I was a member of an Air Guard unit that had C-121C Constellations for several years. Flying on one of those beauties at night I liked to sit by a window and watch the exhaust flames. I marveled at those turbines and wondered how they stayed together when the entire exhaust, flight hood (turbine cover) were orange hot while blue flame streamed from the exhaust. Fascinating.
Wow, awesome story. Thank you for sharing. Im a bit envious as Ill not get a chance to fly on a Connie, closest I ever get was flying the Orion. Anyway, thank you for your service, and for sharing your experience.
@@mikesmith7249 DC-7 Co-pilot here.got to make a night takeoff in a DC-7 with a load of 115/145 that we picked up in Reno/Stead. An F-15 in full burner had nothing on it.
I have such a turbine wheel at home. It serves as a foot for a desk lamp, it is really heavy. Hard to believe that those tiny blades make 150HP per turbine. The lamp is the reading lamp from the navigators desk of a Super Connie. 😃
In this computerized world it always impresses me that these enormously complex machines were designed using pencils and paper. In those days the designers had to visualize the third dimension.
Just found this I was a Copilot on DC-7s for an Airtanker outfit. Did that for 10 years. Much respect for the 3350 running them was as much art as science.
When I was in A&P school in the mid 90's we came onto these in one of my engine classes. One of the instructors started out in the mid 50's with the USAF and was pretty familiar with these as well as the 4360 in the B 36, which he crewed on for a while. Looking at the design I asked what it was worth considering the added weight and complexity, and he said almost 200 HP extra each. Knowing these were on the Connies airlines were flying, an extra 500 HP or so was a big advantage and let the airlines justify keeping those planes as long as it took for commercial jet aircraft to be worth the investment. That instructor had some fun stories about the B 36, like how when it took off each engine had a 100 gallon oil tank and each wing carried another 300 gallons of oil for topping off, when one landed there was little to no oil left, and that when parked under each engine they had a trailer with oil catch pans feeding into a tank. He said cylinders blowing off wasn't unusual, and they were a ton of hard work to keep flying. Large radials sound like a massive expensive pain, and it's little wonder, that like the horse when the early automobiles appeared, they were quickly gotten away from as soon as it was practical.
Fantastic story, thanks for sharing. I didnt know the B-36 was equipped with fuselage mounted oil tanks but it makes sense. I know that the C-54 and C-118 both had them. I imagine because engine oil was the limiting factor, not crew rest or fuel capacity. I wonder then about the NB-36H..
I'm sure that's correct. I used to work with a man who was a mechanic working on B17's in England during WW2. He told me that each engine had a nacelle mounted 37 gallon oil tank, and that those engines, even when new, would burn an easy gallon, sometime 2, per hour. Just the nature of radials I guess.
@@6h471 The DC-6 has 40 gallon oil tanks per engine, after a good days worth of flying, you'll probably put between 5 and 12 gallons of oil in each tank.
I flew DC-7s in the early 80s as air tankers, they had the 3350s with PRTs. 3400 HP for takeoff, either 2800 or 2900 continuous (can't remember.......lol) with 115/145 (purple gas), a bit less with 100/130 (green gas). The key to keeping the engine in one piece was to watch the temps closely and go easy on power changes. The other thing to watch was BMEP (Brake Mean Effective Pressure). If one cylinder goes low, there's a good chance that its exhaust valve is burning. I only flew in hot weather (fire season) and with 115/145, the takeoff manifold pressure was in the high 50s. With 100/130, it was low 50s. One thing I learned early on was if you mention PRTs to an A&P, you'll learn a whole new set of cusswords.........lol. The 3350 is a pretty amazing engine considering it first ran in 1937, back then there wasn't any sort of computer drafting or even calculators. If close was good enough, you used a slide rule, if it needed exact then you did the math on paper.
When I was in high school in 72 I had a stripped down Honda 305 Super Hawk that I had already done a lot of things to it to make it go faster. We'd sit around talking smack about how fast our scooters were. That was the year I became familiar with green gas. I paid an eye watering 75 cents per gallon and the guy at the airport said, "I really shouldn't be selling you this". But he did and that scooter really ran! And the pistons didn't melt as so had many predicted. Fun fun! Back in the good old days.
@@tgmccoy1556 You were right after me, I flew from about 1980 to 1984 or so. I won't use last names here but if I remember, a guy named Leo was in charge and I remember Ladd and his son Brian. Old memory but I think tanker 69 crashed in 1979 and Leo lost about half of his crew including the A&P who usually worked on a Comanche that I owned. Again, not sure but I think I flew tanker 66 or maybe 60. Brings back a bunch of old memories.........
The father of one of my best friends was the maintenance manager for KLM at LAX when they operated direct flights between Amsterdam and L.A. with L-1649A Starliners via the "polar route." He said it was rare when they didn't have to replace at least one PRT and not uncommon to replace more than one after each flight. Engine changes weren't that unusual and there was a 24 hour delay before the return flight in the schedule for that reason.
Large marine two stroke diesels as the Silver RTA and the licenced Wartsila have PRT s . They add about 3 percent power to the crankshaft and improve specific fuel consumption. They have an overall efficiency of about 53 percent
Although never put to much use, the P&W R4360 14 cylinder corncob engine was designed originally to make use of turbo compounding. If you look at the rear accessory housing of ANY R4360, you will notice it has three large humps designed to house three fluid couplers, driven by exhaust turbines, adding torque to the crankshaft. I have seen only one example of a fully functional turbo compound R4360 as a cut-away trainer. That trainer in our museum was acquired from the Oregon Museum of Science and Industry where it was on display until the museum moved to it's present location. The other unique feature of this trainer was a two speed nose reduction propeller gear box. It was designed to actually shift gears at altitude. Totally unique and unbelievable until you see it in person. I have many stories concerning the restoration and operation of that engine trainer.
Very nice. Im working on video for the two cam disc setups for the R-4360. Id like to know more about this particular model, with a two speed gearbox. Ive got the ultimate book on the Major, Graham Whites book, do you know the dash number for this one?
@@eugeneoreilly9356 Pratt and Whitney never put an engine into production that had PRT's, but guarantee you, it'd be called something different lol. Pratt and Whitney did however produce a larger (the largest actually) production engine, the R-4360. That engine powered the last of the piston air liners right before jets come on the scene. Although it lasted into the 60s, maybe the 70s with the milirtary, it continues on at Reno and a few ground runners.
@@mikesmith7249 yes the big piston engines were relegated to the second tier because of the appearance of the turbojet.Napier had in development a flat twelve two stroke diesel for commercial purpose and had amassed a number of test hours with it in the nose of an Avro Lincoln bomber when the project was shelved in favour of the Eland jet which Napier also had in development.The Nomad exhaust gases fed a turbocharger underneath the engine and intake manifold pressures were in excess of 80 psi.Fuel could be injected and burned in the turbocharger outlet to give in excess of 150 kg of thrust.The engine was a 12 cyl of around 33 litres capacity and returned good fuel efficiency.There is only one complete engine in the museum of flight at East fortune Scotland.Worth a look if you are ever there.
