RE: Hitec coreless or hitec digital?
Luke..
The HS5625 is a digital servo with a cored motor. The HS-5945 is a digital with a coreless motor. To make it simple the HS56xx series is cored and the HS59xx series is coreless.
Both series are excellent servos and digital has certain advantages over a standard servo. You will have to check the specs on each one in order to determine which is best for your plane project. In my humble opinion I would say the HS56xx series is fine on planes 1.20 and a span of 78". The HS59xx series are great for any plane of 80" span or better up to 40% scale (depending on which of the two (xx) series you pick). Others will have a different opinion.
Also the 2 numbers after the 56 or 59 (xx) will indicate which servo has a faster speed or more torque. The HS5945's are rated for more torque so a lot of guys/gals use them on their 33%, 35% & 40% planes.
Another benefit of the HiTec HS56xx and HS59xx series is that they can be programmed. You can set the dead band, speed, fail safe, end points and even change the direction in which the servo travels (CW or CCW). You'll need the HiTec Model HFP-10 programmer to do it though.