An Automobile Company Designing Airplanes

Automotive giant Honda Motor Company caused a sensation in the aviation world last year when it threw its hat—and considerable reputation and resources—into the business jet ring with the eight-seat HondaJet, for which the new Honda Aircraft Company in early 2007 had more than 100 orders. At 483 miles per hour, the HondaJet is the fastest aircraft in the light jet class (under 10,000 pounds) with a respectable 1600-mile range, a performance advantage designer Michimasa Fujino credits to its natural laminar flow wing and unusual placement of the engines: on top of the wings. Air & Space Editor Linda Shiner spoke with Fujino in February 2007.

A&S: Why did an automobile company like Honda begin a project to design an airplane?
Fujino: In 1986, Honda started the new fundamental technology center. There were several projects: airplane project, jet engine project, and humanoid robot project. I was called by my boss to transfer from the automotive division to the airplane division.

A&S: Were you happy with the transfer?
Fujino: At the time, I was surprised. I didn’t expect Honda to start an airplane project.

I graduated in aeronautical engineering from the university, but in Japan there is no major aerospace industry, so it’s not so exciting in Japan so I had decided to commit myself to work on the automobile when I decided to join Honda. At first I tried to decline the transfer. I wanted to work for the automobile division. But company is company, so I was automatically transferred from the automobile division to the airplane project.

A&S: What was your first project?
Fujino: The first project was to build the experimental aircraft called MH-01. The MH stood for Mississippi Honda. Honda partnered with Mississippi State University in a project to modify an existing airplane—a Bonanza A36—with composite material. We purchased the airplane, and we replaced the wing and empennage with composite material. We completely modified the airplane [at MSU’s Raspet Flight Research Laboratory] and compared the weight, structure, and flight characteristics [with those of an unmodified Bonanza].

Honda management was looking for a place where we could fabricate an airplane and conduct flight testing in the United States. They were seeking for many possibilities—to work with a company or a university. The company wanted to work with a university rather than a company because a university could keep a secret better. And the facility was unique; even though it’s a university, it’s just like a shop where you could build an airplane. This kind of facility was only at Mississippi State.

A&S: Did you work alone or with a team?
Fujino: Five engineers were sent to Mississippi State Raspet Flight Research to build airplane by ourselves with some support from technicians in the United States. But we fabricated the airplane by ourselves and learned by ourselves.

A&S: Had you had experience in composite fabrication?
Fujino: No, I majored in airplane stability and control, so my background was more theoretical. I studied aerodynamics. In Japan, it’s hard to get [practical experience] with an airplane. I had never touched an airplane before. So when I went to Mississippi State, it was the very first time I had the opportunity to touch an airplane—and it was a very different experience.

It was kind of interesting, but for the entire first year, I was just sanding a mold. So at the end of the one year, I thought it was a very hard experience, a very hard job, from a physical standpoint. Long hours and more like fabrication.

At first I didn’t see that fabrication itself would be so important for an airplane because I majored in very advanced theory at the university. But after I learned to fabricate the airplane on my own, I started to understand the importance. Until I understood the importance of building the airplane by my own hand, that experience was a very tough experience for me. But now when I take a look at a part, I can read it: I know the proper weight and thickness. So sometimes those experiences are very pure. Many designers in the United States do not have experience in building parts by themselves. So now when I take a look back at my experience, I think it’s a very good combination with theory and practical fabrication. It’s very helpful for my airplane now.

A&S: How did that experience contribute to your next project?
Fujino: After I learned the very basic process of making an airplane, we tried to explore a much more advanced technology by building a more advanced airplane. The MH02 is actually the first all-composite business jet: The fuselage, wing, everything is made of composite materials.

A&S: When you were working with the fabrication of composites, did you at that time believe that you would be designing a new airplane from composites?
Fujino: I was the youngest member of the team and was treated like a technician there. So I didn’t expect that I could design an entire airplane. But after I gained experience—and in combinaton with theory and practical experience—it helped me a lot to understand many design options.

The MH02 had a forward swept wing. We tried many technologies on this; it was an experimental aircraft. We explored the application of these technologies to a small airplane.

We fabricated and assembled the airplane by ourselves and conducted flight test by ourselves, from theoretical design to publication and flight testing. We studied sophisticated techniques. And that was a very important step for Honda to establish all design techniques or theories. That was the foundation to go into the HondaJet.

A&S: Who determined the technologies you would test?
Fujino: At the time, there was a project leader. He had the concept; my role was to realize the concept from a practical design standpoint. He gave me the concept, and I made a sketch for him. My boss was a very good engineer but he didn’t have an aerospace engineering experience.

A&S: What was it like living in Mississippi?
Fujino: It was very different from Tokyo. I didn’t know the United States very well. I had never been abroad. So from television, the image of America is New York or Los Angeles. When I went to Mississippi State, it was a kind of culture shock—only three traffic lights in the main street. But the costs to live were very low. My apartment was three or four times larger than my Tokyo apartment.