Great video! Like many here, I'd never heard of this system, nor seen it on cutaways, to wonder what it was. I don't recall it being mentioned in Graham White's book either, though I assume it was, and I just don't remember. I'll be looking for it from now on - Thank you! How I'd love to have a set of old service manuals for the classic high-output piston engines - just to admire the mechanical drawings.
You're welcome. Im planning on doing a video about the integral suoerchargers. Specifically the difference between single speed and multispeed, variable speed and the drive mechanisms
I worked on the Navy SP-2H Neptune while assigned to patrol squadron, VP-65. The PRT seemed to be fairly reliable. Only recall one failure. During a maintenance engine run, one exhaust began puffing out smoke. Control tower radioed us to check our mixture setting. I guess they thought we were on full rich. At a glance, a PRT could be confused with a turbo supercharger.
Very cool. I worked P-3C's at NAS Jax, got to help tow the VP-5 SP-2H on duty as a gate guard to the paint hanger in preparation for CONA 2011. Very neat experience for a new airman! Thank you for your service.
It's interesting to see this concept in use in that time period on aircraft. On a relatively constant sustained RPM application like an aircraft engine this system makes all the sense in the world. Years ago I was involved in an energy recovery system development project for the DOD. It was specifically for use on the Humvee where we were asked to recover exhaust energy and transmit it back through the accessory drive belt. It seemed like a misguided idea somebody thought up in a pentagon meeting room with no mechanical experience or understanding of turbines. As I pointed out at the top of this comment, this is great on things like aircraft, also locomotives, ships, stationary power plants, maybe even long haul trucks. If I am remembering correctly from our benchmarking study they use a similar system on heavy equipment, large bulldozers, and mining equipment as well. It's not a great application on a Humvee which is running intermittently, at different speeds and under different loads. On a long march you would see some efficiency gains but in typical combat use it would just be another piece of mechanical complexity to worry about in a battle zone. This is really cool, thanks for posting.
Hey thanks! Although the R-3350 was equipped with a constant speed propeller, the propeller governor had its limits, and that range was smaller than later turboprop engines. The R-3350-91 had a rather large RPM range, per the RC-121D for manual, it was from 1400 to 2900 RPM. The beautiful thing is that because the system is equipped with a fluid coupling as opposed to a direct mechanical connection, HP return is not necessarily a function of engine RPM, its a function of engine exhaust pressure and velocity. Although, I should point out that engine exhaust pressure and velocity are strongly correlated with engine speed.
As a kid and teenager I remember the Canadian RCAF CP-107 Argus, a derivative of the Bristol Britannia with the original Proteus Turboprop engines replaced by the R3350 turbo compound radial piston engine. I remember hearing the turbo squeal over the roar of the four 18 cylinder engines at full power. they were eventually replaced by the P3 Orion derived /CP-140 Aurora in 1978.
I flew as a FE/FM for almost 9 years on our Unit's C-119G's with two R3350-89WA engines and then same aircraft later converted to C-119L's. They were supercharged and had water/alcohol injection for Takeoff. Each engine had three PRT's that generated 150 HP for each PRT at Takeoff Power for a total of 450 HP each engine. Our Unit, the 130th AW, was the very last Unit to fly the C-119's in the inventory and took them to the Bone Yard in September 1975. Two of our birds were preserved for static display .... 53-8084 at Little Rock and 53-8087 at the Special Forces Museum at Fort Bragg. The C-119L's were converted by replacing the Aeroproducts 4 blade prop with a more efficient 3 blade Hamilton Standard prop off of the C-121C Connies.
There is an old Navair training film on this system. At the time it was classified as a secret technology. Those turbines were very heavy and I once witnessed one being dropped from a check stand to the hangar deck. Cost the guy who dropped it a stripe.
If I recall, the metallurgy was always something everyone was working on improving. Because the entire systems reliability was based on the part with the shortest life, which was the turbine, the technology and research was kept hush hush. Even patents and research papers werent widely published.
@@jphoenix133 Indeed. And a center wing fillet fairing (aux) tank to transfer out to the engine(s) as needed. It seems, if memory serves, that aux tank was near to, or over 100 gal's on the "C" models that I was involved mostly with. We carried one, or two 55 gal drums, a hand-crank pump, and gerry-cans around in the planes to top up the tanks at stops with no oil. Individual engines using more than 8-10 gal's/hr in flt. was not uncommon.
Good video. You've made it sound more complex than it really was. In college, they taught us about these and they had a lot of problems in the field. You had to add power very slowly, since these could surge and overspeed and occasionally they just flew right apart. The R3350 turbo-compound had three blow-down turbines, and each added about 200 hp. You don't see this in automotive use because the extra complexity/cost doesn't justify the small amount of extra power.
There were 3 PRT's per engine and the latter version of the PRT delivered anout 375 hp per unit back to the crankshaft.I was at SGT in Americus Ga and we had 2 P2-V Neptunes with this engine and 4 spares in the early 80's.Both aircraft were flown in from Davis-Montham courtesy of RAFB who needed the C-141 flight control simulator back from SGT that they had donated in previous years.The P&W turbojets were fully operational too that were mounted on the wingtips.The Wright Cyclone was a workhorse for many decades in aviation.
So many people think the C.W. R-3350 is turbocharged, the term turbo compound is quite misleading since this is supercharged not turbocharged. This engine only has supercharging with PRT's not turbochargers.
Well, apropos of aircraft engines, turbo refers to a turbine extracting energy from the exhaust. Simce this particular system doesnt directly increase the pressure of the charge being inducted into the engine, it isnt a turbocharger, its a turbocompound. Also recall, not all R-3350 engines were turbocompounded. And you are correct, this engine is supercharged by means of an engine driven supercharger.
How true I was non-reving on the red eye when I woke to a noise like hail. There was a shower of sparks and parts that must have been the turbine buckets.
I was aware of the existence of these turbines but had no idea what they looked like. I'm genuinely surprised to see it's a smallish unit bolted to the side of the engine driven at an angle, I'd always envisaged something much more massive mounted inline with the crankshaft much like the supercharger.
Thats basically how a jet engine works, except instead of being linking by gearing, and powered by a reciprocating engine, it drived a compressor upstream of the flow
Fascinating concept! Inducing what would be lost power Mechanically direct to the crank via a hydraulic clutch , brilliant ! When did this come into service ? Can't recall any war era engines with this.
Correct, that Im aware of, only the B-29 flew the R-3350 into combat. The earliest versions used on the B-29 were not turbo-compounded. Im not certain when thr turbocompound first flew, but by the mid 50's they were definitely in use commercially
The R-3350 TC engines were first delivered with the L-1049A and B military variants of the Super Constellation starting around Nov. 1952. The TC engines were reserved for military use for more than a year presumably due to the war in Korea. The first deliveries of L-1049 to Eastern Airlines and TWA had the same version of the R-3350 used on the L-649 and L-749 Constellations. One interesting exception was 4x L-1049D freighters supposedly built for Seaboard Airlines because they had a military contract but were soon leased to BOAC for service to/from India. The first civil passenger L-1049C with TC engines were delivered in 1953.
