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The Millennium Falcon

Dennis Weatherly takes a look at this high performance sailplane manufactured by New Creations R/C. The Millennium Falcon is a real sweetheart. If you can handle basic epoxy-glass, wood, and foam construction, you can build this model, and if you are looking for a first high performance electric sailplane, this might just be the plane.

Splash

Stats:
  • Span: 84 inches
  • Area: 640 sq. inches
  • Airfoil: SD7037
  • Weight: 64 ounces, as reviewed.
  • Wing Loading: 14.4 oz/ sq. ft.
  • Power System: Aveox 1412/2Y, 10 x 1700 SCR cells
  • Power Loading: 150 watts/lb.
  • Number of channels: 3 to 5 (ailerons and flaps are optional)
  • Skill Level: Intermediate.  Suitable as a first high performance sailplane.
  • Available from: New Creations R/C

 

Back at the 1996 KRC, between onslaughts at the New Creations R/C booth, Kirk and I discussed my desire to build an electric-powered sailplane. I didn’t want a 7-cell, 2-meter floater, but I couldn’t afford an F5B ship either. Kirk recommended his own Millennium Falcon kit. After a bit more discussion it sounded like a good match, so a deal was struck.
The Millennium Falcon is a 7-16 cell electric sailplane. The fuselage is large enough to accommodate anything from a geared 035 to an FAI40. The Schuemann style wing planform spans 84 inches and packs 670 square inches of wing area. The airfoil is the SD7037 that is very popular with the sailplane crowd. The stock kit is a polyhedral, rudder/elevator model. An insert in the instruction manual provides some input on adding ailerons and/or flaps.

Kit Contents

The kit box that arrived was pretty substantial in size. Digging through the packing material revealed a pretty complete kit, including:
  • a very nicely molded epoxy-glass fuselage with integral fin, rudder, and T-tail mount.
  • white foam wing and stab cores pre-sheeted with obechi (the deluxe kit includes pre-sheeting).
  • the minimal balsa and ply needed to complete the airframe.
  • all pushrods and links, many of them already pre-bent to shape with Z-bends at the servo end.
  • construction notes and drawings (there are no full size plans except for the rudder).

Also in the box were a few extra bits that I had added to the order (and which you may want to purchase also):
  • a nice, machined epoxy-glass motor mount.
  • an Aeronaut carbon fiber 12x7 folding prop with the proper size spinner and a +5 degree yoke for added pitch.

 

Construction

Construction begins with the wings and stab. Balsa leading edges and tips are glued in place, and then carved and sanded to shape. Set the stab aside at this point, resisting the temptation to cut loose the elevator. The wing has five pieces: a flat center section, tip panels, and small tiplets. At this point, you need to decide whether you want a 2-channel polyhedral model or if you intend to add ailerons and/or flaps. If you intend to have servos in the wings then be sure to make the wire channels in the wing panels before they are joined. I had told Kirk that I would use ailerons, so he had already drilled out the wire channels for me. You can do this fairly easily with a long piece of brass tube mounted in a drill or by heating the end of a long piece of piano wire and melting the wire channel into the core.
Robbe aileron mounts worked out great.  They require a 2-inch hole to be routed in the foam core, and then the mount is glued in place.  Aileron horn was made from fiberglass PCB material.
Sand in the appropriate angles at each root and tip rib, and then epoxy the panels together. I chose to modify the recommended dihedral angles to more closely match models like it in my area. I ended up with five degrees between the center and tip panels and zero degrees between the tip and tiplet panels. The center-to- tip panel joints are reinforced with two inch wide glass cloth and epoxy, while the tip-to-tiplet panels get a 3/4 inch wide tape. Once cured and sanded, cut free any control surfaces you intend to use on the wing and cap the cutouts with balsa or obechi.
If you plan to have a movable rudder then you can dispose of the epoxy-glass one in the kit and build the balsa version. All of the wood needed was provided in the kit, and was high quality, lightweight stock.
The fuselage needs minimal construction. Thoroughly wash the fuselage to remove any mold release. Fasten the motor mount to the motor, and then slide this assembly into the fuselage. Fit a spacer to the back of the spinner (I used thin cardboard stock) and then mount the spinner on the motor so it is snug against the front of the fuselage. The proper down and right thrust is already molded into the nose. When satisfied with the fit, tack glue the motor mount into place with 5-minute epoxy. Then remove the motor and spinner and build up a solid glue joint around the mount. I used 30-minute epoxy with milled fiberglass fibers added to increase the strength.
All that’s left on the fuselage is to epoxy in the wing bolt plate and build the rudderpost. This was my first model with the servos mounted in the fin, but the instructions were quite clear about how to proceed. Just be sure to run the servo extensions and tape the connectors before you glue the rudderpost/servo mount assembly into place! For the aileron servos I used the Robbe aileron servo mounts that Kirk recommended. These require a 2-inch hole to be routed in the wing. I glued the mounts into place with polyurethane glue. The servo drops into two rails and is secured by the mount cover, which also has an integral pushrod fairing. Very clean!
The next steps cover fitting the wing and stab. The wing saddle on my model required some careful grinding with a Dremel before the wing would fully seat in the saddle, but the final fit is quite good. A single 1/4-20 nylon bolt holds the wing trailing edge in place. I added a small half circle of 1/16” plywood here to spread the loads out over the obechi skin. The front of the wing is held down by the fairing on the fuselage. A hard 1/4 inch square balsa stick is trimmed to fit snugly between the fuselage sides near the wing leading edge and then glued to the wing to keep if from shifting side-to-side. I was uncomfortable about this, but left it alone.
Once the wing is mounted you can fit the stabilizer. It is bolted to the top of the fin with 6-32 metal screws. I had to trim the saddle a bit from side-to-side to get the wing and stab parallel. The plans call for one degree of negative incidence in the stab, but my stab mount had two degrees. I went with this anyway rather than carving up the stab mount. I had a heck of a time using my Robart incidence meter on the stab because I had already cut the elevator loose. If you wait to do this until after the stab is mounted then the incidence meter is much easier and more accurate to use.
After mounting the stab you can finish up the pushrods at the stab and fin. The fuselage seam required very minimal filling and sanding and then it was time for painting and/or covering.
I elected to paint my model to try to keep the weight down and to allow me to be creative on the color scheme. The fuselage was shot with one coat of Krylon primer, and then sanded smooth. I hated this primer! It clogged up the sandpaper very badly, requiring almost three full sheets of 220 grit wet-or-dry (used dry) to finish the job. On the other hand, the white, yellow, red and black Krylon enamel went on just fine from the spray can and glossed nicely.
For the obechi covered parts, I applied three light coats of Flecto Diamond Finish water-based Varathane. This stuff is nearly odorless, nearly non-toxic and fills quite well. It does tend to run easily so you have to be careful when brushing it on. Disposable foam brushes seemed to work best. I sanded each coat lightly before applying the next. After the third coat had dried overnight I sprayed the yellow, red and black trim with Krylon enamel and it adhered well to the varathane underneath.
Inside the fuselage, showing the 10-cell 1700SCRC pack, Aveox controller and the barely visible Hitec receiver.  Not seen here is the 600 mAh battery mounted above the motor controller and inside the wing fairing.  There is a lot of room in here as all the servos are mounted elsewhere!
Since all of the servos are mounted during construction there is very little left to do at this point. I mounted a 7-channel Hitec receiver way back in the radio compartment, underneath the wing trailing edge. The direct drive Aveox 1412/2Y and controller had their wires shortened severely and soldered together to eliminate a potential failure point. I was expecting in excess of 60 amps current draw, so I didn’t want to take any chances! A 600 mAh NiCD radio battery is Velcro mounted to the wing fairing, just ahead of the wing leading edge and above the motor controller. The 10-cell 1700SCRC pack just barely fits between the motor and the receiver, with the motor controller sitting on top of the motor battery. All of this stacking was necessary to get the CG at the proper point, in part due to the strong, but slightly heavy pair of Hitec HS-85 servos I had mounted in the fin.
The wing center section showing the hard 1/4" square balsa stick that centers the wing leading edge between the fuselage sides.  Fiberglass patch around the aileron wires is to reduce splitting of the thin obechi.  Also visible is the minor damage to the wing leading edge caused by the first hard landing.  Note that this is a good spot to put your name and address (which we've digitally scrubbed from this photo - ed).


