Mistakes in Aviation

HoHun · 05-03-2008, 06:36 PM

Hi Evan,

>The Junkers J1 was made mostly of duraluminum, not stainless steel.

Steel is correct for the J 1 of 1915 vintage. It took Junkers about two years to come up with an all-metal light alloy aircraft, and I'm sure you are thinking of the Junkers J-I - the former was the Junkers-internal designation, and the latter was the Fliegertruppen designation in which the "J" did not stand for "Junkers", but for "Infanterieflugzeug" (ground attack plane - "J" was habitually substituted for an initial "I" in German typesetting tradition). According to the Junkers count, the J-I was the J 4, but it was a completely different aircraft from the J 1. You're right that it was mostly a duraluminium aircraft, it was only the armour tub for engine and crew that was from steel.

Velius posted a short description of the type (complete with photograph) here:

http://www.ww2aircraft.net/forum/avi...sts-13099.html (Aircraft-Technological Firsts)

Though I'm not a Wikipedia fan, here the link to the article on the J 1:

Junkers J 1 - Wikipedia, the free encyclopedia

Here the article on the J.I - the picture is interesting as it highlights the completely different layout compared to the J 1:

Junkers J.I - Wikipedia, the free encyclopedia

The J 1 due to its prototype nature is not a well known type, but was quite a milestone in aviation - it even hat a jet radiator with diffusor and jet nozzle to exploit what was later termed the "Meredith effect".

Regards,

Henning (HoHun)

Graeme · 05-03-2008, 07:12 PM

Hi HoHun.

My understanding is that the Junkers J1 (aka the "Tin Donkey") was made with sheet iron over an iron tube framework. No aluminium.

From the site you posted...

"Junkers had to use sheets of heavier electrical steel instead for his first all-metal aircraft designs, similar to the types of ferrous sheet metals used in laminated-core AC electrical transformers".

Turner and Nowarra in their book "Junkers" state that at the time aluminium was so "precious", that he could not acquire any for his project and that many thought the all-metal design as "frivolous".

(edited. Apologies, re-read your post, this is actually your point. J1 confusion!)

pbfoot · 05-03-2008, 08:04 PM

I know that in the early 1900's aluminium was a rare metal I've heard it was up to several hundred dollars a pound .One of the reasons being that few places had the electric power able to supply large quantities for the refining/smelting of Aluminium.

evangilder · 05-03-2008, 08:41 PM

Good catch Henning. I misread that same Wikipedia article, and swore I read that it was made of duraluminum. After re-reading, I see that is not the case.

FLYBOYJ · 05-03-2008, 11:56 PM

Yes indeed, but remember, we were talking about stainless steel, a little different animal.

HoHun · 05-04-2008, 05:29 AM

Hi Flyboyj,

>Yes indeed, but remember, we were talking about stainless steel, a little different animal.

Seems you're right ... I had assumed the J 1 was from stainless steel, but "electrical steel" appears to be something else!

Regards,

Henning (HoHun)

Graeme · 05-04-2008, 05:45 AM

Quote:

Originally Posted by FLYBOYJ

we were talking about stainless steel, a little different animal.

Joe, you strike me as a knowledgeable man on many matters, including aviation metallurgy.
My eldest brother is a metallurgist (with Alcoa in Moscow) and he once told me that 'pure' stainless steel is non-magnetic. I don't know what he meant by pure, but I'm guessing that there are many grades of stainless steel. I've tried a magnet on artery forceps and other surgical stainless steel, and it sticks hard, but no adherence to stainless steel plumbing fixtures.

Why don't magnets work on some stainless steels?: Scientific American

I remember reading that the Bristol 188 and XB-70 were of stainless steel construction and required new welding techniques. Is this because there's no ferrous content in the stainless steel used in aviation? Apart from heat and water resistance, what other advantages would stainless steel have in aviation? Would the Valkyrie have been magnetic?

Now this is way off track, but I have to ask, (and may regret it) what's meant by "If it's red or dusty, don't touch it!" above your siggy? I've been meaning to ask you for some time now and have always assumed that it's related to OH&S in the aircraft maintenance industry?

But after watching this film...

...there could be a completely non-aviation meaning to "don't touch the red dust"...

FLYBOYJ · 05-04-2008, 07:37 AM

Quote:

Originally Posted by Graeme

Joe, you strike me as a knowledgeable man on many matters, including aviation metallurgy.
My eldest brother is a metallurgist (with Alcoa in Moscow) and he once told me that 'pure' stainless steel is non-magnetic. I don't know what he meant by pure, but I'm guessing that there are many grades of stainless steel. I've tried a magnet on artery forceps and other surgical stainless steel, and it sticks hard, but no adherence to stainless steel plumbing fixtures.

Why don't magnets work on some stainless steels?: Scientific American

I remember reading that the Bristol 188 and XB-70 were of stainless steel construction and required new welding techniques. Is this because there's no ferrous content in the stainless steel used in aviation? Apart from heat and water resistance, what other advantages would stainless steel have in aviation? Would the Valkyrie have been magnetic?

