Instrumentation • Electronics
we prefer numerically cut foam, which makes for a lighter, more efficient structure. We then support the wings with a carbon fibre spar, so the current process we favour most is a selective laser sintering (SLS) laser printed fuselage with foam wings linked together by carbon fibre tubing.” Southampton’s latest generation UAV is designated the
Mark V airframe with a 20 kg maximum takeoff weight, rapid prototyped structure and ultra-light foam core aerodynamic surfaces on a wingspan of four metres. It boasts a 5 kg payload and 12 hour endurance from a twin cylinder four stroke petrol engine with on board start and 6/12V generator. Auto take-off and landing is supported by on-board GPS and camera systems, with fully redundant dual circuit avionics. “You do not need the same strength in wings as you do for
a fuselage,” Keane contends. “The trouble with printed nylon is the minimum thickness of about 1mm, which is too much material so wings are heavier than they need to be. By cutting foam, we can make the wings larger because they carry an evenly distributed load. “If you laser sinter a wing, because of its minimum wall
thickness it will have more weight than a foam wing, unless you are building a larger aircraft with a wingspan of perhaps as much as ten metres, at which point you cannot print in nylon because the printers are not big enough.”
Next generation propulsion
Muir disputes Keane’s contention that foam is the best wing material, arguing that foam unsuitable if anything is to be stored inside wings and that those on the EADS UAV is designed to hold the next generation of propulsion systems, which can be distributed in the wing profile. “Most UAVs either use electric or petrol propulsion,” reasons Muir. “Ours uses the former, currently with lithium polymer
Fig. 4. Body parts for KOR EcoLogic’s Urbee were produced on a Stratasys 3D printer.
“In order to manufacture the UAV from the polyamide material we used, we had to beef up the structure and the static prototype was produced at 1mm wall thickness, whereas the actual design the students came up with is designed to use substantially thinner walls from a material that is less flexible in order to maintain the same weight characteristics.” ●
New generation of high performance confocal measurement technology
C
onfocalDT 2451 and 2471 are the latest high performance controllers
in Micro-Epsilon’s confocal measurement range. Due to excellent signal-to-noise
ratio, measurement rates of 10kHz are achieved using an LED and 70kHz using a xenon light source. For the first time, a high performance CCD array is installed as the sensor element in the controller, developed by Micro-Epsilon in a robust industrial housing. The active exposure regulation of a
laser line enables rapid, precise surface compensation in dynamic measuring processes on a range of different target surfaces. ConfocalDT is the first controller that offers Ethernet, EtherCAT, RS422 and
The controller also offers specific calibration options during thickness measurements. As a result, significant improvements in measurement results can be achieved. The confocalDT controller operates using a passive cooling system that minimises fan noise and interference. All confocal sensors from Micro-
Epsilon can be connected to the confocalDT2451/2471 controller. Both standard sensors with fixed lenses
analogue output interfaces. The sensors are therefore extremely flexible and can be easily integrated to existing systems. The user can remotely configure
measurement channels using the intuitive, web-based software via Ethernet. This means it is not necessary for the user to install any other measurement software.
and miniature 4 or 8mm diameter sensors in axial or radial designs, can be used with this controller. ●
Enter 19 or ✔ at
www.engineerlive.com/ede
MICRO-EPSILON Messtechnik GmbH & Co. KG is based in Ortenburg, Germany.
www.micro-epsilon.de
www.engineerlive.com 19
batteries but we are researching the use of hydrogen fuel cells, which provide substantially more power for less weight. Our UAV was sized to take advantage of several materials and technologies coming up on the horizon.
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