There is no speculation. It is facts. It is not my fault folks do not understand the relationship of humidity to density but only focus on a simplistic picture based on what they have learned on a gaming forum.

Why don't you give some facts instead of emotional appeals. Try reason for a change!!

Ohh yeah, because you can't discredit the information with facts and reason. You have no other recourse than emotional appeals.

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 :)

Ok you are flying at the fth at a given pressure and temp, engine runing at a give rpm.

What would you think if I start to spray (cold) water in the supercharger inlet ?

The relation of perfect gazes work only with gazes in perfetc conditions ;)

Most of the time the variation will be minimal, just like in British summertime for a British engineered plane.

What is utmost funny is that the same guys tell us that changing the type of fuel have no effect at all and the eng will run fine despite the much higher thermal energy that this imply.

:confused:

I am getting confused but I know since long that is what they want. Hence their frenetic charges against who ever get a technical view inappropriate with their.

I repeat, has Crumpp got any detailed information figures for Britain's atmospheric temperatures and pressures at different altitudes during Summer 1940?

Has Crumpp got detailed readings of the relative humidity for each day of summer 1940?

Nor has Crumpp twigged to the fact that Britain has an Oceanic climate, dominated by the Atlantic ocean, which means that atmospheric air temperatures, humidity and pressure are variable and can change quickly, even at the height of summer:

One reason why the USAAF's pilots and aircrews had so much trouble adapting to Britain's weather conditions was because they had trained in the relatively settled climactic conditions experienced on the continental USA, with mostly clear skies, higher average temperatures and lower humidity than anything experienced in Britain.

Making a blanket statement:

Shows a profound ignorance of how the weather conditions in Britain can change rapidly in the space of a few hours, as others, who actually live there and know this, have been trying to tell Crumpp.

No, the engine see density not pressure.

1. Whenever you include temperature, you are really talking about density.


IF the engine is equipped with a density controller. If it has a pressure relief valve, then it is dependent upon density altitude.

If it has an absolute pressure valve or a variable pressure controller then it is subject to density altitude effects.

Well, you are just avoiding the facts here:

1. The engine we are talking here, Merlin (and the US radials in the USAF handbook), keeps constant manifold pressure up to the critical altitude. There are other manifold pressure/density regulating systems but that's another story.

2. The temperature correction does not change the FTH at the pressure altitude scale in these engines. This means that in the density altitude scale the FTH varies according to temperature difference from the standard conditions while the FTH stays constant at the pressure altitude scale.

3. Read the USAF handbook instead waste our time, it's all there. RTFM :)

If you're talking about switching from 87 up to 100 octane, you need to go look at what the definition of an Octane number is. Octane number does not mean the fuel has more energy in it.

Well you are right but you are playing with the words Doggles.

No I'm not playing with the words.

No, You need to read the handbook.

In fact, give Lycoming customer service a call. They will be glad to help you out.

1-570-323-6181