Originally Posted by
duopar
My only worry is whether there would be enough friction and clamping force to keep the fork from slipping and rotating around the crown. One advantage would be that it would be possible to install a disc brake on this since the front axle position is fixed relative to the disc tab.
This is exactly why I wouldn't do it this way. A fork crown undergoes big forces and any sort of clamped joint is not going to hold for long term use.
There are some people making their own lefty forks. You might be able to make a motorcycle style fork that is adjustable.
Any way you do this it's going to require careful design. Brakes are an issue with multiple dropouts, no doubt. One approach for disks would be to make an insert like the rear adjustable brakes that would move with the chosen dropout. For example,
This one
A unicrown fork costs $50 plus whatever the dropout costs. An adjustable crown will cost hundreds in machining. You can build many forks for that. I don't doubt there have been some weird recumbent designs in the past, but I am also familiar with a number that use fairly standard front ends, i.e. road forks. I'm not sure why you would go all experimental when that seems to work fairly well