V6 engines are a big issue to balance. 60° works fairly well but do have a rocking couple. Depending on whether even fire or odd fire, the balance is affected. They have either a forward/back rocking couple or they duck walk. The odd fire ignition is an issue. The Ferrari Dino was a 120° vibrating wonder, acceptable in a race car but not so good in a street car. A 90° V6 has the advantage of being able to be machined using the same tooling as V8 blocks. The early Buick V6 was odd fire using common crank pins like a V8. Eventually they changed to even fire with split rod journals. When Chev was developing their 90° V6, they built test engines with various rod journal splits including even fire, and installed in cars for staff to drive for a week or two and then switch to another. They asked the staff which they found most pleasant to drive. If I remember correctly the 18° split was the most pleasing, so the early 3.2l and 3.8l Chev engines were "semi oddfire". The 4.3 went to even fire. With V6 engines the shakes are tuned out using mounting rubber durometer so the passengers do not feel it.
I’m a mechanical engineer who’s been into engines since I was a kid. This is the only explanation of secondary imbalances that I actually understood. Most videos glaze over the specifics. Great video. Thanks for the time and effort you put into this. Good luck growing your channel.
That was awesome your a wealth of information technical data second to none I can hear a true enthusiast and avid fan of those amazing war time engines
From my understanding 90 degrees is optimal for engines with fewer cylinders because primary balance is more important than even firing order. In some applications like motorcycles, uneven firing order can be an advantage because it allows the rider more control at the limit of tire grip.
Great video. Turbos DO have parasitic loss on the engine in the form of back pressure on the cylinder. Doing work with the exhaust means resistance on the exhaust. Early turbo chargers were not as efficient as modern turbos so that was a lot of loss for less gain. This is more apparent on low compression engines than on high compression engines as the pressure differential between cylinder and atmosphere is greater. This is why turbo diesels are not just power adders but also efficiency adders even though there is the parasitic back pressure. Using that spent heat to add power is getting that power back. However, if we use the spitfire as an example, they already USED the exhaust energy as thrust, so putting a turbo on that would be robbing one of the ways they were already scavenging that wasted power.
I tend to think of it as mechanical parasitic loss, so I should have worded it like that. Yes a turbo restricts exhaust flow so would result in a loss, although typically nothing close to the loss of a supercharger. Thanks for the comment!
@@LetsGoAviate understood. Just have to beat back the tide of "turbos are FREEEEEEEE". They are almost free, especially for diesels. Modern diesels cannot work without them because they have been designed with turbos in mind. There is valve overlap which can only be there BECAUSE of the back pressure. If you want to learn more, just out Gale Banks. He's an unmitigated badass
A turbo raises the overall pressure. The boost and back pressure are approximately equal. The classic analogy is a normally aspirated engine in a deep mine shaft where the air is denser. The exhaust ‘blow down’ pressure is about equal to the peak compression pressure. Say 125 psi and 1200F. That is one heck of a lot of energy. Turbo-compounding captures this…Wright 3350 PRT….increases hp by 15-20%. Modern turbo-compounding has made its way into truck diesels. A turbo is more efficient than a supercharger even if the latter’s exhaust propels the plane. (Jet propulsion efficiency suffers if a great mismatch between the plane velocity and exhaust velocity. ) With turbos the pilot does not have to change supercharger settings with altitude ….a consideration in combat. Cheers
@@danbenson7587 that's not entirely correct. A turbo increases air density. If the heat put into the air is removed, then the pressure is also reduced, hence the value of forced air cooling. This may seem pedantic but all good charge systems have cooling. Regardless, it is the differential between the exhaust and atmosphere which matters for energy input and it is increase air mass in the cylinder which matters for combusition. No one thinks on PSI in and PSI out
@@coreyfro The loss of pressure with cooling applies to a closed volume. This isn’t the case here. The hot air exiting the turbo pressures the air ahead of it that is passing through the charge intercooler. There is a bit of aerodynamic pressure loss thru the cooler though. The intercooler increases charge density. On SI engines for power and knock; on CI engines for power. Ci engines are available w/o intercoolers. BTW, interstage charge coolers have been used on gas turbines for same reasons. Miss your drift on PSI comments. ….Though I haven’t a charge cooler, I am dense. Cheers
Outstanding!! A technical deposition of this depth is long overdue. One subject of fascination to me has always been the 45 degree included angle of the WWI Liberty V12. Might be an interesting subject at some time. Keep up this great, great work!