@@givenfirstnamefamilyfirstn3935 Correct, however I am referring to later version of this system, as Developed in the late 20 early 30s by Bauer-Wach Parsons and others. In the early system to which you refer, the exhaust turbine was connected to its own shaft and propeller. In the later incarnation the turbine connected to the crankshaft of the engine producing the exhaust, making it possible to retro fit single engine ships effecting considerable economies .
This issue was the prime reason Keith Duckworth opposed turbos in F1; absent some very restrictive regulations, the IC engine simply becomes an exhaust generator for the turbine.
The heat in the exhaust gas is extracted? Around 1 minute in. FYI...the idea is to extract power from the exhaust stream, that would normally be wasted.
The engine installation had substantial advantages in range and horsepower over the Pratt & Whitney R-2800 setup as used on the DC-6, aircraft, unfortunately it wasn't very reliable.
I've heard these being referred to, as "parts recovery turbines," on account of exhaust valves breaking. Was the fluid coupling anything like the Chrysler Fluid Drive transmission setup? steve
They didn't break they melted. The engine was notorious for overheating from the beginning and then some berk strapped on some turbos bolted to layshafts basically - so instead of spitting the valve out, it bounced around inside the PRT, comprehensively destroying it, and came out as melty fragments. The really fun part is some bright spark made the engine cases out of a magnesium alloy - which if an engine burned, would cheerfully melt through the main wing spar on B29s. It was helped with the silverplate mods - fuel injection - which helped reduce lean mixtures (too little fuel = hot, too much = cold) but they still crapped themselves on a regular basis and loved coking the spark plugs.. There were 56 in each motor in some radials. And then some utter genius built the B36 and put them in *backwards* . 🤦♀️
@@rosiehawtrey Hi, So magnesium was actually in use quite often for both aircraft and engine applications. The primary reason was the magnesium is a very strong and lightweight material, and as you probably know, weight is a major factor in the design of aircraft. Magnesium does tend to burn very hot and a magnesium fire is notoriously difficult to extinguish once its started. I have a strong suspicion that the use of magnesium for its lightweight characteristics was, no pun intended 😆, 'weighed" against its proclivity for burning. Seems like the consensus was, if things are bad enough for the engine to catch fire, then what material the components were made of is of little consequence. Also, the R-3350 was never used on the B-36, that was the Pratt and Whitney R-4360.
The R-3350 was extensively redesigned during the later years of WWII and the military and civil versions used after the war were significantly better than those which powered the B-29.
@@dalecomer5951 Until Wright put on the turbo-supercharger...Northwestern lost 25% of their DC-7s due to incidents and over 701 people lost their lives.
does it also use a regular turbo stage ( turbine and compressor) and also this new turbine to crankshaft design? is that why it is called compound turbo? sorry im a little confused
There is an integral supercharger that is geared to the crankshaft, but otherwise no other turbosupercharger is used. This is because the engine was already as maximum boost with the integral suoercharger and the turbo compound. No the system is not new, it's mid 50s
the '749 manual I have for fs9 tells me that the superchargers used on the Connie make the engine less efficient when in the high setting and reduce the BMEP. So if BMEP output is reduced, what does a turbo actually give me at that point? is it that at high altitude, you lose less power than you would without?
Does it mention anything about how this relates to altitude? At lower altitudes this should be true because youd have to throttle the engine, whereas above 20k feet, with the superchargers in high, and throttles open I cant see why you'd lose efficiency.
This could have an efficiency impact on hybrid cars, and would be much simpler also, to use a turbo to drive an extra generator to charge the hybrid battery.
I learned from an old Flight Engineer that the Connie and Super Connie were the best three engined aircraft flying with KLM Royal Dutch Airlines 🤣🤣🤣. Just kidding, beautiful aircraft from a long gone and different era
I am actually looking for a Curtiss Wright R-3350 Engine. We currently use this engine to create wind at our testing laboratory. any leads would be appreciated I am located in Ontario Californa.
I'm sure that helps reduce vibration to the crank, but no that isn't the primary purpose. The fluid coupling is the component that transmits the power from the PRT to the crankshaft
@@mikesmith7249 Was actually thinking the other way around as regards the transmission of vibration. Since the crank is powered by impulses from the cylinders, it's rotational speed will not be absolutely constant, rather it can be thought to be "vibrating" torsionally. And since the turbine runs much faster, that vibration would be exasperated, with the turbine trying to be a flywheel for the whole engine, beating up it's gear train in the process.
@@mikesmith7249 That's what I was thinking. Have seen this elsewhere too. I have a 8 kW or so generator that was originally gear driven. It's similar to those found in aircraft of similar vintage to the radial engines, but this one was for a ground based vehicle of some kind. It's driven through a torsional spring with a simple friction clutch to damp vibration. Someone drove it with a single cylinder diesel engine, FAR exceeding the design vibration tolerance, and wrecked the spring.
Those were magnificent engines and were quite reliable but were very mantainace intensive. No wonder the jet engines took over as they were much easier to maintain as they had far fewer parts and inherently much simpler engines....
Why would you want to due that?? These engines had max blower boost already. That is why the PRT was added. The PRT was the last option to get more horsepower. If I remember they added around 150hp each? The were hydraulically coupled to the crankshaft. Well they were if you did not forget the stub shaft.
@@88SC Bob any idea what series engine it was used on? The early 3350's started out at about 2000hp in WWII. The compounds were a lot different especially in he supercharger. I cannot remember the max boost. At the time I was impressed how high it was.
@@jimandmandy I do not have the figures anymore. I think your figures are about right. I do remember a KB50 crew chief telling me they were pulling 54" in a 3 degree decent with 2 F100's on the drougue's calling for more speed. One of the jugs went right out leaving a hole in the cowling.
I find it difficult to believe some of the power figures thrown around the internet on the issue. Some quote up to 200 hp from one of these turbines. I don´t buy it. While there is quite a bit of energy in the exhaust gas itself it is primarily in the form of heat, which a turbine would have difficulty in extracting.
I know what the difference is between a supercharged and a turbocharged engine, but I'm still not quite sure what the difference was between a turbocharged engine on a normal fighter and the "power recovery" type of turbocharged engines on the Super Constellation and DC7. They called them "power recovery" turbines, but aren't all turbochargers, by definition, "power recovery" devices? What's special about the power recovery turbines on Super Constellations and DC7s that makes them different from other turbocharged engines?
A turbocharger uses exhaust gas to drive a tubine, which is mechanically coupled to a compressor. That compressor increases the pressure of air delivered to the intake manifold. Power recovery uses exhaust gas to drive a turbine, but this turbine isnt coupled to a compressor, its coupled to the crankshaft and adds hp back to the engine (or recovers power through heat). Also remember, turbocharing systems, whether standard or power recovery, dont require additional power to drive in the way a supercharger does, because of this, turbochargers increase the specific fuel consumption of the engine compared to a supercharger system. Hope this helps your understanding.
