This
promising concept has been going a while now, but as yet does not
seem to have come to fruition.
One of the primary design objectives was a 210 mph plus, long
distance cruising machine. Having 450 HP
available in a reasonably light aircraft for its size is certainly
an asset in achieving the desired performance goals. The low power
loading numbers translate into fairly impressive short field
take-off capability and climb performance. Performance estimates
predicted the design goal of 210 mph cruise at 75% power at 9000
feet. Drag data computed from stock G model Staggerwings and
statistics from typical, current generation, composite aircraft
predicted fairly impressive top speed numbers. The design dive speed
is 320 mph. Stall at gross is about 56 mph with flaps deployed and
67 mph retracted. The low stall speeds are a result of the wing
area, and the four plain flaps. Rate of climb with the aircraft
lightly loaded is quite spectacular. Climb analysis computes a 3200
fpm climb rate at 65% gross weight and 1900 fpm at gross.
The Pratt & Whitney R-985 Wasp
Jr. engine is a derivative of the Pratt 1340 cu. in. Wasp engine.
This engine is currently flying on numerous antique aircraft and
has seen extensive use in the agricultural aerial application
industry. The R-985 has a remarkable history as a durable and
reliable source of power. Although no longer in production, there
exists a sizable inventory of these engines in circulation with
many becoming available as agricultural planes upgrade to
turbo-props and Beech 18's are removed from service. New and
surplus parts are readily available to support replacement of
essentially all engine components. The R-985's ability to burn
auto fuel makes it an even more attractive powerplant.
Lionheart is a modern derivative of the "Learjet
of the 30's", the Staggerwing Beech. The negative stagger biplane
arrangement provides numerous advantages, some aerodynamic and some
construction related, but also represents a classic elegance not
duplicated until now. A Pratt & Whitney R-985 radial engine was selected
for the baseline design as a plentiful, reliable, and low cost
horsepower/dollar powerplant that ultimately inspired the overall
Lionheart configuration. Lionheart's overall size is very similar to the
stock Staggerwing, but the cabin interior is lengthened slightly to
provide Baron class 6-place seating.
The Wing System: The biplane wing system provides adequate wing area
necessary for the desired low stall speed using a simple flap system.
Lionheart's wing area is about 20% less than that of the Staggerwing
because it's empty weight is lighter by about 600 pounds. A low stall
speed was one of the key design requirements to provide relatively low
energy, emergency, engine-out landing capabilities. Some maximum speed was
sacrificed to achieve this goal, but this compromise gives comfort to
those of us who are safety conscious. The builder will have to make twice
as many wings but they will be easy to assemble and relatively small
(about 13 feet from wing root to tip). Unlike the Staggerwing, both wings
are cantilevered, so no struts or wires are necessary. Laminar flow
airfoils are used on all wing surfaces. The wing root airfoil is a modern
derivative of the 64-215, tapering to a 64-212 at the tip. No washout is
used in the wings because of the "canard-like" stall characteristics of
the negative stagger arrangement. Due to the induced airflow from the
lower front wing, the top wing is flying at a slightly lower angle of
attack during a stall. This means the front wing unloads before the top
wing resulting in a gentle nose down at the stall break. The stock
Staggerwing's gentle stall characteristics are due to this well known
effect.
The Cabin: The fuselage is about 20 feet long
from firewall to rudder post making Lionheart a cabin class aircraft that
can be constructed in a relatively small space. Interior cabin volume and
seating is similar to the Malibu but wider at the shoulders. Cabin width
at the pilot/copilot seats is about 50 inches and widens to a maximum
width of 51 inches near the second row of seats. Cabin width at the aft
seats is about 42 inches. Cabin height at the pilot/copilot seats is about
52 inches and tapers to about 42 inches at the aft seats. A small aisle
exists between the first two rows of seats. Cabin access/egress is via a
single split door between the mid and rear seats on the left side of the
fuselage (ala Malibu and Staggerwing).
Lionheart has been designed to accommodate 6 full size, FAA 170 lb
passengers, but a 95% human model (6'-4") was used to verify interior
space for the pilot/copilot. The aircraft is designed with a 4200 lb gross
weight at +6,-3 G limit loads. Following structural testing the gross
weight is increased for +4.4,-2.2 G limit loads (utility category). With
an estimated empty weight of 2250 to 2300 lbs, Lionheart has a payload of
about 1900 lbs. Just about right for the wife and kids... and lots of
fuel.
Controls: Dual control sticks are designed for the pilot and co-pilot
seats. Ailerons and elevator are pushrod actuated while the rudder is
cable operated. The four ailerons and flaps of the upper and lower wings
are interconnected at the wing roots via cables. With the exception of the
landing gear attachment fittings, the upper and lower wings are identical.
Landing Gear: Lionheart uses a fully retractable conventional (taildragger)
landing gear. The mains use pressurized gas for spring and damping while
the tailwheel is sprung via a gas charged air/oil cylinder. Retraction is
accomplished using electro-hydraulics. Landing gear track and wheelbase
are both wider and longer than the stock Staggerwing, so ground handling
is improved.