Newb to the hobby and need advice! :D

[eddie200112]

So I've wanted to build a multi-rotor for some time and finally decided to do it. I bought a turnigy talon 1.0 625mm hex frame. and from there I want some input before I go any further. My main desires for this craft will be that I can carry a camera or some sort of video that I can stream down from the craft, and I also want it to be able to reach the max altitude I can get it to. Beyond that there would just be nice things id like to have such as having it able to hold position and ive heard of sonar sensors to help it autoland which I think would be neat but not a must have. So ive looked at how these guys are put together and the general parts I need but having never worked on these before I know like most tech there will be lots of nuiances I am not prepped for. I build PC's and I know theres always quirky things u would not think about if u haven't done it before. That being said I quite tech savvy and not afraid to get into tech specs etc. phew..... So first ive been looking at products mostly at hobbyking. Are the products they sell decent I was looking at turnigy engines.. maybe a 420kv 22pole motor or a 390kv I know they would need a large prop. but not sure if that's best for getting the most altitude. and then I need the most advice on flight controllers and the radio transmitter and receiver. Do I need a channel for each motor? Thanks looking forward to everyones advice.

 

[Electro 2]

"Turnigy engines.. maybe a 420kv 22pole motor or a 390kv"
Those are too big for your 625. They are also wound for 6 cells, waaay too much for a craft of this size. The size of the frame is almost incedental, it's weight that matters most. For your 625 I'm guessing it will weigh in at about 5, possibly 6 lbs, or so with camera/gimbal on board. You'd be looking at 35xx motors with a 4 cell wind, say 500 to 750 Kv.

 

[eddie200112]

do you not approve of the turnigy engines? are they junk? also what do you mean 35xx motors is that a model number for the turnigys? Also why wouldn't more power be better I would think the heavier 6s battery would be ok with the stronger motors..

 

[gtranquilla]

For those intent on DIY approach.... bear in mind that these are complex systems that can rapidly lead you into a lot of trial and error (sometimes referred to as R&D) a garage full of nice but useless spare parts and 1/2 built MRs that will not fly well.
So in the end you likely will not be saving much money when compared to the purchase of a fully engineered ARF or RTF system. As far as the DIY approach, don't buy premium full price products..... buy from HongKong to keep your R&D costs under control.

TURNIGY MOTORS: There is nothing wrong with these motors... its just that you selected ones intended to drive props of a diameter that is too large for your existing MR airframe. P
ick another Turnigy Multistar motor or select a different MR frame size or buy frame extenders to accomodate larger prop diameters.
And check out the classified section of this MR forums where you will find excellent bargains on items that other DIY'ers bought not krealizing they were, in many cases, heading down the wrong path with their designs!!!

do you not approve of the turnigy engines? are they junk? also what do you mean 35xx motors is that a model number for the turnigys? Also why wouldn't more power be better I would think the heavier 6s battery would be ok with the stronger motors..

 

[gtranquilla]

Yes..... to achieve optimal system efficiency it is important to move up the voltage level when moving up to heavier MRs. BUT......
I recommend starting out with something small and inexpensive as the small ones can take a beating yet remain cheap to repair.
From my experience MR Hobby is a journey..... not a destination.... enjoy the ride and have fun along the way.
You can always sell off your used equipment as you move up the ladder.

do you not approve of the turnigy engines? are they junk? also what do you mean 35xx motors is that a model number for the turnigys? Also why wouldn't more power be better I would think the heavier 6s battery would be ok with the stronger motors..

 

[eddie200112]

Yeah I had already considered buying longer arms for each rotor to accommodate the larger props. I really don't want to start out small as I wont be happy with it, and wont be able to do what I want with it and just end up building a new one. So if altitude and the ability to hold a camera is a priority would the larger props and lower kv motors still be bets if I just make the arms longer or can I achieve the same with smaller? Side note... Any one ever wire a small solar panel on the MR to increase flight time, or would that be negligible...? Thx

 

[Electro 2]

"or would that be negligible..."

