内容来源：https://www.geekwire.com/2025/radical-full-size-prototype-stratospheric-drone-first-flight/

内容总结：

美国西雅图初创企业Radical公司近日宣布，其研发的"Evenstar"全尺寸太阳能无人机原型机已完成首次试飞。这款翼展达36.6米（超过波音737）、重量仅109公斤的无人机，采用车顶低速起飞方式，在俄勒冈州特许无人机测试区完成了低空飞行测试。

该无人机目前依靠电池驱动，后续型号将配备机翼太阳能阵列，目标实现在距地20公里高度的平流层持续飞行数月。公司创始人团队来自亚马逊Prime Air项目，已获得逾450万美元融资。其研发的"平流层卫星"概念旨在以低成本替代部分卫星功能，承载33磅有效载荷，可应用于高清成像、应急通信、气象监测等领域。

尽管空客、软银等企业也在布局平流层太阳能无人机赛道，但阿尔法贝特、脸书等科技巨头曾折戟同类项目。Radical公司CEO詹姆斯·托马斯指出，近十年来电池能量密度翻倍、太阳能电池成本下降90%，以及人工智能技术的进步，终于使该领域迎来突破临界点。目前团队正基于试飞数据优化设计，计划明年启动高空测试，推动"空中持久基础设施"从概念走向现实。

中文翻译：

总部位于西雅图的Radical公司宣布，其全尺寸太阳能无人机原型机已完成首次试飞。这家初创公司正致力于将机器人飞机送入平流层执行长期军用与商业任务，此次低空飞行标志着计划迈出了第一步。

"这款飞机翼展达120英尺（约36.6米），重量仅240磅（约109公斤）。"Radical首席执行官詹姆斯·托马斯对媒体表示，"它的翼展比波音737略大，重量却只比常人体重稍多。可说是工程学上的极致突破，我们为团队取得的成就深感自豪。"

上月进行的飞行测试选址于俄勒冈州蒂拉穆克无人机测试场，这是美国联邦航空管理局指定的无人驾驶航空系统测试基地之一。托马斯未透露本次飞行的具体时长与最大高度，仅确认属于低空飞行。

"我们从车顶实现起飞，起飞速度非常低——在地面或低空区域飞行时速刚超过15英里（约24公里）。"他补充道（后续说明所用车辆为斯巴鲁，笑称"这算是太平洋西北地区的特色选择"）。

本次原型机仅依靠电池驱动，未来机型将在机翼加装太阳能阵列，实现65000英尺（约19812米）高空持续飞行数月。为模拟平流层飞行所需的太阳能板与电池重量，工程师在测试机上加装了配重。托马斯预计高空测试将于明年启动。

托马斯与联合创始人兼首席技术官西里尔·诺特布姆均来自亚马逊Prime Air无人机项目团队。两人于2022年中期离开亚马逊创立Radical，迄今已获超450万美元融资。此次全尺寸无人机测试之前，该公司曾在2023年完成13磅（约5.9公斤）缩比原型机超过24小时的连续飞行。

公司制造基地设于西雅图巴拉德社区。托马斯透露团队现有六名成员及一位新入职员工："我们始终保持精干架构。要让这类飞机实现突破，必须在电子系统与空气动力学追求极致效率，团队运作同样需要高效模式。"

谈及商业前景时，托马斯表示已获得潜在客户关注，但拒绝透露细节："我们正与政府机构和商业团体展开合作。这项技术的应用场景涵盖影像采集、通信传输、气象预报等诸多领域。目前阻碍客户服务落地的关键因素是尚未实现产品升空，这正是我们全力攻克的方向。"

被命名为"Evenstar"的太阳能飞机属于高空平台站（HAPS）类别。研发团队更愿称其为"平流层卫星"，因其能承担许多人造卫星的典型任务，同时规避航天器发射的高成本与复杂性。潜在应用包括：难以被攻击的侦察视角、通信受限区域的信号中继、气象模式监测及大气研究等。

"不少客户期待借此提升对地球天气系统与气候的认知能力，这个应用方向令我们倍感振奋。"托马斯说。Evenstar可搭载最高33磅（约15公斤）有效载荷，他解释道："根据主要应用场景分析，这个载重足以容纳高带宽直连设备无线电通信系统，或超高分辨率成像设备。"

目前多家企业竞逐平流层长航时太阳能飞机领域，包括AeroVironment、软银、BAE系统、Swift Engineering、Kea Aerospace、韩国航空航天工业公司和NewSpace Research & Technologies等。空客"西风"号太阳能无人机曾在2022年以64天续航创下平流层飞行纪录，最终因坠毁终止任务。 Alphabet于2016年关闭泰坦航空航天公司，脸书则在2018年放弃天鹰座项目，均折戟于此领域。

托马斯指出，过去十年间高空太阳能飞机领域已迎来转机："关键支撑技术取得长足发展。十年间商用电池能量密度翻倍，太阳能电池成本降至十年前的十分之一，加上计算能力与人工智能的进步，使可行性模型终于成为现实——若按十年前的参数计算，根本无法达成技术闭环。"

