In 1964 I was in school for my A&P license, and our powerplant instructor was a WWII veteran mechanic. The man knew his engines and propellers better than anybody else, and he taught us well. However, when he told us about the Sabre engine we just looked at each other and wondered if he was joking with us. Actually, the engine was very real, and very important in the history of British fighter aircraft.The success of the Sabre convinced the Brits that the sleeve valve would eventually replace all poppet valve engines, but of course the jet engine ended the contest by the end of the war.
A good attempt by Napier at the time, but technology was already moving on to jets. Great overview of Brit fighter big engine development and sleeve valves.
It was Bristol that developed reliable sleeve valves. Napier had endless trouble trying to get them to work until the Air Ministry forced Bristol to release their technology for use by Napier.
Anybody who's a student of WW2 fighter development, knows about the Napier Sabre. I'm not conversant with it's history or its designer but I guess he must have been a brilliant engineer.
I was a student in the mid 1960s and we used have a session with an old fellow who used to discuss aspects of design. Turned out he was the chief test engineer at Napiers during WW2. When we returned after the Christmas break , a large crate had arrived that contained a Sabre engine. Under his supervision , we dismantled it. Every part was exquisitely engineered. The gears that were hand finished so that they meshed perfectly, the centrifuge to remove air bubbles from the lube oil, the list is endless.A truly master class in mechanical engineering.
@@DoktorBayerischeMotorenWerke Rejoice! AFAIK there are a few that should fly again quite soon, the Hawker Typhoon RB396 in UK, another Hawker Typhoon at the Canadian Aviation Heritage Centre of Montréal, and a Hawker Tempest V at Fantasy of Flight, FL, USA. And with bad luck accounted for, we should at least have one Sabre roaring again!
@@MC202zipper Yes, Fantasy of flight has two complete engines, one of them is a zero hours, new in crate. (if I remembered correctly Kermit doesn't have the correct propeller for either of them) Unfortunately, there are none of the old experts on these extremely complex engines left alive... so things will not be easy.
What a wonderful explanation of the operation of the Sabre engine ! As a an enthusiast of the Rocket-firing Typhoons that contributed so much to the after- D-day operations against the Panzers ( I remember watching newsreels showing the strafing of the convoys and ammunition trains) I really appreciated the clear explanation of a very complex engine. My favourite cousin worked for Napier after the war in the engineering department , so I have quite an interest in Napier engines.
Absolutely brilliant explanation of the mighty Sabre engine. It really was a work of engineering art to make all of those complex components work so seamlessly. By the end of the war it really was one of the great aero engines and made the Tempest V one of most formidable and greatest fighter bombers of that era.
The apparent complexity of the Sabre comes from the overall number of cylinders. When you consider the number of components per cylinder then the sleeve valve is far simpler. The prop shaft gearing with the helical cut drives helped immensely to reduce the torsion oscillations that play havoc with the wear and life time of the simpler single spur gear reduction used on the v12 engines. The twin drives to the supercharger also helped to isolate the high inertial load of the supercharger from the torsional variations of the engine and propellor. There is lot of smart engineering in the Sabre design.
I have had an early affinity with metal and engines since I was a kid. Starting at an early age with BSA motorcycles. I went on to join the RAF as a mechanic. I now run classic car's and have rebuilt a few. Now , having learned about the Napier, I'd love to get inside one.... Awesome pieces of kit...
Thanks ever so much for what I believe is the most easy to understand explanation of the operation of the Napier Sabre H-24 motor; just brilliant!! Going to geek out on the rest of your content now…😅
Great stuff! One of the unanticipated downsides of sodium filled valves, widely used by Lycoming, is moving the heat from the head to the stem tends to promote deposit buildup on the stem. Valve sticking from lead/carbon deposits on the stem/guide is a chronic problem on Lycomings.
@@kiwidiesel Yah, but that will extend landing distance. Makes a short field landing difficult. It needs to have a ground idle of 600 rpm or it will float down the runway quite a ways.
Thanks for this educational video. The description is not only basic but is detailed while remaining easy to understand! Perfect. I have always admired these engines and was lucky enough to see one at the Ottawa Aviation Museum.
Thanks for this. I work at a museum, Solent Sky in the UK, and we have one of these beautiful beasts. Next time I get asked some question about how they work I will give the visitor a link :)
Fasincating. Just subscribed. I understand the Napier somewhat, so I thought this video would be simplistic. It was anything but. You are comprehensive and clear. You mentioned that the heads allowed for a smaller cross section. To me, that would seem minimal, as the "junk" head needed to accept the reciprocating sleeve. Though the sleeve concept is straight forward, I've never been able to work out how oil gets to the head rings, or if trapped oil, which--at least in the Bristol--escapes through the venting valve, must be dealt with on each sleeve stroke. I have the feeling you know the answer 😉
One advantage of sleeve valves over poppet valves which was hinted at in this video, is that they run happily on lower octane fuel. One disadvantage that wasn't considered meaningful at the time, but which would make it near impossible to build one for automotive use today is that sleeve valve engines consume a lot of oil. Every time a sleeve port aligns with a cylinder port, it pushes a small quantity of the oil that lubricates the outside and th inside of the sleeve to either get blown into the cylinder if it's an intake port, or straight out the exhaust if it's an exhaust port.
thats a bit of a broad statement .. Bristol proved wrong with the Centaurus .. lowest bmsfc & hphr oil consumption of any aero engine .. 1st by a long way to reach 2000hrs tbo .. piston engine development in all fields stalled for a long time with the misconceptions of turbines & turbo compounding .. 20 years lost before the realisations of jet engine inefficiency & inflexibility of application .. Bristol developed highly effective sleeve valve port sealing before political influences from RR & govt development funding was diverted to jet engines
@@Errol.C-nz Aero engines consume a lot more oil on average than automotive engines, in particular modern ones. this American invention and technology were licensed to many European companies in particular British ones who developed them long after the Americans concluded it was an evolutionary dead-end concept, Britian lagged several years behind in internal combustion technology, their forte was always steam engines.
@@bocahdongo7769 No advantage spinning up to 20,000 on a propeller driven aircraft... 2,800 rpm is already too fast for a large diameter high efficiency prop..
@@DoktorBayerischeMotorenWerke just giving the example how far poppet valve already goes. Like let's be honest, nobody in mind thinking sleeve valve doing 20.000 RPM like what poppet valve did despite poppet valve being laughable 70 years before
Very good. Thanks. In my ignorance, I thought that the cylinders in the H engines were actually placed like an H. I didn't know that it was an H lying on its side.
LJK Setright was a staunch enthusiast for Napier engines, particularly the Sabre. He has also pointed out that the Sabre was the victim of politics - both governmental and inter-company. I believe that the problems with the early Sabres were mostly to do with its sleeve valves. I'm open to correction here, but I think that manufacturing these components to the required tolerances was not possible for Napier and that the UK government had to bring Bristol in as a subcontractor to do that job. I can no longer find a reference on YT, but I do remember reading a comment by Free French fighter ace, Pierre Clostermann to the effect that the Tempest was the best fighter he had experienced - mostly due to the power and response of its Napier Sabre engine.
Casting technology from Bristol solved it- centrifugal casting gave a cast cylinder with a consistent radial grain structure, so non-uniform distortion on heating was prevented. Napier's origin sleeves used standard static mould castings, whose distortions could cause seizure.
"The Big Show" (Le Grand Cirque) by P Clostermann is a gem of a book. And I used to read articles by LJK Setright in AUTOCAR magazine back in the 90's.
