First impressions

Wow!

Does that sum it up? I like this little gem! I almost wish I didn’t have to slow down the assembly of this project by having to document all the typical review items like pictures and text! I wanted to dive right in, put it together, and go flying. I seriously doubted this would take more than an hour to get flying. But this is a review so I need to do it justice despite my selfish intentions of wanting to get in the air as soon as possible!

First, find a large space to lay the box down in, it’s pretty good sized. If you look at the picture you can see a tiny, tiny little motor to the left bottom side. That’s a 400.

Upon opening the box, all parts and accessories were neatly packaged and secured against movement and damage. Nothing will evidence rough handling or sloppy packaging worse than foam, and the foam parts in this kit were flawless. Seriously. I didn’t see a single blemish in any of the foam parts which is a true testament to careful packaging.

In this next picture, let me point out that I cleared away all the cardboard dividers and bubble wrap, and removed all the hardware packages to make for a cleaner picture.

If you didn’t need to glue the vertical fin on permanently, the box would suffice extremely well for a carrying case! The box is this size because the wing and lower fuselage area all one piece of foam. But, the fin needs to be glued in so don’t skip this step. The Pico-Jet doesn’t make much of a footprint anyway; so carrying or storing it is not going to be a problem with or without the box.

The accessories included with the Pico-Jet kit were:

• Permax 400 Motor, pre-wired to run in reverse, with connector
• Push-on 125mm x 110mm white plastic prop (4.9" x 4.3")
• Hardware pack
• Wood parts
• Pushrod cabling
• Elevon strip tape
• Decal sheet

Here’s the rest of the items included in the box:

 

Assembly

I’ve already spent 45 minutes just taking pictures and jotting down notes. I could be in the air flying already! (Okay, enough whining, I’ll stop complaining and get started…)

I want to add one thing to this review, and that will be a running "time total" at each section of assembly. Granted, I’ll be taking more pictures and capturing thoughts in the meantime, but I’m going to track the time spent on each section and provide a running total at the end that reflects only true "assembly time".

Throughout the review I’ll use the same step numbers and descriptions that Multiplex uses in their instructions, so you can follow along if you decided to purchase a Pico-Jet.

One note, though: Multiplex refers to the control surfaces as "ailerons" throughout the instructions. I’ll replace that term with "elevons" in this review since it is more appropriate to their function.

Step 1 – Installing the fuselage lining

In this step:

• trim the black plastic liner
• check for fit
• epoxy in place

There are raised lines provided for you to follow when trimming the part. As you can see from the picture I left the back end of the liner intact, even though the raised line would have you trim it off. There is a recessed ledge in the fuselage foam that allows the black liner outer lip to fit flush once installed. It’s this level of attention to detail that continues to impress me with this kit, especially for a foam plane. I checked for proper fit, then epoxied the liner in place once satisfied.

Time Spent: 3 minutes

  

Step 2 – Freeing the elevons, fitting the horns

In this step:

• cut the elevons free
• tape the hinge line
• assemble the elevon actuators

I used a fresh #11 hobby blade to make this step easy, but made such clean cuts to free the elevon ends that I had to go back and sand a little clearance. Just insert a small piece of sandpaper between the elevon and the wing, and lightly sand some clearance between the moving and non-moving parts. DON’T CUT THE HINGE LINE! Matter of fact, don’t do anything until you put the elevon tape on the top surface of the wing as the instructions specify. You could score the top surface hinge line like they recommend, but I opted to tape it and then work the elevon free. It leaves a blemish-free hinge line this way.

