MultiCopter Mechanics/Engineering/Design - The Basics + - Discussions

I thought it might be a good thread to discuss the basics and a little more about what goes into building a MultiCopter. I am new to this, so I have nothing to offer except my inquisitive nature to get a discussion going. I'm hoping this might become a one-stop source for others just starting out with the same questions. So here goes:

1. Is Bigger Better in terms of size of frame, motors, etc. Does size mean more stability? What else about size? "Does size matter"?

2. Motors - is it safe to say that the smaller Kv value is going to give me more torque and therefore more lifting power? 2a. Is there a formula (power to weight ratio or other rule of thumb) to be used for the size of payload (camera, etc.).

3. Props - CW, CCW. . . ??? Don't the motors have to spin CW or CCW??? I'm confused. Can someone explain everything there is to know about props? What do the numbers mean (6X4, etc). 2b. Prop sizing and pairing witht the overall size of Copter/Motors - what works?

4. Should I start out with a small, inexpensive ARF to learn the basics before jumping into a scratch build? Which ARFs are recommended. I want to mount a small, lightweight camera to have some fun with.

5. Is a Hex more stable/powerful than a Quad and a Oct more powerful/stable than a Hex? What are the benefits/drawbacks.

6. What else is there?

Are there any books on the subject?

Other noobies - feel free to add your questions here.

Much appreciated! - Joe

1. Is big better. Well that's what she asked? LOL. It all depends on what you want to do and how much you want to spend. Small is lighter and cheaper. Bigger is more complex, more expensive and more stable and you might survive an engine failure. You will crash, no matter how hard you try not too. Even the pros eat it from time to time. It's just part of the hobby.

2. Not to up on motors. I usually buy what they offer for my kit. Haven't built a custom copter yet. Have to wait an earn more brownie points before I ask the wife. LOL.

3. Smaller props need to spin faster and larger props can spin slower to get the same lift. Again my 3DR kit recommends 10/4.5 props or the 11 inch can work, with larger motor. Currently I run 850 and the bigger ones are 880. The second number on the prop is the distance where curve comes in on the prop. Props need to be made to spin CCW. So every other motor and prop has to spin CCW. This is to balance the copter and keep it from spinning. Acts like the tail rotor on a helicopter.

4. Start small quad, Lear to fly. Crash rebuild and learn again. It takes time, don't rush it, you'll just crash more. I know, lost my first quad and crashed my hex 4 times. Second quad has only broken 6 props.

5. See answer to 1.

6. What else... Radio, telemetry, FPV, mission planner, ground station, FAA, AMA, fail safe, flight modes, etc etc.

Good luck and fly safe.
Richard

Replies

T3

Richard Boyhan March 22, 2013 at 11:56am

1. Is big better. Well that's what she asked? LOL. It all depends on what you want to do and how much you want to spend. Small is lighter and cheaper. Bigger is more complex, more expensive and more stable and you might survive an engine failure. You will crash, no matter how hard you try not too. Even the pros eat it from time to time. It's just part of the hobby.

2. Not to up on motors. I usually buy what they offer for my kit. Haven't built a custom copter yet. Have to wait an earn more brownie points before I ask the wife. LOL.

3. Smaller props need to spin faster and larger props can spin slower to get the same lift. Again my 3DR kit recommends 10/4.5 props or the 11 inch can work, with larger motor. Currently I run 850 and the bigger ones are 880. The second number on the prop is the distance where curve comes in on the prop. Props need to be made to spin CCW. So every other motor and prop has to spin CCW. This is to balance the copter and keep it from spinning. Acts like the tail rotor on a helicopter.

4. Start small quad, Lear to fly. Crash rebuild and learn again. It takes time, don't rush it, you'll just crash more. I know, lost my first quad and crashed my hex 4 times. Second quad has only broken 6 props.

5. See answer to 1.

6. What else... Radio, telemetry, FPV, mission planner, ground station, FAA, AMA, fail safe, flight modes, etc etc.

Good luck and fly safe.
Richard

This reply was deleted.