What FC

[Bartman]

If you use an HV BEC to power the Pixhawk, then you will lose the battery voltage and current draw data. Unless, you set up a voltage divider, which is very easy to do, and is what I do on most of my aircraft. That gets you voltage. I just don't worry about current normally. It really doesn't concern me much. But, even that can be done if you really want. I can build a current sensor that will be good for unlimited voltage, and 100A current, with exactly ZERO resistance, and ZERO chance of failure, if somebody wants.

it should be an off the shelf option at this point, why would a potential user need to rely on a custom power module built at the discretion of a software developer in order to get the full functionality of a system?

I'm not saying to not balance the props. What I'm saying is that there's a point of diminishing returns. And also too much focus on prop balance while ignoring other issues that affect the image is problematic. I've seen many cases where people spend lots of time balancing props, but still get vibration soon as they are actually flying. They probably think they need to spend even more time balancing, but that's not the problem. The problem is, as I've said many times, that aerodynamic forces, namely disymmetry of lift, will cause even the best balanced prop to vibrate anyway. You can't stop it, unless you went to a complicated articulated rotor, which nobody is doing. Therefore, you must have an effective vibration damping system for the camera. If this system is effective for the aerodynamic vibrations, then it will also be effective at eliminating the remaining minor vibes coming from a prop that hasn't had hours spent balancing.

nobody is saying that propeller vibrations can be eliminated in their entirety but it's a waste of time to build out this entire system while ignoring the airframe vibrations that come from the mechanics of having an unbalanced mass rotating at a high frequency.

Yes, I know many of the concepts I present are revolutionary, but it's because I come at this from a firm grasp of science and engineering, and usually backed by data. Too much of this industry relies on a black-magic mindset.

BS Mechanical Engineering, Rutgers Univ., 1991 along with a lifetime spend designing/building/operating stuff

I've seen several situations where people have crashed, because they spent so much time balancing props and motors, got everything perfect, no vibes. So they hard mount the Pixhawk. And then they actually go outside, and fly at 10m/s, and the thing starts shaking like hell, and crashes, and they can't understand why.

I don't see how an example where a FC is installed poorly can justify not taking the time to fully balance propellers.

and if, as you say, isolating the camera is the better effort for your time, why make one job harder by neglecting to do the other? why ignore the fact that with zero isolation a camera can still be found to get vibration free images?

 

[R_Lefebvre]

it should be an off the shelf option at this point, why would a potential user need to rely on a custom power module built at the discretion of a software developer in order to get the full functionality of a system?

I agree. Unfortunately, I have no influence in this. However, I'm not just a software developer. You should consider me a System Engineer. I do it all. If somebody needs help with systems integration, I'm the guy.

nobody is saying that propeller vibrations can be eliminated in their entirety but it's a waste of time to build out this entire system while ignoring the airframe vibrations that come from the mechanics of having an unbalanced mass rotating at a high frequency.

I'm basically saying the same thing. It's a waste of time to build out this entire system, while ignoring the airframe vibrations that come from aerodynamics.

why ignore the fact that with zero isolation a camera can still be found to get vibration free images?

I don't believe that. Have an example of a camera with no isolation, flying either fast forward, or in winds, that has no vibration?

 

[jdennings]

it should be an off the shelf option at this point, why would a potential user need to rely on a custom power module built at the discretion of a software developer in order to get the full functionality of a system?

True that. Rob's not wrong in saying 6s+ can easily be done with Pixhawk, (power modules can easily be sourced on e-bay for 6s and above), yet it usually requires some research and some soldering of connectors. Tinkering, in other words. Not a big deal, even a plus for some hobbyists. But if you want RTF you are out of luck. The ESC issue reported earlier (

PH is out for me. I read this thread and it scares the hell out of me. http://multirotorforums.com/threads...troller-compatibility-list.20587/#post-182161

) is also a problem, although again it can be dealt with.

This is one of the weak links of 3DR and Pixhawk, a company that remains stuck several years back and in DIY mode, ignoring anything beyond 11" props and 4S, despite sponsoring the development of the best and most versatile FC on the planet. You'd think that with the hegemony of DJI (and, possibly soon, Gopro on the low end) and their VCs they'd do something about it, but it sure doesn't look like it. Not knocking the company down btw, it's all to easy for me to comment from an armchair. But it is disapointing. And the time I've wasted because of that is enormous, even though it's not all for nothing as I've learned more.

nobody is saying that propeller vibrations can be eliminated in their entirety but it's a waste of time to build out this entire system while ignoring the airframe vibrations that come from the mechanics of having an unbalanced mass rotating at a high frequency.



BS Mechanical Engineering, Rutgers Univ., 1991 along with a lifetime spend designing/building/operating stuff



I don't see how an example where a FC is installed poorly can justify not taking the time to fully balance propellers.

and if, as you say, isolating the camera is the better effort for your time, why make one job harder by neglecting to do the other? why ignore the fact that with zero isolation a camera can still be found to get vibration free images

Agree. For good stable camera footage, the entire chain needs to be looked at and the result will be as good (or bad) as the weakest link.

Chain includes, at the very least, prop balancing, motor balancing, good vibration isolated FC, good vibration isolated camera/gimbal. Forget any of these and the result, while acceptable depending on requirements, will be sub-optimal nonetheless.

 

[Old Man]

Rob,

Understand I used two extremes for the example. I'm not one to spend too much time on balancing props either. Hub imbalances with our stuff is negligible (skinny hubs) so only blade work is necessary. Spending a bit isolating the FC components also goes far to a nicely performing copter. Securing wire connections even more.

As for Pixhawk being stuck in the past and limiting to 11" props. perhaps that's just for the average consumer that hs been proven to be extremely stressed operating just the basic system. Keep it small and the crash expenses down might be one way of looking at it.

I seriously doubt all that many people have any concept of just how much further than the 11" propeller model the Pixhawk is being used. 15" 22", 29", and even larger. In private the Pixhawk is being used on extremely large MR's, but people are not going to share that stuff publicly because they are using their proprietary designs to gain market advantage and use MR's in ways most would never, ever consider.

For the most part, the name manufacturers are selling toys, even at the 1,000mm size classes outfitted with system integral gimbals selling for 6 times the cost to produce. There's only a couple of controllers that can be viewed as tools for the serious professional. By serious I mean those that are willing to invest the time, effort, and design research go beyond the general functionality standards delivered with the average FC while designing flight platforms intended to fill extremely niche functions. For them the next step up from Pixhawk are systems designed by aerospace companies like Lockheed.

 

[jdennings]

I've always wondered where the military contractors like Lockeed are and how their FC's compare. Lockeed's Kestrel FC starts at $8k (and that'st just a start, add $5k for a ground station, $7k for an SDK just to develop custom stuff, another $5k for video), their Indago looks cool, but how would it really compare to a well tuned frame with Pixhawk? My admitedly very wild is: not much better, if better at all ... Looks like they do have video tracking, though. Cool ...

 

[Pumpkinguy]

Just ordered super x and OSD. Thanks for your help guys. Your advise was all taken into account. SuperX just seemed to be the right fit for my technical skill level.