Twin-Boom Superplanes... With A Twist!: Mansyu Ki-98 & Mitsubishi J4M
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- Опубликовано: 26 апр 2024
- In this video, we talk about two twin-boom pusher-prop plane designs from late World War 2 Imperial Japan, in the Mansyu Ki-98 and Mitsubishi J4M. We first start by talking about radial engines, how they typically work, and what their advantages and disadvantages are. Then we go into the war situation of Japan from mid-WW2 onward, with mainland Japan increasingly coming under bomber attack. We then look at the Ki-98, its early beginning as a ground attacker, and how the war situation led to it changing to a high altitude fighter and interceptor.
We also look at a similar, almost carbon-copy in the J4M that was intended to fill the same purpose. We talk about their projected incredibly high top speeds and how they had an odd design choice in using an air-cooled radial engine buried behind the cockpit in the body. We talk about why this was an odd choice and how they went about accounting for it. We end by talking about how even if these planes made it to combat, they wouldn't have changed anything about the war.
Do not confuse the RADIAL engine with the ROTARY engine. They look similar when they are not running, but VERY different when they are. With the RADIAL engine, the cylinders and crank case remain stationary, only the crankshaft rotates. They are mostly all 4 cycle engines also. With the ROTARY engine, as the name implies, the whole crankcase and cylinders rotate along with the propeller, and the CRANKSHAFT is stationary and affixed to the body of the airplane. The rotary engines were also mostly 2 stroke. They were popular in World War 1. By World War 2, they were considered obsolete, and radial engines had entirely replaced them except on some very old planes which retained their original engines.
Radial engine cyclinders have fixed positions that radiate from the center of a crankshaft that turns within the engine..
Rotary engine cyclinders, and the propeller, rotate around a crankshaft that is firmly fixed to the enrire aircraft;
The propeller of a rotory engine is attached to the engine. The propeller and engine rotate as one assembly.
Both provide better cooling than inline cylinder engines.
The rotory engine has wicked gyroscopic precession that requires very different piloting skills compared to other airplanes.
I don't think anyone is confused by that, at least on this channel. Interesting tidbit on rotary engines. Early model Mazda automobiles used a rotary engine type known as the Wankel. Little bit different obviously from aero engines, but I found working on them fascinating.
@@rbilleaud The Wankel engine, although termed a "rotary" engine, is an entirely different principle from the rotary aero engines used in the First World War. Those engines had pistons and cylinders, all of which, along with the crankcase, rotated and were attached to the propeller. The crankshaft was fixed to the aircraft's body. The Wankel engine has a fixed body. What rotates is a triangular piece inside geared to the power output shaft. There are no cylinders, per se. It is entirely different. The only similarity is the term "rotary."
@powellmountainmike8853 that's what I kept thinking of. I didn't know there was two types of rotary engines
@@rbilleaud Mazda used the Wankel design of rotary-piston engine for decades (1967 - 2012, plus again starting in 2023), not in its earliest cars, and not just in early models.
The FW190 had just such a cooling fan at the front of its radial, which allowed a tighter cowling with a large spinner. While it ate up significant horsepower, the net benefit was large.
The Japanese were probably aware of the design by the time they started work on these aircraft.
They used cooling fan like that in J2M.
The photo of Ha-211 RU engine shows a cooling fan quite similar to the fan used by the BMW 801 installed on the propeller shaft.
The Germans traded technology for needed resources like metals.
@@enscroggs I thought the picture he showed was a BMW 801! I guess there are only so many ways to design a ducted fan.
The cooling air has quite a lot of energy after picking up heAt from the engine. With the right ducting, it can provide a small but useful but useful amount of thrust, which may have been part of the reasoning behind using this design.
I am not alone in desiring the Pusher Prop configuration ! The sound is in back of you, your front view is not obstructed and you can put all of your weapons Right there !
I absolutely love how they were able to aircool the engine without adding Scoops !
LOVE IT !!
The only Pusher Prop Twin Boom fighter in WW2 period to make production and service was the Swedish Saab 21. It was later converted to carry a jet engine as the Saab 21-R as its configuration was so similar to the DH Vampire and used the same DH Goblin engine.
6:40 photo shows the Ki 94 mockup a push pull design similar to the Dornier Piefel D335
Same thought here. It looks like a push/pull design. And it's Pfeil (Arrow), ;)
Convergent evolution also demonstrates the same principle as "convergent engineering". The laws of nature tend to winnow out the most imaginative ideas from the most effective ones.
