RADIO CONTROL: SLOPE SOARING
Wil Byers, Rt. 4, Box 9544, West Richland, WA 99352
WOW! This month's column is a potpourri of model glider news. Hold onto your hats while we give you the latest from JR — the exciting X-388 radio system — plus news on the Hobby Lobby '93 catalog, Soartech IX, a new kit manufacturer with a 100%-scale Libelle, The Birdworks' new foam sloper, foam-cutting equipment, Obeche skin-bonding tips, Bob Holman's scale plans, and early notice of the 1994 World Soaring Jamboree.
JR X-388 Radio System
JR has built on the X-347 to produce the X-388, a computer radio family configured for the pilot's preferred type of flying: airplanes, helicopters, or gliders. JR offers three different transmitters with switch configurations tailored to each flying type, placing switches and knobs in user-friendly locations. The X-388 retains the ergonomic case of the X-347 and adds ultra-sophisticated programming, 1024 resolution (10-bit), eight model memory slots in nonvolatile memory, and eight channels of control.
Glider fliers will find these programming and functions of special interest:
- Selectable switches for all mixes, allowing combination of mix or preset functions and customization of switch layout.
- Full trailing-edge mixing: flaperons, spoilerons, crow, reflex, butterfly, and drooping.
- Full variable trailing-edge camber, independent of presets, for fine-tuning trailing-edge settings for thermal flight and high-speed passes.
- Six fully programmable mixes for eight channels.
- Trim offset memories permit trailing-edge presets for launch and reflex, eliminating the need to retrim each model.
- Trim include mixing function provides trim mixes for simultaneous trimming and reduces the number of mixing programs needed for multiple mixed functions.
- A three-position switch for preset reflex / neutral / camber trailing-edge settings, useful for different lift or penetration conditions.
- Aileron differential capability.
Receivers and servos:
- NER-649S receiver: a nine-channel micro-receiver, JR's smallest and lightest nine-channel unit. Operates on JR's S-series PCM modulation with 1024 servo resolution, 20 ms response time, and weighs one ounce (28.35 grams). Dimensions: 1.42 inches x 2.00 inches x 0.63 inches.
- NER-236XZ and NER-226X receivers: new mini credit-card receivers (0.55 x 2.06 x 1.43 inches), weighing one ounce, using SMT and JR's ABC&W circuitry.
- NES-3321 servo: high-strength wing servo (60 oz-in torque), lightweight (0.95 oz), durable gear train using "skyscraper" technology, and directional mounting ears suited for wing installation. Proven at high speeds (used in a wing that reached 216 mph).
Contact: Horizon Hobby Distributors, 4105 Fieldstone Drive, Champaign, IL 61821; Tel: (217) 355-9511.
Hobby Lobby — 1993 Catalog
The 1993 Hobby Lobby catalog offers a strong selection of scale RC sailplanes and accessories, including models and items that are sometimes hard to source in the U.S.
Scale models featured:
- Grob 103A / Twin Astir: available in 4.0 m or 3.4 m spans.
- Ventus C: available in 3.4 m or 3.74 m spans.
- Discus: 4.0 m wingspan, 1,162 sq in wing area, wing loading about 18 oz/ft² (heavy for a thermal contest model but typical for scale). Uses Eppler 203, Eppler 195, and Ritz airfoils on their wings respectively.
- Sagitta (slope aerobatic): Fern plastic fuselage, foam wings sheathed in obeche wood. Wing uses Ritz 2-30-12 transitioning to NACA 2415. Specs: 87 in wingspan, 665 sq in wing area, wing loading 16 oz/ft². Controls: rudder, elevator, ailerons.
Accessories of note:
- Releasable tow hooks for aero-towing.
- Graupner spoilers with gate-type operation (effective and well-engineered).
I recommend ordering the catalog to browse their offerings.
Soartech IX
Soartech IX is now available. The Soartech series is an excellent technical resource for the model soaring community.
Topics in Soartech IX include:
- The Use of Wind Tunnel Data in the Design of Radio Controlled Contest Models
- Static Longitudinal Stability with the GROCCO Method
- Fear of the Flying Wing
- On Wing Load Computation
- What Can Be Learned from Paper Airplanes
- Building in Sheeting
Ordering: Soartech, c/o Herb Stokely, 1504 N. Horseshoe Circle, Virginia Beach, VA 23451, USA. Prices: $8 U.S., $9 Canada/Mexico, $10 other countries. Add $1.50 for Priority Mail. All previous issues available.
Dave Hill Custom Models — 100% Scale Libelle
Dave Hill Custom Models has entered scale manufacturing with a 100%-scale H-301 B Libelle kit. The kit is very complete: white gel-coated fuselage, clear canopy, wings sheeted in obeche, ailerons and flaps cut and fitted (unless buyer prefers to finish), control surfaces honed and leading edges shaped. Cover and install radio gear, and you're ready to fly.
Design and specs:
- Airfoils: HQ 3.0/13 center, transitioning to HQ 3.0/12 at the tips (with a 3.0/10 transition noted).
- Wingspan: 158 inches.
