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Sources of thrust effectively calculated in BoS FDM....?

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Again, this was something the RAE insisted occurred but no other Aeronautical Research body has been able to reproduce.   No one else at the time that investigated the meredith effect reached the same conclusions and no modern investigation has agreed with their findings either.

Well that may be your opinion. Me, I will continue to trust reports published by the British Aeronautical Research Council unless some proof that they are wrong is presented. :)

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I will continue to trust reports published by the British Aeronautical Research Council

 

You can do that and I notice you are not sharing this report.  Something to hide maybe??

 

Anyway 2 out of three contemporaries disagree with you and all of the modern investigations show otherwise. 

 

On an unrelated note, Why do you have some crap from Kurfurst signature on your signature?  :unsure:

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You can do that and I notice you are not sharing this report.  Something to hide maybe??

Nope, but I quoted the report so you can check for yourself if you think I'm hiding something.

 

On an unrelated note, Why do you have some crap from Kurfurst signature on your signature? :unsure:

 

Background to new sigs here: http://forum.il2sturmovik.com/topic/6830-bf-109-g-2-climb-data/page-2?do=findComment&comment=325785

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LMAO!!!  You really think I care about this childish nonsense?? 

 

 

 

Nope, but I quoted the report so you can check for yourself if you think I'm hiding something.

 

Oh shoot that is different....I mean if you quoted it......

 

:rolleyes:  

 

What a mean to say is that quite often when one sees the facts they are quite different from your conclusions. 

Edited by Crump

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What a mean to say is that quite often when one sees the facts they are quite different from your conclusions.

Finally something we can agree on Crump! We usually have very different interpretations of facts!

 

Now, let's get back on topic shall we?

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Interesting sidenote:

 

Focke Wulf AG did extensive testing to gauge the effect wih their V-18 protoptype, even going as far as adding hot exhaust gasses into the mix to increase possible thrust:

4188ab2fd80261c5fd743f7b3e5cec67.jpg

 

 

Considering no aircraft ended up incorperating the design following these tests I'm thinking the testing established that gains were minimal at best.

Edited by Panthera
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Interesting sidenote:

 

Focke Wulf AG did extensive testing to gauge the effect wih their V-18 protoptype, even going as far as adding hot exhaust gasses into the mix to increase possible thrust

I understood V18 was their testbed for turbocharging, the belly thing being the turbo assembly. Do you have details on the belly cooler (I see a ring cooler in your picture) and what results were achieved?

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I haven't seen that V-18 pic in ages, she's a sexy beast. 

 

The net gains of the Meredith Effect were more significant in terms of reduced radiator drag than they were in actual thrust from what I understand. 

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I haven't seen that V-18 pic in ages, she's a sexy beast. 

 

The net gains of the Meredith Effect were more significant in terms of reduced radiator drag than they were in actual thrust from what I understand. 

 

Everyone else here understands that too I think - no-one on this thread has stated that the system produced net thrust: which is what you mean by "actual thrust" I assume.

 

Jimmy - not specifically aimed at you, just want to lay out my thinking to see if it works....

 

I think of it like this: every component/system in the plane produces a quantity for thrust and drag in a given state of flight. Drag being a force acting against the direction of travel, thrust a force acting in the direction of travel. (Obviously weight and lift can be treated the same way, I will leave them out for this).

 

The net thrust/drag is the result of summing of the forces for each component - and eventually for the whole aeroplane.

 

It just so happens that for nearly all component/systems in an aeroplane, the quantity for the thrust force = zero.

 

If the radiator system is managing to accelerate the cooling air at the outlet, there must be a thrust generated. f=ma [is this correct?]

 

Obviously the radiator system also has a drag quantity - since it is exposed to the airflow this quantity must be greater than zero.

 

So for a radiator system that accelerates air at the outlet, thrust must be greater than zero, and drag must be greater than zero.

 

The questions is,

 

1) What is the value for thrust and drag, and so

2) What is the sum - ie net thrust or drag. 

 

Atwoods article states that the D-T for the P.51 radiator system is low because D is fairly low, and because T is high - specifically that T = 90 when D =100, net system effect D=100-90 = 10. [At fast cruise speeds - just ballpark numbers to illustrate the point].

 

The alternative explanation is that D-T is low because D is so low - T being neglible (or zero). Ie something like D=10-0 = 10

 

Now I am assuming that Atwood's estimate of the net D-T for the system is accurate, and that he knows what the gross drag of the system was ie 100 in my example.

 

So he is saying D=100-90 = 10

 

If someone says that actually it is D=10-0 = 10, then he is not only stating that Atwood was wrong that T in the system is a large quantity compared to D, but you must also be saying that he also did not know the drag of the system in the absence of any thrust. I find that highly implausible.

