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

spicmart said:

The ventral radiator placement in many WW2 fighters was supposed to be less draggy than underwing radiators afaik? So why wasn't that changed with the Me 109?
Examples were the series 5 Italian fighters, the Ki-61 and the Yaks.

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Up until the Me 109D the Jumo 210 engined Me 109 versions had a chin ventral radiator. The 109E introduced the twin wing radiators but the oil cooler stayed in the chin position. The Me 109E radiators were sophisticated and recovered heat as thrust. A split flap arrangement controlled airflow with the normal split flap forming the lower part of the nozzle and the upper being it's own flap. in the Me 109F a boundary layer splitter was added.

One obvious reason for not having a ventral radiator is not having that position available for a fuel drop tank or bomb.

One doesn't have to write well documented articles , with bibliographies, to be able to understand that the study made no mention of the Bf 109B-D or indeed dozens of other liquid cooled engines/aircraft of the 20s and early to mid 30s. Simply sticking a radiator in a duct doesn't mean it becomes a Meredith ramjet.
try reading the report a little closer.

"The design of the duct proved to be nontrivial and resulted in the first duct to be held away from the fuselage to keep the opening out of the turbulent fuselage boundary layer, which created vibration problems with flush openings."

Nontrivial----- Definition by Merriam Webster= not trivial : significant, important.

In other words, it took a while to get it right (or close to right).

tomo pauk said:

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?

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The Bf 109E had an 1100hp engine. The Me 109F had an 1350hp engine and was a major redesign and the Me 109G/K got to 2000hp with boost levels much higher. One would expect a radiator redesign. Spitfire needed a second radiator added as the two stage merlind and grifone were introduced. P51 received several radiator redesigns.

For the Me 309 Messerschmitt had moved to a ventral radiator which was partially retractable and clearly sophisticated. Angular radiators proved very effective due to the absence of boundary layer problems and the low pressure loss frim the increased area. May have been better than P51.

Koopernic said:

The Bf 109E had an 1100hp engine. The Me 109F had an 1350hp engine and was a major redesign and the Me 109G/K got to 2000hp with boost levels much higher. One would expect a radiator redesign. Spitfire needed a second radiator added as the two stage merlind and grifone were introduced. P51 received several radiator redesigns.

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I know that.
The person that wrote the article I've found fishy does not talk about that at all.

For the Me 309 Messerschmitt had moved to a ventral radiator which was partially retractable and clearly sophisticated. Angular radiators proved very effective due to the absence of boundary layer problems and the low pressure loss frim the increased area. May have been better than P51.

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In this case, a 'clearly sophisticated' raidiator is a bug, bot a feature. In between entence - you're applying too wide a brush.
About the last sentence: I may have the Brooklyn bridge on sale, real cheap.

tomo pauk said:

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.

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I agree, i don't use myself as source when I write an article too, unless the article that i've writing, need sources of data who i've compiled by me in a previous work, but i am not Professor of Industrial Engineering in the Bologna University, as the author of the article about Meredith ramjet effect , that you trying to disqualify.
I think that, everything about me point and doubts, about piston aircrafts radiator efficiency, is explained properly in the article of the Professor Luca Piancastelli.

Otto_+ said:

I agree, i don't use myself as source when I write an article too, unless the article that i've writing, need sources of data who i've compiled by me in a previous work, but i am not Professor of Industrial Engineering in the Bologna University, as the author of the article about Meredith ramjet effect , that you trying to disqualify.

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Unfortunately, my job was made very easy by proffesor himself.

I think that, everything about me point and doubts, about piston aircrafts radiator efficiency, is explained properly in the article of the Professor Luca Piancastelli.

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Link does not work.
OTOH, Hoerner points out that radiators on the Bf 109 (two underwing + one oil cooler) represent a major drag increment: link.