Hobby King Sunbird Build log

Transcription

1 Hobby King Sunbird Build log The Sunbird is a neat kit, with quite a clever interlocking design and a very elegant wingplan reminiscent of the classic Bird of Time. In theory, the design will force all parts into alignment but only if you are totally accurate in your cutting, sanding and fitting without a plan you must rely on your own alignment methods building board edges, rib-squares, T-squares etc. if you are to have a reasonable chance of building a flyable air-frame. CA adhesives are recommended, but I am building my second Sun Bird using epoxy and PVA the CA gave considerable alignment problems and consistently flooded the wingspar, which makes the joining process very difficult (lots of blind filing if you want to get an accurate fit. Wood quality seems quite good and die-cutting is accurate. The downsides are: No plan included Minimal assembly instructions unclear at best, misleading at worst. Laser-cut parts un-identified On the other hand, the kit represents outstanding value for money compared with many other kits on the market and builds into a model of which you can be proud. Where you can - make accurate photo-copies of the balsa sheets just so that you have a parts guide for when Mr. Murphy strikes and you need to cut a new part! Your life will be much easier as the build progresses if you label each part with the part numbers given in the instructions but be extremely careful identifying wing ribs the instructions are not at all clear on certain ribs. Note also that the wing rib web pieces taper from root to tip, so it is vital that you maintain the order of these webs as you assemble the wing. The following notes are an attempt to give future builders an idea of the issues that I have encountered so far, and will hopefully form a basis for those more experienced than me to develop a more professional build guide for this very pretty airplane.

2 Hardware Label balsa items as best you can.

3

4 Tail feathers very easy just pop out and assemble flat Assembling the tail feathers is pretty straight-forward. Just note that the spacers need to be cut from the raw stripwood supplied, and you should be careful to get the angles as close to perfect as you can otherwise the joints will be too weak.

5 Move on to the fuselage. Lay out the components and ensure that you are building one right side, one left side. Use the sheet balsa in the kit to estimate how far from the edge of the fuselage sides you need to glue the bracing strips. Aim to have the edge of the skin sheet just perfectly aligned and your subsequent joint will have maximum strength and your sanding task will be minimised.

6 Once you have the fuselage bracing strips glued in place, carefully position the formers. Glue all the fuselage reinforcing strips in place, being careful not to make my mistake of mounting A09 above the strip. It needs to be below if using the recommended 9gm servo in order to get adequate clearance under the wing mount.

7 Ensure that each of the three formers are vertical to the fuselage sides before gluing in place. Once the formers are completely dry, you can add the second fuselage side. Once again be extremely careful to align the sides vertically and the formers at right angles to the fuselage sides. Moving on to the canopy, use a similar technique to the fuselage to position the bracing strips and then gluing A07 accurately will be quite simple.

8 Make sure that the canopy sides are at right angles to A07, and then the assembly will be a snug fit and easy to sand to a pleasing profile.

9 I used a couple of ply offcuts from the servo tray to add a little strength to the former and to provide alignment and mounting points for the canopy. Add the servo tray (A05) below the fuselage bracing to ensure that you sufficient clearance for your servo arms

10 and add the ply plates (A04) if you are planning to use the wing bolt mounting method (rather than a horizontal dowel and elastic band knock-off system). Close-up of the correct position for gluing A05 (servo tray)

11 Now we move on to the wing assembly. In theory, the rib web spacers will align the ribs parallel with each other and at right angles to the trailing edge. In practice, use all the aids to checking alignment that you can. The ply capping strips for the main spar make a very strong structure provided that the webs are perfectly aligned and carefully glued. Be careful to make both a left and right half of these wing centre sections!

12 I was careful to clamp the main spar tp the building board in an attempt to avoid any chance of warping when I added the top capping strip Once the spar was completely dry, it is straightforward to offer up the leading edge, pin and then glue in place

13 Note the use of the mini-rib to provide a firm base for the wing root sheeting. Packing under the T.E of the mini-rib with some scrap sheeting makes it much easier to align these supporting ribs.

14 To be continued