The Yellow Blob

[Guest]

Building, or trying to, a Lancaster.

Every time I look at the thing (really is a beautiful looking monster of an aircraft) I see this yellow blob on the pilot's seat. It bugs me.

So what is that yellow blob for. Is it just paint, does it have a use. It is hidden when the pilot sits on his seat. Do all bombers have this yellow blob ?

Any ideas? I just like to know the reasons for everything. This can be a bit of a nuisance at times !

Laurie

[Guest]

To quote a reference source

"The Dot

Wags have joked that the yellow circle on the pilot's seat of the Avro Lancaster gave German pilots something to aim for—seemingly very sporting of the English, but not true. The paint had a practical purpose. The odd-colored orb contained pigment sensitive to poison gas. When a crewman saw a shade other than bright yellow, there was big trouble. And this warning was not only for gas that might potentially be used by the Germans. The UK was fully prepared to employ its own stockpiles of poison should Hitler have chosen to go down that dark path. Planes like the Lancaster would be the delivery system to enemy cities or military strongpoints. During a botched drop, it was quite possible for unlucky flyers to expose themselves to their own toxicant."

Seems feasible

[Guest]

Hey thanks for that CDW. That is fascinating. As the saying goes.

Not many people know that !

Laurie

[Guest]

Top marks Colin. I definatly didnt know that and can now answer the question with pride if im ever asked. Nice piece of historic info.

Cheers

Andy

[Guest]

Chucked in yellow dot in search & these came up. Amazing that no one can say catergorically that there speculation is correct as it does seem all speculation.

Now where have I heard of this phenomenon(amazing spelling correct first time) before. Could it be Lysander colours ?

Laurie

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Yellow circle on back of Lanc Pilot seat

The Lancaster Archive is particularly interesting.

[Guest]

Did a bit more digging and the most logical reason for the Gas theory was ....

The "blob" was painted on the back of the pilots seat so the rest of the crew could see if there was a risk of the pilot being affected, the pilot wouldn't be feeling the need to concentrate on a patch of paint as he was so involved with flying the plane and watching out for other issues whilst in the air.

The idea of weight that one of the links put forward is a bit thin as words like "heavy item" and/or putting the actual weight on the item would have been simpler.

Also one link seems to indicate the gas paint was on the outside of the aircraft? ... would this not be a bit of a waste of time as the plane would be flying through "thinned down" areas of it, gas only really has influencing abilities in confined areas where the required gas/air percentage of toxification would be achieved?

If this theory were to be related to one we know then all the germans within range would have dropped to the floor when the doors to the gas-chambers were opened and the gas was released into the atmosphere.

[Guest]

Sorry, but that's not true, especially as you can find examples of armour with the circle on both sides. By the time the paint had had time to react, the crew would have been dead anyway, since the gas was heavier than air, and rolled along the ground. The early war outside patches, within easy sight of pilot or a gunner, were a sharp warning of phosgene, and to abort the landing and go elsewhere. Some late war gasses, which created the greatest fear, were formed by airbursts, and fell to earth as droplets, which burned the skin, and did other nasties. Removal had to be done by high-pressure hoses, with the mixture soaked up by cloths and disposed.

Even authors of books on the Lancaster don't know its purpose, but my pet theory is that it was a warning, but not for gas. On the Spitfire, 11-11-40, a modification was introduced "To paint yellow markings on magnetic armour plate"; it was cancelled 20-11-40, possibly because it was realised that the armour was too far away to have any effect. On the Lancaster, the navigator sat immediately behind the pilot, and one of his tools was a hand-held "Observer's" compass; if he went to take a reading, and remained too close to the pilot's armour, its magnetic pull could cause a simple misreading by several degrees.

Edgar

[Guest]

Having had a number of boats & the compass in each swung once a year that is it. Then unless there is an alteration or addition which will effect the compass then all is well unless some one puts something next to the compass by accident such as even a penknife. So the presence of the metal protective armour would be accounted for during the swinging of the compass. The question is why bring attention to it in this manner when it does not seem to require it.

As far as hand held magnetic compass is concerned not sure how they got on, if they did use one, as it will be correct when manufactured. On a boat you would take readings as far away from any metal as possible which you cannot do in an aircraft as you are surrounded by a great deal of it with a magnetic potential. In the dark I would have thought it impossible to take readings on the ground from a known source to give an accurate fix.This especially as the Germans tended to switch off all their lights. If you knew the source you were pointing at you would know where you were in terms of the accuracy of those days.

However I do believe they used Astro Compasses which did not reply on magnetism & took fixes on the stars so that would seems to discount the yellow blob theory, I think.

