Saturday, August 19, 2017
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FLY RC Airshow

Breaking The 1/2-gram Barrier Twice



Regular Fly RC readers will recall the microflight milestones achieved by Martin Newell of San Jose, CA. We reported in the February 2006 issue that Martin was the first to break the 1-gram barrier for an electric radio-control model. At the 2006 NEAT Fair, Martin was at it again with his .695-gram models; the first under 700 milligrams.
As you can see, Martin is not one to stop once he has achieved a goal. Driving onward, he continued to optimize every component to reduce the weight even further. A few weeks ago, Martin ducked under another barrier that few thought could be breached. His latest model, the Shark, tips the scales at less than 1/2 gram or, more precisely, 495 milligrams (mg). He has two versions of the Shark, and the lighter one weighs only 485mg. In addition to their sub-1/2-gram weights, the two models feature other unique innovations. Both feature single-phase brushless motors that Martin hand-built. They consist of a single coil with a magnet mounted on a .010 carbon-fiber prop shaft running in stainless- steel hypodermic bearings. The motor is controlled by the tiny Allegro 1442 chip. Martin forms propellers of his own design out of lightweight carbon fiber and epoxy over Delrin forms he machines with a CNC-equipped Sherline mill.



The Newell Sharks are the first electric-powered radio-controlled planes to weigh less than 1/2 gram and the first to use micro brushless motors of this style. The lighter model uses a new 60mg 27MHz receiver from Nick Leichty, while the slightly heavier one uses a 65mg Starving Rabbit FHSS receiver that Martin made and programmed. He demonstrated this unique receiver at the NEAT Fair with a 960mg model, and its use here makes this Shark the first 1/2-gram model to also have Frequency Hopping Spread Spectrum control. Both receivers are hand-built; in fact, only the batteries are not made by hand, though they have been trimmed to save a few milligrams.


We can only marvel at the dedication and perseverance required to accomplish such a staggering goal. At this point, the batteries are the real limiting factor. At 295mg, the batteries account for about 60 percent of the models’ weights. No doubt, Martin is already hard at work on a solution to this, and we can’t wait to see what he comes up with.


How much is 1 gram?For most people, a gram is a rather hazy measure, too small to be of much practical use and well below the radar in day-to-day life. Consider these examples. A U.S. dollar bill weighs 1 gram and a regular-size Kleenex tissue about 1.4 grams. Thus, 1/2 gram is equal in weight to half a dollar bill or about one third of a tissue. SPECSMODEL: Shark
WINGSPAN: 2.65 in.
WING AREA: 2.84 sq. in.
WEIGHT: 485 – 495mg (.0171 – .0175oz.)
WING LOADING: .87 – .89 oz./sq. ft. LENGTH: 3.3 in.
POWER SYSTEM: 45mg singlephase 35-ohm handmade brushless motor, custom carbon-fiber prop, Allegro 1442 controller, Atomic Workshop 8.5mAh LiPo battery FULL-THROTTLE POWER: .075 amps, .27 watts, 14.2 W/oz., 227 W/lb.
TOP RPM:
25,200
STATIC THRUST:
195mg
DURATION:
1 min. 40 sec. ACTUATOR: 1/16-in. (1.6mm) ID, 135 ohms, 1×0.5mm magnet
AIRFRAME:
.010 CF rod fuselage, .007 CF rod wing and tail outlines MINIMUM FLYING AREA: 20-ft. sq. WEIGHT BREAKDOWN PROP 15mg MOTOR 45mg
BATTERY 295mg
RECEIVER
60mg
AIRFRAME, SWITCH, ACTUATOR
60mg
WIRE
10mg
F-86 SABREThe North American F-86 Sabre was the U.S. Air Force’s first sweptwing jet fighter, its last true “dogfighter” and one of the most successful warbirds in military aviation history. It first flew in 1947 and became operational with the Air Force in 1948, and by the time its last squadron was retired in Portugal in 1980, almost 10,000 aircraft in 20 variants had been produced, and it had flown in the air forces of 24 countries.
The F-86 benefited from German World War II jet fighter development. The Sabre incorporated many technological and design innovations. It was the first jet to have a sweptwing configuration. It was the first to feature a “flying tail” that enables it to maneuver at high altitudes. It also incorporated full-span leading-edge slats to prevent pitch-up. The F-86’s identifying feature was its nose: an open nose inlet that delivered air to the turbojet engine behind the pilot.


Standard armament was six .50-caliber machine guns, three on each side of the fuselage near the nose. Variants allowed it to carry two 1,000-pound bombs, 16 5-inch rockets, or 24 2.75-inch rockets. It had a maximum sea-level speed of 687mph, a service ceiling of 49,600 feet and a rate of climb of 8,100 feet per minute (again, at sea level).


The Sabre was the jet that defined air-to-air combat in the Korean War. Air Force Gen. William Momyer called it “… our best fighter”. The F-86 was superior to the enemy’s best fighter, the MiG-15, in level flight below 30,000 feet and definitely superior at diving speeds greater than mach .95. Sabre pilot Maj. George A. Davis Jr., who racked up 14 victories, was awarded the Medal of Honor when, in 1952, he and his wingman flew to the defense of a group of fighter-bombers being attacked by 12 MiG- 15s. Capt. Joseph McConnell, with 16 victories, became the world’s first jet triple ace. And America’s top ace in the European Theater of Operations in World War II, Col. Francis S. “Gabby” Gabreski, scored six and a half victories in the F-86 during the Korean War.


Brigadier Gen. Chuck Yeager, USAF (Ret.), a World War II ace and test pilot who was the first to break the sound barrier, said of the F-86, “I dearly loved the Sabre, almost as much as I enjoyed the P- 51 from World War II days. It was a terrific plane to fly.” Dwight Jon Zimmerman


EDITOR’S COMMENTS

The judges at the 2007 WRAM show in February justly awarded this model first place in Electric Scale, where I was honored to see it. In midsummer, I had the pleasure of getting together with Rob Caso again and actually flying his incredible creation. I was anxious, but Rob’s Bulldog is surprisingly well behaved even though it retains the speed and agility expected of a Golden Age racer.


The Bulldog has plenty of power to get out of the grass, and it looked fantastic carving steeply banked high-G turns at speed. It didn’t show any tendency to tip-stall or snap-roll in full racing trim or at a reduced-power cruise, yet it’s nimble enough for sport aerobatics. I caught my breath and returned to straight and level after flying a series of loops, aileron rolls and snap rolls, spins and inverted flight without a hitch. It cruises nicely on partial power, allowing you to significantly extend your air time between charges.


Mindful of the outcome of its first flight, I kept a little extra speed on final and flew it into the flare before pinning the skid into the turf with full elevator. My reward was a smooth landing, and it remained upright throughout the rollout. If the Bulldog intrigues you, a query to Rob through his company, Turn Key RC, will get you info about an upcoming laser-cut kit and accessories. I’ll meet you in the line! Thayer Syme