The Rise & Fall of the Radial Airplane Engine - History & Technical

[@LetsGoAviate]

WWII Aero V12 Engines Design Explained : kzbin.info/www/bejne/iqubp4ekoZKjd7c The Inline 6 Airplane Engine : kzbin.info/www/bejne/iaaciIFmhc5jatU Adept V6 vs Boxer 6 : kzbin.info/www/bejne/iH_cZ5eCaLqketU

[@earlbenge8904]

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[@DonFahquidmi]

I just want to let you know how much I appreciate the time and effort that you put into your work. I really appreciate the links to upstream sources that you provided in the video description. And last but never least, I love that you use your own voice to narrate your videos instead of AI. Your own voice communicates a passion for the subject that AI simply cannot match.

[@LetsGoAviate]

@@DonFahquidmi Thanks for the comment, it means a lot if the vast amount of time that goes into a video like this is appreciated.

[@Ikaros-Von-Kreta]

The first powered flight was in Germany, 1901.

[@gfodale]

I knew radials always had an odd number of cylinders. This is the first time I've heard why. Thank you!

[@mpetersen6]

Some radials were built with even numbers of cylinders per row. Wright built two different 12 cylinder two row radials Bristol iirc developed a 16 cylinder with two rows of 8. Plus two stroke radials can be even or odd

[@turbo32coupe]

Flew a Stearman with a Continental W670 for 30 years. The engine didn't leak unless it sat for a long time. Sold it to a museum In Madrid, Spain. I still miss the sound. My airplane was in the Movie "The Tuskegee Airmen". BTW, after an hour or two, the vibration made my stick hand numb.

[@LetsGoAviate]

That's incredible! Yeah I have flown in a Stearman and a T6 Texan (known as a Harvard around here), on both the vibrations were noticible but I didn't make much of it at the time. Thanks for the comment.

[@michaelfrench3396]

I'm only making this comment cuz I think as the maker of video you'll see it. Could you do a video on the application of radial engines in helicopters? Because you missed a big big post-war world war II niche that radial engines filled. It wasn't until the UH one Iroquois that turbines were actually put on helicopters in a military application

[@LetsGoAviate]

​@@michaelfrench3396 Noted, thanks. Indeed radials did hang on for helicopter powerplant options for longer after the war than it did for airplanes.

[@88SC]

@@michaelfrench3396 Right? Who else would love to stand next to a Sikorsky S-56 while it starts and takes off?

[@nurhasanal953]

​@michaelfrench3396

[@timmercer6710]

Was told by a retired Boeing engineer years ago that radial piston -bore size maxed out due to the expanding flame front at the point of ignition in the cylinder not being able to complete the combustion before the exhaust stroke .

[@allisfarmall7946]

yes around 6 inches or so for cooling and dentonation trouble thts Pratt never went past 5.75 inch bore Bristol had the same bore but a 7 inch stroke

[@nerd1000ify]

This problem would have been aggrevated by the use of hemispherical combustion chambers on most radials, they were needed to allow large valves for airflow but provided relatively little turbulence to speed up combustion. Bristol's sleeve valve engines were better in that regard, but had many of their own issues...

[@scottgriffin2005]

Two spark plugs is the solution to that

[@nerd1000ify]

@@scottgriffin2005 they all already have two, dual plugs is standard on aircraft engines for redundancy. The plugs are powered by independent magnetos, one mag can fail and the engine will still run with some reduction of power.

[@mpetersen6]

​@@allisfarmall7946 The largest radials l know of were built as stationary engines for pumping stations and power houses. Built by Nordberg they featured a bore and stroke of 14" x 14”. Built in 11 and 12 cylinder variants. They were also unusual in that they featured no master rod

[@88SC]

The secondary imbalance became a big thing on 18 cylinder radials, which being 180° out of phase between the two rows, resulted in a wobble motion in which the engine constantly tried to change the propeller’s plane of rotation. Pratt and Whitney as well as Wright ended up installing rotating counterweights (not exactly “shafts”) to counter the forces. It was killing propeller shaft bearings. The effect was discovered in around 1938 or 1939 when the R-2800 and R-3350 were in development.

[@danbenson7587]

Regret my disagreement. A single row radial is well balanced in primary and secondary. Facing the engine, If one draws lines connecting the piston wrist pins ..(approximately the piston CG’s) a circular figure emerges. This balanced by the crank Counterweight. A twin row is two balanced single row radials bolted together. There is No rocking couple as witnessed in a two cylinder in line. Single row radials (R1820) have bifilar dampers… What causes whacky radial balance problems is 1. the link rods/pistons do not have true motion, thus don’t hit TDC corresponding to crank. So the link pin locations on the master rod are clocked. Great for timing, not so good for 2ndry balance. Enter bifilar damper. 2. In a twin row, 2nd engine row is clocked (for cooling) relative to the first row. The 2nd row can’t be oriented optimally to counteract 1st row. “Old Machine Press” (googable) has a paper on developing the R2800 crankshaft and working through its balance problems. OMPress is a gold mine for gearheads. Cheers D

[@88SC]

@@danbenson7587 Our source is the same! Yes, different acceleration of the pistons due to the link pins not having the same center as the crank pin, plus the pendulum (ish) motion of the master rod. Maybe not identical to secondary imbalance/vibration, but it was solved by the 2x crankshaft speed geared counterweights. By the way, where is William Pearce, he hasn’t updated OMP for quite a while?

