All the other tutorials online expects newbies to already know the desired Kv and use their charts. Thank you for providing that Kv formula as a function of wingspan.
As aircraft’s engines engineer I’m really surprised about details explained in this topic. Everything is nice and clear on the whiteboard. Very appreciate time for preparing all data and calculations, I will definitely use your tips to calculate my RC plane. Big thumbs up for future projects! Greetings from Poland 🇵🇱 💪👌
i hate lectures, but damn i can't believe i sat through 29:31 mins. this was a detail dive and i loved it, although my wing span is 21inch and motor are the smallest, it's a power efficient rc plane. using 3s li-ion battery with 3-8C only. everything was great for me in this explanation up until propeller. i think when it comes to prop i'll just take the word of seller recommendation based on motor.
My thoughts when deciding this is how much room does the plane have for a battery, how big and how many cells in series will fit first than I look at flying weight how much wing do I have to support a given weight for decent flyer and a medium to slow approach for landing. motor and prop combo is important you need to have enough power to climb and enough clearance for the prop. luckily there are many choices to make power.
Awesome Video !!! May I check one calc to be sure I got it right? I input 48 inches WS, 1.5 lbs., 100 watt/lb., 3s 1500 mAh Lipo. My results were 14 Amp Motor, 16 Amp Esc, 18C Lipo, 14,106 rpm, 1271 Kv and a 7x5 prop. Do you get the same ? Just want to make sure I got it right. You use a good number of constants/factors. Many Thanks
Yes, I placed your numbers in to the calculator I created for this on my Patreon site. Your numbers are close to what I got. I would give yourself more headroom than 2A for your ESC. A 20A ESC would be safer for example. A 7x5 prop is a good starting point, you may find yourself needing a larger prop when you measure your performance data.
Think it's better to figure it in this order.. Determine approx weight. Determine approx watts needed based on weight. 80-150w per lb Pick a ballpark prop size based on wingspan. Look for motor that supports your needed wattage with a prop that is in your size range. Motor choice will dictate esc and battery needed. It will also recommend prop pitch.
For pitch, how do you arrive at " Prop Diameter/ 1.57"? There are many Pitches' for various Props and your Calc will always be the same for any given Diameter. For example: Your Calc will always give 6.37 (or 6 ) for a 10 inch Prop. However, there are 10x6, 10x7, 10x8 ... etc props out there. Please let me know.
So great video it helps a lot do you have any videos explaining diameter and length in correlation to KV and why the length or width of a motor matters when the kv is the same with a Narrow but long VS a short and wide other than fitting it to plane
For smaller Rc plane I think it would be different. As you said 2s battery for the wingspan of 30-40in, but 2s small batteries can be also used for smaller brushless planes like 20in wingspan.
Hey man, this video was awesome! I'm building an RC air BOAT, the Dumas Swamp Buggy. Would you recommend a high or low KV/RPM for such a task? For reference, it's recommended to use a .40 up to .60 gas engine. I figured an electric motor will probably work fine in this modern age!
Hi there! I have been trying to design my own plane and I came across your video while trying to come up with my electronics system. Your video was very informative! Out of curiosity, how would you adjust your guide for a twin-engine RC plane? Also, I was thinking of using one battery but two ESCs for my configuration. Will that affect anything at all?
You can take the total amount of power required and divide this by the motor count. Then build your system/ manipulate the calculations based on the new power requirement per motor.
Great vid. question though! I have a 3d performance, 31-inch WS, yak that weighs less than 0.5 lbs. and uses 2s 600mAh. Correct me if I'm wrong but using your calculations I should be in a 4-inch prop? I'm using 15791RPM from (0.04896 x 961) - (162.66 x 31) + 20786 = 15791 and Prop diameter -0.002 x 15791 + 35.607 = 4.025 The reason I'm asking is because the plane came with an 8040 prop but is severely lacking in power. is this because I should move to a 4x2 prop?
Thank You for such an immensely useful video. Could you please share the sources/references for the formulas and the calculation tables used. Thank You.