Now this is way off track, but I have to ask, (and may regret it) what's meant by "If it's red or dusty, don't touch it!" above your siggy? I've been meaning to ask you for some time now and have always assumed that it's related to OH&S in the aircraft maintenance industry?

But after watching this film...

...there could be a completely non-aviation meaning to "don't touch the red dust"...

Thanks for the complement Graeme. Yes, Stainless steel is non-magnetic. The biggest advantage in using it in aircraft is its anti corrosive properties. It is weldable but it requires a "technique." I actually did some stainless steel welding when I was in A & P school many years ago, and lastly aircraft like the B-70 and Bristol 188 were probably non-magnetic. Keep in mind that several other alloys would of been used in their construction.

No my siggy - yes, it applies to aviation. This refers to being in the cockpit with out a full grasp of all the instruments and controls. If one sees something red, its assumed it for an emergency - if someone sees something dusty its assumed it hasn't been used for a while, hence the "red or dusty" warning.

Graeme · 05-04-2008, 07:55 AM

Quote:

Originally Posted by FLYBOYJ

If one sees something red, its assumed it for an emergency - if someone sees something dusty its assumed it hasn't been used for a while, hence the "red or dusty" warning.

Gotcha! Makes perfect sense now. Thanks.

evangilder · 05-04-2008, 10:44 AM

Speaking of that, they color code the items in the B-25s that fly today like that. When climbing in, they tell you "Grab the yellow, not the red handles" . Same idea. They are very near each other if you are going in the door near the front of the airplane too.

Kruska · 05-04-2008, 01:38 PM

Hello FLYBOY,

You seem to be very versed on flight topics, therefore I would like to forward the following question to you, even if it might sound dumb

to you and this thread could also be the wrong one:

How did the Allied Bomber crews prevent shooting down or at their own bombers? If I imagine 20-40 machineguns firing at a Luftwaffe a/c that dived through their formation, was there a regulation like; no fire at less than 200 or 400m range?

Off course I don’t mind any other forum member to help me on this question.

Regards
Kruska

FLYBOYJ · 05-04-2008, 02:13 PM

Quote:

Originally Posted by Kruska

Hello FLYBOY,

You seem to be very versed on flight topics, therefore I would like to forward the following question to you, even if it might sound dumb

to you and this thread could also be the wrong one:

How did the Allied Bomber crews prevent shooting down or at their own bombers? If I imagine 20-40 machineguns firing at a Luftwaffe a/c that dived through their formation, was there a regulation like; no fire at less than 200 or 400m range?

Off course I don’t mind any other forum member to help me on this question.

Regards
Kruska

Thanks Kruska!

And thank you for the compliment...

I've asked to question to a few B-17 and B-24 gunners I've met over the years. For the most part they told me it was actually pretty easy to avoid hitting another aircraft while in formation as gunners were taught to fire in very short burst. A gunner could expend all the ammo from his position in a matter of seconds so everything was done short and sparingly. Additionally radio communication was critical as well so the "box" knew when they were being attacked and from what direction.

Kruska · 05-04-2008, 02:29 PM

Hello Flyboy,

Thank you very much for your „rapid“ reply.

Yes short, disciplined and concentrated bursts make sense, also the awareness in regards to direction. Must have been quite a professional training behind the gunners.

Regards
Kruska

kool kitty89 · 05-04-2008, 05:23 PM

And stainless steel can be ferromagnetic depending on the type.

Both Iron and Nickel are ferromagnetic in pure form, Chromium is not, but certain alloys of iron (in this case with nickel) can form the non-ferro-magnetic austenitic iron matrix. Austenite - Wikipedia, the free encyclopedia
The most produced stainless steels are austenitic, but many common stainless alloys are magnetic, and even the austenitic alloys may be very weakly ferromagnetic due to the nickel content. Most high quality stainless cutlery will be nonmagnetic, but often cheaper types will be magnetic and often more prone to corrosion. Stainless steel used on appliances is also often magnetic as are stainless steel plate/sheet often found in hardware stores. Must stainless steel used for knives and cutting tools will also be ferro-magnetic.

See: Stainless steel - Wikipedia, the free encyclopedia

FLYBOYJ · 05-04-2008, 05:26 PM

Quote:

Originally Posted by kool kitty89

And stainless steel can be ferromagnetic depending on the type.

Both Iron and Nickel are ferromagnetic in pure form, Chromium is not, but certain alloys of iron (in this case with nickel) can form the non-ferro-magnetic austenitic iron matrix. Austenite - Wikipedia, the free encyclopedia
The most produced stainless steels are austenitic, but many common stainless alloys are magnetic, and even the austenitic alloys may be very weakly ferromagnetic due to the nickel content. Most high quality stainless cutlery will be nonmagnetic, but often cheaper types will be magnetic and often more prone to corrosion. Stainless steel used on appliances is also often magnetic as are stainless steel plate/sheet often found in hardware stores. Must stainless steel used for knives and cutting tools will also be ferro-magnetic.

See: Stainless steel - Wikipedia, the free encyclopedia

Stainless steels I seen used on aircraft ARE NOT magnetic.