[@jonathansteadman7935]

Which is why a competent Sopwith Camel pilot could use the gyroscopic effect to face the aircraft 180° when an enemy was behind.

[@danbenson7587]

@@jonathansteadman7935 The WW1 rotating radials, yes. WW2 fixed radials not really. Gyroscopic precession is the actor here. WW1 engines and props made a greater proportion of mass (25%] of the plane so precession effects stronger. WW2 planes precession mainly from the prop (1-2%).

[@danbenson7587]

@@88SC sorry, I don’t know Mr. Pearce. I hit on OMPress about once a year trolling for an old engine concept to mate with modern control, EFI, etc.

[@cavecookie1]

There's nothing like the sound of a radial. Whenever one flies over, I'm in the yard looking...and my neighbor's in his yard, doing the same thing! LOL!

[@johndoe-so2ef]

Me too!

[@captainretro373]

You have obviously never heard a spitfire fly over

[@cavecookie1]

So, because I like the sound of a radial engine, you are able to assume that I have never heard a Merlin engine? Your conclusion is not only NOT obvious, a logician would say it is irrational. Anyway, my comment was concerning radial engines on a video featuring radial engines. Why would I bring up Spitfires?@@captainretro373

[@brianmccarthy1029]

I’m lucky enough to hear DHC-3 Otters and DH-2 Beavers take off from a lake on a regular basis.

[@cavecookie1]

Very nice! I live in the mountain west, and there are lots of fire fighting aircraft in the area, especially in the summer, and lots of those have radials. My neighbor that I mentioned used to fly Beavers, that's why he's always there with me, spotting planes!@@brianmccarthy1029

[@CamillaLyn6]

i love radials, honestly, best sounding engine for planes ever

[@powerwagon3731]

I remember assembling a W 670 in A & P school in the 1980s, it was an awesome experience. We took a trip last summer from Homer Alaska to Brooks Falls on a Beaver which is radial powered. The sights, sounds and low frequency vibrations were great! There is a rotary engine motorcycle from the twenties with the engine mounted in the front wheel too. Thanks for a great video!

[@DonFahquidmi]

We disassembled and assembled a W-670 at Colorado Aero Tech.

[@SteveAubrey1762]

NOTHING sounds like " aviation" like a radial engine...to my ears😊

[@eottoe2001]

This blew my mind. I had no idea all the engineering that went into the radial engine. I flew in a four-prop plane as a kid and I remember the vibration and sound. Now I know why. What incredibly smart people. I get why it took Wright Aviation so long to work out all the kinks in their engines in the 1930s and 1940s. All this was done with slide rules and vellum.

[@powerwagon3731]

I’m an old architect and I still use vellum. Ha Ha!

[@eottoe2001]

@@powerwagon3731 Y A Y !

[@theislander-sj1kq]

I have used vellum and mylar working as a draftsman at a shipyard in 70s.

[@SFSunsetguy]

I stumbled onto your video as I am building a Corsair model plane and the engine was not something I was familiar with. I found your wealth of information and presentation skills outstanding. While dealing with only the external parts of the engine build, I was fascinated to understand how complex yet elegant this engine is. Keep educating us, it great information. Thanks.

[@bobjacobson858]

Thanks for this informative video. My father was a fighter pilot in WW II, flying a P-38. Although this fighter had liquid-cooled engines, my father had flown various kinds of planes in training, etc., and he taught me quite a bit about about the different kinds of aircraft and their engines. When I was in graduate school in Athens, GA during the middle and late 1970s, I usually went home to the NYC area by air. There were commuter flights from Athens to Atlanta, and during the first few years I was in Georgia, I flew on these Martin 404 aircraft piloted by Southern Airways (even though most people seemed to avoid them!) because I recognized these aircraft as remnants of an era that would soon end. I used to sit where I could watch the exhaust manifold of an engine (which would glow, especially during takeoff) as well as the flames from the exhaust pipe (yellow due to the richer fuel mixture used during takeoff, then blue during the complete combustion when a leaner mixture was used during cruising). I had an altimeter, and brought it along during flights. I don't believe these planes were pressurized, but they didn't fly very high--my altimeter usually read about 5000-6000 feet. The larger jet aircraft, being pressurized, read about 8000 feet although they flew at altitudes 3 to 5 times that. As I recall, the smaller turboprops, which replaced the Martin 404s, typically flew at about 15,000 feet and were pressurized. Before the days of terrorist attacks, one could sit up front in a turboprop commuter and watch the pilots at work (it wasn't interesting to watch the engines with those aircraft)--I knew the altitude because I could see the plane's altimeter. Now I take my road atlas and track the progress of the flight--and sometimes I see interesting things on the ground that I decide to visit by car later on!

