In 10 years of tinkering around with RC, being a novice, not an expert… This was by far the best video I’ve ever seen for tying together all these values, and how it relates to overall set up well done thank you
A little late in responding to this vid but I'v looked far and wide for information this easy to understand and helpful in my RC design efforts and nothing compares. Thanks for taking the time and for helping those of us that sometimes forget what all the numbers represent and how they can affect our planes performance and safety.
I am sending this video to all new flyers and the clubs I belong to. It really is the best explanation of the different parts of an electric RC system that I have seen.
Very good for us old people that still have glow plug engines. These engines are slowly wearing out. Now I want to change to electric. I learned that there is no chart that gives me a .60 glow engine replacement is a “xxxx” electric motor with the same prop. So you helped me get a ideal for a good direction where to start. Thank you
Thank you so much for making this! I have searched for months to find a simple way to design a power system that fits my different conversions from glow to electric without spending a fortune, or buying the wrong components. This gives you all the information needed to get in the ballpark in one easy location. I screenshotted the slides to share with the members of our club who may need advice in this area. Armed with this info and the understanding of KV in brushless outrunners from other videos, one can make informed choices in selecting a power system that meets their needs!
Wow! Thank you so much for this reference. A great video to come back to in my project to take an old balsa .60 nitro and update it to a Pixhawk controlled EP. I'm in over my head a bit, but that's how I like it. Always learning
Awesome video explaining this stuff from a REAL engineering perspective. I'm new to this stuff and this video explained just about everything I need to know about the general power system. This has been a rare video that explains everything with this much detail. Thank you.
Nice video for newbies like myself! I am attempting to scratch build my first plane using corrugated cardboard. Already purchased my Flysky FS-i6X 10 ch radio, was just trying to figure out the lipo battery, esc, motor, and of course, lipo battery charger. Thanks.
First class video. I'm new to RC plane flying, started with a ready to fly training model which was great. Progression has now taken me to ARF models where the installation of motor, esc and battery is required. The most difficult part of this process for me has been "what size motor" to fit to the plane, especially when some manufacturers only recommend engine sizes. I found that the online conversion charts, (engine to motor) were confusing and some differed. This video stating 130W / Ib has made this much easier. The whole video has giving me a greater understanding of RC plane electric set up. Thank you. I purchased a model from a RC club member, Thunder tiger Cessna Cardinal 177. This model is a few years old but was still in box, unmade. The model was intended for glow engines, but I will convert it for electric power. Another club member has the same model and stated to me that it would be very difficult to convert to electric due to the weight of the model. I will soon have an idea of the weight of the model and then look at motor sizing. Thank you once again.
I seriously doubt weight will stop the plane from flying on electric power. People who say things like that really don't have an appreciation for what can be accomplished with modern brushless motors and strong lipo batteries these days. In any case, I'm glad you found this video helpful. I'm surprised it doesn't have a LOT more views given the number of new people who need help with this subject and the great deal of misinformation out there even amongst experienced pilots. Best of luck as you begin your RC journey.
awesome video i learned a lot it was easy to follow along and im going to be using this alot since i build alot of foam board planes bravo keep em coming
Sunnysky motors are my first choice these days. Cobra and Bad Ass motors from Innov8tive designs and rcdude are my 2nd option. Finally Leopard motors from Altitude hobbies are my 3rd choice.
Great video! I might have missed it… how would you go about trying to calculate/guess run time before the battery is at the 20% or so when you want to stop using it? I think I understand starting with Wattage needed, then plugging in your battery of choice to factor your Voltage (3.7 for 1S, 7.4 for 2S), so you can then determine Amps needed. Then you want to make sure your ESC slightly exceeds that Amp requirement. Then divide ESC Amp rating by battery Amp rating to determine minimum C factor needed for battery. But how do you figure how long your selected battery will last? For example, on a little 8 oz plane: 50W power required, using a single 1S 800mAh 30C battery gets you 3.7 Volts at 13.5 Amps required. Bump ESC up to 20 Amp, divide by .8 and you get a minimum 25C battery factor. This means technically the single 1S 800mAh 30C battery should work, but seems like it would barely work given the minimum 25C requirement.