The business end, showing the Aeronaut 12x7 carbon fiber folding prop, +5 yoke and 40 mm spinner.  The whole assembly was perfectly balanced from the factory.
Ready to fly weight came in at 64 ounces, or 4 pounds. I was a bit disappointed in this, as the plans suggest a finished weight around 55 ounces. Maybe my paint job wasn’t so light after all! The plans called out the rudder and elevator throws, but neglected to mention aileron throws, so I set them to where they looked "about right", about 3/8" each way. I used the computer in my Airtronics Module transmitter to set up 50% differential on the ailerons, 50% rudder to aileron mixing and spoilerons (both ailerons go up) for landing. I could not get the side slider to operate the motor controller properly, so I ended up putting the motor on the landing gear switch. Motor tests showed 68 amps current draw at 8700 rpm.
The completed airplane

Flight Performance

Test flight day dawned clear and full of thermals. It was also the local sailplane club’s summer picnic and fun fly, so I had a crowd around to witness the first flight. A range check showed plenty of range, with the motor on or off. With the motor run by the gear switch, I would have to throw the model left-handed. I elected to have someone else do the throwing on the first flight. I held my breath, nodded to the launcher, hit the motor switch, and off it went.
Wow! I had never flown a sailplane like this before. I was expecting a good climb, but what I got was far beyond my expectations. The nose wanted to pitch up under power so I had to hold a bit of down elevator with the power on. In five or six seconds, it was at winch launch height. At eight seconds, I shut the motor off and settled the model into a glide. Handling was really good, although a little more aileron differential would be nice. Thermal turns are easy to maintain and the model is very stable. It stays where you put it in a thermal and just flies around and around. It also loops and rolls nicely.
I tested the spoilerons at altitude and was surprised to see the nose pitch UP when I deployed them. I tried to keep this in mind when landing, but the first arrival was a bit "firm". No damage to the model, except that the wing leading edge under the fuselage fairing was beat up a bit. I may replace this section of LE with spruce or basswood for a bit more strength.
I dialed in some down elevator trim under power and when the spoilerons are raised, recharged the pack after it cooled and launched again. I threw it myself this time, with my left hand. I didn’t have to worry about getting the model up to flying speed - it leapt out of my hand as soon as I hit the power switch. The climb is nearly hands off now. I shut the motor down after five seconds and went thermal hunting. Two climbs and twenty five minutes later I landed due to tired eyes. On the third flight, I handed the transmitter around to some local hot-shoe thermal pilots. Everyone was impressed with the ship. We eventually made six climbs to altitude on this one charge and still had a bit of power left over.

Recommendation

The Millennium Falcon is a real sweetheart. If you can handle basic epoxy-glass and wood/foam construction, you can build this model. If you are looking for a first high performance electric sailplane then I can highly recommend this one.

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