[@LetsGoAviate]

That is awesome! Your father must have had some stories. Thanks for sharing.

[@bobjacobson858]

@@LetsGoAviate You're most welcome. Yes, he said that at one point, he was sitting in New Guinea "feeding" the local mosquitoes, and decided he would be thankful for every day he lived after that. He made it to halfway past his 90th birthday.

[@nerd1000ify]

Here's an interesting connection: my great grandfather was also in New Guinea during WW2, he was an infantryman in the Australian army. I have a model of a P-38 that he cast from aluminium at some time during or after the war, my grandmother told me he might have got the metal from a crashed Zero, though that's almost certainly not true. I guess it's possible he actually saw your dad's plane flying by at some point. Certainly he must have seen P-38s around given that they inspired him to make a model of one.

[@bobjacobson858]

@@nerd1000ify Thanks! As the saying goes, it's a small world. I want to thank your great-grandfather posthumously for his service in helping to win this war for both our freedom-loving countries and many others.

[@nerd1000ify]

@@bobjacobson858 likewise, thanks to your old man for his service.

[@julesjames593]

Thank you! I've got Wasps on Beavers outside my window many times per day. Excellent historical perspective.

[@clavo3352]

Beautiful video. As an old shade tree mechanic Most of what I learned was by word of mouth and by rebuilding motors. It was a real treat to view this video about radial engines. Dad bought me a basket full of motorcycle parts in 1973. It was a 1968 Honda CL 350. I had the motor back in the frame and the motor running by about 7 PM. I later learned that its engine layout was nearly identical to an 1940s John Deere Model G Tractor!

[@jayreiter268]

The main component beside the master rod that makes the radial possible is the cam ring. You should devote a hole video explaining it. The cam ring can turn either with or opposite engine rotation. The direction is determined by the geometrically possible number of lobes. A 9 cylinder will run with a 4 lobe cam ring turning opposite engine rotation at 1/8 speed. Or a 5 lobe turning 1/10 speed with engine rotation. It is the cam ring geometric relationship that determines the alternating firing order. The master rod and articulating rod relationship cause a slight timing and stroke length difference in the articulating rod cylinders. Timing is usually cured by a compensated breaker cam magneto. Ignition timing should be made with a properly wired magneto set to the master rod cylinder. That cylinder can be any convenient location.. On a M14P it is #4. The crankshaft counterweights usually have internal vibration dampers. The odd number of cylinders and other differences give the radial that sound. A little pedantic??

[@Thankz4sharing]

Pedantic is fully appropriate here. M14P?

[@saylormalan]

Dear, being an amateur mechanic and a student of piston aero engines, I really liked your post about the valve cam ring of radial engines. Interestingly, the small difference in stroke and timing that exists between the master connecting rod and the articulated connecting rods. I didn't know that detail. I agree with the friend about a video explaining the cam ring of these engines. It is completely different from in-line or V-shaped engines. One interesting thing about radial engines is that they are known as big oil guzzlers.

[@jayreiter268]

@@Thankz4sharing The Vedeneyev M14P is a Russian nine-cylinder 600 cubic inch/10 liter radial..

[@jayreiter268]

The stroke and timing effect is hard to visualize. It is caused because the articulating rod pins travel an elliptical path as the master rod turns around the crank pin. The timing effect is in the order of about + and -3 degrees. That depends on what side the cylinder is on. This is accounted for with a compensated master rod or a compensated magneto. The engines I have worked had compensated magnetos. This information is not widely published as these engine are no longer of commercial interest.

[@saylormalan]

​​@@jayreiter268Greetings from Brazil. I have some doubts about the incredible radial aeroengines. Could you enlighten me? 1) Is the valve opening and closing diagram (angles) similar to the diagrams used in automobiles, which are optimized to increase power/performance? 2) Using the compensated magneto mentioned above, does the power/performance increase significantly? I really appreciate your attention.

[@chrismulligan6987]

My compliments. I've always appreciated the technologies of the era. Your video has certainly helped me understand better the radial engine; thank you.

