P-51 Mustang family aside, any other good implementations of ventral Meredith radiators, or good ways to do it?

[GregP]

I rather like the seup in the Yak-3:

Have seen it up close and it seems to be a decent solution. Same for Yak-9.

 

[drgondog]

I rather like the seup in the Yak-3:

View attachment 742788

Have seen it up close and it seems to be a decent solution. Same for Yak-9.

looks like Hurricane scheme.

 

[tomo pauk]

looks like Hurricane scheme.

Hurricane's radiator was all out, IOW it was not semi-buried like it was the case on Italian (one, two)or Soviet fighters (one, two - Yak-3), or on the Ki-61.
Oil coolers on the Yak-3 are buried in the wing, again no such finesse on Hurricane.

 

[Shortround6]

Hurricane may be getting a bad rap

oil cooler is the circle in the middle. Note the air splitter intake from the fuselage bottom.

MK IIs with the Merlin XX engine changed the radiators and oil cooler around some.
MK IVs fitted wire mesh stone guards across the intake. Something to consider depending on role/location.

 

[drgondog]

Hurricane may be getting a bad rap
View attachment 742803
oil cooler is the circle in the middle. Note the air splitter intake from the fuselage bottom.
View attachment 742804
MK IIs with the Merlin XX engine changed the radiators and oil cooler around some.
MK IVs fitted wire mesh stone guards across the intake. Something to consider depending on role/location.
View attachment 742805

Lacks three features I suggest are required. One, expanding plenum to reduce high velocity air to low velocity input across the radiator face. two - Equally, a plenum that squeezes to hot air exiting the radiator, and three- adjustable scoop to minimize exit area.

 

[pbehn]

Lacks three features I suggest are required. One, expanding plenum to reduce high velocity air to low velocity input across the radiator face. two - Equally, a plenum that squeezes to hot air exiting the radiator, and three- adjustable scoop to minimize exit area.

I agree, but it has them, but nowhere near enough to produce the required effect of "net thrust". To do that it would need to be huge and if mounted externally counter productive, to put it inside as with the P-51 is a whole new plane. The Tornado (vulture engined Typhoon) had a ventral radiator. I have never seen a picture of it but it had issues of all sorts and so they went with a chin radiator, I think it was under the pilot so added to compressibility problems

 

[z42]

I agree, but it has them, but nowhere near enough to produce the required effect of "net thrust". To do that it would need to be huge and if mounted externally counter productive, to put it inside as with the P-51 is a whole new plane. The Tornado (vulture engined Typhoon) had a ventral radiator. I have never seen a picture of it but it had issues of all sorts and so they went with a chin radiator, I think it was under the pilot so added to compressibility problems

Just eyeballing it, it looks more like a Hurricane radiator, just bigger. The expansion/contraction ratios of the ducting don't seem particularly big. Also, the inlet is in line with the wing leading edge, rather than in the high pressure zone under the wing.

 

[tomo pauk]

Hurricane may be getting a bad rap

Whole bulk of both radiators was outside of the airframe, IOW - there was no effort was to blend or bury a good portion of either of the two within the airframe.
Even Spitfire and Bf 109E - never very much praised for the execution of the radiator(s) layout - at least have had half-buried radiators, thus reducing the frontal area and at least attempted to slow the incoming air before it hit the radiator itself.

 

[Shortround6]

Lacks three features I suggest are required. One, expanding plenum to reduce high velocity air to low velocity input across the radiator face. two - Equally, a plenum that squeezes to hot air exiting the radiator, and three- adjustable scoop to minimize exit area.

True but it is not quite as backwards as some people think, especially for 1935-37?
Ki-61 model

It is also missing somethings to get the idea to work. But they are all not the same things. Did have a rear ramp

The 109 was learn as you go

cooling air goes out the trapdoor in the bottom. No room for anything.

Hurricane also changed

The Hurricane shape wasn't enough to get the job done but it was not a simple box under the airplane either. The housing tapered from front to middle and then back in again towards the tail, for external streamlining or interior airflow?

 

[z42]

Also, the inlet is in line with the wing leading edge, rather than in the high pressure zone under the wing.

Forgot to mention, not only do you want the inlet in the high pressure zone under the wing, you also want the outlet in the lower pressure zone well behind the wing.

 

[ThomasP]

re "
The Hurricane shape wasn't enough to get the job done but it was not a simple box under the airplane either. The housing tapered from front to middle and then back in again towards the tail, for external streamlining or interior airflow?"

Both,

 

[MIflyer]

you need a converging plenu and variable opening exit scoop to achieve the jet effect.

Yes, of course you do, otherwise you don't have a nozzle. And you need some kind of automatic control of the outlet to keep from driving the pilot crazy with adjustments. WWII ads bragged about that innovation. I do wonder how that hinged arrangement for the intake worked with the Meredith Effect on the earlist Mustangs.

