Pay-As-You-Use CFD for Small Manufacturers

Small aircraft manufacturers such as Slovenia’s Pipistrel typically cannot afford expensive wind-tunnel testing when developing designs and lack the high-performance computing (HPC) resources that larger airframers use to simulate their products.

Now two European Union-funded research projects are allowing Pipistrel, working with Slovenian software developer XLAB, to access per-pay-use high-fidelity simulation services running on an HPC cloud infrastructure.

Limited to a small in-house computer cluster, Pipistrel is looking for options to increase the fidelity and reduce the calculation time for computational fluid dynamics (CFD) simulations and is a partner in both the Fortissomo and Mikelangelo projects.

Involving 123 partners, Fortissimo is a three-year, €22 million ($23.5 million) European Framework 7 research project, begun in 2013, to provide small and midsize companies with cloud access to HPC simulation services.

Launched in January, Mikelangelo is a three-year €6 million European Horizon 2020 research project to improve the responsiveness, agility and security of the “HPC in the cloud” virtual infrastructure by developing packaged applications.

Fortissimo is focused on computationally intensive high-fidelity simulations that describe the airflow over aircraft more accurately than the simulations typically run by Pipistrel, and has allowed the company to use large-scale HPC for the first time, says XLAB.

Mikelangelo, meanwhile, is enabling Pipistrel to use the cloud infrastructure to run a large number of simpler CFD simulations of the type in now performs in-house. This allows the manufacturer to explore more rapidly a particular aerodynamic configuration under a range of conditions.

Seeing Stars: Using Pulsars for Navigation

Celestial navigation was a mainstay in the early days of aviation, and astronavigation is still used in nuclear bombers to overcome jamming. Now a European research project has shown the feasibility of employing pulsars for aircraft navigation that is independent of ground- or space-based equipment.

The PulsarPlane project is investigating the use of pulsar signals for real-time navigation and timing, to overcome the vulnerabilities of global navigation satellite systems and reduce operating costs for aviation in the second half of this century.

Begun in 2013 and funded by the European Union’s Framework 7 research program, the project is coordinated by the Dutch aerospace laboratory NLR and involves universities in the Netherlands, Finland, Portugal and Bulgaria.

Pulsars are fast-rotating neutron stars that emit stable, fast electromagnetic pulses with unique periods between 1.4 millisec and 5 sec. and unique shapes. Pulsars are visible from everywhere on Earth and across a wide band of frequencies.

The challenges of using pulsars as a navigation source include detecting the extremely weak, dispersed and scattered signals. A radio telescope is needed to detect and characterize new pulsars, but smaller antennas can be used to track known pulsars.

Motivating factors for the project include that using pulsars for navigation requires negligible infrastructure, signals are always available and are wideband, and there are many transmitters visible at any time, making jamming and spoofing difficult.

Problems to be tackled include: fitting a large antenna on an aircraft; finding the minimum antenna size for an acceptable detection time—the smaller the antenna the longer the acquisition time; designing the receiver and signal-processing algorithms; and providing a large amount of onboard processing power.

Unlike GPS, where the position of the satellites is known precisely, the exact location of pulsars is not, but they move at high velocity relative to the Earth. Navigation would use the time of arrival of the pulse, requiring signals from three pulsars for 3-D position, along with an additional signal to remove ambiguity and another for time correction. 

An aircraft navigation system would have a phased-array antenna front end and a navigation back end that would be uplinked, from a ground segment, a pulsar database collected by radio telescopes and a Solar System database.

Using the databases, and with inputs from the aircraft’s inertial reference system and correct time from an atomic clock, the system would determine the pulsar’s direction in the aircraft reference frame. This would be used to update the aircraft’s position.


NASA Armstrong’s ‘Mini-737’ UAV Flies

An unmanned flying laboratory has begun operating at NASA Armstrong Flight Research Center. The twin-jet Ptera has been developed by Georgia-based Area-I as a low-cost, low-risk testbed for advanced configurations and controls.

The 200-lb. aircraft, with an 11.3-ft. wing span, was built with an 11%-scale Boeing 737 as the template. Armstrong says the unmanned Ptera will help bridge the gap between wind-tunnel experiments and crewed flight testing.

Delivered in 2014, the Ptera made its first flight at Armstrong on Oct. 22. The aircraft was flown under both radio control and the control of its Cloud Cap Piccolo autopilot. The Ptera reached a speed of 145 kt., its fastest flight yet.

Area-I has built a second Ptera for NASA Langley Research Center. This is a 290-lb., 12-ft.-span aircraft modeled on the Bombardier CRJ700, with rear-mounted engines, and will be used for T-tail loss-of-control research.


TsAGI Tests Light-Aircraft Fuel from Gas

With aviation gasoline becoming harder to access in remote regions of Russia such as Western Siberia and the Far North, the TsAGI central aerohydrodynamic institute has demonstrated the feasibility of using a fuel made from propane and butane.

Ground tests of so-called aviation condensed fuel (ACF) have used a four-cylinder, air-cooled piston engine representative of those powering most small aircraft. Similar studies have shown the positive results for gas-turbine engines, says TsAGI.

Design changes were made to the piston engine to maintain its operating characteristics using ACF. “During the test, the engine was started without any problem, and it continued to operate properly in all modes,” says TsAGI expert Vyacheslav Zaitsev.

Further experiments are planned, and a flying demonstrator is being designed based on an existing piston-powered aircraft. “These tests should confirm the possibility of modifying current similar aircraft with a dual-fuel option,” the institute says.

Zaitsev says the dual-fuel option will reduce costs for aircraft operators now using expensive avgas, particularly in the remote Far North and similar regions where the liquid natural gas used for ACF production is abundant.


Aeryon Gets Equity Boost for Enterprise UAVs

The flow of funding into the small unmanned aircraft systems (UAS) market continues, with Canada’s Aeryon Labs closing a $60 million investment from U.K.-based private equity company Summit Partners.

Based in Waterloo, Ontario, Aeryon has been operating for nine years and has positioned itself in the “enterprise-grade” small UAS market, providing systems for utility inspection, first responders and the military.

Aeryon’s main product is a SkyRanger quadcopter, a 5.3-lb. vertical-take-off-and-landing UAS capable of 50-min. endurance carrying a high-definition stabilized video camera or customer payload. The company also produces payloads and mission control software.

Aeryon says the equity investment will enable it to build on its “aviation not recreation” approach to small UAS and accelerate its expansion and the delivery of additional capabilities.