Replies to This Discussion

Permalink Reply by Stephen R Mann on January 27, 2013 at 8:35pm

Props.  Buy eight because you're going to go through a few while learning to fly.

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Permalink Reply by Doss Miller on January 27, 2013 at 8:38pm

I figured that would fall under the hardware I had mentioned. Thanks for the suggestion to buy more though I will make it so.

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3D RoboticsPermalink Reply by Joshua Ott on January 27, 2013 at 8:55pm

I assume you have a lipo charger and a prop balancer if you've been flying RC already.

Mission Planner needs a machine running Windows or Linux, a laptop or tablet is most convenient.

I would strongly recommend installing LED position lights on your quad, maintaining orientation can be a bit difficult with multi-rotors.

A test stand is almost a requirement, in my opinion, a well tuned craft saves a lot of money and keeps morale in the green zone. 

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Permalink Reply by Doss Miller on January 27, 2013 at 9:31pm

Yes to all of that. Good idea on the test stand. As far as power to weight ratio for picking a motor setup I read that I should try to maintain a 60% weight to available thrust ratio to have a good responsive craft. Meaning that say I have a max thrust of 1000g my total craft weight should be 600g. How does that sound?

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3D RoboticsPermalink Reply by Joshua Ott on January 27, 2013 at 10:05pm

Honestly, most multi-rotors, by their nature, have plenty of power. I would think about your system design in terms of prioritizing the weight. 

For example: If you want to maximize endurance and don't need to lift a heavy payload, then put most of your weight budget in the battery and choose lightweight motors/ESC, airframe, etc.

What kind of mission is your bird going to be used for?

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3D RoboticsPermalink Reply by Joshua Ott on January 27, 2013 at 10:29pm

Doss, 

I didn't mean to ignore your question. If you shoot for a hover at %40-50 throttle, that's probably going to leave you PLENTY of climbout authority, and keep your motors in their efficiency happy spot. I would focus amp draw to thrust curves for your motor/prop/voltage decision, versus max thrust.

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Permalink Reply by Doss Miller on January 28, 2013 at 4:24pm

Is there any type of formula to figure this out without actually just buying stuff and trying it.

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3D RoboticsPermalink Reply by Joshua Ott on January 28, 2013 at 4:36pm

Look for a retailer who will provide you with the info. Something like this.

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Permalink Reply by Doss Miller on January 28, 2013 at 5:43pm

The motors I have picked out have a chart like that but no throttle percentage. I can only assume that the #'s provided are at 100% throttle.

What do you know about those T motors?

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3D RoboticsPermalink Reply by Joshua Ott on January 28, 2013 at 9:56pm

It's probably safe to assume that the figures advertised are max thrust, and you can extrapolate down from there to get a general idea of %50 throttle, just remember motor curves are just that -- a curve.

I'm going to try the T-motors myself when I make my next investment in components, I have no first hand experience yet. In general, I think large diameter slow kv motors swinging big props are the way to achieve long endurance and low vibes.

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Permalink Reply by Doss Miller on January 29, 2013 at 5:11am

Not to mention quieter operation as well. Swinging bigger props at lower speed does not sound like a pack of pissed off insects. I had picked out some 1000kv motors but now think I will take a look at some 870ish motors.

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