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OWNER/BUILDER: Randy Brooks
REGISTRATION: NX24B
The Bratz (Brooks - Hatz) has been flown 64 hours since certification.
The Bratz is powered by a Lycoming 0-320A, 150 hp, turning a Sensenich W74-56
wood propeller, and equipped with Cleveland wheels with chrome discs and Maule
tail wheel.
The aircraft was flown to the National Biplane Fly-In at Bartlesville,
Oklahoma and to the Antique Fly-In at Blakesburg, Iowa.
Before I started my project I reviewed the plans (S/N535), observed and flew
other Hatz biplanes, and then decided to make several changes.
Modifications were made as follows:
- Aluminum ribs in wings and ailerons to
save maintenance and reduce labor in construction.
- Modified wing tips to reduce stalling
speed and reduce maintenance.
- Installed ailerons on only lower wings
to reduce number of parts. Ailerons were redesigned as friese
type 100% static balanced to reduce the chance of flutter and
reduce adverse yaw.
- The wing spars are 1/2" deeper due
to the use of aluminum ribs and all fittings were increased from
80 thousands to 90.
- Raised center section 2 inches with Stearman-type
cut out to give additional entry space for front cockpit.
- The lower wing dihedral was increased
to 4 degrees for lateral stability. Due to friese-type ailerons
and increase in dihedral, the Bratz in cruise flight requires
little or no rudder input for turns.
- The cabane struts were modified to provide
adjustment of stagger for easier rigging.
- Provisions were provided for ground adjustment
of horizontal stablizer so aircraft could be rigged for cruise
flight with elevator trim in neutral.
- A 15 gallon fuel tank was installed in
front of front cockkpit to give a total of 34 gallons of fuel
for the 150 hp Lycoming engine.
- Toe brakes were installed in both cockpits
at the request of wife who holds a private pilot certificate.
Cessna 140 type pedals were used in front and my own design pedals
in rear.
- Landing gear was lengthened three inches
to allow for slower landings.
- Aluminum panels were installed from firewall
to the aft cockpit to prevent fabric damage around cockpit area.
It also decreases fire hazard.
Performance figures after
64 hour of flying
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Take-off distance |
300 feet |
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Landing distance |
400 feet |
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Stall speed |
40 mph |
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Approach speed |
60 mph |
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Rate of climb |
800 fpm @ 70 mph |
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Cruise speeds |
88 mph @ 2300 rpm
95 @ 2400 rpm
105 mph @ 2500 rpm |
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