   

The elevon actuator is assembled from a servo arm, a piece of wood square stock, and a screw. The wood is pressed into the splined side of the servo arm, then fastened with a screw. Make sure that your wood is "square" to the arm of the control horn when you insert it. If it’s off by a bit, the wood has already formed a spline of it’s own, so it can be rotated and re-inserted until everything is square. Make sure both actuators are assembled this way, and are identical. I found that the wood square stock was longer than the relief provided in the elevon where it mounts, so either extend the relief in the elevon or trim back the square stock to the proper length. One item not covered in the instructions, but noted in an addendum is this: the servo arm has a long and short side. The addendum asks you to trim off the shorter of the two arms. I had already performed this step on my own before I noticed the addendum sheet. Luckily there’s only one item in the addendum! I checked for clearance and epoxied the actuators into place on the elevons.

Time Spent: 12 minutes

 

Step 3 – Installing the receiving system components and pushrods

In this step:

• route cables
• mount servos
• make final connections

I spent more time on this step than what was necessary, but I wanted to make sure the routing was done precisely per the instructions. Especially since this was a product review! I spent some time fiddling with the pushrods and servo placement to make sure I could clear everything. Once satisfied with the routing, I epoxied the servo mounting rails to the plastic fuselage liner. I then installed two CB688 Critter Bits mini servos to the rails and selected an appropriately sized servo output arm to attach to the servo.

I cut the cabling and sheath of the pushrods to the length specified, then trial-fitted them in the troughs provided. This made for a straight shot from servo to control horn, which is the way to go.

I bent the control horn end of the wire as specified, put it into the control horn, then CA’d the black collared spacer into place. This makes for a convenient, low-profile installation. I chose the hole furthest out, as I intended to do the same at the servo end.

Time Spent: 34 minutes

Step 4 – The power system

I pulled the propeller off of the black friction hub and re-assembled it reversed for a pusher configuration.

Time Spent: 10 seconds!

Step 5 – Suppressing the motor

Suppression is not needed, it’s already internal to the motor as noted in the instructions. They caution you to check for interference, and they provide a fix if that happens.

Step 6 – Mounting the motor in the model

The instructions call for using 5 minute epoxy to glue the motor in, but I’ve had wonderful success on my Twinstar (also by Multiplex) by mounting the motors with some very aggressive double-sided tape I have. This worked fine on the Pico-Jet as well, plus would allow for some different motor options later on in this plane’s life. If in doubt, though, always use what the manufacturer recommends.

Time Spent: 1 minute

Step 7 – Gluing the fin to the fuselage

I epoxied the fin to the fuselage after checking for proper fit.

Time Spent: 1 minute

These steps are starting to go faster now!

Step 8 - Attaching the canopy

I glued the rear canopy tongue on, which slides underneath the tail piece to secure the aft end of the canopy. I then did some equipment placement checks to see where I could best affix the rubber band hold-down blocks that retain the front end of the canopy.

I finalized placement, and glued the blocks in place and attached the rubber bands.

Time Spent: 11 minutes

Step 9 – Final Assembly

Final assembly was mostly completed in the previous step! Once the receiver, speed control and battery placement are identified, it’s a simple step to peel off a few pieces of the "hook-and-loop" fastening tape (have to call it that since Velcro is a trade name!) and secure the items in their proper place.

Time Spent: 2 minutes

Step 10 – Control surface travels

I had installed the pushrod in the outermost hole of the elevon control horn, and was planning on allowing the placement of the push-rod connectors at the servo output arm to determine the amount of throw. (You always want to strive towards using the outermost hole on control horns and servo arms when installing pushrods to minimize slop. You can achieve the same control throws by using the inner holes on both control and servo arm, but any slop will be greatly exaggerated. This is good practice no matter what the airplane).

Since I was already at the outer hole position on both horn and servo arm, I measured elevon deflection "as is". I measured 10 mm for elevator input and 10 mm for aileron input, and the instructions called for 15 mm each way. I thought 10 mm (3/8") was PLENTY of deflection, so I chose to test-fly it this way. My sole reason for doing this requires a little explanation:

The servo arm that you trim and attach to the elevon actuator rod (square bass wood) seems plenty long. But if you look at how much arm length is below the hinge line you’ll see that the amount of horn length available ABOVE the hinge line isn’t that much. I’d pretty much say it’s a necessity that you use the outermost hole on the elevon control horns. Do a trial fit and installation of this and I think you’ll see what I mean.