It was a good experience for me; there is so much diversity in America. I enjoyed the Mississippi State people; they are very friendly. And sometimes I went to Jackson or Atlanta, and that was a very good experience for me to see the difference between city America and country America.

A&S: What do you think was the biggest adjustment you had to make?
Fujino: There are many small things. The first obstacle for me was that I couldn’t understand Southern accent. If I went to a hotel, I couldn’t understand what those in the service industry said. So communication was very difficult for me. And also there are no Japanese there: so no Japanese food, no Japanese culture. So that was a little bit difficult. But at the same time, that was good for me—to explore American society.

At the time, from Columbus [near Mississippi State] to Atlanta and from Atlanta to other small cities, I have to change airplane at a major hub airport like Atlanta. So I began to understand that from small airport to small airport, transportation is very important. If I use a small airplane from small town to small town, it is very convenient and it saves a lot of time. That kind of image [would have been] difficult for me to understand if I lived in Japan. [There] I didn’t use a small airplane at all. Also the traffic control system is completely different. But in the United States, using a small airplane is not so unusual. I could understand the future potential of a small airplane in the United States, especially when many cities are distributed all over the nation.

Also, sometimes in the United States, even a small city has a business. In Japan, the many corporations concentrate in Tokyo. But in the United States sometimes many enterprises are distributed all over the nation. So transportation is very important.

Also I understand the individualism and independence of operations are very important in the United States. In Japan, when I worked in the automobile division, for the drawing we used a main frame, centralized computer. But when I came to the United States, even in Mississippi State, each student has a personal computer.

There is a lot of freedom and potential for even a small company or organization able to design an airplane. That is a very big difference from Japan.

A&S: Did the MH02 have its engine located over the wing?
Fujino: Yes. The first experimental aircraft design was for an Advanced Turboprop—ATP—with very small diameter. The design was based on the pusher configuration, so you may know that the engine is mounted on the wing in a pusher configuration. But during the development of the Advanced Turboprop design, the [ATP engine development program] was terminated. Finally I was asked to change the engine from the ATP to an existing fan engine by my management. So we finally decided to use an existing engine from Pratt & Whitney. I was looking for a position where I can install the engine on the airframe. I tried many configurations. At the time very small engines were not available, so we had to use a large engine, which was a little too big for the airplane. As a result, there were many geometrical contraints. So, at the end, there was only one place where we could install the engine: over the wing.

But that design gave me a lot of design inspiration for the HondaJet because some technical aspects are very similar. I developed many analytical methods to design this configuration from an aerodynamic, structural, and aeroelastic standpoint. With the MH02 experience, I started to explore new configurations for the HondaJet.

A&S: Most aerodynamicists would worry that an engine mounted on top of a wing would produce too much drag.
Fujino: Right. It’s common sense in the airplane industry never to put anything on top of the wing because aerodynamic interference cases a drag penalty esecially at high speed. Also this configuration cases a loss of lift if it is not properly designed. So first I tried to minimize these disadvantages. Frankly speaking, the original MH02 is still facing some drag penalties at high speed because of the over-the-wing configuration. There was also some lift disadvantage as well. But the MH02 is a very low speed airplane: .5 Mach number—so the penalty of over-the-wing engine mount configuration is small and acceptable. When I started designing the high-speed HondaJet, I tried to create the best over-the-wing engine-mount configuration which minimizes drag at high speed and also minimizes lift loss. After I conducted extensive analyses and testing, I found the optimum location of engines relative to the wing, which gives higher efficiency than that of a conventional configuration by employing the new concept of favorable interference. As a result, HondaJet’s optimum over-the-wing engine mount configuration actually achieves lower drag and higher efficiency at high speed.

A&S: How did you get from the MH02 to the HondaJet? Did the company say, “Okay, make us an airplane?”
Fujino: It was a very difficult transition from the MH02 to the HondaJet. When the MH02 project was finished in 1996, the management gave up the airplane project. At the time the automobile industry was very competitive, and Honda was trying to be very competitive from a technical standpoint and marketing standpoint.

A&S: How did you feel about the company’s decision not to go forward with the airplane project?
Fujino: Of course, I was very disappointed because I had worked for almost 10 years on the airplane project. And I worked very hard to realize or make a foundation in Honda to build an airplane. And I thought my effort might be in vain if [the company walked away from airplanes.] So I wanted to continue and I wanted to build a new airplane. And also, after 10 years of working with American engineers and friends, I had confidence that I could build a much better airplane than existing airplanes. Combined with some confidence and passion to continue the airplane project, I decided to propose a new project, the HondaJet project, to management in 1997.

In 1996, our project was finished. It took me six months to a year to find an opportunity to propose the project to our top management.

A&S: What was your proposal?
Fujino: At the time, I found the oppportunity to talk with the president of the Honda Motor Company. I explained the future possibility of a small business jet. I explained my own practical experiences in the United States. Without that experience, it is very hard for an engineer to build a new product.

