Weight of an R44 Main Rotor Blade

[Gimini_pilot]

Dear All,

Just new on this forum platform.
Hope this questions is posted correctly, and finds it answer well?

Does anybody by any chance know what the exact weight is of a Robinson R44 main rotor blade? Just one blade.

Thanks in advance for your reply.
:)

[feathering tickles]

Does the answer vary with RRPM?

[ascj]

Going off the accident reports id have to say the weight is 'too light' especially when left with just one!!😁

Waiting for incoming

[gulliBell]

I was going to say, about the weight of a real helicopter tail rotor blade. But as the OP is new to the forum, I'll just say welcome aboard.

[I16]

Sorry if this is old news.


https://www.stuff.co.nz/southland-times/news/100686212/Helicopter-emergency-prompts-redesign

[Spunk]

To sum it up:
As long as you stay within the limits and use the aircraft for what it was designed to be used...than the R44 is good to go. If you use it beyond that than you better check twice.

[n5296s]

> Does the answer vary with RRPM?
Of course. m = m0 / sqrt(1 - v^2/c^2) and all that Einstein stuff.

A more important question: is this an African rotor blade or a European rotor blade?

[Hughesy]

Before or after it becomes detached? :E

[evil7]

@ n5296s

I wonder if you would care to explain to me how a rotor blade will change “its weight” with rpm?
I could swear that the “weight of the blade” would stay the same at any rpm😉
Only nitpicking here🤓

[jtt]

I wonder if you would care to explain to me how a rotor blade will change “its weight” with rpm?

It's a joke - according to the (special) theory of relativity the mass of an object increases with it's speed - the nearer it gets to the speed of light the heavier it becomes, so it takes more and more energy to accelerate it even nearer to the speed of light. And since the mass goes up to infinity at the speed of light py would need an infinite amount of energy to reach it. That's why no object with mass can reach the speed of light (in contrast to photons which have no mass - but then they can't slow down;-)

While, theoretically, the mass of the blade increases with RPM, this is completely irrelevant though. Even if the tips would move a the speed of sound (which is about a hundredthousand times slower than that of light) the effect would be umeasurable (heavier by factor in the order of 5*10^-11, and even less for the bits of the blade nearer to the hub which move slower) - if you hit a bug and one of it's whiskers sticks to the rotor that effect would be quite a bit larger.

[feathering tickles]

Evil7, do you understand the difference between weight & mass?

[n5296s]

@jtt - quite so. By my quick math it's 1/10th - 1/100th of the weight of a fly's leg. Probably not worth worrying about too much.

I confess to not being too well up on general relativity, but iirc weight (i.e. the force produced by gravity) will increase directly with relativistic mass, so it will affect the weight in the same way it affects mass.

I can't for the life of me imagine any OTHER reason why rotor mass/weight would depend on RRPM. The blade will stretch a little, which will affect its moment of inertia (not by enough to get excited about), but not its weight.