Goblin Black Thunder 700 T-Line

Goblin Black Thunder 700 T-Line

It has been almost one year since SAB released the Goblin Black Thunder 650. After requests from the pilots SAB stepped up to their latest 700 size model, the Black Thunder 700 Green Version but in reality this was just an upgrade from 650mm to 700mm so SAB Heli Division decided to do a complete new 700 sized machine the Black Thunder T-Line, (T-Line is synonym of TOP SAB technology). In the T Line department SAB has the new version of the popular Black Thunder with input from T. The new collaboration focuses on decreasing the overall weight of this 700 class flying machine.

SAB has taken extra measures to reduce the weight from places like the canopy, main frame, and tail boom. They also included a few specific changes to the bird with a different color scheme, a quick battery tray release, and quick tail fin replacement. The new kit will include a set of the T Line SAB rotor blades in your choice of 690s or 710s. At the moment the Black Thunder and the Black Nitro (which we reviewed in previous issues) is one of the best selling models in the SAB Goblin range and in this review we want to show you in detail this super sales.

BEGINNING:
SAB presented their first prototype at the F3C World Championships in Brescia, Italy (2011). But it was really unveiled two months after at the famous Alpine Heli Smackdown (Switzerland). There all the pilots could see a helicopter, which was totally different from what we have ever seen, it was called the Goblin 700, a helicopter from the famous blades manufacturer SAB.

Until then all the pilots thought that „acrobatic scale fuselages“ were destined for F3C competition. King of 3D, Tareq Alsaadi was in that time sponsored pilot with Outrage. SAB prepared a Goblin 700 to be flown by Tareq so he could show that this helicopter was born to perform extreme 3D. They did the test flight in front of a lot of public and he just performed an amazing flight! From that moment onwards Goblin was a revolution! That heli captivated all the pilots in the world and became a world wide super sale. After five years SAB Goblin launched a full range of model going from a Goblin 380 up to the massive Goblin 770 and for the F3C pilots the great Urukay. But now its time to replace their Goblin 700 Competition with the new Black Thunder 700. The Italian owners of Goblin Stefano Baiardi and Enrico Bernabei marked a before and after in the design of RC helicopters.

THE MODEL:
Although the real name of this helicopter is Goblin, its nicknamed with Evil… It’s a helicopter with very peculiar flying characteristics. It is agile, fast, and powerful. The flying style of this helicopter is very different from the rest. No doubt that is a very special helicopter.

Thanks to its design, the performance level is very high. It uses a belt drive system that efficiently transfers engine power to the rotor. The motor pinion uses a belt that moves a 60T pulley. This pulley has mounted below one transmission pulley that drives the tail-belt. At the top of the pulley we have the steel helical pinion that attacks the main gear, which eventually moves the rotorhead. This system is patented by the company of SAB.

The servos are mounted horizontally around the 120° CCPM swashplate. The servos are connected directly to swashplate with a linkage rod. This forms a very rigid and accurate assembly. This method allows the maximum lowest center of gravity, and increase performance to the max.

The important part of the mechanism is the central part consisting of a aluminium frame tray, main servo mount and motor mount. Here we install the servos, motor, gears and pulleys. This frame tray is easily removable for maintenance.

The tail uses a simple belt drive system with a special tail belt idler. Designed to work at 12S (44.4V). Current Brushless motors are very powerful, and it is important to take advantage of that energy. With double belt system, the Goblin Black Thunder handles this energy very efficiently.

The Italian design is unique. Visually its very attractive as the canopy binds with the tail boom made fully of carbon fiber, the new T-line comes in a Red, Black and Silver colour scheme which looks really nice and has very good visibility in the sky. Its streamlined design gives the Goblin incredible speed capabilities. The tail system eliminates vibrations of the tail rotor at high rpm. It is strong and lightweight.

The new HPS2 (High Precision Head System) rotor head of the Black Thunder comes with matte black components. This new head is lighter than Standard Goblin 700 Head. More details on this rotor head later.

SAB is known worldwide for manufacturing RC carbon fiber blades. The Goblin had to include them. In the box we find the whole newly designed T-Line blades. SAB gives the pilot the option to choose the kit with 690mm (Ref. SG715) or 710mm (Ref. SG716) Thunderbolt T-Line blades and 115mm tail blades in Black, white and red colours.

They used mainly carbon fiber parts for the construction. Getting a low weight heli, was a target of SAB.

