Last July, the Zephyr (Airbus sites never use the "8") had its first test flight, starting on July 11 and completing virtually 26 days of flight (25 days, 23 hrs, and 57 mins). The novelty is that the super lightweight (unmanned) aircraft uses photovoltaic cells and batteries to drive its two low power engines. That means it should be able to fly for an essentially unlimited amount of time. It flies well above the weather, even extremely intense thunderstorms ordinarily top out a few miles below 70,000 feet, so it can recharge all day then use the stored power overnight.
Zephyr is designed to offer capabilities that fill a gap and complement the roles filled by satellites, UAVs, and manned aircraft by providing long-term local satellite-like services. Applications include maritime surveillance and services, border patrol missions, communications, forest fire detection and monitoring, or navigation, often summarized as ISR (Intelligence, Surveillance & Reconnaissance).The batteries are the novel technology here, but don't seem to be "world beating" in specific energy, offering 435 Watt*hours per kilogram (Wh/kg). Current best-in-class numbers I've heard of for lithium batteries run in the vicinity of 900 Wh/kg, but what can be done in the lab is different from what can be done in the highly conservative world that Airbus demands.
The Zephyr, with the persistence of a satellite and the flexibility of a UAV, flies in the stratosphere at an average altitude of 21 km/70,000 feet. The ultra-lightweight weighs just 75 kg/165 pounds and has a wingspan of 25 meters/82 feet (Fig. 2). Payload is approximately 2.5 kg (5.5 lb.). The only civil aircraft to operate at this altitude was the supersonic Concorde, and the military U2 and SR-71 Blackbird reconnaissance aircraft. The powerplant consists of two custom permanent-magnet synchronous motors rated at 0.60 hp (0.45 kW) each. [BOLD Added: SiG]
[T]he batteries, [are] provided by Amprius Inc. Their silicon-anode technology was originally developed at Stanford University and uses silicon nanowires in the negative side of a lithium-ion battery instead of the conventional carbon. (For more details on this technology, see “Stanford Start-Up Amprius Aims to Mass Produce High-Energy Lithium Ion Batteries” in Scientific American.)
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(Amprius won’t divulge its Zephyr-related battery-capacity and weight numbers due to their “proprietary nature.”) [Note: edits in brackets [] by me - SiG]
Airbus' sales page on the Zephyr includes some missions they foresee for the little aircraft. With a payload of 5.5 pounds, it doesn't strike me as a particularly versatile aircraft, but I must be looking at this all wrong. I can't imagine Airbus designing an aircraft without several target missions in mind, including the required payload and duration.
You can squeeze a digital repeater into that weight, which will work fine for comms, and probably get a camera or three and transmitter in the same weight range.
ReplyDeleteSurveillance is probably the role craft like these will fill. Satellites have a known time period for observation that can be avoided. Powered flight is of limited time duration. Something like this can keep an eye on an area 24/7 for days. And being so small it probably has a tiny radar signature so only the most astute and capable Air defenses will see it.
ReplyDeleteDan nailed it. But as far as Airbus designing an aircraft "without several target missions in mind, including the required payload and duration", look no further than their A380 for the fallacy of that statement. At least as far as the existence of enough customers for that target mission to justify the development costs. But then when you are "Government Motors", you don't have to justify development or production costs, do you?
ReplyDeleteMy problem is that when I think of Airbus or anyone in the business I tend to think of the people I've worked with. The engineers I've met have all been reasonable people. I couldn't see them throwing away money and effort, but you're right that they're Government Motors of the Air, or the low altitude Ariane Space. The top of brass of either one is rather different than the engineering crews.
DeleteIt's also possible it was a learning exercise to stretch their ability to make zero carbon aircraft, and you know that's extremely important to their funding sources.
I agree with you guys that they must have applications in mind. With a payload that small, the only one I can see as practical is a repeater; it can't carry an imager useable from that height, or a worthwhile sigint package. I'm sure that at this point it is a proof of concept and a testbed for technologies that can be used at lower altitudes.
ReplyDeleteI suspect they can use what they have learned at 70,000 feet and apply much of it at 30,000 or lower.
The US has tech that can read license plates from orbit. I have little doubt they also have effective surveillance tech that can be used on these lightweight aircraft.
DeleteThe tech I know of that could do that weighs considerably more than 5 pounds. Sure, 70,000 feet is much lower than those satellites orbit so a smaller telescope will work, but a rough, back of the envelope calculation says it needs a 20" diameter mirror. The main mirror and secondary mirror can't be more than about 3 pounds, to leave weight for structure, computer and radio. I sure don't know how to make a 2-1/2 pound 20" mirror.
DeleteI agree. The spy satellites with high resolution that we hear about are generally considered "bus sized" objects; a large chunk of that size is required for focal length and mirror size.
DeleteThe optical systems I have dealt with for unmanned aircraft, while shrinking in size and getting lighter, are still well above 5 lbs for aircraft operating at 3,000 feet. As SiGB says, physics limits how small the optics can get for any given resolution.
The top of brass of either one is rather different than the engineering crews.
ReplyDeleteI suspect every large human hierarchy follows the same pattern. Most of the workers are normal middle class personalities. The leaders are abnormal sociopaths and psychopaths. There are exceptions: Sam Walton. John Bogle. Hewlett, Packard, many of the early commercial electronics leaders. The rate of leaders with normal empathy would be a great number to know. Ron Paul is 1 in 500.
Humans inherited instincts from the great apes to organize into this particular arrangement. Unlike great apes groups which have 100 members, human groups can have 100 million members. The size of this tax base increases the power of the leaders too much. I don't think these instincts can be removed by any sort of conditioning, but their effects can be muted by diligent work at rational thought.
Technology growth increases the military power of individuals faster than it does groups. Individuals defending against organized crime ("taxation", "regulation") is going to keep getting cheaper and easier. This removes support from the logistical tail. Soon organized crime will no longer pay, because it will cost more to collect than it takes. This has already been the case in mountainous regions since forever. At that point the tail will be chopped off. Millions will freak out and join cults because their political instincts, starved of a charismatic war leader chief monkey, will go out of regulation and tell them the sky is falling. There will be no zombie apocalypse mad max starving time, because government shrinking uncovers economic opportunities faster than it dismantles monopoly services. Who here wants to found an inexpensive hospital, university, or major medical insurance company? The only thing stopping you is the politicians you choose to obey.
Doesn't quote an airspeed but it's got to be low. I wonder how well it will be able to maintain station.
ReplyDelete- Don in Oregon
I suspect they chose a region and season where the winds aloft were relatively low. I also strongly suspect that the aircraft loses altitude overnight and regains it in the morning; other long endurance designs I've read about publically assume it will happen and there is no reason to think this is different.
DeleteConsidering it's less than 2 HP at the props, how quickly do you think it could get on station? 0 to 70,000 feet in 24 hours? Spends the whole day climbing to altitude and the night sinking?
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