For those who care about flight time or efficency you can also use a power tester and see the amps drawn for different props, once you have amps you can do some simple maths and get flight time. 5amphour battery for example can deliver 5 amps for 60min or 10amps for 30min 20amps for 15mins 40amps for 7.5mins ect. can be usefull for choosing battery that fits your flying style also.
Very useful video! The only thing I recommend is when 2 packs are wired parallel or in series, the voltage of the packs needs to be the same. Only use matching packs in capacity and voltage when you wire them together in series or parallel.
They don't need to be the same in series. In parallel, yes. In series, no. In series they need to be the same capacity. In parallel they need to have the same voltage.
Bummer, you're making my hobby just like my homework was 50 years ago. Didn't do then. But, thanks for explaining it so well. Really makes sense. Answers some questions that I had.PS. That chart at the end is worth printing. Can you post a pdf of it?
Thank you for your video. It's a great help to me. I'm struggling with the process of finding the right motor. When i go to sites to search for motors, it seems there are no tables summarizing all of their motors. Instead i have to open up the details of each one to get the details. And some use kv instead of total watts which i dont understand how to convert/translate. I also dont understand what the significance of the diameter of the motor is other than physically fitting in my model and probably torque is a factor too. If it has to be jigsaw puzzle examining every piece so be it, but maybe im missing something. Sites I've browsed put the kv on the main title of the product and you have to dig for the wattage. Which makes me think kv is an indicator people can recognize on sight.
Excellent tutorial. Thanks for putting it together and making it available! I have a question about the last topic you touched on, i.e., wiring batteries in series or in parallel. So what happens to the C rating in either configuration? If for series connection the amperage and capacities stay the same does that implay that the C rating remains as well? Or is it that the 2 batteries in series now allow twice the discharge rate?
Rwy'n iawn, diolch. Hoffwn pe bawn i'n rhugl mewn ieithoedd eraill, ond rwy'n defnyddio technoleg i'm helpu i gyfathrebu â phawb sy'n estyn allan ar fy sianel. Gwerthfawrogi eich sylwadau. Gobeithio eich gweld chi o gwmpas.
Very excellent video, thank you! I do have a question about the example you used regarding volts and/or amps: is the voltage and/or amps at full throttle? If so, the voltage notably drops at higher throttle settings. Not sure what the conditions are when speaking of the wattage. If you could please advise it would be greatly appreciated.
Throttle and sag are not part of the equation. Volts * Amps is always Watts. Don't cross mechanical variation with the mathematical law. If under a certain load, the mechanical apparatus (battery) sags in providing the motive force of current demanded by the load, that is a mechanical deviation, not a deviation of the formula. Volts * Amps = Watts at any throttle position or battery state.
Thank you for the quick response. So in your example 975w /20volts = 48.75a, the 20 volts is the nominal battery voltage not taking into account sag correct?
20 volts is just 20 volts. If the power source is charged to peak (4.2v/c) and it's a 5s battery, the voltage is 21 volts. If under load the battery delvers 20 volts, it's just 20 volts which means it sagged 1 volt. But the math still stands--the wattage input will be 20*current.
Good video! HOWEVER, you are overestimating the power loading figures a bit IMHO, which may throw off a beginner. In an article published 1987, Keith Shaw showed that his Spitfire with aerobatic performance needed only 50W/lbs. For good aerobatic performance from the Spitfire, he suggested increasing the power loading to 60+W/lbs. He quotes the power to take off from ground to be 30-50W/lbs, sport aerobatics to be 40-60W/lbs, fast aerobatics with some 3D to be 70-100W/lbs. This is documented data, and I have no reason to dispute it. Also, he experimented with these power loading figures when we were using brushed gear motors, Co motors with NiCd batteries. Things are better now, and I have no idea why Eflite quotes these power loading figures which almost double what he has found. Pat Trittle, another electric RC aircraft designer, quoted slightly higher numbers: park flyers, trainers need 35-50W/lbs, planes with mild aerobatic performance 70-80W/lbs, all-out acrobats 100-125W/lbs, 3D performers 175+W/lbs. Eflite data you are showing match only for advanced aerobatic airplanes, but NOT for park flyers, slow scale models and trainers. After dealing with the results from Ecalc and Motorcalc, they also agree with Trittle, and show "slightly" higher power loading numbers than what Keith Shaw obtained. The reason I am elaborating the power loading is because it is the most essential design element besides wing loading to select an appropriate motor and fly the aircraft properly.
