On August, 1999, I was present at the World Championship in Poland. I saw Wayne Mann of USA put on a strong contest with his Kalt Omega Zeus, which reminded me I have Kalt Zeus left in the box gathering dust for months! "I am going to fly my Zeus!" I said to myself, and started assembly right after I am back from Poland.
I got my Zeus sometime on the end of 1998. I bought it to complete my collection of the top F3C helicopters made in Japan. My Zeus is the second edition version, which comes with graphite frames, seesaw head (GPZ-II), a new canopy design (dolphin like), and some updates from the first version. With my Zeus, I ordered almost all of the upgrade parts available to the Zeus, which includes the following items:
The first part of the assembly dealt with the upper main frames. According to the instruction I have to construct the upper main frames with the clutch bell assembly and the elevator bell crank. Since I also have the main frame reinforcement brackets I am also putting these onto the upper frames. However, when I put on the metal reinforcement brackets I realized that the screw holes of the bracket doesn't align to the holes on the frames! At first, before blaming Kalt, I test fit the bracket once again to see if I did something wrong, but after some efforts I realized that its Kalt who made the parts wrong, and this frustrate me to the max! In front of me is a helicopter which should be the best money could buy from Kalt, and yet their parts won't fit! I wondered where is their quality control! Later on, I used a jeweler file to adjust the holes on the brackets so that they would fit the frames, but this give me a very bad impression towards this machine! Aside from the brackets, all other things fit. One thing that Kalt had to get praised was that they used high quality Japanese bearings in the Zeus.
After constructing the upper main frames, the assembly of the drive train comes next. The Zeus uses a 12mm hollow aluminum shaft, which is quite hefty. The autorotation assembly of the Zeus is located not inside the main gear but on top of the clutch bell. From fellow pilots who have the Zeus I learn that the stock Zeus autorotation assembly is too weak and they have to change that in about 20 flights or the who assembly would let go. Several pilots here had their Zeus crashed due to problems with the autorotation assembly. Not to take that risk, I used a autorotation assembly from Bell Wood, which is more stronger. The main gear is machined from Delrin, and is secured directly to the main shaft. Pitch change is not through movement up and down of the swashplate, but by a shaft that run inside the hollow main shaft, and link to two metal wires to the mixing base, and the swashplate is not moved during pitch changes. This design gives a larger pitch window than the usual swashplate sliding pitch change mechanism, but makes the pitch change mechanism more complex. The swashplate is a piece of art, where the bull eye with regular swashplate is replaced by several brackets with bearing that makes tilting smooth as silk. After assembling the pitch mechanics, I found that it is not smooth working. Further investigation reveals that the inside of the washout slider that runs up and down the main shaft for pitch change have blur and dents inside the sliding part. As a result, I have to polish the inside of the washout slider using a Dremel. Once the whole upper main frame is constructed I used an angle rule to make sure the frame is straight, and it further took me more efforts to adjust the brackets to do that.
Next up is the assembly of the lower frames and the fuel tank. Once again the optional main frame reinforcement brackets did not align to the holes of the frames. The lower main frame is constructed by sandwiching the two graphite frames with the fuel tank, cross members and brackets in between. This should be a very easy job but due to the problems with the optional brackets it took me great efforts to put together the lower main frame, and I started to get fed up from this... Once the lower main frame is constructed I also checked to see if they are square, then after joining the lower main frame to the upper I have to check once again. Once when everything squared up I loctite all screws to set the whole main frame, and I was exhausted after doing that. After the whole main frame was constructed I was reluctant to continue assembly due to all the hardships.
The main frame and the remains of the Zeus sat inside a box for month, before I had the mood and courage to finish it. Next up is installation of the engine. I used an OS61SX/WC with Hatori 666 muffler. The Zeus' clutch mechanism was one very good design where the fan and clutch were first slotted onto the engine shaft, held in position by the woodruff key, and then the whole assembly was secured by the prop nut. The whole assembly was very clean, and both the clutch and fan were large and strong. The engine is then secured onto the one piece machined engine mount, and then slotted into the main frame with the start shaft. The starting mechanism of the Zeus is from a 6mm shaft that runs from the 7mm hex adapter connecting to the clutch with a dogbane type connector. Then further time was spent to put on the large fan shroud, and since the fitting was quite tight it took me sometime to adjust the shroud to make sure that the fan won't touch it.