在他看来，Radicle的理念已不再显得激进："不仅理论模型证实可行性，实测飞行数据也与模型吻合。这项技术既能实现设计目标，又能释放空中持久基础设施的潜力。我理解为何众多机构投身于此——这并非新概念，而是人们长期渴求突破的领域。如今我们正处在终于迎来曙光的临界点。"

英文来源：

Seattle-based Radical says it has put a full-size prototype for a solar-powered drone through its first flight, marking one low-altitude step in the startup’s campaign to send robo-planes into the stratosphere for long-duration military and commercial missions.
“It’s a 120-foot-wingspan aircraft that only weighs 240 pounds,” Radical CEO James Thomas told GeekWire. “We’re talking about something that has a wingspan just a bit bigger than a Boeing 737, but it only weighs a little bit more than a person. So, it’s a pretty extreme piece of engineering, and we’re really proud of what our team has achieved so far.”
Last month’s flight test was conducted at the Tillamook UAS Test Range in Oregon, which is one of the sites designated by the Federal Aviation Administration for testing uncrewed aerial systems. Thomas declined to delve into the details about the flight’s duration or maximum altitude, other than to say that it was a low-altitude flight.
“We take off from the top of a car, and takeoff speeds are very low, so it flies just over 15 miles an hour on the ground or at low altitudes,” he said. (Thomas later added that the car was a Subaru, a choice he called “a Pacific Northwest move, I guess.”)
The prototype ran on battery power alone, but future flights will make use of solar arrays mounted on the plane’s wings to keep it in the air at altitudes as high as 65,000 feet for months at a time. For last month’s test, engineers added ballast to the prototype to match the weight of the solar panels and batteries required for stratospheric flight. Thomas said he expects high-altitude tests to begin next year.
Thomas and his fellow co-founder, chief technology officer Cyriel Notteboom, are veterans of Prime Air, Amazon’s effort to field a fleet of delivery drones. They left Amazon in mid-2022 to launch Radical and have since raised more than $4.5 million in funding. September’s test of a full-size drone follows up on the 24-hour-plus flight of a 13-pound subscale prototype in 2023.
The company’s manufacturing operation is based in Seattle’s Ballard neighborhood. There are currently six people on the team, plus a new hire, Thomas said. “We’re still lean,” he said. “To make this airplane work, it has to be really efficient, right? Really efficient electronics and aerodynamics. And you also need a really efficient team.”
Thomas said Radical has attracted interest from potential customers, but he shied away from discussing details. “We’re working with groups in the government and also commercially,” he said. “Obviously there are applications at the end of this that span everything from imagery through telecommunications and weather forecasting. There are a lot of people really interested in the technology, and the thing that stops us from serving those customers is not having a product up in the sky. So, that’s what we’re working through.”
Radical’s solar-powered airplane, known as Evenstar, is just one example of a class of aircraft known as high-altitude platform stations, or HAPS. Thomas and his teammates use a different term to refer to Evenstar. They call it a StratoSat, because it’s designed to take on many of the tasks typically assigned to satellites — but without the costs and the hassles associated with launching a spacecraft.
Potential applications include doing surveillance from a vantage point that’s difficult to attack, providing telecommunication links in areas where connectivity is constrained, monitoring weather patterns and conducting atmospheric research.
“We have customers who are really excited about the way that this can improve how we understand Earth’s weather systems and climate,” Thomas said. “That’s an application that we’re really excited to get into.”
Evenstar will carry payloads weighing up to about 33 pounds (15 kilograms). “That was based on analysis about major use cases,” Thomas explained. “That payload is enough to carry high-bandwidth, direct-to-device radio communications, or to carry ultra-high-resolution imaging equipment.”
Radical isn’t the only company working on solar-powered aircraft built for long-duration flights in the stratosphere. Other entrants in the market include AeroVironment, SoftBank, BAE Systems, Swift Engineering, Kea Aerospace, Korea Aerospace Industries and NewSpace Research & Technologies. Airbus’ solar-powered Zephyr set the record for long-duration stratospheric flight in 2022 with a 64-day test mission that ended in a crash.
Among those who tried but failed to field stratospheric solar drones are Alphabet, which closed down Titan Aerospace in 2016; and Facebook, which abandoned Project Aquila in 2018.
Thomas said the outlook for high-flying solar planes has brightened in the past decade.
“The key supporting technologies have matured enormously,” he said. “Commercial battery energy density has doubled in that 10-year time period. Solar cells are 10 times cheaper than they were just 10 years ago. And then you have advances in compute and AI, and all of these things feed into the situation we have now, where it’s actually possible to make the models close — whereas when we run the 10-year-old numbers, we can’t close the models.”
The way Thomas sees it, the concept behind Radical isn’t all that radical anymore.
“Not only do our models say this will work, but we have flight data that agrees with our models, and says this is a technology that can serve its purpose and unlock the potential of persistent infrastructure in the sky,” he said. “I can see why other people are pursuing it. It’s not a new idea. It’s one that people have wanted to crack for a long time, and we’re at this critical inflection point where it’s finally possible.”