Tried to help guys at my club understand some ideas about their receiver packs Nimh, NiCads, etc. that a voltage meter check is good but predicts little about the remaining amps in the battery. Better to measure amps used/flight x #number of flights and note if you are refilling what you used. It was like talking to a wall.
Extremely helpful and I appreciate the examples used. I will use this approach in designing my power systems for some foam board planes that I am building. Several years ago, I obtained the Dynam Hawk Sky (v1) and failed to get this to fly due to an underpower engine (or so I think). It has sat in my workshop for several years now, but am starting to rekindle my interest in RC. Your video has helped with some fundamental understanding of Watts, Amps, ESC, Props, and Batteries. Hopefully, this will lead to better success!
Hey John, so I watched this video as you suggested and I also watched your Spitfire Power test with the Cobra 610KV motor. I ordered the Cobra 610KV motor, a 13X8X3 prop, a 3 blade Spinner, and two 4000 mah 30C 5S batteries. So the same power system you have for your Spitfire. One difference is that you used a 100A ESC and I'm planning on using the Skywalker 80A ESC. According to what you say here, I should go for 10% higher ESC rating than my PEAK Amp draw. On your Cobra 610KV Motor test you pulled about 60 amps and 1111 Watts. So here is my Math: My plane will weigh 6.4 pounds, 1111 Watts / 6.4 = 173.59 watts per pound, I think that will work. ESC needed is a minimum of 66 Amps, I'm using an 80 Amp ESC so that should be good, and the battery discharge capability is 30C x 4 amps = 120 Amps, so that should be good too. Thanks for all your help and guidance with my Power setup. This video is a huge help.
I think you're going to like that arrangement quite a bit. You'll be fine with that ESC. I think I used the 100a because I had it. You won't be beating your batteries to death with that setup either.
@@RCVideoReviews I have a question. Has your opinion on Watts per Pound needed changed from the E-Flite guideline in this video? The guideline shows 110 - 130 watts per pound is what to shoot for with a Aerobatic High Speed model. I don't agree with that range. My Sport is about 4.75 pounds and I have a power system that is 800 Watts,. That's 168 watts per pound. I love how my Sport flies and it's NOT Unlimited Performance 3D. I don't think I would like it at all if I had a 600 Watt or 126 watts per pound, power system. I think that if I had it set up for the smaller power system, I'd have to fly it FULL THROTTLE 100% of the time just to keep it in the air and I'd burn down my battery quick. So has your opinion Changed on this Guideline?
Very good question. In the video, I explicitly state it's a "good guideline to start zeroing in on where *you* need to be. For my personal flying style, I like 175w+/lb. I feel very comfortable at that power level. I agree with you on the sport flying at that ratio (168) and it absolutely is not unlimited 3d. The point in all of this is to use it as a starting point and tune for your tastes. You could re-write your own chart and raise each description up one tier.
@@RCVideoReviews Understood. I don't think I'll rewrite their chart but, like you, I think I prefer about 170 per pound or higher. That extra power could come in handy in some situations and I think the battery life would be better. Thanks again for pointing out the Big Mistake I was about to make on my power setup. It might have flown but I would probably have had a terrible flying experience. For now on I'll do MY OWN calculations and not just accept what Tower recommends. You taught me a good lesson on that. Since I'm only 2 years into the hobby, I'm still learning and you and your channel are helping me Big Time!
what voltage per LiPo battery do you generally use for these calculations, the lower storage voltage or all cells at full charge voltage ?...thanks 3S_________4s____________5s____________6S_______________
1 C means 1 coulomb of charge ...now charge is stored in the battery, and 1C = 1amp.s (q=it) ..If it's written as 40C means you multiply given amp rating with C rating .
