Written by Jeff Quayle Thursday, 20 April 2006 00:00
The following is a review of the MicroHeli Precision Tail Set Pro
I would like to thank MicroHeli for providing TrexTuning with this unit for review and Ashley for allowing me to review this for the site.
The ProTail V3 is a complete tail replacement unlike several of their previous offerings which provided an upgrade to specific parts of the tail. A lot of the components from this tail have either been previously offered separately or are largely based on previous components. The tail pitch slider however is a big step forward in terms of precision and smoothness. It appears MicroHeli's goal was to produce the highest quality tail available for the trex. (no matter how many microscopic parts they had to use!)
Let's take a look at what you get...
Like most MicroHeli parts, the product is well packaged. Everything is safely tucked in a plastic case with foam padding. The tail comes in two pieces and there is a loose screw and washer in the case that you need to locate. My washer got lost in the foam and I had to go back and search for it during installation. Also included is a sheet with diagrams of how all the little parts have been assembled as well as a list of the 46 parts including the 10 bearings take make up this little beast. There are also 2 allen wrenches included that fit all but the smallest of the screws.
As always, it is recommended that you go over any part with metal to metal connections and ensure that loctite has been applied. Most but not all of the bolts on the tail already had loctite, but it only takes one bolt falling out mid-flight to cause a catastrophic tail failure. It is also recommended that you apply a small amount of lubricant to the tail shaft.
The tail comes almost fully assembled. There is a single screw and brass washer that attaches the tail pitch slider that need to be installed. The washer needs to go between the slider and tail case. If you install it incorrectly the slider arm will bind against the tail case. Be sure to apply loctite when installing this, however it's difficult to insert the screw thru the pitch slider and then apply loctite at the two parts need to be pressed right against each other before you can screw them together. I found using a small tool and applying loctite from the opposite end to be a good solution. Make sure you get it down in the threads. The screw will push excess loctite back out. Just wipe it away after it's installed. It's important that the screw be snug but not tight. Too much pressure and you will compress the bearings.
Here are some pictures of the tail fully assembled
The next step is installing the tail on the boom and getting the tail belt on. This is almost identical to installing any other cnc tail case, especially the align cnc tail.
First there is a single screw on the right side of the tail case that clamps the tail case on the boom. Remove that screw and twist the tail case onto the boom. Make sure that the boom is inserted all the way into the case and bottoms out against the back. After you are sure that it is all the way on and aligned correctly use a bit of loctite and secure the tail to the boom with that screw on the right side. Next we have to take off the left side of the tail case so we can run the belt around the tail pulley. Remove the 4 screws from the left side of the case shown in the picture below. Notice that the side of the case has 5 holes, but the second hole back on the bottom is not used. Pull the belt out loop it around the tail shaft pulley. Replace the side case and bolt it back on, again using a small amount of loctite. There are 2 large aluminium washers that go on either side of the tail fins when you install them in the grips. Adjust the tension on the blade grips so that they are even and fairly snug. Bold on the vertical stabilizer and you are done.
The arms that attach to the blade grips were secured using a press fit pin. This had the potential of coming loose under the vibration and extreme revolutions tail pieces are subjected to. These pins have since been replaced and are now secured with a brass pin and E clip. Here is a picture of the V1 tail on the left and V3 on the right.
As you can also see in the above pictures the first version of this tail had the blade grips on the trailing edge instead of the more traditional leading edge used by Align. Although I did not any issue with tail performance with the V1 tail, it did require changing your servo direction on the rudder as well as on the gyro. I'm not aware of other issues with running the tail in this configuration, but MicroHeli may have switched to leading edge grips just to avoid confusion in setting up the tail.
This tail was installed on my main heli made up of a heliup frame, Medusa 28-40-3400 and TP2100 4S lipos. It was also paired with the incredible duo of a Futaba GY401 gyro and Futaba S9560 Servo. These two together will make almost any tail look like a superstar and the ProTail was no exception. The tail performed beautifully and never gave the slightest hint of trouble. The tail was very well balanced and showed no signs of vibration. It's very difficult to credit the tail itself for the level of control and response when the gyro and tail servo are also playing a major role in the tail system. What I can say is that that everything moves effortlessly and there is no binding at any point of the pitch slider range. Slop is also nonexistent and these factors can only help the rest of the tail system work better and with less effort.
I wanted to consider what people are hoping for when they lay down their visa for that new cnc tail. There are a few common reasons people upgrade to a cnc tail.
1. Stronger parts that should break less often
2. Less slop / smoother movement (which should also give better control)
3. Insane head speeds that require cnc blade grips
4. The ever popular 'Bling Factor'.
The ProTail has the last 3 down cold. Response was crisp and very precise. My head speed was just over 3k in idle up and running without the Align reduction gear at the time. I had the misfortune of testing the crash durability of the Protail with my V1 tail. I was never able to determine the cause of the crash but there was some type of tail failure and the heli started to piro out of control. It was able to come down under throttle hold, but the tail was first part to touch. Below is what's left of the tail.
Going from left to right: You can see that both sides of the tail case bent like putty. The main body of the tail case was ok. There is a nice twist in the arm that attaches to the tail slider. The smaller arms on the tail slider are also bent. The blade grip look ok, but the bearings are shot one side. The two black bits are what's left of the fins. Misc screws (most of them bent slightly) and finally the tail shaft - sheared in two.
In conclusion, I think this is a very well designed, excellent performing tail. However because of it's poor crash durability and inability to purchase several of the parts individually I think it's best suited to the more experienced flyer that rarely crashes.
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