Edited by unreasonable

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Yeah that's what I meant Unreasonable, please excuse the layman's terms. :) 

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If someone says that actually it is D=10-0 = 10, then he is not only stating that Atwood was wrong that T in the system is a large quantity compared to D, but you must also be saying that he also did not know the drag of the system in the absence of any thrust. I find that highly implausible.

 

You will have to take that up with the majority of the worlds aerodynamic research institutions because they all agree. 

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You will have to take that up with the majority of the worlds aerodynamic research institutions because they all agree. 

 

Agree with what, the assertion that D>T? Yes, no-one here has disputed that. Atwoods's article explicitly states that D>T.

 

They also state that the generation of thrust is real. The only issue is how much. If it is negligible in the P.51 you have to answer the question of how Atwood could be so wrong about not only that value but also the gross drag of his system.

 

Burden of proof lies with you. 

Yeah that's what I meant Unreasonable, please excuse the layman's terms. :)

 

No excuse needed: I am a layman too - just trying to keep the logic clear.

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Burden of proof lies with you. 

 

No, it is already been measured, investigated, and the worlds aerodynamic research institutes agree.

 

 

 

 Our "heat-model" tests rather definitely settled once and for all the doubts and arguments about the Meredith effect.

 

 

http://history.nasa.gov/SP-445/ch5-5.htm

 

i am sorry unreasonable but the facts are the 1940's British engineers are the lone voice in woods once the NACA investigation and German investigations were revealed in the post war.


A radiator simply cannot impart the heat required to produce appreciate amounts of thrust.

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Agree with what, the assertion that D>T? Yes, no-one here has disputed that. Atwoods's article explicitly states that D>T.

 

They also state that the generation of thrust is real. The only issue is how much. If it is negligible in the P.51 you have to answer the question of how Atwood could be so wrong about not only that value but also the gross drag of his system.

 

Burden of proof lies with you.

I suppose it's never going to sink in. But since all the sources agree that thrust is indeed being generated, there's little need to continue the debate.

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Agree with what, the assertion that D>T? Yes, no-one here has disputed that. Atwoods's article explicitly states that D>T.

 

 

Cowards way out btw.  

 

This is not what you state in your second post in this discussion.  You quite blatantly attempt to start a flame war.  You most certainly imply that thrust exceeds drag in the P-51 radiator design.

 

 

I only mention the P51 because, I understand, that it was only with this design that the thrust from the radiators became so significant that it started to disturb previous calculations about top speeds.  But I am sure that you know this already.    Steps aside....

 

 

 

http://forum.il2sturmovik.com/topic/20609-sources-thrust-effectively-calculated-bos-fdm/?p=324590

 

Since that has been disproven you are seeking a more palatable outcome.

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I suppose it's never going to sink in. But since all the sources agree that thrust is indeed being generated, there's little need to continue the debate.

 

Show any measured investigation outside a british wartime one and I will be all over it.

 

That is the rub.  The only actual investigations showed the effect did not exist simply because of the low propulsive efficiency of a radiator.

 

That means a radiator cannot raise the temperature of the air to the point we see net thrust being generated.  

 

Proper inlet sizing, duct design, radiator sizing and outlet design cannot be separated from the "meredith effect" which means the debate rages on in dark corners of aeronautical sciences.  To the vast majority however is a mute discussion and stupid discussion.

 

Design the thing right and it makes no difference what "meredith" says....

 

Take a look at the annual radiator installations and you will see this fact.

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I suppose it's never going to sink in. But since all the sources agree that thrust is indeed being generated, there's little need to continue the debate.

 

I fear you are right - (hint taken I will shut up now... ;)) In a minute....

Edited by unreasonable

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Ring Radiator Installations 

 

Ring radiator installations have shown great promise. The inlet is in the nose of the cowl and can be axisymmetric. Two configurations are shown in Fig. 14, and an internal schematic is given in Fig. 15. The ring radiator offers advantages both from the standpoint of location and of design. Little if any increase in frontal area is required. The inlet design is less aerodynamically complicated, and pressure recovery with minimal losses is relatively easy to achieve. The installation is almost identical to that of radial air-cooled engines in appearance, and the design can benefit from this technology. The Focke-Wulf FW-190 fighter flew with both air-cooled and liquid-cooled engines. The ring radiator was utilized with the liquid-cooled installation. Examples of the ring radiator installation from Ref. 2 are given in Fig. 16.

 

 

 

The report differentiates between a number of different radiator configuration: Wing leading edge, aft win, underslung and annular radiators. The heat recovery effect as it is termed in the paper depends on the power output and speed but is listed as being approximately 4.4% for a 1000 hp installation and 7.4% for a 2000 hp installation. This is then connected to the radiator drag without heat recovery (in drag power percent) and the following figures are listed:

 

Tempest underslung radiator: 15.8%

Tempest annular radiator: 7.3%

Spitfire aft wing: 17.3%

Mosquito wing leading edge: 4.6%

 

http://forum.il2sturmovik.com/topic/20609-sources-thrust-effectively-calculated-bos-fdm/?p=325790

 

Oh crap....

