Below are a few thoughts on the short kit available through the Flying Models plan service. This document is not intended as a full construction manual. It is simply a collection of informative notes and musings, based on building and flying my model, as well as the Kitten that Carl Hampton brought to the 2018 NEAT Fair.

Flying Carl's model pushed the plans onto my building board, and I hope these notes will offer value for your build, so you can fly your Electric Kitten sooner.

Note that the smaller images below can be enlarged by clicking. They will open in a new tab, preserving this window.

Update, September 2, 2019: I've just added a Materials and Supplies List page, to show what else you will need to complete your Electric Kitten.

ASSORTED BUILDING NOTES

This airframe builds quite quickly. The simple wing has only a few parts, and can be completed in an evening or two. The fuselage is traditional stick and stringer construction to keep the weight down, and takes just a little longer. The bare airframe of my Electric Kitten weighed just 7 ounces with the floats, and the covering, motor and radio gear didn't quite double that number, ensuring a very low wing loading.

The laser cut wood parts are all labeled and should be pretty self explanatory, but please don't hesitate to reach out if you have any questions.

One detail worth mentioning is that the ribs, wing tip plates, and fuselage gussets are mirrored. With a little care you can have the part markings facing in the same direction. I oriented the gussets and tip plates with the markings inward, so they would not show through the covering.

Building the wing is straight forward, though do notice that the W1 center section ribs end in a point, and so are only supported by the center section sheeting where they meet the trailing edge.

I've received some emails wondering whether the wing spars shown on the plans are strong enough. I firmly believe they are. This is a lightly loaded, slow flyer type model, which does not benefit from excessive power or weight. As long as you build and power it as designed, and pay attention when picking your spar stock, it should be fine. Both my model and Carl's have been looped and rolled repeatedly without wing failure.

I cut my spars from a single 3x36 inch sheet of firm 1/8-in balsa. I was careful to choose a sheet with straight grain and 10-12 pound density. This care gave me spars without internal stresses, that stayed straight once cut. You may want to cut your spars slightly oversize, leaving room to fine tune them once any internal stresses reveal themselves. A good straight edge and new X-Acto, or single edge razor blade, are more than enough for the job, though take light passes to avoid having the grain pull the blade off line.

Another option is to use a table saw. I use and highly recommend the bench-top Byrnes Model Machines table saw for much of my model work, but a full size table saw can work fine with a high tooth count, narrow kerf blade and a zero clearance insert. Naturally, I must admonish you to use all due caution with any power tools.

I have also included a mat board template of the original firewall as drawn on the plan. This gives the location of the original beam cutouts for the S400 motor and gearbox, which may be helpful for some, as well as a small hole to indicate the thrust line. The larger hole serves for cooling airflow and ESC access. You will need to get a little creative for your setup, or opt for the optional laser cut motor mount, discussed below.

The two long pieces of mat board in your kit make up the float side template. These fit together with fingers as shown, and can be glued with Elmer's or Titebond. There are also two small rectangles, cut from the float side pieces, that are roughly the size of large postage stamps. They are intended to be glued over the template finger area, with one shorter to accommodate the reduced height of the float side behind the step.

The line etched across the fingers should remain visible. This denotes the location of F4. The other former locations are also indicated.

The black pen markings shown here were handmarked for reference in these images. The kit templates are marked only with the F4 indicator across the fingers.

FLOATS

The plan and article do not indicate a preferred grain direction for the float bulkheads. I opted for horizontal to help tie the float sides together. Vertical grain would resist compressive loads more effectively, but the Kitten is light and slow, and it isn't hard to land gently. I try to pick a firmer piece of wood for cutting the bulkheads and cowl cheeks. If the grain direction still makes you nervous, glue a piece of 1/8 sq or 1/16 x 1/4 vertically along the sides of F3 and F4 before assembling the float. I don't think F5 or 6 will need any help, and you shouldn't be touching down as far forward as F2! The bulkheads are etched with a short centerline indicator to help align them to the upper deck.

In addition to the laser cut bulkheads, the floats will require at least four more sheets measuring 1/16 x 3 x 36. You can cut both sides for a single float from one sheet, so two of those sheets will go to the float sides. Both upper sheeting pieces can be cut from two feet of a third sheet, while its remainder and a fourth sheet should be enough for the lower sheeting. I choose some 6-7 pound wood for my floats, to help keep the weight down.

The actual float side shape is shown on the plans, and it fit my assembly quite accurately. I assembled my floats upside down, using magnets and weights to hold the deck flat against my building board as I added the bulkheads and sides. You will obviously want to remove these before installing the bottom sheeting.

I worked forward and aft from the step when sheeting my floats. Doing so saves the trouble of any critical fitting. Just keep adding pieces of stock until you run off the ends. I rough cut oversize pieces for the lower sheeting using a pair of scissors, and did the final shaping with a sanding block after everything was glued up. Take care to keep the lower chines sharp when sanding your floats, to help your Kitten lift off more easily.

