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.