Why didn't the Me 109 get a ventral radiator?

[tomo pauk]

Are talking about a ventral radiator like Bf-109 C ??

View attachment 569288
This radiator was discarded due to big drag obtained, despite of that hot air expelled generated a sustanciable trust.
but the separate under-wing configuration show better performance, with less drag and enough hot air trust, due to so called Meredith effect

The radiator on the picture is providing cooling for a 650-700 HP Jumo 210 engine; it is not vetral radiator, but 'beard radiator'. It will not cool the 1100-1200 HP DB 601A. Radiators on the Bf 109E were so 'good' that by the time 109F emerged they were redesigned, and again redesigned by the time Bf 109G emerged, and still were not as good as on P-51B and later.
BTW - just how draggy was the radiator on Bf 109A to 109D?

 

[Shortround6]

Now perhaps I am missing something but that inlet looks a bit suspect. As does the outlet

to actually use the Meredith you need more than a radiator in a shroud/cowl with an adjustable exit flap.
You need a low drag airflow through the radiator matrix (where the air is heated and expands/rises in pressure) you need an exhaust duct where the air converts in high temperature/pressure to high velocity airflow and you need an exit that matches the exhaust radiator air to the airflow around the exit (or comes close) and you need the exhaust air from the radiator to be around 180 degrees from the direction of travel.
The Mustang probably did the best job at this, The incoming air was expanded and slowed down considerable before it hit the radiator matrix, if you double the speed of the airflow through the matrix you get 4 times the drag.
I see no large increase in the cross section of the early Bf 109 radiator duct that would slow the cooling air down. I also do not see any large area or distance behind what I think is the radiator for the heated air to be compressed/accelerated up to aircraft speed. In fact it appears that air flowing through the top of the radiator matrix has to make some rather severe changes in direction to get out of that slot/hole in the bottom of the aircraft, Even if that flap is closed at high speed and flush with bottom of the fuselage leaving just a slot the exiting air is at angle to direction of travel of the aircraft and smoe of whatever thrust there maybe is lost due to vectors.

The Meredith effect was simple in concept, it was a harder to pull off in practice.

I could be wrong but I would like to see some sort of report/article on the 109s radiator/cooling system/s before I buy into the 109B-D using the Meredith effect.

 

[taly01]

Wings are for lift, radiators are for cooling. Hanging some radiators on the wings cannot have done much for the wings efficiency.

But Messerschmitt and Supermarine knows more than me!

 

[pbehn]

Wings are for lift, radiators are for cooling. Hanging some radiators on the wings cannot have done much for the wings efficiency.

But Messerschmitt and Supermarine knows more than me!

As originally designed the Spitfire would have had evaporative cooling in the wing leading edges, the radiators were added later.

 

[tomo pauk]

...
The Meredith effect was simple in concept, it was a harder to pull off in practice.

I could be wrong but I would like to see some sort of report/article on the 109s radiator/cooling system/s before I buy into the 109B-D using the Meredith effect.

1st sentence quoted is right on the money - just that some designer claimed: 'look, I have radiators with Merredith effect on the aircraft I've designed' does not mean the whole cooling system all of the sudden became zero-drag item.
We do know that radiators on the Bf 109E left a lot to be desired, from sucking in the boundary layer to the exit louvre became draggy when lowered; radiators were redesigned already with 109F series. So yes, the radiators on Bf 109A-D might as well lack finesse, but a switch to double the number of radiators of dubious stremlining on the 109E was not a step in reducing the cooling drag.

 

[Shortround6]

So yes, the radiators on Bf 109A-D might as well lack finesse, but a switch to double the number of radiators of dubious stremlining on the 109E was not a step in reducing the cooling drag

Well, can you imagine a chin radiator of the 109B-D type scaled up to handle 1100hp?

50-57% larger?

 

[tomo pauk]

Well, can you imagine a chin radiator of the 109B-D type scaled up to handle 1100hp?

50-57% larger?

On Bf 109E, a 'beard' radiator will not work due to the CoG reasons anyway?

 

[Shortround6]

Quite possibly, I am sure moving the radiators to the rear of the wing helped.

