Both are Ron Chidgy designed Tiger Tails ,the orange trimmed is built from the 1971 Model Airplane News plan; during that era Model Airplane News published a full construction article of each successive AMA nationals winner,this 'pattern ship' being the 1971 Nats winner. During those times designs were changing rapidly,so it was exciting to read successive construction articles on Nats winners during that era-- I still have this version (going on 20 years now.) the other is the last version the Tiger Tail IV- built in 1999 at that time I could not locate a YS, so I selected the 91 FX . The IV is currently being flown but a Dave Patrick Ultimate W/OS160 FX will be it's successor and my first IMAC airplane .