Inaccurate performance data for BOB fighters in COD comparing to RL data

[Blackdog_kt]

In regards to the Blenheim, the pilot's notes for the Mk.IV specify use of BOTH 87 and 100 octane fuel.

They wanted extra range so they added two extra fuel tanks (the outboard ones) along with a jettison valve for each one.

This made the aircraft heavier when fully fueled and they needed extra boost to maintain a safe takeoff distance. So they modified the engines to run +9 lbs and installed a boost cut-out.

The extra boost caused detonation so they needed 100 octane, but fighter boys needed it too.

The solution? When loaded for long range, Blenheims used 87 octane fuel in the inboard tanks and 100 octane fuel in the outboard tanks.

Take off was done on 100 octane and +9 lbs, climb was done on 87 octane and +5 lbs (ie, they throttled back and switched tanks right after takeoff), cruise was still on 87 octane with a limit of +3.5 lbs for auto-rich mixture and +1.5 lbs for auto-lean.

The standard operating procedure called for depleting the inboard tanks first because they lacked a jettison valve and their fuel contents couldn't be dumped to lighten up the aircraft in an emergency.

Once the inboard tanks were exhausted they were to fly the rest of the mission on 100 octane from the outboard tanks.

For short range missions they would only load the inboard tanks with 87 octane, because +5 lbs boost was deemed sufficient to takeoff with the reduced fuel load.

At least that's what the Mk.IV pilot's operating handbook states.