SVSUSteve
Well-Known Member
cluttonfred said:
I'll give you the quick rundown as I am quite tired at the moment. My original comment about Thurston's book being outdated is that it simply repeats, insofar as crash survivability is concerned, a lot of the same things folks have traditionally believed. It could lead someone who isn't up to speed on newer research on the topic into designing an aircraft that is less than ideal. They are both good books which I use considerably in my own project but the one on safety, while better than most, is showing its age.
Basically, the drawbacks to the visibility approach Thurston takes are simply that he advocates for it in a way is counter to maintaining a survivable cockpit volume. A broad, sweeping expanse of Plexiglass or Lexan is nice and all but given the inherent limitations of see and avoid due to human physiology, there's not much to be gained from it and much to be potentially lost in the much broader set of circumstances that lead to crashes.
The one thing he does a great job of discussing in one of his books, which is often overlooked, so far as visibility goes is the need for over the nose visibility. It may be the one argument for a pusher configuration that actually has some real tangible validity although one could conceivably achieve the same end result without having to resort to a pusher configuration. Over the nose visibility has been a headache in the Praetorian project.
Spin/stall resistance....I am not an aerodynamics guy so my input on this aspect is limited. That said, as nice of a goal as it is, true spin/stall resistance is difficult to achieve in a way that doesn't have so many trade offs as to be more trouble than it is worth. The more practical approach is a combination of producing an aircraft that has very gentle stall characteristics, have it flown by a competent pilot. If one is feeling quite aggressive about this, the use of a stick pusher device to place the aircraft slightly nose down when a stall is encountered might be feasible. It's certainly less of an engineering challenge especially in an aircraft with a glass cockpit.
Engine location is, in my book at least, pretty easily settled by the decline in performance and noise inherent with a pusher configuration. The fact that producing a crashworthy fuselage in either arrangement requires a substantially strong firewall to keep the engine out of the cockpit and/or cabin really cancels out that argument for or against a pusher configuration...if one is bothering to put in such a substantial bit of structure.