Laurie

[AlanG]

Some late war gasses, which created the greatest fear, were formed by airbursts, and fell to earth as droplets, which burned the skin, and did other nasties. Removal had to be done by high-pressure hoses, with the mixture soaked up by cloths and disposed.

The modern name being 'Blister agents'

Blot, bang, rub as required lol

[stona]

I've heard all these "explanations" before. I never liked the gas one for the reasons stated above. I liked the idea of it indicating which side of the armour was hardened,until I saw evidence of the marking on both sides. The compass interference explanation seems interesting but I don't know anything about compasses in the aeronautical field.

You pays your money and you takes your pick.

Cheers

Steve

[Guest]

Quote. " It should be on one side only. The reason is that the armour plate was 'softer' on on side. The intention being to slow any projectile hitting it down enough so that when it reached the 'hard' side, it would be slow enough to prevent penetration. The yellow dot was on the 'hard' side, I.E. the side with a body next to it "

This seems feasible it fits the boxes (!?!). Suspect that the fitting both sides may have been the pilots idea, double protection. Especially if this is the answer fitting it both sides would have had the back one around the wrong way. IE the pilot not realising the significance of the yellow marking.

Laurie

[stona]

The head armour was a 3/8" thick steel plate. How one side was hardened I'll leave to a metallurgist to reveal. It was not demagnetised so a compass swing would have been done once it was fitted just as would be done when any extra equipment was added.

By the way,my dad was a FAA pilot and doing a compass swing was a chore he hated. I've never understood why the pilot had to be involved. Did they have to do some kind of test flight once the swing was completed?Sadly he is now gone and I never bothered to ask him.

Cheers

Steve

[Guest]

Your father being there as pilot gives a clue Steve.

On a boat compass swing the Compass Adjuster will take a reading on points adjust on that point then ask for the boat to be swung around to a compass point he gives you. This carries on until he has adjusted the magnets so they give a an as accurate as possible reading. He then gives a card with adjustments to be made on a particular heading. Usually o, 1 or -1 degree depending on the complexity of the compass swing.

With an aircraft I assume he would have needed your father to swing the aircraft to each point. I have read somewhere along the line that they used trollies under the wheels but that may have been at the factory. A test flight would not have been needed

Bizzare but the Compass Adjuster who came over to Jersey for about 15 boats adjusted my little 33 foot boat then went home & adjusted the QE2. How he did that I do not know as you did not swing the QE2. Neither was he nautically dressed. Leather shoes, o my deck, & suit.

Laurie

[Guest]

This got me quite interested and my tenacious side rose to try and find "the answer"

Loads of bumf floating the t'interweb about gas paint and armour and compasses ..

but i found this....to do with armour .... apparently endorsed by ex lancaster aircrew

"It is simply a quick visual check item to ensure that the armor was in the up position before take-off,i.e,if the circle wasn't seen the pilot would be rapidly signalled to put it into the up position.

We discussed this on the Lancaster Archive forum some months ago and that was the answer given by a couple of ex-wartime Lanc aircrew.

They agreed that the pilot had such armor because he was the last person on board that anyone wanted to be injured.

Although the F/E or Nav could well be capable of flying the aircraft to a reasonable degree,the pilot was the man to fly them home and pull off a safe landing."

[Guest]

As far as hand held magnetic compass is concerned not sure how they got on, if they did use one, as it will be correct when manufactured.Laurie

The compass was known as "O2A Observer's Compass," and had a torch bulb, in the wooden handle/base, which illuminated the "innards" from below through a ground-glass screen. That was the "astro compass," which was supposed to be used from the astrodome, taking fixes from stars (whose lights the Germans couldn't switch off,) and had an accuracy of +/- 1 degree; if you get the impression that I've worked on/repaired them you'd be right, and I can assure you that they relied on a pair of bar magnets.

Even a pair of steel-framed glasses will pull them off as much as 5 degrees, and you'll find much the same with modern standby compasses; even their bulbs have to be made of brass, so as not to have any effect. One girl, who came to work at our firm, could not, try as she might, get sensible readings from any compasses; we were totally baffled, until, during a chat (not hands-on experience, sadly) it transpired that she wore a heavily-wired bra, and, as soon as she changed to an elasticated sports type, everything was fine.

Aircraft compasses are swung far more often than once a year, in fact it's normal to do a swing before every flight, and it would be a simple matter to check the O2A from the astrodome at the same time.

"Landing" compasses, which are kept on the airfield, and against which the a/c compasses are checked, have an accuracy of +/- half a degree, and have to be checked annually, and repaired if necessary.

Edgar

P.S. Having checked on files, regarding armour, in the National Archives, at least until 1943 the RAF never used hardened-on-one-side armour, it was simply armour plate.