45° to keep the engine as narrow as possible. Same displacement as the Merlin by the way. Also built as an inverted air-cooled V-12 with the displacement reduced.
Amazing vid, very clear explanations and complex subjects made simple enough to understand. Very well done indeed. Something that I’ve struggled to understand is dry sumps, especially in inverted V12 engines - when flying level, why doesn’t the oil collect in the cylinder above the piston is a thought that has often occurred to me and I’ve never found a satisfactory answer. If you could find a way to explain this in a future vid I’d really appreciate it. Love your delivery and pace, I found the material easy to follow, as someone who used to do technical training for a living I find your technique and presentation refreshingly good. I will add my bravo to those already here.
Thank you for the nice comment. I think the short answer is when running the pistons move way too fast for oil to pool in the cylinder. With the engine off it's another story. I'll work it in when doing a video about an inverted engine.
Awesome video! Love that you showed the clip of the lightening, it had an extra advantage, the guns shot straight on, no convergence.. ask yamamoto when he got killed in his betty, the one survivor explained how precise then gunfire was, killed the gunners before they could even man their stations, and It was fast, really fast for the time. Oh when you get to hell, i mean, you can ask him, the desighner of the pearl harbor attack.
When I read the video title, I clicked because OBVIOUSLY, you'll discuss why WW2 German V12s were inverted, and all the pros & cons that came with it. That's a HUGE technical difference but not even a single mention.
😆 I had to keep the video short(ish), I couldn't possibly cover every single thing I wanted to, and tried to keep to the tech. For every viewer something else is more important, so to many I will have left out something important to THEM. There isn't much to it, engines are almost always mounted upside down to improve forward visibility. But you also get a lower centre of gravity, and maintenance is easier, especially in more remote locations. The cons are that it needs a dry sump oil system and potential problems with hydrolock with oil seeping into the cylinders, though as far as I'm aware the DB 600 series didn't really struggle with this.
@@LetsGoAviateweren't all aviation v12 dry sump? It would be inconvenient for your fighter engine to explode as soon as you pull negative G. Why didn't other countries switch to inverted V?
@@tedarcher9120 You are correct regarding dry sumps. Inverted isn't really "better". Other than the reasons I already mentioned, also being able to mount a cannon to shoot through the nose. So better visibility over the nose, lower C of G and the cannon may have influenced the decision to mount inverted (remember the DB 600 prototype was upright, they turned it upside down later) In hindsight we know those advantages made little, if any, difference compared to the American and British upright V12's.
@@LetsGoAviate with the inverted V12, the thrust line was lower (less prop ground clearance) yet Messerschmitt continued using a 3 bladed prop even when HP increased. I find that the most strange aspect of the Me109s.
My favourite example of why turbochargers where not very popular at the time is the internal diagram of the P-47. Plumbing for the turbo and intercooler took up a lot of space, requiring a fat fuselage to house it all. No doubt it added quite a bit of weight as well. However that plane was also a great example as to why this sacrifice could be worth it even on fighters. Especially late war models on high octane fuel could achieve ridiculous high altitude performance. Even more so if the crew tampered with the turbine overspeed protection to maintain max boost to even higher altitudes. It's just that at low to medium altitudes the compactness and simplicity of pure supercharging far outweighed the mechanical efficiency of turbocharging. At least through most of the war when manifold pressures remained somewhat modest.
Great video! The issue with the Jet Fuel powered compression ignition engines is that cetane index isn’t in the Jet Fuel specification. Hence operability may vary significantly!
Not all aviation V-12s have been 60° bank angle. The Liberty was a 45° bank angle. The Libert was also designed as a family of engines. A four, an inline six, a V-8 and the V-12.
An v12 is two inline 6. An inkine 6 is two inline 3. Inline 3 and 6 both have the 120 deg crankshaft and same secondary ballance. The inline 3 has the rocking issue that can be cancled by an flywheel with same but opposite in-ballance, or by an mirro 3 inline to create the 6 inline. So an inline 3 is simple to ballance and heavy used in modern cars. Main advantage by the inline 6 is the self ballance and the 120 deg fire order. An v8 can also be in ballance but will then have an uneven fire order. Today 2 cylinder boxer in smaler airplanes taken from BMW motorbikes are popular due to ballance and small dimension.
the centrifugal superchargers used by the ww2 engines usually didnt increase the boost linearly as the rpm increased... the boost of the centrifugal supercharger increases pretty much exponentially with the rpm which is one of the major annoyances in supercharger design.
