[ACE-OF-ACES]

I see these charts posted a lot, but i don't get how to actually read them can someone please explain?

Well say you want to know what the top speed is at 15kft..

Place your finger on the LHS where it says 1.5 (that is 15,000ft), ie the Y axis (Altitude)

Than drag your finger to the RIGHT until it intesects one of the lines

For example the green one (P-47D-27)

Once your finger intersects the green line

Start moving your finger DOWN until you hit the X axis (TAS)

Under your finger is the SPEED at that alt, ie 15kft

Which looking at the graph is ~395mph