Sig Demoiselle RC Plane Kit


Sig Demoiselle RC model plane

Front view of the Sig Demoiselle

The Sig Manufacturing Company’s Demoiselle offers an exceptionally well designed and carefully engineered kit of an historic aircraft. As an added bonus Sig’s sport scale Demoiselle flies remarkably well and will be a welcome addition to your radio control flying fleet.

The Demoiselle was first flown in 1908 by the pioneering Brazilian

Demoiselle airplane

Demoiselle aircraft in flight

aircraft designer and pilot, Santos Dumont. Recall that the Wright brothers performed their first flight in 1903, a mere four years prior to the Demoiselle’s debut. Engines at that time were heavy and did not produce much power. The original two cylinder engine of the 1907 Demoiselle generated only 20 horsepower. Innovative strategies were required to build a successful aircraft.

Design approach

Santos Dumont took the design approach of creating a smaller aircraft to achieve as light a flying weight as possible. The Demoiselle’s low weight permitted the use of unique building materials, such as bamboo, in the aircraft’s construction.

The original aircraft had an open fuselage frame with fabric covering on just the wings and tail surfaces. The pilot sat within this fuselage frame directly under the wing. This layout provides the Demoiselle with a unique look, but the open fuselage frame provides a challenge to the RC plane designer as there are no obvious places to locate and conceal the receiver, battery or servos.

Sig Manufacturing did a remarkable job meeting the challenges of creating a kit of this one of a kind aircraft. The kit comes with

RC servos

Demoiselle tail control servos

all necessary parts and accessory items needed to construct a strong and light weight semi-scale replica of the original airplane, to include the electric motor, prop and balsa wood wheels. The building instructions are clear and well documented. I would advise that anyone planning on building a Sig Demoiselle ensure that they are comfortable reading a set of construction plans and have completed building two or three models from other kits.

Kit details

The kit includes a photo illustrated construction manual that must be studied and closely followed. Sig also supplies detailed full size plans. Sig outlines some construction techniques that I have not encountered in over 38 years of designing, building and flying RC model aircraft that are innovative, carefully thought out and just what is needed to replicate the Demoiselle.


Demoiselle RC airplane kit

Demoiselle ready for flight

The model goes together quickly and in a logical fashion. I especially like the method of using metal tubes and balsa dowels to anchor the removable wings to the fuselage frame. The two tail control servos and receiver are artfully hidden in the Demoiselle’s upper wing joint area and connect to the tail via fishing line filament.

RC airplane electric motor and prop

Geared electric motor comes with the kit

As you build any model airplane kit, be on the lookout for useful construction and design innovations for adaptation to your designs. For example, I incorporated the Demoiselle’s metal tube wing mounting technique to my designs of the Chickadee and Blackburn. CAD plans for these two aircraft are available here.

The Demoiselle employs an all-moving tail plane that combines the functions of elevator, stabilizer, rudder and fin in the same unit. This tail section is faithfully replicated in the model and does a great job providing smooth and positive flight controls. By allowing the entire tail unit to move the Demoiselle has a greatly improved control surface effect that matches well with the high drag and slow airspeeds inherent with the aircraft’s flight regime. This tail design would be an innovative approach if taken today, let alone in 1907.

Flying the Demoiselle

As a result of the large, high lift wings the Demoiselle handles differently from just about any other RC model airplane you have flown. The construction manual has a thorough discussion of these special flight characteristics. Carefully study this section as all the instruction points are spot on. The Demoiselle is a steady and predictable flyer, but it is not a trainer. You should be comfortable flying a normal, electric powered sport RC plane before learning to fly the Demoiselle.

Before your first takeoff ensure the battery is fully charged and check that the tail moves freely and in the correct direction. Confirm you have plenty of control throw, at least an inch in each direction. With the Demoiselle’s slow fight speeds you really cannot over control or stall the model.

Demoiselle RC model airplane kit

Front view of the Demoiselle ready for a flight

For your first practice flights perform a series of short straight ahead hops. You will quickly gain a feel for how power management controls altitude. The Demoiselle’s wing incidence and motor down thrust is set such that at full throttle the Demoiselle will climb, mid-power will maintain altitude and at a low throttle setting the aircraft will descend. The Demoiselle’s elevator has much less impact with maintaining altitude than with other model planes.

You will find that after several practice hops that you obtain a feel for the predictable handling characteristics of this one of a kind model. Turns are quite easy and the large size of the Demoiselle makes it easy to keep it in sight while in the air. As outlined before, power is used throughout the flight to control altitude. Elevator is used to aid initial lift off and to help with the landing flare.

The Demoiselle takes off in a matter of a few feet and starts a slow climb to its normal flight altitude of about 10 to 15 feet above the ground. Due to the aircraft’s large wing surfaces and light weight, the model has a narrow speed range between full power and a normal cruise power setting. Control is effectively handled by the all-moving tail that provides positive and precise aircraft pitch and steering control. The plane flies at the pace of a fast walk and is positive and crisp in response to flight commands. You will soon get very comfortable with actually “watching” the effects of your flight inputs.

The Demoiselle can be flown indoors or outside under calm wind conditions. The large and lightly loaded wing surfaces are unable to counter the wind gusts normally handled by faster, heavier aircraft.

Landing the Demoiselle is a learned skill. A slight reduction in throttle starts the descent. The model will “drive in” to the landing with full control to touchdown provided by the large tail surfaces and fairly high power setting. Again, be sure to follow Sig’s instruction manual for specific training maneuvers to develop your landing skills.

Sig’s Demoiselle is a remarkable kit of a noteworthy aircraft. It is well worth your time to build and fly this model plane and capture some of the feel of the first days of manned flight.

Author:  Gordon McKay