Mart,
My previous posting obviously needs some clarification, or elaboration, regarding hover.
- The Advancing Blade Concept (ABC) allows for dissimilar thrust between the 'advancing' and the 'retreating' sides of the rotors. During hover, each of the intermeshing rotors will be asked to produce 2/3 of their lift on their outside (advancing side during cruise) and 1/3 on their inside (retreating side during cruise). This will result in a relatively uniform induced velocity over the total effective disk area.
- As previously mentioned; during hover, the induced velocity directly over the fuselage, will be further reduced due to the inclusion of Active Blade Twist.
These are two very significant advantages that the Coaxial-ABC cannot exploit.
In addition,
the intermeshing configuration is proposed for transportation requirements. In this capacity a significantly greater portion of the craft's time will be spent in transit v.s. hover. In cruise the advantages of an Intermeshing-ABC configuration will again be greater then those of the Coaxial-ABC, AND those of the Intermeshing-ABC.
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As long as ideas are kept practical, i have no problem with technical challenges. A good idea should be able to survive on its merits - X2 is a good idea...
In addition. I have three practical concerns about the merits of a small or medium Coaxial-ABC, which are also of some concern to the Intermeshing-ABC.
One concern:- Consider the high disk-loading of the coaxial rotors, as shown in the above pictures. Then consider that the pusher prop is at the rear of the combined disks. It will be 'pulling the rug out from under this disk'. In other words, the propeller will be stripping a significant portion of the 'lift' out from under the two rotors.
Dave