Ha! Less than negligible. Your mid-size will pull about 200-250 watts in a hover, double that in climb.

 

[mikhael47]

Hey Eddie, this is my first post on the site and one might wonder why I chose to reply to you. I think this is merely an attempt to guide you away from a very frustrating path you seem to be moving towards. I too build PC's for a living, but not exactly in a mom and pop shop, and I don't build desktops. I run large networks and build very huge and expensive computers. NONE of the skills I have learned along my 20 year career are transferable to this hobby. I have flown planes, coaxial helis, fixed pitch helis and collective pitch helis. That being said, multirotors are a WHOLE new ball game to me.

I tend to research the HELL out of things before I start a project. This equips me with the knowledge prior to taking on the development and implementation of a project. I can tell you that I have the garage full of broken vehicles and spare parts the others talk about. This isn't due to my sub par intelligence, nor does it have anything to do with the fact that I suck at building flying things! LOL

The issue is, this hobby really does take a lot of trial and error no matter how "handy" or "savvy" you might be. It requires understanding over many disciplines including physics (aerodynamics, lift, thrust, drag and weight), electronics (soldering, electrical math for voltages etc) and RF systems amongst others. Each of these topics take a lot of time to learn. Impatience leads us to trial and error.

This doesn't even begin to touch the topic of actually learning to fly these beasts.

Now, I may be sounding bleak to some, but to me, and YOU Eddie, I suspect anyways, this is a challenge that you are obviously smart and capable enough to tackle. You just need the patience to do the job as right as you can, the first time, or deep enough pockets to do the trial and error thing (not to mention very thick skin).

If someone (on a forum) gives you some advice that you feel doesn't apply to your particular situation, don't discard said advice. Use your google-fu and search the forums for alternative perspectives that either support your position, or the position of the person giving you advice and make your decision accordingly. There is a plethora of information available and honestly, a lot of it contradicts itself. This is also the nature of the hobby, there are very few right ways to get a job done, and very few wrong ways, but there are a ton of "in between" ways to get a job done.

Welcome to the world of multi-rotors and make sure you post pics and videos of your adventures (especially the bloopers).

Mik

 

[mikhael47]

oh and to answer your questions about the solar cell augmentation of your power system, even with the most effective PV cells available today, you would have to have a panel larger than your quad to provide you enough juice to run one motor. As an example, to get 434w of output, the panel would weigh over 40lbs... Not to mention the cost involved.

 

[PeterLester]

Good comments Mickhael,

Regarding solar panel.....
a) if they need to point up towards the sun, they will prevent MR prop airflow from getting thru!!!
b) Even if it were possible, it would function like a barn door when your MR flys, affecting the flight in crazy ways.

BUT: A large solar panel recharging station located at a club flying site where there is no electrical utility service would be a good alternative to each person wearing down their vehicle alternator and battery.

Hey Eddie, this is my first post on the site and one might wonder why I chose to reply to you. I think this is merely an attempt to guide you away from a very frustrating path you seem to be moving towards. I too build PC's for a living, but not exactly in a mom and pop shop, and I don't build desktops. I run large networks and build very huge and expensive computers. NONE of the skills I have learned along my 20 year career are transferable to this hobby. I have flown planes, coaxial helis, fixed pitch helis and collective pitch helis. That being said, multirotors are a WHOLE new ball game to me.

I tend to research the HELL out of things before I start a project. This equips me with the knowledge prior to taking on the development and implementation of a project. I can tell you that I have the garage full of broken vehicles and spare parts the others talk about. This isn't due to my sub par intelligence, nor does it have anything to do with the fact that I suck at building flying things! LOL

The issue is, this hobby really does take a lot of trial and error no matter how "handy" or "savvy" you might be. It requires understanding over many disciplines including physics (aerodynamics, lift, thrust, drag and weight), electronics (soldering, electrical math for voltages etc) and RF systems amongst others. Each of these topics take a lot of time to learn. Impatience leads us to trial and error.

