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

[BarnOwlLover]

As far as location, the mounting for the Mustang's radiator, it probably just made the most sense for it to be there. I was even thinking about that for the Spitfire. The late decision (from what I read) to abandon evaporative cooling for the Merlin on the Spitfire to conventional water/glycol/water-glycol blend governed the underwing radiators, as well as the mod having to be a bit of a "rush job".

You do also have to remember that the Supermarine 305 turret fighter had a chin radiator, and the 312 cannon fighter was envisioned to use a ventral radiator.

 

[Admiral Beez]

You could have a Mustang style radiator under each nacelle. But then you have to figure out where to put the main landing gear.

Good points. I now think chin radiators like on the FW-187 would be the best option for the Whirlwind.

Two engines one rad are out, but the Spitfire's two rads one engine is in.

 

[spicmart]

You could have a Mustang style radiator under each nacelle. But then you have to figure out where to put the main landing gear.

It might be possible to retract the landing gear not by retracting it backwards but perpendicular to the engine line with.
If you install such a radiator and its air intake on the side of the nacelle you need not to build it as long as it would be the case when mounting it ventrally.
But you would have to have exhaust stacks which lead away the exhausts from the radiator air intake.
Lke on the Me 110.
In both cases the rear of the nacelles would be quite long.
Maybe even combine the radiator exhaust with turbocharger exhaust if there is one..

 

[BarnOwlLover]

In any case, single or twin engine, you'll need a fair amount of space for a good Meredith radiator. Here's a couple of cutaways of a XP-51G and P-51H (both used a refined version of the P-51B/C/D/K radiator system).

And a couple P-51D for reference.

 

[BarnOwlLover]

Also, the P-51H (and the XP-51F/G) have a longer fuselage than the earlier models. Could that help with refining the radiator shrouding, as well as the F-82?

 

[BarnOwlLover]

Also, I'd like to submit this drawing. Is the radiator installation (this being a 1940 concept illustration) decent, good, or crap?

 

[pbehn]

Also, I'd like to submit this drawing. Is the radiator installation (this being a 1940 concept illustration) decent, good, or crap?

View attachment 697453

Some things are obvious and others arent. There were numerous changes to the Mustang and P-51 radiator system. They all look similar, only their place in the evolution of the plane gives away whether they were improvements or not to anyone who isnt an expert in either aerodynamics or the history of the plane. To me that needs the scoop moving back and the "splitter" increasing in size.

 

[GrauGeist]

It appears to me that the small scoop foreward of the main intake would disrupt the airflow enough that the boundary layer separation would not be the same as the P-51's.

 

[Shortround6]

It is a sketch so we can cut it a bit of slack.
However it does show one of the problems. If you use a short inlet before the air hits the radiator the air going to the top of radiator has to travel considerably further hit the radiator compared to the air hitting the bottom of the radiator and travel considerably further to reach the outlet using a short outlet.
The problem isn't necessarily the distance but the difference in distance which may be sorted out in detail design vs concept sketch.
The greater the difference in the direction the flow takes and the greater the difference in speeds of the airflow in the duct the greater the chances of turbulence in the airflow no matter what was done with boundary layer separation.

Leaving the intake where it is, move the actual radiator back several feet to reduce the angles in the airflow, then add not only the existing outlet but extend it also an additional several feet (you are now just short of the tail wheel) to help straighten out the exit airflow.
Now is that "different" from the sketch or just detail/development?

 

[BarnOwlLover]

I'm guessing it wouldn't be wise to fare the radiator exit into the fuselage (keeping the fuselage taper near constant without the raised area leading from the exit to the tail)?

 

[tomo pauk]

I'm guessing it wouldn't be wise to fare the radiator exit into the fuselage (keeping the fuselage taper near constant without the raised area leading from the exit to the tail)?

Looking much like the rear end of the CASA C-101 or the Pampa?

 

[BarnOwlLover]

What I mean is how much the radiator housing sticks out compared to the rear of the fuselage. I know that was a feature of even the Allison powered versions. But it is necessary to have the tail/rear of the fuselage raised so much in contour compared to the front fuselage's underside?

 

[GrauGeist]

What I mean is how much the radiator housing sticks out compared to the rear of the fuselage. I know that was a feature of even the Allison powered versions. But it is necessary to have the tail/rear of the fuselage raised so much in contour compared to the front fuselage's underside?

A great deal of early aircraft design was really hit or miss.

By the 1930's, aircraft design theory was still an unexplored territory, as powered flight itself was entering it's third decade.

 

[BarnOwlLover]

Though it was never actually built or flown, and I don't believe that any detail design docs exist for it, but what about the Hawker P.1027 project for a Rolls-Royce Eagle powered Tempest that did use a ventral radiator similar to the XP-51F/G and the P-51H and F-82?

Hawker P.1027 and P.1030

In 1943, anticipating the availability of the 3,500-4,020 hp Rolls-Royce Eagle 22 engine, Hawker proposed two new versions of the Tempest with greater cooling capability, the P.1027 with Mustang-like ventral radiator and the P.1030 with leading edge radiators, but no prototypes were ordered...

www.secretprojects.co.uk

Hawker P 1030

Hello Any one can help me please. I'm looking for more precise 3-view drawings and fuselage sections (if it's possible) of the Hawker P 1030 because I want make a radio controled aircraft of this plane. Many thanks

www.secretprojects.co.uk

 

[spicmart]

A Spitfire with full Meredith-effect capability would have been the ultimate fighter of WW2. It was already the supreme dogfighter. Coupled with a speed increase of 40 or 50 km/h it would habe been superior to all other super-props with maybe the exception of the P-51H. Your opinions?

