Newb questions4.

[Jussi]

ok so I got a zyma x5c as a gift and just had a blast. Its a great little trainer but now I'd like to go up in class and build one. I'd like to make one primarily for aerial videos using my go pro. I've been reading as much as I can by myself but it's a bit overwhelming. So forgive if some of my questions have been asked more than once or a dozen times.

1. How do you properly gauge the power of a motor? My initial thought was the kv rating but I've read that those numbers Don't really paint a clear picture and that they don't mean much if you're comparing between different brands as each company has its own standards of arriving at those figures.

2. How do I size the proper esc and battery?

3. How do I know what size and pitch props I should use? Assuming I know the frame size and other components and I know what I want it to do. In my case slow and stable.

4. Are there any carbon fiber hexacopter frames with retractable landing gears? I really like the tarot 650 sport but want one with a hexa frame.


5. What is a good transmitter. I'd like to get the best one I can afford now so it will grow with me when I transition to better rigs. So something that's not super complicated for a newb to use and get the basics down but has the capability of doing more advanced stuff in the future. Ideally it would be less than $350. I was thinking the Taranis or dx8 but if you guys think the dx9 is significantly better I'd would raise my budget for it.

 

[econfly]

Good questions.

1. How do you properly gauge the power of a motor? My initial thought was the kv rating but I've read that those numbers Don't really paint a clear picture and that they don't mean much if you're comparing between different brands as each company has its own standards of arriving at those figures.

Motors are best judged in combination with a propeller. For example, here is a link to a T-Motor spec sheet. The motor in the link comes in a few versions. Here is the table of performance data for one of them:

Note the voltage specification (this is "3S" and "4S" voltage at a nominal 3.7 volts/cell) and propeller information. For each prop and voltage combination you have power consumption (amps, watts), lift (thrust in grams), and RPM. The common measure of "efficiency" is here too (grams of thrust per watt). This table also tells you a lot about the manufacturer's intended use of the motor. For example, you probably would not want to use a 10 inch prop with 4S power, though that could be a good match at 3S.

If the manufacturer does not provide this level of detail for a motor then don't buy it. T-Motor and KDE are two makers that provide the detailed information you need (just for example).

2. How do I size the proper esc and battery?

Sizing the ESC is straightforward given the information above. Say, for example, you plan a 4S build with 8-inch props. From the table you can see that the maximum amp demand is 6.9A. An ESC that can handle 10 amps would be fine, though it's always nice to have a little head room, so picking a 15 or 20 amp ESC that can handle 4S power would be a good idea.

3. How do I know what size and pitch props I should use? Assuming I know the frame size and other components and I know what I want it to do. In my case slow and stable.

To pick your motor/prop combination you need some idea of "all up weight" -- the weight of your copter with battery, camera, gimbal, and anything else you might want to fly. This takes some trial and error thinking because the battery you pick will depend on the motor/prop/ESC, and that depends on the weight which depends on the battery, etc. Your ideal setup should be one where the all up weight demands about 50-60% thrust from your motors to hover. For example, The motor above on a quad copter at 4S with 8-inch props produces 345g of thrust at 50% throttle. Multiply by 4 for a quad and you have about 1.4kg or around 3 pounds of total thrust. That's a good estimate of what the all up weight should be for the build.

4. Are there any carbon fiber hexacopter frames with retractable landing gears? I really like the tarot 650 sport but want one with a hexa frame.

There are tons frames out there and many either have retracts or you can add them.

5. What is a good transmitter. I'd like to get the best one I can afford now so it will grow with me when I transition to better rigs. So something that's not super complicated for a newb to use and get the basics down but has the capability of doing more advanced stuff in the future. Ideally it would be less than $350. I was thinking the Taranis or dx8 but if you guys think the dx9 is significantly better I'd would raise my budget for it.

My favorite radio is the Futaba 14SG. For your budget, I would probably pick the DX8, which is also very nice.

 

[Jussi]

Thanks econfly!!! A lot of great info. I had to read some it more than once to completely sink in.

So in general where does one start when building a copter? It seems all the parts are dependent on the parts you already chose but you have to start somewhere. Assuming you know what you want the craft to do, which piece is chosen first?

 

[econfly]

I start with the camera. If you are going for an FPV build then perhaps start with a frame you would like to fly. Then I start adding up the weight of things I know I want: frame, camera gimbal, electronics, etc. Then, as a really rough estimate, I assume batteries are going to be about one-third of my all-up weight. Then I look at motors, think about the lift I need to hover, and aim at a 50% throttle hover. Add it all up again, repeat as needed, etc. For power, higher voltage is generally better. Above a 450 quad just go with 6S LiPos. Use 4S for a small quad. I don't see the point of 3S on anything. I have a slight preference for higher RPM / smaller props, all else equal, but generally stick to the middle of the spec sheets unless you have a good reason to do otherwise.

There are so many options out there it is hard to know where to start. If you have some idea where you are headed post it up here and people can tell you what has worked for them.

This is a very interesting time in the small quad market that can carry a GoPro or similar camera. 3DR is offering up their SOLO -- I think it's $1400 with a GoPro capable gimbal (GoPro not included) -- and it has a TON of features. DJI has a Phantom 3 coming out and for $999 you get it all (quad, radio, battery, 1080p camera, gimbal, HD video to your phone/tablet, etc). There are several more in this same space. It's fun to build, but there is also a lot of value out there so look around.

 

[Motopreserve]

Really great post!

I'm a big fan of the Taranis - and would say that although it is "advanced," if you're new to the hobby, it probably won't be any more confusing that a typical radio.

The computer tailoring that you do for your various models, and the features and programming within those models, is priceless to me.

In terms of where to start, @econfly is right - figure your payload, and then you sorta pick your major components to handle that load, backing in to a solution by picking and adding up the weight of various components. I like to do a spread sheet that adds it all up for me - making changes is easy and keeps track of your AUW so you can see where you've gone wrong

Tarot offers some inexpensive frames in all the configurations. You may not need a hex to lift the gopro and gimbal. Depends on the rest of the build I'm sprucing up a 680Pro for sale because I ended up needing more lift - but in revisiting the build, it's got some nice features.

 

[Jussi]

Ok so I'm somewhat following with a build on a podcast. It's a budget 450 build which I like because I'm sure there will be a few crashes as I familiarize myself with the copter. What is a budget friendly but decent motor and props for this build. I want to carry a gopro and possibly a gimbal. I'd like to get good flight time as well but I'm expecting the world in this budget. Here are some of the parts they're using. Tell me if u agree or disagree.

Oh also I went and ordered a DX8. The one thing I splurged on seeing as I can always take that to the next step when the time comes. So I'll also need a receiver recommendation. Do they make budget receivers with telemetry that will work with the dx8?
Frame:
Dead Cat or "X-Alien" Frame $18.00

Motors:
EMAX 2213-935KV (Pack of 4)) $58.31

ESCs:
F-30A FIRE RED SERIES SIMONK-(RAPIDESC) ($10ea x 4) $40.00


POWER DISTRIBUTION BOARD 2OZ COPPER $2.00

Propellors
HQ PROP 8X4.5 SF CARBON COMPOSITE PROP ($4.38 X 2) $8.76

Flight Controller
KK2.1.5 Flight Controller $19.00

Gimbal: Unknown
Camera: GoPro