I’ve been saying that wartime military development strongly resembles radiated adaptation, it’s an interesting phenomenon
Great point. I’m an evolutionary biologist, but husband in military intel and sims. Ancestors in opposing militaries lol.
But ‘convergent evolution’ is fascinating.
Hopefully you men, 90% of all geniuses will always be you as 90% of retarded, autism for instance, to cure aging and diseases like cancer, Alzheimer’s etc.
The same imagination, scientific method etc, you would be surprised his many cures for ‘A’ actually resulted from research on ‘Z’.
Please boys, keep up your interests and ideas.
@@ashbirk4681 Very true. Furthermore, these wartime developments often carry on less than optimal features for similar reasons seen in biological evolution. Whales drive themselves through the water by stroking their tail flukes vertically, whereas nearly all fish and the extinct Ichthyosaurs employ a horizontal side-to-side motion. Hydrodynamic principles suggest fish are more efficient swimmers on account of their horizontal tail motion. ( The flatfish -- flounders, sole, halibut -- are exceptions as they have traded efficiency for stealth.) Whales, however, have retained a spinal column evolved for fast running on land which doesn't really benefit their totally aquatic lifestyles. The overwhelming trend toward air-cooled radial engines in the Imperial Japanese forces can be viewed in the same light as the mammalian spine.
I must say, I think you may all be al talking balderdash.
Evolution is a matter of random change, blind luck and trial and error. And that is conceding that evolution has a purpose - long term survival. of many species, In fact it has no purpose at all
Engineering design is a matter of ingenuity in service of some Human goal . It is purposive. deliberate and goal driven.
In war of course each side develops new machinery, tactics; exploits opportunities and defends against new threats existing platforms will change
To cite some even clearer examples:
Would you say that a fox is a better inhabitant of English woodland scavenger/hunter niche because its teeth are more evolved than simpler badger's teeth in other words the fox has passed through more near extinction events connected to tooth construction?
Would you say that a Spitfire mk XIX is a better design than a Hurricane Mk III one as a fighter thee other as a fighter bomber - just because 19 is bigger than 3?
oohh dratt. I think I get it now,, you aren't saying they are the same kind of thing. You you're' saying they are analogous. Right?
Because there's nothing whatever the matter with whales tails. From Blues to Orcas they were all doing just fine until humans showed up. No doubt some were on the edge of extinction. There always are some like that , without that preessre there woiuld be no evoliution and no us.
And I take the point about adaptive evolution though beyond the finches i cant think of a good example
Excellent point ☝️
STREET FIGHTER!!!! YEA!!! Awesome analogy!!! And a very cool plane that I've never heard of. Thank you.
Surprised you mentioned a French pusher before a British aircraft. There was a many paper projects and some actual airframes- Vickers Type 161, Boulton Paul P99 & P100, Gloster F18/37.
I did enjoy the video, and I learned something at the same time. Having been born in January of 1942, I have always been interested in the Second World War, and it is gratifying to learn something new about the War. Thank you.
The pictured mock up of the Mansyu seems to have a pusher propellor and a puller propellor?
That's Ki-94-I.
@@Teh0X - maybe so - but it was included with this video -
which would obviously be confusing - specially when one had never heard of the KI-94-I
@@jonniiinferno9098 No doubt about it. Certainly a mistake.
@@jonniiinferno9098 Should have been included in this essay since it was one of the candidate bids for their "wunderwaffesu" fighter. Perhaps he couldn't find enough info or cut it for time, but the pic snuck in?
Your mockup at frame [10:29] is a Pusher-Puller. The two aircraft you're high-lighting are Pushers.
11:36 The Netherlands S-21, Would love to see a video covering that design. I do realize that info on it may be lacking.
This would make a great kit plane project.
But did if fight Godzilla like the Kyushu J7W Shinden?
Nope
Fascinating video. Thank you
great video
The Mitsubishi looks similar to a prop version of the DH Vampire.
Interesting vid. Thank you for posting.
Great Show.
Thanks for the very interesting war bird video.....
