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MatuDa
04-27-2004, 06:29 AM
Could someone please explain to me why there are severe penalties in speed when opening radiators in planes that dont have change in aerodynamical profile when opening them?

I am well aware that the airflow going through radiators is slowed down by twists and turns in the cooling system and the radiator itself. My point is the aerodynamics of the plane should be even worse with totally closed radiators since then the air is "pushing against" the plane instead of passing through it at reduced speed. A good example of such a plane is the mustang; Huge scoop under the plane that should actually cause more drag closed than open. Me109 has roughly similar system, the radiator exhausts open only when there is airflow keeping them open, thus NOT causing a dragging turbulence.

There was a thread sometime ago where someone claimed the p51 radiator actually caused thrust. That is wrong of course but my claim is the drag can be smaller with open rads and thus more speed.

Any ideas? At least in the 109 opening rads causes a major speed loss and I doubt the realism of that.

MatuDa
04-27-2004, 06:29 AM
Could someone please explain to me why there are severe penalties in speed when opening radiators in planes that dont have change in aerodynamical profile when opening them?

I am well aware that the airflow going through radiators is slowed down by twists and turns in the cooling system and the radiator itself. My point is the aerodynamics of the plane should be even worse with totally closed radiators since then the air is "pushing against" the plane instead of passing through it at reduced speed. A good example of such a plane is the mustang; Huge scoop under the plane that should actually cause more drag closed than open. Me109 has roughly similar system, the radiator exhausts open only when there is airflow keeping them open, thus NOT causing a dragging turbulence.

There was a thread sometime ago where someone claimed the p51 radiator actually caused thrust. That is wrong of course but my claim is the drag can be smaller with open rads and thus more speed.

Any ideas? At least in the 109 opening rads causes a major speed loss and I doubt the realism of that.

CaptainGelo
04-27-2004, 06:36 AM
pony should get speed boost when u open radiator.....

Plane is 2 slow, guns are too week etc..?Here you go... (http://www.hmp16.com/hotstuff/downloads/Justin%20Timberlake%20-%20Cry%20Me%20A%20River.mp3)
http://img23.photobucket.com/albums/v68/wolf4ever/Animation3.gif
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MatuDa
04-27-2004, 06:59 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by oleg86:
pony should get speed boost when u open radiator.....

Plane is 2 slow, guns are too week etc..?
<HR></BLOCKQUOTE>

Please, if you don't understand what is being said by all means ask. Here's an example: How can guns be too "week"?

As for my original post I'm sure someone can see the logic behind the reasoning? I'd be happy if someone explained the added drag when aerodynamical profile stays (basically) the same.

p1ngu666
04-27-2004, 07:49 AM
radiator might produce thrust but maybe not enough to offset drag.
think its better not to slow down air, but make it go around

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Enofinu
04-27-2004, 08:16 AM
old thread.
all been disussed earlier with Olegs comments.

VW-IceFire
04-27-2004, 08:20 AM
There was one version of FB with radiator drag being too high...I think they fixed that.

It was essentially proven by members of this forum that the real P-51 did not get a speed boost from having its radiator open...it was still causing drag. The advantage to the design was that it still had less drag (and the miniscule extra thrust) than conventional radiator designs making the plane aerodynamically efficient...it didn't mean you opened the radiator to turn on your rocket engine or anything http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

I think they are at the limits of modeling this...but I think radiator drag has been cut down to the average levels for all planes. Its not like what I remember it to be.

I don't even manage it on the P-51 or the Bf 109 (with the auto control system)...on the FW190 I do keep changing settings to match my flight...and with the P-47 I keep it closed till it heats up and then I let her cool off a bit.

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CaptainGelo
04-27-2004, 08:23 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by MatuDa:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by oleg86:
pony should get speed boost when u open radiator.....

Plane is 2 slow, guns are too week etc..?
<HR></BLOCKQUOTE>

Please, if you don't understand what is being said by all means ask. Here's an example: How can guns be too "week"?

As for my original post I'm sure someone can see the logic behind the reasoning? I'd be happy if someone explained the added drag when aerodynamical profile stays (basically) the same.<HR></BLOCKQUOTE>

OPEN your EYES AND USE THEM...ITS A PART OF MY SIGNATURE.....

oh yea and about drag...use your HEAD...

Plane is 2 slow, guns are too weak etc..?Here you go... (http://www.hmp16.com/hotstuff/downloads/Justin%20Timberlake%20-%20Cry%20Me%20A%20River.mp3)
http://img23.photobucket.com/albums/v68/wolf4ever/Animation3.gif
"Big Bills suck, small Bills don't"&lt;----WRONG!!!! all Bills suck http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

CaptainGelo
04-27-2004, 08:40 AM
can u see it now?

