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MultiRotor project, please help!

#1
Hi, I'm a complete newbie in the world of multirotors and relatively uninitiated in the RC world. However, i am doing a project at college that requires me to build and fly a drone as a platform for something relatively heavy. I know you are all going to suggest i start off with something less complex but i was looking at the Electrohub Y6 with power pack D (I'll be very careful and get raining if required).
I need to know:
  • What sort of weight it can carry?
  • Are there any other mulitrotors that would be a better choice for a large payload?
  • What are all the parts i need to buy, starting with absolutely nothing?
  • Will i be able to achieve this for under £500 ($770ish)?
  • What sort of flight time can i expect?
I hope all of you wonderful people can give me some advice.
Thanks in advance ;)
 
#4
I'd like it to be able to carry roughly 1kg (2.2lbs), although i can probably adapt the design a little bit to make it lighter if necessary. The more lifting power the better though.
 

razor02097

Rogue Drone Pilot
#5
A few more details would be nice. Do you have to lift it and fly around? For how long? will it be attached to the frame or on a tether? Are you limited by size or AUW?

In my experience Most of the 400/500 class multi-rotors can carry around 300g without too many issues. Most people just stick a gimbal and a camera on them and go nuts. A Y6 or X8 could carry a lot more weight but you still might be pushing it a bit at 1kg. Once you find a frame that will handle the payload you need to size the props and motors to get the amount of thrust you will need. There are a few calculators you can use. Here is one to play with that might give you some ideas. http://www.ecalc.ch/xcoptercalc.php?ecalc&lang=en (it will nag you about signing up... just exit those windows to use the tool)

The problem isn't lifting the weight. It is lifting it safely.
 
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#6
First disclaimer: I am still new to the hobby.

After some internet searches I found a calculator that output roughly a 6.5lb lift weight for the power pack D. I used http://adamone.rchomepage.com/calc_motor.htm and plugged in the info from the store. You will have to lift your battery, vehicle, and payload under this weight.

Can't help so much with flight time, but I would guess with that much weight you are looking around five minutes on a good day.

As for what you need:
Frame Kit
Power Pack
Flight Controller (Naze32 or similar)
Receiver
Transmitter
Battery(ies)

I would suggest getting a NanoQX and starting to practice now for flying. If you want to be proficient or at least not dangerous when you get the larger vehicle in the air.
 
#7
It has to be able to lift the payload and fly around. As long as possible. The payload would be attached to the frame. No size limit, but i would like to keep the cost reasonable. What sort of vehicle should i be looking at? I don't mind spending a bit more than first planned.
 
#8
Thanks for working that out, didn't think of working the motors' lift power. I'm starting to think i may need something larger as 6.5lbs for the whole arrangement doesn't sound like enough for the multirotor to remain nimble.
I might have to look at buying the NanoQX, i don't want to watch in horror as my multirotor eats dirt.
 

razor02097

Rogue Drone Pilot
#9
Something I want to add. You would be better off with a lower KV motor swinging a larger prop and a 4S or larger battery. You want to have enough grunt to get it off the ground and be able to maneuver.

The power pack D hex has the prop size about right but the motors wouldn't be happy if you ran them with that prop on 4S... If you were to use the calculator and plug in something like 900KV on 4S X 6 motors with a 10X4 prop it would yield about twice the static thrust with the same prop. Of course it is all theoretical so it doesn't take into account real life...
 

razor02097

Rogue Drone Pilot
#11
So, theoretically, the Y6 with power pack D components would be fine if i switched out the motors?
The motors are the most expensive part usually. If you want different motors it would probably be better to buy everything À la carte. Best thing to do is to figure out what motor/prop combo would suit your needs at a certain cell count, then get ESCs that will supply enough current, then get a battery that will supply you with enough capacity and amperage to run the whole deal.
 
#12
The motors are the most expensive part usually. If you want different motors it would probably be better to buy everything À la carte. Best thing to do is to figure out what motor/prop combo would suit your needs at a certain cell count, then get ESCs that will supply enough current, then get a battery that will supply you with enough capacity and amperage to run the whole deal.
Ok cool, do you have any suggestions for specific components?
 

razor02097

Rogue Drone Pilot
#13
Well I can point you in the right direction... There are data charts pretty much everywhere. For instance...

If you're going with a 3S setup something like the sunnysky 2212 motor with an 11X4.5 prop according to the chart on this page should produce 960g of thrust.

There is also this motor which shows that with a 13x4 prop it produces 80g more thrust but only consumes about 3W more power. But that is a really big prop... you may have limitations depending on the frame you choose.

Of course the thrust numbers are for each motor so with a quad you would multiply by 4, a hex by 6, octo by 8. I'm sure in the real world the numbers will also vary but if you get a good motor/prop combo that balances longevity (lower wattage) with power (more thrust) you'll have a well balanced machine.

Hope that helps.
 
