What Now, Terrafugia?

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Terrafugia's Long, Hard Road

So, Terrafugia..... The sort of things that I hear are: "Two words: Taylor Aerocar"; "So what? I'd buy a used plane for much less, carry four, fly there faster and pick up a rental car on the other end"; and "Do I really want to go find an A&P everytime someone uses their SUV to kiss the thing while they're parking?" And that's the polite stuff. But the fact is that there are people out there who like the idea, they like the people behind it and they're funding them. Honestly, I don't have much of an opinion about the vehicle itself, other than that it's a nifty collection of ideas and engineering. But if you'd like some insight into how a lot of money gets spent with at least little short term gain -- which, it should be noted, is mostly any research and design process in aviation -- this one makes a decent example.

Terrafugia used up a lot of money in the creation of an aircraft that serves as a proof-of-concept vehicle and, in practice, doesn't work all that well. As a start-up company formed mostly by freshly minted MIT engineers, it simply didn't have the resources needed to do the job right the first time. But even if it had, changes should be expected as they moved beyond the prototype. As it stands, the Terrafugia team has learned a lot about what they did wrong in building their first vehicle and seem to have found financial support to see them through creation of a V.2. Make of that what you will. In my opinion it's par for the course. The really interesting part is the back story.

When Terrafugia designed that first vehicle, Chief Technical Officer Carl Dietrich was fairly fresh out of his Ph.D. program and not exactly flush with cash. The original concept won a lot of attention and so became attached to a rough (if optimistic) progress schedule. It then progressed from the idea phase to the wind tunnel testing, but in the rush to meet publicly announced deadlines, manage its cash, and keep the media buzzing, some parts of the process may have moved a bit too far a bit too fast. Without the support of some of the resources needed to really do the job best that could be done, the vehicle became a reality. Unfortunately, it got there lacking three dimensional fluid dynamics software that might have disclosed the complex airflows that have placed the prototype closer to the barely flying realm of the aircraft spectrum.

In a refreshingly open and candid conversation I had with him, Sunday, Dietrich detailed some of the problems that has his company in redesign mode. First, the aircraft's heavy -- about 100 pounds over its LSA limit when loaded with a test pilot and test gear. The proximity of the canard and wheel pants disrupted flow over the canard's limited span, reducing lift that the craft recaptured only by flying with full pitch trim. At the same time, the vehicle is also producing more lift in its aft section than designers expected. In the end, those two aerodynamic effects together put the center of lift too far aft and that's why you see the vehicle flying with full pitch trim on the canard and near-full deflection of the elevator. It's also why you won't see the Transition fly this year at OSH and maybe never again until the redesign, which is currently expected to make its debut (in computer graphics form) in early 2010. It may arrive in physical form by year-end '10.

The fixes will redistribute the aft lift forward, and expand the distance between the canard and the wheel pants. All the airfoils are being tweaked and engineers are working to reduce the vehicle's overall weight. The first thing to go will be the stock cast iron continuous variable transmission that's currently in the prototype. There are a lot of hurdles yet to be overcome, and some of those are built by the natural skepticism of pilots. We'll see what happens. In the meantime, Terrafugia is undeniably bringing a lot of attention to general aviation and for a lot of folks, they're making the idea of aviation fun and exciting again. They deserve credit for that. They'll deserve even more if they pull it off.

Comments (7)

I observed this roadable aircraft prototype each time it was displayed at the airshows, spoke at length with the designers, read and viewed the performance.
Mr. Dietrich listened while I explained my experience as a test pilot and engineer with prototype canard aircraft and why they are not appropriate for the defined Terrafugia mission.
Simply put canard configurations demand too hot of a touch down for the Terrafugia mission.
Let’s consider some aerodynamic characteristics of canard aircraft:
Stall and recovery; as an airplane enters a stall the aft most lifting surface must stall last. In order to maintain roll control the wing (with ailerons) must stall second to last. This leaves the canard which must stall first. The result, by lifting surface configuration design, is the reduced ability to flair the aircraft resulting in a much higher approach and touchdown speed. All of which is dangerous and unforgiving.
I recall making final approach with 50 vertical feet to the runway when the canard abruptly lost its lift (stalled) at 65 kts which nearly dropped me on the runway while requiring full power to recover. The prop blast on the tail feathers was a life saver.
In a canard airplane it is necessary to always land well above canard stall speed.
My Opinion..

Posted by: Richard Meisman | July 27, 2009 8:20 AM    Report this comment

As much as I have thought about such a thing and have agonized over the problems, since watching the Bob Cummings show as a young man, I say kudos! Now for the BAD news. Automobile safety and now clean air regulations and FAA aircraft definitions and conditions conspire to doom such a project. To date, the only viable project I've seen is the Samson Motorworks. Only because it is a motorcycle and avoids auto regs. The FAA issue is still up in the air (pun intended). There seems a rush to fit LSA regs. Not bad but payload and range requirements are a REAL issue. If, somehow, you could fly to the patch, leave the airplane tied down, and drive around on the aircraft's "gear" and return for the hook-up the FAA might have second thougts. A weighty problem. Damn those puns.

Posted by: Larry Fries | July 27, 2009 7:15 PM    Report this comment

I don't know anybody involved in the project, haven't spoken to anyone involved, and have no money invested. But the project has my attention.
My wife (also a pilot) and I fly a Skylane, and find that we often wish we had a way to deal with the ground transportation for relatively short hops, an hour or less by air, to visit family or run shopping errands in the larger cities that are a one or two hour drive from the small town where we live. We would make these trips a lot more often with easier ground transport.
In the time we need to drive to our airport, pre-flight, fly, and then deal with ground transport at the other end, we can just drive and usually do. The ground transportation at the place we are visiting is the largest hassle and most time consuming, and this vehicle would eliminate that issue. So Terrafugia's got my attention, and I suspect there are lots of people like me out there.

Posted by: Richard Persons | July 28, 2009 11:46 AM    Report this comment

I’m the pilot with the 28 takeoffs and landings in the Transition. I see things differently than the conclusions in the blog. My view--why is it such a major deal that a proof-of-concept (POC) vehicle required more pitch-up trim and more up elevator than desired during the initial round of testing? Does it matter how it flew and landed? It rides very nice on the runway, handles decently in the air, and it is a very easy airplane to land.
The “issues” focused on in the blog are not big deals for a POC vehicle. The conclusions drawn (“doesn’t work that well…didn’t do the job right the first time…process moved to far too fast…etc”) don’t reflect how the POC vehicle worked. The two “issues” Carl was frank about have zero impact on an eventual production airplane…they are simply things that are being addressed in the design of the next vehicle. The POC test plan quantified these two issues so that we would LEARN for the next round of prototypes. That is the purpose of a proof-of-concept vehicle. And, It’s an aircraft that will fit in your garage, convert from car to airplane in 30 seconds, refuel at your local gas station, has car-door entry and exit, and has complete car controls and airplane controls so that any driver will be able to drive it and any pilot will be able fly it.
The Transition is a solid design and the POC proved the concept well. Colonel Phil Meteer (USAFR, Retired)

Posted by: Philip Meteer | August 6, 2009 8:13 PM    Report this comment

There is a reason why even small cars today weigh in at 3,500 pounds (DOT safety glass, bumpers, catalytic converter, etc). There is simply no way to put an airplane on the road and have it still meet LSA weight limits. Even most 2 place production airplanes can't meet the LSA weight limits!

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