PreciousF3B

About Precious

Precious is high performance F3X glider. Used technologies and all characteristics predetermine this glider for F3B and F3F categories. Model is completely hollow molded in CNC (Computer Numerical Control) molds. Basic design is result of cooperation between Breta Models Ltd. and Norbert Habe. Both partners used in Precious project long years experience in F3X field.

Precious is six channel glider with single dihedral and V-tail concept. For wing production is used as standard high-density Herex or Rohacell foams with several glass/carbon layers. Wing main spar is produced from carefully selected balsa wood which offers huge stiffness and low weight. V-tail is produced using same technology. Fuselage is combination of Kevlar/carbon/glass technology. There are several carbon roving stripes in heavy loaded parts. Especially in wing joiner area, we use special glass pushrods covered by low-friction tube in bowden housing.

Whole model is supplied inclusive wiring (fuselage and wing servos) with JR/Graupner connectors at one end, Multiplex green female/male connectrors for wing/fuselage connection. Ballast is standard part of accessories.

Standard flying weight is approx. 2200g. Using simple ballast system in fuselage you can reach flying weight approx. 3800g. That's nearly 59g/qcm. Expected to be enough for any wind conditions.

Precious

Precious - Finishing

It's good idea to weight standalone model parts before building. It will maybe help you for later reference or model comparison. We will start model completion with fuselage. Solder supplied cables on green multiplex female connectors in wing . We can also complete cabling in fuselage incl. switch and charching Rx battery connector.

Protect all soldered parts with heat-shrinking tube. Laydown antenna in fuselage, let aprox. 10cm of wire more on both ends. It's recommended to prolong Rx aerial to one v-tail ends. For prolongation we don't use any connector. Wires are soldered nearby v-tail ball arms. Use only high quality receivers (PCM/SPCM/Double Conversion). Male Multiplex connectors are glued in fuselage using CyanoAcrylate (CA). Don't glue female part in wing yet.

Fuselage cabling Using thin piano wire Rx aerial is prolonged to left v-tail half. Soldered nearby v-tail ball armys with main aerial in fuselage
Fuselage cabling Using thin piano wire Rx aerial is prolonged to left v-tail half. Soldered nearby v-tail ball armys with main aerial in fuselage

Plywood servo seating. Before glueing servo seating in fuselage we should consider ballast tube position while it's also glued in servo seating. Center of ballast tube should be aprox. 2-4mm behind expected Center of Gravity (CG). CG recommended position is 101-106mm from wing leading edge. Sure CG is very personal matter, it's up to you what you prefere. Ballast tube input should be big enough and without servo pushrods obstruction. Also check all holes in plywood bulkhead and components used by you (Receiver, servos, switch). Be aware if nos lead will go through bulkhead. You will need aprox. 140g in nose for CG aprox. 102mm using Graupner/JR receiver DS-19 and pair of JR/Graupner servos DS3781. Plywood servo seating glue using high quality epoxy resin. It's also good idea to reinforce fuse/bulkhead corner with carbon roving. Ballast tube should be glued after complete model setup.

Ballast tube center and CG position with brass ballast segments Servo seating
Ballast tube center and CG position with brass ballast segments Servo seating

Fix carbon v-tail pins in fuselage. Usually it's enough to use only first two pair of pins. It's better to fix pins in fuse using some slow curing glue (epoxy) while CA can immediately block pins somewhere in first mm position. Mount v-tail servos, fix v-tail and cut pushrods to appropriate length. Fix blue pushrods tubes in fuselage, especially longer one.

Place carbon v-tail pins in fuselage Fixed longer pushrod
Place carbon v-tail pins in fuselage Fixed longer pushrod

Wings. Cut supplied wires and solder it with appropriate servo connectors. We prefere connectors, in case of emergency we can just swap whole servo and continue flying. Solder wire ends to green Multiplex female connectors. These connectors are fixed in wings using epoxy glue. Use separator (petroleum jelly) on fuselage around female connector part. You have to glue male connector with wing joiner in fuselage.

Cut servo cables. heat shring all soldering points Fixing servos in wing
Cut servo cables. heat shring all soldering points Fixing servos in wing
Male connector Using petroleum jelly separate fuse central part before glueing female connector seated in wing
Male connector Using petroleum jelly separate fuse central part before glueing female connector seated in wing

Using plaster make small nose cone lead mold. As was metioned above, you will need aprox. 140g nose lead ballast. For first starts we recommend CG around 101mm. Go rear if you are experienced pilot. After complete model setup we can glue in ballast tube. Ballast tube end with carbon pin fix in fuselage using a piece of foam soaked with resin.

Plaster nose lead mold Ballast tube input
Plaster nose lead mold Ballast tube input
Ballast tube nut Fix ballast tube in fuselage using piece of resin soaked foam
Ballast tube nut Fix ballast tube in fuselage using piece of resin soaked foam

Precious - Setting by Fidel Frick

seting CG FLAPS
AILERONS
ELEVATOR
RUDDER
A 106
- 2
- 2
+ 0.5
0
B 106
+1
+1
0
0
C 106
+ 2
+ 2
- 1
0
START
- 14
- 14
+ 1
0
BUTTERFLY
- 54
+ 11
- 5
0
deflections CG FLAPS
AILERONS
ELEVATOR
RUDDER
A 106
- 6 / + 18
+ 10 / - 7
+ 12 / - 10
B 106
- 8 / + 22
+ 10 / - 7
+ 4 / - 3
C 106
- 7 / + 19
+ 8 / - 6
0
START
- 0 / + 18
+ 10 / -8
+ 15 / - 13
wing mix CG FLAPS
AILERONS
ELEVATOR
RUDDER
A ELEVATOR > FLAPS & AILERONS 106
A AILERONS > RUDDER 106
- 6 / + 18
- 10 / + 12
B ELEVATOR > FLAPS & AILERONS