We have an Octo Copter with Turnigy 810 kv motors. We got composite props which we thought would be fine. It went up in the air and one broke from what we think was a stress fracture.We have now…Continue
"Presumably, propeller manufacturers do not test their products for RPM tolerance in a vacuum. If there is air present, then aerodynamic forces exert themselves upon the blades in a manner consistent with the laws of physics, which are well…"
"Brad we seem to have a difference in opinion on the stresses put on a horizontal versus vertically mounted propeller. No problem.
However, I need to point out that I am not accusing anybody of anything. I simply point out that rpm…"
"Karla, you may have missed this because the thread with Mr. Chan sorta ran off the rails.
Whomever told you that "normal props" are not meant for quads is wrong. A prop doesn't "care" what it's used for, it only…"
"Graham, you're spot on. They would never quote a maximum weight because it's an irrelevant number. They might quote a maximum thrust, however, at a given RPM, but that too might be meaningless, because the thrust will change…"
"P.S. Chris graduated from George Washington, not Georgetown (my mistake).
P.S.S. The APC Slow Flyer series props are made for very light aircraft applications. If you examine the root of the blades (near the hub), they are obviously far less…"
I thought about asking you to take this to PM, but I cannot let this position of yours stand unchallenged.
The minute I saw your diagram I thoroughly understood your erroneous assertion with the greatest of clarity.
A given propeller…"
"Brad, I thought you had understood the point of the diagram. I guess not.
Basically, there's no understanding of Netwon's law, here. In order for a multirotor to hover, the prop has to provide enough thrust to negate the force…"
"Methinks this issue needs a bit of further discussion, as the diagram you show illustrates a fundamental misunderstanding of Newton's Third Law. Just to clarify, forces are described as vectors, and the only two attributes of a vector…"
"They're not, but that's an aerodynamic thing. Consider this: how fragile do the roots of helicopter blades look in comparison to airplane propellers? It could very well be that in multicopter applications, the RPM limits may be…"
"It helps me understand that I must respectfully stand diametrically opposed to your assertion. The propeller can never have more force upon it (other than its own mass, of course) than it, itself, can generate in aerodynamic thrust."
"One way to test how much actual weight a prop can handle is to hang weights off it and see what the breaking point is. Multiply that by about 8 for your Octo, since the weight is distributed over 8 props."