One advantage for a Japanese to design very good automobile is that all engineers drive cars themselves. They’ve owned automobiles, and they understand the need of a customer—the importance of the quality and of the performance and reliability. Those are very good feedback to the design. But for airplane, very few Japanese have the experience to use an airplane. So it’s sometimes very hard for them to understand how much potential exists in the small airplane market. Fortunately, I worked in the United States more than 10 years, so I tended to understand the American people’s lifestyle, culture, and the importance of small airplane transportation.

A&S: It seems like a bold move for Honda. Do you think the boldness was attractive to the President of Honda Motor?
Fujino: Actually, many of the board members were skeptical about the airplane project, but traditionally the president of Honda Motor comes from engineering background, and Honda is the kind of company that understands the product very well. Many Western companies are run by financial people. But in Honda’s case, the substance of the business is to build the best product and to sell with honesty or to sell with quality. That is the kind of circumstance of the business. And from such point, the president thinks we have to explore more long-term markets. Of course Honda’s looking at 3 years [out] and 5 years [out]. But we’re also looking at 10 years and 20 years as well. They just don’t concentrate on 3 years or 5 years only. Very few but some in management still have a very big picture. There are some broad-thinking people. They have a very good balance between a short-term business and a long-term business.

I think at the time [I made my proposal] the president had understood the future of mobility and his responsibility as a mobility company. He understood that a small airplane was a good thing to be pursuing.

A&S: Did the president say yes right away?
Fujino: Actually, he took about 30 minutes. But maybe he understood not only the potential of the market, but my enthusiastic explanation.

A&S: Did you expect when you began working on the over-the-wing engine mount for the HondaJet that you would need to find an optimum position, a “sweet spot” as you’ve called it?
Fujino: My first goal was to find the position which minimized the penalty, so at the time, I didn’t think we could turn [the configuration] into an advantage. After many theoretical studies, I found an optimum sweet spot, but at the time, we had not conducted experiments, so I could not hundred percent believe the result; it was only theory. So I decided to conduct experiment by using wind tunnel. And wind tunnel test results validated my theoretical concept.

A&S: When you tested your 1/8 scale model at the Boeing Wind Tunnel facility, what were the reactions to your over-the-wing engine mount?
Fujino: Yes, you know the Boeing engineers are very professional and very nice people, so they did not directly say this to me, but I heard them whispering, “This is a very bad design. He obviously doesn’t know anything about airplanes.”

But after a week or so, they started to understand that we understand what we are doing. And also they took a look at some of the data. They were kind of impressed that we were doing very sophisticated things. So they changed. And at the end of the tests, we had dinner with them and they said Honda people are really smart.

A&S: With these tests, were you also refining the shape of the pylon?
Fujino: The first concept was the nacelle position. So we didn’t concentrate on the shape of the pylon too much; our research concentrated on the position of the engine first. But also, if you mount an engine on the wing, you have to have a pylon structure or support structure. And that is also very critical: the shape of the pylon and nacelle configuration is very, very critical. There are many design constraints in the pylon. First, the pylon should not produce any side force. If it produces a side force, that causes a drag penalty. I tried to find a very sophisticated shape not to produce the side force. And also the pylon shape is very important for the stall characteristic. I checked the best pylon shape from a high-speed standpoint and a drag standpoint and the stall characteristic standpoint.

That’s why, probably you noticed, that the pylon is uniquely curved.

A&S: It looks a little like a wing standing on its side.
Fujino: Right, right. That shape comes from those detailed design studies.

A&S: Then you put that in the wind tunnel and discovered…
Fujino: First that the pylon and nacelle shape were giving us a very high-divergence Mach number. [That means that a sharp increase in drag, associated with local airspeeds approaching Mach 1 was delayed; the aircraft could fly faster—closer to Mach 1—before encountering the drag penalty]. When you see the HondaJet, you will notice the unique shapes of pylon and nacelle. They were designed to delay the increase in drag caused by the compressibility effect.

We also discovered that pylon shape and spanwise location gave us better stall characteristics than those of a clean wing. So the maximum lift is even slightly higher than that of a wing without the engine mounted.

A&S: What has been the reaction to the wing-mounted engines?
Fujino: You know, when I designed the over-the-wing engine mount configuration, even after I could prove some advantage in performance with data from tests, people continued to say that even if the performance is good, over-the-wing engine doesn’t look cool. They said it looks very ugly. The first time I proposed over-the-wing configuration, everybody said, this is not a good idea from a technical standpoint. And when I proved the technical advantage, they continued to say that it’s a very ugly airplane. But when we pulled the airplane from the facility to the outside, people were very impressed and said “Hondajet looks very good.” And every time the engineers see the airplane, they come to like the pylon shape more and more. And actually one of the technicians said to me that what he likes most of the airplane is the pylon.

You know, when you meet a person, your first impression of that person may not be great, but you grow to like that person more and more when you know him better. Over-the-wing engine mount configuration may be similar because now nobody says the airplane doesn’t look good. I like it most when everybody now says, HondaJet is a beautiful airplane. When people put the word “beautiful” in front of HondaJet, that is the best compliment for me now.