Time Spent: 1 minute

(I only had to verify the throw in my configuration, so your time on this step will likely vary depending on how much monkey-ing around you have to do to on it)

Step 11 – Balancing

Again, most of the time spent on this step was already performed in Step 8. There isn’t a lot of experimentation required here, as the battery needs to be close to the servos for proper balance. There are a variety of placements you could engineer, but I’m not wild about putting receivers and speed controllers in FRONT of batteries! So I left the battery in the forward location.

Balance is checked by placing your fingers on two raised bumps on the bottom of the wing placed at the recommended CG location. Great idea! Especially on flying wings where the true balance point required can be difficult to determine. To get to this balance point I ended up double-decking the receiver and speed controller right in front of the servos, and placing the battery right in front of this stack.

Balance was now fine, so on to the next step.

Time Spent: 2 minutes

   

Step 12 – Gilding the lily – applying a little decoration

Yes, that’s the text directly from the instructions! I believe the age-old expression implies there’s no sense spending time making a flower as pretty as a lily any prettier…

Granted, the Pico-Jet is rather good looking in the raw, but it’s far from "lily white". The gray foam could stand to have a little contrast to it for orientation in flight. I fly all winter long, so a gray airplane against a gray sky needs a bit of color. I pulled the decal sheet out and made a few choices as to which ones I would use. After a little cutting, trial fitting, and then final placement I ended up with this:

   

Also, I noticed on the tail that the foam injection port left a sizable depression in the foam. A well placed sticker takes care of this!

   

Time Spent: 6 minutes

Step 13 – Preparing for first flight

At this point, I stopped the clock on tallying the assembly time. The standard recommendations made in Step 13 are pretty much items you should perform on any new airplane, any new radio installation, and certainly should be done at least every 10-20 flights on an old airplane! So I won’t charge the time spent on this step and remaining steps against the total assembly time.

This step is one of the longest text items in the instructions, and contains many of the standard "cautionary" items experienced fliers typically follow. Don’t gloss over it just because you think you know it all. There’s good information contained there. And I was glad I normally follow this regiment, as you’ll soon see.

I did a final tightness check on all pushrod connections, made sure the servo leads were fully in the receiver sockets, and double-checked the instruction steps to make sure I didn’t leave anything out. I charged up the battery, and took everything outside for a test flight. There was a lot of snow on the ground, which I like having for test flights! A little bit of "cushion" if needed…. However, I’m no electronics expert but leaving the receiver antenna touching the snow seemed to be as bad as laying it in water, so when I performed my range check I placed the Pico-Jet on the picnic table. My choice of radio system used was the Hitec Focus III radio system, since I only needed 3 channel operation and the Focus III had elevon mixing at your disposal with just a flip of a switch. The receiver is compact, and was a perfect fit. Also, the speed control used was provided along with the Pico-Jet review items and was a Multiplex PICO control 400 20/12 BEC.

When I performed the range check, it was obvious these two items did not like each other AT ALL! This is not a criticism of either the Hitec system or the Multiplex speed control. This sometimes happens, which is a good reason to follow the pre-flight procedure. I did rule out motor noise as a cause through a little testing. The Hitec radio system is compatible with my Jeti, NewCreations, and Castle Creations speed controls. The Multiplex speed control is compatible with my other Futaba AM radio systems and FM systems. So it was just a bizarre case of incompatibility. I had to retreat back to my workshop and replace the Hitec system with my Futaba FM computer radio with mixing. Range checks were performed once again and everything was smooth and precise. I was now on to the test flight.

Flight Testing

The instructions caution you against performing an un-powered test glide. This statement was in there for a reason obviously, so I heeded it. I was a little nervous about hand-launching a pusher model, as anyone should be. My other pusher flying wings I launch with no power, then power up when my hand is clear. The beauty of the Pico-Jet is that even though it is a low-profile pusher configuration, the bottom keel is set up such that the prop is protected from the ground.

