The Really Big Risk for Composite Airplanes

Imagine that you are an established airplane manufacturer planning your next all-new airplane design. The project will cost many millions if you are going to build a light airplane, to many hundreds of millions, or even billions if it’s a jet. The big question is what to do about using composite materials to build most or all of the new design?

Looking at the history of certified composite airplanes is scary. Beech spent about $1 billion to develop and produce about 50 Starships. The airplane missed every weight and performance goal and the market for the exotic looking turboprop just didn’t exist.

Adam Aircraft is another worrisome example of composites gone wrong. The centerline thrust piston twin A500 also came out heavier than expected and was more costly to build. It was eventually certified but its payload and performance restrictions dried up what had been a promising market.

The situation at Boeing with the 787 being years behind schedule and who knows how many hundreds of millions over budget is the stuff of nightmares for executives who must decide what type of airplane to build next. The composite construction of the 787 is definitely not the only issue in development, but it is a major suspect in the delays to develop the first large jet made mostly from composites.

Beech has had better luck with the Beechjet and Hawker 4000 that use composite construction for the fuselage and aluminum for the wings and most other components. But even though those airplanes are in service, both jets took much longer and cost more to develop than expected.

Adam Aircraft's A500 piston push/pull twin featuring TIO-540 engines. The company also developed the A700 turbojet before financial troubles doomed the company in 2009.

Cirrus and Diamond have both succeeded in building airplanes almost entirely from composite materials, but their situation is different. Neither company had long-established procedures to design and build metal airframes, so they were not risking a change away from a successful past. For them composite construction was at the core, not a new risk. But still, the Cirrus and Diamond airplanes have not demonstrated significant, if any, weight advantage compared to similar-sized metal airframes. The composite airframes are very smooth, and have shapes that would be almost impossible to create in metal, but the weight savings that can be achieved in the laboratory haven’t survived the certification and manufacturing process.

Even kit makers have had fits and starts with composite construction. Thirty years ago it looked like aluminum kit planes were finished as we all believed building with fiberglass was quicker, easier, and lighter, and produced airplanes of superior performance. Somebody forgot to tell Dick VanGrunsven. As it turned out, the all-metal Vans RV series of kits has become more popular and successful than any family of kit planes in history with more than 7,000 kits completed and flying.

So if you’re the guy at big airplane company X who has to pull the trigger on a new composite or mostly composite design, the history of composite airplanes tells you to run the other way. But doing that is where the biggest risk resides.

At some point the promise of composite construction will become reality. Even if the potential weight savings are never fully realized, the reduction in parts count and labor during assembly will become real. Someday the idea of riveting together hundreds or even thousands of metal parts to form an airframe will seem as quaint as wrapping fabric over a maze of wood and metal tubes.

Beech spent $300 million in development costs and sales were slow. A total of 53 were built and the line was discontinued in 1995, 12 years after the first flight.

We have seen the disaster of the companies that got it wrong on composites. But another potential disaster looms for the company that gets it wrong and stays with metal too long. A successful new airplane design needs to endure in production for many years, even many decades. The perfect example is the Boeing 737 that continues to be one of the most popular airplanes in the world, even though the original design is nearing its 45th birthday. Boeing got it right in the 1960s and the 737 is helping to pay the bills for the issues the 787 has encountered in the new century.

That’s why every established airplane manufacturer is spending a bundle to study composite design and manufacturing. Even as metal airplanes roll off the assembly line, the bosses at airframe manufacturers know each new design must contain a greater extent of composite components to be competitive over the long term.

Learjet has pulled the trigger with its new model 85 that is pretty far along in development and will be made almost entirely of carbon fiber. Did Learjet get it right? That’s what worries other airplane manufacturing executives. If Learjet is correct – and the Boeing 787 eventually delivers on its promises – the other companies waited too long. But maybe Boeing and Learjet made the wrong call and like Beech went too much composite too soon. We won’t know who is correct for several years to come.

