"Actually "mission" drives aircraft design. The airframe and powerplant are typically flexible until just before PDR, then locked in. Its true that homebuilders will sometimes select an airframe or (design one) based upon an engine laying around the shop, but thats not "design" in the pure sense. ...
Not quite. Wing thickness (in %) may be driven by mission but not by speed part of mission. For instance, Boomerang does not look particularly thick, but it’s wing is 17% thick. Burt kept making it thicker until range (fuel capacity) was met. I think we can agree that the Boomerang qualifies as long range and fast…I agree with others, mission drives the design. All design projects are to meet the mission. You wouldn't build a carbon fiber sweep wing retractable low wing for STOL, nor would you build a thick, wide, long aluminum high wing for XC flying. Any powerplant can fit any mission, if the airframe accommodates. The reverse is not true.
Digressing into history here ....It seems like when I read the history of a lot of World War II aircraft that they will not the airplane that we think of until some particular higher horsepower engine or modification came along.
Not quite. Wing thickness (in %) may be driven by mission but not by speed part of mission.
Actually, the opposite is usually true - there are multiple engines capable of satisfying the mission. This was the case for my last design team. The Government stated the performance goals and we the designers had to do a very painful trade study to weed through the engine choices until we found the one that gave us a favorable market advantage. In this case we found an engine that not only gave us some margin back in the payload, but also was a logistics win because it was the same engine used in an already large fleet owned by the government.But what good is it to design anything without a engine capable of driving it ?
Someone say "Hot Rod"?""
Shoving any old engine into a frame is merely "hot-rodding."
As in my B-17 example you can choose to use more than one available engine...like 2 (Martin and Douglas) or 4 (Boeing).But what good is it to design anything without a engine capable of driving it ?