Launching at this size is a simple matter, even for an OAP!

Scheibe-Loravia Topaze 1:4.2-Scale

Part II: Completing the Build and Flying

For readers who have not yet done so, you may want to take a look at Part I of this two part series before proceeding.

My wing construction methods have changed in recent years. These are incorporated into the Topaze build, such as 5mm square spruce spars are used for the initial construction in the normal fashion, with ply web plates glued to the front of the spars. Then, slots are retro-cut (a five minute job) and a 5mm square sub spar added in front of the web plates for about two-thirds of the wing’s span. This results in a very strong but light wing and goes a fair way towards keeping the wing loading down. Once the lower D-box sheeting has been added, the wing is set up on its support jigs, weighed down, and the top sheeting added, thus locking it in its final shape.

The flying surfaces are covered with HobbyKing film, with the open structures covered in their recently added matt clear. The fuselage is covered with Solartex, the joints brushed with 2K primer and flatted, and then the whole fuselage sprayed with white 2K primer before finishing off with 2K top coats.

In flight, the Topaze is entirely predictable and vice-free. With up-going ailerons mixed with the airbrakes, industrial quantities of drag become available, allowing spot landings in the most challenging of slope environments.

The drawings in PDF format are available from the Resources section, as are a link to more detailed build photos.

01: With the slots cut out, the sub spar is ready to glue in place.

02: With the 0.8mm ply plates sandwiched between the spars, a string I-beam is produced.

03: Scary bit—the aperture is cut for the airbrake assembly. The TE is supported by the rear airbrake stringer, which also is rendered rigid with balsa web plates.

04: The airbrake assembly is jigged to make the blades equally central before glueing in place.

05: View of aileron servo placement.

06: The wings are retained with old-fashioned No 63 rubber bands.

07: The instrument console is retained with magnets, as is the canopy.

08: View of the tailwheel fitment.

09: View of the mainwheel and fuselage underside.

09: View of the mainwheel and fuselage underside

10: Clubmate and member of the Posse, Motley Crew, displays the Topaze at County Model Flying Club (CMFC). 11: The Topaze at White Sheet Hill with its stablemate, the Gull 3. 12: The Topaze at CMFC with the 5th scale Bergfalke 4 and the electric tug.

14: The model is perfectly happy with mild aerobatics. 15: 15: The Topaze at White Sheet Hill.

16: The Topaze at Win Green Hill

17: Wing plan.

18: You’ve read the articles, now watch the video!

f you have any questions about this or the previous article, please feel free to leave them in the Responses section, below, and I’ll do my best to answer as many as I can.

©2021 Chris Williams

Resources

Finished Aircraft Specifications:

• Scale: 1:4.2
• Span: 3.57M
• Weight: 4.5kg (10lbs)
• Wing Section: HQ3514–12

1:4.2-Scale Topaze Free Plan (three PDFs):

• Fuselage
• Wing
• Tailplane

Detailed Build Photo Gallery

• Coming shortly…watch this space!

All images and drawings by the author. Read the next article in this issue, return to the previous article in this issue or go to the table of contents. A PDF version of this article, or the entire issue, is available upon request.