let me first start by explaning why Hitec servos are the worst servos for your RC application. First reason is, they are over priced. Sure 10 years ago where no other company sold servos, Hitec was the way to go, but today, one can buy 4 servos with the price of one Hitec servo, and yes im talking about HobbyKing servos which are of great quality considering the Hitec sesrvos are also manufactured in China ;).
So here are some servos i suggest.
HXT900, one of the most famous and the best value micro servos available. These servos are much stronger than the HS55′s, they do not strip as easy, the plastic they use for the gears are much stronger, speed of the servo is much faster and torque is much more at 1.6kg-cm, HS55′s are at 1.3. Believe me i have tried both servos and this is a no brainer, the HS55′s cost $15 and the HXT900 costs $2.50
Size : 21x12x22 mm / 0.74×0.42×0.78 in
Voltage : 3v ~ 6v
Weight: 9g / 0.32oz
Speed : 0.12 sec/60(4.8V)
Torque : 1.6 kg-cm
Working Temp : -30C~60C
Teflon Bushing, 15cm wire, coreless motor
Servo arms & screw included
I use this servo on all my delta wings that travel over 100+ miles an hour, these servos are fast at .08 seconds, the gears are metal so they do not strip even on the hardest crash, its Torque is at 2.9kg @6v. The D-MG16 does have a little bit of play out of the box, but that doesn’t bother me all that much as the speed and torque and over all strength of the servo along with the price outweigh the tiny play. o ya, these servos are digital as well.
Our new favourite servo. The D-MG16 packs a high-torque punch while weighing less than 20g!
Excellent for park-flyers. These servos cost only $8.50
Torque: 2.9kg @6v
Voltage: 4.8 to 6v
Size: 29 x 11.2 x 29mm
MKS DS470 Digital Servo at $23.40 is another one of my favorites. Although the price might seem steep, compare them to the HS65 which cost $26 a pop, this is another no brainer. the HS65 is junk next to the MKSDS470 and here are a few reason why. The MKS DS470 weighs only 10 grams, at 4.8 volts, it outputs 2.37 Kg.cm of torque, a super speed of 0.089s/60° which is perfect for your heli tail servo, it offers metal gears and yes its Digital.