@@jc-d6179 I don't think it was casting technology alone, Bristol used a different material for the production sleeves after going through so many at enormous cost, the material (and yes casting technology) had to be considered for thermal expansion, strength, hardness, wear resistance, machinability, the list goes on. And then the machining itself was a major issue, the use of the centreless grinders imported from the USA and Bristol's serendipitous discovery of the final grind using worn grinding wheels to bring the sleeves into round within the tolerances - a story in itself. I can't remember how long they "aged" the sleeve castings before machining, but I can remember photos of them sitting in big piles still with casting cores inside out in the snow. Bristol had its own issues despite solving the sleeve issue, they had problems with heat ejection in the heads and numerous other issues. There are reasons the Centaurus was so late into production, technical reasons as well as "political" reasons and Roy Fedden's departure.
The second major issue was the hydrodynamic bearings used for the mains and big ends of the crankshafts. Vandervell built a factory across the road from Napier at Acton to work on the issues. Napier was not alone, when Mercedes switched from rollers to hydrodynamic bearings in their engines, it was not at all smooth sailing. This was greatly exacerbated by the single grade oils then in use. These oils caused serious starting issues on cold nights, when the Coffman starters didn't have enough power to start the engines, they used big heaters blowing hot air into the radiators to get the engines warm enough and also started them every few hours to keep them in readiness. The Coffman starter was not kind to the engine and caused its own problems.
That was a particularly clear, comprehensive explanation of the structure of the engine - truly excellent! With this in mind, would love to see your deep-dive of the RR Vulture engine (and why it failed), and also (although not directly aviation related) the Napier Deltic engine used on railway locos and British MTBs late in the war. Brilliant! Keep it up! 🤓👍
Thank you, That was excellent. I went to see the Typhoon restoration project in Sussex a few years ago and they had a hand cranked H24 engine to play with. Insanely complex. Thanks again.
Thank you Sir, a wonderful explanation and great footage of an extremely important engine design. You have a gift of clear and concise explanation ability!
My field is automotive, and the same scenario happened here. More cylinders and bigger bores made some engines humongous. Some are as large as a whole modern car. I love engines and have experience on Lycoming engines because they were used in Duesenberg cars. Other manufacturers also and the war was on in those days to be the most powerful and fastest. What's funny to me now is that we get more horsepower out of a 2 liter 4 cylinder than a V16 Lincoln or Caddy. It's been my pleasure to direct a car collection with cars and other vehicles going back to the beginning.
Well done, most videos on these high-powered WWII piston aircraft engines are full of errors, this video has what I believe to be one. There is no proof that the Sabre officially got to 3500hp. The last one, the VII, was type-rated at 3050hp for takeoff on ADI . Did they produce more than this? Probably, but this would have been more along the line of WEP, which I have never seen specified. I once believed the 3500hp figure, but after extensive searching, I have found no primary source to confirm this, so, for me, it is 3050hp One of the more interesting things about the sleeve valves used on the Sabre and Bristol engines was that the block had five ports but the sleeve only had four ports. This means that one port in the sleeve would alternatively pass cold inlet mixture followed by hot exhaust gases. This heat cycling is generally considered a bad idea, although I have never seen this issue explored in any detail. There is a great deal to cover in any complete story of the Sabre, unfortunately, much of the original Napier documentation has been lost. Many H pattern aircraft engine designs have been put forward, but the Sabre was the only one that made it to production. In the USA, both Continental and Pratt & Whitney worked on sleeve valve engines, P&W on the X1800 aka H2600 H24 for the army and the H3130 H24 for the Navy. These engines were considerably different to the Sabre and were closer to the layout of the Napier Dagger, albeit, with water cooling. Examples of these prototype engines still exist. The P&W effort came to an end after a change of management at P&W, P&W essentially bought their way out of the contract. Kimble D. McCutcheon's book "American Sleeve-Valve Aircraft Engines " has a wealth of information on the subject.
Thanks. I should perhaps have cited my sources for the 3,500hp claim (Oldmachinepress which I believe reputable, and some research papers with the same claim). There is even some sources claiming it achieved 4,000hp, but I did find counter-claims that there is no proof of that, so I reverted to the 3,500hp number. But I'm happy to concede if it was only 3,050hp, you may have researched that detail more extensively. I did consider including other H engines in the video but when I started digging deeper for research months ago I got very fascinated by the details of the the Sabre and so decided to focus on it. The Lycoming H-2470 may feature in a video soon though. I was in contact with Kimble some time ago but didn't realise he wrote the book about American sleeve valve engines. Thanks for the info.
According to LJK Setright in 'The Power to Fly'. the max power in service was 3750 hp., and it was tested at that power for 175 hours non-stop. The special engines built for the Heston racer gave 5,500 hp at 4200 rpm. on 45 lb boost.
@@PhilipSiddall Setright was miles off. First of all, the OP is likely right. I have also looked into this and could find no Sabre variant that ever actually ran at more than 3,050 hp, much less for 175 hrs continuously, much less in service. Part of the problem was the level of boost. Sleeve valve engines couldn't run the same levels of boost as poppet valve engines, simply because of thermal expansion. At high pressure the sleeves distort, particularly at the ports and create frictional losses and excessive heat. Remember that reciprocating engines run at approximately the same levels efficiency. The Rolls Royce Griffon was about the same capacity as the Sabre (36 litres) which developed about 2,400 hp in its most powerful variants. The idea that an engine of similar capacity and broadly similar design could produce as much as 5,500 hp seems a bit far fetched. There are only two ways to increase power: increase torque or increase revs. The most common way to increase torque was to increase boost which, as I've already said, had limited possibilities in the Sabre. As it was, the Sabre's normal max operating speed was 4,000 rpm. For more information on this, Calum Douglas has talked about it in some of his presentations and also in his book, _'The Secret Horsepower Race'._
@@LetsGoAviate I keep trying to post with some detail but it keeps getting deleted. So I will keep this short. If you go to the Old Machine Press article and scroll down to the comments, you will find some discussion on the power figures between Bill and myself where he cites which power figure is from what source. The 3055hp is flight-certified takeoff power, I have no information on WEP which may have been higher. It would be most unusual not to have a WEP power output. This, is of course the issue with just a single figure, a family of graphs is usually required to get the true story
Well presented! I learned a lot, especially on sleeve vales. I believe another advantage of the larger piston count and hence smaller bores is that the faster completion of the flame front across the smaller cylinder reduces tendency of pre-ignition (knock). I recall that from school in 1980. Regards.
The Sabre was quite innovative in some respects. It was oversquare, and a high rpm design with comparatively small cylinders. Had they instead gone with the tried and tested poppet valves, perhaps they'd had it in service years earlier.
@@jbepsilonif they’d used poppet valves the engine would have either been significantly underpowered or required boosting and had cooling problems. Poppet valve engines of the era produced significantly lower power per CC at the same boost levels.
@@robertpatrick3350Poppet valve aero engines of the era produced less power per volume because they were designs with big long stroked cylinders thus limiting maximum RPM. A Sabre like high rpm design could have been made with poppet valves as well.
Props to Charles Knight who invented the sleeve valve engine around the same time powered flight became a reality. His "Silent Knight" engine and the sleeve valve concept was licensed to many different automobile manufacturers before it found its way into aircraft engines. It just so happens my neighbor has a Tempest V under restoration and a couple of these Napier Sabre engines kicking around, so there is a chance we may yet hear one of these beasts run again in our lifetime. Personally, I think the advances made in metallurgy, machining, and lubrication since the Sabre's time in service would make it interesting.
