Monday, August 1, 2011

Build a Hobby Zone Super Cub From Parts

Hobby Zone's Super Cub LP is a great trainer and many a RC pilot has cut his teeth on this plane. Not only is it a stable slow flyer, but it is quite robust and easily fixed if damaged. The only problem I've found with the RTF kit is that it comes with a 72MHz FM radio system that some might consider obsolete since the new 2.4 GHz system has been introduced by Spectrum. If you plan on flying at the local soccer field where their could be others on a FM system, they could turn on there transmitter, be on the same frequency as you and wham, your model is reduced to a pile of Styrofoam. One way to circumvent this problem is to build your Super Cub from parts. This not only gives you components that can be used in another model as your skills progress, but it's also cheaper if you already have a 2.4GHz transmitter. Building it from parts and using 2.4GHz technology also gives you the ability to easily make upgrades such as adding ailerons, adding a more powerful motor or even navigational lights. All of which would require that you replace the original FM radio gear if you bought the RTF version. You might as well make the leap now and build from parts so that you have the radio system that you will ultimately want to have anyway.

If you decide on the parts build route, here is what you will need:

Part# HBZ7185 Fuselage. $18.99. This item includes the firewall, both control rods, battery box and door and the wing posts.

Part #HBZ7120 Wing. $19.99 Includes struts.

Part# HBZ7125 Tail Assembly $11.99. Includes Stab, Fin, Rudder, elevator, tail wheel and control horns.

Part# HBZ7126 Cowl. $2.99. Includes mounting screws.

Part# HBZ7106 Landing Gear. $5.99. Landing Gear. Includes tires, skirts and hardware.

Part# HBZ7134 Motor. $10.99 Includes Pinion

Part# HBZ7129 Gearbox Assembly. $8.99. Includes prop shaft and hardware.

Part# HBZ7310 Decal Sheet (Blue Scheme) or HBZ7110 (Red Scheme)$3.99

Part# HBZ7101 Spinner $.99

Part# HBZ1002 Prop 9x6 $3.49

You will also need a 20amp electronic speed control with a BEC (battery elimination circuit) Be sure you get a "Brushed" speed control and not a "Brushless" as the stock motor has brushes.

A five or more channel Spektrum 2.4 GHz receiver. I used a Orange 6 channel receiver from Hobby King.

(2) Ultra Micro Servos. I used Hitec HS-55's

The first thing I did while building mine was to make a couple of modifications to strengthen the SC, that being Reinforcing the wing saddle and battery box. The videos below by NeCubFlyer do a very good job of describing these mods. If you want to add ailerons or cover your model in econokote, check out his youtube channel for more great videos on the subject.

Assembly of the parts is pretty straight forward. A link to the instruction manual is below. Super Cub LP instruction manual.

Here is a video from georgesjunglerc that shows the basic Super Cub assembly:

One thing not covered in the manual is installing the servos as they come pre-installed with the kit version. The fuselage has cut outs in the foam where the servos set. You can install them as the factory does by setting them into a bed of white adhesive caulk, or you can attach them to a set of wooden rails secured to the foam with epoxy like I do. With the servos screwed down to the rails they are very secure and easily removed if a repair becomes necessary.

First thing I did was to bind the receiver to my transmitter and set the servo arms so that they were 90 degrees to the servo case. This gives me equal servo throws in each direction. Then I cut a couple of pieces of 1/2"x1/8" bass wood the width of the inside fuselage. The servos were then centered on the rails and lined up so that they were side by side by side and butted up to each other. I marked the hole locations on the rails leaving a small gap between the rail and servo case so that when the servos are screwed down, they are not binding between the rails.

Once I had the servos attached to the rails, I mixed up some 5 minute epoxy and apply it to the underside of the rails. Then I set the whole assembly in place, holding it until the glue had set. To attach the control rods, I removeed the control arms from the servos, ran the Z bend of the rod through the desired hole on the arm and then attach the arm to the top servo gear securing it with the screw.

Finished Radio Installation
Finally, you will want to align your wing and make a couple of registration marks with a Sharpie. Start by measuring the distance from each wing tip to the side of the fuselage, Measurement "A" in the below diagram. Adjust the wing side to side until both "A" measurements are equal. Then measure from the button on the top of the wing to the middle of the intersection of the vertical fin and rudder. Measurement "B" on the diagram below. This makes sure your wing is not skewed. Once both "B" measurements are the same you can take your sharpie and make a dot on the leading edge of the wing and a corresponding dot on the fuselage. Do the same for the trailing edge and fuselage and you have a quick reference point for aligning the wing anytime it is installed.
Wing Alignment Measurements
One last mod I did to my Super Cub was adding a length of clear packaging tape to the leading edge and wing tips to protect them from dings. I also added two strips of 3M extreme strapping tape at the center of the wing where the rubber bands land to reinforce this area.
Finished Super Cub with Red Decal Scheme

Cool Super Cub RC T-Shirt

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