Hummel Aircraft - Here is an Ultracruiser completed by Steve Grensky and a build partner in Grants Pass, OR, that uses a Hirth F23 engine. Sounds like it was finished around October
Airplane For Sale - Hummel Ultracruiser Project | Homebuilt Aircraft & Kit Plane Forum
Hummel H5 Walk-around and Autopilot - YouTube
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Flight Review: What's Hummin' at Hummel?
Long-Lasting UltraCruiser Fun Plane - ByDanJohnson.com
Airplane For Sale - Hummel Ultracruiser | Homebuilt Aircraft & Kit Plane Forum