Flydigital
Member
That looks similar but seems like a slightly different version. Maybe it's just the casing that's different.
https://pixhawk.org/modules/pixhawk
Next machine?
- Thread starter davey_b
- Start date
https://pixhawk.org/modules/pixhawk
Flydigital
Member
Good to know if I destroy this one in a ball of flames!
Motopreserve
Drone Enthusiast
Since it's open source (both hardware and software) - there have always been alternatives to the 3DR branded FCs. The guy at readytoflyquads.com puts together a pretty good package, from what I can tell.
Ok so if I went with a dji f550 frame and the pixhawk FC then I guess the next thing to think about is the motors and the ESC. Any suggestions? I'm looking for a fairly stable platform for videoing which would be my main consideration here but it would be nice to be able to flick a switch to be aggressive to either have a bit of fun or get somewhere quick.
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Drone Enthusiast
The best way to design a system is to determine what the total weight (AUW) will be. Figure out what the payload will be (camera and gimbal, FPV etc) and make a list.
Then you can start to hone in on what the power requirements will be. The max prop size for f550 is 10", so any motors you look at should be listed with those props in mind. Many motor manufacturers will list thrust specs. After calculating AUW, you should be able to hover at 50% throttle.
For a new build, I always start a spread sheet to start plotting numbers in. That way you can keep track of weight and cost.
The easiest way (maybe slightly more expensive) is to go the DJI packaged propulsion kit made specifically for the f550.
Then you can start to hone in on what the power requirements will be. The max prop size for f550 is 10", so any motors you look at should be listed with those props in mind. Many motor manufacturers will list thrust specs. After calculating AUW, you should be able to hover at 50% throttle.
For a new build, I always start a spread sheet to start plotting numbers in. That way you can keep track of weight and cost.
The easiest way (maybe slightly more expensive) is to go the DJI packaged propulsion kit made specifically for the f550.
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I hear that kids can do that 
Ok, so here's a rough run down of what I'm thinking. Bear in mind I've no clue about this at this stage so comments/suggestions/abuse welcome! Not sure if I need to add a wee satellite receiver thing for the GPS in the FC?
View attachment 24735
View attachment 24735
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Motopreserve
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couple thoughts....
Do you already own 3S batteries? If so, I could see sticking with those. But if not, you might want to think about going 4S right off the bat. You'll probably appreciate it later - and it will give you more options for propping up/down depending on payload.
I don't have any experience with those motors, but I'd do some research. Hobby king is hot or miss - with a lot more miss sometimes. An alternative would be the Sunnysky equivalent - which have always been solid - especially for the money.
Make sure the ESCs are flashed with the firmware you want - unless you plan on getting the tool to do it yourself (or have it already).
Do you already own 3S batteries? If so, I could see sticking with those. But if not, you might want to think about going 4S right off the bat. You'll probably appreciate it later - and it will give you more options for propping up/down depending on payload.
I don't have any experience with those motors, but I'd do some research. Hobby king is hot or miss - with a lot more miss sometimes
. An alternative would be the Sunnysky equivalent - which have always been solid - especially for the money. Make sure the ESCs are flashed with the firmware you want - unless you plan on getting the tool to do it yourself (or have it already).
Thanks, I'll look at different motors. Do you recommend staying away from hobby king for most things then?
Don't own any batteries so can get whatever. I have read that slower prop speed with larger props tends to give more stability which is what I'm after which is why I went for 3S but I can go with whatever.
Do you think motors of that spec will lift ok? I'd rather have more power than struggle.
Don't own any batteries so can get whatever. I have read that slower prop speed with larger props tends to give more stability which is what I'm after which is why I went for 3S but I can go with whatever.
Do you think motors of that spec will lift ok? I'd rather have more power than struggle.
Motopreserve
Drone Enthusiast
You definitely don't want struggle. I think you'd be able to be choosing between 9-10" props, so not drastically different in terms of stability.
I found a video on YouTube showing a thrust test for the sunnysky 2212 980kv with various props, and 3S and 4S. Do a quick search. Should help you decide.
Hobby king is good for the basic stuff. Connectors, silicone wire, LEDs etc. but their branded products can be flaky. Some people have great luck - others don't. The Nano-Tech batteries have been great for me.
I found a video on YouTube showing a thrust test for the sunnysky 2212 980kv with various props, and 3S and 4S. Do a quick search. Should help you decide.
Hobby king is good for the basic stuff. Connectors, silicone wire, LEDs etc. but their branded products can be flaky. Some people have great luck - others don't. The Nano-Tech batteries have been great for me.
