Intro: Simple RC Stick Plane Build(CAD Model Included)
This is a simple RC plane designed around a 1/2''x1/2'' dowel for the fuselage. The advantage to such a design is the ease of modification -the electronics and any desired sensors can be placed almost anywhere along the fuselage. The plane is propelled via a brushless motor spinning a 10'' propeller. All electronics are powered by a 3 cell LiPo battery.
CAD model (f3d format) is attached.
- 1/2''x1/2'' wooden dowel (poplar/pine)
- 2 Sheets white 20''x30'' Addams (Dollar Tree) foam board for wing&stabilizers
- Piano or other stiff wire (<1/16'' diameter) for control rods
- Wooden block 1/2''x3''x1'' (I cut mine from a pine board)
- 1/8''x1/2'' aluminum stock for landing gear
- Wheels appropriate for environment (I used 2.5'' diameter foam wheels)
- 2 1'' 1/4x20 bolts and nuts for mounting landing gear
- Mounting hardware for brushless motor (X or block type mount screws)
- Propeller collet
- Hot glue
- Control horns/ linkage stoppers (See step 4 for a DIY alternative, built from a popsicle stick)
- Any brushless motor 370 and 480 size motor around 800-1400 kv will fly this plane with the appropriate prop
- 10x7'' prop
- 30A ESC
- Spektrum 6ch parkfly receiver
- 3s 1000-2200mah LiPO battery (BE CAREFUL)
- 2x 9g Servos
Step 1: Drilling Fuselage Holes and Mounting Motor
As per the CAD model, .2'' holes must be drilled 3'' and 11' from the front of the poplar dowel to mount the landing gear. If you plan to belly- land the plane over grass, this is unnecessary.
The 1/2''x3''x1'' wooden block is added next to mount the motor. I recessed mine back about 1'' back over the fuselage to protect the motor in the event of a crash. Obviously, the propeller/shaft still sticks out in front, but at small angles to the ground the motor is completely protected by the fuselage. Screws can be used for a stronger mechanical bond, but I just epoxied the block to the fuselage. IMO this is strong enough, as the motor doesn't have enough power to break this bond.
Next, simply bolt together motor/motor mount and bolt this to the wooden block. In the interest of safety, I left the propeller off at this point ( I had to connect electronics later to center servos).
If you wish to attach the wing with brackets rather than making a permanent joint, the above image should help. Refer to step 3 for more details.
Step 2: Building/ Mounting Wing and Stabilizers
The wing is a 36'' "Armin" wing, built with a 7'' chord in two 18'' halves as per Experimental Airlines's technique. For a complete video tutorial series on how this is done, search "Armin Wing" on YouTube- the wing on this plane is built almost exactly as per his instructions (though there are no ailerons), so there's no point in re-inventing the wheel. Or wing, for that matter.
The horizontal and vertical stabilizers, on the other hand, were carefully sized for performance. Their shape is not very important, as this plane has enough drag to make the sweep on the horizontal and vertical stabilizers aerodynamically irrelevant. Feel free to make them rectangles.
In the interest of aesthetics, I swept mine in the following manner:
First, I cut a 12''x6'' rectangle from a sheet of foamboard. From the bottom left and right corners I measured 3.5'' up, and cut from that point to the centerline of the top edge. To hinge the elevator, I cut through the paper only 1.5'' from the bottom of the (now) pentagon. Break the rest of the foam along that cut by folding the elevator over. The same applies to the rudder.
Cut a 6''x 6'' rectangle. From the top edge, measure 2.5'' over and cut from this point to the opposing bottom corner. Then, as before, cut through the paper only and break over the rudder.
Attaching stabilizers to the Fuselage:
I used hotglue to adhere the horizontal stabilizer first, being careful to recess the horizontal stabilizer further past the fuselage, to keep the elevator out of the way of the back end of the stick. The rudder is simply glued to the top of the horizontal stabilzer, lined up perpendicular to the fuselage stick and down the centerline of the horizontal stabilizer. To avoid the elevator hitting the rudder, I cut a small triangle from the rudder to allow the surfaces to freely move.
There are two ways to do this. The first is more adjustable but requires more hardware (another set of two bolts/nuts) and the second requires copious amounts of adhesive.
I used two 3'' strips of the angle aluminum with a 3 degree bend in them to hold the angle of the wing. I used two side-drilled holes in the fuselage to rubber band the wing to the plane. The advantage to this is that the wing is removable for transport. If this is not an issue, you can use method 2:
Attach two small 7'' rectangles of foam with hot glue to the sides of the fuselage where the wing is to be positioned. Then, glue these to the wing .25'' from the centerline on each side.
Step 3: Mounting Servos and Assembling Linkages
This process begins with cutting appropriate lengths of wire for pushrods. I started with a 7.75'' length for the rudder and a 8.5'' length for the elevator. The difference in length is in order to skew the placement of the servos so that the control horns do not interfere with one another. I made Z-shaped bends at 90 degrees in each end of the wire. It is much easier to use linkage stoppers in the surfaces' control horns to avoid having to make an exact bend, but should you want to avoid these additional costs, more care is needed. The outcomes of each method are identical.
If your servos are not centered, now is the time to connect electronics and center them up. Make sure this is done before gluing in servos, or they might need excessive trimming to neutralize the surface positions.
To attach the control linkage horns to the surfaces, simply use hot glue. This could be built more robustly with screws, but this method is robust enough for the plane to fly. Once the linkages are attached to the surfaces, the control rods can be inserted into the centered servo horns. Now the servos can be hot-glued to the sides of the fuselage. For best bond strength, use an exacto knife to score the side of the servo prior to gluing. Apply the glue to the side of the servo, then position it on the stick fuselage to the point where the surfaces are neutral.
This process can be made more scientific by looking at the cad and measuring out the rods/ positioning the servos properly, but this method is much, much faster.
Step 4: Alternative Linkage Methods
A cheaper control horn can be made from a popsicle stick, broke propeller, used gift card, etc.
To do this, simply cut a .25''x .75'' rectangle and drill an appropriately sized hole .125'' from one end. Cut a .25'' slit in the paper where the control horn is to be mounted, fill it with hot glue, and insert the horn until it reaches the other paper side. Easy!
Step 5: Landing Gear and Electronics Mounting
The front landing gear strut is made from the aluminum stock in the BOM. Bendj .5'' from one end to a ~100 degrees and cut 6'' from this bend. Twist the last .5'' of this end so that is perpendicular to the rest of the front landing gear strut. Drill a hole of the size necessary for your wheel's bolt through the center, and attach the bolt with a nut. Loctite in another bolt over this one, add the wheel, and loctite a bolt after.
The rear landing gear is built exactly the same way, except there is another 6'' length for the second wheel.
The advantage of a stick plane is the ease of mounting electronics. All of this plane's electronics are mounted underneath the wing, ziptied to holes in the fuselage. Make sure to keep these holes small as to not severely weaken the fuselage. One strip of velcro is postioned directly under the motor mount block to correctly balance the plane with the battery. A hook and loop strap can be attached around the fuselage and battery to solidify this joint.
Step 6: Surface Throws/ Flying!
Elevator:10 degrees up/down
Rudder:25 degrees left right
Flying this plane is almost hands off, as the wing provides way more lift than necessary. If your radio has the ability, I suggest mixing in some down elevator with higher throttle, because it does tend to pitch up when accelerating to higher speeds.