Very, very good explanation of this complex engine, that was pretty extravagant for it's time. It didn't like running on low rpm or ideling, bacause spark plugs would get oily and with carbon deposits, and it woud start missfireing, so pilots were forced to rev the engine often while on the ground...
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Very interesting and a great review on old aero engines, the technology and engineering was very impressive. Thank you.
Thanks for your very interesting vid. In addition: in fysics kinetic energy = mass x speed square. In engine building this means energy = torque (mass) x revs (speed) square. Here we can clearly see that energy depends much more from revs (square!) than from torque. Almost strange that it took us so long to discover this.
As a lad I read all the books on WWII aircraft, and those that flew in them, I could find. When I began comparing performance stats the Tempest and Typhoon stood our and I delved deeper.. While absorbing information on the Sabre and its complexity a quote I'd read earlier about financing came to mind: Napier - mathematicion to the King. That explained it . . .
I was suprised to hear they had sodium filled valves in ww2. I am an automotive mechanic, some manufacturers in the last decade started offering sodium filled valve stems and touted it as state of the art tech...
Outstanding video presentation. Excellent animation and narration. My only observation for improvement is that correct English usage would be "number of cylinders", not "amount of cylinders". If you can count it discretely, it's 'number' and if you measure it in gross like water, it's 'amount'.
That was a fantastic video, I've been wanting a detailled breakdown of the Sabre for ages. The engine was dogged by technical issues due to its complexity at the start. Do you know what the issues were?
Mainly the sleeve's, which was sorted once Bristol agreed (not willingly) to assist Napier with this. Bristol has been making sleeve valves for some time by now and got all issues sorted out in peace time before the war. The issue I believe was out of roundness, meaning the sleeves wasn't perfectly circular on a very small scale, and the sleeves wore out prematurely. The other issue was the Coffman starter which damaged the sleeve drive componenets due to the sudden shock of the cartridge firing. And lastly (as far as I know) I carbon build-up also caused issues, sorted by some additive to the oil. All issues were sorted eventually making it more reliable that many would like to admit.
Wow!!! Incredibly complex and intense engineering!!! It makes one wnder why larger 2- Stroke engines were not produced.... One such design that had impressive Horse-power and Torque output was made by McCulloch Industries and produced well over 100 h.p. with tuned exhaust, naturally aspirated, aur cooled... It displace's 100 cu.in. ,weighs about 78 pounds, and they develop maximum torque at around 3,200 rpm and is an opposed -4 cylinder boxer type of an arrangement ... It has 2 ported rotary valve discs permantly cast onto the crankshaft that open's and close's the air/fuel paths going into the 2 sealed crankcases. Porting for exhaust and intake cycles are done by tranfer ports for intake air/fuel flow, and exhaust ports to scavenge the spent exahust out of the engine cylinders.,.These cylinder ports were cast into the cylinder walls... The movement of the pistons provided the precise timing required for opening & closing of the ports... A magneto fired each of the spark plugs with independant precision without the need for external electrical power... Perfect for light homebuilt aircraft projects... Light , powerful, simple, reliable... It is Called the McCulloch 4318 A and these engines were originally designed for drone target training aids, but later became very popular for homebuilt aircraft of various sorts especially gyro-copters...Today is: 11/07/24
Some cars had sleeve valve engines as well, the daimler double six was one. The sleeve valve engine was had considerably less mechanical noise making the cars very quite.
Thanks, there was no mention of Major Frank Halford who designed this engine, also designing the Gypsy engine series (long lived) and then the more powerful Halford H1 jet engine in 1942/43 that was the Goblin 3,500lb thrust engine to power the deH Vampire and then later the Ghost engine powering the DeH Venom!! A remarkable Mechanical engineer working for himself and Napier and later de Havilland. All his engines were long lived engines - good lubrication systems. It was only during the first 2 years of war use that the technicians had decided to alter the fuelling and firing timing, boost control (Factory settings) that detonation occurred destroying some engines and pilots were killed. Also of note, counting pistons, conrods, camshafts, crankshafts, valves, valve springs, sleeves that you find 173 components in a V12 Merlin versus 76 in the H24 Napier Sabre - which was the most complex ?
The Sleeve valve engine was designed and patented by American Charles Knight... Halfords achievements are generally overshadowed by Stanley Hooker and Adrian Lombard, the real genius behind Britain's jet program..
@@DoktorBayerischeMotorenWerke The de Havilland H1 (Goblin) was the first flight certified turbojet outside of Germany (assuming they flight-certified theirs). It also powered the Meteor on its maiden flight and was used to power the prototype Lockheed P-80 Shooting Star. His last turbojet before his premature death (1955) was the de Havilland Gyron (H4), an axial design and the most powerful turbojet of its time, designed specifically for supersonic flight. The 1957 Defence White Paper cancelled it and the aircraft it was designed to power. He also worked on rocket designs. If you want to pick someone at R-R (and yes Bristol) outside of Hooker in a design role rather than a management role, in my opinion, Geoff Wilde would be a better choice. For some reason (unknown) Stewart Tresilian refused to work under Lombard and resigned from R-R rather than do so. And again Knight's successful patent was for double-acting sleeve valves not single-acting, he lost the court case over patent infringement against Argyll for the Burt sleeve valve as his earlier patent for single-acting sleeve valves was found to be impractical. And of course, Halford still designed the Sabre and a number of other piston engines. If you want to break it down to giving Knight the credit, you may as well go the whole way and give the credit for designing all spark ignition ICEs up to current F1 engines to Nicolaus Otto.
@@robertnicholson7733 Actually that is incorrect, the Rolls-Royce Welland was the first British jet engine to achieve airworthiness certification. All German aircraft engines were required to pass RLM airworthiness certification standards before they were allowed to be adopted into Luftwaffe service. The exact same 100-hour PFTR test required by the RAF and the USAAF during WW2. Wilde was hired by Stanley and excelled under Stanley's tutelage Head of Rolls-Royce Aero Engine Baron Hives, said his best jet engineers were Stanley and Lombard and that his go to team was Elliott, Rubbra, Lovesey, Haworth and Davies when they were led by Stanley and Lombard Stanley and Lombard left Rolls-Royce to top positions at Bristol where they would go on to develop; The two greatest jet engines in British history, the _Olympus_ and the _Pegasus._ Charles Knight patented both types and he won his patent infringement suit, Argyl was bankrupted by the settlement. Yes, not to put too fine a point on it, but... Nicolaus Otto did in fact design the type of engines still used in Formula 1 today, the 4-cycle homogeneous charge combustion engine was invented by Otto and Langen. Any questions lad?
I've been an aircraft mechanic for 45 years and always considered myself as one "bad ass" A&P😅 I can hardly imagine what it might have been like working on this engine. The engineers and builders of this engine are indeed ..." bad ass." Considering the era, they are aviation LEGIONS!
Great video have always wanted to know how these awesome powerplants developed such large amounts of horsepower. Stories of early tempests tails and fuselage developing cracks and sometimes breaking off altogether made me interested in this huge engine . Read about vibration frequencies of this engine resonating and causing stress cracks that required some high level investergation to solve the issue.