 

[dedalos]

In August 1944 ,just before the K series entered production, additional aerodynamics improvements were suggested. None was introduced , in order to not interrupt production too much. To be fair, even if the improvements were accepted, i doubt that would be possible to modify the production lines that late in the war. For the underbelly radiator an increase of 15km/h was calculated and rejected as too little. I say a series of small improvements make a big one.
But propably the best solution would be an annular radiator, idealy with an aftercooler, remove the mg 131s for aerodynanic and cog reasons, use belt fed mg ff in the wings, and if possible add small unarmored fuel cells, in the place of the old wing mounted radiators. But such changes would be possible only midwar

 

[tomo pauk]

In August 1944 ,just before the K series entered production, additional aerodynamics improvements were suggested. None was introduced , in order to not interrupt production too much. To be fair, even if the improvements were accepted, i doubt that would be possible to modify the production lines that late in the war. For the underbelly radiator an increase of 15km/h was calculated and rejected as too little. I say a series of small improvements make a big one.

Aerodynamic improvements were (re)introduced with K series, like for example wheel wells covers, retractable tailwheel and more streamlined HMG installation. On same engine, the 109K-4 was 20+ km/h faster than 109G-10.

But propably the best solution would be an annular radiator, idealy with an aftercooler, remove the mg 131s for aerodynanic and cog reasons, use belt fed mg ff in the wings, and if possible add small unarmored fuel cells, in the place of the old wing mounted radiators. But such changes would be possible only midwar

I certainly agree with suggestion of annular radiator, introduction of intercooler (especially for the DB 605AS and D engines) and deletion of HMG installation in favor of the belt-fed MG FFM.

 

[wuzak]

As originally designed the Spitfire would have had evaporative cooling in the wing leading edges, the radiators were added later.

Was that not for the Type 224 Spitfire (with Rolls-Royce Goshawk) rather than the Type 300 Spitfire (with Merlin)?

 

[pbehn]

Was that not for the Type 224 Spitfire (with Rolls-Royce Goshawk) rather than the Type 300 Spitfire (with Merlin)?

As far as I know what became the leading edge fuel tanks were originally supposed to be part of the evaporative cooling system obviously changed early on in the design.
edit
Ahead of the spar, the thick-skinned leading edge of the wing formed a strong and rigid D-shaped box, which took most of the wing loads. At the time the wing was designed, this D-shaped leading edge was intended to house steam condensers for the evaporative cooling system intended for the PV-XII. Constant problems with the evaporative system in the Goshawk led to the adoption of a cooling system which used 100% glycol. The radiators were housed in a new radiator-duct designed by Fredrick Meredith of the RAE at Farnborough; this used the cooling air to generate thrust, greatly reducing the net drag produced by the radiators. In turn, the leading-edge structure lost its function as a condenser, but it was later adapted to house integral fuel tanks of various sizes. from here Spitfire - Design - Elliptical Wing Design

 

[Denniss]

What the heck should they do with a MG FF as wing gun if they had the far better MG 151?
The streamlined HMG installation (in fact just an enlarged/modifed engine cover) was already introduced with AS-engined G-5/-6

 

[tomo pauk]

What the heck should they do with a MG FF as wing gun if they had the far better MG 151?

MG 151 won't fit in the wing of Bf 109 unless the wing got a major change of it's internals, like the Spaninsh did on their Buchons.

The streamlined HMG installation (in fact just an enlarged/modifed engine cover) was already introduced with AS-engined G-5/-6

Indeed, you're right.
OTOH - the G-10 was still with bulges, probably not all the factories introduced the stremlined HMG installation?

 

[Otto_+]

Spoiler: you said this

View attachment 569322

Now perhaps I am missing something but that inlet looks a bit suspect. As does the outlet
View attachment 569323

to actually use the Meredith you need more than a radiator in a shroud/cowl with an adjustable exit flap.
You need a low drag airflow through the radiator matrix (where the air is heated and expands/rises in pressure) you need an exhaust duct where the air converts in high temperature/pressure to high velocity airflow and you need an exit that matches the exhaust radiator air to the airflow around the exit (or comes close) and you need the exhaust air from the radiator to be around 180 degrees from the direction of travel.
The Mustang probably did the best job at this, The incoming air was expanded and slowed down considerable before it hit the radiator matrix, if you double the speed of the airflow through the matrix you get 4 times the drag.
I see no large increase in the cross section of the early Bf 109 radiator duct that would slow the cooling air down. I also do not see any large area or distance behind what I think is the radiator for the heated air to be compressed/accelerated up to aircraft speed. In fact it appears that air flowing through the top of the radiator matrix has to make some rather severe changes in direction to get out of that slot/hole in the bottom of the aircraft, Even if that flap is closed at high speed and flush with bottom of the fuselage leaving just a slot the exiting air is at angle to direction of travel of the aircraft and smoe of whatever thrust there maybe is lost due to vectors.

