The Forgotten HYPER Aircraft Engines of WWII
In the early 30s, in the prelude to WWII, the US Army and the US navy needed production engines that could meet or exceed the 1 hp per cubic inch benchmark. At the time, that power output had only been achieved by several purpose-built racing engines, but no reproducible production engine had yet fulfilled this need. As a result, the US government financed several “high-performance” or hyper-engine projects, and in today’s video, we’ll be taking a look at some of these incredible, forgotten pieces of engineering…
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00:00 - Start
00:27 - XI-2220
04:32 - Lycoming 7755
06:50 - Wright - R-2160
08:22 - Pratt & Whitney Sleeve Valves
09:40 - Conclusions
5:36 Trying to picture them screaming over the radio "THATS VTEC KICKING IN YO!!" 😂
Great video. At the National Museum of the USAF (Dayton OH) there is a partial cutaway of an R-4360, with components that slowly move. A Very complicated engine, like the ones you show. It is easy to imagine how a B-36 could have to shut down one or more engines. I think of all the engineers and mechanics working in the 40's to solve all the problems, without CAD or CAE tools we have today. It is pretty amazing what they accomplished. From the Wiki B-36 article: As engine fires occurred with the B-36's radial engines, some crews humorously changed the aircraft's slogan from "six turning, four burning" into "two turning, two burning, two smoking, two choking and two more unaccounted for"
I had to adjust the magnetos on a 4360 for my faa practical test for my power plant certificate!
Despite being a mechanic my whole life and tinkering with all kinds of machines it’s still hard for me to wrap my head around the technology of these massive engines. Thank you for sharing this information it was very interesting.
It’s rather interesting that none of the US engine manufacturers tried with 2-stroke designs. Rolls-Royce, on the other hand, developed the Crecy which was pretty much the crackhead cousin of the Merlin.
The Crecy ran on the test stand but that time the piston aero engine was being superseded by the gas turbine.
You cant use 2 stroke engines They need turbo and 2 stroke have no valves so the pressurized air will pass and the engine will lose a Ton of power. Plus you must regolate fuel mix relative to altitude and 2 stroke cant mantain mix precision
An excellent comparison
Look up the junkers ju-86p and the jump 207 engine
@@RealNotallGaming Don't tell Electro Motive that .
I always found the Continental I-1430 hyper engine to be interesting and would love to see you make a video on it. Love your work, your effort is greatly appreciated!
Well done video. Ive worked on many ww2 era engines as a A&P and am always amazed at the quality of machine work and engineering involved. Amazing machines.
I used to work with the last 2160 at the museum it lives in. Such a wild engine with an incredibly weird story behind it. Thank you for covering these weird franken-engines!
Sometimes I wonder what a high displacement, high cylinder count engine could put out with the knowledge we have now.
Yes, I have always wanted to see someone remake or reproduce a Merlin, or R-2800 with modern technology.
@@OGBootleg that'll unfortunately never happen. Over the past few years it's become increasingly clear that time is running out for the ICE.
@@Alexander_Snowden In aviation? Absolutely not.
@@PistonAvatarGuy I meant more in terms of automobiles. But once the ICE powered car has been defeated its only a matter of time before the fun police look to aviation. Remember, there are powerful people that have skin in the game against the ICE.
Dante Giacosa, Fiat engineer, worked on aviation engines before projecting car engines, said that the limit of aviation engines was the number of revs due to the fact that was needed a bigger heavy gearbox in order to limit propeller rpm if the engine doubled the conventional rpm speed… we know that power output is related with rpm speed… however the power for cubic inch was the same of an engine car, thanks to the compressor, at normal revs in use in those days aviation engines… so the solution was to increase cylinders number…
56 years I’ve obsessed over aviation. Sitting on the tailgate of the old Dodge Custom 880 station wagon, on the edge of Edwards AFB watching airplanes that later became legends thunder down down runways and blaze past overhead. That was 1964-1967. I was hooked at age 4, I was a junkie by age 7. The addiction led to my acquiring AIDS later in life, contracting the Aviation Induced Divorce Syndrome more than once…. I say that to say this: You have a good, solid, repeatable talent for researching and narration of truly intriguing or fun aviation facts. You are a “dealer” with good dope🧐. Thanks for providing a great outlet for we that have the same affliction, we can’t get enough! Do you have a Patreon gig going?
Good Read 😂
I think thats one of the funniest aviation anecdotes I've heard!
You may at least mention the Jumo 222 since its the by far most insane "hyper-engine" of WW2.
