Diesel Power to Pistons

柴油动力驱动活塞

Up until recently, if your goal was to have a turbine engine under the cowl it meant you had to pony up and invest in a million-dollar-plus aircraft that might exceed your mission and, in most cases, your bankroll. While it’s not a new concept, the emergence of very small, or “micro,” turbines is of great interest, especially these days when fuel costs and availability are on every owner’s mind.

直到最近，如果你的目标是在发动机罩下安装一个涡轮发动机，那就意味着你必须花钱投资一架100多万美元的飞机，这可能超出你的任务，在大多数情况下，也超出了你的资金。虽然这不是一个新概念，但非常小或“微型”涡轮机的出现引起了人们的极大兴趣，尤其是在燃料成本和可用性是每个车主都关心的时候。

Several manufacturers have jumped into what is likely to be a lucrative general aviation market for these microturbines. While the concept of turbine engines remains consistent with all the players, subtle differences between the offerings are present. Before we get into some of the available microturbines, let’s look at what makes an engine a “turbine” and what differentiates the micros from what we know as the “standard” turbine engines widely used today.

几家制造商已经进入了这个可能是有利可图的通用航空市场。虽然涡轮发动机的概念与所有参与者保持一致，但产品之间存在细微差异。在我们进入一些可用的微型涡轮机之前，让我们看看是什么使发动机成为“涡轮机”，以及微型发动机与我们所知的“标准”涡轮发动机的区别。

The Basics

基础知识

The truth is all turbine engines are relatively simple. This also adds to their reliability, as there are far fewer moving parts than in an internal combustion engine, and those parts are, unlike piston engines, rotary instead of reciprocating. Regardless of how they’re producing propulsion, whether it’s driving a shaft with a propeller (turboprop), powering the aircraft with a high-speed exhaust (turbojet), or running an internal fan (turbofan), they share a similar design.

事实上，所有的涡轮发动机都相对简单。这也增加了它们的可靠性，因为它们的运动部件比内燃机少得多，而且与活塞发动机不同，这些部件是旋转的，而不是往复的。不管它们是如何产生推进力的，无论是用螺旋桨驱动轴(涡轮螺旋桨)，还是用高速排气(涡轮喷气发动机)为飞机提供动力，还是运行内部风扇(涡轮风扇)，它们都有相似的设计。

All have a core that consists of a compressor—which does just as the name implies—plus a burner, which ignites aforementioned highly compressed and very hot air, and the turbine, which is the point of the first two parts. In the turboprop world, the hot exhaust gas that exits at the main turbine passes through an additional turbine before entering a nozzle. Most of the energy generated by this exhaust at the nozzle is then utilized to turn the secondary turbine. The secondary turbine is connected to a driveshaft and gearbox, which is then directly connected to a propeller, turboprop, or a turbofan.

它们都有一个核心，由一个压气机组成，顾名思义，加上一个燃烧器，它点燃前面提到的高度压缩和非常热的空气，还有涡轮，这是前两个部分的重点。在涡轮螺旋桨发动机的世界里，从主涡轮排出的热废气在进入喷嘴之前会经过另一个涡轮。喷口处废气产生的大部分能量被用来转动次级涡轮。次级涡轮连接到传动轴和齿轮箱，然后直接连接到螺旋桨、涡轮螺旋桨或涡轮风扇。

READ MORE: A 200-hp Turboprop for Homebuilts

阅读更多：一款适用于自建飞机的200马力涡轮螺旋桨发动机

Another benefit of turbine engines is the fuel that feeds their appetites (jet-A) is more readily available worldwide and typically at a lesser cost than its counterpart, avgas, which is short for “aviation gasoline” used in the piston world. In fact, turbine engines are like Mikey from the old Life Cereal TV commercials—they pretty much will consume anything within reason to satisfy their fueling hunger. With that in mind, in addition to jet-A, it’s expected that many of the microturbine engines will also be happy with other forms of kerosene, including over-the-road pump diesel fuel, especially in emergency situations. Manufacturers’ additional testing of these microturbines will ultimately determine what type of alternative fuels, if any, can be used on a permanent basis.

