A.P. 129 RAF Flying Training Manual, Part I - Landplanes

[NZtyphoon]

Originally Posted by Seadog

I have to admit that I'm surprised that Crump expresses such faith in RAF and UK technological superiority, especially his belief that the RR Merlin could run at 12lb boost for 5 minutes with 87 octane fuel... As much as Crump might wish for this to be modelled in CloD, I should like to agree with NZtyphoon that the Merlin III required 100 octane fuel when pulling greater than 7lb boost.

However, if one reads the memo carefully, Dowding is referring to running the engine beyond it's oil and coolant limits during climbs and to oil starvation during inverted flight, and running the engine beyond 5 minutes as the major culprits in causing engine damage.

Too right, nor did Dowding waste his time by writing to all frontline fighter pilots telling them to refrain from using boost override or exceeding boost limits for 87 octane fuel - why? - because he knew they were all using 100 Octane and was warning them against overuse of +12 lbs boost, as well as the other limits described by Seadog.

[Crumpp]

"In combat and emergency other considerations may justify the pilot in disregarding these limitations"

The Air Ministry gave license to violate the airworthiness of the aircraft. It is no wonder Dowding was concerned.

And yes, any pilot reading that would understand they do what they must to survive even if it means "disregarding these limitations" published in the Operating Notes.

There is no doubt that RAF pilots used whatever system was available to increase the limitations irregardless of fuel type.

[Crumpp]

Crump expresses such faith in RAF and UK technological superiority

No I think they tore up a lot of engines. In fact, I think it was to the point the Operations and Maintenance Chiefs expressed enough concern for Dowding to do something about it.

[fruitbat]

Originally Posted by Crumpp

No I think they tore up a lot of engines. In fact, I think it was to the point the Operations and Maintenance Chiefs expressed enough concern for Dowding to do something about it.

Speculation, not fact.

[Seadog]

Originally Posted by Crumpp

No I think they tore up a lot of engines. In fact, I think it was to the point the Operations and Maintenance Chiefs expressed enough concern for Dowding to do something about it.

Dowding states that the the EBCO allows for 12lb boost for 5mins. I know you love the RR Merlin but would you really have us believe that this could be done with 87 octane fuel?

[Crumpp]

A override for take-off is linked to extra rich mixture to preventing detonation.

Exactly. It was used to test the engine at altitude during service maintenance.

THAT IS WHY YOU HAVE PILOT ANECDOTES OF FLYING AT +16 LBS ON 87 OCTANE!

If they tested the engine to 10.5lbs then a low engineering safety factor of 1.6 yields 16.8lbs. That pilot who did that was extremely lucky his engine did not destroy itself from detonation.

AIR MINISTRY
Air Publication 129
Revised November 1937
Royal Air Force
FLYING TRAINING MANUAL
Part I - LANDPLANES
Chap. II
Aero-engine speeds and boost pressures
66. (vi).(c). Aircraft should not be flow at the maximum conditions for level flight except in emergency, or when special operational conditions necessitate it.

[fruitbat]

Originally Posted by Crumpp

THAT IS WHY YOU HAVE PILOT ANECDOTES OF FLYING AT +16 LBS ON 87 OCTANE!

Where? Source please.

[Seadog]

Originally Posted by Crumpp

Exactly. It was used to test the engine at altitude during service maintenance.

THAT IS WHY YOU HAVE PILOT ANECDOTES OF FLYING AT +16 LBS ON 87 OCTANE!

If they tested the engine to 10.5lbs then a low engineering safety factor of 1.6 yields 16.8lbs. That pilot who did that was extremely lucky his engine did not destroy itself from detonation.

Weeeeeeeeeeeeee boooom...!

That's the sound of Crump's credibility cratering...

16lb boost with 87 octane...

Crump an RAF fanboy...who knew?

[41Sqn_Banks]

Originally Posted by Crumpp

Exactly. It was used to test the engine at altitude during service maintenance.

As said: There is no "override" for Merlin II/III engines. There is no device for extra rich mixture for take-off. There is only a cut-out to disable the boost control. But this was not used for take-off, as maximum take-off boost is the regular rated boost of +6.25.

THAT IS WHY YOU HAVE PILOT ANECDOTES OF FLYING AT +16 LBS ON 87 OCTANE!

Great, show us the anecdote.

If they tested the engine to 10.5lbs then a low engineering safety factor of 1.6 yields 16.8lbs.

Once again you forgot atmospheric pressure in your calculation.
10.5lbs (+ 15.0) is 100%
16.0lbs (+ 15.0) is 121,56%
This is only a factor of 1.2; a factor of 1.6 would be +25.8lbs (+ 15.0).

Exactly. Only in emergency or special operational conditions the aircraft is flow at the "maximum rpm/boost for level flight" (later called "all out") limits and not above.

[Crumpp]

There is no device for extra rich mixture for take-off.

Read the description in AP129.