HIGH-ALTITUDE PSEUDO-SATELLITES (HAPS) – A QUICK REVIEW

Airbus Zephyr production line via AB Jul18 lower-res

At the recent Farnborough Airshow, my personal highlight was a visit to the Airbus Zephyr production facility (above), in the nearby Science Park. I wrote about this for AIN here and, as predicted, this fascinating solar-powered design has since claimed a new endurance record for an aircraft – more than 25 days.

The Zephyr project was started at Farnborough in 2001, and was sold to Airbus Defence & Space by QinetiQ in 2013. But apparently, satellite provider EADS Astrium (a predecessor of Airbus D & S) had already invested in the project, when it needed more money.

Meanwhile, the US government funded similar efforts, such as Pathfinder, Helios, Solar Eagle and Vulture. None led anywhere, but in the last few years there have been advances in in solar cell and battery technology, and miniaturisation of payloads. In the US, IT giants Facebook and Google both funded solar-powered HAPS in recent years, with the ambition of filling the gaps in worldwide internet coverage. Surprisingly, perhaps, both projects have foundered, but back in the UK, some former Zephyr pioneers have developed a rival design named PHASA (Persistent High-Altitude Solar Aircraft). BAE Systems has invested in their company, named Prismatic.

Questions remain. Is there an optimum wingspan/payload ratio? Are all the flutter problems solved? What is the best way to climb and descend these delicate airframes through turbulent air to the calmer conditions of the stratosphere? Can a ‘constellation’ of them be successfully connected by laser communications? Will their role as loitering imaging platforms be challenged by the proliferation of small satellites offering ever-decreasing revisit rates at much lower cost and much higher resolution than previous spaceborne imaging systems?

Solar-powered airships are an alternative, theoretically offering greater stability and payloads. Again, though, some US projects burned through a serious amount of taxpayer’s money in the last decade. Remember HiSentinel, HALE-D and ISIS, all now abandoned? There are fabric and thermal management issues. The only current airship project appears to be the Thales Alenia Stratobus, due to fly in 2021. However, the Italian Aerospace Research Centre (Italian acronym CIRA) believes that hybrid airship would be best, and it showed a model at Farnborough.

For the moment, Airbus is clearly leading the way, with a real customer for the current Zephyr S (the UK Ministry of Defence) and a larger-payload version (Zephyr T) coming next. Airbus has even designed a multi-mode radar imaging system for Zephyr-T, weighing just 20kg.

However, a more prosaic means of filling the internet communications gap is already in service. The high-altitude balloons of Google’s Project Loon have proved their worth over remote locations in Africa, New Zealand and elsewhere, and as emergency substitutes for damaged ground base stations during the Puerto Rican hurricane disaster last year. The project employs massive computational power to accurately model the winds in the upper atmosphere so that the positions of these balloons can be adjusted through control of the gas volume. Their payloads are solar-powered, but they don’t rely on batteries to stay at 65,000 feet.

LATEST MH370 REPORT AVOIDS THE OBVIOUS

The Malaysian-led team investigating the disappearance of flight MH370 for ICAO has issued a new 450-page report into what has become the greatest aviation mystery of all time. There’s not much new, except for the first official release of data found by the Royal Malaysian Police on the flight simulator that Captain Zahari kept at his home.

This simulator contained seven waypoints that approximately coincide with the known diversion of MH370 westward into the Strait of Malacca, then northwestward to the Andaman Sea and then south into the Indian Ocean. Why then, did the lead investigator Kok Soo Chon declare at a press conference this week that the loss of MH370 could not “have been an event committed by the pilot”? The report itself makes no such statement. But on page 379 it does say that the three unexpected turns that placed the B777 on course for a watery ending in a remote ocean “are difficult to attribute to any system failures. It is more likely that such manoeuvres are due to the systems being manipulated.”

Most independent investigators concluded long ago that the circumstantial evidence linking Zahari to the disappearance is too strong to ignore. I explored this evidence in various articles for Aviation International News in 2015, notably this one. Since then, it has become clear that the ACARS reporting system as well as the transponder and the radios can be turned off from within the cockpit. That left only the Inmarsat SatCom ‘handshakes’ as a means to track the aircraft, other than primary radar returns.

MH370 Penang radar my photo closeup Feb18

The latest report describes the returns obtained by Malaysian military radar in a little more detail than previously. My photo above shows the one on Penang that recorded the last radar trace of MH370 as it headed towards the Andaman Sea.

The report says that despite the 180-degree turn back of MH370 to fly a track along the Malaysia/Thailand border from the South China Sea, with no transponder operating, “the military did not pursue to intercept the aircraft since it was ‘friendly’ and did not pose any threat to national airspace”. Oh, really? It’s much more likely that the air defence operators were not alert to any unusual event in the small hours of the night. Remember, all the analysis of the primary radar returns was done from recordings, some time after the disappearance, which is why the search for MH370 was not switched from the South China Sea for such a long time.

It is most unfortunate that the extensive searches of the southern Indian Ocean have failed to find wreckage. Great work has been done by many experts to try and define the search area from the satellite ‘handshakes’ and log-ons. Most believe that MH370 eventually ran out of fuel at cruising altitude somewhere along the seventh Arc defined by Immarsat, and then descended steeply. But a minority believe that the aircraft was still under control when it hit the ocean. If that is the case, “the search is an almost impossible task”, the former head of the Australian Transportation Safety Board (ATSB) told a 60 Minutes documentary in his country last May.