涡轮发动机的另一个好处是，满足它们胃口的燃料(jet-A)在世界范围内更容易获得，而且通常比其对应的avgas(活塞世界中使用的“航空汽油”的缩写)成本更低。事实上，涡轮发动机就像老生活麦片电视广告中的米奇一样——它们几乎会在合理的范围内消耗任何东西来满足它们的饥饿。考虑到这一点，除了jet-A，预计许多微型涡轮发动机也会很乐意使用其他形式的煤油，包括公路泵柴油，特别是在紧急情况下。制造商对这些微型涡轮机的额外测试将最终决定哪种替代燃料(如果有的话)可以永久使用。

TurbAero

涡轮发动机

Australian company TurbAero is developing a small, lightweight 200-horsepower engine, which will initially target those experimental aircraft that utilize conventional opposed-piston engines, usually the Lycoming IO-320 or IO-360 varieties (think Van’s Aircraft RVs and the like). TurbAero’s design utilizes a process called “recuperative technology,” taking the air that normally would enter the combustion chamber—in this case at 200 degrees Celsius—and, utilizing a heat exchanger, preheats the air by extracting waste heat from the exhaust gasses—and then uses that to preheat the compressed air, thereby reducing the amount of raw fuel required.

澳大利亚TurbAero公司正在开发一种200马力的小型轻型发动机，最初将用于那些使用传统对置活塞发动机的实验飞机，通常是莱康明IO-320或IO-360品种(想想Van 's aircraft rv等)。TurbAero的设计采用了一种被称为“回热技术”的过程，将通常进入燃烧室的空气——在这种情况下是在200摄氏度——利用热交换器，通过从废气中提取废热来预热空气，然后用它来预热压缩空气，从而减少所需的原燃料量。

This preheating, or recuperative technology, translates to an engine that can run more efficiently, burn less fuel, and operate with a good balance between performance, size, weight, and cost. A good balancing act, indeed. And, lest you think this is some newfangled technology, it’s actually a proven process that has been utilized on land-based vehicles, such as the M1 Abrams series tanks on the battlefield, with TurbAero resizing the recuperator, right-sizing it for the TA200TP 200-horsepower microturbine with the intent on bringing it to market sometime in 2025.

这种预热或回收技术转化为发动机可以更有效地运行，燃烧更少的燃料，并在性能，尺寸，重量和成本之间取得良好的平衡。这的确是一种很好的平衡。而且，为了避免你认为这是一些新奇的技术，它实际上是一个已经在陆基车辆上使用的经过验证的过程，例如战场上的M1艾布拉姆斯系列坦克，TurbAero调整了调温器的大小，为TA200TP 200马力微型涡轮机调整了大小，意图在2025年的某个时候将其推向市场。

TurbAero mini turbine [Courtesy TurbAero]How did TurbAero get into the microturbine game? As is often the case, the company came about by pure happenstance when its CEO, David Limmer, was looking for a turboprop engine for his own personal experimental aircraft in 2008. Not able to find one, the next best solution was to build one of his own, completing it in 2015. It was during this time Limmer recognized the potential for a range of small turboprop engines for aviation applications, specifically the experimental/builder’s market. Three years later, with funding in place and partnering with his brother, Andrew, TurbAero was formed. After attending numerous aviation symposiums worldwide and talking with various kit airplane manufacturers and many hobbyists, TurbAero settled on development of the 200-horsepower TA200TP engine.

