FLIGHT TEST: RPM TURNBUCKLE

Dec 14, 2011 No Comments by

Hotshot fun-fly champ!

Danny Luchaco from Sayre, PA, shows off his electric-powered “Buckle” at the Kingston Father's Day fun-fly.

Over the years, one of the most popular fun flyer airplanes found at the Kingston Model Aircraft Club's Father's Day Fun Fly has been the Turnbuckle. Events like the Roops (roll and loops), spot landings, and the “Can Can”-tethered soda can target drop, all add to the fun and excitement of this fun-fly competition. Whenever you check out the standings during the weekend, the Turnbuckle always places very well. Thanks to Steve Luchaco, Scott and Skipp Turner, Rolly's Performance Models is now producing a kit of the high-energy Turn-buckle. A very active member of the Kingston Ontario Club, ever since he got his laser cutter, Rolly has wanted to get into the kit business and I was lucky enough to obtain a kit from Rolly. Let's start building!

SPECIFICATIONS

  • Model: Turnbuckle

  • Manufacturer: Rolly's Performance Models

  • Distributor: Rolly Siemonsen (rollys@cogeco.ca)

  • Type: Sport – Fun-Fly/Competition

  • Length: 46.5 in.

  • Wingspan: 59 in.

  • Wing Area: 735 sq. in.

  • Weight: 5.5 lb.

  • Wing loading: 17 oz./sq. ft.

  • Engine req'd: .40 – .55 2-stroke; Electric Motor: E-flite Power .46

  • Radio Req'd: 4-channel (rudder, throttle, aileron, elevator)

  • Price: $75

UNIQUE FEATURES

The engine mounts neatly on a 45 degree and the right side fuselage half is cut for clearance.

The center wing joint is cut on a table saw. If you don't have access to one a dihedral jig template is drawn onto the plan.

The Turnbuckle is sold as a “short kit,” and its contents are neatly packed and clearly labeled. Some of the building materials and hardware must be obtained separately and Rolly provides an “items required” checklist. Also included is a CD with all the building instructions and plenty of excellent photos to guide you. Downloadable instructions are also available at krcm.org under the “Construction Articles” link.

The kit is a relatively quick and easy build. Construction starts with the fuselage and all laser-cut components fit together perfectly. The horizontal and vertical stabilizers are then assembled and set aside for later. The engine (I used an ASP .52A) is mounted at a 45-degree angle so the right fuselage side requires some trimming for muffler clearance. Alignment marks are provided if you plan to use a different motor mount, or prefer an upright engine. I used epoxy on the forward bulkheads and then wrapped the whole fuselage with rubber bands. Once properly aligned, I glued in the rear bulkheads with CA. The landing gear and tailwheel attachments, and adding triangle stock to the forward bulkheads for reinforcement come next, followed by sheeting the fuselage bottom. Pushrod guides and servo rails are installed next in preparation for radio installation followed by sheeting the top of the fuselage.

The wing panels are built over the plans and then joined together. Be sure to extend all the wing spars past the center ribs to allow for the wing joining procedure. All ribs except the center rib are fitted into place on the bottom spar and then the upper main spar and two trailing spars are put in place and then glued with thin CA. Add the leading edges and trailing edge spars and you can glue the top wing sheeting in place. I partially installed the shear webbing, flipped the wing panels over and finished sheeting the bottom. I then completed the sheer webbing and the aileron servo bays between the third and fourth wing ribs and finished up by adding the trailing edge, cap strips and wingtips. For added strength, I reinforced the joint with 6-inch wide fiberglass tape. Complete the ailerons and it's time for covering and final assembly.

After covering all the parts, install the horizontal and vertical tail surfaces. I used carbon-fiber tubes in place of the wing and fuel tank hold down dowels. I also used a formed aluminum landing gear instead of bending the gear from music wire. Once the engine and fuel tank are installed, the Turnbuckle is ready for final set up and balancing.

HIGHLIGHTS

  • ⊕ Easy kit build

  • ⊕ Great fun-fly performer

  • ⊕ Excellent quality


IN THE AIR

Father and son team Doug and Colin Geisel have flown their Turnbuckle at the Kingston Fun-Fly for years.

I went to the Simcoe Model Aircraft Club's field for the first flight. After the preflight checks, I was ready to go. I quickly advanced the throttle, and with virtually no roll out, the Turnbuckle was airborne and climbing. I had an ear-to-ear grin as I heard one of my fellow pilots comment, “Whoa, that wasn't a takeoff—that was more like a launch!” After a few circuits, I tried out the high rates. This is where the Turnbuckle really shows its stuff. I enjoyed the first fight, it easily handled anything I threw at it. I soon realized that the Turnbuckle is only limited by pilot skill.

GENERAL FLIGHT PERFORMANCE

  • Stability: The Turnbuckle is stable at a wide range of speeds. It is very easy to fly and landings are a breeze.

  • Tracking: The model has excellent tracking, even inverted flight is hands off. The large control surfaces are very responsive and keep the Turnbuckle heading where you want it. The oversized landing gear gives the model excellent prop clearance and ground handling.

  • Aerobatics: The Turnbuckle is a very capable aerobat. With its oversized ailerons it performs anything you want, including a lot of 3D manoeuvres. With the CG set properly spins are spectacular.

  • Glide & Stall Performance:The model glides exceptionally well and stalls are very predictable. With a slight headwind, the Turnbuckle will slow to almost walking speed.

PILOT DEBRIEFING

The Turnbuckle is a really great all-around flyer. It took very little stick time to be comfortable with it. It flies well at a very wide range of speeds, and for a performance model, its low-speed handling characteristics are fantastic. Landings are very predictable and with a little practice, the Turnbuckle can be put “on the contest spot” without a problem.

CONCLUSION

I equipped my Turnbuckle with five Futaba S3004 servos. There's no recommended control throws listed, so for the test flight, I set all surfaces initially to ¾-inch throws and 20 percent expo. I'm quite happy with the model and have only made a few changes since. The Turnbuckle is truly a fun-fly competitor. It is perfectly suited for fun-fly competition, is an overall excellent sport flyer and would be an excellent addition to any modeller's collection.

Canadian Section

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