Im gonna have to make some assumptions on how this can be applied to a less traditional design: -for a super low aspect ratio of close to 1, i imagine you would double the real wingspan to get to the "effective" wingspan ballpark. For example, a wing of 24" span, but a 1:1 AR would have wing area more similar to a 48" conventional aircraft. Extremely _high_ aspect ratios seem like they would need less conversion, though dividing by 2 for AR above 10 or so might make sense -for multi engine planes, my guess would be that the wingspan dependent numbers dont change, just the power you want per motor to achieve your desired power loading, potentially with a small fudge factor to make up for any inefficiencies caused by multi engine design
Do you have any videos comparing different brands of lipo batteries? People are always arguing over what brand of lipo is the best. Zee vs Gens Ace vs HooVoo etc…. I have yet to see a video where someone actually compares different 2S/4S/6S RC lipos (not just an on the road test), showing power draw / delivery, how long the battery will last under load, voltage drop under load, etc, with actual computerized measurements / results. Maybe this type of test can be done with some sort of desktop setup, so that all of the results will be pretty accurate.
What is a good propeller for my brushless motor of 44400 rpm at 2500 w? (2000kv, 26,5v, 120a) I'm using a 2200mAh lipo battery with 130C and a esc 1-6s for up to 120A....
Hello.Great videos. Could you (or do you have a video on the 2s+ battery to the receiver and esc. Also, a question about the thin wires for the jr connection; and if they need a thicker awg. Appreciate it.
Thanks for your quick reply. Motor is an mm1404 2900kv specs found on Amazon: KV: 2900 Unload current: 11.1v 0.5A Max Load: 5.1A Max. Power: 4A or 40W Max. Thrust : about 128g work with 4025 @8.5V Max. Thrust: about 151g work with 5030 @7.5V 10a esc 2s 7.4 450mah; 10a esc; 2s 7.4v; 450mah battery I realize that I need to view more of your videos. Thanks much. @@RCexplained
@@RCexplained Thanks for your quick reply. Motor: KV: 2900 Unload current: 11.1v 0.5A Max Load: 5.1A Max. Power: 4A or 40W Max. Thrust : about 128g work with 4025 @8.5V Max. Thrust: about 151g work with 5030 @7.5V 10a esc; 2s 7.4v 450mah. battery Some say that 20awg is what a jr conn can handle. Also, again, explaining about the connection to the motor and esc is appreciated Thank you, sir.
Hey, thanks for making this video. I just tried applying it to my first plane, a conversion of a 39“ Wingspan foam chucker. Unfortunately when I got to step 5 my prop diameter came out negative. Any ideas for what prop to try with a 250g flight weight, 2s battery, and 2700kv motor?
OKY ...SO I DID SOME CALCULATIONS , WHERE I TOOK THE TOTAL WING SPAN OF ABOUT (900CM^2 , BOTH SIDES 30CM LENGTH AND 15CM WIDTH ), AND I TOOK 2 (1400KV B.LD.C MOTORS )WITH 10INCH PROP , RADIUS OF 5 INCH DUTRING ROTATION WITH 4 INCH PITCH LENGTH , AND 2 12 VOLT LIPO BATTERIES TO POWER THEM , AND MY PLANE WEIGHT AROUND 2KG , SO THE REQUIRED LIFT FORCE IS 20N , NOW THOSE 2 MOTORS WILL INITIALLY GENERATE A BACKWARD WIND VELOCITY OF 25M/S ROUGHLY...WHICH WILL CREAT A LIFT FORCE OF AROUND 35N ( WIND DENSITY TAKEN AS 1.22KG/M^3), SO theoretically my plane should fly very quickly right?
can i use.. in my cesnna topfligh 182.. 2 batteries 4 cels 10.000 with my spectrum esc 80 amp (avian spmxae1080 smart) with 1.2 motor s[ectrum ? esc and motor resist for 8 cels? thank you
hello brother, by using your calculation i am getting a C rating around 3.76 while including 10000 mah li-ion battery with 3C. am i good to use this battery ??
do you think spinners are necessary for electric rc planes? I have a Turbo Timber Evo. and it seems that the ESC would get better airflow if the spinner was not installed.
