Thanks Arne, I was given an Albacore 15 without sails and most of mechanical bits so it is perfect to Junk rig. I plan to go with your cambered design and Paul's Aerojunk. After I found that site on trimming the sails I realized that junk sails don't seem to have the same ability to optimumly adapt to changing wind strength and direction. When I said " one size fits all" I meant that camber shape was fixed for all wind conditions. At first look I assumed the aerojunk sail was the perfect design. But now I see it has its tradeoffs too.
Hi Cory, the usual prescription when designing a new junk sail is to make the area larger than the original as any junk can be reefed easily. Also the Centre of Effort (or Centre of Pressure) of the sail is higher up than a Bermudan. This alone will suggest an early reef.
If you accept that then, particularly with a wishbone junk, you can make each panel with a reducing camber as you ascend from the boom to the yard. In this way, when the wind rises and it is time to reef, you will be left with increasingly flatter cambers and reduced drive. This is the equivalent of finely tuning a Bermudan sail. Except that it all happens automatically as you reef the sail.
With wishbone battens you already have reduced width for each upper batten (because of the geometry of the 'lazy-jacks') so even with a perfectly square sail-outline the sail becomes flatter and more suited to stronger winds the higher up the sail.
With Miranda I find I can still get maximum hull speed and the ability to tack between 85 and 90 degrees in a F4 with one or two reefs. That's good enough for me so it depends what you are looking for.
Regards, Paul