Apogee Gyro Chaser

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TheAviator

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As promised, a little look at the Apogee Gyro Chaser. I accidentally had the kits sent to my parents house, so it took til now to get to it.

As is standard from Apogee, the quality of the kit is good. I hesitate to say very good, for a few reasons I will note later. Balsa is middling weight, but helicopter blades usually cannot cope with being made from contest balsa, so this isn't a bad thing. The laser cutting is spot on; Tim really did his homework with this one. Everything fits very nicely, and anything that needs sanded is slightly too tight to ensuring that a good fit can be obtained. (Wood thickness tolerances are rather loose at this scale, so too tight is pretty standard.)

The vacuum formed nose cone is of okay quality. It is made from good plastic and rather light, but the cuts made to free it from the sheet are a little ragged. Dimensionally, it is a little small, but not so bad to be of much concern.

The body tube is a slight downfall of this design. It's heavy, and there is no way around it, at least for a kitted design. I haven't assembled the booster airframe yet, as I am considering my options for making it lighter. I think I'm going to go the Ryan Coleman route and peel a layer or two from the inside of the tube. I may make up a fiberglass tube for my second attempt. The centering rings for the motor mount are also the thick paper type. 1/16" ply or fiber would probably be more appropriate.

The only other minor complaint that I have is that two blades are cut from one piece of stock, and the third is cut from a different piece of stock. This almost ensures that the third blade is going to be out of balance with the other two.

Now, the best part of the kit: the hub. It is extremely simple, combining the hinge, blade stop, and band hook all into one simple plywood piece. These pieces are hinged via a small aluminum tube to a plywood hub. The slot in the hub is deliberately too small for the aluminum tube to pass through, ensuring perfect alignment every time. Ultimately, the hub is made from only 8 pieces, of which only one is not self aligning. The hub alone, IMO, is worth the ~$17 price of the kit.

I made two very minor tweaks to the kit. First, I airfoiled the blades, tapering the trailing edge and rounding the leading edge. This was done on the dowel I formed the blades on to preserve the shape. On that note, as in the instructions, the blades are wetted with glass cleaner and formed around a 3/4" dowel. I didn't have a 3/4" dowel, so I wrapped plastic wrap around a BT-20 and formed the blades on that. Rather than using a strip of cloth, I used an ACE bandage to wrap the blades. The bandage is nice because the stretchiness allows for easy control of the tension.

Secondly, I shortened the main shaft to just allow the length of the blades to fit above the piston. This was just to save weight, and I'll probably shorten the airframe to match.

All in all, good kit from Tim and Apogee. A for design, B+ for execution. I will be definitely flying them this contest season.

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Thanks Brian for the review. I have to wonder if altering this to mimick a S9 bird would be an improvement to decrease weight and increase altitude. Can the hub be mounted to any nose ? Did you weigh the blades to see if they were close ? Let us know how it flys !
 
I was going to weigh the blades, but I got impatient and couldn't find my gram scale. I bought two kits and I'll make sure to weigh the next set.

The hub can be mounted to any nose; it is a plywood plate mounted to a 1/16" ID aluminum tube. The tube then slips over a 0.060" carbon shaft that composes spine of the model and gives a free-spinning hub. The nose acts as the upper stop to keep the hub from coming off the end of the shaft. I would increase the size of the hub plate so that the blades can be spaced farther apart and take full advantage of a 40mm body. I have some ply sitting around, I'll give it a try next week some time and let you know how it goes.
 
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