Thoughts on the new E-36 electric FF event
Louis Joyner <[email protected]>
E-36 Electric FF
Developing an introductory free-flight (FF) event is never easy. The model needs to be simple and inexpensive to attract beginners, yet the performance level must be high enough to excite more experienced fliers.
Vic Nippert and a few other modelers across the country have been working to develop an electric equivalent to the popular P-30 rubber event. An electric-powered P-30 proved to be a bit small for the weight an electric model needs to carry. Increasing the wingspan limit from 30 to 36 inches provides enough extra area to carry the batteries and motor. A wide range of motors, propellers, and battery packs used in RC park flyers are readily available.
Preliminary rules:
- Maximum span: 36 inches.
- Minimum weight: 150 grams.
- Motor run: 25 seconds (with a two-minute maximum flight time).
- Only brush-type motors allowed.
- Maximum battery voltage: 4.8 V.
- Gears and folding propellers allowed.
NFFS President Rex Hinson’s Sparks E-36 design utilizes a Powerhouse 36 wing outline with a rectangular stabilizer. The 180-square-inch wing uses a slightly undercambered airfoil. One of Rex’s two models uses a cut-down fuselage from an F1B rubber airplane; he shortened the motor tube and carbon-aluminum boom to fit the smaller model. His other version uses a simple balsa box fuselage. Power is a GWS motor with a 4:1 gear ratio driving an 8x4 propeller.
John Oldenkamp of San Diego (one of the developers of the P-30 event in the 1970s) is now working on E-36. “The emphasis here has been to make stuff that makes sense, is simple, light, and quick to build,” he said.
John’s eBox 36 features a 6 x 36-inch wing with raked tips, giving a projected area of 212 square inches. The stabilizer is 4.5 x 14 inches. Both surfaces use a single tubular spar, a carbon-rod leading edge, and carbon-capped 1/16" balsa trailing edges. The fuselage is a carbon-aluminum tube; a simple balsa pylon holds the batteries and electronics.
Design and trim notes from John:
- Reduce parts count and glue joints where possible.
- CG: set at about 62% (he suggests between 60% and 65%).
- Wing incidence: 1° positive.
- Motor: 2° right thrust and 7° downthrust.
- Power and glide are to the right.
John feels that a rearward CG, often used with locked-up gas models, can produce a large stall at motor shut-down in a slower-climbing electric model. His experience indicates a CG between 60% and 65% gives an almost hand-launched-glider flip at the top with smooth glide entry.
Rubber Model Plans
Colorado rubber and power flier Don DeLoach has developed new full-size plans for three rubber designs from the 1950s. Two are suitable for the Nostalgia Wakefield event.
Altmann Wakefield (1955, J. Altmann)
- Features a Benedek wing airfoil and multi-spar construction for the wing and stabilizer.
- Wing spars: five 1/16" x 3/16" spars and one 1/16" x 1/8" spar.
- Construction is detailed in the May 2006 NFFS Digest. (For information about the NFFS, visit http://freeflight.org.)
- Don’s modern version uses small magnets to attach the rather large rudder to the stabilizer, making packing much easier.
- Laser-cut wing and stabilizer ribs available for the Altmann model (see pricing below).
Copacetic I Wakefield (Doug Moran)
- Utilizes a single-blade folding propeller and Warren truss fuselage construction.
- Wing and twin-finned stabilizer have sheeted leading edges.
- Don’s plans show Moran’s original 100% CG and a suggested 89% CG based on tail-volume coefficients.
- Suggested motor rubber: 24–28 strands of 40–46" Super Sport rubber (unlubed weight 70–90 grams).
- Don notes Moran’s original motor: 50 inches x 133 grams.
Becker Unlimited (1954, Ted Becker)
- Gollywock-size wing with a 31-inch hook-to-hook distance for a longer motor run.
- Uses a twin-fin arrangement.
Other notes
- Plans are CAD-drawn for accuracy and include original information plus modern notes.
- Don also offers plans for his Nats-winning P-30 Polecat 10 design, which was selected as an NFFS Model of the Year for 2006. It features a full-length motor brace that gives a long propeller run. For P-30, the mandatory freewheeling propeller produces extra drag in the glide; a long run (2,200–2,500 turns) reduces glide time needed to make the two-minute max.
Pricing and ordering
- Altmann Wakefield plans: $8 each (post-paid in the US).
- Copacetic I Wakefield plans: $8 each (post-paid in the US).
- Becker Unlimited plans (smaller design): $7.
- Laser-cut ribs for Altmann model: $15 per set.
- P-30 Polecat 10 full-size plans: $7.
- P-30 laser-cut ribs: $8.
To order, send a check to: Don DeLoach 831 E. Willamette Colorado Springs, CO 80903
You can also email Don at [email protected].
Transcribed from original scans by AI. Minor OCR errors may remain.