These Engines are beautiful peices of Gear, it's crazy to think what could have been.
Glad I found your channel. Amazing content and research. Thank you
Excellent video. Great engineering history with plenty of detail. Thanks a lot, Colin ( UK )
Thanks for throwing light on these fascinating engines I'd never come across before..
These are complex engines for their time. Even today it is a marvel of engineering. Wow. You covered this topic well sir. Thank u for your efforts it was interesting.
Seems incomplete without mention of Bristol, they already had highly mature sleeve valve designs and provided the fixes for Napier. The omission of the Centaurus is regrettable as it had far more potential that the PW and CR big radials and provided excellent post war service even in its low state of tune.
That was a really interesting video! the pacing was good too, didn't feel any longer or shorter than it needed to be!
I always wondered what the engine looked like that went into the XP-47H. Thanks, great video.
By far the biggest influence on power output during the 1940s was fuel octane rating, the Merlin doubled in power mainly because of the ever increasing octane/performance number of the fuel available.
Well done, at last someone finally describes the XR-7755's 2-speed propeller reducer gear-box! It wasn't LYCOMING's first either.
Great work. . . Thank you 👍
That last clip was the best!
Amazing content as allways camt wait for more
With regard to the issues that Napier had with their sleeve valve engine, the Sabre, a big factor in their solving them was help they received from Bristol, who had already been through them with their sleeve valve radials, which they had been developing from several years earlier.
Napier was punching the holes in the sleeves, Bristol was machining them. That was the key. Solving the problem involved importing Cincinnati Milling machines from the US. This was a German style problem of not enough machine tools.
05:15 - I believe that this is the actual unit on display at the Air & Space Museum in Dulles, VA! It's unreal to see it up close!
Very nice video. The Lycoming XR-7755 was tested at the propulsion laboratory at Wright-Patterson Air Force Base in Dayton, Ohio. When the testing program ended, instead returning the engine to Lycoming, it was burried in the ground somewhere on base and nobody has figured out where exactually it was burried. Lycoming has already expressed interest in getting this engine back to their factory if only it can be found. Think Lycoming only built 3 examples, one was a mock up and the other two were running examples. The only known surviving XR-7755 is in the Smithsonian.
There's a team whose sole goal is to find hidden objects. The crew is currently working on Oak Island.
@@outlet6989 funny
For years there was a rumor that there were R-2800s buried somewhere on the Nash Motors property in Kenosha.
Beautiful documentary footages here that mean so much now.
As my boss in the small design firm that I work for is often saying, we aren’t trying to reinvent the wheel, just trying to make it more efficient
I'm not saying this to create an argument, just to be honest. The Daimler DB 600 and Yumo line were 10 years ahead (technologically speaking) with any internal combustion engine that the allies have manufactured.
That would be a very fair and accurate statement, there is no doubt that Germany made the most technically advanced engines during WW2.
If you look at the power output per litre of the Merlin and Sabre they were always infront of their German counterparts.
Thanks. I had no idea about these engines
Like your stuff and your a good documentary reader
Pratt & Whitney radial engines first flown in 1940 are still being used on some DC 3 aircraft. The Wasp and double Wasp are still being overhauled.
man i just got off work and I see flight uploaded. today was a good day
Fascinating corner of WWII arcana, and there seems to be a lot of it coming out these days on KZhead and elsewhere, all of it interesting. For example, Nazis and the occult are worth looking into. Good, pertinent data. Nice job.
Fascinating. Especially how they ever work at all.
Fantastic engineering
Ha! i've got pictures of one of these Wright R-2160s from the backyard of Walter Soplata in the 70s and 80s. It was located between the two halves of the B36 fuselage.
Servicing any of those engines must have been a nightmare.
cool well done
I live in Williamsport Pennsylvania, Lycoming County, home of Lycoming engines.
Very Cool
I like the fact that you speak fast enough that I don't feel the need to up the speed to 1.25 or 1.5. Nice video.
Thanks. I am used to the word "hyper" being reserved for engines whose dev started in the early 1930's rather the late '30's early 40's. Still, I love the video. Have you read Graham White's book "Tornado". I'm pretty sure White and the "Journal of the Aircraft Engine Hist Society" are both gone, but they are still cool sources. Go Dojo!!
I should check out the tornado book. I’ve only read Allied Aircraft Engines as of right now.
