"Voyeur" hovering drone with counter-rotating rotors 
Tuesday, July 1, 2008, 12:11 AM - Flying Contraptions
Drone manufacturer Lite Machines Inc. has a video of their latest drone called the Voyeur.

It's a cigar-shaped drone, 686mm in length, 63.5mm in diameter, with two counter-rotating rotors, 762mm in diameter. It seems to be using bushless outrunner electric motors powered by a 3-cell LiPo battery.
The total mass is 1.4kg. The cruising speed is 30 knots and the autonomy 30 minutes.

There is a cool video on YouTube

This must be the same Lite Machines Inc. that got started by producing the first gas-powered micro-helicopter many years ago. It used a Cox 0.8 cubic cm motor and had a really clever mechanical system on the tail rotor to stabilize the yaw. This was a kind a mechanical gyro, before the days of cheap and light solid-state gyros.


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Verti4: VTOL electric airplane 
Monday, June 16, 2008, 11:03 AM - Flying Contraptions
The Rencontres Electriques de Crespiere, an annual electric flight meeting took place near Paris last week-end. A particularly interesting design was shown this year: the Verti4. It is the simplest and most successful electric VTOL design I have ever seen. It looks like a fairly conventional trainer-style airplane with four motors on each side of the wing (two in front of the wing, two aft of the wing). The motors can pivot 90 degrees (all together) from facing up to facing forward (V22 Osprey-style), allowing a transition from hovering to translational flight. Is with other quad-rotor contraptions, two rotors turn clockwise, and two counter-clockwise on a diagonal. From what I gather from Jean-Claude and Bertrand (my dad and brother) who attended Crespiere, the stabilization and control is not done with some sort of custom electronics, but with a combination of conventional gyros, and channel mixing.

There are a few videos on YouTube:
video 1,
video 2.
video 3



Others have built quad-rotor or quad-ducted fan electric VTOL planes before (like this F35 or this strange-looking quad-EDF contraption), but not with this simple way of transitioning to translational flight.


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20 gram Piper Cherokee RTF R/C Plane 
Monday, June 16, 2008, 12:48 AM - Flying Contraptions
Kyosho has a series of ready-to-fly R/C airplanes called the Minium that come with a complete 2.4GHz radio set.

Until recently, the only Minium plane was a small Cessna (38cm wingspan, 18 grams). The plane has been available (and very successful) in Japan, Europe and Australia under the Kyosho/Minium name. In the US, a very similar plane (if not exactly identical) has been distributed by Horizon Hobby under the ParkZone brand. It sells for $120

Now Kyosho has announced a new Minium: the Piper Cherokee. The main difference is that the Cherokee has ailerons. The plane is advertised for pre-orders for $180 on Kyosho's US e-commerce web site, but the availability date is unspecified.

What's strange is that the same web site does not have the Cessna (probably because of some exclusive contract with Horizon Hobby).
Even stranger, Kyosho's Japanese website used to have a page on the Cherokee, but it has been taken down....
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DARPA-funded Nano Ornithopter Project 
Monday, June 16, 2008, 12:38 AM - Flying Contraptions
Aerovironment has apparently received 0.5e6 US$ to develop a nano-UAV that flaps it wings. I'm guessing Aerovironment's Matt Keenon (an micro R/C enthusiast and pioneer) must be involved in this project.

It looks like the plane could be designed to take off vertically.
The advantage of flapping wings for hovering is that you don't get a reaction torque, as with a helicopter rotor. The solutions are few: contra-rotating rotors, or oscillating blades (flapping wings).

The mechanical design, the control system, and the aerodynamic efficiency will all be challenging.



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EagleTree's Altitude and Airspeed Sensors 
Monday, June 16, 2008, 12:22 AM - Flying Contraptions
EagleTree Systems have introduced two new sensors to their telemetry and flight recording product line: an altimeter with 1 meter resolution, and an airspeed sensor (with Pitot tube).

They cost around $40 each, and include an 7-segment LED display.
They can run standalone and display the maximum value observed during a flight, or they can plug into one of EagleTree's flight recording systems.

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Plantraco's MicroMAV 
Sunday, June 15, 2008, 11:59 PM - Flying Contraptions
Plantraco (also known as MicroFlight.com) sells a tiny disk-shape plane called MicroMAV that looks a lot like a smaller version of my PMAV: disk-shaped wing, rudder underneath the wing.

The MicroMAV has a 12cm wingspan (my PMAV is 32cm), and weighs a mere 4g. It was designed by Henry Pasquet and Robert Guillot. It uses a single cell 20mAh LiPo, and a magnetic actuator for the rudder (no elevator). You can have it for $90 (plane only) or packaged with a transmitter for $150.

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Plasma-propelled Flying Saucer? 
Sunday, June 15, 2008, 06:49 PM - Flying Contraptions
Science Daily has a piece on a University of Florida professor of mechanical engineering Subrata Roy, who has proposed a design for a flying-saucer-shaped UAV that would be propelled using magneto-hydrodynamics. The basic idea is pretty old: ionize the air around a plane, apply a magnetic field, and inject a current through the ionized plasma. The Lorentz forces will accelerate the plasma. The principle works fine to propel model boats in salt water, but it's horribly inefficient because, although salt water conducts electricity, it has a high resistance. Much of the energy is wasted in the water. In air, the situation is worse.

The article in Science Daily merely mentions a patent, not an actual prototype. Don't hold your breath for a practical prototype...

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In-flight First Person Video Equipment 
Sunday, November 25, 2007, 03:38 AM - Flying Contraptions
The latest trend in R/C flying is First Person Video. This consists in mounting a wireless camera in an R/C airplane, and flying the plane by looking at the video from the camera (generally using goggles).

The ultimate refinement is to mount a head tracking device on the goggles so as to control the pan and tilt of the camera.

A few on-line shops and web sites have popped up to cater to the new population of FPV pilots. One of these web sites is FPV Video.

Shops for FPV equipment include Hobby Wireless, and New Generation Hobbies.

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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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