3-Bladed Mid-Class Beast!
This article was originally published in RC Heli Pilot February/March 2016 issue.
Words By Chris Reibert
Photos By Jon Ottney
SAB broke all the molds of traditional styling of RC helicopters when they released their Goblin line of 3D helicopters. In the past few years I’ve built more than a few Goblin models. They all share the same aesthetics, feel, agility, speed, design and performance. The Goblin 570 Kyle Stacy Edition is SAB’s latest edition of the very successful Kyle Stacy Edition line of electric 3D class helicopters from SAB. When I first saw Kyle fly his Goblin 570 with the new three-bladed head I knew it would be a hit and that I was going to have to add one of them to my Goblin fleet to replace my existing 570.
NEED TO KNOW
MANUFACTURER: SAB Heli Division
DISTRIBUTOR: Heli Direct
TYPE: Electric flybarless 3D
FOR: Intermediate to advanced pilots
MINIMUM FLYING AREA:
RC flying field
PRICE: Airframe with blades $855.00
The SAB Goblin 570 is a true 550 class helicopter which allows the pilot the choice of either running a 6S or 12S power system, giving it a huge advantage over other 550 class helicopters on the market today. The 570’s robust two-stage transmission provides smooth unrestricted power through even the rigorous maneuvers. Don’t let its size fool you either; this machine can pull off any maneuver with ease!
FLYING WEIGHT: 2450g
LENGTH: 20.1 in. (510mm)
HEIGHT: 7.7 in. (195mm)
WIDTH: 3.0 in. (76mm)
ROTOR SPAN: 1218mm (with 540mm blades)
TAIL ROTOR DIAMETER: 278mm
MAIN BLADES: SAB 540mm Blackline
TAIL BLADES: SAB 104mm
CONTROL SYSTEM: 120-degree eCCPM
FLIGHT TIME: 4-6 min
NEEDED TO COMPLETE: 6+ channel radio, servos, motor, ESC, BEC, FBL gyro, receiver, flight battery and charger.
• HPS 3 Rotor Head (High Precision Head System) • Locking Battery Tray for 6S and 12S
• Uses Standard Size Servos
• Nylon Bolt Break Away System
• Two-Stage Transmission
• Strong Main Gear with Gates GT3 Motor Belt • Dampened Tail System
• Full CNC Aluminum Head and Tail
• Only one battery tray supplied
• Not enough height spacing on the rear electronics tray
OPENING THE BOX
If you have never built a SAB kit before you are in for quite a treat. SAB packs their kits unlike most helicopter brand kits I’ve built over the past few decades. The boxes and individual part bags are all labeled and correspond with the manual. When you open the box that houses the head, tail and transmission parts you will find them dis- played in beautiful foam trays securely protecting each CNC machined aluminum piece during the shipping pro- cess. SAB did not spare when it came to the manual either. It is a highly detailed color manual that in my opinion is the best man- ual I’ve ever seen included with a helicopter kit. The manual has amazing 3D photos of each step showing you where every part goes. It leaves little need for newcomers to search forum threads or YouTube videos for build help. At the beginning of each chapter a full page picture shows the parts break- down of what will be used in that section build. They even have a page dedicated to different pinion sizes and ratios as well as what motors and ESC combinations to use that will work best with specific headspeeds you want to achieve. The large vibrant colored canopy and tail boom are individually packed. Canomod did an excellent job on the paint work, stickers, and clear coat.
Material: Aluminum gear box and carbon fiber side frames
Type: Flat side frames with CNC aluminum standoffs and plastic bottom plate
Servo linkage type: Direct to swash servo linkage
Grips: CNC machined aluminum
Head block: CNC machined aluminum
Links: Rigid links
Swashplate: CNC machined aluminum with steel balls Mainshaft: 10mm high strength steel
Control: 120 CCPM
Drive system: Timing belt drive with spring tensioner Auto Capable: Yes, tail driven auto-rotation capable Tail Pitch Slider Type: Machined aluminum with brass sleeve
Tail Blade Grips: Machined aluminum with radial and thrust bearings
Tail Case: Carbon fiber side plates with aluminum standoffs
Boom Material: Molded carbon fiber epoxy composite Boom strut material: Carbon fiber with metal ends Tail Fin: Carbon fiber
Rotor to pinion: 9:1 (23T purchased / 21T pinion included)
Sand down any edges on the carbon fiber frame where electronics wires may pass over to ensure no cuts
Take apart the head and tail assemblies and apply recommended grease and Loctite
The Goblin series of helicopters work best with tight belt tension
Center cyclic servos before installing on the servo mounts as you cannot get to the servo horns once installed
Before a new helicopter build there are a few steps I do to prepare. I always lay out all the parts and bags on a separate table so I don’t clutter my main build area or risk mixing parts up. I also lay out the tools; put some Loctite in a water bottle cap, as well as a cap full of rubbing alcohol to degrease all the screws. Having a towel on the table will ensure that important screws or washers don’t roll away. Nothing is as aggravating as crawling around on your hands and knees with a flashlight in your mouth to find that one nut or screw you need to finish a build. I speak from past experience guys … not fun!