Tornado’s author is actually Kimble McCutcheon.
l am Sub'ed....Excellent video.....Thanks Shoe🇺🇸
01:33 very sophisticated test bench 👍
@Flight Dojo >>> FWIW: That _Lycoming_ engine that was slated for the *B-36 Peacemaker* was new info for me. I thought the air-cooled radials they used were the original choice. I wonder how the *B-36* would have fared with the _Lycoming_ engines.
Good content, new subber...
The radial made a lot more sense . It could withstand hits and develop the power. A 10,000 hp prop driven aircraft was still limited by prop top speed .
While I agree with you regarding the radials making a LOT more sense for most applications, the prop isn’t as big of an issue as many think. Most of the fighters towards the end of the war were reaching the limit of prop diameter and torque / p-factor, and many began attempting contra-rotating prop designs. The TU-95 works just fine with 15,000hp engines driving props. If you go with a complex scimitar you can achieve similar results such as the 11,000hp engine on the A400m. But yeah, you couldn’t have a single prop on a single-engine plane making those HP numbers, the p-factor would just be outrageous.
Radials lack sufficient cooling above 2,000 kW to have made more sense. Which was why 4-row radials like the ASh-73, R-4360 and even R-3350 suffered from reliability issues due to overheating of back cylinders and the excess power being eaten up to provide for cooling. Thereby increasing cooling drag which accounts for a sizeable percentage of total drag especially at higher speeds.
it is what is known as "mission creep" thing get changed mid stream causing unnecessary delays and costs. still going on today
Amaing engineering none the less.
It would be great if the blueprints for these hyper engines would be available. To the public.
Early B-36's were not underpowered; The Jet packs were added to enable a "dash" suitable for a bombing run; Almost the entire flight environment was powered by the 4360's exclusively.
I wonder what would have come about if the turbojet engines hadnt been developed for another 20 years or so.
Great look at the classics - I had never heard the 4360 was chosen over the 7755 due to politics when there were more practical reasons. Also the early B-36’s were not grossly underpowered, there being many early demonstrations that met payload and range goals - the jets were added mostly to allow higher speed on target runs.
Well, full load, hot and/or high density altitude takeoffs in an early B36 were a very chancy affair. The aircraft required extremely long takeoff runs even under the best conditions, so I'd say far all practical purposes the early 36s were indeed underpowered and in fact, the later ones were not much better than marginal either. This is all pretty well known and documented, but I'll add I had an uncle, career USAF who flew 36s. Pretty much disliked them for all the above reasons.
All true - but that underpowered definition would apply to all other prop bombers as well. I didn’t have a B-36 uncle but was historian for a B-36 retired group and knew several A/Cs along with B-36 test pilot Beryl Erickson. None of them ever singled it out as underpowered.
@@johnwatson3948 The begs the question then - why were the four J47s added if the early 36s weren't underpowered ? Everything I have ever read indicated that the 36 power/weight ratio was very marginal at best and that the R4360s were not particularly reliable which compounded the problem. All that being said, I think we must recognize that despite the meddling of politicians the B36 did its job well, holding the line until the 47 and 52 came into use.
I tend to believe that the Wasp Major was chosen because it worked, and was available in series production (also used on the F2G, XP-72, AM, XF-11, XF-12, Martin Mars, and a slew of transports). And based on wartime experience with several hundred thousand P&W engines, Air Force brass knew that Pratt had sweated all the details on their smaller radials.
Yes I think you’re right that’s certainly what was going on. The 4360 was already proven while the 7755 needed further development and required a liquid cooling radiator system which would take up space and I don’t think is included in its power-to- weight ratio. The contra-prop system it needed might also have caused some concern. Apparently was not practical for the 7755 to be used in the pusher mode - one early 1940’s B-36 wind tunnel model shows very large forward mounted stubs on the wing leading edge - the only evidence I’ve seen that the 7755 was considered.
Just think what we could have had by December 1941 if the Army had allowed the Lockheed L-133 to go into product, a jet fighter capable of 600 mph, Kelly Johnson and Nathan Price were way ahead of the times.
The Lockheed L-133 never existed, it was only a proposal, the L-1000 engine wasn't completed until 1946 and proved a disappointment.
