Huricane Mk I 100 Octane perormance tests 1.07.18301

[NZtyphoon]

Originally Posted by Seadog

That's for sure.

However, the main point to this, is that from about 1PM or earlier in the day, is likely have SL temps of ~15c or less. Mean Temps of 19C or higher would be rare and typically restricted to late afternoon. The idea being pushed by the 100 Octane Deniers that English Summer Weather automatically means 19c or higher is nonsense.

And have a look at this Report on London Weather 1940:
July: Cool, with above average rainfall and sunshine.
August:Very dry with above average sunshine and slightly below normal temperatures.
September:Rather cool, dry and sunny.
October:Rather cold with above average rainfall and slightly below normal sunshine.

Cool, slightly below normal temperatures, etc - and London, as a large, urban environment can be approx 2° C warmer than rural areas.

Mind you, that's only talking about temperatures at ground level - the temperatures and pressures can fluctuate at altitude depending on all sorts of conditions - to make a flat statement that performance is conditional on "High density altitude conditions of summer" is a gross over simplification of what can happen in reality.

Britain is an Island, not a large continent like America and its weather patterns are conditioned by the oceanic (Atlantic) climate. So flight conditions over S-E Eng are very different to those over continental America. As an example the 8th AF USAAF found flight conditions in Britain to be very different to those most of its trainee pilots and aircrew had encountered at their American based flight training schools, even during the summers.

Another site on Britain's weather patterns http://www.metlink.org/weather-clima...imate.html#2.1

[Crumpp]

"High density altitude conditions of summer" is a gross over simplification of what can happen in reality.

Wow.........



You guys really believe England meets standard atmospheric conditions for most of the day in August 1940??? Even with the temperature of 15C and 1013Mb?

[Crumpp]

You think England in August has RH = 0???

Come on all you pilots!!!

[IvanK]

Originally Posted by Crumpp

You think England in August has RH = 0???

Come on all you pilots!!!

Goodie Goodie More abbreviations in an attempt to bamboozle the masses.
RH for what its worth is relative Humidity.

As it is I am pretty sure the CLOD atmospheric model doesn't even model "Humidity" per see.

[MiG-3U]

Well, argument on summertime conditions is pretty much pointless.

The FTH depends on pressure altitude so at summertime conditions the FTH for given manifold pressure actually increases in the density altitude scale. In other words, the full 12lbs boost in summertime conditions is available at higher density altitude than at standard conditions.

Physical explanation is fairly simple: The supercharger increases the density in manifolds by keeping the pressure constant up to the FTH. In summertime the warmer air is less dense than in standard conditions so given manifold pressure gives less power than at standard conditions. However, the ability of the supercharger to keep the pressure depends on pressure difference between manifolds and outside atmoshere (plus dynamic pressure) and in summertime the pressure at given density altitude is higher than in standard conditions, hence the FTH increases in the density altitude scale while staying constant at the pressure altitude scale.

All this can be found from the USAF Flight Test Engineering Handbook, available from Scribd:

http://www.scribd.com/doc/19204672/U...ering-Handbook

The problem here is that some members have stated something else and they can't never admit that they were wrong...

[Seadog]

Originally Posted by Crumpp

Wow.........



You guys really believe England meets standard atmospheric conditions for most of the day in August 1940??? Even with the temperature of 15C and 1013Mb?

Manston:
1940 7 19.9 11.8 --- 56.9 (mean daily temp = 15.9C)

What ground temperature would a Luftwaffe raid, arriving over Manston at 8am in mid July 1940, be likely to find?


What ground temperature would they likely encounter over the English Channel?

I have provided the mean high and lows for various locations, and it is pretty obvious that 15C or lower ground temp is a distinct possibility for any likely location, especially before noon, and in the Late (daylight) afternoon (say after 7pm).

[NZtyphoon]

Originally Posted by Crumpp

Wow.........



You guys really believe England meets standard atmospheric conditions for most of the day in August 1940??? Even with the temperature of 15C and 1013Mb?

The usual story, Crumpp thinks he's an expert on British weather conditions during the Battle of Britain, when it has been very carefully explained to him that conditions can be so variable. Flying in Britain - or NZ for that matter - is very different from flying in mid-West America, for very good reasons.

Has Crumpp got any detailed figures for Britain's atmospheric temperatures and pressures at different altitudes during Summer 1940?

[Crumpp]

argument on summertime conditions

In August??

As it is I am pretty sure the CLOD atmospheric model doesn't even model "Humidity" per see.

Probably not and completely irrelevant to the conditions of the Battle of Britain.

[Crumpp]

All this can be found from the USAF Flight Test Engineering Handbook, available from Scribd

Look guy,

The charts are in pressure altitude because the aircraft data is in pressure altitude.

The temperature correction is the density correction.

An engine sees density altitude and your FTH will reflect.

That is not being a "know it all". It is just how it works.

[MiG-3U]

Originally Posted by Crumpp

Look guy,

The charts are in pressure altitude because the aircraft data is in pressure altitude.

The temperature correction is the density correction.

An engine sees density altitude and your FTH will reflect.

That is not being a "know it all". It is just how it works.

The supercharger sees only the pressure and it's ability to compress air depends on pressure difference between atmosphere and manifolds, hence the FTH depends on pressure altitude (plus dynamic pressure). The density inside the manifolds depends on pressure and temperature and that is why power should be corrected with temperature.

Temperature correction does not change the FTH in the pressure altitude scale, only the power at the given pressure altitude. See the example calculations and the graphs and perhaps one day you will understand...

... and then you will state that you have said so right from the beginning