Old F-4 II Shoe🇺🇸
Clearly the forerunner of Thunderbird 2! 👍🏻
Thanks for the video. Having a long standing interest in military aviation I have come across these two aircraft but this has added much needed detail.
the engine configuration reminds me of the italian p.119, it wasn't a twin boom but the engine location and type was exactly the same.
they actually test fly it and guess what, had cooling problems, but it still performed decently well, before it had a problem when landing because of the landing gear, sadly it was not repaired because of the armistice.
the chubby fuselage gave the designers a lot of room to put fuel and had a very high range compared to other italian planes
It didn't have a fan inside, and propeller was in front of the plane
Could you do a video on some if those high efficiency hoten gliders or their super sonic concepts
slight side note, that mock up you showed at 11:00 is of the Tachikawa Ki-94-I, not of the Mansyu Ki-98
Never saw these planes. Good information. Thanks
I've always been baffled and fascinated by rotary engines. I don't understand how fuel moves from a fixed gas tank to a spinning set of cylinders. Absolute magic to me.
The crankshaft is hollow. And fuel goes thru there.
Applies to a rotating engine - fuel is fed through the hollow crank - fixed solidly to the aircraft. Radial engines work like your car-engine and only the outputshaft rotates.
It follows that the conrods are also hollow, and the fuel-air mixture comes up through the middle of the piston? I think there's a spring loaded poppet valve in the piston crown.
Many were 2 strokes, or used the principle of passing the mixed fuel/air charge thru the crankcase to be drawn into the pistons from ports.
@@obsidianjane4413 I don't recall coming across any that were two strokes..
Thank you for another informative entertaining video.
I definitely learned something from this video.
Thanks.
🙈🙉🙊 😎 🇺🇸
It is possible that the hot air being expelled from the back, may even have provided some element of thrust. (The Meredith Effect.) It would depend on the integrity of the cowling but as the hot air would have expanded it could very well have had some measurable effect. This could have gone some way to balancing the engine power lost in driving the fan.🤔. An example of this system in action, can be seen in the P51 Mustangs cooling system.
Isn't that a Sopwith Camel at the 0:44 mark within rotary engine?
Yes. The author does not know the difference between a rotary (fixed crankshaft) and a radial (moving crankshaft).
Did the Crntral Powers use rotary engines on warplanes? It might have been a spectacular episode to attack such a warplane with an S.P.A.D. It's 37mm would probably make short work with one good hit on the engine spinning at high rpm!!
@@martkbanjoboy8853 yes, they did. The Fokker Eindekker and Dreidekker both had rotary engines, to name but two.
And at 2:40 its a Texan disguised as a B5N.
Most of the pusher propeller designs had engine cooling issues. For example, Northrop XP-56, Curtiss XP-55, Saab J-21A, Dornier 355, Northrop XB-35, Kyushu J7W1. Convair had to put a lot of effort into getting engine cooling to work, especially at altitude.
The Focke-Wulf Fw-190 demonstrated that a radial engine could be aerodynamically integrated well, recognising that a closely cowled engine was better cooled by forcing air near to the cylinder fins, not just creating drag moving between the cylinders. Copying these ideas Hawker created the Tempest II/Fury/Sea Fury, Grumman F8F.
The radial was also much more damage tolerant. Both the BMW-801 and PW-2800 got their pilots home even after a cylinder was shot off. By contrast a single rifle-calibre bullet through the radiator of a liquid cooled engine could lead to engine shutdown.
Looks like a propeller driven De havilland Vampire
Or SAAB J21
Twin-engine Ki-83 also used Ha-43 engine.
11:39 what exaclly names this s21 ? You have video about him?
at 6:41 - that mock up looks like it has a prop in front as well as in the rear...
Radial and Rotary engines are similar in some respects but VERY different in operation. They do share air cooling as a common feature. Rotary engines were widespread during WWI but were soon replaced by the Radial shortly after.
I’m not sure that the picture of the KI98 mockup is right. There are a couple of significant differences: the tail assembly is a different configuration with a low set tailplane and the fin shape is also different. But the biggest difference is that the mockup has two engines. One in the back and one in the front. It is in fact a photo of the Tachikawa KI94.
Cool designs but with the Pusher prop , begs the Question how did the Pilot get out without being Diced ? ..Good vid.
At 6:42 that photo shows an aircraft with a push/pull configuration strangely.
Saying that air-cooled radials are devoid of a cooling system is a bit of an oversimplification. Besides lubrication, oil also performs a lot of cooling of the internal engine parts, particularly important in air-cooled designs. All these motors are, therefore, equipped with fairly large oil-coolers exposed to the airflow where they create additional drag. It should also be mentioned that many of the WWI radials are actually rotary radials which are a weird and wonderful design in their own right with the crankshaft bolted to the airframe and the prop bolted to crankcase, the whole cylinder assembly rotates along with the prop. Many of them also operate on a two-stroke instead of a four-stroke cycle.
