David, the Spring Air web site doesn't give any info about their retracts. I can not determine which series would be right for a .60 size, 5-10 lb., pattern plane. I'm guessing the 200 or 300 series but they don't even tell you what size wire they use for the strut.

The one thing I do have against spring air is the need to use an air tank which can be tough to accomodate in a narrow pattern plane. There is also the extra weight.

Bob