[@Carstuff111]

The radial engine is one of my favorite aircraft engines. As beautiful as, and as much as I love planes like the P-51 and Spitfire with their Merlin engines, water cooled V12s do sound great, but the radials sound absolutely BRUTAL and it is glorious. THE best sounding engine to me, to date, is the is the Pratt & Whitney R-2800 Double Wasp, and more to the point, as it is installed in the F4U Corsair. Heard a F6F Hellcat fire up, and it was a great sound, but when the Corsair started, it had all the attention. I was about 50 yards away and could feel, every, single, cylinder when they fired. From start up, I could count how many cylinders it was running on just from the thump in my chest. When it later screamed and roared passed us at likely well over 300 MPH, I could STILL feel the engine pounding me in the chest! I could hear the sound of FiFi the B-29 as she flew by from a couple of miles away and she still made a great noise too. I just realized, I have heard way more radials than I had originally thought......and most of them without being at airshows with the exception of the F4U and F6F.

[@tauncfester3022]

The Bristol Centaurus sleeve valve is remembered for having a very interesting exhaust note.

[@ronjon7942]

Oh wow, the paint job on the Corsair at 10:55 is flawless. So striking! Beautiful!

[@fsodn]

6:21 Oh wow! I always wondered but never knew how radials handled valve lifting. Now I know. That's cool, and the animation is very nice.

[@martinsuter3531]

About those Lawrence radials. Beside making radial aircraft engines, in WWII Lawrence also built some miniaturized radial engines of about 10 or 15 horsepower to power B17 and B29 APUs. Unlike radial aircraft engine the Lawrence APU engines had a vertical crankshaft with the cylinders arraigned around it in a horizontal position.

[@VincentComet-l8e]

That large frontal area was quite a handicap for an aeroplane engine. For that reason radials had been thought to be unsuitable for high-performance fighter, but Kurt Tank turned all that on its head by showing the way with the ingeniously smoothed-out nose of his outstanding FW190.

[@aker1993]

Hey the us navy have been doing that since the late 30s to early 40s.

[@marckyle5895]

@@aker1993 IIRC, the USN never used an inline on a carrier routinely. They went straight from radial to turbojet and turboprop. Even the Ryan Fireball was a radial when the streamlining of a inline would really have helped the jet improve performance. Besides. the additional storage space for coolant/prestone storage in order to service them would have meant something else getting reduced and there's no way that was gonna happen.

[@jhschmidMD4]

The aero cowl used by Tank was a modification of the already existing NACA cowling developed in the US before the war. The radial engine that BMW developed for the FW190 (BMW 801) was a descendant of an American design (Pratt & Whitney Hornet), which was built under license by BMW in the 1930's. The Americans, Japanese, French, and others were all developing radial engines for fighter planes (mostly for navy use), before Kurt Tank got around to the FW190. Germany has many great WW2 designs, and many engineering fists, but this was not one of them - they were later than most to this party.

[@nerd1000ify]

The biggest innovations on the Fw 190's engine installation were not the cowl itself but the use of a gear driven cooling fan and the 'swept back' ejector exhausts that were aimed out through the cooling gills at the back of the cowl. Both features aided airflow at low speed and allowed the cowl to be somewhat smaller, with a narrower inlet. The Allies certainly took notes, as the swept back exhausts appeared on some later Allied designs (e.g. the Tempest II) and CAC in Australia copied the cooling fan for their proposed upgraded model of the CAC Boomerang.

[@massmike11]

Nope it’s biggest innovation has to be the engine control system. It was nearly a fadic in analog form.

[@andrewgkorol]

Brilliant video, I always prefer detailed engineering analysis to over simplified efforts targeted at the mass market

[@thomasmaxam8771]

Excellent job with this presentation. Happily, RC model airplane enthusiasts can buy 3, 5, 7 and 9 cylinder radials from 15 cc to 800cc from Saito, UMS, Moki and Valach. That 800 cc was not a typo! Many of them run well and sound big like the full size engines.

[@chipsawdust5816]

There's a shop in Grangeville, ID that repairs and overhauls radial engines. They have so many radial engine parts there it boggles the mind. Most radials are destined for antiques and special interest airplanes. Hardly anyone uses them commercially anymore, although there are some out there. Great video, thank you.

[@lucianene7741]

01:15 By looking at the beautiful geometry of the rotary radial, one can understand the sheer genius of the concept. The cylinders and the pistons and connecting rods assembly form two eccentric flywheels with no reciprocating motion whatsoever in relation to the frame of the aircraft. This translates to ZERO vibrations, which was important with the flimsy wood-and-canvas early airframes.

[@tsbrownie]

I used to fly 2 and sometimes 3 bank radials. They had 2 cylinders per bank. ;)

[@joecserna]

This video popped into my feed and you got all 15 minutes and 5 seconds, sir. Subscribed.

[@LetsGoAviate]

Thanks, appreciated!

