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Old 12-25-2013, 06:09 AM   #1
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Default Will-Hobby Gee Bee R2 .90 - 1.20 power plant question.

Hello there all

I am hoping some input can be given here for this setup I am thinking of using. The plane specs are below. Will this setup fly this plane like a rocket? Or be just perfect? Any help would be appreciated.

It has a wingspan of 71" and a length of 47". You can power it with either a .91 two cycle or 1.20 four cycle engine. It has a fiberglass fuselage and balsa and ply built up wings. All up RTF weight is about 9 lbs. on glow or gas. As well the weight really did not change going electric 10s 1.60 size.

The setup I am thinking of using is a Rimfire or Turnigy 1.60 brushless. Using eCalc the setup with a Rimfire 1.60 250Kv brushless looks pretty good on 10s. The Turnigy G160 245Kv brushless is almost identical in results. using a 17x10 APC-E prop.

Remarks: ----------------------------------------------------
Battery
Load: 9.82 C
Voltage: 35.53 V
Rated Voltage: 37.00 V
Flight Time: 6.1 min
Mixed Flight Time: 10.4 min
Weight: 1400 g
49.4 oz

Motor @ Optimum Efficiency-------------------------------------------
Current: 49.67 A
Voltage: 35.34 V
Revolutions*: 8146 rpm
electric Power: 1755.1 W
mech. Power: 1646.8 W
Efficiency: 93.8 %


Motor @ Maximum------------------------------------------------------
Current: 49.10 A
Voltage: 35.36 V
Revolutions*: 8155 rpm
electric Power: 1735.8 W
mech. Power: 1628.7 W
Efficiency: 93.8 %
est. Temperature: 43 C
109 F


Propeller------------------------------------------------------------------
Static Thrust: 7716 g
272.2 oz
Revolutions*: 8155 rpm
Stall Thrust: 5010 g
176.7 oz
Pitch Speed: 124 km/h
77 mph
Tip Speed: 664 km/h
412 mph
specific Thrust: 4.44 g/W
0.16 oz/W


Total Drive------------------------------------------------------------------
Drive Weight: 2354 g
83 oz
All-up Weight: 4200 g
148 oz
Power-Weight: 433 W/kg
197 W/lb
Thrust-Weight: 1.84 : 1
P(in) @ max: 1816.6 W
P(out) @ max: 1628.7 W
Efficiency @ max: 89.7 %


This setup below is the Rimfire 1.20 size on 6s 6000 mah 20/30C, with a 100A ESC. 16x8 prop. Which would you run? I know the 1.20 setup is going to be cheaper battery and ESC etc. wise.

Battery----------------------------------------------------------------------
Load: 11.42 C
Voltage: 20.64 V
Rated Voltage: 22.20 V
Flight Time: 5.3 min
Mixed Flight Time: 8.9 min
Weight: 942 g
33.2 oz

Motor @ Optimum Efficiency---------------------------------------------
Current: 69.90 A
Voltage: 20.43 V
Revolutions*: 8732 rpm
electric Power: 1428.1 W
mech. Power: 1290.9 W
Efficiency: 90.4 %


Motor @ Maximum----------------------------------------------------------
Current: 68.50 A
Voltage: 20.47 V
Revolutions*: 8763 rpm
electric Power: 1401.9 W
mech. Power: 1267.2 W
Efficiency: 90.4 %
est. Temperature: 49 C
120 F


Propeller---------------------------------------------------------------------
Static Thrust: 6059 g
213.7 oz
Revolutions*: 8763 rpm
Stall Thrust: 4673 g
164.8 oz
Pitch Speed: 107 km/h
66 mph
Tip Speed: 671 km/h
417 mph
specific Thrust: 4.32 g/W
0.15 oz/W


Total Drive------------------------------------------------------------------
Drive Weight: 1619 g
57.1 oz
All-up Weight: 4200 g
148 oz
Power-Weight: 362 W/kg
164 W/lb
Thrust-Weight: 1.44 : 1
P(in) @ max: 1520.7 W
P(out) @ max: 1267.2 W
Efficiency @ max: 83.3 %


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