Radiators open or auto?

Something I've been doing for a while now, is before going to mess around doing hammerheads, tailslides, tailslides with power (not sure if there is a name for it, but the torque makes you spin like a top), deliberate spins, I fully open my oil rad flap, but leave my coolant in auto. The oil is overcooled, but because so, the coolant stays cooler, helping to keep the coolant door closed. Also, I need that cold oil when I'm in a straight vertical climb, plus whatever shenanigans I do at the top of the climb. I can really push it.

@baylor703

 

Try closing the Rad all the way and then open it with 4 x 1 second presses of the Open switch.

 

Fly balls to the wall on the throttle; full WEP @ 2700 RPM.

 

Then IF and whenever the temp appears to be getting at the top end of the Green zone, open the OIL Damper for 5 seconds (which is completely open). Most people don't believe me but you will see that the temp drops rapidly when you do that.

Then you can close the Oil Damper up to keep the drag to a minimal ... however I often leave mine wide open for the duration of a race.

 

Tried the four second method you suggested, and it made all the difference. Even in hot temps above 30C. For simplicity's sake, do you think leaving the oil rad open at all times (aside for warming up oil on cold starts etc) to keep cooler is worth the minimal increase in drag?

Edited November 11, 2018 by baylor703

It is worth testing, as the oil cooler door drag is pretty insignificant compared to the gain.

Ok, did some more testing, mainly for those who may see this thread later and want a place to start. This was all done low, at 6k feet, and with the OIL set to auto. These were the best settings I could get doing combat maneuvers and that I would consider "safe" to set at, including occasional loops. Obviously others may get better settings and you will want to monitor coolant temp, but this is a baseline.

 

0C/32F: WEP, closed coolant rad and then opened for 4 seconds. >10 mins

10C/50F: WEP, closed coolant rad and then opened for 4 seconds.- 6/7 mins

24C/75F: WEP, keep both coolant and oil on auto.- >10 mins

32C/90F: WEP, keep both coolant and oil on auto.- >10 mins

Again, I agree with Shahdoh that the Oil Rad Damper provides Minimal Drag.

In fact, I often just leave it wide open during racing.

Otherwise, during air-to-air or air-to-ground flight, I just leave BOTH Rad and Oil on Auto.

 

IF things start to heat up, I open the Oil all the way (press and hold for 5 seconds).

 

I leave the Rad damper on Auto almost always UNLESS Racing. Then I close it up as much as possible (open for 2 - 6x 1second pushes). 2 probably isn't enough and 6 will cause to much drag. I give you that range for experimentation. My Race Setting is "somewhere between those two figures" !!

 

Dog Fighting and Stunts > Oil open and Rad on Auto OR Rad all the way open ... but then it's too hard to Run Away ... which I often find myself doing ... but I do it well ! LOL

I wonder how much the Meredith effect plays a role in speed here.

 

But the effect is so dynamic with air temp, barometric air pressure, current IAS*, water/oil temps.*, and radiator door openings*, all affecting the results, with * marked aspects dynamically influencing each other, and no way to measure the drag caused by the radiator doors, how far they are opened at any point in time, nor the net results of the effect at any point in time... *ugh* I'm not an aeronautical engineer guys :huh:

I wonder how much the Meredith effect plays a role in speed here.

 

 

 

I once asked the same question and YoYo said it's modeled in game.

I'm not question that it is, only saying that I have no idea how to actually make use of it optimally, bc the variable are so numerous, that it might be impossible to predict what to do to get the best outcome.

Testing for best speeds for the Mustang, I have never been able to prove the Meredith effects occurs, other than to get better speed by reducing the drag from the coolant radiator door by operating it manually while keeping the engine cool enough to run for a good while.

 

From what I have read, it is supposed to be just enough thrust to overcome the initial drag from the radiator to begin with, so we are not talking about anything earth shattering, just a few MPH on the top end, and that I have seen. Meredith effect thrust or reduced drag??? In this case, seems like the same thing.

Well yes, it is floating between thrust and reduced drag. But I thought I did read somewhere that it actually added something like 30 - 40 MPH compared to the speeds the 51 would reach if the radiators were simply hanging out in the air I guess.

 

I think you'd need like a bank of NACA slide-rule jockeys to tell you what to set what to for and given situation. Honestly, while I'm flying in combat, my thoughts are with if I'm keeping my engine cool enough to get me through the fight, and not if I might grab another 3 MPH if I closed the oil radiator door just a bit.

I think you'd need like a bank of NACA slide-rule jockeys to tell you what to set what to for and given situation. Honestly, while I'm flying in combat, my thoughts are with if I'm keeping my engine cool enough to get me through the fight, and not if I might grab another 3 MPH if I closed the oil radiator door just a bit.

 

Very true, but it is also nice to know that that extra speed is available when you might need it and able to take advantage of it! And as far as reduced drag airspeed increase, it is considerably more than 3 mph.

