# Can you build an aircraft using steel? **URL:** \ **Category:** Factual Questions\ **Created:** [April 21, 2018, 12:19pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859 "2018-04-21T12:19:43Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![Luke\_who\_s\_here](https://avatars.discourse-cdn.com/v4/letter/l/22d042/32.png) [@Luke\_who\_s\_here](https://boards.straightdope.com/u/Luke_who_s_here)\ **Post date:** [April 27, 2018, 7:46am UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/21 "2018-04-27T07:46:32Z")
I recall the V-1 flying bomb also had sheet steel in its air frame. It was hard shooting it down with machine guns; and dangerous with cannon, since the fighter had to come up close. ---
**Author:** ![AK84](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@AK84](https://boards.straightdope.com/u/AK84)\ **Post date:** [April 27, 2018, 9:09am UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/22 "2018-04-27T09:09:25Z")
> [@Llama\_Llogophile](#): > > IIRC, western intelligence was surprised to find the MiG-25 was constructed with a lot of steel when they got hold of the one Victor Belenko used to defect. That also accounted for the ridiculously huge engines, which were needed for all of that weight. > > This is not to say the plane was badly constructed or designed. The U.S. wouldn’t have built a plane that way because we had access to better materials and facilities. There was actually some clever engineering on the MiG-25, given the circumstances of its provenance and the conditions under which it would likely operate. But in the end, the weight required some brute force in the form of huge engines. No, the US famously did **not** have access to better materials, Titanium reserves at that time were mostly in Russia and the metal was heavily used in the USSR (for example in their submarines and missiles) while the CIA had to “source” Titanium for use in A-12 and SR-71. Hell Boeing had to “trade” with the Sovs for information on titanium casting, for the 747, and to this day the Russians [are the biggest makers of engineered Titanium products.](https://www.deccanherald.com/content/344000/boeing-sources-titanium-parts-russia.html) Why they used a steel-nickle alloy for the Foxbat, has not yet been satisfactorily explained. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [April 28, 2018, 8:30am UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/23 "2018-04-28T08:30:20Z")
> [@AK84](#): > > No, the US famously did **not** have access to better materials, Titanium reserves at that time were mostly in Russia and the metal was heavily used in the USSR (for example in their submarines and missiles) while the CIA had to “source” Titanium for use in A-12 and SR-71. I find that hard to believe. Just before WW II , Kroll fled europe to the USA and developed an efficient titanium process , which bears his name, for the USA. By 1947, they had made various modifications to Kroll’s process and produced nearly 2 tons of titanium metal. In 1948, DuPont opened the first large scale manufacturing operation. Read more: [How titanium is made - material, manufacture, making, history, used, processing, parts, components, composition](http://www.madehow.com/Volume-7/Titanium.html#ixzz5DxCo1YPu) USA has numerous sources of titanium, and Canada and Australia have huge amounts, some sites suitable as viable modern commercial mines ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [April 28, 2018, 12:54pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/24 "2018-04-28T12:54:01Z")
I suspect the issue with A-12 and SR-71 titanium was probably not so much the lack of titanium in the US, but the lack of capability to produce titanium of the particular grade needed. Titanium is evil stuff to manage, and much of the strength and other properties can be hard to find or easily lost if you get it wrong. The Russians were significantly more advanced in their understanding of how to manage the metal and its alloys in demanding uses. And the Blackbirds were certainly that. Pretty much every source on the history of those aircraft notes that the CIA did procure some titanium clandestinely from the USSR. I could imagine that the US didn’t have the capability to produce say, sheet material of such thin section and with the needed physical properties. The exchange of information with Boeing is fairly well known. There was a trade in a restaurant in Paris during the Paris Air Show, in which the Russians revealed techniques for casting and the like which Boeing needed (for instance they had gone so far over the weight budget of the 747 that the undercarriage had to be made of titanium, which they didn’t know how to do) in exchange for the basics of how to build a flexible swept wing jet aircraft. One description of the meeting is here: [The Titanium Gambit | Air & Space Magazine| Smithsonian Magazine](https://www.airspacemag.com/history-of-flight/the-titanium-gambit-3804526/) There were stories after the breakup of the Soviet Union of military quality titanium stock being used for the manufacture of things like shovels, as the factory had no money coming from the military and a desperate need for income. I would kill for one of those shovels. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [April 28, 2018, 1:03pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/25 "2018-04-28T13:03:11Z")
> [@AK84](#): > > Why they used a steel-nickle alloy for the Foxbat, has not yet been satisfactorily explained. A “steel-nickel alloy” may well be something like the Inconel family or Hastalloys. If you are getting really hot you will want to use these. They aren’t steels, indeed only contain small amounts of iron, but things get lost in translation or communication. They can look a lot like stainless steel. ---