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| Assembled upper frame | Note holes not align to bracket |
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| Note blurs inside the washout slider | Bell Wood autorotation assembly |
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| Swashplate | Delrin main gear |
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| Complete upper frame with drive train | Complete main frame |
I chose the GPZ-II seesaw head instead of the usual GPZ-I flapping head that usually comes with the Zeus. The GPZ-II was very light compared to other rotor heads, but I afraid that it might be too weak to take abuse. Before fitting the rotorhead I checked it only to find that a bellcrank that controls the flybar was warped, and I have to get a replacement. Once again I was fed up with this. while waiting for the replacement head I continued to the tail assembly. The tail unit comes fully assembled, with aluminum tail boom, 10mm aluminum tube drive, tail gearbox and tail transmission gearbox put together in one unit. I weighted the whole tail assembly and felt that its a bit heavy. I changed the tail pinion for the option 20 tooth gear that I have, which should speed up the tail rotor for better tail control. The whole tail assembly is secured to the main frame with four "half moon' shaped brackets and four screws. The optional tail mount rudder servo bracket was then secured onto the boom. Then, the tail fins were mounted, and I was unhappy to see that Kalt go cheap with these fins cause they are made of plastic bottle materials, very thick airfoil and looks very ugly and out of place on what should be the top model from one of the major helicopter manufacturer.
After receiving the replacement head, I continue to put on the rotor head and ball links. The rotor head came fully assembled except the flybar, but I reassembled it and changed all the bolts to stainless steel ones along the way while checking it for defective part. The flybar was a 4mm stainless steel rod that goes through the top side of the rotor head, and different from the usual screw pattern as seen in both ends of flybars the Zeus flybar had 5 notches on each end instead. The paddles are to secured to the flybar with a collar that would lock onto the notches. This was a very good design cause it took out some of the guessing and measuring of the distance of paddle on the flybar. After assembly of the flybar, I put the whole rotor head on to a High Point Balancer to make sure the head was balanced. After the head was balanced, it was mounted onto the main mast. Next is the fitting of various pushrods to the mixers and bellcranks. These pushrods were stainless steel 2.3mm type from CMPS. when I reach this point of assembly I have lost all moods looking forward to fly the Zeus after all the hardships.
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| Optional 20 tooth tail pinion | Tail transmission |
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| Tail rotor |
I used JR PCM10X with NES4000 super servos for swashplate controls, DS8201 for throttle, 2700G for tail, and an NES-3000 gyro. Servo installation was much easy compared to the hardships on previous steps.
The landing gear was the plastic and aluminum strut type. It made the helicopter sit high and did not look nice. The canopy looked like the head of a dolphin, which looked nice. However, the decals were very thick and damaged the look of the canopy.
After everything was mounted, I checked the CG of the helicopter, only to find that it was way tail heavy. I then had to place 160 grams of lead inside the canopy to balance the CG.
One day, I brought the Zeus to the field for flight testing. For the first tank I left the engine running idle on the ground to preliminary break in the engine. For the second tank I started the engine and wanted to take the Zeus off, only to find that the tail went out of control like a gyro with reversed direction. I checked and re-check the gyro position, and only to find that the tail rotor rotates clockwise instead of counter clockwise. The reason why the tail rotor rotates counter clockwise in most helicopters was that its the most effective and efficient way. However, with a clockwise rotating tail rotor the tail would be working against the current produced by the main rotor and this de-sensitize the tail rotor. Feeling totally fed up, I took the Zeus home, took out the engine and radio, and sold it at a very bargain price.
Never once before in my helicopter hobby that I hate to finish a helicopter like my experience with the Zeus. Wrong design, unmatched parts and bad quality control just kill what might be one of the best F3C helicopter around. I have had some great times with the Kalt Baron 32 and 46, but the Zeus experience made me think twice about getting another Kalt helicopter in the future.
Kalt was once a giant in the R/C helicopter field, and its history was brilliant. Once Kalt helicopters was used by top pilots like Katsuyuki Sensui, Yukihiro Dobashi, Shigetada Taya, Wayne Mann and Yamaguchi, to name a few. However, recent years Kalt have lost their top pilots to other vendors, and with these pilots absence, lack of new designs, and bad production quality as present in the Zeus I don't think Kalt would survive in the current market. As of writing this web page Kalt was sold by its holding company to HPI. I learned from car guys that HPI products have very high quality, and I hope with HPI's acquisition of Kalt they would improve the quality and design of the old Kalt line of helicopter and turn it around.