The fuselage/tail problems of the Typhoon (I understand that the problem had been solved by the time the Tempest V came along) were due to a failure in the mass balance mechanism of the elevators, which caused tailplane flutter. Nothing to do with the engine. Hawkers had used a single, centrally-located mass-balance weight, operating through a system of levers; something in this mechanism suffered from metal fatigue. Later design standards require that the elevator and rudder mass-balance must be located near the tips of the surfaces, i.e. well away from the longitudinal axis of the aircraft.
While this is a fantastic story about this storied engine and a miracle of the pre-conventional computer age. There is much to be learned about all kinds of IC engines and their designs here. As they say in the business "BRILLIANT"!
The very first 'powered flight' was In 1852: Henri Giffard used a steam powered airship. The first powered flight of a heavier that air craft was in 1848. It was a steam powered lightweight model aeroplane designed by John Stringfellow, that was when the first powered flight of a heavier than air craft was made. 1903 was the date of the first successful flight of a man carrying powered aircraft!
The Brits produced 2 Major sleeve-valve engines during the War - the Sabre - by Napier, of course, and the Hercules - by Bristol. A RADIAL engine used in the Halifax and Beaufighter. Sleeve Valves have several advantages in engines - they are MUCH quieter, since they have NO valve noise (the Germans called the Beaufighter "Whispering Death" because it was much quieter than other twin-engine fighters) They can use lower octane fuel for the same compression ratio - or conversely - use much HIGHER Compression for the same octane fuel - giving them a MUCH higher power output for the same size engine and fuel quality. No Valve wear - They don't bang up and down, they just slide. They also have some DISadvantages - they are harder to machine - the sleeve has to be made to EXACT Tolerances, or it will jam - especially as engine temps go up and down. The block, sleeve and pistons all expand and contract at different rates. Because of this, they are prone to using a lot of oil.
I like the EGT approach - only valid for aero engines with no manifold- and definitely faster than taking out 48 spark plugs. But I suppose you'd hope to cut that to 24 suspect plugs by switching between mags. Even then, having worked in a V8 recently, with no load it'd be very difficult to discern a dropped cylinder out of 24 both on rpm or sound. Experience required!
@@daithiosioradain3380 Not true, I use EGT on all engine types to diagnose a misfire. Its easier now with laser thermometers. Polished chrome headers dont work though, diffracts the laser electronic engine diagnostic equipment existed at this time that could short-out a bank of cylinders or individual cylinders ignition leads to ground and the drop in rpm compared on a raster scale, albeit this method causes a much smaller rpm drop on a 24 cylinder engine that makes locating the cylinder harder to identify, it is easier with engines with fewer cylinders.
I recall as a teenager going to a scrap yard for spares for my car, seeing a vintage chassis with a sleeve valve engine, it had two cylinder blocks of three cylinders, one was missing. So sad that so much history was just thrown away.
While sleeve valves were certainly more efficient volumetrically, they were also extremely complex, and maintenance intensive, and their development took years to iron out for reliable production. It's pretty clear to see that the Sabres real super power was it's ability to rev 1,000 rpms higher than every other aircraft engine. The short stroke, and naturally balanced dual-boxer engine made far more power than similar or larger displacement aircraft engines from the ease with which it revved so much higher, more so than the more efficient airflow.
There is a very interesting video with Kermit Weeks and an english man who is specialized in restoring Napier's. He says that the war Sabres where like Bombs, they will go off Boom !!! It only being a matter of time. On the other hand the late Sabres (almost a new design) were very reliable and down rated ones were extensively used to power Train-Locomotives.
Would you consider looking into the acoustics of your studio? There is a fair amount of echo. No echo makes understanding your detailed explanation more pleasant. Thank you in advance.
The engineers that made this engine back then were geniuses and the metallurgy was way ahead of its time. Imagine if they used this tech for car engines, and kept improving where would we be now?
The American Knight Sleeve valve engine was first used in automobiles and later the technology was licensed to several British companies that developed them for aviation... improvements in poppet valve technology rendered them obsolete in cars in the 1930s.
Very interesting. It's nice to have a real person delivering the goods rather than an AI voice box with its exaggerated expression and mispronunciations bleating at you.
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In 1964 I was in school for my A&P license, and our powerplant instructor was a WWII veteran mechanic. The man knew his engines and propellers better than anybody else, and he taught us well. However, when he told us about the Sabre engine we just looked at each other and wondered if he was joking with us. Actually, the engine was very real, and very important in the history of British fighter aircraft.The success of the Sabre convinced the Brits that the sleeve valve would eventually replace all poppet valve engines, but of course the jet engine ended the contest by the end of the war.
A good attempt by Napier at the time, but technology was already moving on to jets.
Great overview of Brit fighter big engine development and sleeve valves.
It was Bristol that developed reliable sleeve valves. Napier had endless trouble trying to get them to work until the Air Ministry forced Bristol to release their technology for use by Napier.
Anybody who's a student of WW2 fighter development, knows about the Napier Sabre.
I'm not conversant with it's history or its designer but I guess he must have been a brilliant engineer.
The other advantage is better air flow
Into the cylinder since one of the biggest obstructions is the valve itself
Absolutely fascinating American technology.
This is probably the best technical and evidenced video on WW2 era engines on TH-cam. Excellent work!
Try Calum Douglas.
My exact thought too... a superb description of the engine and competing designs. Thank you.
Very well researched and narrated.
The Sabre often got labelled as unreliable but progress is always a rocky road.
In the end it came good thankfully.
Yes, a credit to himself and youtube
@@aerotube7291 Calum Douglas is much better than this. He’s an actual engine designer.
I was a student in the mid 1960s and we used have a session with an old fellow who used to discuss aspects of design. Turned out he was the chief test engineer at Napiers during WW2. When we returned after the Christmas break , a large crate had arrived that contained a Sabre engine. Under his supervision , we dismantled it. Every part was exquisitely engineered. The gears that were hand finished so that they meshed perfectly, the centrifuge to remove air bubbles from the lube oil, the list is endless.A truly master class in mechanical engineering.
That's must have been some experience! I can only imagine the excitement, today such an experience cannot be bought at virtually any price.
And that story is why there are no Sabre engines left running today... not a single one left in the world left in running condition..
Did you get to rebuild it?
@@DoktorBayerischeMotorenWerke Rejoice! AFAIK there are a few that should fly again quite soon, the Hawker Typhoon RB396 in UK, another Hawker Typhoon at the Canadian Aviation Heritage Centre of Montréal, and a Hawker Tempest V at Fantasy of Flight, FL, USA. And with bad luck accounted for, we should at least have one Sabre roaring again!
@@MC202zipper Yes, Fantasy of flight has two complete engines, one of them is a zero hours, new in crate. (if I remembered correctly Kermit doesn't have the correct propeller for either of them)
Unfortunately, there are none of the old experts on these extremely complex engines left alive... so things will not be easy.
This is probably the most straightforward and concise explanation of this aero engine to date . Very well done Sir .
What a wonderful explanation of the operation of the Sabre engine ! As a an enthusiast of the Rocket-firing Typhoons that contributed so much to the after- D-day operations against the Panzers ( I remember watching newsreels showing the strafing of the convoys and ammunition trains) I really appreciated the clear explanation of a very complex engine. My favourite cousin worked for Napier after the war in the engineering department , so I have quite an interest in Napier engines.
Absolutely brilliant explanation of the mighty Sabre engine. It really was a work of engineering art to make all of those complex components work so seamlessly. By the end of the war it really was one of the great aero engines and made the Tempest V one of most formidable and greatest fighter bombers of that era.