Shame the Napier sabre isn't mentioned, unstable as it was, till Bristol got involved. As I remember it was 2000 bhp without a supercharger. Edit. Just found your videos on the Sabre. My mistake. Apologies
Great video, the germans had similar programs to build the ultimate aero engine, as far as i understand, nobody did a video those engines. So, here is your friendly reminder that such a video might attraktiv a lot of attention. :)
there is little data on those and most were abandoned before or soon after jet engine started production. also those engines mostly were much smaller than american.
wonderful
All I could think was imagine trying to change the plugs on the 2160! Or trying to diagnose a misfire on a 42 cylinder engine
The Americans sort of missed the bus with some of these. On the other hand, there were always increasing demands for engine power but they seemed to be done on occasions, independently of aircraft development. Perhaps the best example of this was the sleeve valve Pratt & Whitney. All that seems to have proved was that Pratt & Whitney was capable of producing a sleeve valve engine. Compared to the Sabre, it wasn't all that well executed. The Sabre was intended to provide the densest power generation for the lowest possible frontal area. The P&W, while doubtless well-built, is the kind of shape that would have given aircraft designers nightmares. The Wright R-2160 looks a lot like the Jump 222. In contrast to the Pratt & Whitney, this is a much more sympathetic design in streamlining terms. But I would imagine tha, like the Jump, the rear cylinders ran a lot hotter than the front ones (front and rear being interchangeable for the B-36... you get the idea).
Great!
What I don't get is that none of them used 4 valve per cylinder designs while they wanted to maximize output (for the 4 stroke engines). Going from 2 to 4 valves seems to be one of the most test and tried ways to improve output (already long operational in existing engines like the RR merlin, etc.)
Very nice vid, I am a student of Gregs aircraft and autos as well
Something like the Armstrong Whitworth Deerhound aircooled radial poppet valve piston engine which used ducted air passages for cooling. The test aircraft was sabotaged on it's maiden flight, then it was cancelled before any of it's true potential was realised and assessed. At that time everything had to go into Merlin production and that was that!.
The Chrysler engine had hemispherical combustion chambers. Putting two valves in a hemispherical combustion chamber pushrod motor with push rods and rocker shafts requires an excessively long rocker for the exhaust valve. It would be almost impossible to put four valves in a pushrod hemispherical combustion chamber and retain rocker shafts. But Chrysler, as they sometimes tended to do for a couple of decades, could get fixated on one particular aspect of engineering "rightness" even though the advantage precluded other positive strategies or even simplicity. For instance Chrysler held onto left-hand thread lug nuts for the left side wheels for years after Ford and GM abandoned them as unnecessary because of lug nut design advances.
don't 4 valves collide unless you put intakes on opposite sides ( and exhaust on opposite ). Also the rocker arm will collide with the next cylinder, unless you rotate by some odd 20° . VW engines have their exhaust valves point away from the engine. I guess to keep the heat away.
And nuts and bolts that required wrenches in 32nds of an inch. 19/32 and 25/32 if I recall correctly.
Franklin attempted such an engine also. The O-805.
"Come on, Henderson, wear your goggles, it'll make for a more authentic picture!"
love those chrysler units
Higher octane automobile fuel, after the war, was a side effect of needing better aviation fuels for boost and performance
Talk about dodging the bullet. Those things look like they required lot of TLC to keep working "reliably". So glad the turbojet was created and perfectioned soon after.
Not soon after. The first steps had been taken, just not reliable enough. But yeah, these pistons have things moving around (or to and fro) in horrifying numbers. And it all needs racing plane quality oil. That can not be right. Suppose you got a 24 cylinder engine, that means 120 valves, if you want real power. Oops. Is that wisdom? It is beautiful, sure, I love it. Wouldn't it be great, if somebody designs a modern version of those 40-ish liter 24 cylinder engine in a W-configuration? I guess there are racing ships or aerobatic planes that would need such a monster. A kevlar carbon Spitfire, maybe?
@@voornaam3191 "soon" after not used properly. But in the grand scheme of things it was a short period, JMHO.
The R-2160 would have sounded glorious.
WRONG title: The Forgotten !US-MADE! HYPER Aircraft Engines of WWII
i love ww2 engines. opposing pistons, sleeve valves, 2 stroke diesels, super and turbo charged condensation cooling, ect. its just an amateur engineers dream
It would be interesting if military budget giant piston engine research/technology never died out. Imagine what they would have today if they weren’t replaced with the turbine
This list might also need the Wright R4090 & Napier E124 based on the Nomad
Capacities shown/mentioned in litres would've been handy so that this video was relevant to the rest of the world, not just the USA.
All These engines are just incredible pieces of engineering and manufacturing
All they had to do is wait as the British will give them the Merlin.
The Napier was a different animal in that it had 24 cyl's for higher RPM because of the lower reciprocating mass and sleeve valves to allow as much opening for air flow as forced induction could supply. Problems? Pilots needed to be on oxygen before they started it because of exhaust leaks. Napier had the ringer on the drawing boards at the end of The War but as another commentator has stated the jet had already taken over. Their Deltic engine powered rail engines and our Mekong Navy untill the 80's.