Yeah it really only starts moving sufficient air at higher rpm, much like a turbo. But it's a non-issue in aviation, as opposed to an annoyance on cars.
@@LetsGoAviate arguable. while ww2 aero-engines have a narrower rpm band than car engines and its less of a problem, they still have an rpm band and therefore this is a factor. and especially when starting the engine it changes things a lot as the low compression ratio has a hard time creating enough pressure to allow for good ignition. and stuff like that.
Not really an annoyance at all in aircraft engines. Accelerating from idle they are only accelerating themselves and the propeller so low boost isn’t a problem-just like aircraft ignition timing is fixed for the same reason. And the engine spends most of its time at a constant RPM.. either max in combat or a significant percentage of it so boost is always high. The boost levels are controlled by the throttle. Lots of aircraft engines with single speed superchargers are “ground boosted” which means that they produce way too much boost on the ground.. the idea being is that you can use the throttle to get maximum boost for several thousand feet rather than having it fall off immediately as the aircraft climbs.
the problem with exhaust stacks as seen in ww2 aircraft is that, while they produce thrust, they're not producing thrust all the time. a single exhaust on a p-51 of any production type for example will produce a given amount of thrust relative to rpm for 1/4 of the running time, the other 3/4 of the time it's just producing drag. the british tried addressing this by producing 2 into 1 collectors but that only reduces the amount of time it's producing drag to about half. which was still not a net gain. additionally, iirc, when the british did their tests on exhausts proving a 10 mph improvement with the use of angled stacks it was vs. the flush stacks that just blew the air out 90 degrees to the direction of flight. naca did test on this too and all parties came out with some very interesting info but what was really found to work, shrouded stacks and collectors, was seen as too complicated and expensive to produce and maintain as well as not fitting current designs already in production.
To be honest there are many things left out due to time. The video is 33 minutes long already, which apparently is too long for most viewers. Before calling it successful I would have had to go into the high altidude problems with the turbo on the P-38, or someone would have commented how they are surprised I didn't mention it...
Great video. I smiled when you showed a P38 just after saying that turbos were to large tor WW2 fighters - that one had two turbos in the booms. You can see the bulges where the air intakes were located just behind the wings. The Germans liked their V12s with the crankshafts at the top and the heads at the bottom. That probably required a complicated starting procedure. Pragtige aksent! Groete uit Chile.
Thanks. I did specify only the P-39 and P-40 though, not all fighters 🙂 The fact that it required a twin-boom fuselage to host the turbo's drives the point home. Of course the GE turbo did make it onto a single engine fighter, the P-47. A radial yes, but it's a massive plane in comparison and the only single engine fighter to use the GE turbo. There are some excellent photos on the net showing the full GE turbo with all it's systems as in use on the P-47. I couldn't use it in the video as it's copyrighted. It really is massive. lynceans.org/tag/p47/
@@LetsGoAviate Thanks. I'm not a pilot and I'm new to your channel. I liked the Kgaligadi video as I often visited Soda Ash in the 1990s. I remember well once the pan had about one and a half meters of water in it. Quite spectacular waves. One of my sons in law is busy building an aircraft in East London. If interested, how can he contact you?
@@Brommear No problem. My email is listed in the about page of the channel, letsgoaviate at protonmail dot com. Alternatively on Instagram, account is lets_go_aviate
This is why I am a fan of the inline 6 in automotive applications...especially in trucks. I wish the inline 6 was more widely used today in light truck applications, instead of V6's...in some applications, I prefer an inline 6 to a V8....
Many thanks for the however catchable explanation of the balance, which is great :D I assume Klimovs were made out of an Hispano-Suiza V12 licence from the 30s, but why don't you talk about Hispano-Suiza's? Even the Hisso V8 of WWI is interesting for the introduction. Spads (used by the US Army) were faster than Fokkers... Sorry I've seen your video about V8s just now - Very good! Many thanks for it also.