@@steveskouson9620 Yes, that is technically true, they arent free energy machines lol. What I meant was that, unlike a supercharger, which in some engine installations requies 600hp to drive, the turbocompound system does not have a parasitic relationship with the engine in terms of horsepower allocation. Considering the boost pressure the R-3350 ran at, Im not sure the backpressure created in the exhaust section was anything more than negligible.
@@mikesmith7249 Well, on a modern flat engine the exhaust system of a turbo engine runs quite a bit hotter than that of an NA engine. We're always paranoid about exhaust leaks on those things when we inspect them. In fact the most exciting-looking exhaust crack I've ever seen (well, except the one where some idiot had welded up a previous muffler leak without removing the muffler) was off the wastegate of a TIO-540. A weld had cracked about 30% of the way around where the pipe joined a flange.
I really don't see very much "hp being returned to the crankshaft" via that dainty little drive setup. I'm more inclined to believe that this apparatus's main function was to act more like a crankshaft-driven 'vacuum' on the exhaust manifold - which would in fact increase efficiency and boost hp as a result.
Well sir, if youve ever seen the shape of a compressor blade or a fan blade, and then that of a turbine blade, youll notice those shapes are very different from one another. Compressor blades and fan blades are designed in such a way that their primary purpose is to move air, while turbine blades are designed to extract the most amount of energy from a moving gas. With that said, these are designed as turbine blades, to receive the hot flow of exhaust gas and add HP to the crankshaft.
@@mikesmith7249 I did think about that you do have a point however I just don’t see very much horsepower being transmitted through that puny little drive. It defies logic.
@@76629online There are three PRTs and each delivered about 150hp, so 450 total. They accomplished this while causing negligible backpressure to the exhaust system. In addition, the drive shaft was more than 1/2" in diameter, although hollow, still very strong.
The R-3350 engine gets it's name, a Radial engine with 3,350 cubic inches of displacement, It had 18 cylinders, driving 3 turbines, or 6 cylinders totaling some 1,117 CI per turbine. That's a lot of flow, even at the low speed these engines ran at.
I will never understand why so many Americans can't properly pronounce TUR-BINE, as it is so clearly spelled. A TUR-BIN is not a TUR-BINE. I'm incredibly interested in the subject. It's just hard to enjoy when I here Turbin. Can someone please explain this to me? Why is it only Americans that do this? At least some Americans... I've heard other Americans pronounce it correctly.
150hp times three, for a total of 450hp. So, the Wright R-3350-91 as used on the RC-121D produced 3250hp at 2900 rpm based on the power curve provided in T.O. 1C-121D(R)-1. That figure represents 56.5 HG MAP with 115/145 fuel, and is limited to 5 minutes operation with CHT @ 260° C. Without the PRT, the engine would produce 2800hp with everything else the same, thats 14% less, or with PRT's, thats 14% more for free! Remember that using the PRTs doesnt cost more fuel, in fact the engine could produce the same power at a lower setting with PRT's which is why they increse the specific fuel consumption compared to the engine without it.
On the DC-7, we used BMEP, not manifold pressure. In the beginning g of the video, you can see at the top of the gear case what looks like a pressure carb, it’s actually a master control that provides input to the two fuel pumps that provide big psi fuel through direct injection to the cylinders. All this technology was in service to better sfc, but the jets quickly obsoleted all this amazing engineering.
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I was a member of an Air Guard unit that had C-121C Constellations for several years. Flying on one of those beauties at night I liked to sit by a window and watch the exhaust flames. I marveled at those turbines and wondered how they stayed together when the entire exhaust, flight hood (turbine cover) were orange hot while blue flame streamed from the exhaust. Fascinating.
Wow, awesome story. Thank you for sharing. Im a bit envious as Ill not get a chance to fly on a Connie, closest I ever get was flying the Orion. Anyway, thank you for your service, and for sharing your experience.
@@mikesmith7249 DC-7 Co-pilot here.got to make a night takeoff in a DC-7
with a load of 115/145 that we picked up in Reno/Stead. An F-15 in full burner had nothing on it.
@@tgmccoy1556 That's one motivated DC-7
I have such a turbine wheel at home. It serves as a foot for a desk lamp, it is really heavy. Hard to believe that those tiny blades make 150HP per turbine. The lamp is the reading lamp from the navigators desk of a Super Connie. 😃
Around 200 hp per turbine. And that is a seriously cool lamp~!
In this computerized world it always impresses me that these enormously complex machines were designed using pencils and paper. In those days the designers had to visualize the third dimension.
And it was amazing how fast they went from the drawing board to production.
Just found this I was a Copilot on DC-7s for an Airtanker outfit. Did that for 10 years. Much respect for the 3350 running them was as much art as science.
When I was in A&P school in the mid 90's we came onto these in one of my engine classes. One of the instructors started out in the mid 50's with the USAF and was pretty familiar with these as well as the 4360 in the B 36, which he crewed on for a while. Looking at the design I asked what it was worth considering the added weight and complexity, and he said almost 200 HP extra each. Knowing these were on the Connies airlines were flying, an extra 500 HP or so was a big advantage and let the airlines justify keeping those planes as long as it took for commercial jet aircraft to be worth the investment. That instructor had some fun stories about the B 36, like how when it took off each engine had a 100 gallon oil tank and each wing carried another 300 gallons of oil for topping off, when one landed there was little to no oil left, and that when parked under each engine they had a trailer with oil catch pans feeding into a tank. He said cylinders blowing off wasn't unusual, and they were a ton of hard work to keep flying. Large radials sound like a massive expensive pain, and it's little wonder, that like the horse when the early automobiles appeared, they were quickly gotten away from as soon as it was practical.
Fantastic story, thanks for sharing. I didnt know the B-36 was equipped with fuselage mounted oil tanks but it makes sense. I know that the C-54 and C-118 both had them. I imagine because engine oil was the limiting factor, not crew rest or fuel capacity. I wonder then about the NB-36H..
I'm sure that's correct. I used to work with a man who was a mechanic working on B17's in England during WW2. He told me that each engine had a nacelle mounted 37 gallon oil tank, and that those engines, even when new, would burn an easy gallon, sometime 2, per hour. Just the nature of radials I guess.
@@6h471 The DC-6 has 40 gallon oil tanks per engine, after a good days worth of flying, you'll probably put between 5 and 12 gallons of oil in each tank.
Wow just like my Harley
Makes sense 🤔, because a Harley is just 2 cylinders of a Radial engine.
Both V12 and radial engines did used a lot of oil but why did the radial engines burn so much oil? Can anybody explain me that?
I flew DC-7s in the early 80s as air tankers, they had the 3350s with PRTs. 3400 HP for takeoff, either 2800 or 2900 continuous (can't remember.......lol) with 115/145 (purple gas), a bit less with 100/130 (green gas).
