Čez zimo sem naredil Fokker DVII, za katerega se je izkazalo, da je precej težji, kot sem na začetku predvideval.
Specifikacije modela:
Razpon zgornjega krila (s krivuljami eleronov): 1115mm
Razpon zgornjega krila (brez krivulj eleronov): 1052mm
Razpon spodnjega krila: 870mm
Dolžina trupa: 848mm + propeler.
Teža modela: 1765g (letalna teža z baterijo in 35-36 motorjem)
Vprašanje pa je sledeče:
Kakšen motor izbrati, da bo zadeva letela v redu?
Vgrajen imam 35-36 1450KV motor na 3S bateriji 2450mAh/30C skupaj s 40A ESC in 9x6 priporočenim propelerjem za ta motor.
Nekaj kolegov na forumu je predlagalo 35-42 ali celo 35-48 motor.
Ali menite, da bi z obstoječim 35-36 motorjem model letel solidno ali bolj padal kot kamen?
Na nekaj forumih sem zasledil , da je 100W na funt (0.453kg) več kot dovolj za "scale flight", zaradi česar sem pri modelu s 4 funti teže tudi vgradil 400W motor.
The full-throttle motor current at the best lift-to-drag ratio airspeed (30,8A) falls approximately between the motor's maximum efficiency current (30,3A) and its current at theoretical maximum output (165,5A), thus making effective use of the motor.
Possible Aerodynamic Problems:
The hands-off level flight speed (28mph) is lower than the best lift-to-drag ratio level flight speed (28mph). In most situations, the opposite is desirable.
Hands off level flight speed can be increased by reducing the airfoil camber or angle of attack.
Aerodynamic Notes:
The static pitch speed (53mph) is within the range of approximately 2,5 to 3 times the model's stall speed (18mph), which is considered ideal for good performance.
Due to some of the potential problems listed above, this model may require an experienced pilot.
The static thrust (42,4oz) to weight (77,7oz) ratio is 0,55:1, 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 (15,5oz) to weight (77,7oz) ratio is 0,2:1, which will give good climbs and acceleration. This is a good in-flight thrust to weight ratio for a basic trainer.
Pri motorju Ray 35-42, 1250KV in TURNIGY Sentry 40amp:
The full-throttle motor current at the best lift-to-drag ratio airspeed (30,9A) falls approximately between the motor's maximum efficiency current (24,8A) and its current at theoretical maximum output (155,4A), thus making effective use of the motor.
Possible Aerodynamic Problems:
The hands-off level flight speed (28mph) is lower than the best lift-to-drag ratio level flight speed (29mph). In most situations, the opposite is desirable.
Hands off level flight speed can be increased by reducing the airfoil camber or angle of attack.
Aerodynamic Notes:
The static pitch speed (50mph) is within the range of approximately 2,5 to 3 times the model's stall speed (19mph), which is considered ideal for good performance.
Due to some of the potential problems listed above, this model may require an experienced pilot.
The static thrust (49,9oz) to weight (78,7oz) ratio is 0,63:1, 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 (18,7oz) to weight (78,7oz) ratio is 0,24:1, which will give good climbs and acceleration. This is a good in-flight thrust to weight ratio for a basic trainer.
Naročil sem Ray 35-42 motor pri 1250KV, ki naj bi pri 4S in 40A razvil 540W. ESC, ki ga imam menda brez težav zdrži tudi burste do 58A, kar bi moralo bit dovolj v redu, da se bosta lepo gledala motor in kontroler.
Čeprav kot izgleda, bi tudi 35-36 moral bit dovolj....
Poskusil bom torej s 35-42, morda kasneje tudi s 35-36.
Edino tega pa še ne vem, kaj naj zdaj s propelerjem....tistega, ki ga priporočajo pri proizvajalcu motorja ali tistega, ki ga je MotoCalc priporočil?
