Moore
Senior Heliman
Location: California 93094-0940
| Article and photos by Joe Howard at East Coast Scale HelicoptersThis article and photos are a few years old. I am fortunate enough to have it reside on my website. It is just one of many outstanding write ups that Joe has contributed to the helicopter modeling community. Keep up the good work Joe, and thanks for sharing your expertise.
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Well, its close to IRCHA again, and Vario has released another variant of the NOTAR Helicopter. This time it is the MD 900 Explorer. When I heard a couple of years ago about the NOTAR, I though it might be this one, but the 520N came first. I was very excited to hear that they had made this model. Germany sent me the first prototype to test and get my opinion on the kit. When I received the kit, and opened the box, I could not believe how large this helicopter was. I saw what the recomended build weight of the heli was, and could not believe that a heli this size could only weigh this much. It is a full 1600mm long. It is so big, that people have commented on how small the blades look on the heli, then realize that the blades are actually 725mm long. They then realize how big this fuse really is. After the usual prep of the fuselage, I started construction. There is virtually no wood in this kit at all. Vario has redesigned the bottom fiberglass pan so that the mechanics are now enclosed in it, and then the pan is mounted to the fuse. There is a 7" diameter fiberglass tube which goes under the pan to the floor which not only helps to support the mechanics, but with the required holes drilled into the duct, allow air from the fuse into the fan unit. There is also carbon tube struts which help to support this pan. The rear air duct off the mechanics has changed in as much as it is a straight shot for the air to go down the tail boom, unlike the 520N, where there is a large curve in the duct to the tail. The tail rotor servo is also now mounted on the top of this duct eliminating the need to dissconnet the cables every time you want to take the mechanics out of the fuse. I modified the door cable setup to the tail rotor servo by putting an additional servo arm in front of the tail servo and making it a pull pull setup, eliminating the strain on the tail rotor servo. This allows you to tighten the cables to the intermediate servo arm so that there is no slack to the door. I made up 2.5 mm pushrods from the tail rotor servo to this intermediate arm, and it works flawlessly. The back air duct is constructed the same as the 520N, with the exception that I varied the size of the vanes on the left side of the tail. I started with a 35mm vane, then the next was 40mm, and the last at the back of the boom was 45mm. With each vane slightly larger than the preceding one, each one is in the air flow coming down the boom. The tail has more than enough power for quick tail turns, and there is no delay in the reaction of the tail at all when you move the stick. Vario recomments the Webra 70 engine with this kit. I tried this engine and several others with limited success. I finally settled on the Webra 75 using 30% nitro and the supplied exhaust from the 70. This combination has proved to be very good, and this heli now flys better than the lighter 520N. My all up weight with blades before the paint job was 14lbs 9oz. After my paint job, the weight was 14lbs 15oz. The additional 6 oz did not hurt the performance of the heli at all. I would not suggest going over this weight. This was measured with blades, without fuel. The heli is a stunning flyer. It is very impressive in the air.
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Well, I am not that happy, I sure will miss her... Anyway, I wanted to get some input on some of the radio equipment required for Vario's MD900 kit.