May I just say......... Holy hell! Wow! And the tempest is one of the coolest planes ever! Great video!
The apparent complexity of the Sabre comes from the overall number of cylinders. When you consider the number of components per cylinder then the sleeve valve is far simpler. The prop shaft gearing with the helical cut drives helped immensely to reduce the torsion oscillations that play havoc with the wear and life time of the simpler single spur gear reduction used on the v12 engines. The twin drives to the supercharger also helped to isolate the high inertial load of the supercharger from the torsional variations of the engine and propellor. There is lot of smart engineering in the Sabre design.
Great explanation and perfectly detailed explanation, thank you. I love big old piston engines and the prop theory too. I'm happy I subscribed 🙂
That's awesome, thanks.
I have had an early affinity with metal and engines since I was a kid.
Starting at an early age with BSA motorcycles.
I went on to join the RAF as a mechanic.
I now run classic car's and have rebuilt a few.
Now , having learned about the Napier, I'd love to get inside one....
Awesome pieces of kit...
Thanks ever so much for what I believe is the most easy to understand explanation of the operation of the Napier Sabre H-24 motor; just brilliant!!
Going to geek out on the rest of your content now…😅
Well made and informative
I liked the clarification of Boxer vs. Flat engine and the details on sleeved valves at the end
Well done!
Very informative video - thank you.
Great video. My father worked on this engine as a mechanic during the war. RCAF 438 Squadron
Well isn't this a weird coincidence... my grandfather was a pilot in the 438. I met one of the mechanics that he kept in touch with, Fred Berg.
Great stuff! One of the unanticipated downsides of sodium filled valves, widely used by Lycoming, is moving the heat from the head to the stem tends to promote deposit buildup on the stem. Valve sticking from lead/carbon deposits on the stem/guide is a chronic problem on Lycomings.
Marvel Mystery Oil in the crankcase
Having an engine minimum idle rpm of approximately 1200rpm negates most of the issues with buildup on valves etc. from lead deposits.
@@kiwidiesel
Yah, but that will extend landing distance. Makes a short field landing difficult. It needs to have a ground idle of 600 rpm or it will float down the runway quite a ways.
No valve stems on a Sabre- it's a sleeve valve engine!
@@PhilipSiddall
Yes. So is a Bristol Centaurus. We were digressing into Lycomings...
Thanks for this educational video. The description is not only basic but is detailed while remaining easy to understand! Perfect. I have always admired these engines and was lucky enough to see one at the Ottawa Aviation Museum.
Brilliant masterclass in this engine’s unique design.
Fascinating comparison and well narrated.
Fascinating and expertly delivered. Thanks!
Thanks for this. I work at a museum, Solent Sky in the UK, and we have one of these beautiful beasts. Next time I get asked some question about how they work I will give the visitor a link :)
Great video, a fine study on this interesting engine.
Wow, I just learned a lot! I thought I knew a fair bit about the Sabre. How wrong I was! Thank you for an excellent video.
Fasincating. Just subscribed. I understand the Napier somewhat, so I thought this video would be simplistic. It was anything but. You are comprehensive and clear. You mentioned that the heads allowed for a smaller cross section. To me, that would seem minimal, as the "junk" head needed to accept the reciprocating sleeve. Though the sleeve concept is straight forward, I've never been able to work out how oil gets to the head rings, or if trapped oil, which--at least in the Bristol--escapes through the venting valve, must be dealt with on each sleeve stroke. I have the feeling you know the answer 😉
What a wonderfully informative video very well presented and full of interesting stuff, well done !
One advantage of sleeve valves over poppet valves which was hinted at in this video, is that they run happily on lower octane fuel. One disadvantage that wasn't considered meaningful at the time, but which would make it near impossible to build one for automotive use today is that sleeve valve engines consume a lot of oil. Every time a sleeve port aligns with a cylinder port, it pushes a small quantity of the oil that lubricates the outside and th inside of the sleeve to either get blown into the cylinder if it's an intake port, or straight out the exhaust if it's an exhaust port.
thats a bit of a broad statement .. Bristol proved wrong with the Centaurus .. lowest bmsfc & hphr oil consumption of any aero engine .. 1st by a long way to reach 2000hrs tbo .. piston engine development in all fields stalled for a long time with the misconceptions of turbines & turbo compounding .. 20 years lost before the realisations of jet engine inefficiency & inflexibility of application .. Bristol developed highly effective sleeve valve port sealing before political influences from RR & govt development funding was diverted to jet engines
@@Errol.C-nz Aero engines consume a lot more oil on average than automotive engines, in particular modern ones.
this American invention and technology were licensed to many European companies in particular British ones who developed them long after the Americans concluded it was an evolutionary dead-end concept, Britian lagged several years behind in internal combustion technology, their forte was always steam engines.
@@Errol.C-nzon aero engine at that time.
We already have 20.000 RPM NA poppet valve engine. If we forget 😊
@@bocahdongo7769 No advantage spinning up to 20,000 on a propeller driven aircraft... 2,800 rpm is already too fast for a large diameter high efficiency prop..
@@DoktorBayerischeMotorenWerke just giving the example how far poppet valve already goes.
Like let's be honest, nobody in mind thinking sleeve valve doing 20.000 RPM like what poppet valve did despite poppet valve being laughable 70 years before
Brilliant! Every aspect covered and absolutely correct. Many thanks. Liked and subscribed.
Very good. Thanks. In my ignorance, I thought that the cylinders in the H engines were actually placed like an H. I didn't know that it was an H lying on its side.
Yeah they turned the Sabre on it's side but the Napier Rapier and Dagger engines that preceded the Sabre was upright like an "H".
@@LetsGoAviate I assumed it was like a P&W X-1800.
Absolutely excellent video! Perfect explanation and presentation. Thank you so much for sharing!
This is what TH-cam should be!
Brilliant video - excellent animated drawings, and subject detail. Thanks for posting it!
LJK Setright was a staunch enthusiast for Napier engines, particularly the Sabre. He has also pointed out that the Sabre was the victim of politics - both governmental and inter-company. I believe that the problems with the early Sabres were mostly to do with its sleeve valves. I'm open to correction here, but I think that manufacturing these components to the required tolerances was not possible for Napier and that the UK government had to bring Bristol in as a subcontractor to do that job.
I can no longer find a reference on YT, but I do remember reading a comment by Free French fighter ace, Pierre Clostermann to the effect that the Tempest was the best fighter he had experienced - mostly due to the power and response of its Napier Sabre engine.
Casting technology from Bristol solved it- centrifugal casting gave a cast cylinder with a consistent radial grain structure, so non-uniform distortion on heating was prevented. Napier's origin sleeves used standard static mould castings, whose distortions could cause seizure.
Well I'm glad he Setright the info for this engine
"The Big Show" (Le Grand Cirque) by P Clostermann is a gem of a book. And I used to read articles by LJK Setright in AUTOCAR magazine back in the 90's.
@@jc-d6179 I don't think it was casting technology alone, Bristol used a different material for the production sleeves after going through so many at enormous cost, the material (and yes casting technology) had to be considered for thermal expansion, strength, hardness, wear resistance, machinability, the list goes on. And then the machining itself was a major issue, the use of the centreless grinders imported from the USA and Bristol's serendipitous discovery of the final grind using worn grinding wheels to bring the sleeves into round within the tolerances - a story in itself.
I can't remember how long they "aged" the sleeve castings before machining, but I can remember photos of them sitting in big piles still with casting cores inside out in the snow.
