Whirly Posted October 20, 2018 Share Posted October 20, 2018 Hello, I did some research on the various versions of the Kingcobra preparing for the build of a model in 1/72 and noticed one detail which is never mentioned in the version details, nor taken into accounts by the kit manufacturer. If you look at an early mark, such as this P-63A from Monino, you'll see two intakes per side: the smaller one is really tiny and often invisible when looking from the side or covered by the shadow of the fuselage in most of the full picture images you can find online. This is the configuration that every plastic kit I could look at usually reproduce, even the very recent Dora Wings kits. If you consider a later mark though, for example this P-63E from the USAF Museum... ...or this P-63E from the Pima Museum... ...or again this Commemorative AF P-63F, you will notice that there is only one slightly wider intake per side. If my observations are correct you need to correct this detail in any kit to make a late mark , and this seem on the whole quite feasible, though I'm interested to know the reason for this change which is not usually documented. Any Kingcobra expert willing to contribute? 2 1 Link to comment Share on other sites More sharing options...
72modeler Posted October 21, 2018 Share Posted October 21, 2018 I'm not an expert, and I couldn't any definite statement in any of my P-63 references as to why the wing root inlets on the P-63A and subsequent versions were different, but I think the small separate inlet on either side of the P-63A wing root was for the oil cooler, with the larger opening being for the coolant radiators; with the P-63C and later versions, it appears the small inlet dedicated for the oil cooler was incorporated into a single larger opening that fed both the oil cooler and the coolant radiators- looks like this increased airflow to the oil cooler. I do remember reading in one reference that the P-39 dedicated more air to the oil cooler than to the radiators, which caused chronic overheating, and the proportion of air to the oil cooler and radiators was reversed in the P-63, which eliminated the overheating problem. Perhaps this small inlet to the oil cooler in the A-model then caused higher oil temperatures, so the inlets were revised for the subsequent Kingcobra variants. Only an uneducated and unproven theory on my part, to be sure, but hopefully somebody with more knowledge on the subject can give you a definitive answer to your question- BTW, I never really noticed the difference in the two inlet configurations before you brought up the subject and posted the photos! Great- yet another modeling !! Mike 2 Link to comment Share on other sites More sharing options...
JWM Posted October 21, 2018 Share Posted October 21, 2018 The hypothesis of Mike seems OK to me. If you look into the inlets of other then Monino machine you can easily see the split for two parts, smaller inner and bigger outer. So only the shape of leading edge opening changed. Deeper you have still two streams of air going to two different coolers... And the aerodynamic properties of the small inlet in P63 A was not perfect as it was too close to fueselage, so likely in turbulent flow zone. Moving it a bit outsise (and a bit larger) certainly improved the cooling efficiency. Regards J-W Link to comment Share on other sites More sharing options...
72modeler Posted October 21, 2018 Share Posted October 21, 2018 8 hours ago, JWM said: The hypothesis of Mike seems OK to me. If you look into the inlets of other then Monino machine you can easily see the split for two parts, smaller inner and bigger outer. So only the shape of leading edge opening changed. Deeper you have still two streams of air going to two different coolers... And the aerodynamic properties of the small inlet in P63 A was not perfect as it was too close to fueselage, so likely in turbulent flow zone. Moving it a bit outsise (and a bit larger) certainly improved the cooling efficiency. Regards J-W JW- I was thinking after I posted that maybe it had something to do with the boundary airflow at the wing root- with that inner intake right up against the fuselage, it probably wasn't very effective...I know most intakes/splitter plates on weenie cookers are away from the fuselage to get them out of stagnant air, but wasn't sure how to describe this. (We're either both very smart, or both wrong on this) I hate it when a really interesting topic/observation/question gets posted that I have never noticed before and then I can't find anything out there that covers/explains it despite searching through all of my references and the internet! We modelers are a crazy bunch! Cheers! Mike 1 Link to comment Share on other sites More sharing options...