TurbAero微型涡轮机[Courtesy TurbAero] TurbAero是如何进入微型涡轮机领域的？2008年，该公司的首席执行官大卫•利默(David Limmer)在为自己的私人实验飞机寻找涡轮螺旋桨发动机时，与往常一样，该公司的诞生纯属偶然。由于找不到一个，次佳的解决方案是自己建造一个，并于2015年完成。正是在这段时间里，Limmer认识到小型涡轮螺旋桨发动机在航空领域的应用潜力，特别是在实验/制造市场。三年后，在资金到位并与他的兄弟安德鲁(Andrew)合作后，TurbAero成立了。在参加了世界各地的许多航空研讨会并与各种飞机制造商和许多爱好者交谈后，TurbAero决定开发200马力的TA200TP发动机。

With additional refinements going into the fifth year of development, the company is poised to transition to the next phase, planned for the first quarter of 2024 and culminating in putting the engine through its paces on the test stand. Refinement will follow based on the results of the testing.

随着进一步的改进，进入开发的第五年，该公司准备过渡到下一阶段，计划于2024年第一季度进行，最终将发动机放在试验台上进行测试。将根据测试结果进行改进。

One of the current design refinements is optimizing the engine for operation and efficiency at lower altitudes. Like all turbines, these engines are most at home at the higher flight levels. However, TurbAero realizes that to be successful in the experimental market, it’s critical to provide a reasonable level of efficiency at the 10,000 to 12,000-foot range instead of the rarified air in the flight levels at which turbines are generally accustomed to operating. Considering the lower per-gallon price of jet fuel, along with the typically lower cost of maintenance compared to a reciprocating piston engine, and given the potential for higher reliability, the overall cost and benefit to operating the microturbine should likely fall within a range that most aviators in the experimental world would find justifiable, even with a planned price to market at $85,000. With the ultimate goal of bringing these microturbines to the certified market—in all likelihood, probably not for another five to 10 years—the question of overhaul recommendations comes to mind.

目前的设计改进之一是优化发动机在低海拔地区的运行和效率。像所有的涡轮机一样，这些发动机在更高的飞行水平上最适合。然而，TurbAero意识到，要想在实验市场上取得成功，在10,000到12,000英尺的范围内提供合理的效率水平是至关重要的，而不是在涡轮通常习惯于运行的飞行水平的稀薄空气中。考虑到每加仑喷气燃料的价格较低，与往复式活塞发动机相比，维护成本通常较低，并且考虑到更高可靠性的潜力，操作微型涡轮机的总体成本和收益可能会落在大多数飞行员在实验世界中认为合理的范围内，即使计划价格为85,000美元。考虑到将这些微型涡轮机推向认证市场的最终目标——很有可能，可能不会再过5到10年——检修建议的问题浮现在脑海中。

Most microturbine manufacturers are looking at TBOs of other certified turbines and seeking to replicate those in the marketplace, with the 3,000-hour TBO as the benchmark for future certification. In the meantime, since these turbines are designed for the experimental market, TBO is not a requirement now, although it’s likely these engine makers will look at safety and provide recommendations of their own long before their microturbine is spooling up in the certified world.

大多数微型涡轮机制造商都在关注其他认证涡轮机的TBO，并寻求在市场上复制这些涡轮机，以3000小时的TBO作为未来认证的基准。与此同时，由于这些涡轮机是为实验市场设计的，TBO现在不是一个要求，尽管这些发动机制造商很可能会考虑安全性，并在他们的微型涡轮机进入认证世界之前很久就提出自己的建议。

READ MORE: TurbAero Small Turboprop at EAA AirVenture Oshkosh

阅读更多：TurbAero小型涡轮螺旋桨飞机在EAA AirVenture Oshkosh展会亮相

In that regard, TurbAero is integrating a data acquisition function into the FADEC (full authority digital engine control) on their TA200TP engine. This purportedly will allow users of this engine to benefit from a health and usage monitoring system, designed to identify potential failure points before the failure occurs. It’s a grand prospect that could save maintenance costs at the very least and bent airframes at the very worst if it comes to fruition.

在这方面，TurbAero正在将数据采集功能集成到TA200TP发动机的FADEC(全权限数字发动机控制)中。据称，这将使该引擎的用户受益于健康和使用监测系统，该系统旨在在故障发生之前识别潜在的故障点。这是一个宏伟的前景，如果它成为现实，至少可以节省维护成本，最坏的情况下可以弯曲机身。

PBS Aerospace

PBS航空航天

Another turbine engine manufacturer, PBS Aerospace, brings its experience manufacturing propulsion systems for the defense sector, with expertise in tactical UAVs, target drones, and missiles, and enters the general aviation experimental market with a small, 43-pound micro turbojet engine that’s used in some SubSonex jets, as well as the BD-5J jet.