'''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''

Plane is 2 slow, guns are too weak etc..?Here you go... (http://www.hmp16.com/hotstuff/downloads/Justin%20Timberlake%20-%20Cry%20Me%20A%20River.mp3)
http://img23.photobucket.com/albums/v68/wolf4ever/Animation3.gif
"Big Bills suck, small Bills don't"&lt;----WRONG!!!! all Bills suck http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

CaptainGelo
04-27-2004, 08:45 AM
test

'''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''

plane is 2slow, guns are 2weak and DM suck? (http://www.hmp16.com/hotstuff/downloads/Justin%20Timberlake%20-%20Cry%20Me%20A%20River.mp3)
http://img23.photobucket.com/albums/v68/wolf4ever/Animation3.gif
"Big Bills suck, small Bills don't"&lt;----WRONG!!!! all Bills suck http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

VMF513_Sandman
04-27-2004, 02:23 PM
seems the p-38 does get faster after it gets warmed up a bit...then again, the allisions were liquid cooled. p-51 in 1.22 did seem to fly extremely fast at full radiator and throttle at 70%, pitch at 100%. i dont fly 109's much to say for sure that radiators fully opened or closed makes much of a difference. if i remember, opening the radiator in the p-40's did create drag if they were open too much...but the 40's also had the allison's..liquid cooling, so they shouldnt(but do in fb) overheat quite fast.

LeadSpitter_
04-27-2004, 05:45 PM
i noticed planes like the 190 it does not effect you much but the p47 you get severly penalized the p40 too, the zero and ki84 can run full open and not get penalized much at all, the mustangs you gain more speed with it open how it should be, seems they reduced drag for only certain aircraft but forgot a bunch

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MatuDa
04-28-2004, 12:14 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by LeadSpitter_:
i noticed planes like the 190 it does not effect you much but the p47 you get severly penalized the p40 too, the zero and ki84 can run full open and not get penalized much at all, the mustangs you gain more speed with it open how it should be, seems they reduced drag for only certain aircraft but forgot a bunch

http://img14.photobucket.com/albums/v43/leadspitter/newsig.jpg <HR></BLOCKQUOTE>

I hope radiator drag gets another check from the devs, especially planes that have basically same aerodynamical form with rads open and closed.

Hunde_3.JG51
04-28-2004, 12:59 AM
LS, I would like to see some proof on that. I did speed tests at sea-level with 190, 109, La-5, and some others and they all lost about 17+km/h with radiator open. I'll test P-47, P-51, & P-40 tomorrow. P-51 shouldn't gain speed with radiator open, this was already refuted by Oleg. I may be wrong but I think radiator drag is pretty similar in all planes. Like I said, I could be wrong.

And feel free to read the "Ta-152" thread on this page as to why I don't think the 190A should suffer much radiator drag at all since the majority of the cooloing was internal, non-adjustable, and present when speed test were performed from the beginning. All of the radiator drag on the FW-190A is induced by the small cooling gills which open up minimally into airflow.

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BigKahuna_GS
04-28-2004, 02:37 AM
S!


Oleg sent me tracks of the P51 at Sea Level and 25,000ft attaining max speed--the radiator was fully closed with throttle 110% & WEP on for both speed runs. Prop was left on auto.

If you are a Mustang driver, it pays to constanly monitor the radiator in manual mode and closed whenever possible leading up to and during a fight. You will gain from 10-20kph more with the radiator closed, retain more "E" and zoom climb slightly higher.

That has been my experience anyways. It seems most planes pay the penalty for opening the radiator, especially the P47 and P40. The plane that does not seem to gain that much with the radiator fully closed is the P38, I am still experimenting with it.


This an old thread subject and Oleg has covered it extensively.

_______________



CCJ: What do you define as the most important things a fighter pilot must know to be successful, relating to air combat maneuvering?

Robert S. Johnson :
It's pretty simple, really. Know the absolute limits of your plane's capabilities.
Know its strengths and weaknesses. Know the strengths and weaknesses of you enemy's fighters. Never fight the way your enemy fights best. Always fight the way you fight best. Never be predictable.

In "Fighter Aces," aviation historians Raymond Tolliver
and Trevor Constable compared Johnson's record with that of two German aces.
Werner Molders was the first ace to score 100 aerial victories and Erich Hartmann is the top scoring ace of all time with 352.

The authors noted that
Johnson "emerges impressively from this comparison." He downed 28 planes in 91 sorties, while Molders took 142 sorties to do the same, and Hartmann, 194.
________



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"Angels of Okinawa"

jurinko
04-28-2004, 04:34 AM
read a book from German fighter from Eastern front, they were chased by Russians and enemies were gaining on him, wtf? then found out the radiator was fully open, closed it and run away from them. It really did some noticeable difference.