This doesn't even begin to touch the topic of actually learning to fly these beasts.

Now, I may be sounding bleak to some, but to me, and YOU Eddie, I suspect anyways, this is a challenge that you are obviously smart and capable enough to tackle. You just need the patience to do the job as right as you can, the first time, or deep enough pockets to do the trial and error thing (not to mention very thick skin).

If someone (on a forum) gives you some advice that you feel doesn't apply to your particular situation, don't discard said advice. Use your google-fu and search the forums for alternative perspectives that either support your position, or the position of the person giving you advice and make your decision accordingly. There is a plethora of information available and honestly, a lot of it contradicts itself. This is also the nature of the hobby, there are very few right ways to get a job done, and very few wrong ways, but there are a ton of "in between" ways to get a job done.

Welcome to the world of multi-rotors and make sure you post pics and videos of your adventures (especially the bloopers).

Mik

 

[Silverburn]

I started like you, not long ago. It took 4 weeks before I bought a part.

Those 4 weeks were spent reading the forums, understanding the technology (batteries, Rx/Tx, motors, prop angles, FC's, ESC's etc). And spent many hours doing "what ifs?" in ecalc.ch.

I now have 2 birds - one heavy, one small/medium. Both fly well on defaults. My next learning stage is PID's!

 

[eddie200112]

OK thanks so far for the advice everyone, im ready to order so far im getting 6 690kv turnigy multistar motors and (6 BEC 30A ESC's also turnigy multistar) my biggest confusion is still with the flight controllers. I want the vehicle to be able to hover where I leave it if that's possible but not sure what type of controller I would need for that. Also would be nice if it could self land if that battery dips to much or loses radio contact, also don't know if that's possible. Also I would like to maybe get the FPV camera thing down but don't want to go to expensive $1000 is pretty much my max. THANKS!

 

[eddie200112]

OK so if I have 6 motors that run at 16A with a max of 22A and have 30A ESC's on each that means I should have a power supply that can give out 180A (30Ax6) correct? But I see most of the best batteries only go up to 65C with a burst max of 130C does that mean I need 2 or 3 of those batteries then to get the right amount of power?

 

[gtranquilla]

IMHO - Typically one can get by quite well with 2 batteries in parallel to power the MR but rarely will require 3 in parallel.
Depending on motor voltage rating I use two 3S or two 4S batteries in parallel, each with a capacity of 5000 mAH for a total of 10,000 mAH which equates to 20 amps for 30 minutes or 40 amps for 15 minutes (my preferred design flight time).
Each of my batteries have a discharge rating of not less than 35 C which is typically more than adequate when there are two in parallel.

Please keep in mind the the MR flight controllers typically inhibit the vertical climb rate in Attitude and GPS modes which limits the instantaneous current draw on your entire system unless you are overloading your MR with too much payload.
All bets are off though when you fly in Manual mode which allows excessive current draw due to extreme climb rates.

In any case the real answer to your questions is best determined by running various scenarios using ECalc for Multicopters.
http://www.ecalc.ch/xcoptercalc.htm?ecalc&lang=en
Keep in mind that the results will be much more conservative for the newer, higher efficiency 22 pole pancake style motors which the eCalc developer has not yet anticipated or designed it for.

OK so if I have 6 motors that run at 16A with a max of 22A and have 30A ESC's on each that means I should have a power supply that can give out 180A (30Ax6) correct? But I see most of the best batteries only go up to 65C with a burst max of 130C does that mean I need 2 or 3 of those batteries then to get the right amount of power?

 

[gpforet]

It may help you to understand the C ratings for LIPO batteries.

