maths/blade tip speed question

[AcidDrink]

Kinetic energy of flying blade very quickly fades away with distance, in other words don't fly too close to yourself.

[tonystevens]

so would an ejected blade fly straight like an arrow or would it flat spin??

[Rotorhead]

Probably flat spin out and flutter down after it got rid of most of its speed.

[Steve]

large surface area and relatively low mass - would slow down pretty quickly by wind resistance. Also it wouldn't slice through the air like an arrow, it would tumble and spin randomly.

[nicobec]

Considering that the tip is going to be the first part of the blade to hit you if you fly into yourself or someone else, 400mph and up is nothing to underestimate, at that sort of speed they dont need to have a sharp edge......

But think if they did.

[Cagey]

large surface area and relatively low mass - would slow down pretty quickly by wind resistance. Also it wouldn't slice through the air like an arrow, it would tumble and spin randomly.

I'm glad you said that,was beginning to think of body armour there for a while.

[barney]

I experienced a main blade depart on a 90 and its similiar to a gun going off. The airframe will be likely be totalled before it hits the ground due to the imbalance. The loose blade can travel a considerable distance and certainly capable of decapitation at 30m and travelling a 100m.

[Steve]

I experienced a main blade depart on a 90 and its similiar to a gun going off. The airframe will be likely be totalled before it hits the ground due to the imbalance. The loose blade can travel a considerable distance and certainly capable of decapitation at 30m and travelling a 100m.

Experience talks wonders. Kind of puts all the theory to shame. Thanks.

[trillian]

This is one of those things that's fun to think about sometimes. When you go full scale the rpms come down
but the distance travelled goes up massively. On a UH-1 for example the headspeed is only 290 rpm but
because the rotor span is something like 58 feet, the advancing tip can break the sound barrier in forward
flight!

I remember reading something a few years ago that the blades of a 50 size heli will be exerting a force
of something like 200 pounds due to centrifugal force.

I've seen a blade fail on a 450 Sport where it pulled apart at the root and the main shaft was bent
at almost a 45 degree angle. It looked like someone had just put it in a vice and pulled it right over
from above the bearing block.

[Steve]

This is one of those things that's fun to think about sometimes. When you go full scale the rpms come down
but the distance travelled goes up massively. On a UH-1 for example the headspeed is only 290 rpm but
because the rotor span is something like 58 feet, the advancing tip can break the sound barrier in forward
flight!

I remember reading something a few years ago that the blades of a 50 size heli will be exerting a force
of something like 200 pounds due to centrifugal force.

Your Huey blade tip speed is almost bang on 600 mph with the figures you quoted.

[barney]

When the model exploded bits went all-ways in an instant. Mainshaft bent in flight, and it went super Piro flinging the boom out etc..we never did find the lipo as it got batted off the radio tray even though the field was 1" grass and huge. One main blade was buried its chords full depth and span to the trailing edge 30m away from the model.... err was just a few mtrs in front of me! Worse still you didnt even see it. Even some of the radio was knackered due to the severity of the imbalance.

[arby]

Also it wouldn't slice through the air like an arrow,.

Oh yes it would, I had the pleasure of kneeling down to check someones tracking when the wooden blade gave way at the root, it travelled like an arrow over my head and landed some twenty feet behind me.