Kraken 700 And 580 Helicopters

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Written by James Wang
Tips and setup advice
As seen in the June 2021 issue of Model Aviation.

In the December 2020 issue of Model Aviation, I explored the history of the original SAB Goblin helicopters. In this article, I want to examine the SAB Kraken 700, the Kraken 580, and the Kraken 580 Nitro. Kraken helicopters are the flagship helicopters from SAB, and quite a few innovative features have been introduced since the company’s previous generation of Goblin helicopters.

Features include a refined main rotor blade grip design, a sealed transmission system to keep dust out, separated upper and lower canopy shells, a plastic pipe to keep the ESC wires neatly tucked away, a stronger tailboom mounting arrangement, a different tail rotor pitch slider, and a lighter tail gearbox design.

the kraken 700 is the 30th sab helicopter
01. The Kraken 700 is the 30th SAB helicopter by Italian designer Enrico Bernabei.
the kraken 700 is the 30th sab helicopter
02. The Kraken’s mechanics are very different from the previous generation of SAB Goblins. Notice the plastic pipe for routing the signal wires from the ESC to the receiver or FBL gyro.
the kraken 580 is a smaller replica of the kraken 700
03. The Kraken 580 is a smaller replica of the Kraken 700. The design is modular and lower body panels improve visibility.
the kraken 580 nitro uses the same enclosed transmission system
04. The Kraken 580 Nitro uses the same enclosed-transmission system, rotor and controls, and tail section.

The Kraken 700 is the 30th model helicopter design from proliferate Italian designer Enrico Bernabei. Looking closely at the canopy, you can see the number 30 painted in silver over the black windshield area.

In a conversation several years ago, while on a tour to see how full-scale helicopter transmissions are made, Enrico mentioned that it would be great to have a sealed transmission for models.

The original SAB Goblin design that was introduced in 2011 has a two-stage gear reduction system: the electric motor drives the first-stage gear reduction through a wide-tooth belt then the second-stage gear reduction is through a metal pinion gear driving a Delrin main gear. The advantage to this is that it helps reduce the width of the drive system. Furthermore, the tail rotor can be driven by the second stage because it is already at a reduced rpm from the motor.

With the Kraken design, Enrico has kept the belt-drive first-stage gear, but he enclosed the second-stage gear reduction completely inside an aluminum transmission housing that is sealed with lubricant.

The Kraken 700 has been on the market for nearly two years and has proven to be extremely reliable and effective. The sealed transmission comes preassembled and packed with grease from the factory.

After a flight, the housing is slightly warm because the grease inside is doing its job swishing and lubricating the gears. So far, I have not seen a leak from my Kraken 700 or Kraken 580. No other model helicopters on the market use such a unique closed-transmission system.

With the success of the red Kraken 700 that was introduced in 2019, SAB introduced two yellow Kraken 700 kits in 2020 with a choice of two- or three-blade main rotors, followed by a medium-size Kraken 580 electric and a Kraken 580 Nitro in late 2020. The Kraken 580 is Enrico’s 33rd helicopter design and the Kraken 580 Nitro is the 34th.

The Kraken 700 and 580s take it up one notch with updated main rotor and tail rotor designs and vertically mounted cyclic servos. In a hover, the Krakens rest solidly in the air as though they are held by a pair of virtual vise grips. In forward flight, they track as though they are on rails.

When a stick command is prescribed, they respond precisely with no hesitation. The combination of the Kraken mechanics and use a high-quality flybarless (FBL) gyro makes a pilot appreciate how responsive and precise a modern RC helicopter can be. The Krakens are among the most reliable mechanics on the market now. To bring out their peak performance, use the best electronics, powerplant, and the best flight batteries you can afford.

the electric powered version accelerates faster
05. The electric-powered version accelerates faster, but the nitro version sounds good and carries a presence with its sound and smoke.