SAB includes a personal serial number with each kit and they recommend that you go to their website, www.goblin-helicopters.com and register your SAB kit so they can notify you of any possible upgrades or improvements that may come at a later date.
The frame is assembled by securing the two 2mm carbon fiber side frames to the plastic bottom plate and CNC ESC mount using the machine screws and chrome washers.
Unlike my other Goblin models I’ve built, the 570 uses the strong competition skid braces that slide into the bottom plate just like the original 570. The landing gear mounting brackets do not require bolts to be installed. The brackets act as a sacrificial breakaway point during a crash, preserving the frame sides and other important parts. The skids bolt onto the mounts and vinyl stickers are included to dress them up to match the canopy. The Goblin 570 features a quick removable battery tray system as seen on the Goblin 500, 380 and original 570. It makes battery changes extremely quick and easy to get you back in the air fast.
The next chapter is the transmission part of the build, yes I said transmission. The Goblin series of helicopters are not like your traditional style gear train design. SAB uses a unique design where the motor pulley drives a belt; the belt turns a shaft with a helical gear that then drives the main shaft. Not only is it efficient, but it is quiet as well. Don’t worry about stripping main gears or breaking a drive belt. The 570 is equipped with a stronger main gear and Gates GT3 drive belt.
The Goblin 570 uses the HPS 3 head design which 8 stands for “High Precision System”. This rotor head has been developed in order to increase the usable rotor RPM range without having to change the rigidity of the dampening system. Furthermore, this solution allows an optimal control of the geometry even when large amounts of torque are introduced into the system. The HPS 3 head also allows for a lower range of headspeeds where DFC style heads are rigid and do not like lower headspeeds and tend to bobble. The HPS head is mounted onto the 10mm high strength steel main shaft. The ball links are bidirectional so you do not have to pop the links off to adjust the length when tracking the blades. A nice fea- ture considering that popping the ball links on and off will wear out your links over time.
Depending on the servos you use SAB has offered a few different ways to mount the ser- vos to allow the most ideal servo geometry. Always plug in your servos and center the servo arms before you install the servos onto the transmission servo mount plate. It is not impossible but hard to reach the servo horn screws once installed.
The swashplate does not come built so you will need to Loctite and install all of the swash balls. Once you have the swash assembled you can install the swash and head onto the main shaft. All of the links fit perfectly with zero slop or binding. The lengths of each linkage given in the manual were almost spot on. A turn or two was all that was required to tune the head and get everything centered. I really like the fact that I can adjust blade tracking without disconnecting the plastic ball links. The motor mount has self tensioning springs to ensure constant pressure on the belt. Once the belt is installed spin the motor by hand to ensure the drive belt has proper vertical alignment on the gear. If it favors high or low adjust the motor pinion to split the difference.
Tail assembly starts with building the tail hub assembly, pitch slider, bell crank lever, and tail case. Just like the bigger competition models, the Goblin 570 uses a dampened tail system to ensure smooth operation. Make sure you apply grease and Loctite to the proper parts. The tolerances were perfect with zero play and everything moved extremely smooth. The Goblins have a unique design where the tail side plate and vertical fin make up the tail case. They are held together by tail case spacers and adjustable machine screws and lock washers which allow the case to slide back and forth to adjust main belt tension. After that, the boom is installed and the model is pretty much ready to go.
SAB has widened the inside shape of the canopy to assist installing and removing the canopy without rubbing on the links or causing unnecessary stress on the fiberglass. The airbrushing and quality of the new carbon color scheme paint are typical of Canomod’s high quality canopies which feature beautiful lines and vivid yellow colors. Canopy saver rub- ber gasket is also included to protect the canopy edges from scuffing.
The cool thing with the Goblin 570 is that you have the choice of running either a 6S or 12S power system with a range of different size flight packs. For my testing I used Pulse Ultra 4500mAh, 5000mAh and 5500mAh 45C packs. My recommendation is lean towards the 5000-5500mAh packs if you want to stretch out flight times. If you plan on just sport flying the 4500mAh will give you about a four minute flight time at 2000 rpm. You could even get more if you optimized your power system to run at a lower headspeed. The 5500mAh packs will easily give you a six minute flight at 1800 rpm. For hard 3D stick to the 5000mAh packs for great power to weight ratio giving you a five minute flight time. I really enjoy the constant power and reliability I get out of the Pulse Ultra packs. All size batteries easily fit on the included slide out locking battery tray. If you only have one battery tray swapping out flight packs is as easy as un- strapping the SAB Velcro strap and throwing another pack on. I keep six packs on trays and three more packs charged and ready to swap if it’s a busy day of flying or testing.
