Using "Motocalc"
10-09-2002, 12:35 AM
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Using "Motocalc"
Are any of you guys running your prop/battery/motor specs thru "motocalc". I've been running many different scenarios thru Motocalc and I've been surprised at the results. In many of the scenarios, the results show that Nimh batteries will overheat with a given prop size.
In the final analysis, if Motocalc is accurate, choices of the correct prop and/or battery with a given motor and gearbox are limited, unless you are willing to give up battery life, performance or both.
Comments ?
In the final analysis, if Motocalc is accurate, choices of the correct prop and/or battery with a given motor and gearbox are limited, unless you are willing to give up battery life, performance or both.
Comments ?
10-09-2002, 07:13 AM
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Using "Motocalc"
I use Motocalc quite a bit and find it fairly accurate....but I always leave the heating option switched off. When I've tried with it on it seemed to underestimate performance and tell me everything was getting too hot.
But it is easy to ruin some NiMH cells by trying to drag too much current out of them, I just don't think Motocalc can tell you very much about it.
Steve
But it is easy to ruin some NiMH cells by trying to drag too much current out of them, I just don't think Motocalc can tell you very much about it.
Steve
10-09-2002, 06:16 PM
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Using "Motocalc"
If you choose your NiMH batteries by physical size, and not by mAh capacity, heating is almost never a problem.
Say you're flying a Zagi 400. The stock battery pack is an 8-cell "2/3A" NiCd pack with 500mAh capacity. To properly replace it with a NiMH battery, you need to find 2/3A NiMH cells, not a NiMH battery with 500mAh of capacity.
Say you're flying a Zagi 400. The stock battery pack is an 8-cell "2/3A" NiCd pack with 500mAh capacity. To properly replace it with a NiMH battery, you need to find 2/3A NiMH cells, not a NiMH battery with 500mAh of capacity.
10-23-2002, 12:55 PM
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thanks so much
I am a little confused what is time is it run time.temp is it motor
or batt.Pspd is this like max air speed.
and could you run it one more time with 3.5 to 1
I am a little confused what is time is it run time.temp is it motor
or batt.Pspd is this like max air speed.
and could you run it one more time with 3.5 to 1
10-23-2002, 03:07 PM
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Using "Motocalc"
It doesn't. Pspd, or pitch speed, is the theoretical maximum speed the airplane can fly at, assuming zero drag and perfect conditions, i.e. the propeller is screwing through the air like a bolt through a nut, dragging the plane behind it...
The drag of the airplane is what determines the in-flight airspeed.
Of course it is possible for an airplane to exceed the propeller's pitch speed, because the prop blades are actually airfoils, and create lift. If the lift force generated by the prop exceeds drag, the airplane will accelerate. The faster the airplane goes, the more drag is generated airframe, and the less lift is generated by the prop. Eventually you reach equilibrium, where the plane is going flat out at its maximum speed.
The drag of the airplane is what determines the in-flight airspeed.
Of course it is possible for an airplane to exceed the propeller's pitch speed, because the prop blades are actually airfoils, and create lift. If the lift force generated by the prop exceeds drag, the airplane will accelerate. The faster the airplane goes, the more drag is generated airframe, and the less lift is generated by the prop. Eventually you reach equilibrium, where the plane is going flat out at its maximum speed.
10-26-2002, 04:40 AM
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Using "Motocalc"
Motor: Graupner Speed 400 7.2V #1794; 2227rpm/V; 0.357 Ohms; 0.72A idle.
Battery: Sanyo 500AR; 10 cells; 500mAh @ 1.2V; 0.009 Ohms/cell.
Speed Control: Generic High Rate ESC; 0.003 Ohms; High rate.
Drive System: Graupner Speed 400 2.33:1 Gearbox; 7x3 (Pconst=1.31; Tconst=0.95) geared 2.33:1.
Airframe: mustang 400; 231sq.in; 30oz; 18.7oz/sq.ft; Cd=0.053; Cl=0.47; Clopt=0.72; Clmax=1.24.
Filter: 15A max.
Stats: 24 W/lb in; 17 W/lb out; 20mph stall; 26mph opt @ 101% (7:37); 33mph level @ 101% (7:37); -224ft/min @ -5.5°; -224ft/min @ -5.5°.
Seems a useful tool in calculations of motor-prop-battery-etc. I have to spend some time to find out how varying changes will effect flight times and prevent stalling. Nice tool Software..I just wish it was updated more on ESC's than using Generics.
Battery: Sanyo 500AR; 10 cells; 500mAh @ 1.2V; 0.009 Ohms/cell.
Speed Control: Generic High Rate ESC; 0.003 Ohms; High rate.
Drive System: Graupner Speed 400 2.33:1 Gearbox; 7x3 (Pconst=1.31; Tconst=0.95) geared 2.33:1.
Airframe: mustang 400; 231sq.in; 30oz; 18.7oz/sq.ft; Cd=0.053; Cl=0.47; Clopt=0.72; Clmax=1.24.
Filter: 15A max.
Stats: 24 W/lb in; 17 W/lb out; 20mph stall; 26mph opt @ 101% (7:37); 33mph level @ 101% (7:37); -224ft/min @ -5.5°; -224ft/min @ -5.5°.
Seems a useful tool in calculations of motor-prop-battery-etc. I have to spend some time to find out how varying changes will effect flight times and prevent stalling. Nice tool Software..I just wish it was updated more on ESC's than using Generics.