It would follow that your hand is protected somewhat as well, but there is still sufficient prop arc on the sides to contend with so be careful. I set the throttle to half, and gave it a heave. Launched straight forward from shoulder height, the Pico-Jet lost a foot or two of altitude before I got my hand to the controls, but it wasn’t enough to alarm me. I hit full throttle and she was off and climbing!

What amazed me was that neither elevator nor aileron trim was required in the test flight or any subsequent flights. I had paid careful attention to aligning the elevons to their original positions (as molded, before cutting out), and with the balance point specified in the instructions, it was flying by itself. That alone impressed me. But I wasn’t content to leave it in free-flight mode for long, so I had my go at yanking the sticks around. I performed some basic pitch and roll maneuvers to determine control sensitivity. Pitch was surprisingly authoritative, which isn’t always the case with flying wing designs. Roll rate was also very comfortable. Recall that I had chosen to go with 10 mm rather than the recommended 15 mm travel for elevator and aileron inputs (measured separately, not as a total). Total travel is greater when combined in elevon mode. This 10 mm value was more than sufficient to fly the Pico-Jet rather acrobatically, so I’m not certain the 15 mm throws in the instructions would be necessary. As a demonstration of this, later on in the flight I did a full rolling straight-line flight without losing altitude. If you can accomplish that, why go with greater throws? However, the flexibility is certainly there for you to set the Pico-Jet up to whatever your desired response.

Still within the first battery flight, I performed loops from level flight, and continuous rolls. Flight speed is certainly comfortable, but you won’t win pylon races with it. I found the speed to be just right for a fun-filled, stress-free flight. I set up for landing as soon as I heard the first hints of motor speed decay, as it was still the first flight and I wasn’t sure of how well it would glide. The landing was smooth as silk, and just like landing any other well-mannered plane.

With a fresh battery I launched it for the second flight, and applied a little more power than before. There’s no reason to go full throttle on launch, as I found that somewhere between ½ and ¾ throttle is fine. After gaining altitude, I put it through its paces a little further. First off, I wanted to see how slow I could get it to go. I shut the motor off, and kept easing back on the elevator. No hint of a stall, so I kept pulling further and further back. I bottomed the stick out against the gimbal limits, and still no stall. The plane would stray left or right a bit during this maneuver, but that was it. I added full up trim and tried to stall it again, but it wasn’t going to happen. This is with motor OFF, though, so don’t take my demonstration wrong. With full power and pulling full elevator stick, you have a hard time getting it to do a "true" stall but you can get the nose straight up in the air if you take a running start at it. If you do this at too low an altitude you could be doing a bit of repair. But a true stall? No, it’s hard to accomplish. When I pulled up into a vertical climb, it would go for a while but as soon as airspeed dropped it would just "blip" forward and start flying again.

I continued flight with a few mock landing approaches and was getting really comfortable with the Pico-Jet. Truly a docile bird. It will get going pretty fast especially on a downhill run, but also will slow down quite well. On the OPPOSITE side of docility though, I attempted a full rolling circle. Well, not quite. Full rolling straight-line flight can be performed without losing altitude, but I’ll have to "work up" to the rolling circle with this bird for now.

Indoor Pico-Jet!