Components Required for Krakens

I recommend using a high-end 520 to 530 Kv motor with at least 4,000 watts of continuous power capability for the Kraken 700. For the Kraken 580, choose a 4025-size 500 to 560 Kv motor if using a 12S battery, or a 4025-size 1,100 to 1,320 Kv motor if using a 6S battery.

The following are the brands I have used and have found them to be extremely reliable and high performing. For motors, the XNOVA Lightning or Temptation Series, the Scorpion Competition Series, or Kontronik will all work well.

For ESCs, use at least a 160- to 200-amp-rated ESC for the Kraken 700, and 120 amps (high voltage for 12S or low voltage for 6S) for the Kraken 580. The following ESC models all work well on the Krakens: Kontronik Kosmic, Castle Creations Phoenix Edge, HOBBYWING Platinum, Scorpion Tribunus, and the new Black Edition or Saphir Blue ESC from YGE in Germany.

For FBL gyros, try the Mikado Neo, iKON2, MICROBEAST, or bavarianDEMON. Always use metal-gear servos for FBL helicopters. For the Kraken 700, there are many high-quality, standard-size, digital, high-voltage (HV), metal-gear, double ball-bearing-supported servos on the market. Choose a cyclic servo with at least 200 inch-ounce of torque.

The Kraken 580 kits come with servo mounts for mini servos. Servo mounts for standard servos are sold separately. The Kraken 580 and Kraken 580 Nitro use mini servos because modern, high-end mini servos are as powerful or more so than older standard-size servos.

There are many strong, standard-size digital servos available on the market, but fewer choices for strong digital, HV mini servos for cyclic control. I have used MKS HV9767, BK DS-5001HV, GDW DS590MG brushless, Gaui DS303 brushless, and KST DS589HV mini servos. They are excellent and capable of running at 7.4 to 8.4 volts, producing more than 120 inch-ounce of torque, and have metal gears. I recommend any of them. For tail rotor control, the Kraken 580 only uses a standard-size servo.

For high-performance helicopters such as the Kraken 700 and 580s, I recommend HV (7.4- to 8.4-volt) servos because they provide extra torque and speed. You must decide whether to power the servos by the BEC from the ESC, use an external BEC, or simply use a separate 2S 1,800 mAh LiPo battery.

Using a separate 2S battery to directly power the HV servos, gyro, and receiver is the most reliable way, but that’s an extra battery to charge and extra weight. When powering directly by a 2S LiPo battery, please make sure that the servos are HV type, otherwise, the servos will burn out. Most non-HV type servos can only handle up to 6 volts; however, most receivers and FBL gyros can handle up to 8.4 volts.

If using the BEC from the ESC, be sure to do some bench-testing by removing the main and tail rotor blades and pumping the transmitter collective stick rapidly nonstop to see if the servos will suddenly glitch or stop. If the servos hesitate, it implies that the BEC is not able to supply the current required for your particular servos.

For example, when I did the previous exercise using a HOBBYWING 130-amp HV ESC with a built-in, 10-amp BEC and three KST cyclic servos, the KST servos did not glitch. Repeating this experiment on the bench with three Align BL800H brushless servos, three BK BLS8002HV brushless servos, or three Futaba BLS172SV servos, the servos would temporarily pulse and start again. These high-torque servos draw more current than the BEC can supply, so I used a 2S LiPo battery to directly power these servos.

the kraken 580 rotor head shown here
06. The Kraken 580 rotor head shown here is of the same design as the Kraken 700. How the blade pitch arm is attached to the blade grip is different from the Goblin helis.
the xnova lightning series 4025 560 motor
07. The XNOVA Lightning Series 4025-560 motor is a powerhouse for the Kraken 580 running on a 12S battery. The servo mounts are designed for mini digital HV servos with metal gears.

Engines for the Kraken 580 Nitro

Before electric helicopters became powerful and popular a decade ago, two-stroke nitro engines dominated the RC helicopter scene from 1970 to 2010. From 1970 to 2000, the most popular class of helicopters was powered by 60-size (0.6 cu. in. or 10cc displacement) engines.

