Recently I had an exchange with Australian Flying magazine editor, Steve Hitchen. He asked some great questions and after giving my responses I realized some of his question were common ones I hear being discussed. So why not share our give-and-take? Steve’s questions are in blue.
I’d like to talk about power. With LSA restricted to 120 KIAS, it seems unlikely we’ll get much engine development to increase power unless regulations change to either allow an increase in speed or gross weight.
LSA are getting more power, to wit, Rotax’s new 915iS with 135-horsepower and the Continental Titan line with 180 horsepower. I do not think this is the end of the horsepower boosts …plus LSA speed and/or weight changes could conceivably follow in the USA but are currently not limitations in other countries that accept the ASTM standards as a basis for approval or certification.
What would be the point of more powerful engines on LSA?
Well, beside pilots’ interest in having more power, aircraft operating at higher elevations and seaplane or floatplanes benefit from more power even when they cannot fly faster.
There’s already a lot of technology in LSA thanks to the need to save weight, which has me wondering where the sector is going. Can you provide me with some thoughts?
Well, that topic could take us down quite a lengthy path. Let me offer a somewhat shorter reply.
You are right about many tech developments — and on that I point you to an article published recently in General Aviation News’ “The Pulse of Aviation.” Two thoughts: (1) I believe the LSA sector has reached an interesting level of maturity. The pace of major innovations may have slowed but the most important developments are now common on most LSA (and light kits). This situation is not so different than smartphones that totally upended mobile a decade ago with the introduction of the iPhone. In a similar time period, that industry has also matured and development has lost its torrid pace. (2) The funny thing about innovation is you often don’t know how or when it might emerge. Electric propulsion is one possibility and then we are seeing the first glimmer of a new class of aircraft with a collection of spinning blades or rotating wings. Who can guess where precisely that is headed? Whatever the coming changes, they will work first on lighter aircraft. My article referenced above tries to speculate a bit.
By the way, the use of technology seeks not only to save weight. New methods are used because they can, that is, developers don’t need to jump through the regulatory hoops as demanded in Part 23. LSA developers can quickly implement new ideas and materials.
Boeing’s Aurora is one of a flock of new developments aimed at the air taxi trade but it could result in a sport model.
Composite versus metal. Is there something else? What type of composites are in common use and what types are under development? What drives composite development? Does metal still have a future in LSA? Is mix-and-match of both the way to go?
One definition of composite is “made of various materials.” In the past “composite” implied fiberglass. LSA already rely on fiberglass, aluminum, and steel but add high-tech materials such as Kevlar, carbon fiber, and titanium. Today, the most advanced designs have significantly carbon fiber airframes, partly for weight but also strength as well as aerodynamic efficiency and design beauty.
However, metal seems here to stay, being highly established and proven. Its advantages in easy repair, easier-to-determine fatigue, and a widespread familiarity of working the material — along with low weight — will keep aluminum in play.
What are the major construction methods? Is there room for the construction method to contribute to the aircraft performance in terms of weight saving? Aircraft like the Ekolot Topaz have fuselages formed in two halves then adhered together like a Revell P-51 model. Is this the way of the future? Is there room for mass production?
That’s one beauty of fiberglass and carbon. You can have beautiful shapes and strength with weigh savings. Assembly ease is a factor, too. Those materials will surely persist for those reasons and for future production efficiencies. However, since nearly all airplanes are low-production — essentially hand-built with modest use of robotics, even at the Boeing or Airbus level — prospects for genuine mass production seem distant.
Avionics development has seen technology cascade down from GA, but there is some that has been designed from scratch for the LSA sector, such as AoA Indicators. Which way will the technology flow in the future? Is EFIS going to become standard for LSAs or do the traditional clocks still have a place? Have we reached a pinnacle in LSA simply because the sector can operate without technology such as HUDs?
Actually, I don’t believe it is accurate to say instrument technology cascaded down from GA. Instead, I think the best tech has cascaded UP, if you will, from lesser-regulated machines. Many airline pilots look at a modern LSA and say, “Wow, this is as good or better instrumentation than what I have in my airline cockpit!” For example, synthetic vision has been around for years already in LSA. Today, EFIS is pretty much standard in all LSA and, to some extent, that is spreading to Type Certified aircraft in the form of iPads that can now show full ADAHARS info plus traffic and weather. Since these can be handheld or yoke mounted, they need no FAA/CAA approvals. HUD is also coming but at more affordable prices. Who can predict what future tech is on the way. AoA has been around for years as well, and commonly the cost to add an AoA system is $200± per aircraft (as the digital screens can easily adapt to minor hardware additions); this is a small fraction of the cost on TC’d aircraft. One thing I feel sure of — the newest tech will appear in the least regulated aircraft first. As one more example, the very first use I know of for GPS, anywhere in aviation, was on hang gliders of all places.
