# does thrust equal weight lift capabilities?

ok, so I am interested in building a 1 person quadcopter, kinda like a quadcopter/street bike if that makes any sense. i have a found a motor/prop combo that produces 170lbs of thrust that only ways 54lbs. simple math says that there should be a spare 116lbs that can be used per motor. but this is where I feel like I am missing something simple.   my math says that with four of these motors it should be able to lift 464lbs -200lbs person = 264lbs so a 200lbs vehicle body including all the computers, chassis, wires... should be within reason with a spare 64lbs of thrust remaining. plz let me know where i feel like i have gone wrong. i can provide better specs of the motor prop combo if that would help clarify my question. i can also provide a 3d mockup of what i have planned if that would also help clarify.

thank you

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Toga_Dan4 months ago

ive seen people fly with power from extension cords. this saves weight on the vehicle. do you intend to carry batteries? or fly tethered by a power cord?how much do the batteries weigh?

4 months ago

I built a haver craft once powered by a shop vac. Worked great but the teather was a serious handicap.

Jack A Lopez4 months ago

The word for it is, "force"

https://en.wikipedia.org/wiki/Force

Both weight and thrust are examples of forces, and they are measured in the same units, e.g. newtons (N) or pounds force (lb force?)

What else can I say about forces? Well, forces are vectors. So they add like vectors. Direction matters. If I were to draw the most simple free body diagram

https://en.wikipedia.org/wiki/Free_body_diagram

for your flying machine, I guess I would draw four arrows pointing up, each with a magnitude of 170 pounds force. Then, connected to the center of mass of your contraption, I would draw one arrow pointing straight down, and the magnitude of that arrrow would be the same as the weight of all the components of the flying machine, including the driver.

Anyway, in this simplified free body diagram, for which all the thrust pulls straight up, and all the weight pulls straight down, it is like you already calculated. Essentially just arithmetic. More force pulling up than force pulling down, means the net force pulling up is positive.

So I think you did the math right.

Regarding English grammar, writing "ways" in place of "weighs" is using a homophone incorrectly.

https://en.wikipedia.org/wiki/Homophone

Although, I have to admit, I don't see "ways" and "weighs" confused very often. The most commonly misused English homophones, are of course, {your, you're} and {there, their, they're}.

By the way, in your list of weighty things, you did not explicitly mention fuel, or batteries, or whatever you are using for energy. The weight of the fuel is usually an important consideration for flying machines.

4 months ago

regarding homophones colonmaybe he was using speech to text, as I currently am. not necessarily a smart computer, but useful. mine recently substituted Buy 4 by. ha.and I see that my device just substituted the number 4 for the word for. I ain't fixing it.

4 months ago

Oh man! First spellcheck! Now speech-to-text! The English language is doomed, I tell ya! Doomed!

This talk about homophones reminds me: the best thing about "OU812" was the clever title.

https://en.wikipedia.org/wiki/Van_Halen_discograph...

Really, you have to go back to "1984", to find a Van Halen album with some good songs on it.

rickharris4 months ago

You mean like this?

or this?

You realise you technically are very limited in where you can use such a thing.

Assuming the spec is correct then your right, thrust more or less = lift power HOWEVER you don't want to be running flat out to lift you need some overhead. Lift at ground level is easier then higher up (ground effect).

Falling from any height especially when props are about is almost always fatle.

4 months ago

, Colin furze. I don't know if he is lucky, or just that skilled. no helmet no goggles no protective equipment at all. and that necktie. LOL

4 months ago

I suspect he takes somewhat more care than the youtube suggests, he presents his channel as entertainment - and is very successful at it - .

He actually lives about 3 miles for me. not that I know him.

iceng4 months ago

These are light enough to have a parachute save me and machine.

rickharris4 months ago