Greg Covey

Hi,

I am reviewing the [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVEP7&P=7]Multiplex Mentor[/link]. The Mentor is a replacement for the Magister and is a robust trainer and tug (tow plane) made of ELAPOR (pronounced el-a-pore) foam. Medium CA glue used with an activator (or kicker) as the only method of gluing recommended by the manufacturer. This radio controlled model is electric powered and Almost-Ready-to-Fly (ARF). It is meant for beginners to intermediate fliers.

Trainers have been around since the very beginning of model flying. The so-called .40-size trainer was offered in a multitude of variations all over the world. The beginner is expected to cope from the outset with an easily damaged all-wood model and a motor which is not properly set up or even broken in. It was no surprise that this type of "first model" was often the modeler's last.

The Multiplex Mentor was designed with the beginner in mind. The ELAPOR foam provides a robust, high-strength structure that is easily and quickly assembled using CA glue. The aircraft's flying characteristics are simply outstanding! When using the mating Multiplex Brushless Motor Power Pack ([link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVEP8&P=V]M993228[/link]), which contains a motor, ESC, Prop, and hardware, the trainer provides reliable, maintenance-free power flight after flight.

Features:[ul][*] Wings are removable for easy transport[*] Radio Compartment: Accessible under wing[*] Landing Gear: Pre-bent aluminum 0.098" (2.5mm) thick[*] Steerable 1" (26mm) tailwheel[*] Two foam 2-3/4" (70mm) Wheels included[*] Landing Gear: Pre-bent aluminum 0.098" (2.5mm) thick[*] Aileron Control: Dual servo[*] Elapor foam, 2.5" (63mm) spinner[*] Peel and stick decals[*] Building Time: Ready to fly in several hours
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Specifications:[ul][*] Wingspan: 64.2" (1630mm)[*] Length: 46.1" (1170mm)[*] Wing Loading: 14.58 oz/sq ft (44.5g/sq dm)[*] Flying Weight with 3 LiPo Cells: 4.3lbs (1950g)[*] Airfoil: Flat bottom high-wing placement[*] Center of Gravity: 3.3" (85mm) Back from the wing's leading edge at the fuselage[*] Elevator Throw: Up 0.59" (15mm), Down 0.47" (12mm)[*] Rudder Throw: Right to Left 0.59" (15mm)[*] Aileron Throw: Up 0.59" (15mm), Down 0.27" (7mm)
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Greg Covey

The Mentor parts fit into a custom foam base that protects them during shipment. The kit includes a large decal sheet, manual, and all the hardware needed for completion.

The mating Multiplex Brushless Motor Power Pack ([link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVEP8&P=V]M993228[/link]), contains a Himax HC3528-1000 motor, Castle Creations Phoenix 45-amp ESC, APC 11x5.5 e-prop, adapter, and mounting hardware sets.

rjmanzuk

Subscribing. Employing different power system in mine ...

Torque 2814/605 brushless outrunner
APC 14X7E prop
AirBoss 45A Elite brushless ESC
4s 4450 mAH TP High Pro LiPo

Looking forward to sharing tips as we progress. Mine's still in the box, awaiting a few accessories.

Greg Covey

Your setup should work just fine. You may have limited tug power but may not even be planning to tow other planes.

The assembly begins by gluing in the motor mount pieces. I was impressed at how the plastic pieces fit perfectly into the foam mold fuselage halves. A little medium CA on the fuselage inside and spray kicker on the plastic pieces was all that I needed for a quick strong bond.

Xpress

It's a multiplex plane. How could you have doubts?

The Mentor is a very aerobatic plane on high rates. It will do flat spins, blenders, inverted, knife edge, and any other aerobatic maneuver in the book. I think you will love flying it.

Greg Covey

I'm still waiting on my Hitec servos to arrive so there will some delay before I get back to building the Mentor. Most of the initial steps in assembly require the servos to be mounted before the two fuselage halves get glued together.

dawnron1

Hi Greg,

I'm looking forward to the rest of your review, this looks to be another winner from Multiplex!

