Coning angle and does the camera lie ?

[Hughes500]

www.ahhelicopters.co.uk/drop

Picture taken a couple of weeks ago, hope the blades weren't doing this !


Might get the pix here this time



Got one of them for you. http://www.ahhelicopters.co.uk/photos/Lifting_spares_small.JPG

[Blue Rotor Ronin]

Hope your blades are a tad more visible than your piccies.... will check again later as it sounds fairly fascinating.:ok:

[Ascend Charlie]

The one on the bottom doesn't appear to have a coning problem...

The one on the top is the result of a typical photo from a focal-plane shutter. As the shutter opening moves from right to left across the film, the blades have time to turn and appear bent. Confirm this with the tail rotor (looks like a boomerang) and the blade on the far side of the tailboom, with only the tip painting on the film and looking like it doesn't belong to the aircraft.

There was a beauty on another thread of a tiny old (1940s) chopper and the shutter made it appear that the two-bladed rotor system had both blades on the same side of the mast.

[MightyGem]

This is what the top picture should show. It does look quite alarming
http://www.ahhelicopters.co.uk/drop

[Blue Rotor Ronin]

Er yeah.....what Charlie said..cool pic, is that what cutbacks are and what do the pax think...:ok:

[Lu Zuckerman]

To: Mighty Gem

As previously stated the blades appear to be coning upward at a radical angle however it is a result of what the camera sees and when it sees it. Please note the blade cuffs. They are pointing outward due to centrifugal force (where’s NickLappos). The blades are attached to the rotor head by strap packs which are very flexible so if the blades were coning as indicated the blade cuffs and the strap packs would be flexing upward with the blades.

:ok:

[PPRUNE FAN#1]

Blimey! Thought somebody caught a pic of my last auto!

...Or was it my last steep approach?

[MightyGem]

Having thought about it, I've taken many a photo using a focal plane shutter(standard SLR camera) and never seen this effect before. :confused:

[Lu Zuckerman]

To: Mighty Gem

Please note the tail rotor. Each blade seems to be bent downward. Also note over the tail cone there appears to be another blade. These distortions are a function of lens setting and speed of the shutter and the rotational velocity of the main and tail rotor.

:cool:

[helmet fire]

:8 :8

They are pointing outward due to centrifugal force

Guess you just cannot teach an old dawg new tricks!!;) ;)

:ok:

[McSkull]

I can't stop laughing at that picture!!!
I suppose the faster moving outer portion of each blade contributes more to the affect.

McSkull:D

[Lu Zuckerman]

To: helmet fire

Would you rather I said "note the blade cuffs as they are pointing inward due to centripetal force".

:ok:

[Cyclic Hotline]

This type of distortion is very common in old helicopter photo's and were the result of rotary bladed type shutters, coupled with the generally slower films and exposures in use, back in the dark ages.

As Mighty Gem pointed out, this type of distortion does not occur with "normal" curtain type shutters which describe the system in use by the vast majority of film camera's still in use today.

What did they take those pictures with?

And yes, even film can lie. Let's not get into digital imaging!


:}

[Hughes500]

The pix were taken with a digital camera. I think the effect is to do with it being digital. Ever tried taking a photo of a car going past - you always miss it - you have to take a lead on the subject;)

[Vfrpilotpb]

Whenever I take piccies of Helicopters, you cannot tell what keeps them up, for they always seem to have a great big spar type thingy above the cabin and the same only smaller at the back end, still I suppose I could always ask Mrs Vfr to press the button, mostly use 200/400 speed films and this tends to catch most fastish types of anything in motion, without much distortion.

Caught a cricket ball entering a fielders hand, and a golf ball leaving a club head, but I am unable to catch a bat in flight, any one know how to?:8
Vfr

[helmet fire]

vfr: having caught too many bats in flight, I have found that the easiest way is with a rotor blade at greater than 80 KIAS on NVG!!
:} :} :}

[Cyclic Hotline]

Well, I've taken a ton of digital pictures of helicopters, and never had the effect seen here, they look just like pictures shot on film! :)

What kind of camera was it?

I think the easiest way to catch a bat in flight pb, is with a net! ;)

[MightyGem]

Strange, if you look through their website there are only two pictures showing that effect. I imagine that they must all have been taken with the same type of camera. :confused: