A tandem wing aircraft has two main wings, with one located forward and the other to the rear, both wings contribute to lift. A lower first wing is located at the forward end of the fuselage attached directly to fuselage structure. A second higher wing is located at the aft end of the fuselage. Pitch control is achieved by increasing or decreasing the lift on either wing. In a tandem wing design the lift vectors on the two wings are spread far apart longitudinally, allowing them to act together to achieve stability and control. The two wings are preferably vertically separated by 25% to 50% of the span of the wings. Control redundancy for flight safety is achieved because of availability and location of control surfaces. Higher aspect ratio wings can be used because of inherently reduced bending moments on the wing and overall aircraft gross weight is reduced due to structural and aerodynamic efficiency. This is different from a biplane, in which the wings are stacked more or less vertically, one above the other, such that their lift vectors are very close together and a separate horizontal stabilizer surface is required, placed well forward or aft of the main wings. It differs from the canard or "tail-first" configuration in that the forward wing contributes a major part of the lift, typically close to 50%. 1.1 History:
Peyret - Maneyrol, a first success,
In 1907 Louis Peyret, a French engineer, made a model with nearly identical wings. In August 1922, a glider competition in France at Combegrasse (close to Clermont-Ferrand): The French pilot Alexis Maneyrol was also in the competition, but he made no chance because of his bad glider. Peyret came in too late with his tandemwing to be a part of the competition. It was the only tandemwing in the competition. After a time of one month, Maneyrol made several flights in the glider. He thought it was a stable airplane. Together with Peyret and his assistants they made a glider especially for an international glider competition, organized by the Daily Mail. It got the name Alerion Peyret. Alerion was a common name for any airplane at that time in France. They always placed the name of the designer after the word "Alerion". One thing is remarkable about the gliders construction. It had on each wing full span control surfaces. You can see it better on the pictures of the "small" model lower on the page. If you pulled the steering stick, the front wing surfaces went down and the rear wing surfaces went up. If you pushed the stick, the opposite happened. If you pushed the stick to the right, the surfaces of the right wing went up, the ones on the left wing went down. The advantage of this system is that you don't need trim.
Fig1.1 History of Tandem wing planes
It won the competition. It even broke the record of longest glide. It became now 3 hours and 22 minutes. Peyret and Maneyrol became immediately French heroes. And they received the price money of 1000 Livres Sterling. Maneyrol was warmly congratulated in London by Monsieur Laurent-Eynac. At arrival back to Paris, they were greeted by a mass of enthusiasts. Maneyrol was carried about like a big winner. Both got medals by the Federation. A story about victory. Not so long later, Maneyrol broke the record again in the same Alérion Peyret. This time is became 8h 4' 50'' 2/5. Victory again. Not much later Maneyrol broke the distance record. Victory again. But tragedy stuck and stuck hard. It was during a attempt to break the record of height that Maneyrol got killed. It was not in the Alérion Peyret. The wings broke in mid air after having reached to an incredible height. But the barograph got damaged in the accident and the record never got official.Later, he made the "Taupin", a motorized tandemwing that flew perfect! 1.2 Tandem Wing Technicalities:
The following drawings show some of the forces in a conventional airplane and in tandem wing....
References: 1. FLUENT User 's Guide, By ANSYS Inc, 2008
2. Philip C. Whitener, Boeing, "Tandem Wing Airplane" U S Patent Document
3. Scaled Composites Proteus, Northrop Grumman Corporation
4. Summary of Low Speed Airfoil Data, University of Illinois at Urbana Champaign
5. Database of Airfoils, university of Illinois at Urbana Champaign
6. C. Wauquiez, "Shape Optimization of Low Speed airfoils using MATLAB".
7. R J McGhee, NASA, "Low Speed Aerodynamic Characteristics of 17% thick Airfoil"
8. John D. Anderson, "Computational Fluid Dynamics", McGraw Hill
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