Hi, A most excellent video. I have 2 questions. 1, Why did the germans go with an 80 degree V?????? 2, Where would I go to find/ develop info on the benefit? of building the best ANGLE V2 style engine- aka a 60/75/90 degree block. Which would be best , and WHY? thanks
The RED A03? A wild guess would be to create needed space between the cylinders, which would be much less with a 60° cylinder offset. Being a diesel could also contribute. There's not many reasons to stray from 60° on a V12. With split crankpins a smooth firing interval should still be possible, but the crankshaft becomes more complex. But I did not research this to give a confident answer. Which V2 angle would be best? There are 3 main factors; balance, firing interval and size. Without a balance shaft, 90° is the only balanced option, as explained in the video. The single cylinder on each side of the V is unbalanced and can only be balanced with a shaft or a 90° angle using the crank counter balances. But 90° makes them take a lot of space, and 90° does not result in a smooth firing interval. No v-twin can have an even firing interval, but a narrower angle V will be closer to even and thus smoother. Hope that helps.
Are you by any chance realted to someone named "Oddbawz" who plays war thunder here...? You sound very alike. Interesting Vid, though. I had the pleasure to look into an earlier Allison v1710 years ago, they are insanely beautiful, they polished the valve levers! Not later during the war, but in the 30s. Looks awesome.
At the time of WW2 turbocharger technology was still being developed. Metallurgy was no where near what we have today. Aircraft engine design is vastly different than automotive, more closely resembles heavy duty diesels. Because both run for hours at high duty cycles, read power levels, compared to automotive engines, the webs between the main journals and rod journals must be wider. Also the fillet radius between the web and journal must be a larger radius. These two features help absorb and mitigate stress risers and cracks which will develop into broken crankshafts. The crankshaft throws unwind on the compression stroke and then wind up during the power stroke. Metals when bent repeatedly eventually crack and break. For similar reasons the connecting rods need to be designed for the higher duty cycle loading. Exhaust valves in an engine running at 75% power for hours tend to run hot. Aircraft engine mixture can be adjusted for maximum exhaust temperature which is maximum power for 5 minutes on takeoff. Then most are adjusted to richen the mixture (ROP) until the exhaust temperature drops about 50°F. The extra fuel cools the exhaust valves. The mixture can also be leaned to reduce the temperature about the same (LOP), with the extra air cooling the valves. Running at high power for hours and maximum exhaust temperature will lead to exhaust valve heads breaking off. OOPS. With all this, keeping weight as low as possible while keeping reliability is a delicate balance.
The exhaust gas providing thrust is questionable. It may be static thrust, but at speed the exhaust also creates drag. The drag also creates a venturi effect which lowers exhaust back pressure and improves scavenging. Where did you read about the thrust from the exhaust?
You can find references to it all over the internet. Just Google "Spitfire exhaust thrust". As for the tests I referred to in the video, you can read about it in a wartime report of 1942 called "Flight Tests of NACA Jet-Propulsion Exhaust Stacks on the Supermarine Spitfire Airplane" by Richard L. Turner & Maurice D. White
@LetsGoAviate Looked at the report. The thrust is calculated not measured. The speed is measured but the power is not. They measure air density at manifold but not flow. The additional speed may be because of the thrust, but may be also due to scavenging, the same way a carburettor works creating more power. The engine would produce thrust from exhaust, shame their is no static test without a proper on a dyno. The exhaust that was tested is also not the exhaust that was commonly used in the war.
so knowing this I would build a 12 cylinder boxer engine hidden in the center wing direct cooling ducts in the wing root with a driveshaft to the propeller. think p-39 but a boxer 12 in the center of the wing. wish I could draw the plane I'm seeing in my minds eye is amazing. 6 synchronized 50 cals in the nose 4 20mm in the wings.
I can think of one aviation V-12 that was designed with automotive style side by side rods. Ford's V-1650. While it never saw production as an aviation engine after chopping four cylinders off it was produced as the Ford GAA. The engine was also designed to make use of cast steel parts instead of forging where ever possible to reduce costs. The V-1650 was also designed with an integral turbocharger. And yes the displacement was the same as the Merlin. And the Liberty.
