|Jun 04, 2011, 10:37 PM|
Building a Decathlon - part 4
Now we're ready to finish the model!
First up - coating the tail and wing with white glue.
Part 12: coating lifting and control surfaces - 1h
Use 30-40% diluted weldbond (or other white glue), and apply to ALL lifting surfaces, flowing out to even the coating. On the tail, be mindful not to get glue in the hinges of the control surfaces.
I usually apply two coats to the wing, esp. on the outside edges where the wing may be subjected to touching the ground on a bad landing, or during a tight turn to avoid an obstacle. Before application to the wing, attach the strut clevices with some CA, and then flow white glue out over the upper and lower wing body - INCLUDING the centre sections. I use a Qtip to dab additional glue around the clevice mounts to strengthen them.
Let dry overnight or at least 8-10h to ensure a good cure before applying any decals. Add additional glue coating after 2h to elevator leading/trailing edges and top of rudder.
Part 13: Decals, gear install and CG test - 30-60 minutes.
Start with applying decals to taste, rubbing out any bubbles. Once applied, then attach the gear. I prefer the Dubro 1.75" foam lightweight wheels over the stock landing gear and pants, because the wheels roll better on both asphalt and grass, and give a bit of extra nose clearance as well. If you opt for this, the stock gear hardware may be used, with some small washers on either side of the wheel to ensure smooth rolling, and some lock nuts on the inside strut to secure wheels. Affix after tightening with some CA to avoid
loosening during landings.
Before putting the wing on, put the propeller and nose nut/spinner onto the shaft's collet. Tighten securely. I color match mine with the same yellow spray paint as the gear struts and let dry while assembling everything else.
Use a small piece of dowel or rod to fit inside the interior under the wing mounts to check CG, and place battery unconected into the compartment. CG should be right about at the immediate rear of the battery cage, or right near the upper portion of the wing curve (highest point of winge camber). If too nose or tail heavy, adjust by adding a nut into the cowling post, or use 7g (1/4oz.) weights inside the body bottom to get CG close to ideal. It can be 1/4" or so forward, but avoid having it too far back, or the plane will fly less stable.
Affix wing onto the plane by inverting the wing and place the model onto it. Use strut mount screws to initially adhere wing, then flip over and attach rubber bands.
That's it! You can check everything before flying (throws, trim neutralization, propeller tracking/alignment, etc.) and you're ready to fly! I use a MAS 8x6x3-blade FG reinforced nylon (Nitro type) propeller on my plane, and it flies great!
I just returned from a 2 flight maiden on this new plane - flew very true and square. I added a 7g weight about 3" back from the servos, and the plane flies nicely. It is just a teeny bit tail heavy, but it handled moderate breezy conditions just fine without stalling. This is deliberate, as the newer batteries I use (1000mAh 20C Lipos) are just over 50g vs ~40g for stock cells. This will bring the CG back to near ideal under nominal flying situations. Empty weight of this new model is 420g, or just shy of 15 Oz.
While this plane is a definite favorite of mine, the assembly suggestions here can be used on many models that use foam (such as micro Champs, and other types with Z-foam). I have mentioned many times about the benefits of white glue on foams, and GE use in many portions of an airframe.
I hope that this series was of use to many who wish to improve the robustness and performance of their models in general, and many Parkzone Super Decathlon owners may od their planes after seeing this.
Smooth and steady skies!
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