Bristol had its own issues despite solving the sleeve issue, they had problems with heat ejection in the heads and numerous other issues. There are reasons the Centaurus was so late into production, technical reasons as well as "political" reasons and Roy Fedden's departure.
The second major issue was the hydrodynamic bearings used for the mains and big ends of the crankshafts. Vandervell built a factory across the road from Napier at Acton to work on the issues. Napier was not alone, when Mercedes switched from rollers to hydrodynamic bearings in their engines, it was not at all smooth sailing. This was greatly exacerbated by the single grade oils then in use. These oils caused serious starting issues on cold nights, when the Coffman starters didn't have enough power to start the engines, they used big heaters blowing hot air into the radiators to get the engines warm enough and also started them every few hours to keep them in readiness. The Coffman starter was not kind to the engine and caused its own problems.
That was a particularly clear, comprehensive explanation of the structure of the engine - truly excellent!
With this in mind, would love to see your deep-dive of the RR Vulture engine (and why it failed), and also (although not directly aviation related) the Napier Deltic engine used on railway locos and British MTBs late in the war.
Brilliant! Keep it up! 🤓👍
The Deltic certainly is aviation related, Napier purchased the design from Jumo (Jumo 218) and it was originally intended as a Diesel aero-engine.
Thank you, That was excellent.
I went to see the Typhoon restoration project in Sussex a few years ago and they had a hand cranked H24 engine to play with. Insanely complex. Thanks again.
This is one of my favorite engines! Thanks a lot for the video and for all the details, stats and info 👍👍
Great video. It was simple to follow, and provided enough explanation for a beginner. I enjoyed it quite a lot.
Glad to hear that, thanks for letting me know.
Thank you Sir, a wonderful explanation and great footage of an extremely important engine design.
You have a gift of clear and concise explanation ability!
Excellent video - congrats!! This channel and Driving 4 Answers set a very high bar for ICE engineering videos.
Thaaaaaank you for including the firing order. Diagrams for flat-12s are mysteriously hard to find.
Bloody hell, that was exceptionally clear. Good job.
My field is automotive, and the same scenario happened here. More cylinders and bigger bores made some engines humongous. Some are as large as a whole modern car. I love engines and have experience on Lycoming engines because they were used in Duesenberg cars. Other manufacturers also and the war was on in those days to be the most powerful and fastest. What's funny to me now is that we get more horsepower out of a 2 liter 4 cylinder than a V16 Lincoln or Caddy. It's been my pleasure to direct a car collection with cars and other vehicles going back to the beginning.
Well done, most videos on these high-powered WWII piston aircraft engines are full of errors, this video has what I believe to be one. There is no proof that the Sabre officially got to 3500hp. The last one, the VII, was type-rated at 3050hp for takeoff on ADI . Did they produce more than this? Probably, but this would have been more along the line of WEP, which I have never seen specified. I once believed the 3500hp figure, but after extensive searching, I have found no primary source to confirm this, so, for me, it is 3050hp
One of the more interesting things about the sleeve valves used on the Sabre and Bristol engines was that the block had five ports but the sleeve only had four ports. This means that one port in the sleeve would alternatively pass cold inlet mixture followed by hot exhaust gases. This heat cycling is generally considered a bad idea, although I have never seen this issue explored in any detail.
There is a great deal to cover in any complete story of the Sabre, unfortunately, much of the original Napier documentation has been lost.
Many H pattern aircraft engine designs have been put forward, but the Sabre was the only one that made it to production.
In the USA, both Continental and Pratt & Whitney worked on sleeve valve engines, P&W on the X1800 aka H2600 H24 for the army and the H3130 H24 for the Navy. These engines were considerably different to the Sabre and were closer to the layout of the Napier Dagger, albeit, with water cooling. Examples of these prototype engines still exist. The P&W effort came to an end after a change of management at P&W, P&W essentially bought their way out of the contract. Kimble D. McCutcheon's book "American Sleeve-Valve Aircraft Engines " has a wealth of information on the subject.
Thanks. I should perhaps have cited my sources for the 3,500hp claim (Oldmachinepress which I believe reputable, and some research papers with the same claim). There is even some sources claiming it achieved 4,000hp, but I did find counter-claims that there is no proof of that, so I reverted to the 3,500hp number.
But I'm happy to concede if it was only 3,050hp, you may have researched that detail more extensively.
I did consider including other H engines in the video but when I started digging deeper for research months ago I got very fascinated by the details of the the Sabre and so decided to focus on it. The Lycoming H-2470 may feature in a video soon though.
I was in contact with Kimble some time ago but didn't realise he wrote the book about American sleeve valve engines.
Thanks for the info.
According to LJK Setright in 'The Power to Fly'. the max power in service was 3750 hp., and it was tested at that power for 175 hours non-stop. The special engines built for the Heston racer gave 5,500 hp at 4200 rpm. on 45 lb boost.
@@PhilipSiddall Setright was miles off. First of all, the OP is likely right. I have also looked into this and could find no Sabre variant that ever actually ran at more than 3,050 hp, much less for 175 hrs continuously, much less in service.
Part of the problem was the level of boost. Sleeve valve engines couldn't run the same levels of boost as poppet valve engines, simply because of thermal expansion. At high pressure the sleeves distort, particularly at the ports and create frictional losses and excessive heat.
Remember that reciprocating engines run at approximately the same levels efficiency. The Rolls Royce Griffon was about the same capacity as the Sabre (36 litres) which developed about 2,400 hp in its most powerful variants. The idea that an engine of similar capacity and broadly similar design could produce as much as 5,500 hp seems a bit far fetched.
There are only two ways to increase power: increase torque or increase revs. The most common way to increase torque was to increase boost which, as I've already said, had limited possibilities in the Sabre. As it was, the Sabre's normal max operating speed was 4,000 rpm.
For more information on this, Calum Douglas has talked about it in some of his presentations and also in his book, _'The Secret Horsepower Race'._
@@LetsGoAviatePierre Clostermann said the engine of his Tempest “Le Grand Charles” was tuned to 3,500 hp for “Diver” missions, intercepting V1s.
@@LetsGoAviate I keep trying to post with some detail but it keeps getting deleted. So I will keep this short. If you go to the Old Machine Press article and scroll down to the comments, you will find some discussion on the power figures between Bill and myself where he cites which power figure is from what source.
The 3055hp is flight-certified takeoff power, I have no information on WEP which may have been higher. It would be most unusual not to have a WEP power output.
This, is of course the issue with just a single figure, a family of graphs is usually required to get the true story
My father was a master machinist who made torpedo gears among other things. He would have loved this engine. Thanks for the excellent video.
Thanks, I learned a lot and you explained the differences very well. I am now a subscriber and I'm looking forward to checking out your other videos.
Well presented! I learned a lot, especially on sleeve vales. I believe another advantage of the larger piston count and hence smaller bores is that the faster completion of the flame front across the smaller cylinder reduces tendency of pre-ignition (knock). I recall that from school in 1980.
Regards.
The Sabre was quite innovative in some respects. It was oversquare, and a high rpm design with comparatively small cylinders.
Had they instead gone with the tried and tested poppet valves, perhaps they'd had it in service years earlier.
@@jbepsilonif they’d used poppet valves the engine would have either been significantly underpowered or required boosting and had cooling problems. Poppet valve engines of the era produced significantly lower power per CC at the same boost levels.
