RE: New Piedmont Focus 90/110
OK, I made an an assumption about the wing area of 1100 sq.in. This will get Motocalc in the ballpark, which is all you can ever do with Motocalc.
Here is the first set of numbers. This system happens to be the same I use in my Dream 110. It works very well.
Focus Sport
850ft above Sea Level, 29.92inHg, 56°F
Motor: Hacker C50 10XL; 1624rpm/V; 1.26A no-load; 0.0118 Ohms.
Battery: Thunder Power TP2100 (ProLite) (15C); 8 series x 3 parallel cells; 2100mAh @ 3.7V; 0.018 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: APC 18x12 Electric; 18x12 (Pconst=1.31; Tconst=1) geared 6.7:1 (Eff=92%).
Airframe: Focus Sport; 1100sq.in; 149oz RTF; 19.5oz/sq.ft; Cd=0.043; Cl=0.06; Clopt=0.42; Clmax=0.81.
Stats: 184 W/lb in; 161 W/lb out; 25mph stall; 35mph opt @ 56% (55:03); 94mph level; 3892ft/min @ 90°; -503ft/min @ -9.3°.
Warning:
• MotoCalc was unable to determine a throttle setting for hands-off cruise airspeed, so the best lift-to-drag ratio airspeed and throttle setting will be used instead.
• Inability to determine a throttle setting for an airspeed usually means the model is not capable of reaching the required speed with the given power system, or the airfoil information has not been specified correctly.
Power System Notes:
• The full-throttle motor current at the best lift-to-drag ratio airspeed (62.8A) falls approximately between the motor's maximum efficiency current (53.2A) and its current at theoretical maximum output (1124.5A), thus making effective use of the motor.
• The voltage (26.4V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.
Aerodynamic Notes:
• The static pitch speed (70.7mph) is within the range of approximately 2.5 to 3 times the model's stall speed (25.4mph), which is considered ideal for good performance.
• With a wing loading of 19.5oz/sq.ft, a model of this size will have trainer-like flying characteristics. It would make an ideal trainer, for use in calm to light wind conditions.
• The static thrust (255.2oz) to weight (149oz) ratio is 1.71:1, which will result in extremely short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and vertical climb-outs. This model will probably be able to perform a hover or torque roll.
• At the best lift-to-drag ratio airspeed, the excess-thrust (168.3oz) to weight (149oz) ratio is 1.13:1, which will give very steep climbs and incredible acceleration. This model can easily do consecutive loops, and has sufficient in-flight thrust for any aerobatic maneuver.
General Notes:
• This analysis is based on calculations that do NOT take motor heating effects into account. This also means that no calculations were done to determine if the motor might overheat.
• These calculations are based on mathematical models that may not account for all limitations of the components used. Always consult the power system component manufacturers to ensure that no limits (current, rpm, etc.) are being exceeded.