Been thinking about this. If the intake fan worked, it would also have mitigated boundary layer resistance... it might have been super slippery
Yes and the shutters at the rear could have been tuned to produce a net thrust like in a P-51 Mustang. With propeller cuffs the whole design could have become very efficient.
@@stevenborham1584 they were already doing that to late model zeroes
They fan in front of the radial is what the FW 190 used... HP of the engine is also similar - was the engine a copy of the BMW?
In WW1 there were also pusher planes, probably with radial or rotary engines
Ki⭕️ Ha⭕️ 👍
Thank you from Japan
Please sir . . . Can I have some more? On the J7W.
One merely need to look at the cooling issues B-36s suffered from with their six pusher radials, to see some of the issues such designs would have faced had they seen service.
Very cool video as I'd never heard of either aircraft (yes, I did learn something). As a side note, there's a big difference between a radial engine and a rotary engine, as shown in some of the photos early in the video and used extensively in early fighter aircraft.
These are great looking aircraft (if they would have ended up looking like that). Kind of looks a bit like a propeller version of a Vampire.
Do pushers help with elevator control?
The ki 61 had a water cooled engine. Maybe they could have used that motor for these projects? Souped it up a little with a hot cam and fuel injection?
Loving that Streetfighter reference with Blanco. I'm more of a Dhalsim fan. YOGA FLAME!
The plane at 1:38 is a Curtiss P-36 Hawk (aka Curtiss H-75), for those wondering.
en.wikipedia.org/wiki/Curtiss_P-36_Hawk
Yes, thanks. I was wondering. With RAF markings?
@@user-vj7el2wg9b In RAF service they were known as Mohawks. Most of them were used in Burma and India.
@@hamiltonmays4256 Did they actually see front-line service? I kinda doubt whether they ever confronted Japanese Army warplanes. The RAF and RAAF used Brewster Buffaloes over Malaya, 1941-42.
Aloha, going great! Mahalo for your work…
Love the direct P-38 tail copy.
The J4m is a super sleek ship. It would have been better in the Saab 21 niche than the Saab 21 itself. The mid-wing would have reduced the propeller vibration experienced by the Kyushu J7W (less downwash and off-set masking effect). The large passive cooling air inlets would have helped its engine driven fan immensely simultaneousely creating a kind of 'Dynamic soaring' like effect at the rear fuselage. However it would have ultimately needed more power for its design weight, say the likes of the R-3350 size and +2,500hp as she is a fairly big bird.
The SAAB 21 deserves more notice in that it was in service for ~4 years. However it had a water cooled engine. It was also later converted to a jet engine design.
6:40 and 10:26 - - The real prototype from the photo shows a push-pull with front and rear propellers, while the nice color artwork, along the whole video, shows pushers-only.
The J4M reminds me of Thunderbird 2.
My thoughts exactly
It looks to me like the Japanese recognized the superiority of America's P-38 Lightning during World War 2. It's no coincidence that America's top ace all scored his kills while flying the Lightning with its superior nose guns placement. And Japan's top military leader who planned the Pearl Harbor attack was also shot down and killed by a P-38 Lighting.
Spark Plugs (plural, many, multiple), all internal combustion engines used for aircraft have at least TWO spark plugs and TWO ignition systems (two magnetos and two sets of plug leads) as a safety net against failure of one system.
Never heard of the Mansyu, prototype or not it's a pretty cool design
Looks like the SAAB 21.
If we're talking 'unusual Japanese warplanes', how about the Shinden/Shinden Kai?
Quite the fascinating little aircraft...
🍄
The Bristol family of Radials (Hercules, Centaur, ...) did not use poppet valves at all, but rather sleeves. They were generally successful, but also rather unique. 😃My best definition of a true radial would require radially mounted cylinders linked to a single crankshaft.
BTW, there were a number of experimental "fake" radials made up of several inline blocks of cylinders mounted radially, each with its own crankshaft, geared to a common propeller shaft. These would be mostly water cooled...