#14
Well I can point you in the right direction... There are data charts pretty much everywhere. For instance...

If you're going with a 3S setup something like the sunnysky 2212 motor with an 11X4.5 prop according to the chart on this page should produce 960g of thrust.

There is also this motor which shows that with a 13x4 prop it produces 80g more thrust but only consumes about 3W more power. But that is a really big prop... you may have limitations depending on the frame you choose.

Of course the thrust numbers are for each motor so with a quad you would multiply by 4, a hex by 6, octo by 8. I'm sure in the real world the numbers will also vary but if you get a good motor/prop combo that balances longevity (lower wattage) with power (more thrust) you'll have a well balanced machine.

Hope that helps.
Ok, time to do some serious research then. So that SunnySky 2212 motor's thrust would be multiplied by 6 to get 5.76kg? What sort of battery should i be looking for to keep it in the air for the maximum amount of time? Thanks for all of your help.
 
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razor02097

Rogue Drone Pilot
#15
The battery type will depend on the power needs of your system and the weight it can carry. Once you decide on what motor you want you'll be able to size an ESC for that motor then you can decide how many cells based on the motor.

Now you can add up all of the power requirements to get a total amp draw of all motors. So for example if each motor pulls up to 20A and you have a hex that means you should size a battery that can supply at least 120A.

So now you can balance the C rating with the mAh rating. A 5000mAh battery at 25C will supply 125A. The way I got that was multiplying the C rating by the mAh rating then divide by 1,000.
 

Snarls

Gravity Tester
Mentor
#16
So, theoretically, the Y6 with power pack D components would be fine if i switched out the motors?
Just a word of caution for this project. Do not attach the payload using ropes. Attach it directly to the frame and stand far away from it on take off. Most of us know about the Y6 incident with Flitetest... These things are dangerous and with large payloads you will be using larger, stiffer, props than can do serious damage.

That being said, getting a NanoQX is a good choice to get you familiar with how to fly multirotors. You can also get a simulator cable for the TX you get so you can practice on the computer.

I'm going to hop on ecalc and see what kind of setup I can generate for your budget.
 
#17
The battery type will depend on the power needs of your system and the weight it can carry. Once you decide on what motor you want you'll be able to size an ESC for that motor then you can decide how many cells based on the motor.

Now you can add up all of the power requirements to get a total amp draw of all motors. So for example if each motor pulls up to 20A and you have a hex that means you should size a battery that can supply at least 120A.

So now you can balance the C rating with the mAh rating. A 5000mAh battery at 25C will supply 125A. The way I got that was multiplying the C rating by the mAh rating then divide by 1,000.
Thanks for the explanation, really helpful. This is turning out to be even more of a project than i had anticipated but this forum is certainly helping!
 
#18
Just a word of caution for this project. Do not attach the payload using ropes. Attach it directly to the frame and stand far away from it on take off. Most of us know about the Y6 incident with Flitetest... These things are dangerous and with large payloads you will be using larger, stiffer, props than can do serious damage.

That being said, getting a NanoQX is a good choice to get you familiar with how to fly multirotors. You can also get a simulator cable for the TX you get so you can practice on the computer.

I'm going to hop on ecalc and see what kind of setup I can generate for your budget.
Ok, so for safety's sake, is there a more stable layout i could use to save any impromptu amputations?

Also, is the Hubsan X4 an acceptable trainer?
 
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Snarls

Gravity Tester
Mentor
#19
Ok, so for safety's sake, is there a more stable layout i could use to save any impromptu amputations?

Also, is the Hubsan X4 an acceptable trainer?
You could do a standard Hex, but I can't confirm that layout is any more stable than a Y6. Just mount a payload as if you would mount a camera; solid and unable to change the CG of the multirotor. If you plan on only lifting 1kg, it should not be as big of a problem as lifting a large P47 like David wanted to.

How long do you have to do your project? The Hubsan X4 is an ok trainer, but the nanoQX is unanimously the best trainer out there. If Flitetest parts can't do the job for you, you may end up building a much larger machine to get long flight times (>15 mins) with the payload. If that occurs you will have to be vary safe and cautious proceeding from a small trainer to a large, potentially deadly machine. So if possible, you may want to start with a small trainer like the X4 or NanoQX, then proceed to a larger trainer quad like a basic electrohub just so you are ready for the larger machine. Saying that, the flight controllers used on these larger builds can pretty much fly for you (sorta), but I don't want you or anyone's safety compromised because you have no idea whats going on in flight.

I want to see this project succeed big time, because that's a project I want to have :p but safety with the bigger machines is a big concern, especially these days.
 
#20
Ok, I agree that safety is the most important thing so I'd best start training now. I have until June next year to be able to fly it. Not looking for any sort of aerobatics, just simple hovering and slowly moving around. The payload i designed is a fixed unit that can be adjusted on the ground but remains static in flight. I was wondering whether a standard hex with angled arms to vector the motors would help stabilise it?