Quote:
Originally Posted by Seadog
If you read Dowding's memo carefully:
http://www.spitfireperformance.com/dowding.pdf
he discusses a number of scenarios that result in engine oil starvation and/or overheating. The engines were failing, not just from overuse of 12lb/3000rpm but from overheating and lack of oil pressure. Steep climbs damage the engine from overheating, not overboosting. Inverted flying damages the engine from lack of lubrication not overboosting. Dowding memo is pretty clear: keep your gauges in the black! Yes, Dowding states not to use 12lb boost for more than 5 minutes, but the real culprit is overheating and lack of oil pressure. No sane pilot, in a combat situation, say with a 109 on his tail is going to worry about using 12lb/3000rpm for more than 5 minutes, and Dowding's memo is nothing more than a reminder to not use overboost except when really needed. |
I read it, thanks. Sry, this did not convinced me
They would write it if the injury of the bearing would depend on the temperature only. "Be watching the thermometer, and untill not in red, u can make what you want". Unnecessarily would limit their pilots (5 min limit) without reason?
"but the real culprit is overheating and lack of oil pressure." - and the strain of the drive. I believe it you recognise it you too, it takes advantage of everything if you squeeze more strength from the drive. Winch, crank, bearing, axis, gaskets, cooling, lubrication. They call it emergency power (
notleistung in 109) because of this.
"No sane pilot, in a combat situation, say with a 109 on his tail is going to worry about using 12lb/3000rpm for more than 5 minutes" - totally agree
I would not care about it. But the engine from this probably gets ruined yet.
U reach home, or dont, it depends of luck. If u lucky enough, u can show the oil filter to maintenance team, if not... with an airplane less.
The same one is true for the Bf 109 anyway. Invert flying prohibited its oil system, and the increase manifold pressure until time only it may be used (
start und notleistung). It is not linked to the temperature there actually, but this unambiguous. Temperature OR the time a limit defines it, till when it may have been used.
What is interesting yet, and I did not know about the fact that the system of the hydraulic propeller is bound to the engine, not separate system: "loss of engine oil pressure (inverted flight, slow rolls) has an effect on the Rotol aircrew in that baldes return to a fine pitch position". This means that he should lose very much from the performance at this time right?