Spit/109 sea level speed comparisons in 1.08 beta patch

[klem]

Originally Posted by Kurfürst

That would be an opinion. We need to see a cooling trial to see wheter it's a valid opinion or not. Preferably in a different thread.

5 mins was the instruction in the pilots notes. It did not mean instant failure.

Given that combats usually last only a few minutes it should not be a problem too often. Its true though that information on the maximum time before failure needs to be found or, perhaps more correctly, information that will allow the devs to simulate properly the temperature effects of BCO and then, presumably, the temperature effects on the engine will already have been modelled....... ermmmm I say the latter with my tongue in my cheek.

[Kurfürst]

Originally Posted by klem

5 mins was the instruction in the pilots notes. It did not mean instant failure.

I was more reflecting to the (baseless) part of the claim, that "Merlin engines should not overheat within 5 minutes"

Actually they can, like any other engine, depending on conditions.

The manual says that if possible, the pilot should not operate the engine for more than five minutes at + 6.25 (+12) boost / 3000 rpm, AND that the maximum oil and coolant (iirc 125 degrees Celsius) temperatures during that period are NOT to be exceeded. The overstepping five minutes is less a problem, it will wear out the engine quicker for sure, but temperatures will kill it much quicker. If you run the engine coolant/oil at 160 degrees Celsius it will fail anyway, and I would say, likely well before 5 minutes.

Given that combats usually last only a few minutes it should not be a problem too often. Its true though that information on the maximum time before failure needs to be found or, perhaps more correctly, information that will allow the devs to simulate properly the temperature effects of BCO and then, presumably, the temperature effects on the engine will already have been modelled....... ermmmm I say the latter with my tongue in my cheek.

I agree.

[ATAG_Snapper]

The Merlin engines in the Spitfire MK 1a 100 octane die at 97 C oil temp for all boost and rpms settings in beta 1.08.

[NZtyphoon]

Originally Posted by ATAG_Snapper

The Merlin engines in the Spitfire MK 1a 100 octane die at 97 C oil temp for all boost and rpms settings in beta 1.08.

Merlin II & III Temperatures: Oil = 90-95°, coolant <90° and 120° emergency maximum for five minutes.

Originally Posted by Ze-Jamz

The effect you get from execissve use at certain instances of Boost is not the same as cooking your engine throuh heat, I'm not sure what damage is modeled in game but you suffer with lack of power and can't seem to get your rpm as high as normal..can't remember the exact figure as I try not to do it often

Using high boost at low rpm can lead to pre-ignition, although I haven't yet tried it to see what happens in CLOD: the Pilot's Notes General advise raising the rpm before increasing boost and reduce the boost before decreasing rpm to cruising level.

Just looking at ATAG-Dutch's demo the rpm doesn't seem to go above 1,600 in two tests 130-440 mph...hmmm.

[Osprey]

Regarding the comment on relative difficulty in operating the 109 WEP vs just leaving the 12lbs 'on' with the Spit, please note that when operating the BCO one has to piddle about with the mixture, which isn't always that easy, or rough running occurs.

Regarding the oil pressure drop causing damage. RR performed tests on this and one Hurricane was subjected to 100 continuous rolls before any signs of damage occurred.

[ATAG_Dutch]

Originally Posted by NZtyphoon

Just looking at ATAG-Dutch's demo the rpm doesn't seem to go above 1,600 in two tests 130-440 mph...hmmm.

Hi Typhoon, the test was conducted with the csp brought back to as close to feathered as possible, plus throttle zero. This was to minimize the other drag effects other than the radiator. Trims were not altogether uniform in the three runs either. However, in a vertical dive, gravity assisted only, the radiator shutter caused a full 3 second discrepancy from minimum time at 50% rad and maximum time at 100%.

I'll happily upload the mission I did this with in FMB if anyone would like to carry out the test themselves. The times in 100ths of a second were from the counter in windows movie-maker. This meant i could measure the time from the frame first 'unpaused' to the ASI hitting 440mph. Well, the next line on the gauge after 420.

[ATAG_Snapper]

On a positive note, losing the rudder far below its rated 450 mph IAS helps reduce the Spitfire's roll rate in a dive. Usually the ailerons and elevator are quick to go as well. Losing the elevator ensures the pilot will not overstrain the airframe even if he hauls back on the control column excessively. The airframe should thus remain relatively intact until impact with the ground. It's all good.