BLACKLINE 540MM ROTOR BLADES
SAB’s Blackline blades are the prime example of SAB’s continued commit- ment to improve the quality and performance of their products. All of SAB’s rotor blades are created by SAB engineers and designers with the support and collaboration of international top pilots. Each blade is designed and tuned to handle the demands of any flybarless control system. SAB installed a steel safety wire alongside the leading edge of the blade in case of a crash to protect both pilot and spectators. Blades are also made with a double layer of unidirectional carbon fiber.
SAB Blackline edition blades are available in three different versions 1D, 2D and 3D to accommodate pilot’s different flying styles. The 1D blades were designed for speed flight to obtain maximum stability in fast forward flight regardless of the flybarless control system being used. 2D blades were developed for sport fliers in mind providing precise aerobatic flying. The blades center of gravity and total weight is optimized to reach the best compromise between stability and maneuverability. They also offer a special class of 2D blades designed specifically for F3C pilots. The 570 kit comes with 540mm 3D version of Blackline blades which were designed to optimize agility and maneuverability during hard 3D flight. The total weight and center of gravity were optimized in order to improve flybarless control system stability and setup. SAB gives you the choice to customize the color of your Blackline blades with silver, white, red, green, yellow and orange.
1. HPS 3 Head (High Precision Head System) 2. SAB 540mm Blackline 3D blades
3. Two-stage belt transmission
4. New swashplate design
5. Standard size servos
6. CNC main gear
7. Competition style skids 8. Dampened tail system 9. SAB 104mm tail blades
10. Sliding battery tray with locking system 11. Ultra strong carbon fiber tail boom
12. Extra electronics mounting plate
IN THE AIR
After a quick circuit around the field to run the NEO flybarless system through its initial setup test flight and adjust tail gain settings in all flight modes, it was time to run the Goblin 570 KSE through its 3D paces. The 570 tracked per- fectly through the corners, with noticeably higher control precision. Its cyclic response was much quicker than my two-blade setup and I lowered the head gains down to 40 in all banks. Stationary flips and rolls are fast and stable, with no noticeable wobbles and tic-tocs were crisp and precise. The bright yellow Canomod canopy was extremely easy to see in all orientations and light.
For sport flying the 570 really flies well at 1800 rpm with zero bobble and extends your flight time. I tend to fly in Bank 2 at 2000 rpm to practice my collective manage- ment and not sacrifice my flight times. I found that 2000 rpm gives me a long flight time and still gives me plenty of perfor- mance to fly low headspeed 3D. If I want to really show off the Goblin 570’s abilities I can crank her up to 2300 in Bank 3 for extreme fast forward flying and hard 3D.
Flight mode Throttle RPM
Normal ……………………………….Governed ……………………….. 1800
Stunt 1………………………………..Governed ……………………….. 2000
Stunt 2………………………………..Governed ……………………….. 2300
THE LAST WORD
For a midsized 3D machine, the SAB Goblin 570 KSE provides the stability of larger helicopters, while maintaining portability and economical operation of a smaller helicopter. These benefits make the Goblin 570 KSE a top choice for the weekend fliers, as well as a practice machine for the serious competition pilots. The past few months of flying my 570 KSE I can honestly say I will never go back to flying a two bladed Goblin again. The reasons are many, but include feel, agility, cyclic response with maintenance free flight after flight. To say that I’m pleased with this helicopter would be a huge under statement. You get the best of a single pack machine with the added benefits of its bigger competition counterparts. Not only do you get numerous new features, but you have someone as kind and humble as Kyle Stacy himself backing the product 110%!
For more pictures and video you can visit my helicopter Facebook page or website. www.3DandScaleRCHelicopters.com Also be sure to check the Radio Control Heli Pilot website for build and flight videos. www.helipilotonline.com. See you guys at the field!
CASTLE CREATIONS castlecreations.com, (913) 390-6939
MIKADO mikadousa.com, (844) 464-5236
MKS SERVO USA mksservosusa.com, (949) 514-5866
PULSE BATTERIES pulsebattery.com, (877) 439-4354
SAB GOBLIN goblin-helicopter.com, (877) 439-4354
SCORPION POWER SYSTEM scorpionsystem.com