T-LINE BLADES:
The T line is designed to enhance the torsional performances of the already excellent Thunderbolt series. Performances in torsion are improved thanks to the use of high-carbon DynoTech modulus; the result is an extremely precise blade, ready to any change in command.
The Carbon DynoTech also gives a modern and attractive look to this new series, making the T line unique and unmistakable.

The difference between choosing for 690mm or 710mm depends on your flying style, if you are looking for a more precise kind of flying you definitely should choose the 710mm blades but if you are more a smack kind of pilot then go for the 690mm size. Keep in mind if you are running the 710mm that you need to lower the head speed compared to 690mm. We tested and the best head speed for 710mm is 2050RPM and for 690mm 2150RPM up to 2250RPM depending what you need.

UNBOXING:
The kit is presented in a professional manner. When we opened the box, we find high quality CNC aluminium and carbon fiber parts. The CNC parts come protected in foam trays to avoid scratching. The rest of the parts some all well marked in plastic. All are numbered and correspond to the assembly procedure manual.

The manual is visually appealing, it’s printed in full colour. Inside we can find the different ratios and configurations suggestions. It is very important to choose the correct ratio that maximizes efficiency depending on the motor, pinion and rpms we want to fly.

SAB also included a useful sheet with points to be reviewed during maintenance. Includes a full list of spare parts with images, which is very useful when we need to order any part.

The goblin is a helicopter which needs regular maintenance and does not only need to checked after a crash. Therefor SAB has included a sheet that explains the important parts to check.

MAIN FRAME:
One of the new highlights compared to the previous Black Thunder is the new frame used on the Black Thunder T-Line. SAB decided to go for a extra light main frame using 1.5mm using real carbon fiber frames. At a first glance it looks weak, but after mounting all the inside parts its really reinforced. The second highlight is the new quick release battery tray that is mounted the lower part and has a special carbon tray to install the ESC. The quick release battery tray is anchored to the frame. The kit comes with two extra battery trays to assemble convenient battery packs which makes it possible to change the battery packs really fast and secure them in place. The landing gear on the Black Thunder is one of the points that characterize this Goblin because it comes with a Speed look landing gear like its smaller brother the Goblin 500 Sport. Goblin offers an additional carbon fiber landing gear if you would like to change it. We decided to use the optional landing gear since we not always fly on flat surfaces which makes it easier to land. The original landing gear that comes with the kit is composed of two carbon fiber landing gear plates which are mounted directly on aluminium landing gear support brackets on the frame.

Its very well explained in the manual were to put which glue or locktite but we always recommend those screws threaded into metal to apply a little lock tite to the screws. It is very important to use it well to prevent stripped bolt heads or broken screws. Its sufficient to apply a little on the tip of the screw (aprox.1mm).

Once you have installed this we start with the main structure of the frame. The Goblin comes with a central CNC aluminium frame tray. This structure comes standard with two bearings mounted. On this tray we need to mount the full transmission system on a later stage. Now we mount the main servo mount onto the frame tray with four special aluminium spacers and we mount the servos the mount. The servo support is fully made of CNC aluminium and comes with two bearings though which the 12mm main shaft passes, and on through the other one a 10mm secondary shaft.

Some parts are factory pre-assembled. I always check everything to ensure the correct assembly and if threadlock is applied. To join the frame tray and servo mount it uses 4 aluminium spacers. The carbon fiber anti rotation guide is mounted to the servo tray. The 68T main drive gear is helical. The tail belt idler is mounted on the lower part of the frame tray. The tension of the tail belt idler is adjusted by turning the belt idler that tensions a spring. The SAB manuals one of the best I’ve seen with very clear and detailed drawings. The manual indicates us that we have to grease the one way bearing of the 60T pulley and on the main gear, we recommend to use Dryfluid Heli and Gear Lube here, in our opinion its one of the best grease on the market. The wiring is a very important part on this frame, you should spend time to prevent rubbing of the cables on the on transmissions and frame edges. The motor mount is located in the front of the chassis. Damping springs are used. Depending on which motor we mount we have to take into consideration the length of the motor shaft, the manual gives you the ideal length so its easy to find the appropriate shaft or shorten the one already on the motor. If it is too long you are not able to place the battery protection plate and may rub on the batteries, and this is a big problem. The manual advises cutting the shaft with a Dremmel to the right size. The kit comes with a 21T pinion. In my case I mounted the 24T pinion to achieve the 8.9:1 ratio and get 2050RPM with 710mm blades and 2150 RPM with 690mm blades. The motor we use is the Kontronik Pyro 800-48. This pinion does not attack directly the main gear but uses a belt drive system. Since the Pyro 800-48 comes with a 8mm motor shaft its not needed to use the third bearing support as with motors with a 6mm motor shaft.