The key to keeping the engine in one piece was to watch the temps closely and go easy on power changes. The other thing to watch was BMEP (Brake Mean Effective Pressure). If one cylinder goes low, there's a good chance that its exhaust valve is burning.
I only flew in hot weather (fire season) and with 115/145, the takeoff manifold pressure was in the high 50s. With 100/130, it was low 50s.
One thing I learned early on was if you mention PRTs to an A&P, you'll learn a whole new set of cusswords.........lol.
The 3350 is a pretty amazing engine considering it first ran in 1937, back then there wasn't any sort of computer drafting or even calculators. If close was good enough, you used a slide rule, if it needed exact then you did the math on paper.
When I was in high school in 72 I had a stripped down Honda 305 Super Hawk that I had already done a lot of things to it to make it go faster. We'd sit around talking smack about how fast our scooters were. That was the year I became familiar with green gas. I paid an eye watering 75 cents per gallon and the guy at the airport said, "I really shouldn't be selling you this".
But he did and that scooter really ran! And the pistons didn't melt as so had many predicted. Fun fun! Back in the good old days.
Don't worry, if it does burn an exhaust valve one of the Parts Recovery Turbines (PRT's) will pick it up and the mechanics can retrieve it later.
I flew DC-7s as Co-pilot for Butler/TBM in the 90's . got to really respect the 3350.
@@tgmccoy1556 You were right after me, I flew from about 1980 to 1984 or so.
I won't use last names here but if I remember, a guy named Leo was in charge and I remember Ladd and his son Brian.
Old memory but I think tanker 69 crashed in 1979 and Leo lost about half of his crew including the A&P who usually worked on a Comanche that I owned.
Again, not sure but I think I flew tanker 66 or maybe 60.
Brings back a bunch of old memories.........
Yep knew all those guys
Miss it
Awesome Video! That is amazing engineering 👍
I used to volunteer at the Robins AFB museum about 20 years ago! Cool, thanks!!!
The father of one of my best friends was the maintenance manager for KLM at LAX when they operated direct flights between Amsterdam and L.A. with L-1649A Starliners via the "polar route." He said it was rare when they didn't have to replace at least one PRT and not uncommon to replace more than one after each flight. Engine changes weren't that unusual and there was a 24 hour delay before the return flight in the schedule for that reason.
Excellent. Thank you for posting
Large marine two stroke diesels as the Silver RTA and the licenced Wartsila have PRT s . They add about 3 percent power to the crankshaft and improve specific fuel consumption. They have an overall efficiency of about 53 percent
I love how your first words are „All Wright“
Lol, even when I do the Jake videos that's how I start
Although never put to much use, the P&W R4360 14 cylinder corncob engine was designed originally to make use of turbo compounding. If you look at the rear accessory housing of ANY R4360, you will notice it has three large humps designed to house three fluid couplers, driven by exhaust turbines, adding torque to the crankshaft.
I have seen only one example of a fully functional turbo compound R4360 as a cut-away trainer. That trainer in our museum was acquired from the Oregon Museum of Science and Industry where it was on display until the museum moved to it's present location. The other unique feature of this trainer was a two speed nose reduction propeller gear box. It was designed to actually shift gears at altitude. Totally unique and unbelievable until you see it in person. I have many stories concerning the restoration and operation of that engine trainer.
Very nice. Im working on video for the two cam disc setups for the R-4360. Id like to know more about this particular model, with a two speed gearbox. Ive got the ultimate book on the Major, Graham Whites book, do you know the dash number for this one?
P&W R4360 had or has 28 cylinders.
P@w must have stolen Wright's thunder?
@@eugeneoreilly9356 Pratt and Whitney never put an engine into production that had PRT's, but guarantee you, it'd be called something different lol. Pratt and Whitney did however produce a larger (the largest actually) production engine, the R-4360. That engine powered the last of the piston air liners right before jets come on the scene. Although it lasted into the 60s, maybe the 70s with the milirtary, it continues on at Reno and a few ground runners.
@@mikesmith7249 yes the big piston engines were relegated to the second tier because of the appearance of the turbojet.Napier had in development a flat twelve two stroke diesel for commercial purpose and had amassed a number of test hours with it in the nose of an Avro Lincoln bomber when the project was shelved in favour of the Eland jet which Napier also had in development.The Nomad exhaust gases fed a turbocharger underneath the engine and intake manifold pressures were in excess of 80 psi.Fuel could be injected and burned in the turbocharger outlet to give in excess of 150 kg of thrust.The engine was a 12 cyl of around 33 litres capacity and returned good fuel efficiency.There is only one complete engine in the museum of flight at East fortune Scotland.Worth a look if you are ever there.
Great video! Like many here, I'd never heard of this system, nor seen it on cutaways, to wonder what it was. I don't recall it being mentioned in Graham White's book either, though I assume it was, and I just don't remember. I'll be looking for it from now on - Thank you! How I'd love to have a set of old service manuals for the classic high-output piston engines - just to admire the mechanical drawings.
Thanks, Always wondered about this system!
You're welcome. Im planning on doing a video about the integral suoerchargers. Specifically the difference between single speed and multispeed, variable speed and the drive mechanisms
@@mikesmith7249 Can't wait!
A huge capacity engine putting out a hellava lot of hot exhaust. 🔥 Every little bit helps.
Thanks - I grew up to the sound of runaway turbo compounds!
Awesome engineering
I worked on the Navy SP-2H Neptune while assigned to patrol squadron, VP-65. The PRT seemed to be fairly reliable. Only recall one failure. During a maintenance engine run, one exhaust began puffing out smoke. Control tower radioed us to check our mixture setting. I guess they thought we were on full rich. At a glance, a PRT could be confused with a turbo supercharger.
Very cool. I worked P-3C's at NAS Jax, got to help tow the VP-5 SP-2H on duty as a gate guard to the paint hanger in preparation for CONA 2011. Very neat experience for a new airman! Thank you for your service.
It's interesting to see this concept in use in that time period on aircraft. On a relatively constant sustained RPM application like an aircraft engine this system makes all the sense in the world.
Years ago I was involved in an energy recovery system development project for the DOD. It was specifically for use on the Humvee where we were asked to recover exhaust energy and transmit it back through the accessory drive belt. It seemed like a misguided idea somebody thought up in a pentagon meeting room with no mechanical experience or understanding of turbines. As I pointed out at the top of this comment, this is great on things like aircraft, also locomotives, ships, stationary power plants, maybe even long haul trucks. If I am remembering correctly from our benchmarking study they use a similar system on heavy equipment, large bulldozers, and mining equipment as well. It's not a great application on a Humvee which is running intermittently, at different speeds and under different loads. On a long march you would see some efficiency gains but in typical combat use it would just be another piece of mechanical complexity to worry about in a battle zone.
This is really cool, thanks for posting.