Hi there, this was a lovely video, I was wondering though how you derived the equations you have for RPM and Prop diameter? Can you point me to a text or something that tells me where each of the terms comes from or are these equations you personally have derived out?
What category would you consider an RC plane that will be towing a 5lb payload behind it? Would this still be a "basic trainer" but we just add the weight of the payload along in the calculation?
I would design a basic trainer and not add 5 pounds to the plane as it is not actually supporting it. But add more power to the power system. You'll also want to follow wing span rules for tow planes. You can't tow a 3m plane well with a 1m tow plane.
Thanks for the reply. I should rephrase my question. I won’t be towing a glider. It’ll be a 5lb payload that will be dropped at a certain altitude. I’m thinking it’ll just be attached to the bottom of the plane.
If you were to use 4 propellers, 2 on each semi wing span, what would be the propeller diameter for the same motors, i got this doubt because the formula at 24:24 does not account for multiple motors , please help me out
Multi motors is not part of the scope here. A few calculations would be different and needed to be figured out before you get to prop size for the plane.
Have you built this calculator into excel or other spreadsheet? If so, is it available? Are there updates to the constants based on other airplane types?
All up weight should be lower than your max take off weight. Max take off weight for an aircraft makes for some sketchy flying requiring a good bit of skills.
My aircraft is around 1.5 LBs with a 30in wingspan. So according to the formulas, I need a 2s battery pack with a 150W 2200 Kv motor but I can't find that kind of motor. suggestions?
I’ve had this question for a while now, I have a 300a esc I wanted to put or pair with a 940kv brushless motor. Did a little research and I found that it’s a bad idea and the (ztw) 300a esc can only handle 800kv brushless. Is that really that big of a difference from 940kv & 800kv to damage the esc..?
Sir, can I use three 18650 batteries instead of 3s lipo battery? Is there any clear downside to it? I don't want to buy a li-po battery because I already have dozens of 18650 batteries
I have an esc that says it is 3s capable, but the motor has to be 8.5 turns or greater. All the motors I have are rated in kv and not turns, how do I know what motor I can use using kv rating alone?
All the other tutorials online expects newbies to already know the desired Kv and use their charts. Thank you for providing that Kv formula as a function of wingspan.
Glad it helps, thanks for the feedback
This is the best beginner tutorial I've seen for learning airplane electronics. Thank you!
Thank you for the comment
Excellent Beginners RC Airplane Setup Tutorial... Bookmarked.👍
Thank you 👍
As aircraft’s engines engineer I’m really surprised about details explained in this topic. Everything is nice and clear on the whiteboard. Very appreciate time for preparing all data and calculations, I will definitely use your tips to calculate my RC plane. Big thumbs up for future projects! Greetings from Poland 🇵🇱 💪👌
From one engineer to another. Thanks for the comment.
i hate lectures, but damn i can't believe i sat through 29:31 mins.
this was a detail dive and i loved it, although my wing span is 21inch and motor are the smallest, it's a power efficient rc plane. using 3s li-ion battery with 3-8C only.
everything was great for me in this explanation up until propeller. i think when it comes to prop i'll just take the word of seller recommendation based on motor.
Sounds good, thanks for the comment
I'm really thankful for this fantastic explanation!
Thank You!
Bravo, this is absolutely amazing!
Glad you like it!
Thankyou so much! I am currently building a large scale Bf109 model and this has helped in knowing i wont blow anything up!
Thanks for your lesson I really learned much
Absolutely fantastic, thanks so much!
Thank you so much Sir!
Most welcome!
My thoughts when deciding this is how much room does the plane have for a battery, how big and how many cells in series will fit first than I look at flying weight how much wing do I have to support a given weight for decent flyer and a medium to slow approach for landing. motor and prop combo is important
you need to have enough power to climb and enough clearance for the prop. luckily there are many choices to make power.
Great video, I love this format
Glad to hear it!
Thanks very much for this information.
Glad it was helpful
Great video for people getting into this stuff. Is there a book or source you used for your calculations?
Yes, I used the data that I collected over the years.
