Comments on: CAN SOMEONE EXPLAIN THIS?

By: David Malone

David Malone — Mon, 21 Apr 2008 20:21:19 +0000

I guess it is an optical illusion too, probably caused by the photo not actually being a moment in time, but being scanned in some way from the CCD in the digital camera and at the same time the blades were moving. It would be similar to the sort of weird pictures you used to get if you photographed or filmed a CRT TV, where you get artefacts because of the refresh rate of the TV (which you can’t usually see because the persistence of images on the eye is quite long).

[I believe that one of the first things that radiologists have to learn is spot artefacts that caused by different types of imaging.]

By: Mike - the pilot

Mike - the pilot — Sun, 13 Apr 2008 23:39:41 +0000

Believe it or not, I’m the pilot flying the aircraft. While the blades to cone as mentioned earlier, I don’t this they cone that much. I believ that it is some kind of visual illusion based on the fact that the EC135 (that is the helicopter model are looking at) only has 4 main rotor blades, not the six shown here. This aircraft’s rotor system is a hingless rotor system therefore flapping is not involve. Sikorsky mounted a camera on the hub to show what the blades acutally do during flight, The story goes that when the actually looked at the film they decided that pilots probably didn’t want to know that the blades acted like a piece of speghetti or so goes the story.

By: Michael - Lover of Amy

Michael - Lover of Amy — Fri, 11 Apr 2008 11:29:57 +0000

I’m sure some tech or aero guy can explain it. I simply think it’s an AWESOME picture, makes me jealous just seeing it.

By: Dawn @ Coming to a Nursery Near You

Dawn @ Coming to a Nursery Near You — Thu, 10 Apr 2008 19:32:53 +0000

Ok, that’s just freaky!

By: Suzanne

Suzanne — Thu, 10 Apr 2008 17:14:27 +0000

I believe what you are seeing may be a combination of “coning” which is the upward deflection (bending) of the blades during takeoff and “flapping” where the blades angle upward from a hinge at the center of the rotor. I’m not a rotorhead (helicopter person), the aircraft I work on have fixed wings so I can’t tell you how much of a deflection is normal, or what the maximum is. But wow, it looks impressive doesn’t it? The visual effect is probably exaggerated by the relative length of the blades….I’m guessing they are longer than they appear in the photo. Perhaps Mike can weasel himself a chat with the pilots? Most pilots love to talk about their aircraft, and it would be an interesting chat if he’s as much of a nerd as I am!

By: Mary T

Mary T — Thu, 10 Apr 2008 15:27:44 +0000

I have heard of that happening. Same reason that when you approach the helicopter when the blades are going you’re supposed to duck. They are so flexible that even though one would think you’d never be tall enough, ducking is advised. Of course, that’s just hearsay - I’m not a helicopter expert so don’t quote me!

By: Janet

Janet — Thu, 10 Apr 2008 13:59:51 +0000

weird!!!

By: Karen M

Karen M — Thu, 10 Apr 2008 13:14:01 +0000

I guess this is just trick to the eye, sort of like the “rubber pencil” trick.

But what does I know? I ain’t no rocket scientific genius (read with laid back southern drawl and twang)HEE HEE HEE

By: Awesome Mom

Awesome Mom — Thu, 10 Apr 2008 04:14:48 +0000

That is freaky!

By: Lynn

Lynn — Wed, 09 Apr 2008 22:39:44 +0000

The rotors are quite flexible but I think that picture is an illusion.

By: Fran

Fran — Wed, 09 Apr 2008 20:46:13 +0000

My goodness that looks so strange! I can’t explain it but I do hope someone can so I can learn why the rotors look like that. In the picture just before this one they look straight. Maybe it’s some optical illusion that is common knowledge (except for a few of us!). IS THIS ONE OF YOUR KOOKY JOKES OR SOME KIND OF TRICK QUESTION, KAREN?

By: Christy

Christy — Wed, 09 Apr 2008 20:42:04 +0000

Hmm. I’ve never seen that happen.