Reiwa Chemist Yōko Takatsukasa Reincarnation: Saving Japan with Plastic Material

Kites Are Also in the Accipitridae Family

The production of a close air support aircraft more than 20 years ahead of the original timeline caused a flurry of activity within the Teijin Company. The design reused elements from the previous Tonbi model as much as possible while incorporating two newly developed engines in tandem. They also added 2 meters of tapered wings at the wingtips, which could function as ailerons, in an effort to increase payload capacity.

"But the target maximum output is 100 horsepower..."

"The Grade engines we used before were only 16 horsepower. Can we really increase it by more than six times?"

"We can't do it on our own, but we should seek help from the Osaka Artillery Arsenal."

In this world, the Osaka Artillery Arsenal is responsible for producing the Type 44 transport vehicle itself. While they import engines, they are also conducting research on domestic production and have already produced several prototypes. Seeking advice and ordering prototypes from them seems to be the best option available domestically.

'This world hasn't yet realized the great potential of two-stroke engines. In this era without emission regulations...'

Yōko noticed that the Grade engine was a two-stroke engine. Two-stroke engines could deliver high power despite their small displacement, and their simple design made them easy to manufacture. In the later years of the Shōwa era, most motorcycle and light vehicle engines were two-stroke engines. However, the Day two-stroke engines of this time were not designed for high output; they were designed to avoid existing patents, resulting in poor thermal efficiency and low output. To improve this, Yōko incorporated the following technologies:

1. Forced induction using a root blower.

2. Loop scavenging (Schnuerle porting).

3. Using a horizontal opposed four-cylinder configuration, ensuring that two cylinders fired simultaneously.

4. Connecting cylinders with the same ignition timing through an exhaust manifold to prevent scavenging interference.

5. Introducing squish areas on the cylinder head side.

The key to two-stroke engine operation lies in its working principle. Modern four-stroke engines go through four processes—intake, compression, expansion, and exhaust—twice within two revolutions. Since one cycle is completed after four piston strokes, they are known as four-stroke engines.

On the other hand, two-stroke engines complete one cycle within one revolution, which means they use a method called scavenging to expel exhaust gases through the intake. This often led to a phenomenon called "blow-through," where the fresh mixture sucked in was immediately expelled through the exhaust.

In the later years of the Shōwa era, two-stroke engines often used a bulge in the exhaust pipe to redirect exhaust gases back into the cylinder to push out the blow-through mixture. However, it was also possible to achieve the same effect by cleverly connecting the exhaust gases through an exhaust manifold and adjusting the ignition sequence. While this phenomenon is undesirable and leads to decreased engine output in four-stroke engines, it is actively induced in two-stroke engines to pack as much mixture as possible into the cylinder. By equipping a root blower and a supercharger, and implementing loop scavenging to improve scavenging efficiency by momentarily directing fresh mixture against the cylinder wall, they achieved remarkable horsepower per unit displacement for their time.

There were some setbacks, such as Yōko leaving the development team for her exams during the design process, but the prototype aircraft produced by Teijin demonstrated excellent performance that was on par with or even superior to the aircraft of European powers. In 1914, it was officially adopted without waiting for the completion of the design prototype.

Teijin TP22A Type 3 Attacker "Kinshi" Model 1

- Airframe : High-wing monoplane, push-pull engine configuration

- Fuselage : Tubular steel frame (cockpit section covered with nylon and polycarbonate plates)

- Wing : Rectangular wing, GFRP/nylon frame upholstered

-- 2 m from the wingtip, tapered wing with winglets, steel tube/nylon frame upholstered

-- Airfoil : (resembling) DAE21

-- Flaps : Split flaps

-- Notes : Equipped with dive brakes

- Crew : 1

- Length : 8,7 m

- Wingspan : 14,2 m

- Dry weight : 220 kg

-- Overall weight : 800 kg

- Engine : Teijin A040A forced-swept 2-stroke air-cooled horizontally opposed 4-cylinder, 120 hp × 2

- Maximum speed : 215 km/h

- Cruising range : 500 km

- Maximum ceiling : 6.000 m (3.000 m with bombs)

- Armament :

-- 4 × Type 38 machine gun (cloth ammunition belt)

-- 8 × 45 kg bombs (Type 45 armor-piercing high-explosive bomb)

The notable external features of this aircraft include the placement of the vertical tail fin in an inverted position compared to conventional aircraft, with a tailwheel attached to its tip to prevent the propeller at the rear of the aircraft from hitting the ground during takeoff. Additionally, to maintain balance, the cockpit and main wings are shifted considerably toward the rear of the aircraft compared to the Tonbi, giving it an appearance that some observers jokingly referred to as a "clothesline."

However, as mentioned earlier, its performance was exceptionally high. When armed with bombs, it could accurately deliver up to eight 15 cm shells and could hold its own against enemy fighters with its fixed forward-facing machine guns when not carrying bombs. However, when tasked with bombing missions, the lightweight design in relation to its bomb-carrying capacity posed a challenge, requiring careful attention to the drastic changes in handling characteristics with each bomb dropped. Additionally, during engagements with enemy fighter planes, its large wingspan resulted in a noticeably lower roll rate, which was a weakness that had to be considered. Furthermore, the Type 38 machine guns mounted on the front had a slow rate of fire and lacked the firepower needed for air-to-air combat. They also lacked tracer rounds and incendiary armor-piercing ammunition, leading to dissatisfaction with the perception that "even if you shoot, the enemy won't go down."

Despite these drawbacks, the aircraft had distinct strengths. Since Japan did not possess any other substantial aircraft at the time, it eventually saw the production of 300 units and the development of a small seaplane variant for the Navy, laying the foundation for the future Teijin Aircraft Company. It became a significant and memorable aircraft in that regard.

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In the original timeline, it is noted that in February 1909, the Osaka Artillery Arsenal conducted engine prototype testing. In May 1911, they also began manufacturing domestically produced trucks. However, when they attempted a test run, there were no significant issues on the outbound journey, but as expected, the truck broke down on the return trip, forcing them to tow it back with horses.

I had always intended to change Japan's engine landscape with two-stroke engines, but it worked out quite smoothly when Grade's monoplane engine turned out to be a two-stroke engine. I wonder if there's a documentary about the introduction of two-stroke engines in Japan. I haven't seen one myself.

- Toshitsugu Utei