Rikugun Ki-328. Japanese rocket powered vertical take-off interceptor

[RAFF-35]

So with only 9 parts to the entire kit, I've had longer sneezes than the total assembly time! The next thing to work out is what booster system to use? I only have 3 Schmidding SG.34 boosters. Or should I use a single, larger booster slung underneath the Ki.328?

Raff ..bad ideas GB mate...use all of em!!!   

Now you've said that, I've just thought that I should've done a Bolhm & Voss designed interceptor so there was asymmetric thrust thrown into the mix too 

[PR19_Kit]

Use a V2 as the booster stage...................... 

[Wardukw]

So with only 9 parts to the entire kit, I've had longer sneezes than the total assembly time! The next thing to work out is what booster system to use? I only have 3 Schmidding SG.34 boosters. Or should I use a single, larger booster slung underneath the Ki.328?

Raff ..bad ideas GB mate...use all of em!!!   

Now you've said that, I've just thought that I should've done a Bolhm & Voss designed interceptor so there was asymmetric thrust thrown into the mix too 

Ya still can but the Japanese version..think of it as the unintentional kamikaze   

[Wardukw]

Use a V2 as the booster stage...................... 

Hahahaha 😆 😂 😆...dude I love that idea 😂

[frank2056]

Don't laugh - the BIS suggested building a larger, manned version of the V-2 called Megaroc.

whatif video:

[Wardukw]

That doesn't surprise me at all really...but the thinking behind might prove the downfall...scaling something up and thinking it's going to work perfectly often has a habit of proving it don't work 🤔 😅

[kerick]

That doesn't surprise me at all really...but the thinking behind might prove the downfall...scaling something up and thinking it's going to work perfectly often has a habit of proving it don't work 🤔 😅

In a larger and more spectacular way! Huge ball of fire, enormous cloud of smoke!

[RAFF-35]

I found some more time to work on this build, so I've added some little details here and there including a turbine generator and a booster rocket. I have modelled the booster roughly on a Schmidding 109-553, but to be built locally by Mizuno.

The second photo is taken from the interweb to illustrate what the Schmidding should look like.

[Wardukw]

Well that looks incredibly small mate 😳 👍
Nobody in their right mind would get into that with all those rockets and boosters and hope of coming back in at least one piece....many many pieces..very plausible 😆

[kerick]

I don't know what any of these designers were thinking. They must have thought pilots were super human.

[PR19_Kit]

I don't know what any of these designers were thinking. They must have thought pilots were super human.

They figured they were expendable..................

[kerick]

I don't know what any of these designers were thinking. They must have thought pilots were super human.

They figured they were expendable..................

Surviving the launch to accomplish the mission would be tough enough.

[RAFF-35]

Well that looks incredibly small mate 😳 👍
Nobody in their right mind would get into that with all those rockets and boosters and hope of coming back in at least one piece....many many pieces..very plausible 😆

It's probably the smallest aircraft kit I've ever built in 1:72.

Luckily Japanese culture embraced one-way flights 

[Wardukw]

Well that looks incredibly small mate 😳 👍
Nobody in their right mind would get into that with all those rockets and boosters and hope of coming back in at least one piece....many many pieces..very plausible 😆

Yes yes yes .that they did indeed ..would make a sucky airline tho ..no return flights 

I think the smallest 72nd plane I built..maybe a Tigermoth or a Bulldog ...one of them 

It's probably the smallest aircraft kit I've ever built in 1:72.

Luckily Japanese culture embraced one-way flights 

[RAFF-35]

The Rikugun Ki-328 was one of the most audacious yet deeply flawed aircraft projects undertaken by Japan during the final years of the Second World War. A product of necessity and desperation, the Ki-328 emerged from an attempt to reconstruct German interceptor designs using incomplete plans delivered by U-boat. The resulting aircraft bore a passing resemblance to the Messerschmitt Me-328 but functioned more like the Bachem Ba 349 Natter. Despite the theoretical advantages of rapid interception and reusability, the Ki-328 was plagued by significant operational dangers, technological limitations, and practical constraints.

The Ki-328 was powered by the Mitsubishi Toku Ro.3 rocket motor, a derivative of the German HWK 109-509 engine. This gave the interceptor an extraordinary climb rate but at the cost of extremely limited endurance. The aircraft was designed for vertical takeoff under autopilot control, followed by a rapid engagement phase where the pilot would fire a salvo of 32 unguided rockets into an incoming formation of B-29 bombers. Once its fuel was expended, the Ki-328 was supposed to glide away from enemy defenses before separating into sections to be recovered via parachute for reuse.

However, from the very beginning, the aircraft proved exceptionally hazardous to operate. Test flights revealed a series of critical flaws:

Unreliable Autopilot: The rudimentary autopilot was prone to failure, often causing the aircraft to veer off course or become uncontrollable. Many test units crashed shortly after launch, rendering the concept of vertical takeoff highly problematic.

Pilot G-Forces and Stress: Pilots experienced extreme acceleration forces upon launch, making it difficult to remain conscious and control the aircraft. This, combined with the rapid transition from autopilot to manual control, led to a high failure rate during combat.

Rocket Salvo Issues: The 32 unguided rockets were notoriously inaccurate, requiring the pilot to approach dangerously close to enemy formations for effective use. This exposed the Ki-328 to defensive fire from bombers.

Lack of Safe Recovery: The parachute recovery system for the aircraft's sections rarely functioned as intended. Many aircraft were lost when the fuselage failed to separate properly or when parachutes failed to deploy, making reusability almost impossible in practice.

EXTREMELY HAZARDOUS FUEL: The rocket motor itself posed an extreme hazard to both pilots and ground crews. The HWK 109-509 engine ran on a hypergolic propellant combination of T-Stoff (highly concentrated hydrogen peroxide) and C-Stoff (a mix of hydrazine hydrate and methanol). T-Stoff was highly corrosive and could cause severe chemical burns upon contact with skin, while C-Stoff was highly toxic and volatile. The slightest contamination or improper handling could result in catastrophic explosions. Additionally, leaks in the fuel system often led to deadly accidents on the ground and in the air.

Despite these flaws, Japan's dire war situation necessitated that the Ki-328 be rushed into operational use in mid-1945. A handful of aircraft were assembled and launched in a last-ditch effort to intercept B-29 formations bombing Japanese cities. Results were mixed at best. While some Ki-328s successfully reached their targets and fired their rocket salvos, their effectiveness remained questionable due to poor accuracy and limited survivability.

Several Ki-328 pilots perished either due to mechanical failures or blowing up due to the volatile propulsion method. The lack of an ejection system left pilots with no choice but to attempt controlled crash landings or bail out at dangerous speeds. Recovery crews often struggled to locate and salvage the remains of the aircraft, further diminishing the interceptor's theoretical advantage of reuse.

Ultimately, the Ki-328 was more a testament to Japan's wartime desperation than a viable weapon system. Its dangers far outweighed its advantages, and it posed as much risk to its own pilots as to enemy bombers. By the time Japan surrendered in August 1945, only a handful of Ki-328s had been used in combat, and the design was quickly abandoned.