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May 21, 2019, 08:41 PM
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How to design a plane around a motor?


Wasn't sure if this forum was the correct one, but I couldn't find anything better.

I work for a company that builds brushless motors ranging from 12v, 20v, 40v and higher as well as the batteries for them.

I thought it would be cool to build a "company" plane using the motors and potentially the batteries that we make. The batteries are Li-Ion so that is my first question. Can Li-ion be used for a plane? It would be preferred to use a battery that we make, but if it turns out we need to use a lipo that would be OK too.

The next question is how do I determine the size of plane for the motor(s) we have? It seems that typically builders start with the plane and then find a motor that fits it. I have to go the other way, but not sure where to start.

The only starting point I have is I would like something similar to a warbird style plane or an acrobatic style plane.

I have tried searching the web but I'm not really sure what questions I need to ask to know where to look.

I am working on getting the specs of the motors which I am sure will help some.

Any thoughts and ideas would be great.
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May 21, 2019, 09:49 PM
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balsa or carbon's Avatar
Quote:
Originally Posted by riptyde
Wasn't sure if this forum was the correct one, but I couldn't find anything better.

I work for a company that builds brushless motors ranging from 12v, 20v, 40v and higher as well as the batteries for them.

I thought it would be cool to build a "company" plane using the motors and potentially the batteries that we make. The batteries are Li-Ion so that is my first question. Can Li-ion be used for a plane? It would be preferred to use a battery that we make, but if it turns out we need to use a lipo that would be OK too.

The next question is how do I determine the size of plane for the motor(s) we have? It seems that typically builders start with the plane and then find a motor that fits it. I have to go the other way, but not sure where to start.

The only starting point I have is I would like something similar to a warbird style plane or an acrobatic style plane.

I have tried searching the web but I'm not really sure what questions I need to ask to know where to look.

I am working on getting the specs of the motors which I am sure will help some.

Any thoughts and ideas would be great.
Yes , we'll need to know all the specs for the motors ...... and all the specs for the batteries as well .

Do you have an experienced RC airplane flyer who will fly the plane or assist in flying the plane ? If not , I recommend building a trainer suitable for an unassisted first time RC airplane flyer . A warbird or acrobatic style plane will be difficult/impossible for an unassisted first timer to fly .



A suitable trainer has the following characteristics :

1) Able to fly slowly . Slow flight gives you time to think , time to react , and time to correct a mistake .

2) Stable flight . A stable plane will fly right-side-up , straight-and-level ..... all by itself . When it is upset by an external force ( such as an inexperienced RC flyer at the controls ) , after the upset it will return to stable flight .... all by itself .
May 21, 2019, 10:09 PM
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balsa or carbon's Avatar
As an example of a very slow flying stable plane , here is one I've built . You can see in the video how easy it would be for a beginner to fly :



Lightweight 40" wingspan FT Old Fogey-ish (2 min 58 sec)
May 22, 2019, 08:00 AM
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Quote:
Originally Posted by balsa or carbon
Yes , we'll need to know all the specs for the motors ...... and all the specs for the batteries as well .

Do you have an experienced RC airplane flyer who will fly the plane or assist in flying the plane ? If not , I recommend building a trainer suitable for an unassisted first time RC airplane flyer . A warbird or acrobatic style plane will be difficult/impossible for an unassisted first timer to fly .
Yes, I will be a member of a club this summer learning to fly. I don't have too much concern about being able to fly this plane when it is done since it's going to take awhile to complete given work and family life and finding time to build it. In that time I will be learning.

Quote:
Yes , we'll need to know all the specs for the motors ...... and all the specs for the batteries as well .
I will see what info I can get.
May 22, 2019, 09:13 AM
An itch?. Scratch build.
eflightray's Avatar
Seems a little odd you quote specific motor voltages, usually quite a broad voltage range is quoted. Even then the voltage into so important, the max safe amps and watts is usually quoted.

Would I be right in assuming that the motors are not specifically designed for model plane, boat, car usage ?

