Radiator drag

[IvanK]

I spent most of today in the UK National Archives collecting info. One snippet I came across was Radiator Drag measurements on Hurricane II. Graph below gives an indication of the real world effect of Radiator Drag:

[CaptainDoggles]

Nice find,thanks for sharing.

[Kurfürst]

Thx ivank.

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

II. As per the V15a trials.

the 570 km/h speed was understood with the coolant radiator flaps 1/4 open (radiator flaps in streamlined position) and closed (I guess minimum) oil flaps position.
This was sufficient to maintain a constant, optimal 90° Celsius coolant and 62/82° Celsius oil temperature, at +5 ° Celsius external temperature during level speeds.

Maschine Bf 109 V 15 a D-ITPD W.-Nr. 1774
Motor DB 601 A W.-Nr. 140
Schraube 3 fl. VDM Verstellschraube 9-11081 W.-Nr.17459
Wasserkühler 1/4 geöffnet (Klappe in Straak)
Wassertemperatur konstant = 90°
bei +5° Außenlufttemperatur

Ölkühler Klappe geschlossen
Öltemperatur 62/82°; Öldruck 3,2 kg/cm2
bei +5° Außenlufttemperatur

http://kurfurst.org/Performance_test...w_109V15a.html

III. Somewhat related are the figures for Bf 109 G radiator drag.

It should be noted that the top speed of 109's were understood for a condition where the raditor was very slightly open (1/4 open in 109E, 50 mm open on 109F-K) compared to it's minimum opening position, ie. not 'fully' closed (which I believe was impossible to do on 109E anyway). This was usually referred to as 'schnellflugstellung', ie. fast speed setting. Top speed data refer to this setting.

See: http://kurfurst.org/Performance_test...cton_speed.jpg

CONLCUSION

Therefore, IMHO and based the data in a good and realistic 109E radiator drag setting should look as the following:

Raditor closed: ca. + 5 km/h faster speed (negative drag)
Radiator 1/4 open: no drag = top speed achiavable
radiator 100% open: ca. -35 km/h speed loss at SL, ca. -50 km/h speed loss at 5000m (since drag has greater effect at higher speeds/at full throttle heights)

I am looking forward to see the specs for other aircraft as well.

Picture of 109E coolant radiator in presumably fully open condition.

[camber]

Very Interesting!

One thing I am not sure of, does Hurri "Flap 6 notches open" correspond to fully open? It seems likely.

So converting to kmh, the Hurri is losing around 8kmh to the rads at a middle-low speed (340kmh)

The 109 is losing around 50kmh at a high speed (570kmh).

As form drag is very nonlinear with airspeed (supported by real data above) it would be fantastic to see this modelled. Poodling around with fully open rads would be fine, but it would be very detrimental trying to get fast. Good pilots would be having to perform rad adjustments.

[Crumpp]

One snippet I came across was Radiator Drag measurements on Hurricane II.

Nice, thanks for posting it.

What were the test conditions?

[Osprey]

Are you about to invalidate it with your expert insight?


Remarkable difference between Kurfursts 109 data and the Hurricane. The rads are very different though, the Hurricane is a single rad in the propwash so gets perhaps more airflow than outside the wash I would think??? citation needed....
Plus the 109 has twin rads, are they in the propwash, they are on the edge....

[JG52Uther]

Can you please stop sniping at each other.

[Osprey]

Sorry, I was just trying to save time

[Crumpp]

Sorry, I was just trying to save time

No you were not Osprey. You just don't like the fact I don't agree with you on some things.

Grow up.

First of all, it does not make a bit of difference to "test" something and then completely invalidate the effort because of ignorance.

I am not calling anyone ignorant so don't turn it into that. There is a reason why aeronautical engineering efforts are teams in the real world. There is a lot of details that can bite you.

Now, there are some knowledgeable and experienced people on these boards.

You want the dev's to listen and make your favorite gameshape as easy for you to live out your ace fantasy as possible, right?

1C knows what they are doing in terms of aircraft performance. The fact they have adjusted the FM's once says they are concerned. Now, you are saying after all the time they just spent adjusting things....it is completely wrong. Based on what??

Whines waste time and more importantly money to a company. The people at 1C are paid and the company estabilished the boards to save some of that money by cutting down on the number of wild goose chases they send their people on.

If you want to be listenend too then raise legitimate issues. The first thing is is to determine if there is an issue in the first place.

Aircraft performance is dependant upon conditions. Without the conditions, what IvanK posted is interesting like an art gallery is interesting but not very useful for making any conclusions about specific aircraft performance.

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.

[bongodriver]

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

and the reason we can't enjoy the fruits of your very qualified analysis is because?...............