**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\ **Post date:** [April 28, 2018, 7:52pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/26 "2018-04-28T19:52:36Z")
> [@Francis\_Vaughan](#): > > I suspect the issue with A-12 and SR-71 titanium was probably not so much the lack of titanium in the US, but the lack of capability to produce titanium of the particular grade needed. Titanium is evil stuff to manage, and much of the strength and other properties can be hard to find or easily lost if you get it wrong. The Russians were significantly more advanced in their understanding of how to manage the metal and its alloys in demanding uses. And the Blackbirds were certainly that. Pretty much every source on the history of those aircraft notes that the CIA did procure some titanium clandestinely from the USSR. I could imagine that the US didn’t have the capability to produce say, sheet material of such thin section and with the needed physical properties. The USSR had (and Russia has) large reserves of titanium in raw form which is what is said to have been clandestinely procured as part of the SR-71 program, rutile ore or semi-processed titanium sponge depending on version of the story. However, per post-Soviet Russian sources, the reason the MiG-25 had so little titanium in its structure, or that stainless steel was viewed as preferable, was limitations in Soviet ability at the time to produce thin sections as for a/c. Which Lockheed obviously was able to do. This wasn’t true for all uses of titanium. The Soviets perfected practical welding of thick titanium plates for submarine hulls for example. The US never seriously considered this on cost grounds. However it’s said it was still difficult to replicate ‘obtained’ examples of Soviet welded titanium structures. Nowadays Russian supply of titanium to the world aircraft manufacturing market includes finished pieces, but it didn’t in case of the SR-71 (that would have been _really_ a story, even more than the already interesting story of titanium raw material from the USSR being used). ---
**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\ **Post date:** [April 28, 2018, 10:02pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/27 "2018-04-28T22:02:41Z")
> [@Francis\_Vaughan](#): > > A “steel-nickel alloy” may well be something like the Inconel family or Hastalloys. If you are getting really hot you will want to use these. They aren’t steels, indeed only contain small amounts of iron, but things get lost in translation or communication. They can look a lot like stainless steel. Just PS on that point, the steel portions of the MiG-25 are given here as types SN-3, VL-1, VNS-2, VNS-5, EI-703, and EI-878. [http://biblioteka.mycity-military.com/biblioteka/Vule/AVIO%20PUBLIKACIJE/MiG-25%20%26%20MiG-31%20(Aircraft%20Military%20Fall%201998).pdf](http://biblioteka.mycity-military.com/biblioteka/Vule/AVIO%20PUBLIKACIJE/MiG-25%20%26%20MiG-31%20(Aircraft%20Military%20Fall%201998).pdf) An at least largely overlapping list is seen elsewhere. Some sources characterize the VNS series as high strength carbon steel but the composition of VNS-2 given here is a stainless steel. > **[Steel 08Х15Н5Д2Т (ЭП410; VNS-2; ЭП225) / Auremo](https://auremo.biz/materials/stal-08h15n5d2t-ep410-vns-2-ep225.html)** > > Steel 08Х15Н5Д2Т (ЭП410; VNS-2; ЭП225) EI-703 happens to also appear in this series of pages and given as 36% Ni and 21% Cr, so fairly close to SAE 330 which is still considered a steel despite being less then 50% iron. > **[Alloy KHN38VT (ЭИ703) / Auremo](https://auremo.biz/materials/splav-hn38vt-ei703.html)** > > Alloy KHN38VT (ЭИ703) Without chasing down the composition of each, it seems the common characterization of the materials as stainless steel is at least largely accurate. ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [April 30, 2018, 3:51pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/28 "2018-04-30T15:51:06Z")
Not a modern aircraft by any stretch but the [IL-2 Sturmovik](https://en.wikipedia.org/wiki/Ilyushin_Il-2) mentioned in another thread used steel, battleship steel at that and flew well enough to scare the bejeezus out of Tiger crews once they crews figured out how to use the plane. ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [April 30, 2018, 6:05pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/29 "2018-04-30T18:05:47Z")
> [@Francis\_Vaughan](#): > > A “steel-nickel alloy” may well be something like the Inconel family or Hastalloys. If you are getting really hot you will want to use these. They aren’t steels, indeed only contain small amounts of iron, but things get lost in translation or communication. They can look a lot like stainless steel. But those superalloys work-harden like crazy and would be similar to the titanium alloys of the era in workability. Besides, if Wikipedia is to be believed, the temperatures involved aren’t that hot compared to the hot portion of a gas turbine (which is where Inconel and similar alloys are typically used). I’ve seen 600-800 degrees F for the SR-71 Blackbird at Mach 3-3.2, while the MIG-25 was redlined at about Mach 2.8. I can’t prove it, but the use of fairly conventional stainless steels may well be due to Russian thinking about combat aircraft design in general: Soviet aircraft tended to be a little crude but robust, while American aircraft were more sophisticated but delicate. The idea, as I understand it, is that in the event of a major conflict with the West, the Soviets expected to operate from degraded, isolated airfields with little infrastructure. The SR-71 had to be washed with distilled water because chlorine from tap water would react with the titanium skin at operating