Yellow prop tips on RAF aircraft

[AltcarBoB]

Can anyone tell me when did Yellow propellor tips become standard in the RAF. Googling seems to show it was common but not universal by late war in Britain and Europe. Did it ever become official RAF colour policy or was it a Sqdn thing.

 

Also what was the reason for the yellow tips was it a safety thing I guess a yellow circle would stand out particulary in low light conditions.

[AWFK10]

I believe it was introduced with Expansion Period monoplanes from 1937. It's clearly visible here on K9421, delivered in December 1938. Less clear on K7602, delivered in November 1937, but it's there: you can see how the end of the black propellor blades appears squared off, because the yellow tip has merged into the background. However, I've found several photos of early Blenheim Is where it doesn't appear to be present. Nor is it obvious in a well-known picture of 105 Sqn Battles, which may well have been taken at the time of the squadron's conversion onto the type in August 1937.

 

Others will undoubtedly know more. The primary evidence will be in specifications issued by the RAF to the aircraft industry. But yes, it's a safety measure and not something left up to individual units.

[Troy Smith]

standard all war, 4 inch tip.

38 minutes ago, AltcarBoB said:

Googling seems to show it was common but not universal

universal. Find me an image without.  Note, a certain type of B/W film will render yellow as black.   Otherwise I have never seen prop tips without. standard on US types as well except a few early war exceptions.

 

Safety feature, makes the ends of the blades visible, see below

 

Spitfire patrol    1944. by Etienne du Plessis, on Flickr

[AltcarBoB]

2 hours ago, AWFK10 said:

I believe it was introduced with Expansion Period monoplanes from 1937. It's clearly visible here on K9421, delivered in December 1938. Less clear on K7602, delivered in November 1937, but it's there: you can see how the end of the black propellor blades appears squared off, because the yellow tip has merged into the background. However, I've found several photos of early Blenheim Is where it doesn't appear to be present. Nor is it obvious in a well-known picture of 105 Sqn Battles, which may well have been taken at the time of the squadron's conversion onto the type in August 1937.

 

Others will undoubtedly know more. The primary evidence will be in specifications issued by the RAF to the aircraft industry. But yes, it's a safety measure and not something left up to individual units.

Thanks now I know what I am looking for I can see the yellow tips on the old B/W photos.

[Ed Russell]

There is one exception, at least in RAAF service and presumably RAF too. As they would be useless on an all-yellow aircraft, Tiger Moth for instance, the instructions were to paint them red.

[Work In Progress]

4 hours ago, Ed Russell said:

 and presumably RAF too. 

Nope.

[rossm]

There was a thread here

 

[NorthBayKid]

On 12/18/2019 at 10:03 AM, Troy Smith said:

Note, a certain type of B/W film will render yellow as black

 

It will?  Tell us more.  I've been doing b&w photography and my own darkroom work for 60+ years and I've never seen or heard of such film.  If you mean orthochromatic film, it most assuredly does not render yellow as black.

[Graham Boak]

It assuredly does, as many WW2 pictures show.  It may be that this only occurs with certain filters, or only with those yellows, of which the RAF colour is one, which contain a certain amount of red.  Certainly yellow does not always appear as black on ortho film, but it very often does.

[Troy Smith]

38 minutes ago, NorthBayKid said:

 

It will?  Tell us more.  I've been doing b&w photography and my own darkroom work for 60+ years and I've never seen or heard of such film.  If you mean orthochromatic film, it most assuredly does not render yellow as black.

Tempest VI prototype,  note 'black' outer ring to roundel, 'black'  underside and no yellow prop tips

 

in this image the prop tips appear as a dark tone, but are visible

 

hawker Tempest I

with yellow undersides, outer ring and circle P, for comparison

 

Hurricane IIc  on Malta

note tone of yellow ring, and the darkness of the red compared to the blue

 

 lots more like this  if you look

HTH

[MilneBay]

Yes the perils of orthochromatic film - when I started building model aircraft which was so long ago that the flying machine had only just been invented I used to wonder why Airfix insisted on putting those yellow rings around roundels that in the B/W images available always had a dark ring almost black in colour. Being about 7 or 8 at the time I innocently thought that there were two types of roundels and I really wanted to build one with that dark ring as a change but Airfix never seem to provide those decals.. But then I discovered that there was a thing called orthochromatic film which rendered colours like yellow and red in very dark hues and colours like blue in very light hues. I was extremely disappointed, however I learnt to live with this cruel trick of photography.  😥

 

Good old orthochromatic film fooling modelling acolytes since Pontius was a pilot and Mortis was a rigger.  

