Nakajima Kikka

https://en.wikipedia.org/wiki/Nakajima_Kikka

The Nakajima Kikka (?? ?? "Orange Blossom") was Japan's first jet aircraft. It
was developed late in World War II and the first prototype had only flown once
before the end of the conflict. It was also called Kokoku Nigo Heiki (??????
"Imperial Weapon No.2").

After the Japanese military attaché in Germany witnessed trials of the
Messerschmitt Me 262 in 1944, the Imperial Japanese Navy issued a request to
Nakajima to develop a similar aircraft to be used as a fast attack bomber. Among
the specifications for the design were the requirements that it should be able
to be built largely by unskilled labor, and that the wings should be foldable.
This latter feature was to enable the aircraft to be hidden in caves and tunnels
around Japan as the navy began to prepare for the defense of the home islands.
Nakajima designers Kazuo Ohno and Kenichi Matsumura laid out an aircraft that
bore a strong but superficial resemblance to the Me 262.

The Kikka was designed in preliminary form to use the Tsu-11, a very crude
thermojet style of jet engine that was little more than a ducted fan with an
afterburner. Subsequent designs were planned around the Ne-10 (TR-10)
centrifugal-flow turbojet, and the Ne-12, which added a four-stage axial
compressor to the front of the Ne-10. Tests of this powerplant soon revealed
that it would not produce anywhere near the power required to propel the
aircraft, and the project was temporarily stalled. It was then decided to
produce a new axial flow turbojet based on the German BMW 003.

Development of the engine was troublesome, based on little more than photographs
and a cut-away drawing; but a suitable unit, the Ishikawajima Ne-20, was finally
built. By mid-1945, the Kikka project was making progress once again and at this
stage, reflecting the deteriorating war situation, it is possible that the Navy
considered employing the Kikka as a kamikaze weapon although the prospect was
questionable due to the high cost and complexity associated with contemporary
turbojet engines. As well, other more economical projects meant specifically for
the role such as the simple Nakajima Toka (designed to absorb Japanese stock of
obsolete engines), the pulsejet-powered Kawanishi Baika, and the infamous
Yokosuka Ohka, were either underway or already in mass production.

Compared to the Me 262, the Kikka airframe was noticeably smaller and more
conventional in design, with straight (rather than swept) wings and tail
surfaces. The triangular fuselage cross section characteristic of the German
design was less pronounced, due to smaller fuel tanks. The main landing gear of
the Kikka were taken from the A6M Zero and the nose wheel from the tail of a
Yokosuka P1Y bomber.

The Kikka is often identified as the Nakajima J9N1, or occasionally J9Y, which
according to a researcher at the National Air and Space Museum is incorrect. The
official name given to the aircraft was ?? "Kitsuka," pronounced Kikka in Kanji
used traditionally by the Japanese. Like other Japanese aircraft intended for
use in suicide missions, it received only a name.


Role
Ground Attack
Anti-ship, including Kamikaze

Manufacturer
Nakajima

Designer
IJA-AS

First flight
7 August 1945

Retired
15 August 1945

Status
Prototype

Primary user
Imperial Japanese Navy

Number built
10

The first prototype commenced ground tests at the Nakajima factory on 30 June
1945. The following month it was dismantled and delivered to Kisarazu Naval
Airfield where it was re-assembled and prepared for flight testing. The first
flight took place on 7 August 1945, with Lieutenant Commander Susumu Takaoka at
the controls. The aircraft performed well during a 20-minute test flight, with
the only concern being the length of the takeoff run. For the second test
flight, four days later, rocket assisted take off (RATO) units were fitted to
the aircraft. The pilot had been uneasy about the angle at which the rocket
tubes had been set, but with no time to correct them they decided to simply
reduce the thrust of the rockets from 800 kg to only 400 kg. Four seconds into
take off the RATO was actuated, immediately jolting the aircraft back onto its
tail leaving the pilot with no effective tail control. After the nine-second
burning time of the RATO ran out the nose came down and the nose wheel contacted
the runway, resulting in a sudden deceleration, however both engines were still
functioning normally. At this point the pilot opted to abort the take off, but
fighting to brake the aircraft and perform a ground loop only put him in danger
of running it into other installations. Eventually the aircraft ran over a
drainage ditch which caught the tricycle landing gear, the aircraft continued to
skid forward and stopped short of the water's edge. Before it could be repaired
Japan had surrendered and the war was over.

At this point, the second prototype was close to completion, and approximately
23 more airframes were under construction. One of these was a two-seat trainer.
Other follow-on versions proposed had included a reconnaissance aircraft, and a
fighter armed with two 30 mm Type 5 cannons with 50 rounds per gun. These were
expected to be powered by more advanced developments of the Ne-20, known as
Ne-20-Kai 5.59 kN (570 kgf) or Ne-130 8.826 kN (900 kgf) or Ne-230 8.679 kN (885
kgf) or Ne-330 13.043 kN (1330 kgf), which were planned to have approximately
15% to 140% better thrust than the Ne-20.

After the war, airframes 3, 4, and 5 (and possibly other partial airframes) were
brought to the U.S. for study. Today, only a single example survives in the
National Air and Space Museum: a Kikka that was taken to the Patuxent River
Naval Air Base, Maryland for analysis. This aircraft is very incomplete and is
believed to have been patched together from a variety of semi-completed
airframes.

Two Ne-20 jet engines had been taken to the US and sent for analysis to the
Chrysler Corporation in 1946. This was only revealed in 2005 by W. I. Chapman,
who was in charge of the project at the time. A working engine was assembled
with the parts of the two Ne-20s, and tested for 11 hours and 46 minutes. A
report was issued on 7 April 1947, titled "Japanese NE-20 turbo jet engine.
Construction and performance". The document is now on display at the Tokyo
National Science Museum.

Specifications

General characteristics
Crew: 1
Length: 8.125 m (26 ft 8 in)
Wingspan: 10.00 m (32 ft 10 in)
Height: 2.95 m (9 ft 9 in)
Wing area: 13.21 m² (142 ft²)
Empty weight: 2,300 kg (5,071 lb)
Loaded weight: 3,500 kg (7,716 lb)
Max. takeoff weight: 4,080 kg (8,995 lb)
Powerplant: 2 × Ishikawajima Ne-20 turbojets, 4.66 kN (475 kgf) each

Performance
Maximum speed: 696 km/h (432 mph)
Range: 943 km (586 mi)
Service ceiling: 12,000 m (39,370 ft)
Rate of climb: 385 m/min (1,262 ft/min)

Armament

Guns: 2 × 30 mm Type 5 cannon
Bombs: 1 × 500 kg (1,102 lb), or 1 × 800 kg (1,764 lb)



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