 

No meredith effect there....just really low drag installation....

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Cowards way out btw.  

 

This is not what you state in your second post in this discussion.  You quite blatantly attempt to start a flame war.  You most certainly imply that thrust exceeds drag in the P-51 radiator design.

 

http://forum.il2sturmovik.com/topic/20609-sources-thrust-effectively-calculated-bos-fdm/?p=324590

 

Since that has been disproven you are seeking a more palatable outcome.

 

Classy. The only flame war has come from you - was not me that got the yellow card. (Unless Bearcat was PMing you to meet up for a few beers...)

 

I imply nothing of the kind (that the radiator generates net thrust) - this is your mistaken inference. (Look it up if you do not understand the difference between implication and inference). This would have been obvious to anyone who read the context, from the OP, as being about the analysis of components.  

 

I immediately tried to clear up your misunderstanding. Which is why I posted a long article from a credible source that states that the radiator does indeed generate thrust: just as I said. Of course if you thought that my wording was ambiguous or had the potential for misunderstanding, you could have simply asked for a clarification of what I meant. But no...... endless attacks on a position no-one was taking.

 

Indeed, if someone with credible expertise were to explain to me where I am wrong I will give it due weight. I am perfectly willing to learn from real experts.

 

Not really my place to ask for the thread to be locked, OP's prerogative? 

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Cowards way out btw.  

 

 

 

Completely unnecessary, out of context, indelicate.

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LMAO!!!  You really think I care about this childish nonsense?? 

 

 

You have literarly asked him about it you troll! :big_boss:

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Edited by unreasonable, Today, 16:08.
 

 

 

Mmmmmmmm.....

 

 

 

Completely unnecessary, out of context, indelicate.

 

 

Maybe all of you should have read what was edited out......

 

 

The report differentiates between a number of different radiator configuration: Wing leading edge, aft win, underslung and annular radiators. The heat recovery effect as it is termed in the paper depends on the power output and speed but is listed as being approximately 4.4% for a 1000 hp installation and 7.4% for a 2000 hp installation. This is then connected to the radiator drag without heat recovery (in drag power percent) and the following figures are listed:

 

Tempest underslung radiator: 15.8%

Tempest annular radiator: 7.3%

Spitfire aft wing: 17.3%

Mosquito wing leading edge: 4.6%

 

 

What this really says is what the rest of the world concluded.

 

If you design your inlet, ducting, and outlet correctly....

 

You will only be left with the drag of the moving the radiator thru the air and will not be adding any additional sources due to poor design of the inlet, ducting, and outlet.

 

End of story.

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Mmmmmmmm.....

 

 

 

 

 

Maybe all of you should have read what was edited out......

 

 

 

What this really says is what the rest of the world concluded.

 

If you design your inlet, ducting, and outlet correctly....

 

You will only be left with the drag of the moving the radiator thru the air and will not be adding any additional sources due to poor design of the inlet, ducting, and outlet.

 

End of story.

 

No, I see I have not been clear enough. Let me walk you through it:

 

The report differentiates between a number of different radiator configuration: Wing leading edge, aft win, underslung and annular radiators. The heat recovery effect as it is termed in the paper depends on the power output and speed but is listed as being approximately 4.4% for a 1000 hp installation and 7.4% for a 2000 hp installation. This is then connected to the radiator drag without heat recovery (in drag power percent) and the following figures are listed:

 

Tempest underslung radiator: 15.8%

Tempest annular radiator: 7.3%

Spitfire aft wing: 17.3%

Mosquito wing leading edge: 4.6%

The 4.4 and 7.4% are the heat recovery or Meredith effect. The other figures are the radiator drag WITHOUT heat recovery.

 

So taking the Tempest with annular radiator as example, you cancel out the radiator drag:

 

Radiator drag power Pd=7.3%

 

Meredith thrust power Pt= 7.4%

 

Pt-Pd= 7.4-7.3=0.1%

 

If you do the same calculation for the Mosquito you will see that that there the Meredith effect also cancels out the drag here. However, for the Spitfire this does not happen. It is left with a resulting drag even the Meredith thrust is included.

 

Get it now?

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The other figures are the radiator drag WITHOUT heat recovery.

 

You do not need to "walk me thru it".

 

 

 

The 4.4 and 7.4% are the heat recovery or Meredith effect.

 

Yep, and to the rest of the world it just represents a properl designed inlet, duct, and outlet system.

 

No net thrust produced... 

 

What this really says is what the rest of the world concluded.
 
If you design your inlet, ducting, and outlet correctly....
 
You will only be left with the drag of the moving the radiator thru the air and will not be adding any additional sources due to poor design of the inlet, ducting, and outlet.
 
End of story.

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