More of the amazing detail on Rob’s Halberstadt is evident in this rear quarter photo.
albeit a large one. Make no mistake howev- er, smaller models are much more difficult to build and detail accurately: a 1⁄16-inch er- ror on a large model is just noise; on a small model, it’s a skin thickness. Also, my hot buttons for WWI era aircraft are the tires and pilot, as I can make just about every- thing else. If you can’t get something com- mercially that is close, it gets incrementally harder to do. You’ll find “vital” stats of the model in the At A Glance box.
The design The model was designed in DesignCAD
2D using three-views contained in Windsock Datafile #27, Halberstadt CL.II. My stan- dard procedure is to scan the three-views and trace them using Corel Draw Trace which can output in a .DXF (vector) format. Scanning yields a “bitmapped” image and I then have Corel trace and output the image in a vector format, so what I wind up with is an image having vector lines that are blocky and ragged. This is where it gets a little fun with out-
AT A GLANCE Type:
Construction: Wing span: Wing area: Length: Weight:
Wing loading: Prop:
lines since I then retrace the model by hand once the image is imported into CAD. Nev- ertheless, if the three-view is good, the scanned image gets me very close. From here, I draw in reference lines and then loft the bulkheads along with all the other re- lated parts, all the while thinking of how the thing is going to go together. I also design all the parts to interlock as this is lighter, stronger and reasonably idiot-proof. A primary goal on this model was to have
R/C 1 ⁄9 Scale
balsa and ply 46.5 inches 534 sq. in. 32 inches 56 ounces
15.1 oz./sq.ft. 10-7 APC
Motor: Turnigy SK3542-1000 outrunner ESC:
Castle 36-amp
Battery:Thunder Power 2250 mAh Li-Po, 11.1v, 3s, 45C
Radio: FLYING MODELS 4 channel
no visible R/C equipment and so it was help- ful to have all the R/C equipment on hand so I could tailor the parts to the equipment. At this point, I had already done my homework on MotoCalc to determine what I need for propulsion. When possible, I try to use the prototype’s access panels for radio equip- ment access and I also consider how to keep this stuff out of the way of scale details such as a full cockpit or scale engines. In this case, Halberstadt was kind enough to locate an access panel directly under the cockpit area which I used to hide all three servos. Another convenient area for R/C equip-
ment is in and around the motor compart- ment since provisions have to be made to get to the flight battery. Here, I made a mold for the removable upper cowl which provides access to the flight battery, ESC, receiver and motor. The mold also incorporated the
cockpit surround since I wanted a scale thickness here. There is just nowhere to hide in a WWI model. Generally, the model is fairly convention-
al in its design with the primary materials used in construction being birch and poplar plywood along with balsa, carbon fiber, alu- minum and fiberglass. It got a bit interest- ing in the tail however, as there was just no room for a stab that would go through the end of the fuselage, the latter needing also to incorporate the fin, the sprung tail skid and the control linkages. Breaking some “new ground”, I decided
that carbon rods going through aluminum tubes housed in the tail and in the stab would be the way to go. Aside from being lighter, this setup is seriously strong and en- abled me to finish the fuselage and tailplane separately. I used a similar arrangement for the wing panels, incorporating a very slight amount of dihedral to avoid the droopy dog- ear look. While the wings look simple, they had
their own alligators. I wanted a close to scale infrastructure due to the fabric covering. Since I figured that Halberstadt knew what it was doing on the original, I also felt that, with the wings being so thin, I had better think ahead and make provisions for func- tional rigging, anchored by handmade brass fittings. These were screwed into ply plates securely embedded in the wing structure. Once the wings are covered the game is pret- ty much over, so all the strut and rigging points have to be designed in beforehand. The upper wing’s center section was par- ticularly challenging as I wanted to install a scale-like radiator that can be seen through and that resides below the surrounding sur- face of the wing. Mounts for the cabane struts had to be incorporated also, the upper rear of which are only millimeters outboard of the scale aileron torque rod control horn openings. Since the CL.II had an inverted “V” rear cabane with the forward cabanes coming from the cowl to the extreme forward corners of the center section, I could not use a traditional “N” strut to locate and level everything while under construction. To solve this, I nevertheless made an “N” strut to locate the center section, the forward part of the “N” being cut off once the forward ca- banes were installed. I made the landing gear from carbon tube, a plywood laminate and steel wire that
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