Toki's SmartServo RC-1 uses Shape Memory Alloy (no motor) 
Thursday, November 8, 2007, 04:26 PM - Flying Contraptions
The Toki Corporation in Japan has a new type of micro servo for micro R/C flying contraption. The new servo doesn't use a motor or regular actuator (electromagnetic or piezo), it uses shape memory alloy wires that the company calls "biometal".

The SmartServo RC-1 has the following specs: dimensions: 38x9x3mm, weights (with wires): 1.03g, torque: 15 g.cm, consumption: 10 mA, 0.15 W, deviation angle +- 30 degrees, operating voltage: 3 to 5 V.

The good news is that the servo is available for sale at Air Midi Micros for $32. The AMM web site has a video showing the servo in action. The technical documentation for the servo is available from Aair Midi Micros and from Toki.

Technical data about the material is available in this PDF document.

The servo apparently measures the resistance of the wire to estimate the position of the horn. Hence, the wire serves not only as an actuator, but also as a sensor (the control circuit is shown here).

Many moons ago (circa 1994), I built a micro R/C airplane with Nitinol wires from RobotStore to control the rudder. It wasn't a success, because the Nitinol wires took way too long to cool down after "contracting". The cooling time was roughly 1/2 second. Toki seems to have solved the problem, though their documentation says that the servo slows down (and the max deflection angle is reduced) after a period of continuous use.

RobotStore sells Toki's helical BioMetal wires.



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16g Ornithopter from Tech. U. of Delft 
Saturday, November 3, 2007, 11:32 PM - Flying Contraptions
The DelFly II is a radio-controled ornithopter with an on-board camera built by the University of Delft.

The specifications are quite impressive: 16 grams, 1.6g outrunner brushless motor, 130mAh single-cell LiPo battery, autonomy: 8 minute of hovering, or 15 minutes of horizontal flight, 15 m/s max speed, -0.5 m/s min speed,
30cm maximum dimension, electromagnetic actuators for elevator and rudder control. They also claim video-based trajectory stabilisation, target recognition, and such (see the second video).

There are photos, and movies
here, and here.

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New Li-Ion Batteries from A123 charge in 15 minutes 
Monday, October 8, 2007, 12:18 AM - Flying Contraptions
Battery manufacturer A123 Racing is offering a new type of Lithium-Ion batteries for model cars and airplanes that can not only put out enormous amounts of current, but can also be charged in 15 minutes.

A123 Racing is a sub-brand of manufacturer A123 Systems, who has been producing the new type of battery for a while. They were so far mainly used in rechargeable cordless drills.

The so-called Hypersonic cell has the following characteristics: capacity: 2300 mAh; nominal voltage: 3.3V; internal impedance: 10 milliohms; max continuous discharge: 70A (30C); burst discharge (10 seconds): 120A (60C); fast charge current: 10A (4C), which translates into a charging time of 15 minutes; mass: 70 grams; price: $20.

A 3S1P pack costs $90, and the special charger is roughly $100.

The energy per gram is not as good as a LiPo, but you can't beat the charging time....
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Paparazzi: Free / Open Source Autopilot Project 
Friday, May 18, 2007, 01:49 AM - Flying Contraptions
Paparazzi is an open source hardware/software project whose goal is to provide a complete autopilot system for UAVs.

The Paparazzi project is hosted at the "Ecole Nationale de l'Aviation Civile" (ENAC) in France, and is the basis of ENAC's autonomous UAV project.

The hardware is built around a Philips LPC2148 ARM-7 chip. It includes a GPS and Pyro-electric infrared sensors for pitch and roll angle detection (no gyros).


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Crespiere 2007 
Friday, May 18, 2007, 01:25 AM - Flying Contraptions
Crespiere 2007, an annual get-together of electric R/C airplanes in France, took place last week. I'm told the weather was sub-optimal (very high winds), and the turn out less than usual (because of the weather). Web magazine RC Pilot Online has a picture gallery of the event.

I was intrigued by this weird-looking plane that looks like a Calder scultpure.

There is also a picture of my dad's new CAP-10 . Unfortunately, bad weather prevented test flights before Crespiere, hence it didn't fly during the event.


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Nice Electric UAV video from Trek Aerospace 
Tuesday, April 3, 2007, 01:26 AM - Flying Contraptions
Trek Aerospace has demonstrated a small, electric powered UAV called the OVIWUN. It has two contra-rotating ducted fans on each side of a "fuselage". The ducted fans can be independently tilted forward or backward to control yaw and pitch (as well as forward/backward translation). Roll is apparently controlled by changing the relative speed of the rotors. Each rotor is powered by a 450 Watt electric motor. The UAV is 36cm tall, 65cm wide, 41cm long, and weighs 2520 grams (with batteries). They claim an endurance of 20 minutes, and maximum speed of 75km/h (which I find very hard to believe).

The $15,000 price is a bit steep for something many of us could probably build in our shop. However, the good news is that UAV is controlled by an Xscale-based single-board computer running Debian Linux, and comes with open source flight control software.

There is a nice video of the OVIWUN's indoors test flights

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Tech reports on the 2006 UAV competition 
Monday, March 19, 2007, 01:00 AM - Flying Contraptions
This page has a collection of papers by the participants of the 2006 student competition of Unmanned Air Vehicles. There is quite a lot of details about the hardware used in each of the participants' planes.
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Wowwee's R/C Dragonfly 
Sunday, March 18, 2007, 11:28 PM - Flying Contraptions
My friend Jeff Han recently went to the TED Conference and brought back one of Wowwee's new Flytech R/C Dragonflies. I tried it out and took a few close-up pictures.