[@joecserna]

@@LetsGoAviate it appears you have quite the catalogue I need to catch up on 👍nice

[@GGigabiteM]

The limitations of rotary engines didn't stop them from trying. Various manufacturers tried weird and terrifying designs to try and work around the power limitations of the rotary engine. Siemens-Halske had their SH.III, which was a single row 11 cylinder rotary of 160 HP. In an effort to try and cancel out the P factor, they geared the back of the engine so the crankshaft and engine block would rotate equally in opposite directions. Gnome et Rhone had several terrifying dual row rotaries of 14 and 18 cylinders, and one extremely terrifying four row rotary of 28 cylinders. Thankfully none of these were mass produced. Can you imagine almost a thousand pounds of engine rotating at 1300 RPM? I would want to be nowhere near it. Sadly owing to their obscurity, it's hard to find any pictures of them, though they do exist. There is one example of a dual row rotary at the National Air and Space Museum.

[@kettlebellcarnivore-vr5cw]

Ive been lucky to live in Yellowknife the past 8 years. Regularly get to see DC-3's/C-47's, C-46's and CL-215's. Rare birds!

[@powerwagon3731]

DC-3 and Beavers still flying in Alaska too!

[@Thankz4sharing]

High lubricating oil consumption by air-cooled radial engines is also worth noting. I was in charge of lowest level line maintenance of a Navy T-28 Trojan in the early 1970's. My not too reliable memory is that more than a gallon per hour was normal at low power setting and much more than that at (rarely used) high power use. The 1,425 hp Wright R-1820 Cyclone in a T-28 had a huge oil tank. Sorry I've forgotten just how many gallons. The very expensive oil changes were determined by regularly sending samples to a lab for analysis, not by calendar interval or engine hours.

[@ronjon7942]

Eureka. Now I understand the concept of the master rod. Thanks.

[@stevewhalen6973]

Thanks! , I've always been fascinated by them but now thanks to you I understand them. They're quite a mechanical miracle design and so efficient power to weight wise . To hear them running on takeoffs is a purely majestic sound .

[@LetsGoAviate]

Thank you!

[@molly_mallard]

Thank you for this very informative video. I loved it! There were also non overhead valve radials that used a sleeve instead. My grandfather was an RCAF mechanic during WW2 and he told me about them.

[@Jody-kt9ev]

Good video. I have read that one issue in keeping the old radial engines going, such as on a DC 3, etc. is finding the high octane Avgas they use. This Avgas is getting harder and harder to find. Hence the success of the Bassler Turbo Conversion company.

[@bwyseymail]

Low octane, time for water injection.

[@partymanau]

Love those radials. The sound, the smoke, the ritual of starting...... magic in metal.

[@whitewittock]

Glad the algorithm showed me this video! Would like to hear more about wartime planes and their engines

[@frederickking1660]

You forgot oil spewing. Man but I do love the sound.

[@liztaylor3825]

Another nice feature is caused by the 'every other cylinder' firing order. Any piston on its downward power stroke, is more or less diametrically opposite the piston on its compression stroke, thus the downing piston directly pushes the upgoing piston, rather than imparting the torque through a couple of 90 degree bends, as with an in line engine layout.

[@mooremax]

Awesome video and great explanation of the engine balance!

[@jkoval7160]

Changed mine at 10,000 miles. Saw the mark inside the rim, but just threw them on the static balancer to confirm it was the heavy spot. Replaced with OEM Bridgestones. No weight needed on front wheel, 14 grams on the rear wheel.

[@shack2635]

@LetsGoAviate Nice Job!! Well done! I have R-670 (a variant of the W-670) on my airplane. I love it, probably for the deep guttural sound it makes!! Your presentation of the nuances of the engineering were well explained and made me appreciate my engine even more! Thank You!

[@tomhill4003]

great explanation of radial engines! i've long been fascinated with them, and am still getting a grasp on the engineering principles behind them. Thanks!

[@babboon5764]

What a superbly clear explanation Kudos 👍

[@danbenson7587]

In addition to inlet restrictions, what killed the rotary radial was piston wear from Corliolis acceleration.

[@DavidMScott-cs8pp]

During WW2 Canada built many Anson dual engine bomb and gunnery training aircraft for use in the RCAF Commonwealth Air Training program. The Canadians cut a deal with Jacobs of USA for their radials and had good success with the type. Jacobs never got the recognition because P&W and Wright engines were the choice of the USAF.

[@johnkelly7264]

This is brilliant! Really well presented. Love the detailed explanations. Definitely subbed here!

[@drizler]

Those 4 cyl boxers are real shakers . I ran one for 20 years , an 0200 Continental. I went flying a few times either a guy who had an old 272 Cessna with an 0300. More or less the same as mine with 2 more cylinders. Wow was that baby smooth 👍🏻

[@rescue270]

Go fly a 175 with the geared GO-300 engine. Cruises at 3100 rpm. Now THAT'S a smooth ride.

[@bwyseymail]

If a 4 cyl boxer shakes at speed it means the pistons and rods are not balanced, I built several VW Beetle engines back in the day and balanced the pistons and rods within a gram or two. Very smooth.

