Hi Wilbus,
>HoHun, I am using Maximum takeoff power. Ki84 with 45/21 engine is 1990 hp. Ki44 HA-109 engine 1520hp.
The way I understood Busa, the Ki-84 is limited to 2900 rpm, +200 mm Hg with both the Homare 12 and the de-rated Homare 21, which seem to have been the only engines fitted to the operational variants. According to the graph Busa posted, that is equivalent to about 1570 HP at sea level, which is what I'm using.
For the Ki-44, I'm using 1355 HP at sea level.
>For my power/weight comparison I use the official numbers with the HA-45-21 engine installed and the HA-109 engine.
Hm, do you have official numbers for the Ha-109? I reverse-engineered the TAIC graph for my numbers, which is not as accurate as numbers straight from the original source.
>With those engines and empty weight the Ki84 holds a slight advantage.
Hm, with my numbers (take-off weight, fully fueled, without external stores) it looks like this:
Ki-84: 3608 kg, 1570 HP - 0.435 HP/kg
Ki-44: 2764 kg, 1355 HP - 0.490 HP/kg
That's a significant advantage for the Ki-44.
>Power of engines is rated as maximum take off power. Can't really compare to different engines at two different altitudes IMO they way you did. Just my opinion though.
Well, I calculated performance over the entire envelope and just provided two cornerstone data points for quick reference. The exact comparison altitude does indeed change the balance between the two aircraft, the Ki-84 benefitting from altitudes greater than 6 km.
Regards,
Henning (HoHun)