Our Cozy Project
Construction Extras Modifications Pre-build Tips Videos


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Left winglet with a piece missing - oh yeah - that's the rudder!

Left wing / winglet outside tapered layup curing.

Left lower winglet attach layup curing

Turtleback inside layup curing

My own TB1 design for Side Hinging, Electrically Actuated canopy

Turtleback and canopy test fit for photo

Bracket for AeroSun 1600 LED landing / taxi light

Close up of Delrin pivot block for "hung" rudder pedals

Mock up of whole airplane - assembled for recent builder's tour

The gallery above is an attempt to share what's currently being worked on.

Winglets & rudders are in progress & I continue on the Canopy, chapter 18. 

Check out the mock-up my son and I did for a recent builder's tour - it's starting to look like an airplane!


What's a Cozy Mark IV?

    What's a Cozy Mark IV?  Why would anyone want to build one?  Why would anyone want to consider building an airplane anyway?  Fair questions, of course, and this introduction is intended to answer them.

    What's a Cozy Mark IV?  A four seat, canard pusher single-engine aircraft built from composite materials.  Four seats because my family has more than four people (no five-seat canards available yet!), canard because it's more efficient.  Canard is the name for the small wing that's found in front of the main wing, actually the French word for goose.  Why is a canard-configured airplane more efficient?  It's simple, really, I can probably even explain it without going into some fairly complex aerodynamics.  Wings generate lift, but when they do, they also generate a moment, or twisting action, about their long axis.   This moment, Mac, called moment about the aerodynamic center, wants to force the wing to twist forward or front-down.  To combat that twisting effect or moment, "normal" airplanes have a tail in the back that generates lift down.   Therefore, because the main wing is generating lift up, and the tail is generating lift down (to combat that dreaded twisting moment) the combination of main wing and tail have to be somewhat larger overall to offset that negative lift of the tail, which does nothing to support the weight of the aircraft.  A canard-configured aircraft, however, has the "tail in the front."  Thus, the canard generates positive, or upward, lift to counteract that nose or front-down twisting moment yet contributes to the overall positive lift to support the weight of the aircraft.  Thus, the overall lifting surface, as compared to a conventional aircraft, can be lower and still support the weight.  This makes the aircraft's structure lighter, generates less drag (all lift that's generated generates drag, regardless if it's positive or negative lift) and makes the aircraft more efficient.

    The fact that it's single-engine probably doesn't need to be explained.  Composite means the construction is of a combination of materials in a matrix.  Concrete can be considered a composite, as an example, as the finished product is a combination of sand, gravel and the concrete mix or liquid we've all seen.   Separate, none of these materials could hold up the weight of your car in the driveway (at least without deforming) but together and cured they become very strong.   The materials this aircraft is "composited" from are foam, fiberglass cloth and epoxy resin.  The foam defines the basic shape of the parts (and separates the strength or weight-carrying fiberglass cloth), the fiberglass cloth carries the load (glass is actually quite strong in tension and compression) and the epoxy, once cured, holds the whole package together, aligned, straight, etc.  It should be noted, however, that these material are not the typical foams and fiberglasses and epoxies you're used to seeing.  They have been designed for and refined for use in high-strength aircraft applications thus are much stronger and much more consistent that what you'd see in a hardware store.

Why would anyone want to build one?   

    The paragraphs above do a good job of describing why a canard aircraft is more efficient than a normally configured one.  Still not convinced a canard is the better way to go?  Or, like canards but wonder why you should build?   The table below (some data in it comes from AOPA Pilot, March 2000) I feel answers those questions.


Top speed - knots

Engine, HP

Cost - $

Lancair Columbia




Cozy Mark IV




Mooney Ovation




Mooney Eagle




Socata Trinidad




Commander 114B




Cirrus CR20




Cessna Skyland








    *Of course, all of the above factory-built aircraft come equipped with new engines.  But, even if you equipped your Cozy with a new engine, the cost would only go up around $20,000, still making it the cheapest, by far, airplane on the table.  Further, a Cozy will typically sell for 2-3 times the cost it took to build.  I'm convinced!

Want to know more?

    If you'd like to know more, I encourage you to visit the FAQ page at Nat Puffer's site.  Nat is the designer of the Cozy and currently sells plans as well as supports his builders - here's the address:  www.cozyaircraft.com


Construction Extras Modifications Pre-build Tips Videos

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