Can you post a video explaining this? How a 2s lipo with a total rating or voltage of 7.4 volts, which is made up of 2 cells rated at 3.7 volts per cell is best stored at 3.8 volts per cell or rather 7.6 volts total. Why is this the best storage voltage that it should be "discharged down" to? How far passed the rated voltage does a charger charge a lipo? GOD I MISS NI-CADS!!! Excellent video btw.
When you see 3.7v describing LIPOs, you're referring to nominal voltage which is the average voltage over the discharge curve. 3.7v is also used to describe the overall pack voltage for cells in series. i.e. 3.7*2 = 7.4v. That value has *nothing* to do with peak voltage, storage voltage, or minimum voltage. Those values for LIPO are: 4.2v Peak Voltage: A 2s pack fully charged is 8.4v (4.2v/c). Personally, I use 4.18v/c peak as a study by MIT indicates limiting peak voltage to 4.18 extends LIPO battery life by 75%. 3.75-3.85v - Storage Voltage: Manufacturers often ship LIPOs at 3.75v/c. Most chargers default to 3.85v/c for storage. It is safe to store LIPOs at any voltage value within that range. 3.3v - Minimum Discharge Voltage: You really need to stop discharging cells when they hit 3.3v as the discharge curve becomes unpredictable and you can easily exceed the floor voltage. 3.0v - Floor Voltage: Below this value, you incur permanent damage to the cell.
My father has started building Foam Core RC planes and I think I would like to try it. I'm in a similar stat to Atlguy below in that I have ordered my transmitter, but haven't figured out much else. Your information will really help me figure out how to size my motor and electronics. Thanks.
Great video sir 👍, not sure if you will read this comment or answer my question. I have one question > when talking about the weight of the plane being 1 pound . Is that the plane only or is the battery weight included in the 1 pound plane ? 🤔 Because batteries can weight quite a bit . I really enjoyed this video and I subscribed 😊 my name is Tim , I'm in Las Vegas.
Usually when calculating for performance you want to consider what's called the AUW or "all up weight" which would include the battery, fuel, cameras, or anything else not part of the airframe itself. Nice to meet you, welcome to the channel.
With over fifty years of c/l and r/c glow experience , this is THE most helpfull vid - info I have seen . THANK YOU !
Glad it was helpful!
In 10 years of tinkering around with RC, being a novice, not an expert… This was by far the best video I’ve ever seen for tying together all these values, and how it relates to overall set up well done thank you
Thank you for the kind comment and glad to help.
A little late in responding to this vid but I'v looked far and wide for information this easy to understand and helpful in my RC design efforts and nothing compares. Thanks for taking the time and for helping those of us that sometimes forget what all the numbers represent and how they can affect our planes performance and safety.
You're very welcome. Glad to know the information has been helpful.
I am sending this video to all new flyers and the clubs I belong to. It really is the best explanation of the different parts of an electric RC system that I have seen.
Thank you Joe! I appreciate it. For new flyers and gas/nitro converts electric can be daunting. I'm really happy you found the information helpful.
Very good for us old people that still have glow plug engines. These engines are slowly wearing out. Now I want to change to electric. I learned that there is no chart that gives me a .60 glow engine replacement is a “xxxx” electric motor with the same prop. So you helped me get a ideal for a good direction where to start. Thank you
You're welcome. Glad to help.
Thank you so much for making this! I have searched for months to find a simple way to design a power system that fits my different conversions from glow to electric without spending a fortune, or buying the wrong components. This gives you all the information needed to get in the ballpark in one easy location. I screenshotted the slides to share with the members of our club who may need advice in this area. Armed with this info and the understanding of KV in brushless outrunners from other videos, one can make informed choices in selecting a power system that meets their needs!
Awesome! Glad you found the info useful.
First class understandable explanations; I needed that. Thank you, the path is now much clearer for me.
Glad it helped.
I really like the Wattage to weight of plane list. that is exactly the one piece of information noone else talks about!
Yup, it's very helpful to create your own baselines for power designs. Glad you found it helpful.