Edited December 20, 2019 by MilneBay

[MikeC]

On 12/18/2019 at 5:03 PM, Troy Smith said:

standard on US types as well except a few early war exceptions.

Indeed, there are always exceptions.  With P-39s, for example, some propellers had yellow tips, some didn't: it depended which contractor had built - and therefore painted - the prop.

[cocky05d]

Why were they painted yellow on the rear of the prop,was this for the benefit of the pilot ,maybe to show how fast the prop was spinning .

Sorry ,don't laugh if i am way off target here .

[Graham Boak]

To stop ground crew walking into them from behind.

[Rolls-Royce]

Roger on the "safety" thing. You only get one mistake with props, and it's usually messy. Wonder how many folks the Luftwaffe lost to spinning props, as they didn't paint theirs? 

[thorfinn]

1 hour ago, Rolls-Royce said:

Roger on the "safety" thing. You only get one mistake with props, and it's usually messy. Wonder how many folks the Luftwaffe lost to spinning props, as they didn't paint theirs? 

Funnily enough...though never widespread on ordinary aircraft...one occasionally sees photos of Luftwaffe nightfighters with what looks like white- or grey-painted prop tips. Possibly a field mod, but it would certainly make sense.

[Rolls-Royce]

20 minutes ago, thorfinn said:

Funnily enough...though never widespread on ordinary aircraft...one occasionally sees photos of Luftwaffe nightfighters with what looks like white- or grey-painted prop tips. Possibly a field mod, but it would certainly make sense.

Yeah, at night, that would be a real issue...

[MilneBay]

There's an interesting piece on the use of the orthochromatic and panchromatic type film here -

 

https://filmphotographyproject.com/content/howto/2018/07/panchromatic-orthochromatic-film/

 

It would appear that the early movie makers had the same problems. 

 

I suspect, although I might be wrong, that in the pre-Grouping days in Britain that is why prototype steam locomotives were often fully lined out in the company livery but were painted a basic grey rather than whatever a particular company's overall base livery colour was (green, blue, red, brown, yellow etc.). The reason being that for the as-built photographs of a prototype in the days before reliable colour films were invented, use of orthochromatic stock would often render some particular colours too dark or muddy thus losing the detail required. For instance basic colours in the green/blue area would swamp lighter lining such as white line bordering while conversely the use of warmer hues like reds or browns would swamp darker lining colours. The use of grey would also have the advantage of alerting railway staff of a locomotive still undergoing tests. Just a thought really.   

[JackG]

From what I understand digitally, it's not Orthochromatic film itself that turns yellow to black (though it certainly does darken it).  When used in combination with a blue filter is when the starkest change results.  Here's an example using a plug-in that mimics different film types and various colour filters applied to a modern Hurricane photo:

 

 

 

 

 

regards,

Jack

[fubar57]

That's really cool Jack. Which photo editor are you using

[JackG]

I use Corel Photo-Paint, but the special plug-in to play around with photos is a stand alone product that can be added to most any photo editing software.

 

Download page can be found here:

http://powerretouche.com/black-white_studio.htm

 

Once there,  click  "DOWNLOAD' menu at the top, and then choose whether you want Windows or Apple operating version.   You should create a dedicated folder in the 'plugins' folder of your particular photo editing software for installing.

 

To use once installed, it should be found in the 'EFFECTS' drop down menu, or something similar, and is entitled Power Retouch Demo.

 

 

regards,

Jack

[Rolls-Royce]

Wow. Note what it also did to the camo pattern on the plane and the trees in the background. More subtle than the hit to the yellow, but still a change...

[rossm]

13 hours ago, JackG said:

From what I understand digitally, it's not Orthochromatic film itself that turns yellow to black (though it certainly does darken it).  When used in combination with a blue filter is when the starkest change results.  Here's an example using a plug-in that mimics different film types and various colour filters applied to a modern Hurricane photo:

 

regards,

Jack

I'm not sure why you would use a blue filter with ortho film? It doesn't immediately make sense to me as a photograper.