From 1976 to 1980, we saw some new helicopters powered by 40-size engines, but their performance was mediocre. Gorham Model Products was the first company to make 50-size helicopters popular when it introduced the Cobra in 1984. From 1985 to 2005, 30-size nitro helicopters dominated the market and helped introduce many people to the wonderful world of RC helicopters. The Hirobo Shuttle, Kyosho Concept 30, and Thunder Tiger Raptor 30 made RC helicopter flying affordable and fun.

The 50-size helicopters came back in 2003 because Thunder Tiger stretched its successful Raptor 30 into a Raptor 50. The 50-size nitro helis became popular because they were less expensive than 60- and 90-size nitro helicopters.

The compact, 50-size helicopters use the same electronic components as 30-size helicopters and have better power-to-weight ratio for performing 3D aerobatics. What made the 50-size heli a huge success was a wide choice of high-performance, reliable, two-stroke engines that ran on 15% to 30% nitro fuel.

O.S. Engines introduced the O.S. 50 SX-H then the O.S. 55HZ engines. YS Engines introduced its YS 55SR engine and recently the 60SR. Thunder Tiger introduced the TT50H followed by a more powerful Redline 53H engine, and Novarossi introduced the powerful R57HR3DS Italian engine.

Today, the most popular 50-size helicopter engines are from O.S. and YS. These Japanese engines have been refined with 40-plus years of model helicopter engine design and manufacturing experiences. They are reliable and user-friendly.

The manufacturing tolerance is consistent. I have used many O.S. 50-size engines, and every one of them runs well. They start right up on the first crank. These engines are excellent choices for the Kraken 580.

I am happy that SAB decided to introduce a nitro version for its Kraken 580 because it drinks less fuel than 90-size nitro helicopters. A gallon of 30% nitro fuel is roughly $30 and only good for eight flights on a 90-size helicopter with a 16-ounce fuel tank, but a gallon can yield approximately 12 flights on a 50-size helicopter. The flight time for an electric Kraken 580 is 4 minutes long when flying 3D, and the Kraken 580 Nitro’s time is 7 to 8 minutes.

The O.S. 50 SX-H Hyper Ringed Competition Helicopter engine retails for $229. It has been in production for 15 years and is bug free. The displacement is 0.50 cu. in. (8.17cc), it weighs 14.3 ounces, and develops 1.9 hp at 17,000 rpm. The two-needle-design 60LH carburetor is easy to set. The piston bore (diameter) is 0.866 inches (22mm) and its vertical stroke is 0.847 inches (21.5mm).

Because the stroke is smaller than the bore, it is called a short-stroke engine and is good for high revving. Older, long-stroke (stroke is larger than the bore) engines are great for generating torque and tend to vibrate more at a higher rpm.

The O.S. 50 SX-H is well-suited for beginner to intermediate pilots. This engine develops its maximum power at 16,000 to 16,500 rpm. The Kraken’s engine-to-main-rotor-gear ratio is 7.98. This translates to a best rotor rpm of 2,050 for 3D flying.

This desired rotor speed can be achieved by the classic method of trial-and-error tuning of throttle curves, by setting the rpm using an engine governor such as a Futaba GV-1, or using the engine governor feature in some FBL gyros.

I recommend the O.S. 55 HZ-H Hyper Ringed Competition engine at $299. It has a 0.55 cu. in. (8.93cc) displacement and is still the top-of-the-line 50-size engine from O.S. It has a usable range from 2,000 to 17,000, and its best performance is at 16,500 to 17,000 rpm. You can bump up the rotor speed to 2,100 rpm to achieve more powerful collective and cyclic controls.