I bet the leaders of the big airplane companies see carbon fiber in their nightmares more than their dreams because one day somebody will get it right, and the others will be playing catch-up.

This entry was posted in Aircraft, Industry & Government, Technology. Bookmark the permalink.

31 Responses to The Really Big Risk for Composite Airplanes

  1. Author says:

    From what I heard, problems with 787 are only indirectly related to composites, but rather are managerial in the nature. It hard to expect much from a company that moved HQ to Chicago. For example, consider the saga of the tail that was offset to Italians and came back with poor workmanship. Who knew, right?

  2. Marco L says:

    Being in the engineering field, I know there are many reasons why projects get delayed. The success or failure of a particular model or line is riddled with even more reasons. While I think your final conclusions are right on the money, I think more study is needed in how composite materials and/or the ability to efficiently manufacture those parts played a role in each of the delays in the 787 program. Project management, subcontractors, aggressive scheduling and component integration (unrelated to composites) are potentially major sources for big delays that may or may not be related to composites. It would be interesting to compare the delays in the 787 program to the F-35 program. We may gain better insight into the role composite materials or, more generally, “exotic” materials, may play in the success of a particular program.

    Love the blog Mac. Your column was what I missed most after the changes at Flying. It feels good to get my “fix” again.

    Marco

  3. Dick Kaiser says:

    Marco has it right. I thoroughly miss your input at Flying and am glad to catch up via your blog and EAA. Glad you are where you can sail and receive “as filed” clearances. Many thanks, Dick

  4. Marco L says:

    Dick, you must be a Northeast (or Class Bravo) flyer as well to treasure those “as filed” clearances. I know a guy who knew a guy once that got an “as filed” clearance out of Long Island and never got re-routed!

    But I think he’s BSing me…

    • Dick Kaiser says:

      Hi Marco! No, mostly filed out of Reno , Nevada, or Gunnison, Colorado, although I’ve received the “cleared as” out of Bar Harbor and Hartford. Stay well, Dick

  5. Robert J. Mudd says:

    I have built several composite aircraft and operate a composite aircraft repair business. I feel qualified in making some comments on this article. Weight savings of composites over metal will not be realized with hand layup methods which is the process most of the GA manufacturers use. Using resin transfer molding helps but it is just that a help. The big bucks manufactures can afford pre pregs, and autoclaves and can get more of the performance that composites promise. Comparing what GA manufacturers do with what Boeing et.all do is not valid.

    Having worked for several composite aircraft manufacturers and toured some others I find that some of the weight gain is from poor manufacturing practices. Composite aircraft can not be built the same way that metal aircraft are built. Also certification requirements for composites are newer and more stringent, weight is gained there too.

    As to the quickness of building a metal homebuilt verses a composite one; the real difference is in how organized and dedicated the builder is. I know some one who is building a John Monett design, a clever and simple design, he is in his 3 year. I think I could build any of the current composite design in that time or less. As with any building material, hanging out with an experienced builder or builders group is very helpful.

    Composites offer the freedom to have a very aerodynamically clean design, the modern airfoils are mostly only doable in composites. On the market now is a composite two seat, side by side aircraft with the Rotax 100 hp engine that cruises 147kts. It could not be built from metal and have that performance.

    Companies with decades long composite manufacturing experience are making very efficient airframes and easily meeting weight goals. Sadly most of them are in Europe. For the side of the aviation spectrum that we EAAers operate in composites offer a wide variety of performance opportunities.

    Robert

    • Barret says:

      Robert,

      What part of the country are you in and how did you get started in composites? I am really interested in building my own aircraft and learned composite lay-up on the formula SAE team at my college. I’m not an engineer, but am a metal fabricator, ironically.

