Estimating Ki-93 max speed at Sea level (1 Viewer)

From quick search we learn that the Ki-93 was rated to have
2x Mitsubishi Ha-214 (Ha-42-31) Engines

• 2400 hp at 2600 rpm +500 mmHg take-off
• 2000 hp at 2400 rpm +300 mmHg at sea level
• 2130 hp at 2400 rpm +300 mmHg at 1600 m
• 1750 hp at 2400 rpm +300 mmHg at 8300 m

Max Speed of 624km/h at 8300m - 1750hp (+300mmHg)
But this isnt enough info for me. I wanted to know its Sea Level Max Speed with +300mmHg and +500mmHg

I then realised that
J7W1 has
593km/h at Sea Level with 1730hp
741km/h at 8400m with 1660hp
An altitude which is more or less identical to the Ki-93's opt alt where the air drag is the same.
So first I wanted to know how much J7W1 could do at 8400m if it had 1730hp (same as at SL)
1730 / 1660 = 1.0422
Cube Rooted = 1.01386
741 x 1.01386 = 751km/h

This means that when a plane can do 751km/h at 8400m, it will do 593km/h at sea level with the same engine power.
751 / 593 = 1.26644

Now....
Ki-93 has 1750hp at 8300m and 624km/h
624 / 1.26644 = 493km/h at SL with 1750hp

Since Ki-93 has 2000hp at +300mmHg and 2400hp with +500mmHg
More calculations were needed.
2000 / 1750 = 1.14286
Cube Rooted = 1.04552
493 x 1.04552 = 515km/h at SL with 2000hp

2400 / 1750 = 1.37143
Cube Rooted = 1.11103
493 x 1.11103 = 548km/h at SL with 2400hp

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Based on this estimate and this method of working out...

Ki-93
515km/h at SL - 2000hp (+300mmHg)
548km/h at SL - 2400hp (+500mmHg)
624km/h at 8300m - 1750hp (+300mmHg)

Note:
BF-109F-4 has 542km/h at SL at 1.42ata [1350PS]
BF-109G-2 has 546km/h at SL at 1.42ata [1475PS]
BF-109G-6 has 536km/h at SL at 1,42ata [1475PS]

The Japanese built some really sweet looking airplanes.

Was the J7W1 ever tested for maximum speed? I don't believe it was. The J7W1's top speed is synthetically generated and might not be accurate.

AerialTorpedoDude69 said:

Was the J7W1 ever tested for maximum speed? I don't believe it was. The J7W1's top speed is synthetically generated and might not be accurate.

Click to expand...

its not over optimistic
The drag they used for its estimate is barely lower than BF-109's
BF-109K-4 does 603km/h at SL with 2000PS despite not having laminar flow wings.
J7W1 with 2000PS would do 620km/h whilst having laminar wings
-
J7W1 has 20.50m2 wing area and it has Laminar Flow wings
P-51D has 21.65m2 wing area and it has Laminar flow wings

P-51D with 1730hp at SL would do 616km/h
J7W1 with 1730hp at SL does 593km/h