I attended a contest under new rules that mandate the use of Sig Shoestring or Buster kits.  There was some talk of the boredom of only two designs and the fact that a Buster won.  I did some study of the 1/8 scaling of Goodyear racers.  I noted that one modeler rather casually mentioned the intentional use of the -5% tolerance.

The following numbers are listed in this order:  Model, -5%, true size, +5% and Sig kit size.

Buster 21.5", 22.7", 23.8", 24"  (conclusion, the Sig kit is oversize illegal)
Shoestring 27.1", 28.5", 29.9", 28" (conclusion, the Sig kit is within tolerance on the small side)

It looks like if I want really small, a 95% Cassutt could be built with a 19.5" span.  But i'm not really sure smaller is better in this case.

OK.  So paragraph 2.2 says "minimum" consistant scale of 1/8 and it also says +/- 5%. 

So they could be legal if they built the whole airplane bigger than 1/8 scale and the wingspan was within 5% of new, bigger scale.

I attended a contest under new rules that mandate the use of Sig Shoestring or Buster kits.  There was some talk of the boredom of only two designs and the fact that a Buster won.  I did some study of the 1/8 scaling of Goodyear racers.  I noted that one modeler rather casually mentioned the intentional use of the -5% tolerance.

The following numbers are listed in this order:  Model, -5%, true size, +5% and Sig kit size.

Buster 21.5", 22.7", 23.8", 24"  (conclusion, the Sig kit is oversize illegal)
Shoestring 27.1", 28.5", 29.9", 28" (conclusion, the Sig kit is within tolerance on the small side)

It looks like if I want really small, a 95% Cassutt could be built with a 19.5" span.  But i'm not really sure smaller is better in this case.

This analysis requires some clarification:

Over the course of its active career Buster was fitted with two different wings. When first rebuilt from the remains of Chief Oshkosh the plane had a 16 ft span wing. For the 1948 racing season the racer was modified with a new wing more along the lines of Bonzo. The new wing had a span of 15 ft - 1 in. It looks like Paul picked up the data for the second wing. The SIG kit is dead on for the first version.