Greg Covey

The new Clipped Wing Cub 48 from [link=http://thewingsmaker.com/index.php]The Wings Maker[/link] is available in two color schemes. It is made from top quality balsa and plywood construction and comes with all hardware and accessories. The built-up rib wing and tail section comes with all the control surfaces pre-installed.

I'll be converting this model to clean and quiet electric power. It is essentially half the size of my World Models 1/3 Scale [link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=952]Clipped Wing Cub[/link].

Specifications:[ul][*] Wing Span : 63 in / 1600 mm[*] Wing Area : 620 sq in / 40 sq dm[*] Flying Weight : 5.5 lbs / 2500 g[*] Fuselage Length : 47 in / 1200 mm[*] Engine Required : 2-stroke 0.40 - 0.46 or 4-stroke 0.52 - 0.56[*] Radio Required : 4-channel radio w/ 5 standard servos
[/ul]

Greg Covey

The Cub came solidly packed in the box. Each piece was sealed in plastic and the fuselage was held secure by custom cardboard. An 11-page manual with detailed drawings and a decal sheet are also included.

Greg Covey

A closer look at the fuselage revealed that the pre-painted fiberglass cowl and pre-cut window plastics were safely stored inside. A transparent dummy cowl is included to help design your original cuts on before transferring them to the painted fiberglass cowl.

The fuselage was built solid yet light and the covering looked top-notch!

Greg Covey

Converting the Cub to electric power is easy. Simply multiply the desired watts per pound performance level times the flying weight to get the motor power class. Since the Cub has clipped wings, I'll want enough power to do some aerobatics so I simply multiply 100w/lb times the 5.5lb flying weight to get my motor class of 550w.

On motor choice that fits this class is the AXI 4120/14 motor using a 4-cell LiPo pack and a 13" to 14" prop. Assume a loaded LiPo voltage of 3.6v per cell or 14.4v for the 4s pack. Divide your desired 550w by 14.4v and you get a reasonable 38.2 amps maximum current draw.

Greg Covey

After opening the large bag of parts, it was nice to see the smaller bags with numbers on them that matched the instruction steps in the manual. This makes it easy to find the right set of parts for each step.

Greg Covey

Since the ailerons are already pre-installed, the first step of the assembly is to mount the servo and linkage in each wing half. I use a JR Sport MN48 Mini servo which provides 48oz/in torque. I also used a JR (JRPA098) 12" HD servo extension. Note that the Cub has a pre-placed string to help run the servo extension to the bottom side hole near the chord. This will drop into the fuselage when the wing is attached.

All the linkage hardware and keepers are included and the aileron has pre-placed pin holes to drill slightly larger for the control horn screws. The recommended aileron swing is +- 10mm from center.

Greg Covey

The wing halves are jointed together by two aluminum tubes. The smaller one is pre-mounted in one side and the larger one slides into pre-made channels. A finished plywood stiffener is used on the top side to strengthen the trailing edge hold-down area when screwed into the fuselage. Two pre-installed wooden dowels line up the wing with the fuselage and keep it from lifting.

The instructions call for gluing to two wing halves together including the aluminum tubes but I am not convinced this is necessary so I plan to keep them removable for now.

Greg Covey

The power system components are a pre-enjoyed AXI 4120-14 motor and a new E-flite 60-Amp Pro Brushless ESC. I re-located the stock glow engine mount holes 1/4" toward the center and used #8-32 hardware with 1" spacers. An additional larger hole was drilled for the motor/ESC wires to feed into the fuselage.

The mount was simple and solid.

Greg Covey

The fiberglass cowl installed easily using the supplied screws and rubber hole protectors. I opened the front hole in the cowl using a Dremel tool to allow the base of the motor adapter to protrude without rubbing.

Greg Covey

The stabilizers mounted easy using 5-minute epoxy. Both pieces had the covering pre-trimmed and only the horizontal stab needed to be aligned properly. The vertical stab fit in place like a puzzle piece and I found no alignment issues.

The steerable tailwheel assembly was mounted to the fuselage bottom with two screws. The arm was secured to the rudder using the supplied bracket.

Greg Covey

The main gear assembly is installed into channels along the fuselage bottom. You simply need to cut away the covering to expose the channels. Four straps are screwed in place to secure the gear assembly. I discovered that the strut braces could be secured using the same hole as one meant for the strap if you slightly angle the brace. The location for the brace did not match the manual assembly diagram so I could not find it initially. A rubber grommet provides bounce absorption for the main gear assembly when landing.

The wheels are secured with a collar on each side and the other one is hidden by the screw-on hub. The pant is secured by three brass braces, screws, washers, and nuts on each side. I used thread locker on the collar grub screws and pant screws.

The overall look of the landing gear was very clean and scale.

Greg Covey

The side windows were glued in place using Beacon (or Bond) 527 because it dries fast, flexible, and clear. I used the supplied screws and rubber eyelets to attach the windshield.