      -McCaffrey

    • I can easily disagree with the common assumption that you can only create smooth aerodynamically complex designs using composites. The wing of my 1966 Meyers 200D is much more complex than even the latest production and experimental GA composite aircraft built today. The Meyers 200 wing tapers from thick to thin in both cord and thickness and it’s got a large amount of twist in the wing so that the inner portion of the wing stalls first and even in the stall I have full aileron authority because of this. Part of the wing is steel covered in non-structural aluminum while the rest of the wing is standard monocoque aluminum construction. It’s so smooth that many people think that my wing is in fact composite when they first see it (no visible rivets, etc….). And, all this was designed using slide rulers. Can you create this type of complexity in a composite wing? Absolutely. But, so far, nobody has.

      • Mac says:

        Building exotic wings from metal can be done, and as you point out, has been done many years ago. But the shapes that would be difficult to create in metal are the tiny tailcones on some Diamond airplanes, and on several LSA. Fairings on many airplanes would be more difficult in aluminum than in composite. However, the Meyers 200 remains an interesting example of an airplane with a small wing area that still managed to meet the 61 knot maximum stall speed requirement for certification.
        Mac Mc

  6. R.J. Reilly says:

    Nobody has mentioned structural integrity and UV considerations. An engineering acquaintance, that many would recognize, has produced a few high performance kit airplanes and a successful commuter turbo prop. When I asked how his metal fabricated kits would compete in a composite world he responded, thumping a wing skin, “I know exactly what this stuff’s properties will be in 30 years.”

    I have observed several sailplanes, living a pampered existence mostly disassembled and stored in their trailers, that developed delamination problems after only a few years. Working airplanes may spend more of their time exposed to the elements especially after working their way down to the second and third owners. Is this sort of problem limited to hand layup manufacture? Perhaps someone out there with experience in composite structures might address this general area.

    RJR

    • Mac says:

      The earliest fiberglass boats are nearing their 50th birthday so the armada of millions of composite boats can tell us something about how the material ages. And there have been some surprises in boats. For one fiberglass and gelcoat are not waterproof as originally thought. Also, what appeared to be a good bond originally can delaminate later. Water intrusion is a big problem and cause of delamination, but other than cosmetic destruction of the gelcoat or paint, UV rays do not seem to have been a big problem for boats.
      Boats are not airplanes. Thank goodness airplanes don’t have to live with a portion of their airframe submerged in water, particularly salt water. Even when stored outdoors it would seem that a fiberglass airplane lives an easier life than a boat floating in its slip.
      The one issue that appears to be common to composite boats and airplanes is corrosion. Both boats and airplanes must use at least some metal parts and where there is metal, there will be corrosion.
      I learned to fly on the east side of Cleveland many years ago and the American Aviation factory was on Cuyahoga County Airport there. All of the old timers, and some of us then young timers, scoffed at the Yankee and Traveler with their bonded metal in place of fasteners, and the honeycomb material to stiffen the fuselage. Many thought the Yankee airfame wouldn’t last as long as the engine. Well, there have been some minor problems with the American Aviation airplanes, but nearly 40 years later most of them are still around.
      Mac Mc

      • Richard Bradberry says:

        Mr. McLellan: I am not qualified to comment on composites but would like to ask If you worked for Beech Aircraft circa 1968-1970. Also, did you have a friend named Terry McNay? Thanks for your time.

        R.F. Bradberry

  7. Ray Tolhurst says:

    Composites will always be at a weight disadvantage compared to aluminum and steel because the known strain to failure of the metals allows a designer a safety factor of 1.5 whereas the composite designer knows the vaues of the fibers but not so much for the matrix that supports them. A 2.25 safety factor is used if tested at room temperature so you already have 50% more material than could do the job if everything was known. The trick with composite design is to only put the material where it is needed. This is not usually done due to the complexity of the layup schedule and the chance of mistakes being made in production.

