I was viewing another forum about WW2 aircraft,and someone made a post that during the last weeks of the war the Japanese were so short of materals that they began making engine blocks for a purpose-built Kamikazi aircraft out of concrete. Has anyone else heard of this?
Wow. Never heard of such a beast. How cool would that be? That news would put GM out of business.lol. I'd build my own Harley big block fat boy.
That sounds highly unlikely, I cannot imagine of any circumstance in which a "concrete" could replace a metal in an engine block. Concrete has little shock resistance, hence the need for steel re-enforcing, and like it or not an internal combustion engine is nothing but impact after impact.
Also found nothing, but i guess cylinder liners and all the necessary connections in metal set in a concrete matrix could be made to work - it wouldn't be a true concrete engine block, merely replacing as much metal as possible with a 'filler'. Maybe would work for a single trip.
It seems hard to believe, but then when I read about concrete ships for convoy duty I said wtf? But we have one crumbling in Galveston bay.
I had heard of experimentation, in the 70s or 80s with ceramic engine blocks. That's kinda sorta not really like concrete I suppose.
I could imagine a relative of concrete that has long been available and was used for the base of really heavy engines called grout. Grout may have all of the properties that would enable an engine block only if metal sleeves were used for the cylinders and a proper pathway was designed in for effective cooling to avoid any high temps that would destroy the integrity of the grout. It would be suitable for lasting for a short amount of time due to its heat limitations. Grout is epoxy based material which has been used at times in repair of portions of some blocks. If i found it on a block I wouldn't buy it if I could avoid it.
Concrete has poor thermal performance relative to the needs of an internal combustion engine and is prone to explosive spalling when heated. Even cure concrete has a considerable moisture content in both free water in the pores and chemically combined water. When heated above 100°C, water turns to steam and the internal pressure within the pores spikes causing the explosive spalling. Studies were conducted in the 1950's on high temperature concrete and developments resulted in formulations that would withstand high temperatures, but I don't think that would include the rapid temperature changes that would occur in an engine. Concrete also needs considerable mass to withstand shock loading - not to mention considerable steel reinforcement. Building an engine with enough mass to withstand the loading would probably result in an engine too heavy to lift itself, much less an attached aircraft. Without seeing valid documentation to the contrary, I would be highly skeptical of such claims.
The Japanese had only two aero engines that could be said to have a block as us car-heads think of the term: the Ha-40 (licence built DB-60) and the virtually identical Atsuta 30, both inverted V-12. The rest were radials which don't have "blocks," per se. What functions as a block in a radial design is so small and of such a convoluted shape that concrete wouldn't be much of an advantage I would try to make a DB-601 out of wood before I'd try concrete. The Japanese did add concrete to many fighters used in the kamikaze role. A lightweight like a Zero or an Oscar couldn't carry a 500lbs bomb because the load shifted the center of gravity enough to make the plane unmanageable. They added lead, and later concrete ballast to restore the balance.
I doubt that very much. Concrete would not stand up to the vibration of an engine well. How would various components be attached to it and how would it be assembled? You couldn't get high strength / high torque bolts in place on it. How could you machine the surfaces sufficently flat and true to allow for sealing of the heads, piston rings, etc? That would be incredibly difficult to do even today using highly accurate grinding techniques like blanchard or centerless with media like ALO or SiC that didn't even really exist in industry back then.
Thank you all for your posts.I had my doubts about it,but the OP stated that he got the information from Hideo "Pops"Yoshimura,who was an aircraft mechanic and after the war started the Yoshimura motorcycle racing team. I guess that "Pops"was pulling his leg
Well, when you remember how many "short cuts" they (Japanese) were taking at the wars end, that really isn't that much of a "stretch". The Japanese were no longer using brass for their cartridge casings (iron), and much of their gasoline was made from distilling pine-nuts. Desperate time spawn desperate measures, so the "idea" of concrete engine blocks might not have seemed so outrageous for a "one way mission".
Steel shell casings are not uncommon. The Germans used these extensively. The US started using Aluminum and steel ones. This is not uncommon. Making gasoline or "wood gas" was common in Germany too. In fact, even the British had some civilian vehicles that ran on wood gas generators. But a concrete engine block is something else altogether. I don't think it is even possible. Concrete Engine Block with Liners
Remember, concrete and cement are not the same thing. Concrete is cement with some form of filler. You can use fiberglass and it makes a very lightweight and suitable material. I know, because I once won a national concrete canoe contest. A concrete canoe made with fiberglass will actually hold a person when the whole canoe is full of water. Its actually pretty cool stuff, its much easier to cast than regular fiberglass, but it takes a long long time to cure, like months. An engine block could absolutely be made of it, with the proper metal inserts. What I want to know is how they intend to cool it. If it did happen, its likely they made a pretty complete engine with a very thin block, and reinforced it with cement/fiberglass. That way they can reduce the amount of metal used in the casting of the block.
Ha...CPL... Maybe a DB 601 made out of petrified wood? ....I want Jdgrmstr to build me a canoe, eh. Captain Canoe eh.
The Japanese version wasn't a "wood gas" which was common through out the ETO as the war went on for civilian use. What the Japanese were doing was gathering pine nuts, and turning them into liquid fuel. A completely separate system, they also used "wood gas" to power cars and such, but they were down to using "iron", not steel for their shell casing, and pine nuts to make liquid fuel to substitute for a petroleum based gasoline for their aircraft! I agree however with the "concrete block" idea, even a radial engine design would put too much stress on even re-enforced concrete of the era to last long enough to get an aircraft airborne.