 

My understanding is the earliest films were most sensitive to blue, then came orthochromatic which extends sensitivity into greens and finally panchromatic which covers yellows and reds. Even within those broad categories the response is not smooth but has peaks and troughs at different wavelengths. A general example can be found here https://www.researchgate.net/figure/Spectral-response-curves-for-three-types-of-film-with-different-spectral-sensitivities_fig3_2578016

 

Having learnt photography in the days of panchromatic black and white film I would use a yellow, orange or red filter to darken blue skies and bring out clouds and green to lighten foliage. Blue was really for balancing daylight colour film to tungsten lighting, I don't remember it for black and white.

 

Ansel Adams used to use what he called a "minus blue" filter, a Wratten No12 IIRC which was a deep orange, for a lot of his black and white landscape shots and I believe this was a fairly standard practice although the exact choice of colour was down to the individual photographers preference and I remember plenty of references to red being used.

 

Remember the rainbow - Violet, Indigo, Blue, Green, Yellow, Orange, Red - in the order of increasing wavelength so any film that renders yellow as black will do the same to orange and red (and darken brown which has a strong red component).

[JackG]

Hello Rossm, personally I would not know why a blue filter would be used, only that this particular filter when applied, gives the results that mimic what sometimes is seen in WW2 RAF photos.

 

If I had to guess (and basing that on googling the internet), it would be just like you mentioned - some of the b/w film back then was quite sensitive to blue.  In order to compensate for this, the added blue filter washes out the sky and makes  the foreground subject (in this case an aircraft) nicely stand out.  Could be the war photographer did not know how well the Orthochromatic film had improved and wanted to try a few shots with a blue filter.   Or maybe he was aware and was fond of the effect?   Whichever the case, it's not something that was mainstream, as we only find the odd photo examples here and there.

 

regards,

Jack

[skyscooter]

Hi,

I van answer this for you as I have 1st hand experience of this.

I'm a licenced aircraft engin

On 12/23/2019 at 9:16 AM, JackG said:

Hello Rossm, personally I would not know why a blue filter would be used, only that this particular filter when applied, gives the results that mimic what sometimes is seen in WW2 RAF photos.

 

If I had to guess (and basing that on googling the internet), it would be just like you mentioned - some of the b/w film back then was quite sensitive to blue.  In order to compensate for this, the added blue filter washes out the sky and makes  the foreground subject (in this case an aircraft) nicely stand out.  Could be the war photographer did not know how well the Orthochromatic film had improved and wanted to try a few shots with a blue filter.   Or maybe he was aware and was fond of the effect?   Whichever the case, it's not something that was mainstream, as we only find the odd photo examples here and there.

 

regards,

Jack

Hi,

I can answer your question, I'm a licenced aircraft engineer with 52 years experience.

 

The yellow prop tips were originally introduced in the 1920's, originally props were wood and generally left varnished wood colour,, but as aircraft developed and performance improved, particularly  with regard to endurance, propellers began to become a problem especially when the sun was behind the aircraft or at an angle where the sun reflected off the propeller surfaces dazzling the pilot or obscuring the pilot's vision.

 

Propellers started to be painted matt black, this had the effect of rendering the propeller almost invisible when rotating.

For obvious reasons this became a critical hazard to those around the aircraft when on the ground, in particular when starting. With experimentation by the propeller manufacturers it was found that yellow tips were most effective in highlighting the extent of the propeller's disc and this was standardised by US, UK & Italian manufacturers

 

In Germany, the preferred method was to paint pattern on the propeller spinner which highlighted the propeller was turning, and is very effective in doing so (incidentally this is still used to this day where a spiral is painted on the nose cone of turbofan engines).

Whilst this is very effective, it does not define the propeller's disc, but the argument is that if the engine is running everyone should be keeping a very healthy distance which I would have to agree with.

 

In the early 1970's the RAF introduced stroboscopic propeller blades(still with yellow tips) but this never caught on outside the RAF.

 

Some propeller manufacturers introduced red & white striped propeller tips, this was as effective as the yellow tips but never replaced them and had the added inconvenience of limiting individual propeller blade changes as red & white striped & yellow tipped propeller blades shouldn't be mixed on the same propeller for obvious reasons although I have seen it done and had to fix it.

 

I hope this helps.