    • Mac says:

      As you probably know, there are two static design loads an airfame, particularly the wing, must meet for certification. The basic requirement is the limit load for the category of certification, typically 3.8 g positive for a normal category airplane. At limit load the wing can’t break, of course, but it also cannot have any permenant creases nor can it take a “set” from its original shape when the load is removed. The second test load is called ultimate load and is 50 percent greater than limit load. At ultimate load the wing can crease, and crinkle and take a set from its original shape, but it just can’t break.
      Composite structures do not crease or crinkle the way metal can to relieve stress so the composite structure at ultimate load is going to return to its original shape after the load is removed. Ultimate load testing is a big challenge for metal structures, but an even greater test for a composite one.
      Mac Mc

  8. Thomas Ivines says:

    Well, Mac, you got it right for the really big airplane manufacturers, but for general aviation the composite airplane has become one of choice. The Cirrus is a good example of that and now we need to take a closer look at the Kestrel, too.

    The light sport arena is prominent in composite construction and there is much more to come in the near future. Pound for pound the composite airplane is stronger, sleeker, faster and more economic to operate. Why shouldn’t it be the preferred method of construction for all airplanes in the future, big and small?

    I do have one valid concern, though, and it is how composite airplanes will hold up to the elements. Metal stands up to UV rays far better than even carbon fiber, and we all know what happens to fiberglass when left outside. Time will tell but right now I believe composite airplanes are not to be left on the tarmac, but instead they should be hangared when not in use, especially if they are to match the basic 35-year-old fleet of GA, metal airplanes still flying today.

  9. Brad says:

    Way, way too simplistic and overly broad in your conclusions.

    First, you said the metal kitplanes were finished 30 years ago, until Dick Van Grunsven came along. Ummm….what metal kits even existed 30 years ago? Maybe a small, boutique level supplier of components like Mustang Aeronautics. Van’s success is in simplicity and repeatability in the production of high quality kits and parts, not because of a sudden rediscovering of metal by homebuilders. He’s a Henry Ford.

    The Starship was unsuccessful because of its configuration, not because of composites. Burt himself has quietly moved past canard designs. If they were even a fraction more efficient, Boeing and Airbus would have been all over them in a heartbeat. To blame composites on the failures to deliver on design promises is absurd. An example, the McDonnell Douglas MD-11, a METAL plane, was a big design failure, as it could not deliver on its performance promises to its airline customers. Configuration and engineering are everything, not carbon and glue vs. sheet metal and rivets.

    Boeing moving its headquarters to Chicago was a business move. Washington state has oppressive corporate taxes (although they might be looking to move again in light of Illinois’ recent tax increases), and Boeing is a massive, diverse company that has to make these business decisions to stay afloat. It goes way, way beyond a material choice in one aircraft in their Commercial Airplanes Group.

    I’m an RV-7 builder, so I’ve got no skin in the composites game. Still, I don’t feel convinced that you’ve put any credible arguments against the move to composites. Sure, the thinking that they’re a “wonder” material is as silly as “Burt can do anything”, but they do have real value in future design…..especially in fuel-efficient, low drag concepts.

    I would research your topics more carefully before having such a strong opinion about something you don’t know much about.

    • whit says:

      Brad, I happened upon this website after researching safety of commercial “composite built” aircraft. You appear to be an engineer. I know nothing about aircraft, flight or engineering but simply am curious of the safety of the new “commercial use” of composite built aircraft. From an engineers viewpoint, I’m curious to know if you feel these aircraft are safe for you and your family to travel on??

  10. Spinoneone says:

    Certification issues and weight have combined to end a lot of well intentioned projects over the past 10 or 15 years. However, they do keep on coming. See here for a 245Kt, tandem turboprop for about $3 million, unpressurized. http://www.flightglobal.com/articles/2011/02/01/352414/flight-test-grob-aircraft-g120tp-pocket-rocket.html

  11. John Innes says:

    I suspect the 100hp 147kt two-place composite is the Pipistrel Virus [Veer Us] Short Wing which is an example of innovative design in composite construction. It also has a 17:1 glide ratio. It won the overall CAFE prize in 2007 and 2008 plus category prizes for quietest cockpit and rate of climb.

    Designed and built in Slovenia, it is certified in the U.S. and Germany.

  12. Mike Lewis says:

    Mac got it exactly right, but I think many of the readers missed the point. It is not so much about what material or technique is best. It is more about the timing of a business decision. This is really no different than thousands of other evolutionary processes. It is no more about replacing aluminum with composits than it is about replacing pot metal castings with plastic moldings or mechanical indexers with servos or line shafts with electronic drives etc. The issue is at what stage of the evolution do you commit to the newer technology. The ones who commit too early fail, and the ones who commit too late fail. The ones who time it just right, capitalize on the incorrect choices of the others. They profit by observing and learning from the premature entries and they profit by having a head start in the market over those who wait too long. Guess who decides when the right time is? None other than the free market! The successful business guys are the ones who can read that free market.

  13. Pingback: The Really Big Risk for Composite Airplanes » Calgary Recreational & Ultralight Flying ClubCalgary Recreational & Ultralight Flying Club - Current Aviation News, Videos, Photos, Classifieds, Calendar, Podcasts, CRUFC Club Information, Pilot

  14. Bob Hartunian says:

    I worked in the commercial airframe composites business for 35 yrs and built many flying structures. The driver for composite applications was initially weight savings over aluminum because of inherent lower density of a graphite/epoxy composite laminate and a major potential for increased strength and stiffness for a given cross section. Both properties are favorable and result in improved aircraft performance. The learning curve to build parts reliably took years to accomplish and the engineering design data took more money and time to generate, much with government support. Airframers are now able to accurately design and build large structure with predictable results and can build with known manufacturing costs when the processes are controlled through the use of capital intensive equipment like autoclaves and fiber placement machines and non-destructive inspection machines to assure produced parts are airworthy. The producibilty problems happen when the design and manufacturing work is jobbed out/outsourced to suppliers who can’t perform and any cost savings evaporates as delivery slips.
    Carbon composites do function as reliably as aluminum and usually better from a fatigue and corrosion viewpoint. The basic limitation of composites is the lower damage tolerance from impact energy due to a lack of laminate plasticity. But this is understood and accepted within design parameters and the resulting structures are stronger and less suseptable to environmental effects than aluminum.
    There is a quality difference between what an airframer builds and what a home builder makes in the form of resin content/performance and laminate porosity and compaction. But the design stresses in a homebuilt are purposely reduced to accomodate the levels of achievable quality so the resulting product works safely and reliably.
    As for comments about UV suseptability, when you paint a composite, which keeps it protected from UV, there is no damage to the resin matrix and it will last just as long as aluminum with the primers and coatings required to keep it from turning into powder. Each material system has its unique building requirements and advantages/limitations; composites do provide lighter and stronger structures and will increase in use as the knowledge from airframers trickles down to homebuilders.

  15. Robert J. Mudd says:

    I got my start in composite , as did many other of my generation, by building a Rutan design. In my case a Vari-Eze. Burt’s basic education manual on moldless composite construction is still valid more 35 years after being written.

    From there I went on to building high performance sailplanes in Albuquerque, NM. Then schooling for Hamilton Standard composite props, and repairing gliders part time, plus reading everything I could find about composites. I then got a full time job helping to design and build a high performance composite glider for series production. That project took me to Lithuania from where I was able to visit all the European glider manufacturers and suppliers. I still maintain my contacts there. After that I worked for the largest GA composite aircraft a manufacturer both in the factory and as a service representative in the field. I now have my own repair shop in Moriarty, NM.

    As to the life limits on GA composite, simply put there are none. Several national aviation authorities have done extensive testing and the result is there is no life limit. All the European made composite gliders have inspection intervals, usually about 3,000 hrs. There are two seat glider in the fleet with over 9,000 hours with no serious structural problems. The first series built composite gliders were produced in the late 1950s. Several of them are still flying. In fact the long life of composite airframes is a slight problem because the structure does not wear out, there are a lot on the used market. This is good for private owners looking to buy a good older generation glider but stifles new products.

