October 24, 2015

Planet Satellite: An aeronautical engineer responds

Image: Flight Global/http://xplanes.tumblr.com

I had not heard of the delightfully oddball Planet Satellite before reading about it on Hush-kit, but admit to now being something of a fan.

Despite being a postwar design it does have hints of the “aircraft of the future” generally found in the “Boy’s Books” of the late 1930’s. I also presume I am not the only one who sees parallels with certain aspects of the recently resurrected Bugatti racer? Of course, no matter what qualities the aircraft may have it is the human angle that draws us in. Something that the Satellite has in spades. The disingenuous nature of the claim regarding Heenan’s complete lack of aeronautical background is immediately apparent as soon as you look at the aircraft. It is unusual but the proportions and overall configuration look “right”, or at least “highly plausible.” The obvious flaw retrospectively was not rigorously following a professional design and development process for the project. Given that the aircraft had the novel use of material and construction this can be seen as being highly naive at best. It smacks less of an engineer without aircraft experience and more of someone who has been around aircraft but having no formal engineering experience.

The governing bodies had obviously learnt their lesson by the time the Lear Fan turned up. Looking beyond the aircraft layout the striking similarity is the use of novel materials and construction, this time bonded composites. It just so happens that I have some experience in this field and I recall being told that the reason the Lear Fan had 3 wing spars was because the FAA was rather twitchy about the use of the new material. This way if there was a catastrophic failure of one spar there were at least 2 more to get you home on. The FAA also insisted on “chicken bolts”, secondary mechanical fasteners passing through the bonded joints. Sadly the best way to weaken a piece of composite is to put a hole through it – still, never mind. Perhaps the Satellite was failed by too little regulation and the Lear Fan by too much?