Its not in Alcúdia, but southeast of it
I'll give you a new zoomed-out link:
http://maps.google.de/maps?f=q&source=s_q&hl=de&geocode=&q=pollensa&ie=UTF8&hq=&hnear=Pollen%C3%A7a,+Balearen,+Spanien&t=h&ll=39.789676,3.236332&spn=0.130849,0.264187&z=13
Its the part of the coast northeast of Betlem in the lower right part of the linked Google map
Right, I think I get you: you must be north of Betlem pointing southish - that would give you the curve on the left of the pic and not on the right. I've done a lot of calendar shots (on the website) using the beach further towards Son Serra from your probable viewpoint. If you go into my Gallery 2, shot numbered "11 of 42" is shot in that area; the mountains behind the girl lead on, to the left, to the headland of Cabo Ferrutx, which is where I think you were. Under the mountains there, you can find a tiny harbour which I've been to by boat; there's supposed to be a track to it, but we never did find one that was driveable by car. No military presence in that area, as far as I know.
If you return, whatever you do, resist the temptation to swim off that beach between Son Serra and Colonia San Pedro: we almost died there, only about thirty feet out. The currents are vicious; in our case, we suddenly found no bottom. I could swim quite strongly when I was young, but my wife never was that good at it. Anyway, she panicked and tried to turn back to the shore. I thought I'd better accompany her back, and discovered that we were both holding position at best. Getting tired, I realised we were not going to make it that way, so I thought of going under and seeing if I could hit bottom. I could, and the answer for us was that I'd sink down and then spring back up off the bottom and push her towards the shore in a series of such launched pushes. If I'd been thinking rationally, I'd simply have swum sideways until we passed the hole and found ground again. Or not.
The restaurant owner we knew at Serra Nova told us that people died there every year. Just by the restaurant there is a flagged area that's supposedly safe...
Rob C