Wow! Thank you so much for this reference. A great video to come back to in my project to take an old balsa .60 nitro and update it to a Pixhawk controlled EP. I'm in over my head a bit, but that's how I like it. Always learning
Awesome! Glad to help.
Awesome video explaining this stuff from a REAL engineering perspective. I'm new to this stuff and this video explained just about everything I need to know about the general power system. This has been a rare video that explains everything with this much detail. Thank you.
Glad it was helpful Thank you for the kind comment.
this video was so good thanks allot mr , i was locking for a video like this Thanks again grettings from norway
Glad it was helpful!
U the man ,I appreciate it ,perfect video for my nephew as well .
God bless take care stay safe
You're welcome...Glad to help.
I appreciate the video, thank you for making it. Very informative.
Glad you found it helpful.
Nice video for newbies like myself! I am attempting to scratch build my first plane using corrugated cardboard. Already purchased my Flysky FS-i6X 10 ch radio, was just trying to figure out the lipo battery, esc, motor, and of course, lipo battery charger. Thanks.
Awesome! I'm glad you found the video and that it helped you. Good luck with your build. Let us know how it goes.
First class video. I'm new to RC plane flying, started with a ready to fly training model which was great. Progression has now taken me to ARF models where the installation of motor, esc and battery is required. The most difficult part of this process for me has been "what size motor" to fit to the plane, especially when some manufacturers only recommend engine sizes. I found that the online conversion charts, (engine to motor) were confusing and some differed. This video stating 130W / Ib has made this much easier. The whole video has giving me a greater understanding of RC plane electric set up. Thank you.
I purchased a model from a RC club member, Thunder tiger Cessna Cardinal 177. This model is a few years old but was still in box, unmade. The model was intended for glow engines, but I will convert it for electric power. Another club member has the same model and stated to me that it would be very difficult to convert to electric due to the weight of the model. I will soon have an idea of the weight of the model and then look at motor sizing. Thank you once again.
I seriously doubt weight will stop the plane from flying on electric power. People who say things like that really don't have an appreciation for what can be accomplished with modern brushless motors and strong lipo batteries these days. In any case, I'm glad you found this video helpful. I'm surprised it doesn't have a LOT more views given the number of new people who need help with this subject and the great deal of misinformation out there even amongst experienced pilots.
Best of luck as you begin your RC journey.
@@RCVideoReviews Thank you very much. I will let you know how things go with it.
awesome video i learned a lot it was easy to follow along and im going to be using this alot since i build alot of foam board planes bravo keep em coming
Thanks! Glad to help.
helped me tremendously, Thank You.
Glad it helped!
Thanks for the great coverage on the topic. Could you provide a link to the store where one can purchase brushless motors?
Sunnysky motors are my first choice these days. Cobra and Bad Ass motors from Innov8tive designs and rcdude are my 2nd option. Finally Leopard motors from Altitude hobbies are my 3rd choice.
Great video! I might have missed it… how would you go about trying to calculate/guess run time before the battery is at the 20% or so when you want to stop using it? I think I understand starting with Wattage needed, then plugging in your battery of choice to factor your Voltage (3.7 for 1S, 7.4 for 2S), so you can then determine Amps needed. Then you want to make sure your ESC slightly exceeds that Amp requirement. Then divide ESC Amp rating by battery Amp rating to determine minimum C factor needed for battery. But how do you figure how long your selected battery will last?
For example, on a little 8 oz plane: 50W power required, using a single 1S 800mAh 30C battery gets you 3.7 Volts at 13.5 Amps required. Bump ESC up to 20 Amp, divide by .8 and you get a minimum 25C battery factor. This means technically the single 1S 800mAh 30C battery should work, but seems like it would barely work given the minimum 25C requirement.
For those who care about flight time or efficency you can also use a power tester and see the amps drawn for different props, once you have amps you can do some simple maths and get flight time. 5amphour battery for example can deliver 5 amps for 60min or 10amps for 30min 20amps for 15mins 40amps for 7.5mins ect. can be usefull for choosing battery that fits your flying style also.
Very useful video! The only thing I recommend is when 2 packs are wired parallel or in series, the voltage of the packs needs to be the same. Only use matching packs in capacity and voltage when you wire them together in series or parallel.