Awesome Video !!! May I check one calc to be sure I got it right? I input 48 inches WS, 1.5 lbs., 100 watt/lb., 3s 1500 mAh Lipo. My results were 14 Amp Motor, 16 Amp Esc, 18C Lipo, 14,106 rpm, 1271 Kv and a 7x5 prop. Do you get the same ? Just want to make sure I got it right. You use a good number of constants/factors. Many Thanks
Yes, I placed your numbers in to the calculator I created for this on my Patreon site. Your numbers are close to what I got. I would give yourself more headroom than 2A for your ESC. A 20A ESC would be safer for example. A 7x5 prop is a good starting point, you may find yourself needing a larger prop when you measure your performance data.
Think it's better to figure it in this order..
Determine approx weight.
Determine approx watts needed based on weight. 80-150w per lb
Pick a ballpark prop size based on wingspan.
Look for motor that supports your needed wattage with a prop that is in your size range.
Motor choice will dictate esc and battery needed. It will also recommend prop pitch.
For pitch, how do you arrive at " Prop Diameter/ 1.57"? There are many Pitches' for various Props and your Calc will always be the same for any given Diameter. For example: Your Calc will always give 6.37 (or 6 ) for a 10 inch Prop. However, there are 10x6, 10x7, 10x8 ... etc props out there. Please let me know.
This gives you a really good starting value for pitch on a prop.
So great video it helps a lot do you have any videos explaining diameter and length in correlation to KV and why the length or width of a motor matters when the kv is the same with a Narrow but long VS a short and wide other than fitting it to plane
Kv and overall size measured in weight is a good metric comparison for performance.
For smaller Rc plane I think it would be different. As you said 2s battery for the wingspan of 30-40in, but 2s small batteries can be also used for smaller brushless planes like 20in wingspan.
yeah i am about to make one for 19.2 inch wing span and i am using these calculations but keeping 2s and 3s as my battery option.
Hey man, this video was awesome! I'm building an RC air BOAT, the Dumas Swamp Buggy. Would you recommend a high or low KV/RPM for such a task?
For reference, it's recommended to use a .40 up to .60 gas engine. I figured an electric motor will probably work fine in this modern age!
I would go for a low to moderate kv value ij the range that makes sense for the cell count you wish to run.
@@RCexplained thank you!!!
Hi there! I have been trying to design my own plane and I came across your video while trying to come up with my electronics system. Your video was very informative!
Out of curiosity, how would you adjust your guide for a twin-engine RC plane? Also, I was thinking of using one battery but two ESCs for my configuration. Will that affect anything at all?
You can take the total amount of power required and divide this by the motor count. Then build your system/ manipulate the calculations based on the new power requirement per motor.
Informative
Great vid. question though! I have a 3d performance, 31-inch WS, yak that weighs less than 0.5 lbs. and uses 2s 600mAh.
Correct me if I'm wrong but using your calculations I should be in a 4-inch prop?
I'm using 15791RPM from (0.04896 x 961) - (162.66 x 31) + 20786 = 15791
and Prop diameter -0.002 x 15791 + 35.607 = 4.025
The reason I'm asking is because the plane came with an 8040 prop but is severely lacking in power. is this because I should move to a 4x2 prop?
Look at watts that you require for the performance you are expecting and then hit that mark.
Thank You for such an immensely useful video. Could you please share the sources/references for the formulas and the calculation tables used. Thank You.
Glad the info is helpful. I don't have sources or references for this info readily available. What do you need this for?
Im gonna have to make some assumptions on how this can be applied to a less traditional design:
-for a super low aspect ratio of close to 1, i imagine you would double the real wingspan to get to the "effective" wingspan ballpark. For example, a wing of 24" span, but a 1:1 AR would have wing area more similar to a 48" conventional aircraft. Extremely _high_ aspect ratios seem like they would need less conversion, though dividing by 2 for AR above 10 or so might make sense
-for multi engine planes, my guess would be that the wingspan dependent numbers dont change, just the power you want per motor to achieve your desired power loading, potentially with a small fudge factor to make up for any inefficiencies caused by multi engine design
Do you have any videos comparing different brands of lipo batteries? People are always arguing over what brand of lipo is the best. Zee vs Gens Ace vs HooVoo etc….