另一家涡轮发动机制造商PBS Aerospace将其为国防部门制造推进系统的经验，以及在战术无人机、靶机和导弹方面的专业知识带入通用航空实验市场，并将一种43磅的小型微型涡轮喷气发动机用于一些SubSonex喷气式飞机和BD-5J喷气式飞机。

According to vice president of customer support Frank Jones, the flexibility of the company’s TJ100 turbine engine will allow builders to utilize various versions of it, with some having a fuel-oil mix that will allow straight-up rocket-style launching without skipping a beat.

根据客户支持副总裁弗兰克·琼斯的说法，该公司的TJ100涡轮发动机的灵活性将允许制造商使用各种版本，其中一些具有燃油混合物，可以直接像火箭一样发射，而不会跳过一个节拍。

While PBS suggests a 300-hour time between hot sections at the moment, as additional experience and time gets put into these engines, the manufacturer may increase its suggested time between hot sections. Again, in the experimental world, these are simply suggestions, albeit strong ones. However, because there are so few hours being put on these microturbines, manufacturers like PBS are being ultraconservative in recommendations for overhauling/hot sectioning their turbines.

PBS建议目前热段间隔时间为300小时，随着更多的经验和时间投入到这些发动机中，制造商可能会增加热段间隔时间。同样，在实验世界中，这些只是建议，尽管是强有力的建议。然而，由于这些微型涡轮机的使用时间太少，像PBS这样的制造商在建议对涡轮机进行大修/热切割方面都非常保守。

At this time, PBS turbines in need of maintenance or hot sections require the engine to be returned to the company’s facility in the Czech Republic. However, as of this writing, since none of PBS’ TJ100 engines in the field have accumulated operational hours approaching the 300-hour mark, no overhauls have yet been necessary. Jones says the firm hopes to have facilities in the U.S. available for overhaul purposes when the time comes. In the meantime, as mentioned, other manufacturers are anticipating reaching similar recommended TBOs as their big brother counterparts, meaning 3,000-plus hours before the requisite hot section and overhaul. Pricing of the PBS TJ100 is in the $80,000 range, depending on accessories and other options.

此时，需要维护或热段的PBS涡轮机需要将发动机送回公司在捷克共和国的设施。然而，在撰写本文时，由于PBS公司的TJ100发动机在现场的累计工作时间都没有达到300小时大关，因此还没有必要进行大修。琼斯说，该公司希望在时机成熟时，在美国拥有可用于大修目的的设施。与此同时，如前所述，其他制造商期望达到与他们的老大哥同行类似的推荐TBO，这意味着在必要的热段和大修之前3000多个小时。PBS TJ100的定价在80,000美元范围内，取决于配件和其他选项。

Heron Engines

苍鹭发动机

For those who don’t want to wait for the development of those microturbines still in the testing stage and earlier, there’s one manufacturer—Crete, Greece-based Heron Engines—with a 130-horsepower version ready for preorders. Although you may be sacrificing some available horsepower compared to others that are developing 200 hp versions, the Heron microturbines, weighing in at a svelte 82 pounds, with gearbox and developed after decades of work designing and building UAVs from founding member Alex Vrontoulakis’ father, are available for preorder today. Vrontoulakis is now partnered with Alex Fatseas and since 2018 they have been committed to bringing their microturbines to market, with the company promising to make them affordable (low $40,000s), easy to maintain, with projected overhaul costs in the $7,000 range.

