The Design

The Cozy Mark IV design is a straight forward modification of Burt Rutan's very reliable LongEZ. In this sense, toghether with the VeryEze and the LongEZ the Cozy Mark IV is the most popular plans-built 4-place in the world (per Kitplanes) and probably the most thoroughly tested. There are between 35 and 40 Cozy already flying in the US. The safety record is twice as good as a Cessna. It was tested first throughout and beyond its c.g. range by Jim Patton and Nat Puffer, and written up in Sport Aviation in 1995.

It was tested by Ed Kolano (he is doing a number of flight evaluations of homebuilts) in July and will be published in Sport Aviation, and Mark Beduhn submitted his Mark IV to the CAFE 400 people and he told me that they were amazed because the performance came out exactly according to our Owner's Manual, which usually wasn't the case. If you check one of our recent newsletters, one of our builders tested the canard to 4 gs and it deflected 4" without any visibile signs of strain, but the builder did not go any further. It is built the same way as on the Long EZ and that canard was tested to 14 gs (14" deflection) before it failed. By the same comparison, the Mark IV wings should be good for 12 gs. One of the builders, reported in the newsletter, had the engine mount evaluated by a structural engineering company, and it was found, at its weakest point, to be about 25% greater than required by FAR 23. We have over 235 III and IV place flying and no reported cases of flutter. The IV is much stronger (main landing gear, nose gear, wings, engine mount, etc) than the Long EZ and Cozy III.

Unfortunately this is not enough for us in Europe and Switzerland. We have to go for additional engineering efforts and need to make a complete load test, too.

The Plans

For historical and practical reasons the plans with the construction manual is split into 2 sections with a total of 26 chapters.

Index

    done.

    under construction.

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e-mail: Kurt.Schumacher@schumi.ch
All Rights Reserved. Copyright © 1998, Kurt A. Schumacher
Last update: 27. Oktober 1998