I only recently found out in 1940 Rolls Royce were working on a two stroke 12 cylinder V12 unsure of CC but was Much lighter than the Merlin and Griffin with a power turbo added it was stated from tick over 2200 HP to max of 5200 HP later some tests 5600HP but it was only testing sadly never used. same type of water cooling flatter head Turbo went over the top of the engine from exhaust fully oil cooled. I wonder if you could find out More?
Except that it’s more than just the engine. Take the Allison 1710. It was one of the best allied engines of the war. It was larger than the Merlin, easier to produce, modular, and was designed to use a turbocharger which could deliver maximum boost at any altitude. The P-39 was designed with it.. and it had very advanced features like tricycle landing gear and heavy forward armaments. But the decision was made to delete the turbocharger as it was felt it was too heavy and bulky-even though the mid mounted engine eliminated the need for excessive ducting like the P-47 had. Since Allison hadn’t bothered to make a two-speed supercharger.. it was shipped with a single speed one.. meaning that it lacked high altitude performance.
25:27 absoute nonsense - Turbocharger does have a parasitic loss... there is no free power! Simple example: put a turbo on an N/A engine exhaust, but the charge pipe goes to another engine... the first engine will get bogged powering the turbo .. the pistons have to "fight" the exhaust back pressure trying to push the exhaust out several times per second! Also earlier you used a boxer engine example - I think a flat engine should have been mentioned as well (looks the same externaly as a boxer but each pair of opposing pistons actually share a crank pin). Otherwise, fantastic job!
There are tent towns in all of the major cities and towns. Most of these people have full time work. It's the sort of thing I thought would only happen in places like the US. It's that bad.
Jay Leno has a video where he powers a display model up… makes virtually Every car engine fade to lawnmower engine status including that stupid overpriced Bugatti thing
You cannot understand why the secondary imbalance of a straight 6 engine is cancelled out without starting with a careful look at the slider crank equation. Start with the derivation of the equation. See that the secondary vibrations rotate at twice the speed of the primary. See that at 120 degrees spread, with two pistons at TDC, the 4 pistons each contribute 1/2 of what each piston at TDC contributes in the opposite direction. Why? Because sin 30 degrees is 1/2. It comes out of the math. That is why the secondary forces balance out. One cannot understand mathematical things like this without understanding the math and anybody who thinks they are understanding this concept without understanding the math is fooling themselves.
I note your opinion, thank you. My opinion is if somewhat complex math (might not be for you, but it is for many) is used to explain certain things, you immediately lose the interest of 95% of people. That is terrible! I believe it's possible to explain concepts visually so that instead of losing 95% of the audience with 100% correct math, instead 95% of everyone can have some understanding, even if some generalisations are made. I'm not prepping anyone for an engineering exam, and the intended audience is not engineers. The ethos of this channel is I use as little math as possible to explain concepts. I don't care if some don't like it. Many love it.
@@tedarcher9120 Probably because the Allison V-1710 was single stage supercharged, limiting it's high altitude use. We know turbo-supercharging didn't work out for the V12 single engine fighters, so it was probaby faster (war raging on in the meantime) to go for an engine that already had a 2 stage supercharger than to redesign the supercharger of the Allison.
@@LetsGoAviate yeah, but wasn't it faster just to pull the supercharger off a Merlin and stick it on Allison? Packards came out about the same time as two stage Allisons anyway
@@tedarcher9120 I think the 2 stage Allison came out a bit later, the Packard-built Merlin first ran in 1941 already. As far as I know it was actually discussed to use the supercharger of a Merlin on the V-1710 but I guess it was considered more of a "gamble" than the Merlin which has been proven to a larger extent by this time.
If you are using auto engines as the comparison you need to bear a couple of things in mind. An aero-engine is required, and certified, to produce that power continuously up to a rated altitude. The power quoted for auto engines is usually peak horsepower generated on a test dyno for a short time. Also consider the rpm at which the power is produced. The same applies to stationary and marine engines. The power rating is for continuous use.
"...which is a very low state of tune." Right, the consumer grade naturally aspirated LS makes that much power and it is OHV and 2 valves/cylinder. Oh, yeah it is 80 years later. There has been some progress made in material science, combustion engineering, fuels, electronics etc etc etc.
That's why I always say Harley Davidson engine is the worst engine made but even people that own them do not know how it works if they did they would not have bought them.