对于那些不想等待还在测试阶段或更早阶段的微型涡轮机开发的人来说，有一家制造商——位于希腊克里特岛的Heron发动机公司——已经准备好预订130马力的版本。虽然你可能会牺牲一些可用的马力相比，其他人正在开发200马力的版本，Heron微型涡轮机，重量为82磅，齿轮箱和开发经过数十年的工作设计和建造无人机的创始成员亚历克斯Vrontoulakis的父亲，今天可以预订。Vrontoulakis现在与Alex Fatseas合作，自2018年以来，他们一直致力于将微型涡轮机推向市场，该公司承诺使其价格合理(40,000美元以下)，易于维护，预计大修成本在7,000美元左右。

Solar Turbines

太阳能涡轮机

You wouldn’t normally think a turbine engine used primarily as a helicopter auxiliary power unit (APU) or ground power generator would be a good fit as a primary source of propulsion. But in the case of the Solar T62, the manufacturer says, you would be wrong. This compact engine continues to see some use in the experimental helicopter world, where it can be found in kits made by Rotor X Aircraft Manufacturing (formerly RotorWay International) and Mosquito Aviation (the single-seat Mosquito homebuilt helicopter). However, you might need to look hard for one of these as they are few and far between, and mostly found on auction sites such as eBay. When you can find one on the market for sale, you can expect to shell out about $15,000 for the T62 turbine—and of course, we’re talking used.

你通常不会认为涡轮发动机主要用作直升机辅助动力装置(APU)或地面发电机将是一个很好的适合作为主要的推进源。但在太阳能T62的情况下，制造商说，你可能错了。这种紧凑型发动机继续在实验直升机世界中使用，在那里它可以在转子X飞机制造(以前的RotorWay国际)和蚊子航空(单座蚊子自制直升机)制造的套件中找到。然而，你可能需要努力寻找其中一个，因为它们很少，而且大多在eBay等拍卖网站上找到。当你能在市场上找到一个出售时，你可以期待为T62涡轮机支付大约15,000美元，当然，我们说的是二手的。

Other Turbine Benefits

涡轮机的其他优点

Because 100LL is becoming more scarce by the day internationally, industry experts predict per-gallon costs are going to continue their upward spiral. Having an engine that burns jet-A will assure more savings in the future, which will be an added benefit overall.

由于100LL汽油在国际上日益稀缺，业内专家预测每加仑汽油的成本将继续呈螺旋式上升趋势。拥有一个燃烧jet-A的引擎将确保在未来节省更多，这将是一个额外的好处。

So, what will it take to enter the rarified air of the turbine world? Like many things in aviation, time and money. Time, since we’re in the infancy stage of microturbine development. And, of course, money, since the price of admission for experimental microturbines will fall somewhere within the $40,000 to $85,000 range and potentially go higher by the time they come to market.

那么，怎样才能进入空气稀薄的涡轮世界呢?就像航空业的很多东西一样，时间和金钱。时间，因为我们正处于微型涡轮机发展的初级阶段。当然，还有钱，因为实验性微型涡轮机的准入价格将在4万美元到8.5万美元之间，而且在它们进入市场时可能会更高。

Cessna Turbo Stationair [Courtesy Textron Aviation]With the advent of these microturbine engines, it’s quite possible we’re at the inception of a new phase in propulsion for experimental aircraft and beyond. While there are numerous obstacles to overcome, not the least of which is the cost of acquisition, obtaining efficient operation at lower altitudes and proving the microturbine design is sustainable in our ever-demanding world of aviation, there’s cautious optimism that in the not-so-distant future, we will all be hearing the unmistakable sweet sounds of turbines spooling up much more frequently at airports around the world.

随着这些微型涡轮发动机的出现，我们很可能正处于实验飞机推进新阶段的开端。虽然还有许多障碍需要克服，其中最重要的是采购成本，在低空获得高效运行，并证明微型涡轮机设计在我们不断要求的航空世界中是可持续的，但谨慎乐观地认为，在不久的将来，我们都将听到涡轮机在世界各地的机场更频繁地发出甜美的声音。

Editor’s note: This story originally appeared in the July 2023 issue of Plane & Pilot magazine.

编者按：这个故事最初出现在2023年7月的《飞机与飞行员》杂志上。