Wednesday, January 16, 2013

Old ideas being revisited: design nr. 2

Let's have a look into a more conventional solution.
The dream is always the same: being able to foot-launch from a hill with the highest possible gliding performance. In other words, that means reducing drag to the minimum, and in order to do so, wetted area must be reduced to the minimum in order to reduce parassite drag. Profile and induced drag are to be minimised by working on the right wing section selection and wing platform configuration. In that specific case, since the architecture is close to a traditional one, wing platform should be optimised in order to get closer to an elliptic lift distribution.
In the next pictures, i've sketched some design variation of the same basic concept:
Picture 1: v-tail
All those design variations are probably too aggressive in terms of wing area. I'm quite sure that a bigger wing surface is required to reduce stall speed to a reasonable value. In comparison with a tailless design there is one advantage: the CLmax of a traditional design can be significantly higher respect to an equivalent tailless design. Should also be easier to implement a flap system that can maximise CL during take off and landing. The fuselage pod has been pushed to the minimum wetted surface: probably needs to be enlarged a bit. An amazing concept is represented by the pilot prone position, giving an outstanding visibility. The biggest drawback is that no-one will feel comfortable having is nose being the first part crashing in case of ground impact...
Picture 2: v-tail
The second picture is more or less showing the same concept.
Picture 3: traditional tail configuration

Third picture shows a bit more traditional configuration for the tail. One of the potential design issues is connected with the short tail harm. This can be achievable only using low Cm wing sections and a big tail area. Unfortunately a low Cm sections usually is also having a low CL max....
A solution could be to increase tail authority by designing a quite extended vertical fin.
Comments are more than welcome!

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