I recall an episode of Mythbusters in which they attached a number of K-bottles - pressurized gas containers - to a boat and expected it to just zip along when they opened the valves. Uh, no, it barely moved. No wonder; they had no nozzles attached.

When they replaced the leading edge intercoolers with the ones under the front of the engine, P-40 style starting with the P-38J they got too much cooling at high altitudes. This led to the fuel being introduced into the cylinders in liquid form, rather than vaporized, with often catastrophic results. At the 9th PRS in India they blocked part of the fresh air outlet air from the intercooler, thereby reducing cooling airflow. The 9th could do that because given that their mission was almost all high altitude, one setting of the airflow was adequate. Fighter P-38's would have to be equipped adjustable flow control and in fact eventually they did that, using cowl flaps, one more thing for the pilot to have to control. At least they set up the Meredith Effect so to prevent the pilot from having to fool with that.

 

[z42]

High pilot workload was supposedly one of the big drawbacks of the P-38. Not only two engines, but lots of different knobs to tune to make the most out of the engines in any particular situation (including preventing turbo overspeed that could result in sending the turbine blades flying in all kinds of undesirable directions).

 

[z42]

True but it is not quite as backwards as some people think, especially for 1935-37?

The Hurricane shape wasn't enough to get the job done but it was not a simple box under the airplane either. The housing tapered from front to middle and then back in again towards the tail, for external streamlining or interior airflow?

I think the Hurricane radiator can be excused. Keep in mind Hawkers predecessor of the Hurricane was the Fury, a biplane with fixed landing gear. And the Hurricane project was initially called the "monoplane Fury". And indeed introduced 1935-ish(?).

The Tornado prototype with the ventral radiator, perhaps less excusable.

 

[MIflyer]

but lots of different knobs to tune to make the most out of the engines in any particular situation (including preventing turbo overspeed

The only way for the pilot to control the turbos in the P-38 was via the throttle, which had a spring leakage to the turbo control. The later P-38 engines had the boost from the mechanical superchargers increased because of turbos coming apart in the earlier versions, so they needed to slow them down.

Aside from the engine operation the P-38 required the hydraulic system to be turned on and off to be able to work the landing gear and the aileron boost to be turned on and off, since trying to land with it turned on was likely to be disastrous.

 

[keithwwalker]

Too bad the Yak 2/4 series wasn't developed more, the radiators were at the extreme aft of the nacelles, behind the landing gear. A proper Meredith installation would of boosted speed to match the Bf-109E.

Any other twin engined craft use this rear nacelle radiator setup?

Also, did any any radial engined craft generate net thrust?

 

[Snautzer01]

Article explaning meredith effect https://www.supercoolprops.com/home/articles/meredith_effect2.html

 

[drgondog]

Yes, of course you do, otherwise you don't have a nozzle. And you need some kind of automatic control of the outlet to keep from driving the pilot crazy with adjustments. WWII ads bragged about that innovation. I do wonder how that hinged arrangement for the intake worked with the Meredith Effect on the earlist Mustangs.

The automatic control was directed to manage glycol coolant temps between 210-240 degrees F.

The hinged arrangement never achieved fixed inlet standard achieved for A-36 onward. Final choice decided upon by climb requirements for mass flow rate through radiator matrix.

 

[Shortround6]

Too bad the Yak 2/4 series wasn't developed more, the radiators were at the extreme aft of the nacelles, behind the landing gear. A proper Meredith installation would of boosted speed to match the Bf-109E.

Look again at the P-51 setup, as a guess any time the radiator duct is only a few feet long your are not going to get an Meredith effect, the diffuser and nozzle area are too short to function properly.

Also, did any any radial engined craft generate net thrust?

Probably not. You have a bit more twisting and turning (more turbulence) and it helps with thrust if the nozzle/s are pointed 180 degrees to the direction of travel.
The engines on the Do 217 are claimed to given net thrust over and above the power needed to drive the fan/s but they had a more complicated exit area than the Fw 190 help that out.

 

[z42]

Too bad the Yak 2/4 series wasn't developed more, the radiators were at the extreme aft of the nacelles, behind the landing gear. A proper Meredith installation would of boosted speed to match the Bf-109E.

Nice find. (From the picture it seems it had two radiators per nacelle, one on each side.)

But yes, just by eyeballing, it does seem the ducting is too short to make for a really low drag radiator (although having two radiators per nacelle helps somewhat).

Also, did any any radial engined craft generate net thrust?

How do you define cooling drag for a radial? Or to put it another way, how do you separate the drag from the engine installation from the cooling? You can of course use "cold engine, cowl flaps closed" as your baseline, but even so the drag from that is going to be pretty different from a hypothetical streamlined engine installation that wouldn't need to worry about cooling, no?

IOW, it might not be well-defined to compare cooling drag between an inline engined plane and a radial engined one.