JWM Posted October 21, 2018 Share Posted October 21, 2018 Mike, besides a modeller I am a physicist... So I am thinking we are both right in understanding motivation of tha change Cheers J-W 1 Link to comment Share on other sites More sharing options...
Graham Boak Posted October 21, 2018 Share Posted October 21, 2018 They are called boundary layer diverters. Or just splitter plates, depending on type. 1 Link to comment Share on other sites More sharing options...
Magpie22 Posted October 22, 2018 Share Posted October 22, 2018 The Bell Model 33, (P-63A and P-63C), center section had the oil cooler mounted on the centerline and the engine coolant radiators outboard of that. All were fed from the 'letterbox' intakes in the leading edge. If you look closely at the top pic you can just make out the splitter which diverted air inboard for the oil cooler, the remainder going through to the engine coolant radiators. The small triangular intakes provided air to the cabin. Whirly, you are correct that the later models had a different intake configuration. The Bell Models 41 and 43, (P-63E and P-63F), had a redesigned center section. The V-1710-109 and -130 engines in these models had greater oil and engine coolant requirements. The span of the center section was increased by some 10 inches and the intake leading edges and ducting were redesigned for increased pressure recovery at the radiators. P-63 induction and cooling and its associated intakes and ducting are indeed a You have to get into the various engine models, superchargers, and induction layouts to try and make some sense of it all. Peter 3 4 Link to comment Share on other sites More sharing options...
Whirly Posted October 24, 2018 Author Share Posted October 24, 2018 Thank you all for the useful contributions! I suspected there was some basic change in the cooling system involved, though I expected this redesign to happen with the C model when the engine got the first power increase. The only hint given with the E model is a generic wingspan enlargement in all the references I read through, would you be so kind to tell us which books mention the cooling system redesign? Link to comment Share on other sites More sharing options...
72modeler Posted October 25, 2018 Share Posted October 25, 2018 18 hours ago, Whirly said: Thank you all for the useful contributions! I suspected there was some basic change in the cooling system involved, though I expected this redesign to happen with the C model when the engine got the first power increase. The only hint given with the E model is a generic wingspan enlargement in all the references I read through, would you be so kind to tell us which books mention the cooling system redesign? The information for my posts were taken from several websites on the P-39/P-63, as well as Cobra! by Birch Matthews and the AJ Press monograph on the P-63. Magpie 22 seemed to have the best information regarding the description/changes in the P-63 intakes/oil and coolant radiators. so perhaps he can tell you where he got his information. Mike I'm still trying to find definitve information on whether or not any variants besides the one-off P-63D and the P-63E's had the larger 39' 2" wingspan. I think the RP-63's- both A, C, and G variants all had the standard 38' 4" wingspan. (The RP-63G preserved here at Lackland AB, serial 45-57295, certainly has the 38' 4" span, as I have crawled all over that puppy with a tape measure and camera!) Link to comment Share on other sites More sharing options...
72modeler Posted November 5, 2018 Share Posted November 5, 2018 I found this video of ex-astronaut Frank Borman's beautifully restored P-63A, and it shows among other things the oil/coolant radiator intakes that we were discussing. A very nice restoration, as it has dummy ammunition, ammo cans, and weapons for the nose-mounted machine guns and cannon, as well as the correct external tanks, pylons, and brackets. With the Dora Wings Kingcobras out now in both 1/72 and 1/48 scales, I thought this might be useful to some of you. If you do a search for Frank Borman's P-63A, you can see other photo collections and videos of his airplane. Mike https://www.youtube.com/watch?v=1tImCbFjec0 1 Link to comment Share on other sites More sharing options...
TISO Posted November 8, 2018 Share Posted November 8, 2018 Just for clarification if you are talking about small triangular intake old 1/72 TOKO/Eastern Ekspress kit has it 1 Link to comment Share on other sites More sharing options...
roginoz Posted November 9, 2018 Share Posted November 9, 2018 So does the 1/48 Hi-Tech kit. Link to comment Share on other sites More sharing options...
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