Radiator Effectiveness loss with Overheat in Bf109G-2/F-4, LaGG-3 and Yak-1

[6./ZG26_Klaus_Mann]

Since Water-cooled aircraft loose fluids when Overheating, apparently the radiators become less effective, requiring larger radiator openings in level flight.

I was interested in how severe this effect was in the most important types ingame. And you can partake in it. This is what I do, you should too.

 

 

In the Bf109s first set up a control speed with automatic radiators. Note the approximate radiator opening and Top Speed. Then time 30 seconds of Overheat at full throttle by using manual radiators at 0%. To check the effect just after 30 seconds pass go to 0% throttle and automatic radiators (they will open 100% until acceptable temparature is reached). Then do a second speed run and note down the results again. Repeat the Overheat run on the same aircraft, and note the results. Repeat until 100% radiator openings do no longer suffice to keep the engine temperature at acceptable level. Always note your results. Do not change the trim settings you use, since they have an effect on the top speed.

 

 

In the Klimov Powered aircraft set a top speed and temperatures at 50% radiator opening. This is your control. Overheat conditions in both can be achieved by fully closing the radiators in level flight. Overheat for 30 seconds, then throttle down to 0% and open radiators fully until the engine has cooled down sufficiently. Then do a second speed run with 50% radiators, note down the temperatures again. Top Speed shouldn't have changed, however temperatures should be higher. In case you overheat on the first test already, increase radiator openings in 25% steps, note temperature AND radiator setting. Keep in mind that the fewer variables you change, the more significant the results. I'll post my results below.

Edited December 15, 2015 by 6./ZG26_Klaus_Mann

[6./ZG26_Klaus_Mann]

Bf109G-2:

Control: Speed: 516-518 kph

            Radiators: 30-33%

Test 1: Speed: 517 kph

          Radiators: 33%

Test 2: Speed: 514 kph

          Radiators: 36-40%

Test 3: Speed: 507

          Radiators: 50%

Test 4: Speed: 491

          Radiators: 83%

Test 5: Speed: 482 (Engine damage after 2 minutes)

          Radiators: 100% and constant overheat

 

Conclusion: 1 Minute of Overheat has a marginal effect on performance

2 Minutes are the safe limit.

[6./ZG26_Klaus_Mann]

Yakovlev Yak-1:

 

Control: Speed: 515

            Oil: 105

            Water: 110

 

Test 1: Radiators: 75%

          Oil: 102,5

          Water: 107,5

          Speed: 509

 

Test 2: Radiators: 100%

Critical Temperatures were reached at 900mbar and 2300 RPM

Engine was critically damaged.

 

Sidenote: First Overheats took 15 seconds longer than Bf109G-2

 

Test 2 repeated: Radiators 100%

                        Oil: 105

                        Water: 112,5

                        Speed: 503

 

3rd Overheat very quickly killed the engine.

 

Conclusion: Safe Overheat for no longer than 30 seconds.

Edited December 15, 2015 by 6./ZG26_Klaus_Mann

[6./ZG26_Klaus_Mann]

Bf109F-4

Control: Speed: 518

            Rads: 33%

Test 1: Speed: 500

           Rads: 63

Test 2: Engine failure:

 

However: The Engine took insanely long to overheat meassage in level flight. It will endure high speed level flight with closed radiators longer than Bf109G-2 and Yak-1.