They don't need to be the same in series. In parallel, yes. In series, no. In series they need to be the same capacity. In parallel they need to have the same voltage.
Bummer, you're making my hobby just like my homework was 50 years ago. Didn't do then. But, thanks for explaining it so well. Really makes sense. Answers some questions that I had.PS. That chart at the end is worth printing. Can you post a pdf of it?
Thank you for your video. It's a great help to me. I'm struggling with the process of finding the right motor. When i go to sites to search for motors, it seems there are no tables summarizing all of their motors. Instead i have to open up the details of each one to get the details. And some use kv instead of total watts which i dont understand how to convert/translate. I also dont understand what the significance of the diameter of the motor is other than physically fitting in my model and probably torque is a factor too. If it has to be jigsaw puzzle examining every piece so be it, but maybe im missing something. Sites I've browsed put the kv on the main title of the product and you have to dig for the wattage. Which makes me think kv is an indicator people can recognize on sight.
Kv is definitely an indicator recognizable on site. So is the weight of the motor.
@@RCVideoReviews Can the numbers you calculated in the example tell you what kv to shop for?
Very thorough video ! Still helping me.
That's great! I'm glad you found the information helpful.
Excellent, great help with my setup
Awesome! Glad to help.
Excellent tutorial. Thanks for putting it together and making it available! I have a question about the last topic you touched on, i.e., wiring batteries in series or in parallel. So what happens to the C rating in either configuration? If for series connection the amperage and capacities stay the same does that implay that the C rating remains as well? Or is it that the 2 batteries in series now allow twice the discharge rate?
C is C and local to the battery. It doesn't know or care about the connection configuration. So don't exceed the C rating.
greatest video on youtube
What a helpful video! Thank you very much for the care you have taken to explain everything so well. Diolch yn fawr, Den, Cymru (Wales)
Mae croeso mawr i chi. Rwy'n falch eich bod wedi gweld y deunydd yn ddefnyddiol.
@@RCVideoReviews Wow, yn atebion yn Gymraeg, ! Sut ydych chi'n gneud hwnna,'te?Gwych iawn. Den
Rwy'n iawn, diolch. Hoffwn pe bawn i'n rhugl mewn ieithoedd eraill, ond rwy'n defnyddio technoleg i'm helpu i gyfathrebu â phawb sy'n estyn allan ar fy sianel. Gwerthfawrogi eich sylwadau. Gobeithio eich gweld chi o gwmpas.
@@RCVideoReviews Gwir! Da iawn, ychan! Wele'di o gwmpas. Den, Llangyfelach.
@@denismoran670 Mae'r dechnoleg y mae gennym fynediad iddi yn anhygoel. Beth bynnag, diolch am ymweld â'r sianel. Peidiwch â bod yn ddieithryn.
Great video! Do you have that slide presentation thing anywhere so we could look at?
Sure. Here's a PDF of the slides: tinyurl.com/ya84d9ye
Very excellent video, thank you! I do have a question about the example you used regarding volts and/or amps: is the voltage and/or amps at full throttle? If so, the voltage notably drops at higher throttle settings. Not sure what the conditions are when speaking of the wattage. If you could please advise it would be greatly appreciated.
Throttle and sag are not part of the equation. Volts * Amps is always Watts. Don't cross mechanical variation with the mathematical law. If under a certain load, the mechanical apparatus (battery) sags in providing the motive force of current demanded by the load, that is a mechanical deviation, not a deviation of the formula. Volts * Amps = Watts at any throttle position or battery state.
Thank you for the quick response. So in your example 975w /20volts = 48.75a, the 20 volts is the nominal battery voltage not taking into account sag correct?
20 volts is just 20 volts. If the power source is charged to peak (4.2v/c) and it's a 5s battery, the voltage is 21 volts. If under load the battery delvers 20 volts, it's just 20 volts which means it sagged 1 volt. But the math still stands--the wattage input will be 20*current.