There's another engineering factor for rotary engines which is usually glossed over. The propellor, cylinders, and crankcase spun around the center of the crankshaft; which was bolted to the firewall. The offset of the master rod was stationary. The pistons, attached to the connecting rods rolled in a circle around the offset the up and down motion being the offset of the two assemblies around the crankshaft. The attraction? Minimal vibration. The pistons scribed a circle around the crank offset, the cylinders scribed a circle around the center of the crank effectively double the offset. Vibration was a big concern with everything held together with glue and wood screws. The torque from all that spinning metal was manageable - barely. Great snap rolls, they were tremendous one way - the other way was a slow turn. Use what yea got ...
I expect the enemy would know which way you would break if attacked from astern, and would be waiting for it !!?
except the at aircraft shown at 0:47 is a rotary not a radial, a rotary works by having its crankshaft stationary and the cylinders fixed to the propellor to act as a flywheel.
Yup. A Sopwith Camel. The issue early on was cooling - with modest speeds of the early aircraft there was insufficient airflow to cool a (later) conventional radial engine so they solved the problem by having the cylinders rotate with the propeller.
How do you feed the fuel to the rotary cylinders?
@@onkelmicke9670 Through the hub.
@@onkelmicke9670the crankshaft is hollow, supplying the engine with a fuel/oil mixture (the oil is for lubrication).
SNCASO SO.8000 Narval?
Rays? Never heard that term used for the cylinders of a radial engine before and couldn't find anything with google either. It is what they are from a geometry point of view but still not used from what I could tell.
Correct - no one uses this terminology for engines. Radial engines have radially-configured cylinders.
Amazingly they had basically invented a turbo fan engine for these aircraft had they only used the fan to supply air to the intake of the power engine!!!
All WW1 engines were rotary, i.e. the crankshaft is bolted to the airframe and the propeller is bolted to the cylinders, so the whole engine spins with the engine. With the later radial engines the cylinders are bolted to the airframe and the propeller is bolted to the crankshaft, so only the propeller and crankshaft spins.
Not all were radials
Not all. The French firm Salmson built water-cooled radial engines with stationary cylinders like WWII radial engines. Anzani also built air-cooled radial engines, up to a 20 cylinder engine good for 200hp in 1913.
That external fan doesn't make sense.
Put the fan on the engine so that it sucks air into bay.
Also have slots protruding into air stream
The J4 -M was in a Movie i seen today called Godzilla minus 1
This aircraft reminds me of a Russian aircraft from about 1940. This aircraft was also a twin boomer with a rear engine in the main fuselage, combined with a pusher prop, together with heavy cannon armament at the front of the main fuselage & tricycle landing gear, but a ramjet contained within each of the 2 boom. So during take off, landing & cruising, only the main engine & prop operated, but in combat the 2 ramjets came in play, giving way over 400mph performance in 1940. However with Operation Barbarossa & the transfer of Russia’s aircraft industry being transferred east of the Urals, Russia cancelled all designs that didn't look like they would be finalised & fully sorted within 6 months. Also by having all the guns in the middle it would have all the benefits of zero deflection gunnery, meaning better accuracy, easier training & much simply sights to boot,
Call them by the technical term used by people who have to work on them. Big ole roundie rounds.
Makes me wonder if one could make more efficient use of a pusher like this utilizing ducting geometry and/or the venturi effect to recoup some of the cooling air as thrust akin to a high bypass turbofan. I'm sure it would still be less optimal than traditional designs, but it would be a good project for undergrads.
The wind god looks like Ed Roth art.
Fascintating. I wonder if Japan had any help on these from Germany? Thank you for this video. 👍🏻👍🏻
They'd have known about the BMW801 with its fan, and the Ki-61 used a licence-built DB601
@@thhseeking thank you. ☺️
In the third year of fighting the Americans and having come up against P38s, but already beginning to suffer from materials shortages, this looks like the Japanese attempt at keeping up technologically but developing good inline engines would have taken years they didn't have. Nice video 👍
Yeah, I dont think the engines wouldve been adequately cooled that way. Germany tried much the same thing on the Fw190, with early prototypes having a cowling that left a mere slit between it and the propeller hub, but a fan, much like the one on the Ha-211, would fix it. It didnt. Also, the fan is so similar that honestly I was wondering if you were trying to sell a picture of a BMW801 off as a Japanese engine. In the end the cowling had to be opened up more, if for no other reason than that the pilots legs were being baked.
But I also honestly see a very simple fix here. Just cut down the front fuselages width by making it slab-sided around the cockpit, so that around where the slots are you can keep it round and use the gap between the two as a giant air scoop on both sides. With that I could see a chance of it getting cooled properly.
