Why an INVERTED V-12? PART 2

greetings this is Greg I decided to make a quick follow-up the video regarding the reasoning for using an inverted V type engine in an aircraft I have another video on this subject if you don't watch that one first this one may not make a lot of sense link is in the description there have been so many comments on my previous video that I decided the best way to address them was with the follow-up so here goes let's start off with the fuel injection and carburetors quite a few people have suggested that the decision to use either fuel injection or carbs may have had an influence on the need to go with either an upright or inverted engine and I understand why someone might think that if you take a look at a typically configured automobile v8 engine as shown here you can see it set up with the carburetor at the top in a downdraft configuration you certainly can't flip this over and run it inverted however it's important to understand that down draft carbs are not the only type there are updrafts side drafts and more so inverted engines could be and often were run with carbs it's just not a limitation in fact they could even be run with downdraft carbs mounted at the back of the motor and manifold into the cylinders in fact that's usually how it was done take a look at the carb location on this Allison and you can see that it really wouldn't matter in terms of carburation if the engine was flipped upside down the carb could stay the same orientation relative to the airframe meaning right side up in the downdraft configuration and the air fuel mixture would still be pushed by the supercharger to its destination the Ranger six-cylinder was inverted and it used an upright carb although I can't find a picture of the carb itself in the case of the 109 some early prototypes were fitted with carbureted lumo two tens and later carbureted DB six hundreds both of these were inverted v12 so I just don't think there's any question that both carbs and fuel injection were both useable on inverted and upright engines thus I don't think the decision to use carbs or fuel injection has any significant impact on which engine configuration to use next we need to talk about machine guns that are mounted on or fire through the cowling call them cowl mounted centerline mounted or whatever this has come up a lot so let's take a look I understand why someone might think this is related to the inverted design in the case of the one I'm the cowl mounted guns an inverted engine are distinctive features of the airplane and generally speaking Allied fighters on the Western Front used wing mounted guns so the 109 set up when looked at from say about a 1942 or later US or British point of view might seem pretty unique however work on the 109 began in 1934 before that and after Cowell mounted guns were not only common they were the norm and with all possible engine types starting with Roland Garros his plane in World War one and for the rest of that war cowl mounted machine guns were standard it didn't matter if the plane had an upright v-8 a rotary or an inline six-cylinder things didn't change much in the 1920s generally speaking fighters had guns that fired through the cowling usually but not always mounted up high in the 1920s we started to see wing mounted guns show up the cowl mounted was still the norm this continued into the 1930s cowl mounted guns remained the norm and were sometimes supplemented by wing mounted guns in the US the p35 had cowell mounted guns so did the p36 and many others sometimes as with the Gloster gladiator shown here a british airplane they mounted them lower but still firing through the cowling and near the centerline of the plane in the case of this Japanese fighter they have the guns mounted so low in the cowling they fire between the engine cylinders at about the 1 and 11 o'clock positions the early USP 40s had 2 50 calibers mounted in the cowl over its upright v12 supplemented by 30 caliber wing guns at this point the p40 has larger guns over its upright v12 than the 109 has over its inverted engine newer versions of the p40 switched to an all wind mounted 50 caliber setup which was rapidly becoming the standard US configuration and that's a story for another time interestingly the Soviets with their p-40s seem to go to the other direction sometimes removing the wing mounted guns and keeping the cow mounted guns speaking of the Soviets they favored cowell guns and they didn't use an inverted v12 the lavochkin la-5 and I don't know if I'm saying that right the Russians always correct me anyway it mounted to 20 millimeter cannons above its radial engine so from 1915 all the way to about 1940 and beyond cowl mounted machine guns were extremely common on fighters with every possible type of engine upright inline six cylinders and B 12 radials rotaries and of course inverted v12 I just don't see any way that the decision to use an inverted engine was due to the desire to mount machine guns in the upper fuselage or on the calendar history shows us otherwise now you can make the argument that with the inverted engine the guns could be mounted a bit lower but that's an argument for visibility which I do think was a factor everything is a bit lower with the inverted engine which I think was largely the point so what about the cannon firing through the propeller hub again it's just not limited to use with an inverted type in fact it doesn't really matter the space in the middle of the V for the cannons barrel is present regardless of engine orientation other airplanes with upright v12s have cannons that fire through the propeller hub these include the French d520 and the yak-9 in the case of the 109 I have the impression that a lot of people think the cannon was mounted in the middle of the V and that the machine guns were over the engine that's not quite true only the barrels are in those locations the main portions of the gun are there aft this picture of the 109 with guns installed and no engine should do a good job of explaining this as for ammunition it's stored well after the engine and thus ammunition quantity is not affected by the decision to go with an inverted or an upright engine now quite a few people have pointed out the effect of an inverted engine on propeller right this is a big factor in lower powered training and liaison type aircraft that's because in these planes the propeller is directly driven by the crank and thus it's in line with the crankshaft as an example take a look at this Fokker d7 and note the location of the propeller when using its direct drive up right inline 6-cylinder now take a look at a replica used in the movie the Blue Max which by the way is a fantastic movie notice it's using an inverted engine and thus the prop is higher because again it's also being driven not directly in line with the crankshaft for this reason inverted engines were common on lower powered airplanes to increase prop clearance but why not on fighters here's the reason higher powered planes need larger propellers and you eventually run into an issue with propeller tip speeds so you need a gear reduction to slow it down for example some Merlin's use a point for two-to-one reduction so that at 3,000 engine rpm the prop would only be turning 1260 rpm with the Ranger six-cylinder we showed earlier if it's turning 2400 rpm which it did do it's relatively small prop would also be turning 2400 rpm the gear reduction mechanism and I circled it here are the DB 601 moves the prop back down so no increase in prop clearance is going to happen the actual position of the prop isn't really affected by the choice to use an inverted engine because in the case of an upright engine the prop is moved up as a result of the gear reduction and in inverted engine it is typically moved down and both end up in about the same place radials also used gear reduction but they're in line with the crank which generally wasn't done with v12s there is a reason for that having to do with optimal placement of the throat centerline so I hope that clears up the most common questions that I see in the comments section on the other video I just don't think the decisions were based on armament and the initial capacity or in the case of world war ii fighters prop clearance I am still leaning towards visibility and maintenance the more I think about it the more I think maintenance was a big factor imagine you're working on the Eastern Front sometime in 1941 while it's raining or snowing imagine you have to change the spark plugs on a p40 you're gonna need a ladder and you'll need to keep getting on and off that ladder to move it as you work your way around all 12 cylinders then every time you drop a tool or worse you drop a nut or a bolt and you car guys know what I'm talking about here it's gonna get stuck somewhere in the engine and fishing it out will take time oh and you're probably doing this at night the 109 mechanic can do all of this with his feet on the ground and if he dropped something it's far more likely to hit the ground rather than get stuck in the bowels of the engine plus he doesn't need to go up and down a ladder every time he needs another tool drop something there just needs to move to another part of the engine I think that from this perspective the inverted design is a big help in actual frontline operations that's all I have for now I'm gonna get back to work I'm finishing my p-47 series as well as my new 190 series and some other topics I have coming up p-51 and 109 aerodynamics as well as another muscle car automotive video anyhow thanks for watching and goodbye for now have a good day

Channel: Greg's Airplanes and Automobiles

Views: 138,586

Keywords: Messerschmitt Bf109, Bf109, ME109, WW2 fighter, Inverted V-12, Inverted V12, DB601

Id: e7R39tJ7psw

Length: 10min 46sec (646 seconds)

Published: Sat Apr 13 2019