For those wondering why the kit includes templates for the float sides and not wood parts, the answer is simple economics. Not everyone has ready access to a water flying site, and so it doesn't make sense to increase the price of each kit with more wood that a good percentage of people will not use. The floats require 4 sheets of balsa, so the savings are significant.

The template also allows you to hand pick the wood if you do build floats. Just place the template on a sheet of 1/16 balsa and trace around it with your favorite hobby knife. This template is exclusive to the short kit at this time, and is not included when purchasing a plan and template set. The plans do show the float side pattern.

Sorry there aren't any photos of building the floats. They are little more than basic balsa boxes, and I knocked them out late one night without a camera handy. I cut the float spines and spreader bars from clear pine with my Byrnes table saw.

FINISHING

The lightweight airframe is more than strong enough for flight, and we should strive to avoid adding weight unnecessarily with careless equipment and finishing choices.

Full strength plastic films are not recommended. They will add significant weight, and could potentially distort the airframe when shrinking. Fred Reese's prototype was covered with LiteSpan, which I believe is also on Carl's model. The unfortunate Solarfilm situation has made LiteSpan/SoLite/Litefilm tougher to find these days, and with limited color options as remaining stock runs out, but it is still available from some vendors.

Do use the lightest covering you can source. LighTex from AirBorne Models is a great choice with 14 opaque options, and 6 transparent. UltraKote ParkLite is about the same weight, with 16 opaque colors, but none transparent.

I covered my entire model with Micafilm, secured with SIG Stix-It. I had some remaining Micafilm, it is pretty light, and I like its look. Yes, Micafilm is also a discontinued Solarfilm product.

For reference, my bare airframe weighed just shy of 7 ounces before covering, with the floats installed. The covering, servos, pushrods, receiver, motor, and ESC added another 6 1/2 ounces. It now weighs 17.4 ounces flight-ready, when carrying a 2S 2000mAh battery. After a few flights I realized I don't need that large a battery, and now use packs from 700 - 1000 mAh. That has reduced my flying weight to just under a pound, and still gives me over 20 minutes of duration.

There is one important trick to remember. Normally we cover the bottom of a boxy structure first to hide the final seams underneath, but that is not best when covering floats. Whenever a float is moving through the water, there is some lateral water flow trying to escape past the float sides. Covering the float sides after the undersurface will leave an edge to catch the water, much like shingles installed upside down on a roof.

POWER & GUIDANCE
There is no reason to put more than 100 watts into the power system, or load the Kitten down with a large battery. Fred Reese powered his original with just a geared Speed 400 motor and a 7-cell 600-1200mAh nicad pack. This combination would have provided something around 50 watts of power and flew the Kitten well.

I found an unused AXI 2208/34 in my collection, and when paired with an APC 9x6 Slow Fly prop and a 2S 2000mAh lipo battery it gives about the same power as Carl's setup. I initially flew this setup with 3S packs. The Kitten was excessively over-powered, and the motor was over its design limits. Watch the short take off demo in the maiden flight video if you don't believe me.

Another suitable power system I can recommend is the Cobra 2208/34, with the same prop and 2S batteries I am using with the AXI. These two motors are effectively identical, even down to their mounting geometry.

I am now using 2S batteries in the 700 - 1000mAh range, as my typical current draw is averaging below 19 watts. If you believe that too much power is almost enough, the Kitten might not be your best match. Save the weight, and relish its slow flight capabilities.

The radio requirements for the Electric Kitten are modest, and a pair of Hitec HS-55 servos and a light receiver are ideal.

My control throws are currently set as noted on this chart. For what it is worth, my transmitter is usually set to high rate rudder and low rate elevator. I do switch both controls to high rates to toss it around a bit, and to low when handing the transmitter off to a new pilot.

I've had a couple emails about the elevator pushrod. I read the plans as showing it exiting between the fuselage sides, and minimized the gap with a scrap of balsa.
Note the "reversed" elevator horn.

You can also see my sewn thread hinges in this view.
I think they lend an appropriate "old school" touch.

MODIFICATIONS

As with any build, there is room to accommodate personal preferences, and equipment and materials on hand. I made a couple of changes during my build, ever mindful of adding unnecessary weight or complication.

A single 4-40 socket head cap screw just under the center bend pins the wire in place, and clamps the box a bit when tightened. The original gear lacing holes provided registration guidance for the gear box assembly. A disk on the forward box face captures the T-nut so it doesn't push out, and the cap screw can be accessed through the main cabin.

My cross bracing is .020 wire, with 3/16-inch wide strips of .006 brass shim stock wrapped around the landing gear wire and soldered for the anchor points. The bracing wires are not soldered. Simple U-bends at each end hold them in place, and let me take it all apart if needed.

The tape is much faster, lighter and easier to use. Having now been through installing the magnets, I would likely just tack the cowl in place with medium CA.

IN THE AIR

Most of my flying with the Kitten has been a series of circuits around the pattern, searching for that perfect "pitter-patter" return to the water. Such flying averages just over 2 amps, and I typically change the packs somewhere between 30 and 45 minutes, just to ensure I don't get stranded off shore. Given those numbers, I plan to try out some much lighter batteries as well, and should be able to take another two ounces off the flying weight.