.
May 22, 2019, 09:19 AM
Registered User
Riptyde

One question that most folks on here WON'T ask is are you designing / building motors for FOC control or scalar / 6/ 12 step control? (Assuming they are all BLDC type anyway)

"Most" hobby ESC's are scalar control with the only thermal control being at the ESC itself, so you'll end up with crappy control methodologies with a high end motor. Unless you have your own speed control, which, then you get into weight issues.
May 22, 2019, 09:25 AM
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Thread OP
Quote:
Originally Posted by eflightray
Seems a little odd you quote specific motor voltages, usually quite a broad voltage range is quoted. Even then the voltage into so important, the max safe amps and watts is usually quoted.

Would I be right in assuming that the motors are not specifically designed for model plane, boat, car usage ?

.
Correct the motors are not for planes boats or cars. The voltage has more to do with which battery they are optimized for. Technically all the motors could work with all of the battery voltages, but the performance would not necessarily be the best. I'm not an EE so I could not explain why that is, it is what I have been told.

I'm looking into what the watts and amps are. Hopefully will get some feedback soon.
May 22, 2019, 11:58 AM
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Thread OP
So I just talked with one of our engineers and he's willing to help me out with the electrical side of things.

What specific specs on the motor and battery do I need to pay attention to?
what I see a lot are KV, amps, watts, stater size?

Same question for batteries. Ah, Volts?

The Engineer can help me get this information.
May 22, 2019, 12:16 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by riptyde
So I just talked with one of our engineers and he's willing to help me out with the electrical side of things.

What specific specs on the motor and battery do I need to pay attention to?
what I see a lot are KV, amps, watts, stater size?

Same question for batteries. Ah, Volts?

The Engineer can help me get this information.
Motors : kv , watts , amps , weight , shaft diameter .

Batteries : voltage , Ah or mAh , C rating , weight .
May 22, 2019, 01:02 PM
AndyKunz's Avatar
I0 (no load current) and winding resistance (mohm) are helpful to determine motor performance with propellers.

Andy
May 22, 2019, 01:29 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by riptyde
Yes, I will be a member of a club this summer learning to fly. I don't have too much concern about being able to fly this plane when it is done since it's going to take awhile to complete given work and family life and finding time to build it. In that time I will be learning.


I will see what info I can get.
Cool , learning at club can be a good path to flying an RC airplane .

Another path you can take if you want to get a jump start to flying , is getting a parkflyer type trainer and fly at a local park , school field , soccer field , etc . You will eventually need a transmitter for your project , so getting a parkflyer trainer will provide that transmitter .

Horizon Hobby makes several very good parkflyer trainers that are very easy to fly . The computer transmitter you would get with the trainer can be used for additional future aircraft ( airplanes , helicopters , quadcopters ) , the computer transmitters have memory for up to 250 models .

IMO , the easiest to fly trainer from Horizon Hobby is the UMX Radian . https://www.horizonhobby.com/umx-tra...ology-eflu2980
This is the least expensive computer transmitter that will work with the UMX Radian and 249 possible future aircraft :
https://www.horizonhobby.com/dx6e-6c...-only-spmr6650
If that is too expensive , you can get this non-computer transmitter for $55 (with the $15 coupon savings) :
https://www.horizonhobby.com/dxe-tra...-only-spmr1000

Other very good trainers available at Horizon Hobby have a system called SAFE . SAFE has three switch operated modes you can choose from : beginner , intermediate & experienced . Learning to fly with a SAFE equipped plane is like : learning to crawl , then learning to walk , then learning to run .