Hey thanks! Although the R-3350 was equipped with a constant speed propeller, the propeller governor had its limits, and that range was smaller than later turboprop engines.
The R-3350-91 had a rather large RPM range, per the RC-121D for manual, it was from 1400 to 2900 RPM. The beautiful thing is that because the system is equipped with a fluid coupling as opposed to a direct mechanical connection, HP return is not necessarily a function of engine RPM, its a function of engine exhaust pressure and velocity. Although, I should point out that engine exhaust pressure and velocity are strongly correlated with engine speed.
As a kid and teenager I remember the Canadian RCAF CP-107 Argus, a derivative of the Bristol Britannia with the original Proteus Turboprop engines replaced by the R3350 turbo compound radial piston engine. I remember hearing the turbo squeal over the roar of the four 18 cylinder engines at full power. they were eventually replaced by the P3 Orion derived /CP-140 Aurora in 1978.
Ive seen a few CP-140's at NAS Jax, they're definitely cool. I wish I could have seen the CP-107s
I flew as a FE/FM for almost 9 years on our Unit's C-119G's with two R3350-89WA engines and then same aircraft later converted to C-119L's. They were supercharged and had water/alcohol injection for Takeoff. Each engine had three PRT's that generated 150 HP for each PRT at Takeoff Power for a total of 450 HP each engine. Our Unit, the 130th AW, was the very last Unit to fly the C-119's in the inventory and took them to the Bone Yard in September 1975. Two of our birds were preserved for static display .... 53-8084 at Little Rock and 53-8087 at the Special Forces Museum at Fort Bragg. The C-119L's were converted by replacing the Aeroproducts 4 blade prop with a more efficient 3 blade Hamilton Standard prop off of the C-121C Connies.
Very interesting, I thought the Aeroproducts props were lighter and more efficient
thank you! first I hear of this :O
There is an old Navair training film on this system. At the time it was classified as a secret technology. Those turbines were very heavy and I once witnessed one being dropped from a check stand to the hangar deck. Cost the guy who dropped it a stripe.
If I recall, the metallurgy was always something everyone was working on improving. Because the entire systems reliability was based on the part with the shortest life, which was the turbine, the technology and research was kept hush hush. Even patents and research papers werent widely published.
Ouch! What a complicated system this was, wow!
Is that video on TH-cam?
I recall on DC-7s using raincoats to change the lowermost PRT as the oil rainshower was so great, a long time ago in a past life...
Wow, thanks for sharing. As hot as they were, and as fast as they turned, they did need a lot of oil.
I worked on DC-7s and concur with the oil bath scenario. Also saw a couple of prt fires. Those airplanes had 57 gallon oil tanks behind each engine 😃
@@jphoenix133 Indeed. And a center wing fillet fairing (aux) tank to transfer out to the engine(s) as needed. It seems, if memory serves, that aux tank was near to, or over 100 gal's on the "C" models that I was involved mostly with. We carried one, or two 55 gal drums, a hand-crank pump, and gerry-cans around in the planes to top up the tanks at stops with no oil. Individual engines using more than 8-10 gal's/hr in flt. was not uncommon.
Good video. You've made it sound more complex than it really was. In college, they taught us about these and they had a lot of problems in the field. You had to add power very slowly, since these could surge and overspeed and occasionally they just flew right apart. The R3350 turbo-compound had three blow-down turbines, and each added about 200 hp.
You don't see this in automotive use because the extra complexity/cost doesn't justify the small amount of extra power.
Detroit Diesel 60 series have their turbos geared in to both keep them spooled at low rpm, and to return power into the accessory drive gear train.
There were 3 PRT's per engine and the latter version of the PRT delivered anout 375 hp per unit back to the crankshaft.I was at SGT in Americus Ga and we had 2 P2-V Neptunes with this engine and 4 spares in the early 80's.Both aircraft were flown in from Davis-Montham courtesy of RAFB who needed the C-141 flight control simulator back from SGT that they had donated in previous years.The P&W turbojets were fully operational too that were mounted on the wingtips.The Wright Cyclone was a workhorse for many decades in aviation.
If I recall, the jets might have been Westinghouse J34 engines.
@@mikesmith7249 I'm sorry,been awhile,yes I believe you are correct.
P2V-4 turbo compound twins operating far out at sea must have kept the crews listening for every successful engine revolution?
So many people think the C.W. R-3350 is turbocharged, the term turbo compound is quite misleading since this is supercharged not turbocharged. This engine only has supercharging with PRT's not turbochargers.
Well, apropos of aircraft engines, turbo refers to a turbine extracting energy from the exhaust. Simce this particular system doesnt directly increase the pressure of the charge being inducted into the engine, it isnt a turbocharger, its a turbocompound. Also recall, not all R-3350 engines were turbocompounded.
And you are correct, this engine is supercharged by means of an engine driven supercharger.
Also known in the industry as 'Parts Recovery Turbines' due to the frequent breakdowns.
Also known as the "parts recovery turbine".
How true I was non-reving on the red eye when I woke to a noise like hail. There was a shower of sparks and parts that must have been the turbine buckets.
🤣
I was aware of the existence of these turbines but had no idea what they looked like.
I'm genuinely surprised to see it's a smallish unit bolted to the side of the engine driven at an angle, I'd always envisaged something much more massive mounted inline with the crankshaft much like the supercharger.
Thats basically how a jet engine works, except instead of being linking by gearing, and powered by a reciprocating engine, it drived a compressor upstream of the flow
@@mikesmith7249 This engine is more like a step on the way to evolving into a turboshaft.
@@Robwantsacurry turboshaft engines have a gas generator
i had no idea such a thing existed. fascinating. Am i seeing things or does the rear bank of pistons have a smaller diameter
Good video. As per the last picture , you showed, it looks like that there are two fluid coupling.
Kind correct me please?
Thanks.
There are actually three per engine
Fascinating concept! Inducing what would be lost power Mechanically direct to the crank via a hydraulic clutch , brilliant ! When did this come into service ? Can't recall any war era engines with this.
Correct, that Im aware of, only the B-29 flew the R-3350 into combat. The earliest versions used on the B-29 were not turbo-compounded.
Im not certain when thr turbocompound first flew, but by the mid 50's they were definitely in use commercially
The R-3350 TC engines were first delivered with the L-1049A and B military variants of the Super Constellation starting around Nov. 1952. The TC engines were reserved for military use for more than a year presumably due to the war in Korea. The first deliveries of L-1049 to Eastern Airlines and TWA had the same version of the R-3350 used on the L-649 and L-749 Constellations. One interesting exception was 4x L-1049D freighters supposedly built for Seaboard Airlines because they had a military contract but were soon leased to BOAC for service to/from India. The first civil passenger L-1049C with TC engines were delivered in 1953.
A similar system was used from the mid 1930 on marine steam reciprocating engines.
Eh… Olympic class liners in service from 1911?
