About The New LH-10 Ellipse

(Monday, we introduced you to a new homebuilt aircraft, the LH-10 Ellipse from LH Aviation. This two-place aircraft is a dream to look at and promises a top speed of 200 knots. We asked 20 questions of company co-founder Frederic Hubschwerlen. In this first of a two-part series, here are the first ten. -- ed.)

1. ANN: What inspired the LH design team to create the Ellipse?

Frederic: The main idea behind the Ellipse concept was to design an airplane that would suit the needs and wants of 21st century private pilots. We had several market studies done, and the logical solution was the LH-10 Ellipse. We were able to clearly identify the key features of the airplane : size, speed, range etc… from our analysis of the pilots’ needs. It will be fast, fun, versatile, efficient and very cheap to operate. Flying at 100 kts on less than 2 GPH will probably be attractive to many pilots. Moreover, with a top speed of 200 kts, the LH-10 Elllipse can be used for fast trips.

2. ANN: The LH-10 has been in development for about a year. How were you able to reach the prototype stage so quickly?

Frederic: Indeed, designing the LH-10 Ellipse and building most of the tooling took less than a year. The design of the LH-10 Ellipse was done using very advanced methods, starting from a basic concept and evolving through dozens of iterations. Thanks to the use of state of the computer assisted design software, we were able to push these iterations very quickly. For example, we could choose to modify some part of the airplane, then redraw all the plans and estimate the impact on the aerodynamic, structure and production methods. And all this could be done in a few hours thanks to our computers. All the aircraft and plans being modeled in 3 dimensions, we have a virtual prototype built, and all the assembly methods of the first prototype can be tested. We can thus forge ahead very quickly with the prototype construction. The plug and moulds were built by Mascotte BVBA in Belgium. Mascotte has huge experience of prototype and moulds building, and they use very simple, cheap and clever methods. The plugs were entirely build by hand, and the finish is to be seen to be believed ! Advanced, efficient design and prototyping methods is a must for LH Aviation. The LH-10 Ellipse development lead to a very advanced design though keeping the cost low.

3. ANN: The Ellipse has a very wide speed range. How were you able to accomplish that?

Frederic: The LH-10 Ellipse has three secrets: First, a very small, light and clean airframe. The LH-10 Ellipse, despite it’s tandem seating configuration, is very short. In fact, the wetted area of the airplane is about 50 percent less than other two seat airplanes. As a result, the drag is dramatically reduced, and the airframe is extremely light. However, the LH-10 cockpit is very roomy and comfortable. Thanks to this low empty weight, a very small wing can be used, thus again reducing drag. A thorough optimization of the design: the use of advanced computer assisted design solutions enabled us to deeply refine the LH-10 Ellipse design very quickly and efficiently. These methods pointed out the need to use an efficient pusher propeller and a light drive shaft. This configuration is only marginally heavier than a conventional tractor, and can reduce drag up to 25 percent.

A very efficient wing: The LH-10 Ellipse uses a high aspect ratio wing with a custom designed airfoil that perfectly fits the typical LH-10 Ellipse flight envelope. This wing has an excellent lift to drag ratio at high speed. Despite a high wing loading (meaning a good behavior in turbulences) the stall speed of the LH-10 Ellipse stays low.

A very efficient high lift device is used: full span slotted flaperons (actually external airfoil flaps). Through hours of computer and wind tunnel testing, we were able to optimize this design in order to produce an extremely high lift coefficient that is usually found only on airliners or some aircraft using complex fowler double slotted flaps. The external airfoil flap is much lighter and more reliable than these designs. An other strong point of the LH-10 Ellipse is it’s exceptional thrust to weight ratio. With a medium sized pilot and one hour of fuel, this ratio is only slightly below one, making for some very exciting acceleration performance.

4. ANN: The Masschi engine seems remarkably capable, given its limited horsepower. How revolutionary is the design of this engine?

Frederic: The Masschi 105 is indeed a very promising engine. However, it follows the same basic philosophy as the LH-10 Ellipse. It is small, light and efficient. It is a conventional 4 stroke flat four, but thanks to unusual crankshaft design and valve position, it is very small. Overall component optimization using CAD and careful choice of materials –- including high strength aluminium and carbon fiber with high temperature resins – contribute to an exceptionally low weight. One other strong point of the Masschi 105 is it’s liquid cooling. This increases reliability by efficient, uniform cooling, and reduces cooling drag.

5. ANN: What is the status of engine testing?

Frederic: The engine testing will begin in August 2004. The engine will be ground tested for at least 200 hours before going to full scale production. This engine will of course be available for other airplanes.

6. ANN: You're debuting the LH-10 at the Avia Expo. When do you anticipate first flight?

Frederic: The first flight of the LH-10 Ellipse is scheduled for the end of this year. Our goal is to have the test program completed by the Friedrichshafen Aero show (the biggest in Europe) next year.

7. ANN: What is your testing schedule?

Frederic: The aircraft will be tested to conform the FAR-23 requirements, though no FAR-23 certification is planned at the moment. We are building two prototypes, one of which will be destroyed for structural testing purposes.

8. ANN: What will the kit look like when you present it to buyers?

Frederic: Our goal is to make the LH-10 Ellipse kit easy to build for everyone. The kit will conform to the 51% rule. It will include all parts needed, from the engine to the smallest bolt. The overall project cost will thus be very easy to estimate. That way, we'll all save valuable time in the tedious part sourcing process. Most of the difficult work will be done. The fuselage halves will be bonded, the firewalls, wing carry-through and fin spars glued. The wing spar and wing ribs will be bonded to the upper wing skin. The kit will include a detailed builder’s manual, complete with technical drawings and construction photos.

9. ANN: Please give us some details on the construction support LH Aviation will provide to purchasers of the Ellipse.

Frederic: During the early design if the LH-10 Ellipse, we attempted to identify and overcome the main reasons why people are reluctant to build or fail to complete kit airplanes. Our answer to this problem will be our builder assistance program. LH Aviation will offer three different services packed into this program. First, we will offer hangar space and tooling so that people can build comfortably and efficiently. All jigs and special tooling will be available, saving hours of work. Second, builders will benefit of the expertise and advice of the engineering time, only a few minutes away. Last, as there will be several LH-10 Ellipse builders in the same workshop, first hand experience and encouragements will be easily available. This program will first be available in our Merville facility, but we plan to extend it to other countries through a LH Aviation authorized reseller network. Of course, this program is optional. A builder can choose not to use it, or to have only some construction steps done with the assistance program. However, given the time and money saving, we recommend to use it.

10. ANN: What is the amount of time a kit builder will need to complete construction?

Frederic: The LH-10 Ellipse is designed to be an easy, quick built kit. However, we don’t want to announce some unrealistic building time. A provisional amount of time will be published when the first LH10 Ellipse are sold, but we’ll update this figure as we gain more experience with various builders.

FMI: www.lhaviation.com