Building My Cozy Mark IV
Why this site exists
I’m building in public so others can catch my mistakes, offer tips, and to help future builders avoid the same problems. If you see something off, please tell me. I would like the feedback.What is a Cozy MK IV?
The Cozy Mark IV is a four-seat, canard-style, pusher-propeller homebuilt aircraft designed by Nat Puffer. It is a plans-built composite airplane known for aerodynamic efficiency, stable handling, and the distinctive canard configuration (a small forward wing).
- Four seats: pilot plus three passengers
- Canard layout helps reduce classic stall behavior
- Rear-mounted engine in a pusher configuration
- Composite construction: foam, fiberglass, epoxy
| Specification | Typical Value |
|---|---|
| Seats | 4 |
| Engine | Lycoming O-360 (180 hp typical) |
| Cruise Speed | ~185 mph (about 160 KTS) |
| Stall Speed | ~65 mph (about 56 KTS) |
| Range | ~1,000–1,200 miles |
| Rate of Climb | ~1,500 ft/min |
| Service Ceiling | ~18,000 ft |
| Empty Weight | ~1,050 lb |
| Gross Weight | ~2,050 lb |
| Fuel Capacity | ~52 gal |
| Build Time | ~2,000–3,000 hours (very builder-dependent, some are still sanding) |
How is it built?
The Cozy Mark IV is built using moldless composite construction. Builders shape foam cores and lay fiberglass cloth over them with epoxy resin. Once cured, the structure becomes lightweight and strong.
Typical build phases
- Build fuselage structure and bulkheads
- Construct canard and main wings
- Install controls, wiring, fuel systems, and avionics
- Mount the rear engine and propeller system
- Finish work: sanding, fairings, paint, and final assembly
No two builds are identical. My goal is to document the real process, including mistakes, fixes, and what I would do differently next time.
What is its history?
The Cozy family traces back to the 1980s, when Nat Puffer developed Cozy designs inspired by the canard aircraft movement popularized by Burt Rutan. The four-seat Cozy Mark IV was introduced around 1990 and became one of the best-known plans-built composite aircraft projects worldwide. As of October 2025, at least 1888 Cozy Mk IV plans have been sold. Ask me how I know 🙂 .
Warning: Amateur at Work!
This site documents my Cozy MK IV adventure, complete with mistakes, triumphs, and probably a few “what was I thinking?” moments.
I’m not a professional builder, mechanic, or structural engineer.
If you choose to follow my lead and end up glued to your workbench, that’s between you, your epoxy, and gravity.
Build smart, stay safe, and never skip the plans.