temperatures. Similarly, it required dedicated hand tools because the cadmium in plated conventional tools embrittlement titanium. Oh: and for a while, it used special cesium-spiked fuel. A stainless MIG-25 could be washed with whatever water was handy and its airframe could be worked on with standard tools. This kind of robustness is similar to that provided by its vacuum-tube-based avionics, which were less vulnerable than Western integrates circuits to the EMPs one would expect in a nuclear war. But it’s problematic to connect stainless steel to titanium when both get hot; most stainlesses have a coefficient of thermal expansion nearly double that of most titaniums. When they get hot, they expand at different rates and enormous stresses can result. So a stainless skin on a plane that gets hot means that much of the airframe must be stainless too. You end up with a slightly crude, very heavy (but very fast) plane that’s just the thing for stationing at remote, poor-infrastructure airbases near the borders. They’d be great for intercepting supersonic American bombers like the B-58 Hustler (and even the SR-71, I’d imagine) while enduring ugly field conditions. That the MIG-25 wasn’t made from titanium might seem surprising on the face of it, but the Soviet penchant for weapons that work well in suboptimal conditions explains a lot of it, I think. Besides, the vacuum-tube avionics suggest that robustness in the face of a drawn-out war was an explicit design goal for the MIG-25. It’s not just aircraft, either. Anyone who compares the design philosophies behind the AR-15 and the AK-47 assault rifles reaches a similar conclusion about which side valued what traits in its weapons. ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [April 30, 2018, 6:19pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/30 "2018-04-30T18:19:28Z")
> [@swampspruce](#): > > Not a modern aircraft by any stretch but the [IL-2 Sturmovik](https://en.wikipedia.org/wiki/Ilyushin_Il-2) mentioned in another thread used steel, battleship steel at that and flew well enough to scare the bejeezus out of Tiger crews once they crews figured out how to use the plane. I understand the AB-1 steel used on the IL-2 to be essentially rolled homogenous armor (RHA). If that’s true, I don’t see that “battleship steel” is somehow distinct from “tank steel” or “steel armor plate.” Lots of Allied planes used armor plate behind the cockpit and in other critical areas. The IL-2 used a lot more of it than other planes, though, and also used it as a load-bearing structure, which was novel at the time. Is there some reason to call it “battleship steel” that I’m missing? ---
**Author:** ![DavidwithanR](https://avatars.discourse-cdn.com/v4/letter/d/3bc359/32.png) [@DavidwithanR](https://boards.straightdope.com/u/DavidwithanR)\ **Post date:** [April 30, 2018, 6:41pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/31 "2018-04-30T18:41:24Z")
> [@Chronos](#): > > That’s sort of Soviet engineering in a nutshell, there. Use the best materials and technology you’ve got, and when that’s lacking, make up for it with lots and lots of brute force. Isn’t that actually _everyone’s_ engineering in a nutshell? I think people 100 years from now will look back on late-20th-early-21st-century American engineering and be surprised at the amount of brute force our methods required. It’s all perspective, all relative. Good engineering equals creating maximum success given what you’ve got. ETA: And (noticing intervening posts) given the assumptions you’re working under. ---
**Author:** ![DavidwithanR](https://avatars.discourse-cdn.com/v4/letter/d/3bc359/32.png) [@DavidwithanR](https://boards.straightdope.com/u/DavidwithanR)\ **Post date:** [April 30, 2018, 6:48pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/32 "2018-04-30T18:48:04Z")
> [@EdelweissPirate](#): > > Is there some reason to call it “battleship steel” that I’m missing? Would make sense if it was physically brought over from a shipyard. ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [April 30, 2018, 7:13pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/33 "2018-04-30T19:13:34Z")
> [@EdelweissPirate](#): > > I understand the AB-1 steel used on the IL-2 to be essentially rolled homogenous armor (RHA). If that’s true, I don’t see that “battleship steel” is somehow distinct from “tank steel” or “steel armor plate.” Lots of Allied planes used armor plate behind the cockpit and in other critical areas. The IL-2 used a lot more of it than other planes, though, and also used it as a load-bearing structure, which was novel at the time. > > Is there some reason to call it “battleship steel” that I’m missing? It sounds marginally more impressive? I know armor is basically armor but the notion of a flying dreadnaught appeals to me, although I wouldn’t want to be underneath it when it crashes down…😃 ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [May 1, 2018, 5:02pm UTC](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859/34 "2018-05-01T17:02:07Z")
> [@Francis\_Vaughan](#): > > There were stories after the breakup of the Soviet Union of military quality titanium stock being used for the manufacture of things like shovels, as the factory had no money coming from the military and a desperate need for income. I would kill for one of those shovels. Would you settle for a [spork](https://www.rei.com/product/660002/snow-peak-titanium-spork)? I’ve considered those to be the biggest waste of good material since [spoilers](https://www.theglobeandmail.com/globe-drive/culture/commuting/do-spoilers-actually-improve-a-cars-performance/article21180268/) on econo-boxes. [Previous page](https://boards.straightdope.com/t/can-you-build-an-aircraft-using-steel/812859.md?page=1)