just to show some other types of external airfoil flaps that have been tried.  The  Park bench ailerons * were included for the same reason.

Tandem AirBike with Junkers flaps

Tom Speer designs foils for sailboats.  He also designed a wing with an external airfoil flap for an ultralight airplane.

The Condor Keel is an effort to design a multi-element sailboat keel. 

The 3-view drawings of the "BOK-5" and "Manxi III" that I reproduced for the article can be found in "Tailless Tale" by Dr. Ing. Ferdinando Gale'. 




Aerodynamic characteristics of wings with cambered external airfoil flaps, including lateral control, with a full-span flap

Platt, Robert C
NACA Report 541
1936
 

      The results of a wind-tunnel investigation of the NACA 23012, the NACA 23021, and the Clark Y airfoils, each equipped with a cambered external-airfoil flap, are presented in this report. The purpose of the research was to determine the relative merit of the various airfoils in combination with the cambered flap and to investigate the use of the flap as a combined lateral-control and high-lift device.

An Adobe Acrobat (PDF) file of the entire report (1,290,051 bytes):


Aerodynamic characteristics of NACA 23012 and 23021 airfoils with 20-percent-chord external-airfoil flaps of NACA 23012 section

Platt, Robert C Abbott, Ira H
NACA Report 573
1937
 

      Report presents the results of an investigation of the general aerodynamic characteristics of the NACA 23012 and 23021 airfoils, each equipped with a 0.20c external flap of NACA 23012 section. The tests were made in the NACA 7 by 10-foot and variable-density wind tunnels and covered a range of Reynolds numbers that included values corresponding to those for landing conditions of a wide range of   airplanes. Besides a determination of the variation of lift and drag characteristics with position of the flap relative to the main airfoil, complete aerodynamic characteristics of the airfoil-flap combination with a flap hinge axis selected to give small hinge moments were  measured in the two tunnels. Some measurements of air loads on the flap itself in the presence of the wing were made in the 7 by 10-foot wind tunnel.

An Adobe Acrobat (PDF) file of the entire report (1,548,461 bytes):




Wind-tunnel investigation of wings with ordinary ailerons and full-span external-airfoil flaps

Platt, Robert C Shortal, Joseph A
NACA Report 603
1937
 

      Report presents an investigation carried out in the NACA 7- by 10-foot wind tunnel of an NACA 23012 airfoil equipped, first, with a full-span NACA 23012 external-airfoil flap having a chord 0.20 of the main airfoil chord and with a full-span aileron with a chord 0.12 of the main airfoil chord on the trailing edge of the main airfoil and equipped second, with a 0.30-chord full-span NACA 23012 external-airfoil flap and a 0.13-chord full-span aileron. The results are arranged in three groups, the first two of which deal with the airfoil characteristics of the two airfoil-flap combinations and with the internal-control characteristics of the airfoil-flap-aileron combinations. The third group of tests deals with several means for balancing ailerons mounted on a special large-chord NACA 23012 external-airfoil flap. The tests included an ordinary aileron, a curtained-nose balance, a frise balance, and a tab.

An Adobe Acrobat (PDF) file of the entire report (1,806,812 bytes):




Full-scale wind-tunnel and flight tests of a Fairchild 22 airplane equipped with external-airfoil flaps

Reed, Warren D Clay, William C
NACA TN-604
July 1937
 

      Wind-tunnel and flight tests have been made of a Fairchild 22 airplane equipped with a wing having external-airfoil flaps that also perform the function of ailerons.  Lift, drag, and pitching-moment coefficients of the airplane with several flap settings, and the rolling- and yawing-moment coefficients with the flaps deflected as ailerons were measured in the full-scale tunnel with the horizontal tail surfaces and propeller removed. The effect of the flaps on the low speed and on the take-off and landing characteristics, the effectiveness of flaps when used as ailerons, and the forces required to operate them as ailerons were determined in flight. The wind-tunnel tests showed that the flaps increased the maximum lift coefficient of the airplane from 1.51 with the flap in the minimum drag position to 2.12 with the flap deflected 30 degrees. In the flight tests the minimum speed decreased from 46.8 miles per hour with the flaps up to 41.3 miles per hour with the flaps deflected. The required take-off run to attain a height of 50 feet was reduced from 820 to 750 feet and the landing run from a height of 50 feet was reduced from 930 to 480 feet.  The flaps for this installation gave lateral control that was not entirely satisfactory. Their rolling action was good but the adverse yaw resulting from their use was greater than is acceptable, and the stick forces required to operate them increased too rapidly with speed.

