dogsbody Posted February 14, 2020 Share Posted February 14, 2020 Yes there were variations between the Canadian Fairchild-built Bolingbrokes and Bristol-built Blenheims. There were requests from the RCAF for alterations to fit American-made equipment. Perhaps someday, Carl Vincent will publish what he has written about the Fairchild Bolingbroke. It's quite interesting and informative. Chris Link to comment Share on other sites More sharing options...
72modeler Posted February 14, 2020 Share Posted February 14, 2020 (edited) 3 hours ago, Tail-Dragon said: the oil cooler exhaust duct (that squarish duct at 1 o'clock) on the cowl behind the cowl flaps, @dogsbody Chris, Looking at the photos and your comments regarding the oil cooler exhaust ducts on the Bolinbroke/Blenheim, I have a question- just where are the oil cooler matrices located? If I am correct, the flared trumpet intakes at the 9 o'clock position in the cowl ring are for the carburetor and oil cooler; if the oil cooler hot air exhaust duct is the structure pictured at the 2 o'clock position, how is the air ducted to/from the cooler and where is it located? Trying to figure that one out, just to satisfy my curiosity , as it doesn't impact making the model, but I am having trouble figuring out the trunking and position of the oil cooler. See the link to a collection of aircraft photos taken at Goodwood. and scroll down to the Bolinbroke cowling photo. I can see the plated over intakes for the heating system installed on the Bolinbroke, as well as the carburetor and oil cooler intakes- which one is which, and how does the air get to the cooler and across to the other side where the exhaust duct is? Mike https://busy.org/@s0u1/goodwood-revival-review-2 Edited February 14, 2020 by 72modeler added link Link to comment Share on other sites More sharing options...
dogsbody Posted February 14, 2020 Share Posted February 14, 2020 The two trumpets are oil cooler intakes. The carb intake is under the cowling. Chris 2 Link to comment Share on other sites More sharing options...
Tail-Dragon Posted February 15, 2020 Share Posted February 15, 2020 … and if you follow the ducting along from item 1 above, you see the exhaust duct for the exiting air, the item I referred to. Curiously, even the drawing shows notched cowl flaps. 1 Link to comment Share on other sites More sharing options...
72modeler Posted February 15, 2020 Share Posted February 15, 2020 2 hours ago, dogsbody said: The two trumpets are oil cooler intakes. The carb intake is under the cowling. Chris, What an idiot! I clean forgot about the carburetor intake under the cowling, and I even bought the SBS Model tropical intakes when they came out! The diagram you posted makes it all clear- I figured there just had to be some trunking into a centrally mounted oil cooler and then more trunking to the outlet on the other side. I wonder why Bristol used two separate trumpets and ducting to the oil cooler, when a single rectangular intake and single trunk would have been easier? Like the ones on the Martlet/Wildcat. Thanks so much for posting the photo and diagram. Mike Link to comment Share on other sites More sharing options...
SleeperService Posted February 15, 2020 Share Posted February 15, 2020 13 hours ago, dogsbody said: I'm thinking it's the single Vickers gun that was in the early Blenheim turrets. Chris Of course it is! Makes sense as the rear gunner wouldn't prioritise stowing the gun in that situation 11 hours ago, dogsbody said: Yes there were variations between the Canadian Fairchild-built Bolingbrokes and Bristol-built Blenheims. There were requests from the RCAF for alterations to fit American-made equipment. Perhaps someday, Carl Vincent will publish what he has written about the Fairchild Bolingbroke. It's quite interesting and informative. Chris This may be the book Aviaeology has hinted about. I'd really like to see it too. For future reference you lovely people summed it up for me sometime ago. Bolly I is a Blenheim I with the extended Blenheim IV nose. Bolly IV has the redesigned cockpit layout with American instruments as a minor part of the upgrade. 5 hours ago, 72modeler said: Chris, What an idiot! Mike Not at all, progress is made through observation, thought, speculation, decision, and finally seeking confirmation 1 Link to comment Share on other sites More sharing options...
Dave Swindell Posted February 18, 2020 Share Posted February 18, 2020 On 15/02/2020 at 02:30, 72modeler said: I wonder why Bristol used two separate trumpets and ducting to the oil cooler, when a single rectangular intake and single trunk would have been easier? A single trunking would no doubt sound logically easier, but bear in mind that the cowling needs to be kept as small as possible and the trunking therefore has to pass between the cylinder heads. The frontal area available between two heads is fixed, and the simplest form of trunking (a tube) is therefore restricted in diameter by this available space. One tube of the maximum diameter wouldn't provide enough air flow for the required cooling load, and with two fitted this was marginal. The original cooling tubes had a square cut front opening (ie just a straight tube end), later builds had the conical extension on the front to use the ram effect to force more air through the same size tubes. This may have some bearing on why the cowling gills were originally straight but later cut away as illustrated above. With the quest to get more air flow through the cooler, the outlet duct was most likely enlarged as well to form a divergent nozzle to try and assist the air flow. The solution to the problem was to move the coolers into the wing in the Blenheim mkV/Bisley. 2 Link to comment Share on other sites More sharing options...
dogsbody Posted February 18, 2020 Share Posted February 18, 2020 4 minutes ago, Dave Swindell said: A single trunking would no doubt sound logically easier, but bear in mind that the cowling needs to be kept as small as possible and the trunking therefore has to pass between the cylinder heads. The frontal area available between two heads is fixed, and the simplest form of trunking (a tube) is therefore restricted in diameter by this available space. One tube of the maximum diameter wouldn't provide enough air flow for the required cooling load, and with two fitted this was marginal. The original cooling tubes had a square cut front opening (ie just a straight tube end), later builds had the conical extension on the front to use the ram effect to force more air through the same size tubes. This may have some bearing on why the cowling gills were originally straight but later cut away as illustrated above. With the quest to get more air flow through the cooler, the outlet duct was most likely enlarged as well to form a divergent nozzle to try and assist the air flow. The solution to the problem was to move the coolers into the wing in the Blenheim mkV/Bisley. All Mercury and most Pegasus engines had the two-trumpet intakes at the forward edge of the cowl opening. Some at the bottom, as on the Gladiator and some at the top. You just have to look closely. Chris 2 Link to comment Share on other sites More sharing options...
dogsbody Posted February 18, 2020 Share Posted February 18, 2020 Some photographic evidence: Chris 2 Link to comment Share on other sites More sharing options...
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