Fury Extreme/OS91SX-H

The picture to the right shows the CNC machined metal cooling fan. Very high quality! This is a collet type fan which allows very accurate alignment upon assembly.

The grooves on top of the fan are for two rubber dampners that the clutch uni-ball assembly is driven by. The fan is mounted with the brass collets and spacers in place on the bare crankshaft of the 91.

The fan blades are slightly curved and have a taper airfoil to help move more air across the head. I'm sure it is going to balance well and run true with little or no fuss.

This fan will set you back about $55.00 if you upgrade to it from a regular Fury. The Fury Extreme comes with it standard.

The photo's below show the cooling fan painted bottom and the collet assembly in the photo to the right. The fan was painted flat black on the bottom except for the 3/8" strip which is bare metal. This will be my reflector for the optical sensor I made for the GV-1 governor. The sensor includes an emitter and receiver that will see the beam bounced back from the shiny area and give a pulse to the governor. I have ran this system before in a Raptor and it performed quite well. The photo on the right shows the collet set. It contains shims, two brass collets, two dampners and two hardened metal cap screws.

The photo above show the fan tool. I really thought this was a cool thing for MA to include with the kit. This nifty tool allows you to hold the fan and tighten the engine shaft nut while holding the fan in place. You can really crank it down and this tool is really helpful during assembly. It isn't required but MA did the right thing and included it.

The photo shows where I took my runout measurements on the cooling fan with my dial indicator. To my pleasant surprise the total runout was 0.0015", you gotta love that! The photo above doesn't show the exact setup when I measured the runout. The engine was squarley mounted on a wood table and slowly spun around. I trust my measurements were accurate. You can see the rubber dampners installed into the fan. They are supposed to flush with the top of the fan or no more than .25mm higher. They are tight and difficult to install, take your time and don't damage them.

Here's a side view of the OS-91 with the metal fan installed. It's ready to drop in the heli.

Here we go. The engine is mounted tightly to the motor mounts. The mounts remain loose enough to move the engine around to get the correct alignment. Notice the thim metal shims between the motor and the motor mount. These are specifically for the OS-91. The YS-80 has a different shim set.

Here's a side view of the mounted engine. You can see the two bolts on the right are in a slot on the engine mount. This allows you to raise or lower the motor to get the proper clearance for the clutch. MA provides a tool that you install betwen the clutch and the engine to assure proper clearance. You simply place the alignment tool between the clutch and motor and push the motor assembly up until the shim is snug. While holding tension on the motor, gently snug the engine bolts. Later you can back them out one at a time and locktite them properly.

Here is a picture of the switch mount. Notice the carbon stand off rods which also secures the front left shoud arm in place. I opted to use the high current power switch as I will use digital servos on this heli and want to be able safely fast charge the 2700 mah battery I plan on using in this ship.

Here is a shot of the rear shroud mounting arms installed into the frame. Notice the plastic shims inside the arms.

Here's the cooling fan shroud. It comes in two pieces, a left and a right hald. It seems quite strong and is very light. I ended up modifying it further than the text below shows. See 7-28 build.

You don't assemble it before you install it in the heli. You actually install one side and loosely mount it then install the other half of the shroud and mount it to the support arms then screw the halves together with the provided hardware.

Using the OS-91, you need to cut out a hole in the fan on the inner side so the carb can breathe. I did this in 5 minutes with a dremel. I had to mount one side of the shroud in place and see where the carb was and made a mark with a Sharpie where I need to cut. While I was at it, I cleaned up all the flashing on the edges of the shroud.

There was alot of flashing from the mold, it would be wise to remove it all so it doesn't wind up in your engine later!

Here's a shot of the left half of the shroud installed in the heli to check for clearance around the carb. There isn't any. o I needed to cut out a hole so the carb can breathe. It is on the inside of the shroud right in the curved area. I opened up the hole large equal to the O.D. of the carb and ran it downward toward the cylinder head to facilitate easy removal of the engine. The photo above shows a molded scew hole between the cylinder and the carb body. All of this material was removed from the shroud so the engine can drop straight down without hitting the shroud under the carb area. The photo below shows how the opening was cut out. I sanded the endges and made sure all flashings were removed from the molded plastic.

Here's the assembly bag for the tail rotor case. I really like the way MA packaged the parts. Every bag has a printed label with a number on it which the manual refers to during assembly. This really helps you build in stages and not have too much going on at one time. Concentrate on what you're building when you're building it and only open the bag you need to complete that particular assembly.

The photo above shows the tail input shaft assembled and ready to drop in the tail. I have to tell you, this was a difficult assembly for me. I wasn't used to this type of design at all. After tinkering with it for a while it all made sense and I proceeded. The bearings and spacer slide up against the white delrin coupler. You then install the gear and locktite the bearings to the shaft and the set screws in the gear. You don't want this stuff coming loose.

The new pitch slider assembly for the Fury Extreme. Be careful tapping on the spoked clip. It is easy to over snug it causing the bearings to be notchy, back off by tapping the other way with a wood block and lightly tap it until the pitch fork can spin without any drag. Don't make this any looser than it needs to be, just loose enough for the assembly to spin on bearings.

Miniature Aircraft's

FURY EXTREME

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