[@barryduff5058]

​@@bwyseymailcould that be that a beetle is only 1600cc (96 CI) while an 0360 is 5900cc?

[@Igeltod]

@@barryduff5058 no the smaller boxers can definitely be shaky too if not optimised

[@ArneChristianRosenfeldt]

@@bwyseymailit’s smooth compared to an inline-4 in a golf. But rough compare to 6 cylinders. Why do people build 90° V6 ? F1 . If I destroke an old US 90° V6, does it get smooth?

[@wirralnomad]

The Worlds "first powered/motorised flight" occurred in 1899 in the UK, it just so happened to be that the Worlds "first powered/motorised plane crash" happened, the majority of people don't even know that the Wright Brothers were not the "first people to fly a motorised aeroplane, the Wright Brothers were just the first to successfully land!

[@oml81mm]

A mention of the use of sleeve valves in the different engine layouts might be useful. Thank you for the excellent video btw.

[@glidercoach]

I recognised that accent and confirmed it in your bio. I have a long history in S. Africa. 😊

[@robinj.9329]

Yup! All true. In my own experience radials of 5 cylinders were scarce and small. The 7 or 9 cylinder types more common. And "double-row" engines had 14 or 18 cylinders! Some of the last, large, fast and Luxurious propeller Airliners used 4 of these BIG, POWERFUL radials ! The DC-6, DC-7, and Lockheed Super Constellation 👌.

[@marckyle5895]

I liked the 5 cylinders, they looked so good on the Ryan ST. Much better looking than the Cessna's flat lycoming if ya gotta stick cylinders out in the air to cool them instead of adding a cowling.

[@stephenpowstinger733]

The B-36 used six massive 28-cylinder engines (plus four jet), which I heard mechanics found challenging to maintain.

[@tomhill4003]

A great and informative video! I've always been fascinated with radial engines. Thanks for the walk-through!

[@TriumphDoc]

You are simply awesome man. I can’t believe I just found your channel. Brilliant explanations and diagrams and narration. Thank you!

[@carlmontney7916]

There's nothing quite like the sound of radio aircraft engines once you hear one you always know when you hear another one. I went with my wife to an airshow years ago in Glendale Arizona. Put on by what they called the Confederate Air Force back then. One of the aircraft they had there was a B-17. I wish I could remember what aircraft it was but it was a very long time ago. I remember being in the crowd of people walking around and all of a sudden I heard the sound of those big radials starting to fire up and I told my wife the B-17 here today is going to fly soon. She said How do you know? I said the engines are running, I know that sound. Sure enough about 5 minutes later the organizers came down and cleared the area where we were all looking at the aircraft that were on static display. It turned out we had actually been walking on the taxiway the B-17 was going to come down so they moved us all out of the way. It was pretty impressive watching that thing taxi by and those R-1820 Cyclone 9 radials were loud! Very exciting. All I can wonder was how thunderous it must have been at all the British Air bases when you had hundreds of those B-17s taking off.

[@mpetersen6]

There have been radials built with all link rods and no master rod. One system uses a gear fixed to the crankcase that mates to a pinion gear. The pinion gear is mounted on a shaft. A second pinion gear mates to a gear on the centerline of the crank throw. Another system uses two fixed connecting rods mounted on the rod carrier. Both eystems were used by the Nordberg Corporation of Milwaukee on their large stationary radials in 11 and 12 cylinder single configuration. Used in power house and pumping stations to hese engines feature 14"/350mm bores and strokes. See Old Machine Press for details.

[@TickleFingers]

The rotary design is interesting in the fact that it turned reciprocation into rotation without the main issue of a reciprocating engine, the acceleration, deceleration and instant change in direction of the linear motion. I wonder what a 2 stroke design would have yielded over the 4 stroke. No valve train, each rotation was a power stroke for all cylinders, etc. Were there ever any 2 stroke rotaries?

[@jackx4311]

I think the drawback would be the need for some kind of compressor or charging piston to pressurise the incoming charge, and force it through the transfer ports into the cylinder. Most petrol 2-strokes use crankcase compression to achieve this, but it means that in the case of a two or three cylinder engine, you need seals on the crankshaft between each pair of cylinders, so that each cylinder has its own crankcase, which is pressurised at the right time. As far as I can find out, the only possibility of a rotary 2-stroke would be something based on a Wankel engine. In a rotary engine, all cylinders share the same crankcase, so it cannot be used to for primary compression. The only way it could work would be to adopt the same system used on some British 2-stroke diesels (such as Fodens, and Napier Deltics), where you have either a mechanically driven Rootes-type supercharger, or an exhaust driven turbo charger to provide a source of compressed air for the inlet. Any such addition to the rotary engine would have added so much extra complexity and, critically, extra weight, to what was in essence a simple and lightweight engine. One of the main factors behind the success of the Wright Flyer was that the Wright's fully grasped what was critical about aircraft engines at that time. The power output was important, obviously; what was far more important was the *power-to-weight* ratio - a point where the rotary engine really scored. In WWI, the 24.9 litre Bentley BR.2 rotary engine gave 250 HP, with a dry weight of 490 lbs. In the same period, the inline 14.2 litre Rolls-Royce Falcon gave 288 HP, but weighed 715 lbs! To sum up; the Bentley rotary put out 25% more power per pound weight - a massive advantage. HTH.