MATT BLACK HPS ROTOR HEAD:
The Goblin Black Thunder comes standard with the matt black HPS rotor head. This head has been developed in order to increase the usable rotor RPM range without having to change the rigidity of the dampening system. The new head is developed specially to limit the teetering effect of the spindle by means of dampening achieved by a special techno polymer material. The maximum teetering amount can be adjusted based on the amount of play shown in figure ¨A¨ of the drawing. The O-ring is necessary to create a radial and axial preload. The preload can be kept relatively low, thanks to the mechanical locking properties of the dampeners.

Furthermore the spindle can only move vertically thanks to the elongated hole shown in figure ¨B¨ of the drawing. This solution allows an optimal control of the geometry even when large amounts of torque are introduced into the system.

The HPS rotor comes pre assembled in a box. The manual explains very well where we need to apply thread lock and grease. I personally like this rotor system much more then the DFC version, Maintenance is easier, and cheaper during crashes. In flight the DFC rotor head are overly aggressive and have very quick response due to its low center of gravity and stiffness.

The rotor head consists of a center hub, blade grip arms, radius arms, linkage rods and dampers.

Dampers used are made of Delrin and together with a O-ring are mounted inside the center Hub. Each blade grip has two radial bearings and one thrust bearing. In kit includes several washers to control the play of the spindle shaft. In the manual recommends using one 1mm washer and one 0.2mm washer on each side. If the blade grip feel very rigid we need to removed the 0.2mm washers. Its recommended to check for axial play of the spindle after the first flights. If the play has changed you can add one or two 0.2mm washers.

The linkage system used is with turnbuckles. In the middle of the linkage we can find a small hole through which you can pass a 1.5mm hex driver to accurately adjust 0 pitch on the head.

The swashplate on the Goblin Black Thunder comes also in a matt black colour to match the rotorhead.

BOOM & TAIL:
The tail is one of the characteristic items of a Goblin. The boom has nothing to do with a traditional tail boom. SAB manufactured a oversized fully carbon fiber tail boom which comes factory painted to continue the colours of the canopy. It is rigid enough so no need for tail boom supports. Another curiosity is the way it anchors into the frame with a aluminium guide into 2 plastic nylon screws. The kit includes a special plastic tool for this. The goal of this anchoring system is that when you crash the screws break and saves the tail.

The tail servo is mounted upside down on the lower part on the boom. More or less in the lower part of the center of the boom we need to mount the tail push rod guide. The tail push rod is made carbon fiber. It is important to protect the tail servo cable and use some servo braid to avoid the cable can be damaged by sharp edges on the carbon fiber.

Now a days we are very used to see all the helicopters using torque tube drive system but the Goblin uses tail belt drive. The overall design is very simple and easy to assemble with very few parts. Most of the parts like the locking reinforcements and tail servo locks come pre-assembled by the factory in the box. Although you need to check everything and ensure correct installation. The tail rotor assembly comes also entirely in matt black aluminium. It uses a traditional double tail pitch slider. The third highlight of this new Black Thunder is the newly designed quick tail fin replacement system. The tail box is formed on one side by a carbon fiber case side and on the other side a matt black aluminium case side. To mount the whole tail case its done by 4 aluminium spacers. The tail fin is now a separate part so we are able to change the tail fin without taking the tension of the tail belt. Very convenient and quick to replace when we go a little to low! The tail uses a 26T pulley on the tail.

SETUP:
The basic setup of this model used in this review is the following with a V-Bar Control and a V-Bar NEO flybarless system.

Since this was not the first Goblin Black Thunder 700 I have ever build I copied the settings from my other Black Thunder to this new model as a starting point although I knew it needed little tweaking since it comes with the new T-Line blades and its lighter then the previous Black Thunder. We tested various settings and this is how we liked it the most. On the main rotor settings we use an Expo of 15, Style is set to 95, Rate++ to 124 and a head gain of 51. For the tail we use expo at 15, Rate++ at 124 and tail gain is set to 45. The settings are always a personal choice but this is the way we liked the model the best. We used a Kontronik Kosmik 200A so we can set 3 head speeds using straight linear throttle curves and programming the Kosmik with Mode 4. The correct ratio as previous explained with a 24T pinion and a 480KV motor is 8.9:1. With this setup we can reach a maximum head speed without governor overturn of approx. 2150RPM, this was the range I wanted to fly this helicopter.

