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

Blackdog_kt · #11 06-21-2011, 06:57 PM

Quote:

Originally Posted by Crumpp

No, at any manifold pressure and rpm setting below the knock limited performance of the fuel, the power will be the same.

Basically at any manifold pressure below +9lbs (limit for 87 Octane) in the Merlin, the power is the same for 87 Octane or 100 Octane fuels.

This

Quote:

Originally Posted by CaptainDoggles

The problem is that people think the higher octane fuels magically give more horsepower when in reality they merely allow the engine to develop higher power at higher manifold pressures without engine knock.

and this.

Quote:

Originally Posted by Seadog

Kinda hard to keep formation if some aircraft are using 87 octane and some 100 octane...

In a Blenheim flying a long range recon or ferry mission (which is the only time they could use the auxiliary tanks) it is quite reasonable that there will be long periods where the expectation of enemy encounters are low, and thus mixing octane types is a reasonable risk. The problem is that it will take many seconds before the change back to 100octane can be made, and during that time overboost will not be available and damage to the engine may result if overboost is applied too soon.

Yes, it's kinda hard. And that's why whenever a squad was stationed on a field with available supplies of 100 octane they used that, when stationed on another one i guess they wouldn't.

The only case where you would have mis-matched fuel types in a single flight is if you diverted to another field using a different octane rating and then taking part in a scramble before going back to your own base.

Even so, maintaining formation is not done on full throttle anyway, so the point is moot. A flight leader will always fly slightly lower power settings than the nominal values for a very simple reason: if you're the first to take-off and start climbing (aka getting into a region of a higher TAS as you go along) it's increasingly harder for the wingmen to keep up with you if you are already running the maximum values.
Another reason is fuel economy, yet another one is that the faster you go the more pronounced any mistake is in station keeping.

Have you ever flown formation to the AI in IL2:1946 with their magic, non-overheating engines? If you did then you know what i'm talking about.

Since the amount of boost and RPM used is what governs produced HP, it's perfectly possible to keep formation even when using different octane rating fuel. The only case where a discrepancy would occur and aircraft would be spaced apart is when going to full power, because a difference in O.R. institutes a difference in what full power is for each aircraft. But then again, this happens in combat where (gasp!) it actually makes sense to loosen and even break up the formation, something the RAF realized early on after incidents where multiple losses were incurred because pilots were more busy keeping a close vic formation than actually splitting up and flying combat properly, so they switched their tactics.

In short, a different O.R. has minimal effect in how you keep formation because formations are not flown at full power.
You think too much in terms of pure numbers and totally sidestep tactical considerations and how a mission profile usually plays out. But then again, you're convinced it's possible to run engines on full WEP all day long, so i'm not surprised.

As for the Blenheim, yes it takes time until the residual fuel is burned up and there might even be a case of air in the lines when switching over from tank to tank, which is why it's standard procedure in many aircraft to turn on the fuel boost pumps whenever changing tanks and keep them running for a short while.

Also, full fuel was not only loaded for ferry flights. It was specifically used for long range raids, like the one on the Cologne power station. I have the actual pilot's manual and the main reason they used 100 octane in the first place was because the aircraft was too heavy to safely get off the ground with a full fuel load without the extra boost.