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Well-Known Member
Apr 24, 2014
Flint, Mi, USA
Welcome to the forum.
I knew Vern Seifert for years and talked about his ideas. His modified L-2 had bumps on the wings like the wing flippers on big whales. The L-2 had house carpet on the top of the wings for boundary layer control tests.
IIRC the bumps are basically leading edge vortex generators that increase the stall angle by a huge amount. Lets them turn their big bodies really hard with their flippers without creating tons of drag.


New Member
Nov 12, 2020
Apteroid 3.jpg
Vernon Siefert's Apteroid - third version​
Apteroid 4.jpg
Vernon Siefert's Apteroid - fourth version​
Apteroid 5a.jpg
Vernon Siefert's Apteroid - fifth version​
Apteroid 5b.jpg
Vernon Siefert's Apteroid - fifth version​

Hello Everyone,

In an earlier post, where this bizarre homebuilt had been ID'ed, I referred to the May 1967 issue of "Sport Aviation", which contained an article about the craft. Happily, a copy of this very magazine has now made its way to me. Said article, "Apteroid Experimentation", is quite a useful source of information. It not only contains the four photographs seen above, but the brief text helps to clarify the timeline and development of Vernon's flying machines.

The craft shown in the November 1966 "Popular Mechanics" article is the third version of the Apteroid. In that article, the engine is shown slung underneath the wing platform but, as per the first photograph, at one point it had been positioned above the wing.

The second photograph shows the same craft that's in the colour photos at the start of this thread; it's now clear this is the fourth version of the Apteroid. The colour photos themselves can be dated to perhaps late 1966 - early 1967.

The article also makes clear that the third and fourth versions of the Apteroid were fitted with curved aluminum plates on the sides of the wing, these acting as slots. The registration isn't N-4242, as I'd thought, but N-424Z. I'd originally thought that the entire wing on the fourth version had been inverted, but it seems more likely now that the curved aluminum plates (and painted with the registration number) simply had been removed off the third and then installed upside down on the fourth; which explains why the rego number is inverted.

The article also contains two photos of the fifth version of the Apteroid; this is a wholly different beast to those that had preceded it. It almost looks 'designed'! The center wing platform is made up of a 'three-stage airfoil', which may seem strange, but the idea's been around for quite a while. Hiram Maxim wrote about the concept in his 1908 book "Artificial and Natural Flight". The two outer panels, outboard of the wing, seem to be fixed in place, but according to the article, at some point they "will be made to fold in and form a center high-speed cone for higher performance".

The article also mentions that the Apteroid was first reported on in the September 1964 issue of "Sport Aviation" - so I am now on the hunt for a copy of that!

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