I have yet to see a video where someone actually compares different 2S/4S/6S RC lipos (not just an on the road test), showing power draw / delivery, how long the battery will last under load, voltage drop under load, etc, with actual computerized measurements / results.
Maybe this type of test can be done with some sort of desktop setup, so that all of the results will be pretty accurate.
I don't. This has come up before but would cost quite a bit to bring all those packs in.
Great thanks 👍
Great video!! Helps me out so much with my low wing project. Cant get out of my head that you sound like Kermit.. I’m sorry!😅
What is a good propeller for my brushless motor of 44400 rpm at 2500 w? (2000kv, 26,5v, 120a) I'm using a 2200mAh lipo battery with 130C and a esc 1-6s for up to 120A....
I can't recommend a propeller for that setup as it's not well suited for the application.
Hello.Great videos. Could you (or do you have a video on the 2s+ battery to the receiver and esc. Also, a question about the thin wires for the jr connection; and if they need a thicker awg. Appreciate it.
What specifically about the 2s battery to the receiver and ESC? Required gauge of wire is determined by current running through it.
Thanks for your quick reply. Motor is an mm1404 2900kv specs found on Amazon:
KV: 2900
Unload current: 11.1v 0.5A
Max Load: 5.1A
Max. Power: 4A or 40W
Max. Thrust : about 128g work with 4025 @8.5V
Max. Thrust: about 151g work with 5030 @7.5V 10a esc 2s 7.4 450mah;
10a esc; 2s 7.4v; 450mah battery
I realize that I need to view more of your videos.
Thanks much.
@@RCexplained
@@RCexplained
Thanks for your quick reply.
Motor:
KV: 2900
Unload current: 11.1v 0.5A
Max Load: 5.1A
Max. Power: 4A or 40W
Max. Thrust : about 128g work with 4025 @8.5V
Max. Thrust: about 151g work with 5030 @7.5V
10a esc;
2s 7.4v 450mah. battery
Some say that 20awg is what a jr conn can handle. Also, again, explaining about the connection to the motor and esc is appreciated
Thank you, sir.
Hey, thanks for making this video. I just tried applying it to my first plane, a conversion of a 39“ Wingspan foam chucker. Unfortunately when I got to step 5 my prop diameter came out negative. Any ideas for what prop to try with a 250g flight weight, 2s battery, and 2700kv motor?
It shouldn't come out negative. It should calculate to around 5-6 inches. This would be a good start, then adjust from there.
Yup, realized I made a mistake. Should have done it in a spreadsheet not on my phone. Sorry for the bother
OKY ...SO I DID SOME CALCULATIONS , WHERE I TOOK THE TOTAL WING SPAN OF ABOUT (900CM^2 , BOTH SIDES 30CM LENGTH AND 15CM WIDTH ), AND I TOOK 2 (1400KV B.LD.C MOTORS )WITH 10INCH PROP , RADIUS OF 5 INCH DUTRING ROTATION WITH 4 INCH PITCH LENGTH , AND 2 12 VOLT LIPO BATTERIES TO POWER THEM , AND MY PLANE WEIGHT AROUND 2KG , SO THE REQUIRED LIFT FORCE IS 20N , NOW THOSE 2 MOTORS WILL INITIALLY GENERATE A BACKWARD WIND VELOCITY OF 25M/S ROUGHLY...WHICH WILL CREAT A LIFT FORCE OF AROUND 35N ( WIND DENSITY TAKEN AS 1.22KG/M^3), SO theoretically my plane should fly very quickly right?
Very quickly is a relative term. With that pitch speed you provided, I would expect around 75km/h.
can i use.. in my cesnna topfligh 182.. 2 batteries 4 cels 10.000 with my spectrum esc 80 amp (avian spmxae1080 smart) with 1.2 motor s[ectrum ? esc and motor resist for 8 cels? thank you
hello brother,
by using your calculation i am getting a C rating around 3.76 while including 10000 mah li-ion battery with 3C. am i good to use this battery ??
It sounds a bit tight. Test this combo by testing for heat on the pack and you will know.
