Been wondering about this

[wuzak]

What advantage/disadvantages does an annular radiator have over the following

• Chin mount (Lancaster/P-40)
  
• Belly Mount (P-51)
  
• Wing-root mounted (Mosquito)
  
• Side-mounted
  

Depends how it is done and who you talk to.

Napier claimed less drag from their annular radiator than for leading edge (2nd best) or chin radiators. But the Tempest VI with anular radiator was no faster than the Tempest I with leading edge radiators and less power.

Annular radiators would work on something like the B-17/B-38 conversion because the firewall is already much larger in diameter than the engine. A little less useful on something like the P-51, as it had a narrow fuselage. The Tempest, on the other hand, was designed to take the Centaurus.

[wuzak]

So, if the Merlin were used, what would have been the most likely installation, beyond simply bolting it on?

Would the nacelle be modified to allow for a Mustang-type scoop, which would allow the "Meredith Effect" to take place?  Because if memory serves me well enough, the supercharger on the Merlin was integral with the engine itself, along with the same ducting and gills that the Halifax and Lancaster had. I could be mistaken about that, though.

Depends which Merlin you use.

If you are using a single stage engine, something like the Merlin XX power egg, as used on the Lancaster or Beaufighter, could be used.

If you use a two stage engine, you need more radiator and an intercooler radiator (liquid cooled). The B-17 already has an intercooler radiator, though that was an air-air unit. You could replace that with the liquid cooled intercooler and use the existing ducting - though that may not give enough air.

I think you woud struggle to have a Mustang style scoop. You would want to put it on the power egg to avoid too much modification to the main structure. Plus, the inner nacelles have the wheels.

[wuzak]

Because if memory serves me well enough, the supercharger on the Merlin was integral with the engine itself, along with the same ducting and gills that the Halifax and Lancaster had.

The R-1820 and V-1710 both had a supercharger integral with the engine, as did the Merlin.

In the case of the B-17, XB-38 and P-38 a second stage supercharger was added, in the form of a turbo.

The Merlin wasn't used with a turbo, instead using a two stage supercharger which was integral with the engine.

The V-1710 supercharger can be seen at the right in this image.
http://www.aviation-history.com/engines/allison_cutawaya.jpg

The Merlin 61's supercharger
http://www.aviation-history.com/engines/merlin-supercharger.jpg

[wuzak]

I wondered if a B-17 would work with two powerful engines, rather than 4 less powerful engines.

Perhaps a Sabre, V-3420, R-2800 or R-3350. Or even a Vulture!

With the proximity of the fuselage to the inner engines, contra props would probably be needed.

Sabre with annular radiator
http://s91.photobucket.com/user/Major_Sharpe/media/1946-1442-1.jpg.html

http://i91.photobucket.com/albums/k304/Major_Sharpe/Hawker-Tempest-1-px800-1.jpg

Curtiss P-60 with contra-prop R-2800
http://www.nationalmuseum.af.mil/shared/media/photodb/web/061024-F-1234P-014.jpg

Hawker Tornado with Contra Props
http://i262.photobucket.com/albums/ii120/Duggy009/Hawker-Tornado-R7936-contra-rotating.jpg

[maxmwill]

Well, the test bed B17, the Boeing 200Z, was used to test several engines, a couple turboprop engines and a 3350, mounted in the nose

http://www.in2guitar.com/b-17/test.jpg

Here is a turboprop in the nose:

http://www.n6cc.com/wp-content/uploads/B17Five.jpg

[maxmwill]

If you're interested in building a model of the XB38, I found this, which might help a bit:

http://modelingmadness.com/review/allies/us/beatoxb38.htm

[zenrat]

See how good a B17 looks with 5 engines?
I built one 30 years ago but its long gone.

[wuzak]

Happened across this earlier What If thread when looking for B-17 pics.

http://www.whatifmodelers.com/index.php?topic=15775.0

Thta has pictures of a B-17 fitted with 4 x Rolls-Royce Dart turbo-prop, and a work-in-progress Merlin B-17.

[PR19_Kit]

Happened across this earlier What If thread when looking for B-17 pics.

http://www.whatifmodelers.com/index.php?topic=15775.0

Thta has pictures of a B-17 fitted with 4 x Rolls-Royce Dart turbo-prop, and a work-in-progress Merlin B-17.

Dart powered B-17 looks great! Next pic, are those U.S. V-1's under the wings?

They certainly look like them, I think they were called 'Loons' in the US.