The throttle curve is set the following way, we used the straight linear throttle curves in mode 4 on the Kosmik speed controller. The motor has 480KV and we used a 12S setup with SAB Lipo 4800mah 60C Competition packs and the 24T pinion.

THROTTLE CURVE

Low 25% 50% 75% High
Normal 65% 65% 65% 65% 65%
Idle up 1 78% 78% 78% 78% 78%
Idle up 2 80% 80% 80% 80% 80%


Flight mode: Aprox. RPMS 690mm:
Normal 1950rpm
Idle Up 1 2150rpm
Idle Up 2 2250rpm


Pitch curve have been set in all flying modes to -13 at low stick, 0 at mid stick and +13 at high stick like recommended in the manual.

TEST FLIGHT
Initially we programmed in normal flying mode 1950 rpm. During hovering the Goblin Black Thunder 700 behaved very stable. With these RPM´s the behaviour of the helicopter is very smooth and predictable.

The Goblin is a heli that needs to go at higher rpms so we activated idle up 1 raising the head speed to about 2150rpm. I started doing some fast forward flying and the heli traced a perfect straight line without any strange tendencies. I really liked the smooth sound coming of this heli. It is noticeable that this heli can reach very high speeds thanks to its aerodynamic shape.

Thanks to its design, it has fantastic visibility in flight in all directions. We started with some smooth manoeuvres like hurricanes, pie-dishes, kaos, backwards flying… and the helicopter held really well during all these manoeuvres and was very accurate and powerful. It was time to activate idle up 2 raising the head speed to the maximum possible rpm with this ratio, 2250rpm. The sound changed completely, now it really started roaring with perfect flight behaviour at all time!

The cyclic response is perfect in my opinion. The flight characteristics offered by the rotor HPS are very good with a different feeling then flying with the traditional DFC rotor heads on the Goblin in a similar size. In my opinion the HPS rotor head is the perfect mid way between a aggressive and smooth, precise flight. The Goblin Black Thunder is extremely agile and fast with a very aggressive flying style. The tail performs well in all kinds of manoeuvres with Piro and reverses. The dynamics with the V-Bar Neo is perfect. Although nowadays the torque tube is the most widely used in helicopters, I must say that the belt works pretty well.

The kit includes a sheet named (important tips for proper assembly). Here SAB explains some of the key points of the helicopter where you should pay attention. Although helicopters are prepared today for more radical 3D all have wear and require maintenance. Sounds like a good idea that SAB includes a sheet with Tips & Tricks.

VERDICT
The mechanics are very special and different from other helicopters on the market. Apparently it seems that the mechanics are very simple and quick to assemble. But it’s not true, they are quite complex and need time to do it right. After a few flights you need to check the belt tension. The helicopter is designed with quality and excellent flight performance. Its visibility in the sky is very good thanks to its fuselage and fluorescent colours. It is simply a helicopter that demands now a days trends at all the flying fields. SAB offers the option of modifying the ratio depending on our flying style. At low rpm is a very docile model. But if we go up the rpm on Goblin Black Thunder has a terrifying flight that takes hold of you.

SAB GOBLIN BLACK THUNDER

General Specifications:

  • Main rotor diameter: 1548 mm with 690 mm size blades
  • Main rotor diameter: 1588 mm with 710 mm size blades
  • Tail rotor diameter: 305 mm with 115 mm size tail blades
  • Approximate weight RTF: 5300 grams
  • Cyclic Servos: Standard size (40mm)
  • Tail Servo: Standard size (40mm)
  • Typical battery setup: 12S – 5000mAh, (from 4500 to 5200)
  • Typical ESC setup: 120A/160A ESC
  • Typical Motor setup: 480/560KV KV

Manufacturer: SAB GOBLIN
Web: www.goblin-helicopters.com

Kit Includes:

  • 690 mm or 710mm ThunderBolt T-Line main blades
  • 115 mm ThunderBolt tail blades
  • Motor Pulley 21T
  • 2 Sets Battery Tray

Equipment used…

Blades: SAB Thunderbolt T-Line 710mm & 690mm
Flybarless: V-Bar NEO
Cyclic servo: BK Servos BLS7002HV
Tail servo: BK Servos DS-7006HV
Battery: 2x SAB Lipo 4800mAh 60C Competition
Motor: Kontronik Pyro 800-48
ESC: Kontronik Kosmik 200Ah