[@darylcjackson]

Excellent mix of history and technical. Thanks!

[@awesomedn]

Second row of cylinders creates a rocking couple, since two rows are not in the same plane

[@slehar]

Wow! Depth of knowledge! Excellence in presentation! Bravo!

[@peceed]

Check R-2800 - it had balance shafts integrated in the valvetrain area iirc.

[@bingosunnoon9341]

I did production overhaul of Wasp Juniors in Africa for a while. I can assemble a pressure carburetor with my eyes closed.

[@christianweagle6253]

"Wasps Junior"

[@georgejleonard9410]

Thank you for a walk down back in history Jaco

[@joejones4296]

Excellent. Thank you.

[@ypaulbrown]

thesis a wonderful description of the Radial engine, thank you so much....Paul in Florida

[@josephpacchetti5997]

This is a great channel, glad I found it, subscribed on first video I watched. THX 👍🛩

[@Desmouffe]

Love these engines...

[@alexanderdeburdegala4609]

I just ran into your channel, nicely done, I appreciate how in depth you go, and yet make it easy to understand. I am also glad you're not some AI generated channel.

[@Orangepilldispencer]

Thank you so much for your amazing explanation and in depth knowledge.

[@wiredforstereo]

Probably the best application is front prop Part 103, with the little 3 cylinder radials. It's just about the best possible option, with a light weight short engine swinging a really big prop with relatively low speeds.

[@rescue270]

These engines are called radials because their cylinders are mounted radially on the crankcase. Rotary engines are also radials. Rotary Radial and Fixed Radial. The first radials were rotary engines designed to be mounted within the wheel of early motorcycles. ...and, yes, some radials did use camshafts rather than cam rings. A typical Kinner R-540 five-cylinder radial has five pairs of small, single-cam shafts for each cylinder

[@imtheonevanhalen1557]

What he isn't mentioning is the fact that the cylinders below 180 degrees of the crankshaft centerline were notorious for fouling spark plugs on start up.....if you were lucky the plugs would clean from AV gas pulling into the cylinder! Ever seen vids of guys pulling the huge props around before starting? Trying to avoid this constant problem.

[@Rns555]

BMW was the craziest aircraft engine manufacture of it's time no doubt

[@johncrispin2118]

Thankyou, super graphics . I suppose time limits left no chance to mention of the Bristol Radials in particular the sleeve valvers reducing frontal area, eg ( Hercules) 14 cyl two row, nor the BMW 801 which powered the FW 190. Ohv but featuring the fan to help cool the second row.

[@jbepsilon]

It's hard to make an apples to apples comparison, but the lower diameter advantage is not as high as one might first think, if it even exists at all. See www.enginehistory.org/members/articles/Sleeve.pdf

[@CharlesParmelee]

Good video - I learned a few things. I have wondered why radial engines always have an odd number of cylinders in each row. Many do not know that radial air-cooled engines were used in tanks - like the Sherman in WW2.

[@scottfw7169]

And the M3 Stuart too. Or that one available radial engine brand was Guiberson which were diesel.

[@joseph78e4n6]

Very informative VIDEO .. incredible Presentation 👍

[@delinquenter]

If anything, these engines should be kept for the sake of it. I like 'em just the way, they are. Nothing can convince me otherwise.

[@JIm-w1b]

My dad who was in ww2 once told me, the big radials had a dynamic balancer that banged and klunked around, when the engine came to a stop and this was normal

[@UkrainianPaulie]

P-47. Hold my beer.

[@88SC]

Wright experimented with a 4090 cubic inch 22-cylinder radial, as well as Nakajima (Ha-51) from Japan. None of the Wright R-4090s exist, but the battered remnants of one of the Ha-51s still exists.

[@aircraftnut15]

Radial engines also require A LOT of oil to operate. They used oil for cooling and often had large oil tanks to allow the oil to cool before being pumped back into the engine.

[@A.X.76]

The Red Baron has entered the chat… “I love radial engines!”

[@donaldasayers]

The Vee engine might look more streamlined, but you still have to cool it, thus you must add the drag caused by the radiators.

