Radiator drag

[phoenix1963]

Originally Posted by Crumpp

1. Determine the atmospheric conditions in the game- that is the first priority. If it is not correct, anything else is a pointless waste of time.

What twaddle, Crumpp you need to distinguish between first and second order effects. Some simple corrections for the "actual" CloD atmosphere are not difficult. Some slight error in a model based on this data would have negligible effect on overall peformance in the scheme of things.

What is lovely about this is some REAL data on a small part of the contribution to performance. However it looks like the data in (winter?) temperate climes has been extrapolated to others, maybe a prediction for overseas performance. Perhaps the basis for a sensible extrapolation to other altitudes in the CloD models.

The very fact that it's labelled "temperate" should suggest to you that small variations in temperature are a fairly minor effect on drag due to the radiator, compared to overall drag - a second order effect.

Get a grip on what is and isn't important!

56RAF_phoenix

[Crumpp]

The very fact that it's labelled "temperate" should suggest to you that small variations in temperature are a fairly minor effect on drag due to the radiator, compared to overall drag - a second order effect.

What twaddle?? The only twaddle is people being agressive and running their mouth without facts.

Conditions in England in August are not far from standard depending on the time of day.

http://www.wunderground.com/history/...q_statename=NA

So the graph is meaningless without specific information.

[CaptainDoggles]

Originally Posted by Crumpp

So the graph is meaningless without specific information.

Not sure if I would go that far. The results appear to be parallel, i.e. linearly translated, so it would seem to me that we can conclude that differing conditions do not have a significant effect on radiator drag. The relative difference between Closed and Open 6 Notches remains about 5 mph at approx. 20000 feet in each curve.

What I would like to see is a comparison for different altitudes.

[Crumpp]

109 data.

I. For what it's worth, French trials of 109E suggest the following figures:

http://kurfurst.org/Performance_test...formanceT.html

Bf 109E-3 at 5000m, OPEN radiators, 2400 rpm and 870mm Hg boost: 520 km/h
Bf 109E-3 at 5000m, CLOSED radiators, 2400 rpm and 880mm Hg boost: 570 km/h

If you line up the altitudes and look at the manifold pressures the French recorded, they used higher manifold pressure's when the closed radiator test was conducted.

That means the speed gap between open and closed due to radiator drag is not as wide as their results.

[Crumpp]

What I would like to see is a comparison for different altitudes.

That is what I am looking at but without the conditions, the information is useless.

[Kurfürst]

Originally Posted by Crumpp

If you line up the altitudes and look at the manifold pressures the French recorded, they used higher manifold pressure's when the closed radiator test was conducted.

That means the speed gap between open and closed due to radiator drag is not as wide as their results.

I don't think 10 Hgmm boost difference would change anything. In real life, that's well inside measurement/manufacturing/modelling tolerance.

From the practical standpoint its not too relevant either, since 1/4 open is the speed referenced point, the temperature is stable. Fully open position has only relevance as a speed break or on the ground for example, in prolonged run up.

In short, technically it might not reach up to modern engineering standards, but its more than good enough to model a flightsim with apprx. good values.

[Crumpp]

In real life, that's well inside measurement/manufacturing/modelling tolerance.

I agree it is not going to make much difference. I just noticed it and wanted to point that out.

Fully open position has only relevance as a speed break or on the ground for example, in prolonged run up.

Exactly.

I did not think the overheat modeling was realistic at all. In general these airplanes are designed to fly with radiators closed or in the least drag position (straak) and keep the engine cooled at maximum continuous and below.

It is only in overboost conditions, high density altitude, and stressful operations such as climbing that the engine temperature becomes an issue. I tried the Spitfire Mk I out and it ran at maximum temperatures in level flight in cruise settings.

[pstyle]

Hopefully the mythical patch update will give us some radiator drag modelling.

We red's have been running about with rads wide open for months now, with no effect on airspeed... I think, in the interests of historicity that this should be fixed...

[klem]

Originally Posted by CaptainDoggles

Not sure if I would go that far. The results appear to be parallel, i.e. linearly translated, so it would seem to me that we can conclude that differing conditions do not have a significant effect on radiator drag. The relative difference between Closed and Open 6 Notches remains about 5 mph at approx. 20000 feet in each curve.

What I would like to see is a comparison for different altitudes.

And so we should not start splitting hairs. There are considerably larger incorrect level speed figures in the Hurricane at the moment (nearly 60mph @ 20,000ft?). 5mph might matter in a tail chase but in terms of combat performance it means almost nothing. It may be more significant at lower altitudes though.

[CaptainDoggles]

Agree 100%