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

[Crumpp]

seems like all you needed was a new set of plugs and a ground test to check smooth running when using the 100 too...

You really don't need to do anything to the engine to run 100 Octane fuel. The engine was made for 87 Octane and can run a higher knock limited performance fuel without penalty.

100 Octane has a higher lead content so changing plugs to one that are more resistant to fouling is not a bad idea.

The engine will not see any performance gains of the additional knock limited performance without modification as instructed by RAF. Those instructions to gain that performance benefit represent major modifications and inform when those major modifications where done. Those instructions have been posted ad-nauseum in this thread.

[bongodriver]

Just out of interest...did anyone realise the use of 'boost cut out' is only authorised for use in combat 'if' 100 octane fuel is used?, this shows that 'any' combat report showing the use of boost in combat confirms the use of 100 octane.

[JtD]

The automatic boost control cut out was intended as a emergency measure in case of automatic boost control failure, as 41Sqn_Banks post already indicated. This would be valid independent of fuel used. The procedure would be to cut the throttle, activate the cut out, and reopen throttle until the desired boost is reached. From then on, changes in speed and altitude would cause a change in boost, which could be controlled by change of throttle or engine rpm (supercharger rpm).

The use of as an emergency boost increase was a later practice. However, unless a report makes specific mention of abc failure, there's absolutely no reason to believe it was activated for anything but a 12lbs emergency boost any time 1940 or later.

[bongodriver]

Originally Posted by JtD

The automatic boost control cut out was intended as a emergency measure in case of automatic boost control failure, as 41Sqn_Banks post already indicated. This would be valid independent of fuel used. The procedure would be to cut the throttle, activate the cut out, and reopen throttle until the desired boost is reached. From then on, changes in speed and altitude would cause a change in boost, which could be controlled by change of throttle or engine rpm (supercharger rpm).

The use of as an emergency boost increase was a later practice. However, unless a report makes specific mention of abc failure, there's absolutely no reason to believe it was activated for anything but a 12lbs emergency boost any time 1940 or later.

This exctract of pilots notes from NZTyphoons post seems explicit on fuel type.

[Crumpp]

The automatic boost control cut out was intended as a emergency measure in case of automatic boost control failure, as 41Sqn_Banks post already indicated. This would be valid independent of fuel used.

The can of worms was openend by the RAF General Pilot's notes authorizing the pilot to have the option to balance his risk.

It's use would also have to be recorded as it would be obvious to anyone who examined the aircraft controls.

There is no way to tell if a pilot using it was linked to fuel.

[NZtyphoon]

Originally Posted by Crumpp

The can of worms was openend by the RAF General Pilot's notes authorizing the pilot to have the option to balance his risk.

It's use would also have to be recorded as it would be obvious to anyone who examined the aircraft controls.

There is no way to tell if a pilot using it was linked to fuel.

So tell us all Crumpp, how did the RAF manage to consume 52,000 gallons of 100 Octane fuel if only a select few frontline fighter units were supposed to use it? Are you going to tell us it wasn't actually consumed but went into and administrative black hole because it wasn't actually 100 octane fuel (recognised because it was green and smelled funny) but converted back to something else and poured back into reserves was it?

What exactly was your explanation and please don't tell me to go back in the thread and look because I know you have never explained this properly.

[JtD]

Originally Posted by bongodriver

This exctract of pilots notes from NZTyphoons post seems explicit on fuel type.

I think this is purpose related - boost control cut out in order to increase performance. The boost control cut out as an emergency item has always been available, at least I haven't seen anything indicating Hurricanes did not have the cut out even when 100 octane fuel wasn't around. The March 39 pilot notes say that "it is intended for use should the automatic boost control fail in flight or should it be necessary in an emergency to override the automatic control for an increase of boost". First purpose would be there even if 87 octane fuel was used. I haven't seen earlier pilot notes.

[bongodriver]

So how exactly does it function? if it's a boost cut out control override how does it help if the boost cut out control has failed, surely a failed ABC is kinda overriden anyway?

[JtD]

I think there's this topic explaining how it works, at least it starts like that.

[41Sqn_Banks]

Originally Posted by bongodriver

So how exactly does it function? if it's a boost cut out control override how does it help if the boost cut out control has failed, surely a failed ABC is kinda overriden anyway?

A failure of the the boost control influences the opening of the throttle valve. Thus the boost can get dangerously low or way to high. The boost control cut-out gives the pilot direct control over the throttle valve.