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Post by tronicgr on Jan 4, 2017 16:37:59 GMT
The last file I attached should be OK, I added final RPM and platform load capacity in Lbs.
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johann
Junior Member
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Post by johann on Jan 4, 2017 16:51:07 GMT
ok, thanks Johann
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David
New Member
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Post by David on Jan 4, 2017 17:19:29 GMT
johann that's cool where have you been picking up most the cockpit parts from like rudder pedals,yoke,gauges,etc. I'm going to read through blog now too.
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johann
Junior Member
Posts: 57
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Post by johann on Jan 5, 2017 11:15:55 GMT
Hi David, for my "cessna cockpit" I used the following parts: There is a VGA monitor 10.1" and 3 24" acer monitors. The acer monitor signal is from a matrox triple head box. To fill a gap between the steering wheel and the throttle control box I used a simple cup holder. All the rest is from saitek (more or less expencive), see picture. Johann
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johann
Junior Member
Posts: 57
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Post by johann on Jan 5, 2017 11:40:44 GMT
Hi Thanos, as I promised, here is the reworked excel list. Now we can calculate 2 types of motors, see picture. I reordered the columns and marked the key in fields for each kind of motor. I also described all the constant values to calculate all the important information’s. Inside the sheet you can check 3 motors and both types. Of course you should only use one of them. Please do a short check if all is right. I tested it and for me it’s ok so. I hope we can now really reduce the torque discussion. It is possible to create a Thread named “Tools” and put the list to it. It would be easier to find. What do you think about it? In my case now I would prefer the M3 motor (last line) and use for it the WJ200-007SF VFD inverter. Thanks again for your help. Johann AC_Motor_torque_speed_calculation.xlsx (117.83 KB)
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Post by hexpod on Jan 5, 2017 12:33:57 GMT
Hi Thanos, as I promised, here is the reworked excel list. Now we can calculate 2 types of motors, see picture. I reordered the columns and marked the key in fields for each kind of motor. I also described all the constant values to calculate all the important information’s. Inside the sheet you can check 3 motors and both types. Of course you should only use one of them. Please do a short check if all is right. I tested it and for me it’s ok so. I hope we can now really reduce the torque discussion. It is possible to create a Thread named “Tools” and put the list to it. It would be easier to find. What do you think about it? In my case now I would prefer the M3 motor (last line) and use for it the WJ200-007SF VFD inverter. Thanks again for your help. Johann View AttachmentView AttachmentThis is cool but... First of all I don't understand why you use the velocity factor for the dynamic calculation of the torque. It should be acceleration. Am I wrong? Second, you should incorporate the platform ratio factor. Smaller the platform bigger the torque requirements. Cheers
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johann
Junior Member
Posts: 57
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Post by johann on Jan 5, 2017 12:49:03 GMT
Hi hexpod,
the list is from Thanos. I adapt only the given parameter from the worm gear motor I'm looking for. If there is something missing or even wrong (I did not believe) please feel free to change things inside. I guess we’ll get Thanos comments soon.
Regards Johann
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Post by tronicgr on Jan 5, 2017 17:27:20 GMT
The calculations are correct. Here is a page that explains them: www.elec-toolbox.com/Formulas/Motor/mtrform.htmThe AC motors behave different from DC motors and are act more as a kind of stepper motors where the faster you move the less torque you get from them. Said that, you can get more torque from slowing down the max speed of ac motors but you will have to spend more power too as the resistance of the coils increase (stall currents). Also i don't use this to calculate the exact load as this varies because of the other mechanical aspects, but it will provide a very close approximate estimate to size the motors and gearboxes needed. Thanks Thanos
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johann
Junior Member
Posts: 57
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Post by johann on Jan 5, 2017 18:14:20 GMT
Hi Thanos,
thanks for the explanation. I'm glad that everything is ok with the new excel list. So anyone can use it now for AC motors to calculate torque and or motors. For you I've ordered now 6 times WJ200-007SF inverters. Next week I'll look for the best motor and order it as well.
Thanks Johann
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Post by hexpod on Jan 5, 2017 20:13:17 GMT
The calculations are correct. Here is a page that explains them: www.elec-toolbox.com/Formulas/Motor/mtrform.htmThe AC motors behave different from DC motors and are act more as a kind of stepper motors where the faster you move the less torque you get from them. Said that, you can get more torque from slowing down the max speed of ac motors but you will have to spend more power too as the resistance of the coils increase (stall currents). Also i don't use this to calculate the exact load as this varies because of the other mechanical aspects, but it will provide a very close approximate estimate to size the motors and gearboxes needed. Thanks Thanos Thank you for the explanation.
in the result, 282 kg is with safety factor already applied?? (423/1.5=282)
or it has to be done? (282/1.5=188kg)
cheers
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Post by tronicgr on Jan 5, 2017 20:23:36 GMT
Are you trying to apply these calculations for the Clearpath motors? Check if the torque you get is consistent with the torque mentioned in the Clearpath motors datasheet! Not sure what you mean with the safety factor? What is this?
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Post by hexpod on Jan 5, 2017 20:30:46 GMT
Thank you for the explanation.
in the result, 282 kg is with safety factor already applied?? (423/1.5=282)
or it has to be done? (282/1.5=188kg)
cheers
Are you trying to apply thelse calculations for the Clearpath motors? Check if the torque you get is consistent with the torque mentioned in the Clearpath motors datasheet! Not sure what you mean with the safety factor? What is this? in the excel I can read: constant payload safety factor 1.5 what is this?
Please precise.
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Post by hexpod on Jan 5, 2017 20:59:24 GMT
My empirical torque test was done with Clearpath limited to 4.4Nm/800rpm. That is 0.5 horse power. isn't it?
In my empirical test with 180 kg, you can notice that with high acceleration, the motors are almost clipping while with the same values excel is giving 272kg as load capacity.
vimeo.com/189066160
You have basically to divide the excel value by 1.5 to obtain the real payload
272/1.5 = 181
that's one-third load capacity less!
cheers
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Post by tronicgr on Jan 5, 2017 22:14:30 GMT
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Post by tronicgr on Jan 5, 2017 22:18:03 GMT
Hi Thanos, as I promised, here is the reworked excel list. Now we can calculate 2 types of motors, see picture. I reordered the columns and marked the key in fields for each kind of motor. I also described all the constant values to calculate all the important information’s. Inside the sheet you can check 3 motors and both types. Of course you should only use one of them. Please do a short check if all is right. I tested it and for me it’s ok so. I hope we can now really reduce the torque discussion. It is possible to create a Thread named “Tools” and put the list to it. It would be easier to find. What do you think about it? In my case now I would prefer the M3 motor (last line) and use for it the WJ200-007SF VFD inverter. Thanks again for your help. Johann Hi Johann, I found an error in your calculations, you calculate the gearbox efficiency, while you need to get the value manually from the gearbox datasheet...!! Thanks Thanos
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