Another question, if the hull is made a little shorter, is it still a springer?
If you wish to build to the springer rules from the States I think,
The hull should be 18x8 inches, 540 motor max, 7.2V max and no Korts.
It's early morning and this is from memory but I think it's right.
However, UK 'Springers' come in all shapes and sizes and all specs.
From 6 inches long to manic brushless.
The standard size however seems to be about right and as you need a lot of
ballast, two SLA batteries 6V 4.5 anp gives about the right amount of ballast
and lots of run time.
Mine has a steerable Kort but I think the rudders with the triangular fillet on
the trailing edge and top and bottom plates would be just as effective and still
be in the rules for the springer olympics
There is a wealth of reading and knowledge in the Springer Section on here.
Go for what you think is right and most of all HAVE FUN