Good video! HOWEVER, you are overestimating the power loading figures a bit IMHO, which may throw off a beginner. In an article published 1987, Keith Shaw showed that his Spitfire with aerobatic performance needed only 50W/lbs. For good aerobatic performance from the Spitfire, he suggested increasing the power loading to 60+W/lbs. He quotes the power to take off from ground to be 30-50W/lbs, sport aerobatics to be 40-60W/lbs, fast aerobatics with some 3D to be 70-100W/lbs. This is documented data, and I have no reason to dispute it. Also, he experimented with these power loading figures when we were using brushed gear motors, Co motors with NiCd batteries. Things are better now, and I have no idea why Eflite quotes these power loading figures which almost double what he has found. Pat Trittle, another electric RC aircraft designer, quoted slightly higher numbers: park flyers, trainers need 35-50W/lbs, planes with mild aerobatic performance 70-80W/lbs, all-out acrobats 100-125W/lbs, 3D performers 175+W/lbs. Eflite data you are showing match only for advanced aerobatic airplanes, but NOT for park flyers, slow scale models and trainers. After dealing with the results from Ecalc and Motorcalc, they also agree with Trittle, and show "slightly" higher power loading numbers than what Keith Shaw obtained. The reason I am elaborating the power loading is because it is the most essential design element besides wing loading to select an appropriate motor and fly the aircraft properly.
Nice video, I'm sure this will help a lot of people :)
+Partykristian Thanks! I hope it becomes a useful little reference for people learning how to put their own power system designs together.
Tried to help guys at my club understand some ideas about their receiver packs Nimh, NiCads, etc. that a voltage meter check is good but predicts little about the remaining amps in the battery. Better to measure amps used/flight x #number of flights and note if you are refilling what you used. It was like talking to a wall.
Excellent!.. thank you
You are welcome!
Thank for this very helpful video.
rbc725 You're very welcome. I'm glad you found it helpful.
Extremely helpful and I appreciate the examples used. I will use this approach in designing my power systems for some foam board planes that I am building. Several years ago, I obtained the Dynam Hawk Sky (v1) and failed to get this to fly due to an underpower engine (or so I think). It has sat in my workshop for several years now, but am starting to rekindle my interest in RC. Your video has helped with some fundamental understanding of Watts, Amps, ESC, Props, and Batteries. Hopefully, this will lead to better success!
rbc725 The Eflite guidelines are an excellent starting point. Good luck getting back in the air. Stick with it, it's a great hobby! J
Hey John, so I watched this video as you suggested and I also watched your Spitfire Power test with the Cobra 610KV motor. I ordered the Cobra 610KV motor, a 13X8X3 prop, a 3 blade Spinner, and two 4000 mah 30C 5S batteries. So the same power system you have for your Spitfire. One difference is that you used a 100A ESC and I'm planning on using the Skywalker 80A ESC. According to what you say here, I should go for 10% higher ESC rating than my PEAK Amp draw. On your Cobra 610KV Motor test you pulled about 60 amps and 1111 Watts. So here is my Math: My plane will weigh 6.4 pounds, 1111 Watts / 6.4 = 173.59 watts per pound, I think that will work. ESC needed is a minimum of 66 Amps, I'm using an 80 Amp ESC so that should be good, and the battery discharge capability is 30C x 4 amps = 120 Amps, so that should be good too. Thanks for all your help and guidance with my Power setup. This video is a huge help.
I think you're going to like that arrangement quite a bit. You'll be fine with that ESC. I think I used the 100a because I had it. You won't be beating your batteries to death with that setup either.
@@RCVideoReviews I have a question. Has your opinion on Watts per Pound needed changed from the E-Flite guideline in this video? The guideline shows 110 - 130 watts per pound is what to shoot for with a Aerobatic High Speed model. I don't agree with that range. My Sport is about 4.75 pounds and I have a power system that is 800 Watts,. That's 168 watts per pound. I love how my Sport flies and it's NOT Unlimited Performance 3D. I don't think I would like it at all if I had a 600 Watt or 126 watts per pound, power system. I think that if I had it set up for the smaller power system, I'd have to fly it FULL THROTTLE 100% of the time just to keep it in the air and I'd burn down my battery quick. So has your opinion Changed on this Guideline?