[@ArneChristianRosenfeldt]

In theory diffusers transform velocity to pressure ( without much drag ). The slow velocity through the radiator has low drag. Then accelerate through a nozzle with this flaps like behind a radial or the F-22 Raptor. Flaps regulate the temperature. Ideal radiator fins have round leading edge .. a tube of coole coolant. Trailing edge needs to be a wedge. Contra-flow. At there radiators where the coolant flows cross, but goes through multiple tubes from back to front? Stagger those tubes like a two row radial. Theory also says that the exhaust velocity should be above plane velocity by means of a fan before the radiator. Like if the prop wash doesn’t hit the inlet.

[@Slaktrax]

A couple of points: Radials do not make better power than an inline engine. To make the equivalent power they needed to have a much larger capacity. Secondly, no radial engine can continue to run with a cylinder missing, the conrod and piston assembly would smash the crankcase to pieces within seconds. ...A cylinder head maybe. The most power a production R-4360 made was 4,300 hp but proved to be unreliable and needing intensive maintenance. Even the majority of later variants making 3,500 to 3,800 hp required a lot of maintenance and thus poor availability.

[@kenneth9874]

There's pictures of radials making it back to base with damaged cylinders

[@princesofthepower3690]

@@kenneth9874that’s different to missing cylinders. Also Radial installations are inherently less efficient at higher power loads due to the fact air is less efficient coolant medium than water.

[@kenneth9874]

@@princesofthepower3690 anytime there's a piece of a cylinder missing its not functioning, try running an inline with part of a cylinder missing.....good luck 😉

[@californiadreamin8423]

@@kenneth9874. I flew the DC3 in the early 80’s for 2 1/2 years. One night in the descent, the engine gave a slight cough, and though a sign of trouble , it kept running fine. As we taxied in, it sounded like a steam engine.. At first I could not see anything wrong when I inspected it. Then I realised the cowling was no longer round !! Then I noticed I could see behind the engine when looking at it. Then on close inspection I noticed the base of the cylinder was no longer attached to the crankcase, because all the studs had sheared !! It kept running though. 😊

[@thewatchman9540]

The R-4360 VDT (4,300 hp) was a highly unreliable engine due to the fact it had poor cooling characteristics more than anything! But you are right! Radials tend to have worse specific power output compared to Inline engines.

[@williamkerr3350]

Brilliant show mate,thanks.

[@willi-fg2dh]

and also too . . . the Wright R-975 Whirlwind powered the Sherman tank! . . . nine-cylinder air-cooled radial with a displacement of about 975 cu in and power ratings of 300-450 hp

[@jessefink2745]

You ought to do a video on uncommon cylinder layouts, such as the X cylinder layout. The Rolls Royce Vulture was an X-24.

[@florida995]

Interesting as I never thought about radial firing order but makes sense.

[@williamrobinson7435]

Interesting and nicely presented. Thanks for posting! 🌟👍

[@bicivelo]

Fantastic explanation! Great video. Thank you.

[@bobbressi5414]

This is a very informative video.

[@daveherbert6215]

Brilliant, just brilliant explanation 😊

[@superdivemaster]

Very comprehensive video ... Danke ...

[@jeffsaxton716]

The first air cooled ones cost a fortune, as the cylinders were milled from billets. The ultimate single engine was used on the Sopwith Camel which was very tricky to fly due to the gyroscopic effects of the spinning mass.

[@kenneth9874]

The Pratt and Whitney radials had milled cooling fins

[@carlkraus6034]

Radial engines are great and they are still in use. They haven't gone away yet.

[@mikearakelian6368]

On radials...big thing is to prevent hydronic lock...so must pull though by hand; or remove lower plugs to drain residual oil that collects in lower cylinders! So,longer preflight!! And make sure that others who fly ur plane do the same!

[@mikearakelian6368]

Also would like to restore one in my back yard; if I had one like to get hands dirty like working on old cars...

[@MrOlgrumpy]

Love the audio from radials

[@chrismoody1342]

The one thing I don’t understand the lubrication of a radial. Is the oil in the crankcase or remotely supplied. The oil has to collect some where, to be returned. With my limited understanding I would think that oil would collect at the bottom filling the backside of the pistons. The top cylinders would only get limited lubrication unless pumped to the wrist pins and con rods bearings. If somebody could explain for me. Like my comment so I can get a notification of a comment in response to my questions. Thx.

[@LetsGoAviate]

It uses a dry sump lubrication system. Oil is stored in an external tank and pumped to the engine via the passages under pressure, so lubrication of the top (or any) cylinders isn't a problem. Oil is returned to the oil tank via scavenge pumps located at the botrom of the crankcase. With the engine not running, oil does tend to collect in the bottom cylinders, causing hydrolock, and thus radial engines have a specific startup procedure to prevent damage.

[@robertmatch6550]

Very well done presentation. Thank you.

[@DavidFMayerPhD]

Truly excellent.

[@stevewheatley243]

Ive worked on engines of almost all types. Would love to get my hands on a radial and take it apart.