I love the Sabre, it's an outrageous engine and the sleeve.valve.Bristol Centaurus which I have seen flying in a Seafury. The Secret Horsepower Race identifies that the sleeve.valve could not take high boost pressure because it would.deform and squeeze lube oil out with predictable consequences. You could not.compensate by making it thicker because then heat transfer for cooling became an issue ..Clipping as the sleeve transitioned the ports was also possible.problem at.excessive boost.
GM wanted over 2000 changes to that Chrysler16 cylinder HEMI engine series-get or check out the book- the Gen 1 Hemi's (1950's) had a direct connection to the aircraft engine.
George Huebner was also involved in Chrysler's investigation into gas turbine powered automobiles.
Wow!
Vtec in the 40s..wow
interesting !
An interesting future video would be to just concentrate on turbo, supercharging and turbo compound development.
He said prelude 🎉 "buwaaaa.. **down shift** BAHWaaAAAAAAA!!!!!" 😅
normal radials kinda just got good by the end of the war. p47 was flying around with 2400hp form just a regular relitivly compact aircooled radial. and by then the wave of the future was the jet.
As a huge fan of the sleek inline engined planes like Spitfire, Mustang, and the mighty Tempest, the R-2800 was probably the best piston aero engine of the war (if not of all time). Good power/weight, lots of power, famously reliable (including no vulnerable liquid cooling system). If it had been paired with a FW190A style low drag installation it could have outclassed the inlines in the European theater.
I think it's pointless to make the comparison, each type has its good and bad points . As an aircraft designer you would consider all the factors and variables then choose accordingly. The mustang could do Berlin return the P47 could not. But large air-cooled radials were the likely the most numerous Bomber engine . I recommend a book called the Secret Horsepower race if you are interested in the deeper technicalities of thje various design permutations, it explodes a few myths too if.you will excuse the pun. ,
Compact? Um I guess
@@invertedv12powerhouse77 compared to these massive hyper engines. No cooling system either.
@@invertedv12powerhouse77 . It's all relative I suppose but if you wanted low profile drag inline was the way which usually meant liquid cooled.
Beautiful engineering but I wouldn't wanna have to maintain any of these in field conditions
Lots of aero engines were very successful with hemi heads and 2 valves, some making 1 hp/ ci. These included all the radials. Manufacturing 2x the stellite valves, seats, sodium cooled 2pc valves, bronze guides, and the hardened seats along with the overly complex valve gear wasn't a CNC pushbutton affair and required tungsten tools all major time, serviceability, stocking, and strategic materials use being turned into chips on a floor somewhere to discarded in a few hours of operation. The valve gear on any engine is responsible for most failures and is the most expensive and time consuming to repair. Hemi was chosen because it eaisily allowed two central plugs and offered the best detonation resistance and strength of any design. Still does. Thats why a 500ci Top Fuel Hemi makes 12,000 hp!
Your last sentence is absolute bullshit. The reason why top fuel dragsters make 12000 hp is mainly the fuel and the oversized roots blower pushing air at as much as 4 Bar or more into the block. I'll give you credit for noticing the detonation benefit of hemispheric combustion chambers but that about sums up the the usefullness of that design. 2 valves per cylinder is just to limiting, that's why every rate engine today is a 4 valve engine. Top fuel dragsters are 2 valve engines, because they are literal automotive dinosaurs, except for the ignition system. A top fuel dragster can have only 2 valves, because the fuel has so much oxygen bound in itselfe, that the power limiting factor isn't oxygen anymorem it's hydrolocking (as the carburettors dump so much fuel in the cylinders, that, the piston compressing liquid instead of mostly gases, is a real danger).