    As with any structure be it a bridge or an aircraft, regular preventative maintenance is important. As one poster noted, maintaining the surface paint or gelcoat is of paramount importance. Believe it or not gelcoat does not have to crack. Every time I have found deteriorating bond lines or laminates it turns out the owner or owners have not practiced proper care of their toy. Keeping a glider in a trailer is no more protection from corrosion than keeping your metal plane in a T hangar. Both aircraft take more TLC than that to stay in good condition.

    The beauty of composite is in being able to get complex or very organic shapes easily. Today’s mold making technology is amazing. A mold half for a prototype fuselage or for a limited production run can be made over night. If one section need modification that area can be cut out and another made over night. The same can be and is being done with wing molds.

    The Meyers 200 is a beautiful aircraft but if you were to take it apart you will find it has a very high parts count. I understand this was also true of the composite Learfan. It was apparently a composite airframe designed like a metal one. Modern composite airframes have a relatively low parts count. Properly designed bond lines do not fail in normal use. Of course the good thing about metal airframes is that you know where to look for cracks, at the thousands of holes drilled for rivets. If you take a typical rib attachment to a wing skin the entire flange will be bonded to the wing skin in a composite airframe. In a metal aircraft only the 1/8 or 3/32 dia. rivets keep the rib attached to the wing skin. In between them is nothing.

    As for aerodynamic complexity of a wing I’ll put the ASW-20 wing up against any other in GA.. The ailerons droop with the flaps for climbing to about 12 deg. Then as the flaps continue down to 55deg. for landing the ailerons reflex up to keep the wing tips from stalling. The flaps follow the ailerons for roll control at normal flap settings and the entire trailing edge, flap and aileron, reflexes up for high speed cruising. The wing is very simple and has only one structural rib and that is at the root. It is amazing to watch it work and even more amazing to fly.

    For every application there is an optimum material. Composites are being used in more and more applications. But metal will always be with us just as the original airframe material, wood, still is. Pick your material and start building.

    Robert

  16. Pingback: The Really Big Risk for Composite Airplanes | Aviation Blogs

  17. jdm says:

    As for efficiency and cost at the pumps, my 1981 Mooney 231 does 175 kts true at Fl180 on 10 GPH, thanks to GAMI jectors. As a glider pilot, where everything is fiberglass or carbon fiber, I can say that the Mooney certainly could be a lot aerodynamically cleaner with composite construction, but let’s be real – the inefficiencies of our airplanes has more to do with the ancient, fixed, mechanical systems in our Conti’s and Lyc’s than with what material the airframe is made of.

  18. J. McG says:

    In large part, the author’s opinion harkens to the days of calling the internal combustion engine an “explosion” engine for fear that the constant combustion occurring would cause the engine to become an uncontrolled bomb. If we were to discard any new material with the promise of composites because we fail a few times along the way, we’d condemn ourselves to horses and buggies and bicycles with HUGE front wheels. Never would I say we should drop all current methods because something new came along. I would however suggest we find the greatest benefit of all the options and attempt to use them in a way better than can be achieved by focusing only on one. A combination of materials, each used to their strengths, is the way to achieve aircraft proving to be better and better with each revision. It must also be understood that these improvements won’t suddenly produce a Ferrari at the cost of a Yaris. I think one of the most frustrating aspects of evolution is the slow, almost imperceptible, rate at which it occurs. Especially when compounded by so many frivolous claims about the next amazing breakthrough that is never actually realized.

  19. We are a group of volunteers and opening a brand new scheme in our community. Your site provided us with helpful info to work on. You have done a formidable task and our whole community will probably be grateful to you.

  20. Magnificent points altogether, you just received a new reader. What might you suggest about your submit that you just made a few days ago? Any sure?

  21. aviation says:

    I have learn some excellent stuff here. Definitely value bookmarking for revisiting. I surprise how much effort you place to create any such magnificent informative web site.

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>