@@givenfirstnamefamilyfirstn3935 Correct, however I am referring to later version of this system, as Developed in the late 20 early 30s by Bauer-Wach Parsons and others. In the early system to which you refer, the exhaust turbine was connected to its own shaft and propeller. In the later incarnation the turbine connected to the crankshaft of the engine producing the exhaust, making it possible to retro fit single engine ships effecting considerable economies .
This issue was the prime reason Keith Duckworth opposed turbos in F1; absent some very restrictive regulations, the IC engine simply becomes an exhaust generator for the turbine.
For an extreme example of that, look at the Napier Nomad 2
The heat in the exhaust gas is extracted? Around 1 minute in. FYI...the idea is to extract power from the exhaust stream, that would normally be wasted.
The engine installation had substantial advantages in range and horsepower over the Pratt & Whitney R-2800 setup as used on the DC-6, aircraft, unfortunately it wasn't very reliable.
Aren't they also super heavy?
Increase specific fuel consumption? Please explain. Are you just making things up?
I've heard these being referred to, as
"parts recovery turbines," on account
of exhaust valves breaking.
Was the fluid coupling anything like
the Chrysler Fluid Drive transmission
setup?
steve
They didn't break they melted. The engine was notorious for overheating from the beginning and then some berk strapped on some turbos bolted to layshafts basically - so instead of spitting the valve out, it bounced around inside the PRT, comprehensively destroying it, and came out as melty fragments. The really fun part is some bright spark made the engine cases out of a magnesium alloy - which if an engine burned, would cheerfully melt through the main wing spar on B29s.
It was helped with the silverplate mods - fuel injection - which helped reduce lean mixtures (too little fuel = hot, too much = cold) but they still crapped themselves on a regular basis and loved coking the spark plugs.. There were 56 in each motor in some radials.
And then some utter genius built the B36 and put them in *backwards* . 🤦♀️
@@rosiehawtrey Hi,
So magnesium was actually in use quite often for both aircraft and engine applications. The primary reason was the magnesium is a very strong and lightweight material, and as you probably know, weight is a major factor in the design of aircraft.
Magnesium does tend to burn very hot and a magnesium fire is notoriously difficult to extinguish once its started. I have a strong suspicion that the use of magnesium for its lightweight characteristics was, no pun intended 😆, 'weighed" against its proclivity for burning. Seems like the consensus was, if things are bad enough for the engine to catch fire, then what material the components were made of is of little consequence.
Also, the R-3350 was never used on the B-36, that was the Pratt and Whitney R-4360.
The R-3350 was extensively redesigned during the later years of WWII and the military and civil versions used after the war were significantly better than those which powered the B-29.
@@dalecomer5951 Until Wright put on the turbo-supercharger...Northwestern lost 25% of their DC-7s due to incidents and over 701 people lost their lives.
@@jamesholben9714 Total B.S.
The current Detroit Diesel DD16 big rig Diesel engine has a turbo compounder on it.
Detroit Diesel DD15s use this type of technology in turbo compounding form.
does it also use a regular turbo stage ( turbine and compressor) and also this new turbine to crankshaft design? is that why it is called compound turbo? sorry im a little confused
There is an integral supercharger that is geared to the crankshaft, but otherwise no other turbosupercharger is used. This is because the engine was already as maximum boost with the integral suoercharger and the turbo compound.
No the system is not new, it's mid 50s
the '749 manual I have for fs9 tells me that the superchargers used on the Connie make the engine less efficient when in the high setting and reduce the BMEP. So if BMEP output is reduced, what does a turbo actually give me at that point? is it that at high altitude, you lose less power than you would without?
Does it mention anything about how this relates to altitude? At lower altitudes this should be true because youd have to throttle the engine, whereas above 20k feet, with the superchargers in high, and throttles open I cant see why you'd lose efficiency.
This could have an efficiency impact on hybrid cars, and would be much simpler also, to use a turbo to drive an extra generator to charge the hybrid battery.
I don't think there's much excess enthalpy in the exhaust gas stream from an automotive engine.
Use to overhaul those, 1649 Connie project
They used this system on the Ryan Rainbow.
What's the Ryan Rainbow?
These vintage airplanes on static display all around the country do they get parts robbed off of them so other airplanes can fly?
I often wonder what a 4 stroke engine tuner could do with a factory boxed unit. Just to see what more development could have achieved.
I learned from an old Flight Engineer that the Connie and Super Connie were the best three engined aircraft flying with KLM Royal Dutch Airlines 🤣🤣🤣. Just kidding, beautiful aircraft from a long gone and different era
I'm curious about the viability of this system in an automotive application.
I've heard them referred to as Parts Recovery Turbines.😆
You need twin scroll technology in order to harvest those pulses without back pressure.
PRTs became more efficient at altitude because of the lower air pressure and less exhaust back pressure.
That seems to make sense.
Also, Franziskaner is good but its no Weihenstephaner
Didn't this engine set a distance record? The concept is used on the Detroit Diesel DD13/15 and the Volvo/Mack D13s
It was the powerplant used in a P2V Neptune by the name of the Truculant Turtle. It is currently on display at the National Naval Aviation Museum.
I am actually looking for a Curtiss Wright R-3350 Engine. We currently use this engine to create wind at our testing laboratory. any leads would be appreciated I am located in Ontario Californa.
I imagine the primary purpose of the fluid coupling is torsional vibration damping? Seems such a system wouldn't need an actual clutch function...
I'm sure that helps reduce vibration to the crank, but no that isn't the primary purpose. The fluid coupling is the component that transmits the power from the PRT to the crankshaft
@@mikesmith7249 Was actually thinking the other way around as regards the transmission of vibration. Since the crank is powered by impulses from the cylinders, it's rotational speed will not be absolutely constant, rather it can be thought to be "vibrating" torsionally. And since the turbine runs much faster, that vibration would be exasperated, with the turbine trying to be a flywheel for the whole engine, beating up it's gear train in the process.
@@realvanman1 oooh, I see. So the systems are mechanically independent so no transfer pf vibration
@@mikesmith7249 That's what I was thinking. Have seen this elsewhere too. I have a 8 kW or so generator that was originally gear driven. It's similar to those found in aircraft of similar vintage to the radial engines, but this one was for a ground based vehicle of some kind. It's driven through a torsional spring with a simple friction clutch to damp vibration. Someone drove it with a single cylinder diesel engine, FAR exceeding the design vibration tolerance, and wrecked the spring.
It probably allows the high speed turbine to mesh with the relatively low RPM of the 3,350 cubic inch radial engine.
Those were magnificent engines and were quite reliable but were very mantainace intensive. No wonder the jet engines took over as they were much easier to maintain as they had far fewer parts and inherently much simpler engines....
Not necessarily less parts afaik, just less uncommon parts.
Bill Gunston , the author, told us ...The piston engine is a mechanical miracle and the jet engine is a metallurgical miracle.
So a direct drive turbo with torque converters, got it.
Can't say I've ever heard of torque converters
@@mikesmith7249 it is a type of fluide coupler used in automobiles.