You can’t tell from the text, but it’s about two weeks later now. I had a head start on this review, then I relaxed and fell behind! However, the good news is that I got a chance to take the Pico-Jet indoors. After our Freeze Fly here in Fort Wayne on February 19th, I went up to the Oakland Yard Athletics dome in Waterford, Michigan. It’s not anywhere near football stadium sized, but it’s good enough to fly in. Zagi’s were the most popular bird there, and had dedicated time zones in which to fly. The other time zones were reserved for other slow fliers, like the true indoor models. I easily flew my Ferias in there, as well as my e-converted Lanier U-2 foamie. But a testament to the Pico-Jet is that I flew it indoors as well. I could easily do figure-8’s, and very tight circles. I didn’t quite have enough room "in the straightaway" to do a full roll, but I was awfully tempted. Flying in still air is simply incredible, and it allowed me to do some really neat things with the Pico-Jet that night. When the battery started getting low, I would just bring the Pico-Jet down to about a foot off the ground and make it’s way from the far end of the dome straight towards me. As it got closer, I started pulling back on the elevator stick and increased throttle a bit. The nose rose, it slowed down nicely, and right by my feet I gave it the last bit of elevator input and it came to a gentle rest. A nice handling little airplane!

Noted exceptions:

The only discrepancy I noted between the instructions and the kit contents was that the instructions call for a balsa elevon actuator, but the kit provided hardwood. Good choice!

Neat items –

• What I originally thought were extra servo arms in the hardware pack are actually pushed and secured onto the elevon actuator for use as control horns, which I thought was a novel idea. Plus, the wood chosen was dimensionally correct for a tight, secure joint. This type of actuator allows the force of inputs to be spread out across the foam elevon.
• Air inlets are provided into the battery bay, as well as inlets at the motor area.
• Molded in slot for routing the antenna wire out the right wing panel (bottom side of wing)
• Molded plastic tray for radio/battery compartment to save the foam from gouging as well as additional structural strength.

Things I’d change –

Although I like the concept of the actuator rod and the use of a servo arm as a control horn on the elevons, there was one thing I’d consider changing or asking Multiplex to look into regarding the control inputs. If you move the elevons by hand, you get some "play" in them without moving the servo or pushrod ends. If you look at it, this is caused by having the pushrod connection point above the hinge line, the point of torque input to the actuator rod below the hinge line, and the "pivot point" of the elevon control horn slightly rear of the hinge line.

I experienced NO problems with this in flight, and control was not at all affected by this design. However, as most electric modelers are prone to do, I can see someone wanting to put a higher powered motor on the Pico-Jet. I’m sure it won’t be long before someone puts a ducted fan or brushless motor on it. (I did think about it for a little bit!) At higher speeds and consequently higher aerodynamic loads, this could cause some problems. If you fly it stock, or even go up to 8 cells, I wouldn’t bother changing this. It flies fun as is. But if you start bumping up the input power, this is one area you might consider checking into. Just a cautionary note for those who never think 100 watts is enough!

Second item is the control rod attachment at the elevon horn. I’m not sure how much I trust the little black spacer and a drop of epoxy. It wouldn’t hurt to use a Z-bend here or a more standard connector. I’m currently flying it this way, but I may change it in the future.

Due to using the Multiplex style battery connections on the Pico-Jet and the fact all of my other Speed 400 equipment is on APP connectors, I wasn’t able to measure amperage and power directly. Therefore, the Power and Power Loading figures are estimated. MotoCalc provided the estimates used above based on motor, battery, and prop inputs.

The instructions state the flying weight of the Pico-Jet should be 530 grams, which comes out to 18.7 ounces. As you can see from the figures, mine came out a little heavier but not by much. At a wing loading of only 9.5 oz/sq.ft, it’s already so light you wouldn’t notice the 1.3 ounce difference.

Final thoughts

If you’ve kept track of my "time spent" you’ll see that it took 67 minutes to put together and 6 minutes to decorate. I didn’t include pre-flight checks and flight testing in this count, because you need to do that for any airplane anyway, and it shouldn’t count against assembly time.

But don’t rush it. Take your time and do it just like the instructions tell you. Even doing this, the Pico-Jet is at most a one-night assembly (and that’s even after you’ve fed the kids, watered the dog, washed the car, read the paper, and kissed your wife goodnight!)

It’s a quick build, and flies great. The Pico-Jet is a winner in my book, an A-plus airplane!

E-mail Contact

Patrick J Mattes <pat-ingrid-mattes(at)juno.com>