Greg Covey

I installed the elevator and rudder linkages using the supplied parts and threaded rods. Rubber keepers were also supplied to secure the clevis. The servo tray is pre-assembled so you only need to glue it in place with epoxy. I used JR DS-821 Digital Sport Servos for both control surfaces. Note the empty spot where the throttle servo would normal go on the glow-powered setup.

gosch

I did escentually did the same swap except I used an E-fite 46 on mine. I found where the winshield screws were interfeared with the wing installation so I moved them down a little more. I kept my wings as a 2 piece rather then 1 wing. As long as the struts are used there is enough structure there to be solid. I used a different tail wheel assembeley so I didn't put a load on the rudder. I test flew it 2 monthes ago and it was great. The draw back is I didn't cut an opening fow battery install so I must remove the wing for this. You will be happy with the setup like that.

Greg Covey

Thanks for the information.

On electric conversions of scale models, it is often difficult to access the battery. Sometimes you can make a hatch to access the battery, other times it is just not feasible. I often choose to keep the scale look intact and recharge my battery inside the plane. This can be done safely when using a quality balancing charger like the FMA [link=http://www.fmadirect.com/category.htm?id=4]Cellpro[/link] series. I install the pack before putting on the wing and fly all day or weekend without disassembling the wing between flights.

What makes this in-plane charging work is by first disconnecting the battery connection to the ESC with an arming device like the MPI ([link=http://www.maxxprod.com/mpi/mpi-21.html]6790[/link]) High current Arming Switch. Once the battery has been disconnected from the ESC, you can safely charge/balance the LiPo pack by having access to the small node connector. The MPI switch makes it easy to keep your plane safely disarmed in the pits when not in use. The On/Off switch on the ESC is always left on and you simply pull out the double Sermos plug.

I'm using a 4-cell FlightPower [link=http://www3.towerhobbies.com/cgi-bin/WTI0096p?&N=N&C=&P=7&S=0000000&F=LXWNU7&L=FPWP0318&S1=FLIGHTPOWER&S2=&S3=&S4=]EVO25[/link] 3700mAh pack that weighs 13oz. This is positioned up front just behind the firewall and held in place using Industrial Strength Velcro. The inside formers were cut to allow the pack to sit flat against the fuselage bottom. The ESC is then mounted to the side wall using Velcro. Both components are in the air flow system shown next.

Greg Covey

The motor can be easily cooled by air flow if you first widen the opening in the cowl and then create an exit path underneath by cutting a vent. If you drill some holes in the bottom half of the firewall the air can enter the fuselage to cool the ESC and battery pack as well as enhance the flow past the motor.

An easy way for the air to exit the fuselage is to remove the covering around the last section near the tail. A little red paint on the bare balsa helps to hide the opening.

Greg Covey

Instead of screwing the pilot mount in place, I held it with Velcro so it can easily be removed when taking the battery out. The painted pilot and mounting platform pieces are all included.

Greg Covey

My 1/6th scale clipped-wing Cub was ready to fly at 76oz without battery. I still needed to paint the mock manifolds before gluing them onto the cowl and add some of the supplied decals. The APC 14x7 e-prop was a good fit for ground clearance and the Higley ([link=http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=spn108&search=Go]SPN108[/link]) 8mm x 1.0mm Safety Spinner Hub added a nice scale touch.

The Cub was Ready-To-Fly (RTF) at 89oz (5.5lbs) using the 13oz FlightPower 4s 3700mAh pack. I measured 470 watts at 37amps using full throttle. This provides a performance level of 85w/lb which should be plenty for scale aerobatics.

Greg Covey

As I wait for better weather to test fly the Cub, I spray painted the mock exhaust pipes and valve covers. The plastic pieces fit well against the cowl and I used Pacer Plasti-Zap to secure them quickly. This is a special CA formula for plastic kits and works well here simply by pressing the pieces against the cowl for 10 seconds.

Greg Covey

I had an opportunity to test fly the Cub off pavement and it performed very well. It has off the ground in about 15 feet of runway using only half throttle. The CG seemed perfect so we trimmed it out and had some fun.

Although I did not get any video on this initial testing, we did take some photos. I am anxious to fly it again off grass and get some video.

flying photos by "Papa Jeff" Ring

Greg Covey

flying photos by "Papa Jeff" Ring

Greg Covey

flying photos by "Papa Jeff" Ring

Greg Covey

We flew the Cub 48 on a nice sunny day in early May. The winds were 10-15mph and about 45 degrees off the runway line. The Cub had plenty of power, and, as expected, performed very well. We flew for about 10 minutes with plenty of aerobatics and had 4 take-offs and landings on the same pack charge.

Take-offs used about half throttle and we had no problems performing giant loops, hammer heads, and inverted flight. We saw no issue with the wing that I left unglued so it can easily be broken down into two halves. The Cub 48 is well designed, has excellent performance, and looks great in the air!

[link=http://www.gregcovey.com/reviews/Cub48.wmv]The Wings Maker Cub 48 Test Flight Video[/link] (16.5meg)

Greg Covey

One modification I usually do on wings struts after the initial test flying is to replace the stock screw and nut with a hitch pin clip. The clip allows for easier assembly and breakdown in the field without tools. I drilled a tiny hole in a 5/32 diameter rivet for the hitch pin clip to slide through. The slack from the top of the rivet to the hole was taken up by a washer or two. You can also drill the hole closer to the strut to eliminate the need for washers.

texasclouds

Now that you've flown it a while, would you have set it any different? I'm interested in doing the same to this cub.