The same O.S. 55 HZ engine is also available with a regulated or metered fuel-feed carburetor system. Called the O.S. 55 HZ-R DRS, it retails for $399. DRS stands for Demand Regulator System and it pressurizes the fuel tank to force fuel to flow to the carburetor rather than relying on the carburetor to draw fuel.

batteries are attached to a sliding tray for easy loading
08. Batteries are attached to a sliding tray for easy loading. A 12S 5,000 mAh battery is used for the 700, and either a 6S 5,000 mAh or a 12S 3,000 to 3,300 mAh battery for the Kraken 580.
a standard size tail servo is used on the kraken 580
09. A standard-size tail servo is used on the Kraken 580. The servo is mounted underneath the tailboom.

The pressure is supplied from a nipple in the engine’s crankcase backplate, and a one-way valve is used to maintain the pressure inside the fuel tank. The regulator on the carburetor picks up the negative pressure created in the venturi and supplies fuel consistently according to the carburetor opening. The result is a consistent engine run from full tank to empty tank, regardless of helicopter attitude. This engine has a practical rpm of 2,000 to 20,000. I really like this engine. Its peak power is roughly 17,000 to 19,000 rpm. The engine is only slightly heavier at 15.1 ounces (429 grams).

YS was the Japanese engine company that made the pressurized regulator system popular 30 years ago, and all YS engines use it. Without a pressurized regulator system, model engines tend to run rich when the tank is nearly full, and then run lean when the tank is nearly empty. YS engines are reliable. In January 2021, CK Aero became the new distributor and service center for YS Engines in the US. YS states that its engines can be used for many years by overhauling them with serviceable parts such as bearings and piston rings.

All of these engines have identical mounting-bolt patterns and fit the Kraken 580 Nitro perfectly. The companies (except YS) also make their own mufflers. I recommend using O.S. #8, Enya #3, or Enya #4 glow plugs, and only using helicopter fuel blended with synthetic lubricants and 20% to 30% nitromethane. O.S. sells a Powerboost III Pipe, which is a muffler that fits the O.S. 50SX-H, 55HZ Hyper, and 55HZ-R engines. This muffler is roughly $150, but a set of 6S 5,000 mAh batteries could also cost approximately $150.

Periodically check the area where the black rubber grommet fits into the Kraken fuel tank. If that area is wet, there is a leak and the rubber grommets need to be replaced. Because the fuel tank is pressurized by the muffler or the engine crankcase, any leak would cause the engine to run erratically.

Setting Up the Transmitter

The Kraken 700 hovers nicely from 1,600 to 1,700 rpm. For 3D flying, try 1,850 rpm for Idle-Up 1 and 2,000 to 2,100 rpm for Idle-Up 2. I generally prefer 1,850 to 2,000 rpm for my 700-size helicopters. The Kraken 580 electric model hovered softly while running stock 570mm blades and it sounded fantastic from 1,600 to 1,800 rpm.

With a 6S battery, the Kraken 580 can spin at 2,200 rpm in idle-up without stressing the 6S battery too much. The Kraken 580 is similar to the original Goblin 570 in weight and they both come with the same 570mm blades. With a 6S battery, the model is relaxing and still packs enough punch, but with a 12S battery and 2,350 to 2,500 rpm rotor speed, the Kraken 580 will not bog down, regardless of maneuvers and the amount of collective applied.

A local pilot runs a 12S 3,000 mAh battery pack, spinning at 2,500 rpm, and his Kraken flies like it’s on steroids, but he only gets a 3-minute flight time. Pilots who use 6S batteries with 2,200 rotor rpm can achieve 4 to 5 minutes of 3D flying time and 6 to 7 minutes of gentler flying.

The right rotor speed is whatever makes you feel comfortable and suits your ears and flying style. I usually prefer using the rpm governing feature in my ESC instead of from the FBL gyro because it is a more direct approach and seems to lock in the rotor speed better and the tail wags less.

You can tell how well the governor is holding the rotor speed by listening. If you hear a zinging sound when performing aggressive 3D maneuvers, the rotor speed is probably not steady.