Read carefully and dump the anger, and you will see that I NEVER said two valves made superior power at all. that would be BS! what I said was that the hemispheric combustion chambers ALLOWED big pressure (=power) without deformation, detonation, and have reduced flame travel. they also have better heat dissapation (ESPECIALLY critical in high hp air cooled radials!) The WW2 air war became an octane requirements battle. I am fully cognizant of the fact that a specially developed 4 valve hemi (or some pent roof) engine could do better in SOME areas. Chrysler realized this and developed one. It is possible. Look at the angled rockers on a radial. Overhead cams can also do this, but it's way complex, an engineering nightmare and high wear. Someone is always so vehemently angry at the hemi, which wasn't a mopar design anyway, and will ax grind against it no matter what to the point of adding words I didn't use. I also know that "modern" 4 valves and some polyspherical heads do very well or better in SOME applications, but in testing had too little meat between seats for top fuel. And deformed or detonated. Even hemi heads are physically consumed in the chambers in nitro apps. No other engine was ever drug out of a crane, grandma's imperial, or a boat and went like a hemi! Ported 1955 331 heads can flow 400+ cfm and will handle MORE abuse than any other production design Just ask Don Garlits (I have!) The only reason a few other standard production pedestrian engines beat a 392 in the early days was poor traction. Use a REGULAR production cast block and heads that arent a millions dollar special order engineering experiment that you have to be blood related to management to obtain, and it's all hemi. My Dragsters blown Keith Black Hemi has no major components at all, not directly bolt on to an original 426 save bore size. And my 1958 Dodge D 700 semi's 354 can be put into the 5 second range! But would have to sacrifice its blower, or nitro, or add up to 1500 lb to compete with a wedge legally in the NHRA in some classes. No one ever sees the chicanery that is legislated in. But it does allow for more variety and thats ok, we will haul more weight, let them have the blower, and give them an extra motor on their tractor, run restrictors, adhere to ci limits imposed on us and still be waiting for them at the finish line most days. I realize my KB has been surpassed by BAE, etc. the goal of the NHRA was to not have only 3 factory backed millionaires racing in top fuel. So, the best suitable, obtainable, aftermarket supported, and SAFE engine design was mandated. APPLICATION, COST, and EXPECTATION dictate success. Hemis have already made the 1/4 mile tracks obsolete, been completely crapped on by NASCAR rules, limited in top alchol compared to others, limited to one LESS engine than any other in some multi engine NTPA classes, and were the cause of CONGRESSIONAL mandates to manufacturers to stop wasting resources to try to beat it! but Hemis are still the most popular in many classes regardless of whose block is under them. what more do we need? Im not a bench racer wet behind the ears! I have failure analysis, R&D, metallurgy, engineering, racing, circle track, pulling, aviation, dyno operator, engine builder, and QC, experience, continuing from 3 generations. We even built our own pistons and ground cams in house. However, Im sure I could learn things from you too, and I'm sure you have more knowledge some areas. thats fine. Let's learn from each other. I'm not right about everything. I don't want a pissing contest, everyone just gets wet! . Your point would be valid if I had said that. Best regards.
@@danielsacks7152 The hemi-design does not inherently allow for higher pressure, or more heat dissipation, if anything, it'quite the opposite. Everything close to a hemispheric has less arwa per voulme, there dissipates less heat. The hemispheric design also doesn't lend itselfe much to high compression ratios, because of the dome like design. The hemispheric design essentially allowed for ideal sparkplug placement for 2 valve engines, without sharp metal corners (wich overheat and lead to knocking). It was a good compromise between simplicity, reliability and poweroutput. The Hemispheric chamber was very popular in supercharged engine designs beacuse of these reasons. However, if you got the technology, to fit 4 valves reliably into a combustion chamber, it will always be superior in terms of power, especially, because the rooftop design of 4 valve cylinderheads offer less small features and more surface area to volume (wich both reduce knock). If you go into the realm of direct injected engines, a 4 valve design is even better, because it allows, in contrast to a 2 valve design, for a more ideal combination of sparkplug and injector placement, while using a maximum valve area. Also, on that not, cylinder pressure does not equal power, if anything, it equals torque, minus blowby, fricion and heat dissipation. Counterintuatively, you will find, that high powered engines, especially supercharged engines, wich are limited by fuel quality, have almost always a lower cylinder pressure than compareable high torque engines. This has to do with, what you correctly pointed out befor, knocking. What a high power engine really wants, is a lot of fuel air mixture and high cyclic rate, compression ratio and cylinder pressure often play a secondary role, the best example for that logic are 2 stroke engines, they have unbelievably high power to displacement ratios compared to 4 strokes, of up to 400 hp/L (naturally aspirated i might add) in the days of the GP500.
