MotOpinion - Sig LT-25 Twin

MotOpinion - Sig LT-25 Twin
1000ft above Sea Level, 68°F

Motor:	Kyosho Atomic Force 17T; 3531rpm/V; 0.035 Ohms; 2.94A idle.
Battery:	Sanyo RC2000; 14 cells; 2000mAh @ 1.2V; 0.0035 Ohms/cell.
Speed Control:	Stefan's 4-FET ESC with BEC and Brake; 0.0025 Ohms; High rate.
Drive System:	Master Airscrew 3.0:1 Gearbox w/APC Prop; 2 motors (series); 10x7 (Pconst=1.11; Tconst=0.95) geared 3:1.
Airframe:	Sig LT-25; 724sq.in; 104.7oz; 20.8oz/sq.ft; Cd=0.063; Cl=0.52; Clopt=0.69; Clmax=1.2.
Filter:	30A max, 48A max (ESC), 51 to 64mph, 240sec min.
Stats:	58 W/lb in; 44 W/lb out; 22mph stall; 29mph opt @ 67% (16:40); 33mph level @ 74% (13:58); 623ft/min @ 14.2°; -288ft/min @ -6.5°.

The full-throttle motor current at the best lift-to-drag ratio airspeed (23.5A) falls between the motor's maximum efficiency current (23.3A) and its current at maximum output (93.8A), thus making effective use of the motor.
The voltage (15.6V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.

The static pitch speed (53mph) is within the range of approximately 2.5 to 3 times the model's stall speed (22mph), which is considered ideal for good performance.
With a wing loading of 20.8oz/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 (52.7oz) to weight (104.7oz) ratio is 0.5:1, which will result in short take-off runs, and no difficulty taking off from grass surfaces (assuming sufficiently large wheels).
At the best lift-to-drag ratio airspeed, the excess-thrust (27.4oz) to weight (104.7oz) ratio is 0.26:1, which will give strong climbs and rapid acceleration. This model will most likely readily loop from level flight, and have sufficient in-flight thrust for many aerobatic maneuvers.

This analysis is based on calculations that take motor heating effects into account.

Generated by MotoCalc 6.05, 2002-04-01 21:01.