Hi Chris,
Some aircraft need installing manually here's how:
I find that the easiest way is using this conversion/installing tool:
http://aeroflypro.com/installer/. Just click on "Download Installer Now" next click Open on the file download. Double click on the Zip file: AFPD_Import_Wizard.msi if it comes up with WinZip Caution... click Yes and follow the on screen instructions. Then download any AFPD plane you want and extract it into temperorary folder you must make a temperorary folder I have mine in "My Documents" and call it "AFPD downloads".Then get the application for AFPD Import Wizard up, select "Install New Aircraft". Then click next and select the location of your temperorary folder ie:"AFPD downloads"then click next again and follow on from there, then click next then finish its done!! You can load AFPD and the plane or heli should be there.
Hope this helps,
Greg.