MJD

My Feedback: (1)

You can do it the same way as a conventional aircraft, but the tail volume is zero. In this case, you work out the aerodynamic center of the wing, and since there is no tail surface the NP is there as well. Then you move ahead from that point with your desired static margin.

I used 15% since it is generally a pretty conservative setting and keeps pitch sensitivity sane-o for first flights. Usually.. barring other factors. IIRC Lennon generally recommended 12-15% for deltas (where is that book)? Maybe it was 10-12%.. in any case, that's what experimentation is for.

Soarrich's method comes out farther back but ahead of the NP, at least on this example - the taper ratio will affect it's position relative to the calculated one, but if it looks like a typical delta you'll be pretty close! In this example, it seems to be maybe what, a 7-8% margin or so in this case? That will work and will fly more efficiently for sure, though I am not sure I would go there on test flights, that's a personal choice. Optimum position is the rearmost one that gives you the stability you can tolerate - IOW, the closer the CG is to the NP, the more efficient since the download to counteract pitching moment becomes less and less. So does your stability margin.

Here's a crude picture, plus a scan from a handy reference - all of these layouts can be worked out the same way as a conventional aircraft. Find AC(s) - locate NP - add static margin.

MJD