T-Rex 450 MFIS tail case
Written by Ashley Davis Friday, 03 June 2005 00:00
Tail CaseThe following is a review of the MFIS Tail Gear Case.
Initially let's take a look at the tail gear case....
The thing that strikes you immediately when looking at the MFIS tail gear case is how small it is in comparison to either stock or other manufacturers tail cases. The second thing that hits you is that iti is a single piece of aluminium and that the CNC quality is outstanding. This is one very compact little unit. The case does not come with any bearings or belt tensioner, so the original bearings and belt tensioner from the T-Rex kit must be fitted. These items can be seen in the bottom right picture in the series above.
MFIS ship a one page set of instructions which guide you through the assembly process. One item that caught my eye was the warning that although the unit is pre-assembled no loctite is used and that loctite must be used on all screws. It's good to see that MFIS have taken a responsible approach in putting this information into their instruction sheet. Assembly is not complex the only difficulty being in finding an allen key small enough to fit the tiny allen bolts that retain the bearings in the tail gear case. I used a 1/20" allen key. The case is machined to a very high quality and the Aluminium is 7075 grade coming in silver or blue anodised. MFIS provide all the bolts necessary for fitting the case as well as some spacers to make sure there is no play in the rear tail rotor pulley once it is in place. The Align bearings I found to be a very tight push fit into the case, requiring quite some pressure to get them into place. This is a good thing as we don't want the bearings moving around in the tail case once mounted. The belt tensioner from the original kit is also re-used and MFIS provide a couple of aluminium spacers to hold the pulley in the center of the case on the center line of the belt.
Installation of bearings, tail rotor shaft and belt tensioner can be seen below :
MFIS don't currently provide a CNC tail pitch slider so I took the liberty of fitting one from another manufacturer. The small arm built into the tail gear case provides a perfect mounting platform for such an item. The case provides a double clamp top and bottom of the boom and once tightened they provide a vice like grip on the tail boom. No worries about the tail case rotating in flight. Using the provided spacers the tail pulley is also sandwiched tightly between the bearings. This is a good thing as the tail pulley should not be allowed to run out of true.
The MFIS tail case is open in design, meaning that maintenance and cleaning is a simple and very quick process with no opportunity for dirt to gather or accumulate. MFIS provide the nice solid platform for mounting a tail pitch bell crank, which is one of the major plus points for this type of upgrade. MFIS have reused the Align bearings and belt tensioner pulley, so there is no improvement in quality or longevity of bearings from implementing this upgrade.
The thinking behind this case is that it allows re-use of bearings that are already available and in possession of the T-Rex owner, plus they are readily available at very cheap prices should they need replacing at any point in the future. This allows for some choices when buying and installing the MFIS case. You can chose to re-use the stock bearings, which will fit perfectly due to the fine machining or alternatively MFIS also do some high quality bearings that can be purchased separately.
The tail case is very light and compact in design and it is certainly not any heavier than the standard plastic case. Below can be seen the final build steps to a completed and functional tail gear case :
Once completed the unit looks very compact on the T-Rex tail boom. Additionally the solid mounting platform for the tail pitch bell crank gives slop free movement on the tail pitch slider. Something that is bound to assist in resolving tail wag issues. The case is similar in width to rival products, MFIS have made the actual CNC case slightly narrower than both stock and rival products but the screw heads on the bearing retaining screws remove that slight width advantage making all the various tail case offerings almost identical in width.
So having completed the build on to flight testing.
After fitting the case I found that the distances for my tail pitch servo had changed, so I had to re-setup my tail servo linkage rod length to get a nice solid heading hold. Having done this the unit performed impeccably with no perceivable flight differences between this tail case and the previous CNC case that I removed in order to fit this one. This is as expected as the tail case doesn't really affect the flight performance as it is just a mounting platform for the components that do affect flight performance.
Positive things about this item are it's compact size, ease of maintenance, good looks and vice like clamping system. Plus it provides that all important solid platform for mounting an upgraded tail pitch bell crank. The unit is CNC machined from a single block of 7075 aluminium and the quality of this machining is outstanding.
With a tail case upgrade I would normally expect to see better bearings as this is really the only performance element to the case but in this example they are not provided and are an optional extra. This really makes it difficult to place this component as a performance upgrade, unless you are also adding an upgraded tail pitch bell crank and taking advantage of the smooth and solid mounting platform that a CNC case provides. What we have here is a solid mounting platform on to which other upgrade components can be built. This is it's main function as well as looking very bling!
Overall I like the MFIS tail case, it's extremely well made, assembles well and functions within it's design specification.It is also a single piece unit rather than two halves, which personally I like as it removes any possibility of the unit as a whole separating (however unlikely that may be with a two piece case). The manufacturing and anodising is also of top quality and I have not seen better. Rival tail cases come with upgraded bearings, this is an option with the MFIS case but the design is based around reuse of existing components and taking advantage of the parts availability of those components. Costs for this unit place it competitively with rivals, although rival units may come with upgrade bearings where as they are an extra with the MFIS tail case. However, the MFIS case is the only one to offer the option of reusing the standard kit bearings or upgrading to higher performance bearings. Which is a nice design point and offers the customer some configuration options as a part of their upgrade.
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