- Wing area: 1,025 sq in.
- Scale: 1/4 (length 63.5 inches).
- Weight: ~8 pounds.
- Wing loading: ~18 oz/ft².
Dave's next project: a nearly 1/3-scale ASH-26 with a wingspan near 236 inches.
Price: Libelle offered as an ARF for $425 plus shipping. Contact: Dave Hill, 91-229 Wahine'oma'o Way, Ewa Beach, HI 96706; Tel: (808) 681-0051.
The Birdworks — Rubber Duck
The Birdworks (Steve Hinderks) offers the Rubber Duck, an "Elastic Sloper" — an all-foam, durable sloper designed to be quick to assemble and inexpensive.
Rubber Duck specs:
- Wingspan: 36 inches.
- Wing area: 530 sq in.
- Configuration: flying wing with elevon control and tip plates acting as vertical stabilizers.
Quick assembly steps:
- Glue the wing center section together.
- Glue the fuselage to the wing.
- Glue the tiplets on the wing.
- Press the radio gear into the fuselage (press-fit).
- Hook up and adjust the linkages.
- FLY!
The Duck can be ready in under one hour. Price: $35 plus shipping and handling. Available in multiple colors (hot pink to black). Contact: The Birdworks, P.O. Box 1302, Port Orford, OR 97465; Tel: (503) 332-0194.
Feather/Cut Foam-Cutting System (Tekoa / Center for Design)
At the Pacific Northwest Model Expo I saw Roger Chastain demonstrate the Feather/Cut system (Tekoa / Center for Design). The system is light, easy to set up, includes various box sizes, and has its own power supply to control wire temperature. It cuts tapered wings with minor adjustments and is an excellent option if you want to cut cores without borrowing a friend’s setup.
Contact: The Center for Design, 3219 Canyon Lake Drive, Hollywood, CA 90068; Tel: (213) 469-5584; FAX: (213) 469-3006.
Obeche Skin Bonding (Aerospace Composite Products)
George Sparrow of Aerospace Composite Products shared a reliable method for bonding obeche skins to foam cores without epoxy seeping through.
Process summary:
- Thicken epoxy with thixotropic silica (Cabosil) to a ketchup-like consistency.
- Spread the thickened epoxy on the wing skins using a squeegee or adhesive spreader with grooves (1/16-inch deep).
- The grooves leave a small ridge of epoxy; most epoxy is scraped off.
- Press the skins onto the foam cores or vacuum bag until cured.
Result: a light, strong bond without epoxy soaking through the wood or causing later separation.
Contact: Aerospace Composite Products, P.O. Box 16621, Irvine, CA 92714; Tel: (714) 250-1107; FAX: (714) 250-0307.
Bob Holman — Scale Plans
Bob Holman offers a comprehensive line of scale glider plans across Power Slope Scale (PSS), Modern Scale, and Vintage Scale.
Examples:
- PSS: B-52, D.H. 88 Comet, Avro Vulcan.
- Modern: SZD Jantar I, Pilatus B4, ASW-17.
- Vintage: Breguet Fauvette, Slingsby Kirby Kite, Darmstadt D28 Windspeil, DFS Reiher.
Bob continually adds new plans; you can enlarge or reduce plans for custom scales.
Contact: Bob Holman, P.O. Box 741, San Bernardino, CA 92402; Tel: (909) 885-3959; FAX: (909) 889-9307.
World Soaring Jamboree — May 28–June 4, 1994
Early notice: the first-ever World Soaring Jamboree is scheduled for May 28–June 4, 1994. Organized by a coalition including the Northwest Soaring Society, Portland Area Soaring Society, Seattle Area Soaring Society, Inland Empire Soaring Society, North American Scale Soaring Association, Pro-Am Slope Racers Unlimited, and Tri-City Soarers.
Planned features:
- Nine days of soaring events and festivities.
- Contests: Open-class thermal duration, two-meter thermal duration, slope racing (Unlimited and Limited), PSS slope race, hand-launch thermal, F3J, F3B, Scale Soaring, cross-country races, and record trials.
- Banquet, guest speaker, social events, vendor forum, and technical seminars (details still in planning).
Stay tuned to this and other soaring columns for further information and final schedules.
Airfoil of the Month — HQ 1.0/8
Helmut Quabeck's program (and similar programs like Chuck Anderson's) can generate airfoils by specifying thickness and camber. This month's airfoil, generated with Chuck Anderson's program, is the HQ 1.0/8.
Characteristics:
- Performs very well on slope, used on racers and slope aerobatic models.
- Good penetration and overall speed.
- Can "lay on its back" cruising at high speed (reported to cruise well at ~80 mph).
- Low profile drag and reasonable Cl for low camber.
If you need coordinates for the HQ 1.0/8, send an SASE and I'll provide them, or purchase Chuck Anderson's program: P.O. Box 305, Tullahoma, TN 37388. Program cost: $35; airfoil libraries: $15 each.
Make a fast pass for me, okay? See you in a couple of months.
Transcribed from original scans by AI. Minor OCR errors may remain.