Question: would it be possible to fit one of these engines with a turbo-supercharger as well as the power recovery turbines?
Why would you want to due that?? These engines had max blower boost already. That is why the PRT was added. The PRT was the last option to get more horsepower. If I remember they added around 150hp each? The were hydraulically coupled to the crankshaft. Well they were if you did not forget the stub shaft.
Wright actually considered it. There’s a picture of the system mocked-up (or prototyped, not sure) I’m not sure if it was ever run.
@@88SC Bob any idea what series engine it was used on? The early 3350's started out at about 2000hp in WWII. The compounds were a lot different especially in he supercharger. I cannot remember the max boost. At the time I was impressed how high it was.
@@jayreiter268 Top boost resulted in about 60in manifold pressure and required 115/145 octane fuel, while with 52in manifold pressure, 100/130 octane.
@@jimandmandy I do not have the figures anymore. I think your figures are about right. I do remember a KB50 crew chief telling me they were pulling 54" in a 3 degree decent with 2 F100's on the drougue's calling for more speed. One of the jugs went right out leaving a hole in the cowling.
Times 3, for 150 horse each .
PARTS recovery turbine!
I find it difficult to believe some of the power figures thrown around the internet on the issue. Some quote up to 200 hp from one of these turbines. I don´t buy it. While there is quite a bit of energy in the exhaust gas itself it is primarily in the form of heat, which a turbine would have difficulty in extracting.
does it have one way clutch
There isnt a clutch in the drive train of the PRT, only the fluid coupling. There is however are clutch in the integral two speed supercharger.
Seems like the fluid coupling could act as a one-way clutch to allow the PRT to spool down when engine RPM is reduced.
@@dalecomer5951 i asked because of idle or low power settings of main engine, then engine gives power to prt because low exhaust gasses
I know what the difference is between a supercharged and a turbocharged engine, but I'm still not quite sure what the difference was between a turbocharged engine on a normal fighter and the "power recovery" type of turbocharged engines on the Super Constellation and DC7. They called them "power recovery" turbines, but aren't all turbochargers, by definition, "power recovery" devices? What's special about the power recovery turbines on Super Constellations and DC7s that makes them different from other turbocharged engines?
A turbocharger uses exhaust gas to drive a tubine, which is mechanically coupled to a compressor. That compressor increases the pressure of air delivered to the intake manifold.
Power recovery uses exhaust gas to drive a turbine, but this turbine isnt coupled to a compressor, its coupled to the crankshaft and adds hp back to the engine (or recovers power through heat).
Also remember, turbocharing systems, whether standard or power recovery, dont require additional power to drive in the way a supercharger does, because of this, turbochargers increase the specific fuel consumption of the engine compared to a supercharger system.
Hope this helps your understanding.
@@mikesmith7249,Turbochargers DO take power
to run. Added exhaust backpressure. Pretty
sure the "parts recovery turbine" did as well.
steve
@@steveskouson9620While this is true, the turbine will generally recover a lot more energy than it absorbs.
@@steveskouson9620 Yes, that is technically true, they arent free energy machines lol. What I meant was that, unlike a supercharger, which in some engine installations requies 600hp to drive, the turbocompound system does not have a parasitic relationship with the engine in terms of horsepower allocation.
Considering the boost pressure the R-3350 ran at, Im not sure the backpressure created in the exhaust section was anything more than negligible.
@@mikesmith7249 Well, on a modern flat engine the exhaust system of a turbo engine runs quite a bit hotter than that of an NA engine. We're always paranoid about exhaust leaks on those things when we inspect them. In fact the most exciting-looking exhaust crack I've ever seen (well, except the one where some idiot had welded up a previous muffler leak without removing the muffler) was off the wastegate of a TIO-540. A weld had cracked about 30% of the way around where the pipe joined a flange.
Where's the Fuel injection pumps sync. Bar..... don't see it.....????
When a DC-7 Flight engineer pointed it out to me and told me what it was I didn't believe him.
Sounds like you can trust him
Can't see the diagram on a cell ph
I really don't see very much "hp being returned to the crankshaft" via that dainty little drive setup. I'm more inclined to believe that this apparatus's main function was to act more like a crankshaft-driven 'vacuum' on the exhaust manifold - which would in fact increase efficiency and boost hp as a result.
Well sir, if youve ever seen the shape of a compressor blade or a fan blade, and then that of a turbine blade, youll notice those shapes are very different from one another.
Compressor blades and fan blades are designed in such a way that their primary purpose is to move air, while turbine blades are designed to extract the most amount of energy from a moving gas. With that said, these are designed as turbine blades, to receive the hot flow of exhaust gas and add HP to the crankshaft.
@@mikesmith7249 I did think about that you do have a point however I just don’t see very much horsepower being transmitted through that puny little drive. It defies logic.
@@76629online There are three PRTs and each delivered about 150hp, so 450 total. They accomplished this while causing negligible backpressure to the exhaust system. In addition, the drive shaft was more than 1/2" in diameter, although hollow, still very strong.
The R-3350 engine gets it's name, a Radial engine with 3,350 cubic inches of displacement, It had 18 cylinders, driving 3 turbines, or 6 cylinders totaling some 1,117 CI per turbine. That's a lot of flow, even at the low speed these engines ran at.
If you ever see one, dainty would not come to mind
Good info, camera work and editing needs work
Lol yeah, Im a mechanic and inspector, I dont know the first thing about video production
@@mikesmith7249 - You did fine!
*Velocity
Seems like a lot of complexity for very little gain .
I will never understand why so many Americans can't properly pronounce TUR-BINE, as it is so clearly spelled. A TUR-BIN is not a TUR-BINE. I'm incredibly interested in the subject. It's just hard to enjoy when I here Turbin. Can someone please explain this to me? Why is it only Americans that do this? At least some Americans... I've heard other Americans pronounce it correctly.
A good overview of an interesting topic but a poorly produced video.
Sure seems like a whole pile of engineering for 150hp.
150hp times three, for a total of 450hp. So, the Wright R-3350-91 as used on the RC-121D produced 3250hp at 2900 rpm based on the power curve provided in T.O. 1C-121D(R)-1. That figure represents 56.5 HG MAP with 115/145 fuel, and is limited to 5 minutes operation with CHT @ 260° C.
Without the PRT, the engine would produce 2800hp with everything else the same, thats 14% less, or with PRT's, thats 14% more for free! Remember that using the PRTs doesnt cost more fuel, in fact the engine could produce the same power at a lower setting with PRT's which is why they increse the specific fuel consumption compared to the engine without it.
On the DC-7, we used BMEP, not manifold pressure. In the beginning g of the video, you can see at the top of the gear case what looks like a pressure carb, it’s actually a master control that provides input to the two fuel pumps that provide big psi fuel through direct injection to the cylinders. All this technology was in service to better sfc, but the jets quickly obsoleted all this amazing engineering.
You had me till you went vertiphone.
Never record like that, it waste the camera.
I have no idea what that means