The Meredith effect was simple in concept, it was a harder to pull off in practice.

I could be wrong but I would like to see some sort of report/article on the 109s radiator/cooling system/s before I buy into the 109B-D using the Meredith effect.

Aaaand here it is !!
THE MEREDITH RAMJET: AN EFFICIENT WAY TO RECOVER THE HEAT WASTED IN PISTON ENGINE COOLING

"" CONCLUSIONS :
The additional thrust of the cooling system further increases the interest for piston engines propulsion in aeronautical field. In fact, due to the Meredith effect, it has been possible to eliminate the radiator drag and to increase the total thrust of the power-pack. Therefore, Meredith ramjet improves the total available thrust and reduces fuel consumption. Both under-fuselage/under nacelle and in-wing configurations were analyzed. In order to reduce the external drag of the duct and to improve lift at take off the in-wing solution with its low aspect ratio radiators seems to be the best choice. ""

 

[tomo pauk]

Aaaand here it is !!

And here it is not.
Author does not make a distinction between radiators of P-51, P-51A, and P-51B-K - yes, three different radiators, each with different intake. He also puts the radiators of Bf 109E with 109F and 109G/K - again, three different radiators. Novere he does mention that 109E was without any form of control or avoidance of boundary layer being flown into radiators, nor he does mention that 109G radiators dispensed with the boundary layer tunnel that is found on the 109F - was it because Germans figured out that boundary layer tunnel offered no actual advantage?
Furthermore - lumping all of radiator systems from 3 different aircraft, totaling to at least 8 different radiator set-ups into one formula, and applying same conclusion??
Shortround6 specifically stated that he does not buy 'into the 109B-D using the Meredith effect', and those marks were not discussed in the article in the 1st place.

 

[Otto_+]

And here it is not.
Author does not make a distinction between radiators of P-51, P-51A, and P-51B-K - yes, three different radiators, each with different intake. He also puts the radiators of Bf 109E with 109F and 109G/K - again, three different radiators. Novere he does mention that 109E was without any form of control or avoidance of boundary layer being flown into radiators, nor he does mention that 109G radiators dispensed with the boundary layer tunnel that is found on the 109F - was it because Germans figured out that boundary layer tunnel offered no actual advantage?
Furthermore - lumping all of radiator systems from 3 different aircraft, totaling to at least 8 different radiator set-ups into one formula, and applying same conclusion??
Shortround6 specifically stated that he does not buy 'into the 109B-D using the Meredith effect', and those marks were not discussed in the article in the 1st place.

No my friend, ..The article that i've posting before, is generalistic. the author talk about all radiators configurations, from Formula ONE sport cars to WWII airplanes.
The author states that the Bf-109 F-G series, and De Havilland DH.98 Mosquito, both with radiator configuration under the wing-roots, is better in performances, than other configurations under-nose or under-belly, like P-51D. ...Now you can study it, and learn, ...or understand what you want.

 

[tomo pauk]

No my friend, ..The article that i've posting before, is generalistic. the author talk about all radiators configurations, from Formula ONE sport cars to WWII airplanes.
The author states that the Bf-109 F-G series, and De Havilland DH.98 Mosquito, both with radiator configuration under the wing-roots, is better in performances, than other configurations under-nose or under-belly, like P-51D. ...Now you can study it, and learn, ...or understand what you want.

Oh, I understood it very well, hence my comments at the above post, and they still stand. I'll add another thing - Mosquito and Bf 109 F-G didn't have the same radiator configuration.

 

[Otto_+]

Oh, I understood it very well, hence my comments at the above post, and they still stand. I'll add another thing - Mosquito and Bf 109 F-G didn't have the same radiator configuration.

No problem, ..you can write an article well documented, with bibliography, same as the article´s author did, reporting the errors. to ARPN Journal of Engineering and Applied Sciences

 

[tomo pauk]

No problem, ..you can write an article well documented, with bibliography, same as the article´s author did, reporting the errors. to ARPN Journal of Engineering and Applied Sciences

Any article, good or bad, written or not yet, still does not mean that inconsistencies I've pointed out on that article are somhow remedied.
When I write article(s), I don't use myself as source, BTW - not here, nor here for example.