An Adobe Acrobat (PDF) file of the entire report (1,156,047 bytes):




Pressure distribution over an NACA 23012 airfoil with an NACA 23012 external-airfoil flap

Wenzinger, Carl J
NACA Report 614
1938
 

      Report presents the results of pressure-distribution tests of an NACA 23012 airfoil with an NACA 23012 external airfoil flap made in the 7 by 10-foot wind tunnel. The pressures were measured on the upper and lower surfaces at one chord section on both the main airfoil and on the flap for several different flap deflections and at several angles of attack.  A test installation was used in which the airfoil was mounted horizontally in the wind tunnel between vertical end planes so that two-dimensional flow was approximated. The data are presented in the form of pressure-distribution diagrams and as graphs of calculated coefficients for the airfoil-and-flap combination and for the flap alone.

An Adobe Acrobat (PDF) file of the entire report (694,457 bytes):




Wind-tunnel investigation of an NACA 23012 airfoil with various arrangements of slotted flaps

Wenzinger, Carl J Harris , Thomas A
NACA Report 664
1939
 

      An investigation was made in the 7 by10-foot wind tunnel and in the variable-density wind tunnel of the NACA 23012 airfoil with various slotted-flap arrangements.  The purpose of the investigation in the 7 by 10-foot wind tunnel was to determine the airfoil section aerodynamic characteristics as affected by flap shape, slot shape, and flap location. The flap position for maximum lift; polars for arrangements favorable for take-off and climb; and complete lift, drag, and pitching-moment characteristics for selected optimum arrangements were determined.  The best arrangements were tested in the variable-density tunnel at an effective Reynolds number of 8,000,000. In addition, data from both wind tunnels are included for plain, split, external-airfoil, and Fowler flaps for purposes of comparison.

An Adobe Acrobat (PDF) file of the entire report (2,092,753 bytes):




Wind-tunnel investigation of spoiler, deflector, and slot lateral-control devices on wings with full-span split and slotted flaps

Wenzinger, Carl J Rogallo, Francis M
NACA Report 706
1941
 

      Report presents the results of an extensive investigation made in the NACA 7 by 10-foot wind tunnel of spoiler, deflector, and slot types of lateral-control device on wings with full-span split and slotted flaps. The static rolling and yawing moments were determined for all the devices tested, and the static hinge moments and the time response were determined for a few devices of each type.

An Adobe Acrobat (PDF) file of the entire report (1,560,119 bytes):





Development of the NACA slot-lip aileron

Weick, Fred E Shortal, Joseph A
NACA TN-547
November 1935

An investigation of the undesirable delayed action, or lag, of the spoiler-type lateral control device led to the development of the NACA slot-lip aileron. The tests were made in the 7- by 10-foot wind tunnel with a 4- by 8-foot wing hinged at the tunnel jet boundary and taken of the motion of the control device under test and of the resulting wing motion. First, the lag, as affected by the fore-and-aft location of retractable ailerons or spoilers was determined. The lag was found to increase regularly as the spoiler was moved from the rear of the wing toward the front. Then a combination of spoilers and fixed slot was developed that, with the spoiler retracting into the forward part of the slot, reduced the time lag to a negligible value. In addition, an arrangement was developed using a hinged aileron-type flap as the upper portion, or lip, of a slot through the wing. This arrangement appears to be usable as a form of lateral control device that shows promise of giving improved control and stability at the high angles of attack through stall, with negligible lag, low control forces, and relatively simple construction.

An Adobe Acrobat (PDF) file of the entire report (928,323 bytes):