Very good question. In the video, I explicitly state it's a "good guideline to start zeroing in on where *you* need to be. For my personal flying style, I like 175w+/lb. I feel very comfortable at that power level. I agree with you on the sport flying at that ratio (168) and it absolutely is not unlimited 3d. The point in all of this is to use it as a starting point and tune for your tastes. You could re-write your own chart and raise each description up one tier.
@@RCVideoReviews Understood. I don't think I'll rewrite their chart but, like you, I think I prefer about 170 per pound or higher. That extra power could come in handy in some situations and I think the battery life would be better. Thanks again for pointing out the Big Mistake I was about to make on my power setup. It might have flown but I would probably have had a terrible flying experience. For now on I'll do MY OWN calculations and not just accept what Tower recommends. You taught me a good lesson on that. Since I'm only 2 years into the hobby, I'm still learning and you and your channel are helping me Big Time!
@@davidknutz3314 That's what this hobby should be. Sharing info, collaborating, helping. Good luck with your build.
what voltage per LiPo battery do you generally use for these calculations, the lower storage voltage or all cells at full charge voltage ?...thanks 3S_________4s____________5s____________6S_______________
Use 4.20v/c for Lipo peak value calculations.
Is it total weight of model to match the motor or ?
For watts/lb yes, you should be considering AUW or all up weight.
1 C means 1 coulomb of charge ...now charge is stored in the battery, and 1C = 1amp.s (q=it) ..If it's written as 40C means you multiply given amp rating with C rating .
Can you post a video explaining this? How a 2s lipo with a total rating or
voltage of 7.4 volts, which is made up of 2 cells rated at 3.7 volts per cell is best stored at 3.8 volts per cell or rather 7.6 volts
total. Why is this the best storage voltage that it should be "discharged down" to? How far passed the rated voltage does a charger
charge a lipo? GOD I MISS NI-CADS!!! Excellent video btw.
When you see 3.7v describing LIPOs, you're referring to nominal voltage which is the average voltage over the discharge curve. 3.7v is also used to describe the overall pack voltage for cells in series. i.e. 3.7*2 = 7.4v. That value has *nothing* to do with peak voltage, storage voltage, or minimum voltage. Those values for LIPO are:
4.2v Peak Voltage: A 2s pack fully charged is 8.4v (4.2v/c). Personally, I use 4.18v/c peak as a study by MIT indicates limiting peak voltage to 4.18 extends LIPO battery life by 75%.
3.75-3.85v - Storage Voltage: Manufacturers often ship LIPOs at 3.75v/c. Most chargers default to 3.85v/c for storage. It is safe to store LIPOs at any voltage value within that range.
3.3v - Minimum Discharge Voltage: You really need to stop discharging cells when they hit 3.3v as the discharge curve becomes unpredictable and you can easily exceed the floor voltage.
3.0v - Floor Voltage: Below this value, you incur permanent damage to the cell.
@@RCVideoReviews Thanks for your answer. you've cleared up a lot of my questions. Looking forward to your future videos.
My father has started building Foam Core RC planes and I think I would like to try it. I'm in a similar stat to Atlguy below in that I have ordered my transmitter, but haven't figured out much else. Your information will really help me figure out how to size my motor and electronics. Thanks.
Best of luck with your adventure. I would encourage you to join our discord. Lots of knowledgeable and helpful people there.
Great video sir 👍, not sure if you will read this comment or answer my question. I have one question > when talking about the weight of the plane being 1 pound . Is that the plane only or is the battery weight included in the 1 pound plane ? 🤔 Because batteries can weight quite a bit .
I really enjoyed this video and I subscribed 😊 my name is Tim , I'm in Las Vegas.
Usually when calculating for performance you want to consider what's called the AUW or "all up weight" which would include the battery, fuel, cameras, or anything else not part of the airframe itself.
Nice to meet you, welcome to the channel.
Amps of ESC?
You'll need to rephrase your question. I don't know what you're asking.
Will you please help me?
Sure.
My brain hurts !!! But thankyou !!! 🙃😉😎
You're very welcome. I hope it helped.
De Lite Jus Terned On....
😎