@@robertpatrick3350Poppet valve aero engines of the era produced less power per volume because they were designs with big long stroked cylinders thus limiting maximum RPM. A Sabre like high rpm design could have been made with poppet valves as well.
Really enjoyed that....a clear insightful explanation....
Brilliant discussion - I learned a lot. Thank you!
Props to Charles Knight who invented the sleeve valve engine around the same time powered flight became a reality. His "Silent Knight" engine and the sleeve valve concept was licensed to many different automobile manufacturers before it found its way into aircraft engines. It just so happens my neighbor has a Tempest V under restoration and a couple of these Napier Sabre engines kicking around, so there is a chance we may yet hear one of these beasts run again in our lifetime. Personally, I think the advances made in metallurgy, machining, and lubrication since the Sabre's time in service would make it interesting.
Indeed, its an absolutely fascinating American technology that was licensed to several European manufacturers including some in Britain..
Very, very good explanation of this complex engine, that was pretty extravagant for it's time. It didn't like running on low rpm or ideling, bacause spark plugs would get oily and with carbon deposits, and it woud start missfireing, so pilots were forced to rev the engine often while on the ground...
Very interesting and a great review on old aero engines, the technology and engineering was very impressive. Thank you.
Thanks for your very interesting vid. In addition: in fysics kinetic energy = mass x speed square. In engine building this means energy = torque (mass) x revs (speed) square. Here we can clearly see that energy depends much more from revs (square!) than from torque. Almost strange that it took us so long to discover this.
Top notch explanation and very well described. Keep it up👍👍
As a lad I read all the books on WWII aircraft, and those that flew in them, I could find. When I began comparing performance stats the Tempest and Typhoon stood our and I delved deeper..
While absorbing information on the Sabre and its complexity a quote I'd read earlier about financing came to mind: Napier - mathematicion to the King. That explained it . . .
Really hoping you make a series out of this going through different engines for the various nations.
I love making these videos, so I will definitely make more. I'm already busy with the next one 🙂
thanks for the clear explanation and clear graphics.
Well done presentation. Mike Patey's 'Scrappy' sighting at 18:11. 🙂
Great vid, well explained and demonstrated, thanks. Subscribed.
I'd be fascinated to see your take on the Rolls Royce Crecy.
I was suprised to hear they had sodium filled valves in ww2.
I am an automotive mechanic, some manufacturers in the last decade started offering sodium filled valve stems and touted it as state of the art tech...
Excellent presentation
Outstanding video presentation. Excellent animation and narration. My only observation for improvement is that correct English usage would be "number of cylinders", not "amount of cylinders". If you can count it discretely, it's 'number' and if you measure it in gross like water, it's 'amount'.
Boy that is ONE beautifull engine and piece of enginering.
Another fascinating video. Thank you!
This video is mind blowing!! Fantastic job!
That was a fantastic video, I've been wanting a detailled breakdown of the Sabre for ages. The engine was dogged by technical issues due to its complexity at the start. Do you know what the issues were?
Mainly the sleeve's, which was sorted once Bristol agreed (not willingly) to assist Napier with this. Bristol has been making sleeve valves for some time by now and got all issues sorted out in peace time before the war. The issue I believe was out of roundness, meaning the sleeves wasn't perfectly circular on a very small scale, and the sleeves wore out prematurely.
The other issue was the Coffman starter which damaged the sleeve drive componenets due to the sudden shock of the cartridge firing.
And lastly (as far as I know) I carbon build-up also caused issues, sorted by some additive to the oil.
All issues were sorted eventually making it more reliable that many would like to admit.
The main issue was sleeve seizures, eventually solved when Bristol were involved and made the sleeves for Napier.
Great video. I love engines. Have rebuilt many a motorcycle emgine, but this was great
WW2 Aero V-12 Design Decisions Explained : th-cam.com/video/Tz8vTnl-pAU/w-d-xo.html
V8 Aero Engines Explained : th-cam.com/video/wIKkp5Qd02o/w-d-xo.html
Inline 6 Aero Engine Explained : th-cam.com/video/Su9WN0Pi04s/w-d-xo.html
Wow!!! Incredibly complex and intense engineering!!! It makes one wnder why larger 2- Stroke engines were not produced....
One such design that had impressive Horse-power and Torque output was made by McCulloch Industries and produced well over 100 h.p. with tuned exhaust, naturally aspirated, aur cooled... It displace's 100 cu.in. ,weighs about 78 pounds, and they develop maximum torque at around 3,200 rpm and is an opposed -4 cylinder boxer type of an arrangement ... It has 2 ported rotary valve discs permantly cast onto the crankshaft that open's and close's the air/fuel paths going into the 2 sealed crankcases.
Porting for exhaust and intake cycles are done by tranfer ports for intake air/fuel flow, and exhaust ports to scavenge the spent exahust out of the engine cylinders.,.These cylinder ports were cast into the cylinder walls... The movement of the pistons provided the precise timing required for opening & closing of the ports... A magneto fired each of the spark plugs with independant precision without the need for external electrical power... Perfect for light homebuilt aircraft projects... Light , powerful, simple, reliable... It is Called the McCulloch 4318 A and these engines were originally designed for drone target training aids, but later became very popular for homebuilt aircraft of various sorts especially gyro-copters...Today is: 11/07/24
Some cars had sleeve valve engines as well, the daimler double six was one. The sleeve valve engine was had considerably less mechanical noise making the cars very quite.
Yes, it is an American invention and technology by Charles Knight, it was licensed to several European manufacturers... in particular British ones.
Excellent review of an engine I was not familiar with. Thx.
Thanks, there was no mention of Major Frank Halford who designed this engine, also designing the Gypsy engine series (long lived) and then the more powerful Halford H1 jet engine in 1942/43 that was the Goblin 3,500lb thrust engine to power the deH Vampire and then later the Ghost engine powering the DeH Venom!! A remarkable Mechanical engineer working for himself and Napier and later de Havilland. All his engines were long lived engines - good lubrication systems. It was only during the first 2 years of war use that the technicians had decided to alter the fuelling and firing timing, boost control (Factory settings) that detonation occurred destroying some engines and pilots were killed.
Also of note, counting pistons, conrods, camshafts, crankshafts, valves, valve springs, sleeves that you find 173 components in a V12 Merlin versus 76 in the H24 Napier Sabre - which was the most complex ?
The Sleeve valve engine was designed and patented by American Charles Knight... Halfords achievements are generally overshadowed by Stanley Hooker and Adrian Lombard, the real genius behind Britain's jet program..
@@DoktorBayerischeMotorenWerke
The de Havilland H1 (Goblin) was the first flight certified turbojet outside of Germany (assuming they flight-certified theirs). It also powered the Meteor on its maiden flight and was used to power the prototype Lockheed P-80 Shooting Star.
His last turbojet before his premature death (1955) was the
de Havilland Gyron (H4), an axial design and the most powerful turbojet of its time, designed specifically for supersonic flight. The 1957 Defence White Paper cancelled it and the aircraft it was designed to power.
He also worked on rocket designs.
If you want to pick someone at R-R (and yes Bristol) outside of Hooker in a design role rather than a management role, in my opinion, Geoff Wilde would be a better choice. For some reason (unknown) Stewart Tresilian refused to work under Lombard and resigned from R-R rather than do so.
And again Knight's successful patent was for double-acting sleeve valves not single-acting, he lost the court case over patent infringement against Argyll for the Burt sleeve valve as his earlier patent for single-acting sleeve valves was found to be impractical.