WWI was mostly "rotary" engines. WWII were radials.
The only advantage of such pusher configuration is seamless conversion to Jet engine.
I'll be that guy.
Aircraft engines like the radial pictured have two plugs per cylinder and separate magitoes for each. Two plugs per cylinder, two magnetos.
The biggest problem the Japanese had with engines was that their fuel was lower octane. It was because they had much less oil to start with, so if they refined it to octane levels the Allies used they wouldn't have nearly enough. The Germans had a similar problem.
"These kinds of engines were incredibly common in the early days of aviation!"
Proceeds to show a plane with a rotary engine.
Which, technically, is a radial, but doesn't work at all according to the principle just demonstrated.
0:55 whats that? radials always have odd number of cylinders per row but this one has 6.
Four-stroke radials with a single row have an odd number of cylinders so they can have a regular firing interval. multi-row radials don't need that, and there are some four-stroke multi-row radials with an even number of cylinders per row; they need separate camshafts for each bank of cylinders because the common cam rings only work with an odd number of cylinders.
But the Anzani at 0:55 does not have 6 cylinders per row - it is a 2-row engine with 3 cylinders per row. The rows are very closely spaced (possible due to large gaps between cylinders with only 3 cylinders in a row) so it looks like a single-row engine unless you look carefully.
@@brianb-p6586 oh you are right. it really is 2 row engine. also can you name any radial with even number of cylinders per row?
This looks very much like the post war French Navy ground attack plane that was cancelled before operational use.
It doesn't matter how cool your interceptors are if you don't have the fuel to deploy them.
Radials powered the United States through WW2 in the Sherman tank. That’s why they had such a high profile for a tank.
I would argue that for Japan everything after midway was second half of war as production costs outpaced supply.
I prefer opposed piston engine . but even jets soon will be obsolete .
Re radial engines: Kurt Tank: Hold my beer.
You show a Sopwith Camel, The Sopwith Camel had a rotary engine, not radial.
Most radials had oil cooling along with air cooling.
There was also the issue of bailing out..into a meat chopper.
I would like to know how well one of these with a radial powered ducted fan setup would work. Basically a jet engine but stupid.
They make electric ducted fan RC model Jet's, how well would it work if you replaced the pusher prop with a ducted fan setup?
You illustrate the concept of the radial engine by a photo of a rotary engined fighter. A different concept.
Who would ever call the radially arranged cylinders "rays"? Or is this the previously unknown Ray-Deal engine?
IHYLS, sir, you *_gotta_* do a video about the De Schelde S.21 (11:32). It looks too weird and wacky not to cover. 😁❤ Even a really short video (or a YT Short) would do!
18 cylinders? So it had 1 cylinder every 20°? Imagine how smooth that thing ran. Especially since these were 2 strokes.
Yes, a cylinder every 40° in one row, and a second staggered to alternate with the front row. But like the vast majority of radials the Mitsubishi engines were four-strokes (with their design copied from Armstrong Siddeley and the Pratt & Whitney models), so only half of the cylinders fire on each revolution, and so there is a firing every 40° of crankshaft rotation.
For more detailed information about the Mitsubishi Ha-43 (also known as Ha-211), you might be interested in the Old Machine Press article "Mitsubishi [Ha-43] (A20 / Ha-211 / MK9) Aircraft Engine". I suspect that some of the stills in this video came from the Old Machine Press article, or from the same source as that article.
@@brianb-p6586 it's a 4 stroke? Isn't that a nightmare to have to put valves all around?
Wonder how the secondary imbalance in a radial engine acts
@@Rose_Butterfly98 Yes, almost all radials are 4-strokes. The conventional design uses pushrods run by cam rings that are placed around the crankshaft and gear-driven at half crankshaft speed. The pushrods push rocker arms to operate the overhead valves, just like any overhead valve pushrod engine (which the majority of engines built until the world switched to overhead camshafts). Some engines (such as GM and Ford gasoline truck engines) still use pushrods this way. It's a lot of parts, but in any four-stroke most of the complication is the valvetrain.
same design concept + jet engine = Vampire
A better comparison would be the SAAB J21 that to my knowledge was the only WWII pusher prop design to enter service, it was later converted to J21R spec using the same jet engine as the Vampire
if you had to bail out there is a good chance that the prop would have ground you up,,akin to an ejection seat in a helicopter.