Ronnie

Greg Covey

Hi Ron,

Welcome aboard and feel free to chime in anytime. My Hitec servos arrived so I can resume the Mentor building.

For the elevator and rudder, I'm using Hitec HS-475HB servos. These are standard size servos with ball bearings and Karbonite gears. Each servo weighs 1.41oz and has 61oz/in torque on a 4.8v supply. They press into place on the fuselage and are held by a few drops of glue. I cut away the outer holes in the servo arm so it would fit in the servo compartment of the fuselage.

The ailerons will use smaller Hitec HS-85BB "Mighty Micro" servos. The servos weigh only 0.67oz each and deliver 42oz/in torque on a 4.8v supply. The HS-85BB servo is meant to fit in the smaller aileron compartments in the wing.

Greg Covey

The elevator and rudder control snakes are made from a thin metal rod and an inner and outer set of tubes. The Z-bend of the rod connects to the servo arm and the outer tubes press into the fuselage after lining the channel with medium CA. I used Pacer Zap CA+ (PT-02) and Zip Kicker spray accelerator.

Note that the thicker control rod for the steerable tailwheel (which does not use an inner tube) is crossed over the rudder control rod at the servo arm.

Greg Covey

The wing screw supports snap together and then get CA'ed into the fuselage.

rjmanzuk

Why the cross-over? Wouldn't that increase the probability of binding? Is it to get the tiny bit of extra moment arm to the tail-wheel rather than the rudder?

Greg Covey

The cross-over is just another example of the elegant German engineering that went into the Mentor. It is simple and requires no fancy linkage hardware. There is no binding because the Z-bends are a different size so the tailwheel control rod rides over the other one.

I decided to install the aero-tow mechanism because it was well designed and easy to install. I used an old Expert SL300 Micro BB servo I had on hand. Just about any micro-sized servo will work for this feature. I'll cut the control rod later when I active my receiver. Perhaps I'll tow the Cularis for a test.

Greg Covey

The next step is to join the fuselage halves. I have found from assembling previous Multiplex Elapor models that using medium CA and a spray accelerator like the Pacer (PT-15) Zip Kicker makes this assembly procedure quite easy. After first test fitting the two halves, I applied CA to one side and sprayed kicker onto the other side. You can then press the two halves together being careful not to warp the fuselage tail in the process. It is helpful to do this on the floor with towels under the fuselage so it can be compressed with multiple hands. I finish this procedure by checking all the seams and re-applying CA where needed.

Greg Covey

The tailwheel unit and main undercarriage are installed next. I assembled them from the matching diagrams in the manual without issue. A 1.5mm hex wrench is needed to tighten the wheel collars. Be sure that all wheels spin properly when finished and use Locktite on all the nuts and hex head "grub" screws.

Greg Covey

The main undercarriage is installed with four M4x68mm flat head screws into three of the thick plastic plates. The plates sandwich the fuselage and provide a solid foundation for the gear mains. Everything fit well and Locktite was applied to the four nuts that sit inside the fuselage.

Greg Covey

My Mentor [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVEP9&P=7]Servo Pack[/link] finally arrived. It looks like Tower Hobbies will have them in stock soon. The pack consists of two HS-322HD servos (for elevator and rudder) and two HS-81 servos for the ailerons. It also contains the two 6" and two 12" servo extensions needed to complete the Mentor.

When I return from my trip to the Adirondacks, I plan to finish up the Mentor and give it some test flights.

Greg Covey

After first cutting the control surfaces free, the swivel pushrod connectors are mounted to the control horns. The elevator and rudder connectors use the outermost hole in the horn and the aileron connectors use the second hole from the outside of the horn. As with everything else on this model, the pushrod connectors fit perfectly onto the control horns and the control horns fit perfectly into their custom slots of the control surfaces. I used a small dab of Zap Z-42 thread locker on the nuts of the pushrod connectors to keep them in place.