And of course, Halford still designed the Sabre and a number of other piston engines. If you want to break it down to giving Knight the credit, you may as well go the whole way and give the credit for designing all spark ignition ICEs up to current F1 engines to Nicolaus Otto.
@@robertnicholson7733 Actually that is incorrect, the Rolls-Royce Welland was the first British jet engine to achieve airworthiness certification.
All German aircraft engines were required to pass RLM airworthiness certification standards before they were allowed to be adopted into Luftwaffe service.
The exact same 100-hour PFTR test required by the RAF and the USAAF during WW2.
Wilde was hired by Stanley and excelled under Stanley's tutelage
Head of Rolls-Royce Aero Engine
Baron Hives, said his best jet engineers were Stanley and Lombard and that his go to team was Elliott, Rubbra, Lovesey, Haworth and Davies when they were led by Stanley and Lombard
Stanley and Lombard left Rolls-Royce to top positions at Bristol where they would go on to develop;
The two greatest jet engines in British history, the _Olympus_ and the _Pegasus._
Charles Knight patented both types and he won his patent infringement suit, Argyl was bankrupted by the settlement.
Yes, not to put too fine a point on it, but... Nicolaus Otto did in fact design the type of engines still used in Formula 1 today, the 4-cycle homogeneous charge combustion engine was invented by Otto and Langen.
Any questions lad?
I've been an aircraft mechanic for 45 years and always considered myself as one "bad ass" A&P😅 I can hardly imagine what it might have been like working on this engine. The engineers and builders of this engine are indeed ..." bad ass." Considering the era, they are aviation LEGIONS!
Excellent presentation! ❤
Great video have always wanted to know how these awesome powerplants developed such large amounts of horsepower. Stories of early tempests tails and fuselage developing cracks and sometimes breaking off altogether made me interested in this huge engine . Read about vibration frequencies of this engine resonating and causing stress cracks that required some high level investergation to solve the issue.
The fuselage/tail problems of the Typhoon (I understand that the problem had been solved by the time the Tempest V came along) were due to a failure in the mass balance mechanism of the elevators, which caused tailplane flutter. Nothing to do with the engine. Hawkers had used a single, centrally-located mass-balance weight, operating through a system of levers; something in this mechanism suffered from metal fatigue. Later design standards require that the elevator and rudder mass-balance must be located near the tips of the surfaces, i.e. well away from the longitudinal axis of the aircraft.
Cheers Sir, although you bent my brain, I could understand your very clear presentation.
While this is a fantastic story about this storied engine and a miracle of the pre-conventional computer age. There is much to be learned about all kinds of IC engines and their designs here. As they say in the business "BRILLIANT"!
Wow! Great Video!
The very first 'powered flight' was In 1852: Henri Giffard used a steam powered airship. The first powered flight of a heavier that air craft was in 1848. It was a steam powered lightweight model aeroplane designed by John Stringfellow, that was when the first powered flight of a heavier than air craft was made. 1903 was the date of the first successful flight of a man carrying powered aircraft!
The photo of a plane carrying a person should clear up that confusion 🙂
The Brits produced 2 Major sleeve-valve engines during the War - the Sabre - by Napier, of course, and the Hercules - by Bristol. A RADIAL engine used in the Halifax and Beaufighter.
Sleeve Valves have several advantages in engines - they are MUCH quieter, since they have NO valve noise (the Germans called the Beaufighter "Whispering Death" because it was much quieter than other twin-engine fighters)
They can use lower octane fuel for the same compression ratio - or conversely - use much HIGHER Compression for the same octane fuel - giving them a MUCH higher power output for the same size engine and fuel quality.
No Valve wear - They don't bang up and down, they just slide.
They also have some DISadvantages - they are harder to machine - the sleeve has to be made to EXACT Tolerances, or it will jam - especially as engine temps go up and down. The block, sleeve and pistons all expand and contract at different rates. Because of this, they are prone to using a lot of oil.
And the Bristol Centaurus
@@robertpatrick3350 Forgot that till after I'd posted it....
‘Whispering death’, like ‘the forked tailed devil’, is likely a myth.
Absolutely fascinating American technology.
@@DoktorBayerischeMotorenWerke Sorry - that's BRITISH Technology.
Good episode
Imagine trying to trace a misfire on this beast!!! Excellent presentation.
EGT probes. or spark drop test.
I like the EGT approach - only valid for aero engines with no manifold- and definitely faster than taking out 48 spark plugs. But I suppose you'd hope to cut that to 24 suspect plugs by switching between mags. Even then, having worked in a V8 recently, with no load it'd be very difficult to discern a dropped cylinder out of 24 both on rpm or sound. Experience required!
@@daithiosioradain3380 Not true, I use EGT on all engine types to diagnose a misfire. Its easier now with laser thermometers. Polished chrome headers dont work though, diffracts the laser
electronic engine diagnostic equipment existed at this time that could short-out a bank of cylinders or individual cylinders ignition leads to ground and the drop in rpm compared on a raster scale,
albeit this method causes a much smaller rpm drop on a 24 cylinder engine that makes locating the cylinder harder to identify, it is easier with engines with fewer cylinders.
I recall as a teenager going to a scrap yard for spares for my car, seeing a vintage chassis with a sleeve valve engine, it had two cylinder blocks of three cylinders, one was missing. So sad that so much history was just thrown away.
very interesting !! good work.. beautiful
Very thorough. Thanks.
While sleeve valves were certainly more efficient volumetrically, they were also extremely complex, and maintenance intensive, and their development took years to iron out for reliable production. It's pretty clear to see that the Sabres real super power was it's ability to rev 1,000 rpms higher than every other aircraft engine. The short stroke, and naturally balanced dual-boxer engine made far more power than similar or larger displacement aircraft engines from the ease with which it revved so much higher, more so than the more efficient airflow.
There is a very interesting video with Kermit Weeks and an english man who is specialized in restoring Napier's. He says that the war Sabres where like Bombs, they will go off Boom !!! It only being a matter of time. On the other hand the late Sabres (almost a new design) were very reliable and down rated ones were extensively used to power Train-Locomotives.
Great video! Thank you
12:53 this animation explains everything!
Brilliant video. Thank you.
Would you consider looking into the acoustics of your studio? There is a fair amount of echo. No echo makes understanding your detailed explanation more pleasant. Thank you in advance.
Great information thank you will you be doing how sleeves work 👍👍🇦🇺
Sodium filled exhaust valves existed since the '20s (and the research on them begun during WWI ). They made the sleeves valve obsolete.
The engineers that made this engine back then were geniuses and the metallurgy was way ahead of its time. Imagine if they used this tech for car engines, and kept improving where would we be now?
The American Knight Sleeve valve engine was first used in automobiles and later the technology was licensed to several British companies that developed them for aviation... improvements in poppet valve technology rendered them obsolete in cars in the 1930s.
Well you totally nailed it for me.
Smithsonian magazine had a great issue on big engines (back when it was good). That exact H 24 was featured among others.
That was fantastic. Thank you. ❤
Questions ?
How was the sleeve valve sealed against the cylinder and the cylinder bore?
Was there a lot of blow by, with a supercharger?
Sealing was accomplished via oil. This resulted in very high oil consumption.
That was fabulous
Very interesting. It's nice to have a real person delivering the goods rather than an AI voice box with its exaggerated expression and mispronunciations bleating at you.
Great video thank you.
Top vlog! Just top!
Wowow cool. Learning is fun!