Mark M Posted September 19, 2011 Share Posted September 19, 2011 (edited) can someone confirm my theory if i had 2 exactly the same motors, powered off the same battery, but one reverse wired so it rotated the opposite direction, would they both turn at the same speed for arguments sake say a airfix 1/24 motor (although i havent got any yet) as you may have guessed im thinking of motorising my chinook, in my biggest plan ever, i can do the lights no probs but the rotors are a bit of a challenge Edited September 20, 2011 by markmarples Link to comment Share on other sites More sharing options...
SaintsPhil Posted September 19, 2011 Share Posted September 19, 2011 As they are the same DC motor they should indeed spin at the same speed, however given tolerances with the wiring in the motor you could never guarantee they would perform the same! Also directly connected they will spin pretty fast, you could put a resistor in series with either connection to limit the speed of the motor. By varying the resistance you could match the motor speeds. You could in fact use a variable resistor, this would allow you to adjust the speed to match. Drop me a PM if you want any more help! Phil Link to comment Share on other sites More sharing options...
Mark M Posted September 19, 2011 Author Share Posted September 19, 2011 As they are the same DC motor they should indeed spin at the same speed, however given tolerances with the wiring in the motor you could never guarantee they would perform the same!Also directly connected they will spin pretty fast, you could put a resistor in series with either connection to limit the speed of the motor. By varying the resistance you could match the motor speeds. You could in fact use a variable resistor, this would allow you to adjust the speed to match. Drop me a PM if you want any more help! Phil thanks phil, yep id already figured on the resistor otherwise id take off, my worry is the rotors conflicting, given that these are plastic and there is a clearance i don think they will interact like the real thing but i dont know, and id want them fairly slow so id guess there still may be droop can of worms fully open! phil if i used 1 variable resistor in parralell with the 2 motors in therory would they be the same speed Link to comment Share on other sites More sharing options...
pigsty Posted September 19, 2011 Share Posted September 19, 2011 (edited) If you put the resistor in parallel with the motors you won't get the effect you want. You need to wire it in series. The simplest place to put it is between the battery and the point where the wires to the two motors diverge. As for blades clashing, that's a risk, but it depends partly on whether the kit's blades are straight or bowed and partly on how sturdy the axle is on which they'll be rotating. On the real thing the blades are flexed a long way up as they turn and the biggest clashing risk is in a turn, when one side of the disc is pitched further to change the distribution of lift. With the kit blades none of that is likely (unless you plan some serious engineering) and my guess is that if you have straight blades, you should have few problems. Edited September 19, 2011 by pigsty Link to comment Share on other sites More sharing options...
Mark M Posted September 19, 2011 Author Share Posted September 19, 2011 thanks pigsty, i wont be doing a major engeniering job, bur as long as you can see the contrarotation and they arent too fast or collide im happy Link to comment Share on other sites More sharing options...
Mark M Posted September 20, 2011 Author Share Posted September 20, 2011 ok chaps do i need a 10k or 100k variable resistor to regulate the speed of my motors i have no idea Link to comment Share on other sites More sharing options...
Radleigh Posted September 20, 2011 Share Posted September 20, 2011 As much as I would love to see it, I really think your going to have problems of the blades clashing. Good luck! Link to comment Share on other sites More sharing options...
pigsty Posted September 20, 2011 Share Posted September 20, 2011 ok chaps do i need a 10k or 100k variable resistor to regulate the speed of my motors i have no idea Depends on the voltage of the batteries, the normal speed of the motor with that voltage, and the speed you want the rotors to turn at. Link to comment Share on other sites More sharing options...
Mark M Posted September 20, 2011 Author Share Posted September 20, 2011 ok it will be a 9v bettery Link to comment Share on other sites More sharing options...
SaintsPhil Posted September 20, 2011 Share Posted September 20, 2011 As it's a DC motor it's actually the current that's the important factor (as long as you don't exceed the maximum the motor can take). What the resistor does is limit the flow of current to reduce the speed of the motor, by reducing field strength in the windings. In fact as the energy in the battery depletes the terminal voltage will drop, as the battery is a constant current source. Sorry bit of electronics 101 to start! I would suggest the 100K as in fact they go from 0ohms up to the max so with the 100K you get a greater range. The motor will have a minimum current you need to put into it get get it started, this will be quite low I would think as the blade assembly should be light. You might want to start with the resistor at it's max and slowly reduce until the blades start turning. The only thing you need to bear in mind is that, as I said above, you may need to tweak the resistor as the battery discharges, so leave it accessible. Hope that helps! Drop me a PM if you get stuck. Link to comment Share on other sites More sharing options...
Mark M Posted September 20, 2011 Author Share Posted September 20, 2011 As it's a DC motor it's actually the current that's the important factor (as long as you don't exceed the maximum the motor can take). What the resistor does is limit the flow of current to reduce the speed of the motor, by reducing field strength in the windings. In fact as the energy in the battery depletes the terminal voltage will drop, as the battery is a constant current source.Sorry bit of electronics 101 to start! I would suggest the 100K as in fact they go from 0ohms up to the max so with the 100K you get a greater range. The motor will have a minimum current you need to put into it get get it started, this will be quite low I would think as the blade assembly should be light. You might want to start with the resistor at it's max and slowly reduce until the blades start turning. The only thing you need to bear in mind is that, as I said above, you may need to tweak the resistor as the battery discharges, so leave it accessible. Hope that helps! Drop me a PM if you get stuck. phil thats fab again i owe you - ordered from ebay As much as I would love to see it, I really think your going to have problems of the blades clashing. Good luck! defeatest, but i think you may be right Link to comment Share on other sites More sharing options...
SaintsPhil Posted September 20, 2011 Share Posted September 20, 2011 No worries, glad to help! Look forward to seeing it!! Phil Link to comment Share on other sites More sharing options...
Anthony Kesterton Posted October 30, 2011 Share Posted October 30, 2011 Hi Mark This sounds like a really neat idea - did you try it? Blade clashes or takeoff? anthony Link to comment Share on other sites More sharing options...
Mark M Posted October 30, 2011 Author Share Posted October 30, 2011 Hi MarkThis sounds like a really neat idea - did you try it? Blade clashes or takeoff? anthony yep ive done it im still working on the project if ive done this right click on the video Link to comment Share on other sites More sharing options...
Anthony Kesterton Posted November 6, 2011 Share Posted November 6, 2011 Video works. Missed your reply so only just seen the video. Looks very impressive - are the blades catching at all? anthony Link to comment Share on other sites More sharing options...
Mark M Posted November 6, 2011 Author Share Posted November 6, 2011 they did at first until i fixed the motors in place now they spin really well, its been on hold for a while until i got some steel rod for the stand but will be back on the bench soon Link to comment Share on other sites More sharing options...
Sup3rFly88 Posted December 30, 2011 Share Posted December 30, 2011 I have to to say that is amazing! I am just starting to actually finish models after 3 years of failing. This project is gonna spur me on as I know there is so much more to this hobby. Ian End of Line Link to comment Share on other sites More sharing options...
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