Was there ever anything published about its testing?
"What If" the thing had flown against 47N's and the P51H?
If any recorded flight test data survived the war, I'd imagine that we picked it up when we took possession of the two prototypes after the surrender. In the book "Japanese Secret Projects Experimental Aircraft-1939-1945" it mentions that the tests of the first prototype pulled to the right on take off due to the torque and at the speeds that the first test was flown (max speed 161mph), the strong right torque was present at all speeds tested. Landing was tricky due to the torque, inclination of the nose and relatively high landing speed (149mph) and if rudder was used during landing the nose would pop up just before touchdown.
2nd test was to test mainly for maneuverability. The pilot, Yoshitaka Miyaishi, found that during the climb to test altitude (1,610ft) the nose wanted to dip and as with the first test flight, the strong right torque was still evident. There was also engine cooling issues that were first discovered in the static engine test a few months earlier. At the time of the static tests, the engine cooling issues was thought to be because of the lack of airflow during the static tests. During the three test flights, as the flights went on the oil temperature rose.
The 3rd flight was equally as short as the other two flights. With Miyaishi again at the controls, he took off on August 8th for the final test flight. He noted that there was strong vibrations in the fuselage, caused by the torque and from the extension shaft that mated the propeller to the engine. He also noted that the nose tended to drop regardless of how fast or slow the engine revolutions were. He also found that even with the nose down, the Shinden still flew horizontally with a level track and slight application of the rudder.
The engineers promised they could fix these issues and the 45 minute (total flight time test of all three flights) test flights were considered a success. I did find a site that has a post in a thread that supposedly are the notes Miyaishi recorded.
<1st test flying> in 3rd Augst 1945
Body conditions
Loading goods : Front opportunity gun (dummy) 2
Weight
Fuel (internal) : 38L
Lubricating oil : 80L
Parachute 1 set
pilot : Yoshitaka Miyaishi (Kyushu Aircraft Co)
-14% ofcenter of gravity position : (It faces an average wing string head.)
main wing Flap : 20°
front wing flap : 26°
Record
Takeoff : Boost +300mmHg
Engine rotation : 2,700 rpm
Exhaust temperature : 650°c
Pipe temperature : 200°c
Oil temperature : 75
Oil pressure : 6
Fuel pressure : 1.6
A raising rudder is taken with takeoff 100 kt in the above conditions, takeoff with speed 105 kt.
Takeoff operation is easy
Rising: Speed 120 kt
Boost +300mmHg
Engine rotation 2,700 rpm
Exhaust temperature 650°c
Pipe temperature 210°c
Oil temperature 87
Oil pressure 6
Fuel pressure 1.7
The right inclination by the propeller torque is very much made high. It can't be modified by the Amendment.
altitude 400m (level flight). .
Speed kt 130 140 130
Boost +300mmHg -100 0 100
Engine rotation rpm 2,400 2,400 2,700
Exhaust temperature c° 700 700 690
Pipe temperature c° 200 220 215
Oil temperature c° 87 87 87
Fuel pressure 1.6 1.7 1.7
Oil pressure 6 6 6
the right inclination by the propeller torque
Landing : gliding speed 130 kt
Landing operation is difficult due to the inclination by the propeller torque
<2nd test flying> in 6th Augst 1945
Body conditions
It is the same as the first flight
Record
Altitude Metre 100 200 300 400 500
Speed kt 120 120 120 135 120
Boost +300mmHg +150 +150 +150 +135 +150
Engine rotation rpm 2,550 2,550 2,550 2,200 2,550
Cowl flap is full open
Exhaust temperature c° 660 660 660
660 660
Pipe temperature c° 215 220 230
220
Oil temperature c° 81 89 93
102 97
Oil pressure 6 5.5 5
4.5-3.9 4.9
Fuel pressure 1.4 1.4 1.4 1.4 1.4
Methanol pressure -3 -3 -3 -3 -3
1.4 1.4 1.4
1.4 1.4
Amendment Full Left Full Left Full Left
Full Left Full Left
Up amendment Full up Full up Full up Full up Full up
The nose falls down though it was amended in the top during the rise.
A body leans to the right though it was amended in full left. The rudder is put, and it is high.
It was full lowered, and it landed with the rudder because the nose was raised suddenly when a rudder was a little raised to the top just before the landing.
Countermeasure
A sleeve is set up in the oil cooler.
<3ed test flying> in 8th Augst 1945
Body conditions
It is the same as the first flight
Record
Take off : 100 kt with the raising rudder
105 kt with front wheel up
110 kt with take off
Boost +300mmHg 2,700 rpm
Rising: Speed 120 kt
Boost +150mmhg
Engine rotation 2,550
Oil pressure 5.5
Fuel pressure 1.3
Exhaust temperature 630c°
Pipe temperature 240c°
Oil temperature 85c°
Inclination 6°
The nose falls down as it becomes low rotation though there is no change in the nose due to the increase and decrease of the engine rotation specially. Altitude 400m
It can fly horizontally if the nose falls down and a rudder is raised if a flap is full raised during the level flight.
Landing gliding speed 130 kt Inclination 3°
Countermeasure
Bigger sleeve is set up in the oil cooler
Main wing falp 30°
Front wing flap is changed to 3°