This is probably the most popular trainer with SAFE : https://www.horizonhobby.com/product...nology-hbz4480

HH even has warbirds with SAFE , like this one : https://www.horizonhobby.com/airplan...h-safe-hbz5650
Or this acrobatic plane has SAFE : https://www.horizonhobby.com/product...-basic-efl7150


The learning to crawl , then learning to walk , then learning to run ..... approach works well for learning to fly , but it is also a good approach for learning to build planes . I recommend practicing building airframes starting with something very simple , then work your way up to more complicated builds ( like warbirds & acrobatic planes ) . If that makes sense to you , let me know and I'll be happy to help you build your first simple airframe .
May 22, 2019, 01:39 PM
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GWRIGHT's Avatar
While there are numerous items that can be usefull,.. you can boil it down to just mass and kv to keep it simple. Mass determines how much power (how many watts) the motor will withstand, and KV determines the prop for various voltages. A motor can generally be ran at 3 watts per gram indefinitely, although some of us prop them for 5 or 6 watts per gram and use throttle appropriately. so,.. at bare minimum, a motor is good for about 100 watts per ounce easily, and most can be pushed much further, but you're safe at 100/ounce. Then the KV is going to determine prop size to get there. Run the motor on various voltages, and find out what prop size gets you to 100 watts per ounce at various voltages. Then you can determine the size plane based on the performance you get for each prop at each voltage. I've had various power setups I liked and designed planes specifically for a power system many many times. Easier to go the other way, but this direction is easily achieved.
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May 22, 2019, 02:56 PM
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Thread OP
Quote:
Originally Posted by balsa or carbon
Motors : kv , watts , amps , weight , shaft diameter .

Batteries : voltage , Ah or mAh , C rating , weight .
great thanks!

Quote:
Originally Posted by AndyKunz
I0 (no load current) and winding resistance (mohm) are helpful to determine motor performance with propellers.

Andy
Aslo, thanks.

Quote:
Originally Posted by balsa or carbon
The learning to crawl , then learning to walk , then learning to run ..... approach works well for learning to fly , but it is also a good approach for learning to build planes . I recommend practicing building airframes starting with something very simple , then work your way up to more complicated builds ( like warbirds & acrobatic planes ) . If that makes sense to you , let me know and I'll be happy to help you build your first simple airframe . .
Thanks. The jumping right in is not a big concern for me. I already have Speckrum DX6e and a flight test plane. Plus the club has several trainers to use.
As for building, this too is not a scary thing for me. I tend to jump into big projects and figure them out as I go. I anticipate a lot of crashes, rebuilds, and adjusting on something light this. Its just how it goes.

Quote:
Originally Posted by GWRIGHT
While there are numerous items that can be usefull,.. you can boil it down to just mass and kv to keep it simple. Mass determines how much power (how many watts) the motor will withstand, and KV determines the prop for various voltages. A motor can generally be ran at 3 watts per gram indefinitely, although some of us prop them for 5 or 6 watts per gram and use throttle appropriately. so,.. at bare minimum, a motor is good for about 100 watts per ounce easily, and most can be pushed much further, but you're safe at 100/ounce. Then the KV is going to determine prop size to get there. Run the motor on various voltages, and find out what prop size gets you to 100 watts per ounce at various voltages. Then you can determine the size plane based on the performance you get for each prop at each voltage. I've had various power setups I liked and designed planes specifically for a power system many many times. Easier to go the other way, but this direction is easily achieved.
Great info. Thanks. I will get with the engineers and see what we can figure out.

Thanks for the great help so far guys. Very much appreciated.
May 22, 2019, 03:05 PM
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balsa or carbon's Avatar
Quote:
Originally Posted by riptyde
Thanks. The jumping right in is not a big concern for me. I already have Speckrum DX6e and a flight test plane. Plus the club has several trainers to use.
As for building, this too is not a scary thing for me. I tend to jump into big projects and figure them out as I go. I anticipate a lot of crashes, rebuilds, and adjusting on something light this. Its just how it goes.
Sounds like you have a good plan and a good attitude !

Just curious : which FliteTest plane do you have , and did you build it yourself ?
May 22, 2019, 03:19 PM
Registered User
If you have not already done so, simply looking at e.g. the Horizon or AMain or Tower Websites and going through the specifications of electric planes listed will give you an idea about plane sizes and what size motors and ESCs are used in such applications. You might be able to find a plane that would be compatible with a product that is manufactured by the company you work for. Seems like a fun project!


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