too low throttle - what is the impact?

[wolph42]

From what I've read your throttle @ hoverspeed should ideally be between 50-60%, over that and your craft becomes too irresponsive and might not take off at all.

But too low? In my case between 30 and 40%, does it become difficult to fly?

Here the ecalc result (Im using NTM motors which aren't in ecalc so I tried several similar motors):

View attachment 17026

 

[SoCal Blur]

The will make the copter very twitchy. Your power to weight ratio is a bit high. Looking at your flight times, something is very off. You might try increasing the size of your props to 12" that should get you closer to 50% and should increase your flight times. If your frame doesn't allow for 12" props, try a higher KV motor. I'm sure there is more tweaking to be done.

 

[wolph42]

The will make the copter very twitchy. Your power to weight ratio is a bit high. Looking at your flight times, something is very off. You might try increasing the size of your props to 12" that should get you closer to 50% and should increase your flight times. If your frame doesn't allow for 12" props, try a higher KV motor. I'm sure there is more tweaking to be done.

thanks for the response. I would have guessed that 'twitchy' is what happens, but I liked it verified. The frame allows 10" max so no go there. As for the tweaking, yes the flight times seemed a bit low, but what can I usually expect?

 

[SoCal Blur]

I think a good goal is to shoot for around 8 - 10min mixed flight time. if possible. Just for fun, try changing the motor to a higher KV motor and see what it does to your times and hover %.

 

[wolph42]

Ill do that. 8-10 still isn't really a lot now is it...? I was hoping to get around 20min. mixed.

 

[SoCal Blur]

I think we all hope for 20min mixed. And, it is possible but harder to achieve - you'll have to get the right combination of components, weight and power. That is why eCalc is so helpful because you can model all of the possibilities. I'm sure it's easier with the smaller multis as well to achieve those numbers.

 

[econfly]

My view is you have to try it to find out. What matters is thrust response to throttle near hover. If that thrust curve is flat (i.e., you need a lot of throttle to get a little movement in thrust) then the flight controller will need to behave differently than if thrust is responsive. How the controller handles that depends, of course, on the controller and its software. The motors, props, and ESCs in combination will determine the thrust at any given throttle position. All three are evolving rapidly in today's market. Past rules of thumb (e.g., target a system with hover around 50-60%) are becoming less relevant. I would aim for a build that hovers around 50%, but lower might work just fine. As for flight times, north of 20 minutes is easily achievable for lighter system (just look at the Phantom 2). For heavier multis it seems like 15 minutes or so is the sweet spot.

 

[wolph42]

I'll dig into it. Thank you!