Yes, as stated, I agree. What is really needed is opposed piston direct injected double acting 2 cycles or similar like most big diesels in ships from 100 years ago. All of this has been done 70 to 100 yrs ago, but recently more perfected and available due to metallurgy and CNC. What's needed in competition "automotive" engines is more smaller cylinders, short strokes, long rods and more valves at higher rpms. But when it hits the end of the track with a 40,000lb sled behind it, and pulls down it would fall on its butt torque wise and not have enough rotating mass to start the load or torque to accelerate it quickly. Those dinosaurs have a practical place. When discussing heat dissapation i was referring to AIR COOLED engines mandated by the navy and for ground attack and bombers due to combat survivability. The large area between the valves can be covered in fins, and heat causes little distortion, again, knock reduction. Supercharger metallurgy allowed the surpassing of the mechanical limits of the engines regardless of valve layout in WW2 detonation was used often to push German fighters to destruction even with water methanol just by chasing them with a P47 or similar. We denied them higher octane fuels. The sphere is an unalterable natural choice for reflecting the MOST of the heat into the chamber where it's needed and not into the cooling systems. It is superior for detonation according to piston manufacturers who laughed at me when i asked if quench would help a Hemi they said "hell no, they dont need it!" They could have took my money and built them anyway. Chrysler chose it based on a test mule single cylinder variable compression engine when post war low octane was all that was available. that clearly demonstrated that for practical rpms it was far superior detonation wise than any other. The wright 3350 made more than 1 hp / ci at only 2700 rpms. As do several others. Yes, a high rpm 4 valve would do better, but If it's my butt on that constellation in 1952 crossing the atlantic eating peanuts, I'll take the cubes, simplicity and low rpms! Same thing the the guys who build 4 valve merlin, and allisons say to this day. Over water, gimme a round engine! Poor maintenance, round hemi! Cost and time to overhaul and extended TBO, 2 valve hemi. That won't change anytime soon, but hey, we have jets now! Which still haven't beat hemis on the pull track or dragstrips. But have at Bonneville. They just recently unseated the hemis 40yr record for piston engines there, just to prove a non hemi could. But guess what? Those pourpose built, as the company owners say, "nothings interchangeable or dimensionally the same as a Chevy" companies offer those engines as hemis that make even more power. Take two identical motors, and increase the cylinder pressure on one and its more powerful. But only if everything is equal. I built a blown engine because of the lower pressures, better manners and longevity. Blowers have outlasted many engines so my $$ doesn't all go in the scrap hopper! Theres absolutely no difference between torque and hp. HP is TQ at rpm. 1 ftlb is 1 hp at 5250 rpm no matter what. That's why all dyno graphs cross there. No WW2 areo motor "laid down" at high rpms from airflow on dynos they kept making more. They blew up first. Any hemi will also. But make less than a short stroke multi valve v12. But, man, I gotta pay for it! Direct gasoline injection was used on hemi R4360s on the B36 in the fifties (so was antilock brakes!) I despise "Cronological Predjudice" that completely trashes anything older throwing out the baby with the bath water, not realizing they came at least half a century too late to claim "modern" as if thats a religion. Heck, flatheads still have applications. Dinosaur or not, I don't want to go bare fisted against a T-Rex on equal terms! Theres not many competitions where Hemis aren't severely limited rules wise because unrestricted they overpower all practical chassis, safety equipment and tracks already. Thats the difference between possible and practical and gives the Dinosaur a very modern application especially when supercharged. You simply wont get cost effective gains going to 4 valves most places it is still used. Formula cars, indy, small ci imports and bikes have already moved on long ago due to much of what you say. I still like watching Suzuki 3 cyl 2 strokes at the track!
Hemispherical engines make less power than a 4-valve Pentroof combustion chamber... and that why hemis are obsolete technology in automobile manufacturing. Top Fuel is a Vintage class motorsports series, only the 1964 426 Chrysler is allowed to compete...
Excellent video! Keep making 'em .... they're "engine-porn" for us gearheads.
I find it a bit bizarre that they focused on hp/cu in. rather than power to weight or specific fuel consumption (hp hour/gal). Hp/cu in. is useless (for an aircraft) if the engine is heavy or uses a lot of fuel (also heavy). Hp/displacement is a racers metric where the displacement of the engine is limited by class rules. Its not really relevant to aircraft design.
People who make these types of videos generally don't get that, because most of their experiences in life is with automobiles they tend to focus on HP/displacement instead of HP/weight which is equally as important with aircraft, they're both important, even if you could keep the weight the same designing a larger displacement engine in an aircraft the increased size is just as detrimental as increased weight, one of the reasons that the Rolls-Royce Griffon was vastly superior to the Merlin was because it was something like 30% more powerful but was only around 12% bigger. A milestone in aircraft engine's was the Pratt&Whitney R2800, none of these types of videos ever mentions that it was the first aircraft engine to hit 1 HP per pound. Another thing that can be deceiving about aircraft engine's is the power to weight of liquid cooled aircraft engine's, everyone always wants to run to Wikipedia and look up the power to weight ratings listed for different aircraft engine's especially the Merlin, but what they fail to realize is that because of the variations of it's use in different aircraft the weight of the cooling system and coolant is never included, that rating is always a comparison of power to the dry weight of one of those engine's, minus the radiator and associated cooling lines, on average add 250 lbs to what's listed then rework the math for power to weight to get a more accurate picture, wherein an air-cooled aircraft engine is listing the actual power to weight for one.