The dragonfly flies quite nicely. Its control system is somewhat unique: it has a small propeller on the tail (spun by a pager motor) to pull the tail to the left or to the right. It has a "beginner" mode and an "expert" mode. In beginner mode, the Dragonfly turns rather sluggishly, but in expert mode, it is quite maneuverable. However, it loses a lot of altitude in tight turns, so flying in cramped spaces takes a little bit of practice.

There are 4 wings, but they actually are rigidly attached in pairs. The pairs oscillate in opposite phase as shown on this picture.

The LiPo battery is recharged in 25 minutes (probably not to full capacity) by plugging the Dragonfly into the transmitter. A magnet hods it still on the transmitter.




More pictures are available here.

The Dragonfly is available from Radio Shack for $50.00

UPDATE: Doug Setzer points us his DragonFly forum, and to this photo series that shows the innards of a dissected DragonFly.

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Reflex Helicopter from SpinMaster/AirHogs 
Thursday, March 8, 2007, 10:46 PM - Flying Contraptions
SpinMaster came out with the Reflex R/C Helicopter. Like many recent toy R/C helicopters, the reflex has two contra-rotating rotors for stability. The new twist is that it has two "thrust" motors and prop (one on each side of the body) to make it move forward, backward, and to rotate. They claim an un-precendented maneuverability, which I can believe. It has to be easier to control than the Picoo-Z and AirHogs's own Havoc.

The price is $70.


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More R/C sensors from EagleTree 
Saturday, March 3, 2007, 05:50 PM - Flying Contraptions
EagleTree Systems just rolled out a bunch of new sensors for their MicroPower E-Logger system. The E-Logger can record a number of quantities in a flying airplane, such as motor current, RPM, battery voltage and temperature, etc. The new sensors include: altitude (with better than 1 meter resolution), airspeed, and servo current.

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Servo-Free control in cheap R/C plane 
Sunday, February 11, 2007, 07:28 PM - Flying Contraptions
In the last couple of years, a deluge of ultra-low-cost ready-to-flay R/C plane seems to have engulfed toy retailers. Because servos are the most expensive part of R/C planes, most cheap planes have multiple motors and use differential speed control to control turns.

The Air Panther, available at R/C Trading Post uses a different idea: a small propeller inside the vertical fin. I remember reading about this idea many years ago in the "Cloud 9" column in the now defunct magazine R/C MicroFlight. Now, you can buy a ready-to-fly plane for 35 bucks that uses it.


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Micro Turbines operational in 6 months? 
Sunday, February 4, 2007, 09:54 PM - Flying Contraptions
The Future of Things has a story about MIT's micro turbine project. The goal of the project is to produce turbines that are a few mm in size using the same technology used to produce integrated circuits.

Prof Alan Epstein, who has been leading this research for about 10 years, expects an energy density of 500-700 Watt.hour/kg in the near term, and 1200-1500 W.h/kg in the longer term. This includes the turbine and the fuel supply. The energy density for current Li-ion batteries is about 120-150 Watt-hours/kg.

He says commercial versions producing 10 to 50 Watts could appear in 3 to 5 years.

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Air Midi Micro: Micro RC Equipment 
Sunday, February 4, 2007, 09:54 PM - Flying Contraptions
Air Midi Micros sells Micro R/C equipment from Slovakian manufactrurer Microinvent. They have Gasparin/Potensky motors, including geared pager motors, 4g outrunner brushless motors, magnetic actuators, brushless ESC, and receivers. Not cheap, but worth a look.



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Super Cheap RTF R/C Drenalyn 
Tuesday, January 30, 2007, 06:23 PM - Flying Contraptions
The Drenalyn is a popular indoor R/C design in France (I built many such planes myself, see here, here, and here).

It was only a matter of time before a Chinese toy company would produce a low-cost ready-to-fly version. I actually approached the Air Hogs people a few years ago with the PMAV concept, but they were not interested.

Chinese R/C toy company Hongxin Toys is selling a Drenalyn-like R/C toy, which they call a "Kite Airplane". The widget is available in the US from Geeks.com at the incredibly low price of 70 bucks (complete, with transmitter, battery, and on-board LEDs for night flying!).

Most low-cost R/C toy planes are boring 1 or 2-axes types (without ailerons), but this one has elevons, and is probably fully aerobatic.



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Francis Plessier: Pioneer of Unusual Miniature Flying Contraptions 
Tuesday, January 30, 2007, 05:57 PM - Flying Contraptions
You probably figured out by now that we are fond of flying pancakes at Yann's Techno Toys. R/C plane builders have long built fun planes with low aspect ratio or circular wings. The first example I ever saw was Plessier's "Soucoupe", a circular wing built by legendary French modeler Francis Plessier in the mid 1970's. Plessier flew a Soucoupe (with a smiley face painted on the bottom side) at the annual Cirque des Cigognes in Bretigny. I built my first Soucoupe in 1975, right after seeing his. Francis Plessier always came up with crazy ideas for the "Cirque", such as a flying dog house (below), a flying iron (below), flying lawnmower, and many others. His ideas have been ripped
off (often without proper credit) by airplane kit companies in the US.

Pictures of Plessier's Soucoupe, Iron, and Dog House are available at this page.



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Electric Helicopter Beginner's Guide 
Saturday, January 20, 2007, 02:46 PM - Flying Contraptions
This UK site has an excellent tutorial on electric helicopters by Toshiyasu Morita. The tutorial is available in English and French.

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