Once upon a time, a long time ago, Skyboy asked a sensible question. I guess it deserves a sensible answer!
I know the original HM14 design had an unfortunate propensity to develop an unrecoverable dive (if negative pitch was greater than minus 15 degrees) but did anyone ever fix the design fault and did this produce any flyable fleas? I have seen a couple of taxiable fleas in the UK but wonder if there are any (anywhere in the world) that get airborne.
Sorry Skyboy, you’ve only got me, but I’ll do my best! I’ve got a bit of an interest in the beasts as the Luton Minor I fly was effectively a post-flea design with a longer fuselage and normal wings. (Comments sure to follow on its airworthiness from TT!)
The problem, as you said, in the 1930s was that the tandem wing design developed a fatal flaw in that, at certain angles of attack, the front wing acted as a slot for the back wing, which then relatively produced a stonking amount of lift, pitching the Flea, regardless of control input, into an outside loop.
I’m not sure whether they were formally banned, but it sure as heck quashed any future popularity – and the onset of war did the rest.
Over in France though, Henri Mignet had cured the instability problem relatively quickly by moving the wings further apart and altering the way the front wing was controlled. Flea building has continued non-stop since the 1930s over there.
There’s at least one ‘modern traditional’ Flea on the UK register, HM-293, G-AXPG which lives down in Sussex. There’s a picture of it on the CAA G-INFO website: http://www.caa.co.uk/applicationmodules/ginfo/ginfo_photo.aspx?regmark=G-AXPG&imgname=G-AXPG001&imgtype=JPG
There are also at least half a dozen HM1000 Balerits on the register. These are a modern tandem-wing microlight, using the same philosophy and Ithink, designed by Mignet’s son or grandson. http://www.caa.co.uk/applicationmodules/ginfo/ginfo_photo.aspx?regmark=G-MYDZ&imgname=G-MYDZ001&imgtype=JPG
Hope that’s a help!
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