@@RCexplained sure brother,
Appropriate your response
do you think spinners are necessary for electric rc planes? I have a Turbo Timber Evo. and it seems that the ESC would get better airflow if the spinner was not installed.
You can fly the plane without the spinner
Hi there, this was a lovely video, I was wondering though how you derived the equations you have for RPM and Prop diameter? Can you point me to a text or something that tells me where each of the terms comes from or are these equations you personally have derived out?
Thanks for the comment. The formulas have been determined from a statistical data set.
What category would you consider an RC plane that will be towing a 5lb payload behind it? Would this still be a "basic trainer" but we just add the weight of the payload along in the calculation?
I would design a basic trainer and not add 5 pounds to the plane as it is not actually supporting it. But add more power to the power system. You'll also want to follow wing span rules for tow planes. You can't tow a 3m plane well with a 1m tow plane.
Thanks for the reply. I should rephrase my question. I won’t be towing a glider. It’ll be a 5lb payload that will be dropped at a certain altitude. I’m thinking it’ll just be attached to the bottom of the plane.
In that case you will have an extra 5 pounds on the plane. Treat it as it is part of the plane. You will want the weight over or close to the CoG.
If you were to use 4 propellers, 2 on each semi wing span, what would be the propeller diameter for the same motors, i got this doubt because the formula at 24:24 does not account for multiple motors
, please help me out
Multi motors is not part of the scope here. A few calculations would be different and needed to be figured out before you get to prop size for the plane.
Hi there I got to the prop formula but it doesn't matter how many time I calculate it I still don't get 14" ? Am I doing something wrong ?
Throw it in to an online math calculator to do the math for you. Or use the patreon member spreadsheet.
Have you built this calculator into excel or other spreadsheet? If so, is it available? Are there updates to the constants based on other airplane types?
There's a spreadsheet on my patreon link. There's no other airplane types built in.
Is there any difference between all up weight and maximum take off weight of an aircraft?
All up weight should be lower than your max take off weight. Max take off weight for an aircraft makes for some sketchy flying requiring a good bit of skills.
My aircraft is around 1.5 LBs with a 30in wingspan. So according to the formulas, I need a 2s battery pack with a 150W 2200 Kv motor but I can't find that kind of motor. suggestions?
I can really only find one or the other. like a motor that's 2200 Kv but 340 W, or 1000 Kv 150 W
I’ve had this question for a while now, I have a 300a esc I wanted to put or pair with a 940kv brushless motor. Did a little research and I found that it’s a bad idea and the (ztw) 300a esc can only handle 800kv brushless. Is that really that big of a difference from 940kv & 800kv to damage the esc..?
I need more information as to why an esc manufacturer is placing a limit on Kv. What is the true limit that is driving this?
Hello. I am trying to build an RC glider but I don't know where it belongs on the power performance level chart. Could you please help?
Guys are going anywhere from 50 to 150 w per pound.
Sir, can I use three 18650 batteries instead of 3s lipo battery? Is there any clear downside to it? I don't want to buy a li-po battery because I already have dozens of 18650 batteries
It is possible but will depend on the specs of the 18650's and the system current draws.
I have an esc that says it is 3s capable, but the motor has to be 8.5 turns or greater. All the motors I have are rated in kv and not turns, how do I know what motor I can use using kv rating alone?
what 'd you mean you wanna know the RPM of your motor ??
Now I see why I burned my motor twice
I think this calculation would be more useful if you used wing loading (LBS/SQ. IN.). This way it would be easily applied to any plane model.
Só uma dúvida e melhor montar um kit 6s ou 3s
Depends on what you are doing. If you can go 6s.
Please make a same video on
Long range rc plane ❤️❤️♥️♥️🔥🔥🔥
does someone know of a reliable 30A 300W 1300kv motor? I'm lost.
Sk3 series
Would you be interested in throwing all of this in an excel sheet?
Yes, I did on my Patreon Page inside the RC Calc Sheet
could you share excel to calculate ?
I do here: patreon.com/rcexplained otherwise the formulas are provided.
...FS-i6 for airplane