Sounds like a classic case of 'mission creep'. How are you supposed to design something when they keep moving the goal posts?
Too bad there isn’t any footage with sound of any of these. I’ve read that the XR -7755 was heard well outside the test cell into the nearby neighborhoods and businesses. And the Wright Tornado didn’t have even-firing banks of six, so it’s exhaust note is unknown. Incidentally, it had roughly the same bore and stroke as a Chevrolet 409. Very oversquare, unusual for radials. Graham White has (had?) a Continental IV-1420, another one of the “Hypers”, that’s ground runner. It turned out to be unexpectedly loud.
It is absolutely mind blowing to realize that the US manufacturing industry was able to design and produce these incredibly complex engines. Disregarding for a moment the fact that this country has outsourced almost all of its industry, the fact that these engines were developed 80 YEARS ago, without the use of CADD is almost difficult to believe but that’s because we think that society has “progressed” since then…
But they were failures and didn't work. Luckily the British were gracious enough to let the US copy their jet engines under license.
I mean, a modern turboprop will do similar horsepower for less than a third of the weight of a WW2 piston engine. Don’t even get me started on jets lol. Hell, a modern 1500hp bugatti car engine weighs like 900lbs and has literally a tenth of the fuel consumption of a rolls royce merlin or similar. Engine technology has come a long way, we’ve absolutely progressed on that front.
@@MotorcycleWrites True, with the provisos that it run continuously for at least 100 hours at maximum horsepower at an altitude of 25k ft. and output shaft speed that would keep a 14 ft propeller under supersonic tip speed at that altitude, plus various requirements like dual ignition and other mechanical necessities for aviation use. Unfortunately the reduction gearbox and ancillaries would also add so much weight and mass that the Varon engine would need substantial overbuilding to accommodate the thrust and load requirements. Still would be a good thing to see in action. The perpetual rabbit hole full of cans of worms. My 2 bob’s worth. Take care.
Piston engines were ultimately a dead-end in large capacity forms, due to weight and complexity.
If the jets hadn't been developed,there is no idea where these big engines could have gone with better materials and fuels
The propeller was the most limiting thing as far as speed
Will you be doing the insane Napier Nomad?
Vtec before vtec. Very cool
What about the P.@ W R 1830? The Navy bombshell that may have been used in Earharts Electra? OR AM I JUST IMAGINING THAT?
Great video. I've often wondered why you'd want an H block engine in a fighter i.e. they tend to be heavy and complex. However the Sabre was a good engine so there must have been some benefit. Maybe H allowed for a higher RPM than a V engine?
I would guess the main benefit of an H block engine would be the power per frontal area allowing for a low drag airframe.
Napier's sliding sleeve design had it's power sweet spot around 4000 RPM vs radial and V-type engines around 2500 RPM. That then drove propeller design and gearboxes to accommodate the change. Look up the Napier Saber engine on KZhead. At the end of the day, sliding sleeve engines were too finicky to mass produce.
If the alternative is a traditional V configuration, I guess with 24 cylinders, like the Sabre, you end up with a very long crankshaft and engine block, leading to unpleasant vibration modes etc.? Also might be difficult fitting such a long engine into a typical airframe.
Good point. Also a long crankshaft probably couldn't handle the torque - like when the straight 8 went out of favour in cars.
@@jbepsilon perhaps but the Sabre engine with it's "H" configuration was in reality extremely complex with very high oil consumption with it's sleeve valves and very high fuel consumption. Doesn't make much sense sense considering that the late variants of the Rolls-Royce Merlin and the even more savage Rolls-Royce Griffon was just marginally less powerful than the Sabre engine. Those engines were truly marvelous feat of engineering and personally I always loved those engines but it was much easier and cheaper to produce the jet engines...
Very interesting, but when you talked about the Napier Sabre you missed out Frank Halford who was at Napier , Fedden was at Bristol and of course Ricardo worked with them both en.wikipedia.org/wiki/Frank_Halford