oriol
Well-Known Member
Hi!
At the begining of Niu's Airframe's structures book, there are three funny drawings that reflect the compromises aircraft design has to achieve. By focusing in the most resistant and simple structure, I like the Airtruk, or the Durand Mark V approach. They both remind a truss bridge. Which is nice, because it can be analized with very simple formulas. The drawback is perhaps that this configuration is probably not the best for a glider project, which is what I am up to.
However if one eliminates the lower wing, but keeps the struts. Perhaps it is possible to achieve a very unusual compromise. Achieving enough Aspect Ratio, that will allow for some modest soaring capabilities; at least as good as a paraglider. Also by connecting the struts with real hinges. It will be possible to split the "half wings" in three separate sections. I am considering each section to be of 1,5 m span and 1 m chord (5 ft * 3,2 ft); this will result in a surface area of 10 m2 considering the cabin. Which on the other hand, might allow for a very compact wing for storing; without considering the fuselage. The aircraft might be a flying plank, this will involve reading Nickel and Wolfahrt's book, and building plenty of RC aircraft for testing, or a three axis aircraft, with a non folding fuselage. This glider concept is an hibridation between a paraglider, and a basic primary glider.
At the end there is a sketch of the glider, it looks like an inverted truss bridge. The structure can be of aluminum tubing, like the Goat. Between each section there can be a solid aluminum tube part, housed inside the tube, like those used to connect hang glider triangle bars. One option would be that of covering the wing sections with Oratex. Then between the sections, the hinges would have to be covered with a removable skin, which is not a trivial issue. Pehaps dacron with velcro tape?
Another fundamental issue might be the lack of rigidity. Pehaps if flying at low speeds flutter is not an issue?
The whole concept is uncharted territory. If one does not need to escape from Alcatraz, why bother? Perhaps the structure simplification is suboptimal in all other aspects. I probably need to learn more about structure analysis, no matter what, and then be able to design a cantilever folding wing. A first project that consists in a foldable three section half wing, looks intimidating. However, I do not have to reinvent the wheel. I can figure out a folding wing system, similar to the Onex. And perhaps add a strut, to provide more strength, while at the same time keep the weight low. It seems simple to describe, but of course there are plenty of nuts and bolts.
What do you think, am I being foolish?
Cheers,
Oriol
At the begining of Niu's Airframe's structures book, there are three funny drawings that reflect the compromises aircraft design has to achieve. By focusing in the most resistant and simple structure, I like the Airtruk, or the Durand Mark V approach. They both remind a truss bridge. Which is nice, because it can be analized with very simple formulas. The drawback is perhaps that this configuration is probably not the best for a glider project, which is what I am up to.
However if one eliminates the lower wing, but keeps the struts. Perhaps it is possible to achieve a very unusual compromise. Achieving enough Aspect Ratio, that will allow for some modest soaring capabilities; at least as good as a paraglider. Also by connecting the struts with real hinges. It will be possible to split the "half wings" in three separate sections. I am considering each section to be of 1,5 m span and 1 m chord (5 ft * 3,2 ft); this will result in a surface area of 10 m2 considering the cabin. Which on the other hand, might allow for a very compact wing for storing; without considering the fuselage. The aircraft might be a flying plank, this will involve reading Nickel and Wolfahrt's book, and building plenty of RC aircraft for testing, or a three axis aircraft, with a non folding fuselage. This glider concept is an hibridation between a paraglider, and a basic primary glider.
At the end there is a sketch of the glider, it looks like an inverted truss bridge. The structure can be of aluminum tubing, like the Goat. Between each section there can be a solid aluminum tube part, housed inside the tube, like those used to connect hang glider triangle bars. One option would be that of covering the wing sections with Oratex. Then between the sections, the hinges would have to be covered with a removable skin, which is not a trivial issue. Pehaps dacron with velcro tape?
Another fundamental issue might be the lack of rigidity. Pehaps if flying at low speeds flutter is not an issue?
The whole concept is uncharted territory. If one does not need to escape from Alcatraz, why bother? Perhaps the structure simplification is suboptimal in all other aspects. I probably need to learn more about structure analysis, no matter what, and then be able to design a cantilever folding wing. A first project that consists in a foldable three section half wing, looks intimidating. However, I do not have to reinvent the wheel. I can figure out a folding wing system, similar to the Onex. And perhaps add a strut, to provide more strength, while at the same time keep the weight low. It seems simple to describe, but of course there are plenty of nuts and bolts.
What do you think, am I being foolish?
Cheers,
Oriol