 

Will try to get some video of the speed differences later on today.

keystrokes for radiator

 

Need the keystrokes for just manual open and close the radiator. I realize it takes 20 seconds hold to fully do but the keystrokes I was doing sometimes worked sometimes didn't. Thanks

They don't just set it fully open or closed.

 

It's a momentary switch that operates the motor in one of two directions that will open and close the rad door. From full open to full close and vice versa is 20s.

Curious how many of you guys fly the 51 with the rads full open instead of Auto? Do you guys see any benefits to one vs the other?

Sent from my iPhone using Tapatalk Pro

 

 

Might have played with it once or twice.

No reason to use it on anything except auto, since you're busy flying the plane and have other things to concern yourself with :)

 

The auto radiator control is a type of thermostat. If the engine runs a bit warm, it opens the door allowing more cooling air through. When the engine cools down a little, it closes the door. So, the engine temperature is regulated. No need to muck around with it.

 

AD

Might have played with it once or twice.

No reason to use it on anything except auto, since you're busy flying the plane and have other things to concern yourself with :)

 

The auto radiator control is a type of thermostat. If the engine runs a bit warm, it opens the door allowing more cooling air through. When the engine cools down a little, it closes the door. So, the engine temperature is regulated. No need to muck around with it.

 

AD

Except it does it's job poorly on the extremes, or I find it is useful to go to manual and precool the engine before getting into combat. Gives me a some cushion to firewall the aircraft into climbs more

It is just better for p-51 to use its exeptional energy retention.

Just keep 46"/2700 set radiators in to AUTO so it will close radiator flaps at high speeds most likely and use the energy of this plane.

Keeping radiators full open is absolutely pointless, it adds a lot of drag slowing you way down, changing good fighter in to flying brick.

So with radiator flaps full open you will have to be on much higher power settings than when using Auto to get same speed.

If you expecting to rapidly loose air speed you can open radiatos manualy just before it happen or while its happening, but flying full open all the time absolutely pointless,

All the time, yes. But manually opening them is best for specific situations, like my example, where climbing comes in. Climb out off of the ground as well.

Except it does it's job poorly on the extremes, or I find it is useful to go to manual and precool the engine before getting into combat. Gives me a some cushion to firewall the aircraft into climbs more

 

 

I don't see why there should be any problem. When the engine is running at the higher end of its normal (continuous) temperature range, the radiator should be open all the way. At the lower end of the normal range, it should close fully.

 

 

AD

I don't see why there should be any problem. When the engine is running at the higher end of its normal (continuous) temperature range, the radiator should be open all the way. At the lower end of the normal range, it should close fully.

 

 

AD

That's what one would think, but it's not the way of the DCS one. Manually opening them fully gives some extra cooling somehow. This is one of those things that I hope will be touched on when the thermodynamics are redone for the piston engines in 2024, '25, '26...

All the time, yes. But manually opening them is best for specific situations, like my example, where climbing comes in. Climb out off of the ground as well.

 

steady climb you can do at auto position it will give you better climb rate anyway than full open,

i tried both climbs 61 and 67" 3000 rpm at auto works just fine. (from SL to 35k ft w/o any break just throttle w/o all the time)

Auto position will open fully i tested it but it will do only to prevent exceeding temp limits if you want to be in green zone use manual.

I set map with max possible temp i took off and auto totally managed flaps opening them fully once i got some speed it started closing giving me a little more speed.(For t/o i opened coolant door full, during take off coolant doors actuators are lagging hard time, if i would take off with Auto position coolant temp would hit 150 C before coolant flaps would start moving :P coolant temp is changing way to fast i think)

Problem is that those flaps actuators are way to slow to react properly on temp changes so when you make rapid dive you are over cooling and when you go into rapid climb you are overheating but only because actuators are slow as hell compare to rapid temp movement.So i would guess that temps in DCS are traveling too fast or actuators are too slow, for me this problem would be fixed pretty easy IRL if it would accrue.

Auto got bad reputation because ppl often miss concept of this position, they think that Auto=Temps in green this is WRONG!! Auto= Best performance so Highest temps possible.

Edited October 21, 2019 by grafspee

Auto is NOT best performance.

Auto is NOT best performance.

 

Best preformance with small marging of safety

You cant sit at 121 C it is too close to max temp so Auto will try to lower this temp if possible to safe level like 115 or something like that.

Edited October 22, 2019 by grafspee

"Best Performance" is to run as fast as possible and start with 4s open (close fully, then hold open for a 4 count) and adjust open/close with speed. Open when you go slow, close when you go fast. PLAN AHEAD... It's super slow. 20s opened to closed.

 

All that said... The Mustang isn't really a turn fighter so... auto generally works fine if you keep your speed up. Just don't consider that as "best performance" because it isn't.

"Best preformance with small marging of safety"

 

Yes :)

I have to say, with testing the last few days the auto function works much better on all warbirds that use it these days. As compared to six months ago. For instance in the spit and mustang I have not had to use manual radiator cooling in dog fights as compared to six ish months ago it was required or engine overheat and die..

 

My observations