I always take advantage of the dual-rate feature on my transmitter. The high rate is for 3D flying. The low rate is for precision hovering, general circuit flying, and high-speed passes. I set low rate to 90% for ailerons, elevator, and rudder. It is beneficial to use low rate for cyclic to reduce the elevator input sensitivity so that the model does not suddenly balloon upward.

all krakens have a new tail pitch slider and a simplified tail
10. All Krakens have a new tail pitch slider and a simplified tail gearbox design that is lighter and more rigid than the Goblin tail gearbox. The Kraken tail gearbox is narrower and is not interchangeable with older Goblins.

Although there is only 10% difference in total travel, it makes a very noticeable difference in control sensitivity. For both high rates and low rates, I use 40% exponential for elevator and 35% for aileron on most models. I do not use exponential for rudder.

I use a three-position switch for controlling tail-gyro gain sensitivity. For example, with iKON2 and MICROBEAST gyros, I set the gyro zero position for rate mode, position 1 for lower gain heading-lock mode, and position 2 for higher gain heading-lock mode. Most of the time, I fly in position 2.

The only time I fly in position 1 is when doing speed passes at maximum rotor rpm because in high-speed flight in Idle-Up 2, the tail could hunt and flutter wildly if using a high tail-gyro gain setting.

Blade Choice

The stock SAB 690mm carbon-fiber blades included in the Kraken 700 kits are good for all-around flying. They are the same blades that are used in the Goblin 700 and the new RAW. The 570mm blades for the Kraken 580 and Nitro 580 are the same as those that are used for the Goblin 570, and are ideal for 6S batteries.

I do not recommend using 600mm blades if you want more than 2,000 rpm of rotor speed and are running on a 6S battery because the extra disk area will bog down the motor. Beginner and intermediate pilots who want to maximize flight time on a 6S battery should use a 6S battery pack, running at 1,700 to 1,900 rpm.

For 3D flying with a 12S battery on the Kraken 580, the best blade length depends upon the aircraft weight. If heavier batteries are used then 600mm blades will offer a similar disk loading and feel like running a 12S 3,000 mAh battery with 570mm blades. I wish that SAB would introduce a set of 580mm blades with a 2mm wider chord than the existing stock 570mm blades that come with the Kraken 580 kits.

Engines and electric motors have a different torque vs. rpm curve. Electric motors are excellent at providing instantaneous acceleration. The electric Kraken 580 always beats the Nitro Kraken at drag races. With the Nitro version, you have to be more careful with collective management so not to bog down the motor.

Intermediate and beginner pilots who fly the Nitro Kraken 580 can benefit from using 600mm blades because the larger diameter gives more blade inertia, which helps carry the rotor speed through maneuvering transitions. Traditionally, all 50-size helicopters on the market use 600mm blades. Experienced pilots who want a hot-flying Nitro 580 should stay with 570mm or 580mm blades and use a higher rotor speed of 2,100 to 2,200 rpm.

In conclusion, the Krakens are well-designed and tested machines. They represent the pinnacle in RC model helicopter technology.

SOURCES:

Goblin Helicopter

sales@goblin-helicopter.com

www.goblin-helicopter.com

XNOVA Performance Motors

www.xnovamotors.com

AMain Hobbies

(800) 705-2215

www.amainhobbies.com

Novarossi Direct USA

www.novarossidirect.com

Castle Creations

(913) 390-6939

www.castlecreations.com

HOBBYWING North America

www.hobbywingdirect.com

Scorpion Power System Ltd.

support@spihk.com

www.scorpionsystem.com

YGE/Young Generation Electronics

info@yge.de

www.yge.de/en/home-2

Mikado USA

noreply@mikadousa.com

https://shop.mikadousa.com

Kontronik

info@kontronik.com

www.kontronik.com

bavarianDEMON

www.bavariandemon.com/en

Horizon Hobby/O.S. Engines

(800) 338-4639

www.horizonhobby.com/os-engine

Thunder Tiger

service@thundertiger.com

www.thundertiger.com

iKON

(877) 439-4354

www.ikonflybarless.com

BEASTX

info@beastx.com

www.beastx.com

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