Thanks, had a look at that. Can you tell me if I'm on the right track with these calcs?
Weight of craft 1885g.
1885 x 2 = 3770
Add 20% for safety = 4524
So I'm looking for 4524g of thrust. Split over 6 props that = 754g of thrust per prop.
So I'd be fine with any motor and prop combination that gave over 750g of thrust. Look OK?
Weight of craft 1885g.
1885 x 2 = 3770
Add 20% for safety = 4524
So I'm looking for 4524g of thrust. Split over 6 props that = 754g of thrust per prop.
So I'd be fine with any motor and prop combination that gave over 750g of thrust. Look OK?
Motopreserve
Drone Enthusiast
Nope. You want to take the total weight of the craft, and have that total weight equal the thrust the motors are capable of lifting at 50% throttle. So at 2000g, you'd need motors that can produce 333g of thrust at 50%. I'd ad a bit more like you mention - probably shoot for 2100-2200g and you'd be right in line with the sunnysky in the video.
Thanks, I was meaning 750g at 100% so I think we were coming to the same conclusion from different ends.
So looking at that video if I put these motors on with a 4S battery and 10x5 carbon props I'd be getting 460g of thrust of each motor.
Two questions:
1 What's the advantage in this situation of using 4S battery? Does it just deliver more voltage so the motors spin faster and thus produce more thrust? Don't you drain the battery quicker? Or is the battery bigger since it's 4 cells but then that gives you extra weight which of course is a disadvantage?
2. With the props how does changing the size and pitch affect things like the stability and thrust? I've read bigger props mean more stable flight it's less aggressive. Is that the same as you increase the pitch?
Thanks
Dave
So looking at that video if I put these motors on with a 4S battery and 10x5 carbon props I'd be getting 460g of thrust of each motor.
Two questions:
1 What's the advantage in this situation of using 4S battery? Does it just deliver more voltage so the motors spin faster and thus produce more thrust? Don't you drain the battery quicker? Or is the battery bigger since it's 4 cells but then that gives you extra weight which of course is a disadvantage?
2. With the props how does changing the size and pitch affect things like the stability and thrust? I've read bigger props mean more stable flight it's less aggressive. Is that the same as you increase the pitch?
Thanks
Dave
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The main advantage to the 4S is that if you move past this build - you will likely want 4S (or bigger). I think it's been played out enough that 3S works for some builds, but most people, if they stick with the hobby, quickly move past 3S to 4S. So it's more of an investment thing.
It also provides higher voltage, so the capability of the machine is extended. If you decide to add weight, r move to a heavier machine altogether, you won't be stuck.
The larger props (if power correctly) will give you more lift due to more surface area to move air. It's not quite as simple as 1 is more stable. I have had smaller props react more stable in heavy wind - because they are cutting the air more often, and not being affected by the external forces as much. But obviously the trade off is that they are spinning faster/more to provide the lift - which could translate to vibrations on the craft. Larger props spin less, may create less vibes (if balanced of course) and may translate into "more stable." But they will be more subject to wind gusts, etc.
Pitch will be less an issue. It will act like more/less scoop to the air. There is a formula I'm sure for how much air it will move changing the pitch. Unfortunately I don't know if offhand.
Hope that makes sense. Very non-scientific
It also provides higher voltage, so the capability of the machine is extended. If you decide to add weight, r move to a heavier machine altogether, you won't be stuck.
The larger props (if power correctly) will give you more lift due to more surface area to move air. It's not quite as simple as 1 is more stable. I have had smaller props react more stable in heavy wind - because they are cutting the air more often, and not being affected by the external forces as much. But obviously the trade off is that they are spinning faster/more to provide the lift - which could translate to vibrations on the craft. Larger props spin less, may create less vibes (if balanced of course) and may translate into "more stable." But they will be more subject to wind gusts, etc.
Pitch will be less an issue. It will act like more/less scoop to the air. There is a formula I'm sure for how much air it will move changing the pitch. Unfortunately I don't know if offhand.
Hope that makes sense. Very non-scientific
Motopreserve
Drone Enthusiast
Not bad. And considering I have two 3S 5000mah batteries that I now only use for an FPV monitor (way overkill), 4S is a bargain comparatively.
Check hobby king for the nano tech batteries. They are very reasonable and have held up well. Readymaderc also has decent branded batteries.
Check hobby king for the nano tech batteries. They are very reasonable and have held up well. Readymaderc also has decent branded batteries.
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Drone Enthusiast
Are you asking whether you need a GPS for the pixhawk?