 

[z42]

Slightly reviving this semi-zombie thread..

On the Meredith Effect has links to a number of interesting recent articles about Meredith effect radiators. The target usage is piston powered stratospheric research aircraft/UAV's, which need to fly relatively fast to stay aloft in the thin air. A few brief takeaways (though I recommend anyone interested to read the articles, they are relatively approachable even for a non-aerodynamicist like yours truly) that touch on issues mentioned in this thread:

• Location of the inlet: Ideally you want to place the inlet in the highest pressure region (because higher pressure => smaller radiator and ducting). That's under the wing at about 2/3 chord. Which is about where the P-51 and many other aircraft with ventral radiators placed the inlet; perhaps the designers knew a thing or two about aerodynamics, who could have guessed.
• Under the wing (Bf 109 or Spitfire style) vs leading edge radiators: Ideally under the wing is better (see above), however handling the boundary layer becomes a problem, particularly as the height is quite limited. Leading to the conclusion (from the Drela paper) that "The pros and cons of aft-mounted and front-mounted airfoil/heat-exchanger configurations have been examined with both computational results and some preliminary experimental data. The front-mounted configurations appear to be inherently superior."
• Wing vs. fuselage/nacelle mounted radiators: Ideally you want to have a circular radiator and cylindrical/tubular ducting, in order to minimize the surface area of the ducting vs. the volume (or area of the radiator), in order to reduce skin friction. Wing mounted radiators are at a disadvantage here, because by necessity they are rather short and wide, meaning they have relatively higher ducting surface area compared to a radiator which is more square or circular. There is also a mention of wing mounted radiators affecting the lift properties of the wing, although there's no general rule of thumb here, but something which must be taken into account in the design of the aircraft.

As for the issue of how to mount a Meredith radiator on the nacelle of a multi-engine aircraft, yup that's definitely a problem. You can't really have the inlet in the high pressure region under the wing, as that is usually straight in the path of the exhaust of the engine, which is obviously a bad idea. Also the landing gear gets in the way. http://enginehistory.org/Installations/MeredithRamjet.pdf shows one hypothetical installation in Figure 11 with a chin mounted inlet scoop, and the radiator behind the engine. Perhaps it would be possible to fit both the radiator and the landing gear in the nacelle if one offsets both of them slightly to each side? In particular, using "single strut" landing gear support instead of two struts on either side of the wheel like e.g. the Mosquito had. It is also mentioned that the chin scoop gets a slight pressure increase due to the propeller. Another interesting detail in Figure 11 is that the engine air inlet is in the radiator duct (just before the radiator matrix) benefiting from the pressure rise in the diffuser.

 

[drgondog]

Original radiator on XP-51/Mustang I was changed towards A-36 and Mustang II, and changed again for the Merlin Mustang where the intake gained the prominent distance against the fuselage. So perhaps the early radiators were not as perfect as we often think about them?
I'm also not sure how much the oil radiator on the MC.202 messed the airflow towards the entrance of the coolant radiator.

Tomo - you are correct. The NA 73 improvedby dropping the upper lip from the wing about 1 1/2 inches. Successively the inner vanes in fron of radiators were reduced, the lip was dropped from wing by 1 1/2 inches, and theplenum design was changed to improve pressure distribution across the radiators (NA-83), the variable intake area front scoop was changed to fixed (A-36), the conformal upper lip of A-36 was changed to 'flat' (P-51A)and radiator changed from Round to Rectangular/Horseshoe.

The XP-51B required bigger radiator/Intercooler and went to rectangularbut Intercooler on top and moved oil cooler in front of radiator. Temp issues due to pressure distributions as well as the harmonic boundarylayer compressing in the plenum forced chanes to plenum, rotate the radiator 90degrees, add BL splitter and drop the top lip further. Then introduce angled intake scoop - all before NA-102/104 Production P-51Bs.

 

[drgondog]

A Spitfire with full Meredith-effect capability would have been the ultimate fighter of WW2. It was already the supreme dogfighter. Coupled with a speed increase of 40 or 50 km/h it would habe been superior to all other super-props with maybe the exception of the P-51H. Your opinions?

as long as you define 'ultimate fighter' short of long range air superiority or superior fighter bomber.

 

[MIflyer]

While not Meredith in nature the later P-38's had the radiators moved further out away from the boom structure , even though they were the same size as the earlier ones. They added a lip to the front side of the intake to separate out the boundary layer air and that improved cooling. Of course that same approach was used on the Allison engined Mustangs as well and also became a feature on the P-80A. I don't think you can have a proper Meredith Effect without that li.p

 

[drgondog]

While I agree comment on BL separator, you need a converging plenu and variable opening exit scoop to achieve the jet effect.

Five features were required:
Expanding plenum designed to retain attached BLwhile reducing velocity at radiator face
Nice pressure distribution across radiator face,
Slowed passage through radiator mix to increase heat exchange
Converging plenum to increase velocity of high energy exit air
Converging variable area exit scoop to (attempt) optmize jet effect.

Few designers got the 'rear end' part right, although Martin Baker comes to mind as comparable.