There are better sources to get the details but here's the basics:

There are 3 primary specifications to the LIPO packs. The first determines the number of cells in series. Each cell has a range from 2.7v (fully discharged) to approx. 4.23v (fully charged). These are available from 1S to 6S. So do the math. The numbers of cells required is usually determined by the speed you need the motors to turn, which is also dependant on the prop diameter and pitch.

So, the first number is the S rating of the battery = Voltage

The second is the mah rating. This is the storage capacity of the battery. Think of it like a gas tank. Popular Mah ratings seem to be between 2000 mah - 6000 mah. The mah designation stands for milli amp hour meaning how much current can be drawn from the battery in 1 hour until the gas gauge is at 0. So, a 4000 mah battery can deliver 4000 millamps over an hours time and then be completely discharged. FYI, 1000 ma = 1 amp.

So, mah rating is the size of the gas tank.

The third rating, the C rating is a factor used to describe the maximum current drain the battery is capable of without destroying the battery.

As an example, let's take a 4000 mah battery with a rating of 25C-50C. The first C rating tells you how much you can pull from battery continuously. The second C rating describes the max you can pull for very short periods of time. So, in the example above, a 4000mah (or 4 amp hour) battery with a 25C rating can continuously drain at a rate of 25 times the mah rating of the battery. In this case, that would be 100 amps. the 50C rating says that for momentary loads, the battery can be drained at 200 amps. In this example the "gas tank" only holds 4 amp/hours, so draining at 25C would completely empty the gas tank in 2.4 minutes.

This is theoretical and does not account of losses in cabling as well as the need to retain 20% of the battery's capacity as to not destroy it.

Your 30A ESCs will not continuous draw 30A until your motor demands it so it's really your motors current draw curve which will determine the battery capacity for X minutes of flight. And how your select and apply the motor and accompanying current curve will be based on AUW and prop selection.

As a practical example: I fly a fairly heavy (7.5 lbs AUW) F550 hex with tiger motors and 10x4.7 APC props. I fly with 2 4000 mah 25c/50c Turnigy nanotech batteries and when flying for AP purposes, I get about 8 minutes of flight before my batteries reach 75% discharge.

To sum up: ESCs are selected to match motors, motors are selected for power required, power required is based on AUW, batteries are selected to meet motor and flight time requirements. Once all this is done, props are selected to match motors, batteries, and flying style.

 

[eddie200112]

would I get more power by putting 2 2s 12800mah 40-80C batteries in series, or by 2 4s 5000mah 65-130C batteries in paralell

 

[gpforet]

2800 more mah with the 2 2s in series, but you would have no redundancy. With the batteries in series, if one goes out, down you come.

 

[Dewster]

I started like you, not long ago. It took 4 weeks before I bought a part.

Those 4 weeks were spent reading the forums, understanding the technology (batteries, Rx/Tx, motors, prop angles, FC's, ESC's etc). And spent many hours doing "what ifs?" in ecalc.ch.

I now have 2 birds - one heavy, one small/medium. Both fly well on defaults. My next learning stage is PID's!

Lol! I spent a month researching parts too. YouTube really helped, because some posted their setups and advised what worked and what didn't. I wanted to carry a Sony Nex camera and compared ships that were capable and have flown setups to support the weight.

I also read a lot about props, motors, ESC, lipo batteries (still learning to understand 'em), gimbals, FPV cameras, video transmitters, antennas, radio frequencies. It seems like a lot, but your interest will drive you to learn more.

 

[eddie200112]

what if I buy larger booms for my turnigy frame currently the booms are 250mm what if I got 400, 500, haha ive even seen 1000mm booms. would that make the craft unstable? I know if I went a bit larger I could use larger props, so maybe more lift?

 

[Electro 2]

Generally, longer boom/larger craft are *more* stable than small. Weight (mass) is one factor, leverage moment of the arms is another. Doubling the length of the arms you might run into other issues, (strength/rigidity of the central plate), but stability won't be one.