Weight-saving is always an issue for manufacturers. In Australia a land-based LSA can lift no more than 600 kg (1,320 pounds), so what can manufacturers do to increase their useful load? Are we reaching a dangerous situation where the aircraft are getting too light or are too heavy to include some desirable safety features, such as parachutes?
Perhaps we are pushing some boundaries if new ideas and materials are not forthcoming. However, they are forthcoming. I’m not too worried about it. For example, crush zone technology in cars did not add weight — in fact removed it compared to other methods — and this greatly added to safety.
Are regulations stifling LSAs? Should LSAs be able to fly at up to 750 kg MTOW (1,650 pounds gross) to give manufacturers more design freedom? Is there anything that has to change to enable more technology to be used in LSA, and if so, what is it?
As a rule, I’d rather see less regulation to encourage more innovation. Even FAA appears to agree, based on their Part 23 rewrite recently released. Many tend to think regulation makes for safer aircraft, but (1) that is matter of diminishing return — how much safety is gained from more regulation? — and, (2) regulation is not the only way safety has advanced. Insurance companies have demanded improvements that FAA didn’t consider. Media people help improve designs by their critiques. Other industries contribute tech that improves safety, if regulations don’t prevent it. Consumers are another bulwark against dumb ideas and for more creative and cost-efficient safety solutions. Finally, competition stimulates improvements, the best of which quickly flash around an industry. Look how similar airliners or smartphones appear. The most successful ideas tend to be used by everyone in time.
There’s a lot there, but there’s also a lot to think about. Until the rewrite of FAR23, the LSA sector led general aviation in technology, especially in the use of composites. The new FAR23 is sort of like catch-up regulation for GA, but where does the technology leader, LSA, go to from here?
You are right that LSA is leading the innovation charge in many ways. Where can the industry go from here? We (LAMA) have spoken to FAA a lot in the last three years as we seek new opportunities within the present regulatory framework. It is perfectly clear that LSA were a significant reason why FAA went ahead with the Part 23 rewrite and use of industry consensus standards. To answer the future question, I again refer you to this recent article.
The freshest new tech in aviation may come from outside aviation but I would never discount the passionate, imaginative, and motivated designers and developers operating in light aviation today.
Mahmood Hussain says
Why you don’t change the propeller? Instead of using one from 1903!! go and see this Website: http://www.horizonwaves.com
Dan Johnson says
Hello Mahmood: We will post your comment but observe that props on Light-Sport Aircraft must meet ASTM standards. Homebuilders can try any prop they like.
Shalom Confessor says
Great post, Dan. Our team agreed 100% of your ponderations.
The FAA ought to consider adoption of EASA conditions for LSA. The primary EASA condition for LSA is a stall speed of 35 Knots and there is no maximum speed.
Most accidents occur during take-off and landing and the maximum stall speed of 35 Knots goes a long way to reducing the force of impact and survivability of such an accident.
There is very little difference in the risk of an accident occuring, or its outcome, at a cruise speed of 120 KIAS or at 170 KIAS (200 KTAS at FL100) which some LSAs in Europe are now able to achieve with the Rotax 915iS which has now been certified with a maximum power output of 141 horsepower and maximum continuous power output of 135 horsepower up to FL150.
Constant speed propellers improve take off performance, which enhances safety, and improves efficiency reducing fuel consumption and engine wear and tear. Modern digitally controlled constant speed propellors are largely automated and very simple to operate. They should not be prohibited. They are not prohibited by EASA and there have been few, if any LSA accidents, caused by constant speed propellers.
Retractable gear improves efficiency, improves cruise performance and reduces fuel consumption. Retractable gear does not require complex hydraulic systems. Landing with the gear up at 35 Knots does little damage to composite aircraft. Almost all modern gliders have mechanical retractable gear. Retractable gear should not be prohibited. They are not prohibited by EASA and there have been been few, if any, serious LSA accidents caused by retractable gear failures.
Both FAA and EASA should consider allowing the installation of turbine engines because small turbine engines are mechanically simpler, simpler to operate and more reliable than piston engines. This would encourage the development of small, reliable and affordable aircraft turbine power plants ie in the Rotax range of power output, see for example, http://www.StuttgartEngineering.com
Finally, a small increase in MTOW to say 750 kg would permit the installation of enhanced safety features such as larger and stronger cockpits together with impact absorption materials which could make 35 Knot impacts a ‘walk away’ outcome just as a 40 mph collision in a road traffic accident today.