The stabilizers glued easily in place onto the fuselage. After first testing the fit, I spread medium CA onto the fuselage area and sprayed the stabilizer area with PT-15 Zip Kicker accelerator. This made for a quick assembly as the stabilizers are easy to center in position. The same technique was used to mount the tailwheel assembly.

All the pushrods were inserted into the swivel connectors and lightly tightened for now. When the receiver is made active, I will center the servos, adjust the pushrods, and tighten the grub screws with a dab of Locktite.

Greg Covey

The aileron servo openings in the wing are perfectly designed for Tiny S, HS-85, or HS-81 servos. They snugly press into place with a small amount of CA to hold them. Since the servo arm was not easy to unscrew after mounting the servo, I decided to first center them with my live receiver and Rx. battery pack.

I used Hitec (57345S) 12" Aileron Extensions to route the servo wire to the center of each wing half. A small piece of foam was cut in the wire channel to accept the joining cable connectors. I used a small amount of CA to hold it in place and then clear cellophane tape along the entire channel.

The spar covers were installed with my usual CA and spray kicker technique. The key here is not to get any CA inside the channel where the carbon tube must slide.

Greg Covey

The motor assembly begins by soldering the connectors on both ends of the Castle Creations Phoenix 45 ESC. I did not find any shrink tubing for the ESC motor wires so I used my own. My battery connector preference is Dean's Ultra connectors. The Himax HC3528-1000 motor came with the connectors already on the wires.

The Mentor motor bulkhead has an innovative adjustment for thrust angle. I used the recommended starting points for right and down thrust.

Greg Covey

My Mentor Power Set came with many parts that are not needed. I wasn't sure if I had received a prototype kit or if the Power Set was meant for multiple models.

A complete bulkhead motor mount kit was included but not needed. I only used the 4 motor mount screws in the X-mount kit. The APC 11x5.5 prop, Multiplex prop adapter, and spinner adapter are all used.

Greg Covey

After mounting the motor with the 4 screws from the X-mount kit, the whole assembly is screwed into place from the front of the fuselage nose. Note how easy it is to change the thrust angle by adjusting the screws.

Greg Covey

I placed my Hitec Electron 6 receiver and Multiplex ESC (CC Phoenix 45) in the recommended locations. When the battery is in the back of the fuselage chamber (as suggested) the plane balances perfectly! Note the gap in the fuselage at the center of the wing leading edge. This is where the aileron control wires are routed from the wing to the inside of the fuselage.

The 72MHz antenna wire is routed along the bottom of the fuse toward the tail. I used clear cellophane tape to hold it in place.

Greg Covey

The Mentor was designed with exceptional air flow through the inside of the fuselage to cool the motor, ESC, and battery pack.

Greg Covey

My Multiplex Mentor was Ready-To-Fly at 63oz (3.9lbs) including the 10-oz flight battery pack and extra tow servo. I measured the following static power setups. You can see that for a little more money, you get 10% more power from the 30C FlightPower pack.[ul][*] 315w, 30amps, 81w/lb w/[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMDN5&P=ML]ElectriFly[/link] 20C 3s 3200mAh pack[*] 350w, 34amps, 90w/lb w/[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRWB5&P=7]FlightPower[/link] 30C 3s 3200mAh pack
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[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&P=8&I=LXSGC7]Multiplex[/link] also has their own cost-effective 20C 3s 3200mAh pack.

Greg Covey

I tested the Mentor at a local schoolyard just down the street. As expected, it flew very predictable and offered no surprises. Take-offs required some rudder correction in the cross breeze but it had plenty of power for basic aerobatics and could slow down to a docile crawl around the field. I needed only a few clicks of elevator and aileron trim to keep it flying straight. Landings were as simple as turning off power to the motor and gently flaring the elevator as you watch it glide onto the grass. My flights lasted for at least 10 minutes while performing aerobatics. Using the 30C Flightpower 3s 3200mAh pack provided a noticeable increase in power.

Video coming soon...