---------------------
Letka.13/Liptow @ HL

TgD Thunderbolt56
04-28-2004, 06:47 AM
The physics should be affected like this: If the radiator is closed, then the air intake will be shallow and create a small amount of drag. The air that enters will create a small "air" pillow that creates only minimal drag. Once opened, the conduit of air throughout the intake acts more like a miniature parachute that will induce more drag.

There were a few exceptions to this (i.e. the "compression" that occurs in the P-51 radiator intake that actually adds small amounts of propulsion) and this phenomenon has not only been observed, but applied to some aerodynamic designs in recent history.

This is largely dependent upon the radiator/engine design. Most radial engines have the cowl flaps that are designed to disturb the airflow and redirect it to the radial heads thus providing cooling. Radials, by proxy, SHOULD realize the greatest malevolent affects of opening the radiator/cowl flaps.

I can certainly provide formulae and examples if necessary, though it would require me pulling out my old physics/aerodynamics texts from school.



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Hunde_3.JG51
04-28-2004, 02:03 PM
Unless that radial is a BMW-801. Here are my points:

-BMW-801 was cooled by internal routing and baffles that took air from outside which would cause drag.

-BMW-801 was cooled by a fan that rotated at 3 times the speed of the propeller.

-These were not adjustable.

-This means that any speed results achieved are with these cooling measures in place and active. Essentially the radiator is always open. Early 190's had no cooling gills/slots and as far as I know had no adjustable cooling measures so top speed would be the same no matter what, there was no adjusting anything.

-Even with cooling gills they were very small and opened minimally. But more importantly they were located right behind exhaust stacks and the exhaust/cowling actually came out much farther than gills so they were not really put into airflow (I have a great picture of this but I don't know how to scan in & post pictures http://ubbxforums.ubi.com/infopop/emoticons/icon_frown.gif ). One source even suggests a small amount of thrust was created by gills but I doubt this.

The FW-190 was very unique in its cooling system. The P-47, for example, had large external flaps that opened all around the engine and into airflow.

*As a note the new 190's (with Ash-82) are being made using a cooling fan that only turns at the speed of the propeller, the FW-190's in WWII spun at 3.2 times the speed of the propeller.

A quote.

"Next, the plane was returned to the manufacturer for necessary modifications, especially in the cooling system. In the case of radial engines there was only one possible solution: to increase airflow over the engine. This was done by using a ten blade(later increased to 12 on BMW-801D) fan on the propeller shaft, in front of the engine, near the cowling. The tunnel spinner was replaced by a traditional spinner, covering only the airscrew hub of the VDM metal propeller. It was decided to use this after tunnel trials which had shown that the big spinner had not given proper airflow for efficient engine cooling and its influence on the reduction of pressure drag was not significant. Engine cooling was improved after this modification, but not to the expected level, and the engine still operated in the high range of acceptable temperatures."

Here are two good images showing what I was talking about with gills not really being in airflow and behind exhaust and in from cowling. Also, an imortant point is that the gills were an outlet for hot air, not an intake of any kind.

http://www.ipmsstockholm.org/photos/detail_fw190a_05.jpg

http://www.aircraftresourcecenter.com/AWA1/301-400/walk346/images_Bernie_McKenna/fw190_10.jpg

Compared to the P-47, not the greatest image but it shows what I mean about most other radials having large surfaces extend into airflow. This is what Thunderbolt is talking about.

http://www.il2center.com/Allied/US/09/10.jpg

Looking at these pics I don't see how the FW-190A suffers from any real drag at all. Yes there is drag coming into engine (as with all radials) but it was always there and speeds obtained were done with this in place from the beginning. FW-190 also has unique cooling system with internal baffles and cooling fan. While others have external surfaces extending into airflow while the 190 has none. The 190's cooling was considered "ingenious" after the war for a reason, because it allowed an extremely neat engine/cowling design with no external surfaces protruding. But it certainly had its problems early on.

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Formerly Kyrule2
http://www.jg51.com/

[This message was edited by Hunde_3.JG51 on Wed April 28 2004 at 01:34 PM.]

p1ngu666
04-28-2004, 04:06 PM
hunde, to play devils advicate... http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif
the drag is mainly thru the rad/fins on radials
those lil slats and pretty well placed, judging by eye and current f1 cars http://ubbxforums.ubi.com/images/smiley/16x16_smiley-surprised.gif
tiny slits tho, compared to other aircraft :O
the exit air will be going faster than intake air, this may or may not give thrust/drag,
when gills closed, like in first pic u get a solid object effect i think, hence less drag http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif
surprising exit area difference on jug/190
jug flaps could be in a low pressure zone also

sometimes i wish i had a wind tunnel http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

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