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(CAD) 28 Cyl P&W R-4360

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Bentwings

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I’d like to hear more about this project. I just spent the better part of two days researching and asking questions on why and how the link rod system worked. I now know that it was a cure for vibration that was caused by the weight reduction in the crankshaft. For a model this complex feature probably won’t be necessary as the material doesn’t “scale” as far as strength is concerned. In other wards the tensile strength as well as stiffness modulus of elasticity will be the same just the parts will be much smaller and not subject to the huge power the full sized one made. You rarely se crankshaft failures in small engines like mowers and model aircraft. Being a hot fodder adding big supercharger and a stiff load of nitro was my thing in my early years yes I destroyed a number of engines rather spectacularly but this motor would be hard pressed to make 15 hp. You see garden tractors that run for 30 plus years that have had little maintenance on them. So strength is probably not an issue. I can see where machining tolerance might be but that hasn’t happened yet.
so I’d really like to be involved with this conversation. I to have extensive cad as well as tool making and engineering experience. This design is daunting no doubt. I haven’t really started yet as I have to close out two of my other expensive hobbies first.

if anyone is interested post a reply and maybe we can get together by email. I don’t do social media so that’s not a good way to contact me

byron
 

Bentwings

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Ray-
not derailing my thread at all =) I love to hear the stories. I've heard it said that at a META power check in a maintenance hanger, if you were standing in the wrong spot you would be struggling just to breathe...one day I hope to experience the real thing, but until then, this is what I have =)

- Ryan
I have to reply to my own reply. So here goes.

we now have decided on 4 rows of seven. Then someone says how are we going to cool this ? Som3 engineer raises his hand and says well we can just twist the whole motor. That will open up natural cooling paths. Fortunately we as modelers don’t have to deal with this.....yet. But now you have rotated the gangs of cylinders parallel to the crank. Fine that works until another guy says well, if we just twist the cylinders a little we can have even better cooling.......but wait, the cylinders don’t just twist about. They are not in line with the crankshaft rod journals. So what is to be done. the piston wrist pin is now not parallel to a rod journal. I haven’t figured this out yet. I scoured through the 4360 book but I didn’t find an answer to this , I hope it’s not some simple piece of geometry 8 missed. I can see the rod having to turn the piston slightly but you would be asking fo rod and piston failures. My mind is scrambled b6 looking at all these drawings so I may have to just lay this out on cad and run a simulation to see if there is interference. I’m goin* to look a little further first. I sure don’t want to machine a whole crankcase only to find it won’t work. Until later.,
byron
 

Peter Twissell

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Re. Movable counterweight sections:
It is my understanding that the moveable parts were added to the counterweights to correct a torsional vibration problem in the dual row and four row engines. The small amount of movement allows the effective counterweight mass to be reduced for small displacement, high frequency crankshaft torsional modes. The moving parts are suspended in oil and that provides damping, preventing the vibration mode from propagating to the extent that it caused fatigue.
See also Stockbridge Dampers.
For a model engine, the vibration modes will be entirely different. Unless the engine is expected to run under load for many hours, the additional complication of adding the moveable counterweights cannot be justified from a functional perspective.
Of course, there are some among us who would enjoy making the whole engine as close to scale as possible!
I believe the term is "masochists".
 

Bentwings

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After investigating thes incredible things I’m in complete agreement. I’m not sure “ scale” ones would be effective and may actually do harm. They certainly would if they came apart! Scale is nice but “invisible scale” is not my thing.
 

Bentwings

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I also looked up the stock bridge dampers but again most of us simply could not afford the labor to even think about this. my experience in hot rod R.C warbirds has shown that simply adding a little material solved the vibration problems. Even my tuned pipe exhaust systems suffered some vibration issues but it was not a big deal to add a bit larger coupler to the pipe and make a bit thicker material to the exhaust flanges. Should I build a 27 cyl radial I’ll leave the movable dampers off until testing is complete. It will be enough work just getting it all together. From what I’ve seen so far these radials run pretty smoothly as they are.
 

Bentwings

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I’ve spent the better part of two days chasing info on these. The guy that was hired to fix the vibration issue said the crankshaft was too heave so in p&w plan they let him cut weight off the counter weights which helped in the overall weight. Apparently this vibration issue was noted in other applications so it was a natural to add them here he also did the same to the r2800 although I couldn’t find any pictures or other documentation. There is note of it however. Also a note that the pivot bearings failed due to fretting Even though the bearings were carefully coated. I wonder how these were replaced in the field . It’s pretty tight in there. Maybe there was a special tool or the entire half or end of the motor was removed. I thought cars had a lot of nuts and bolts. In the search I also found that high g turns put excessive loads on the motor due to the gyro effect of the prop. I had never thought of that. There were a number of cases where prop had problems that caused the entire motor to be ripped off. The crankcase and motor mounts were strengthened to fix this issue. My son’sRCP 51 tore the prop hub up and nearly ripped that motor out before I got it stopped. Tore up a $30 prop and a$150 spinner. R.C. models aren’t cheap either. I’ve seen a number of radials on models but they run pretty smooth compared to to two stroke gas motors. That P51 has a 5.8 cu in two stroke advertised hp is around 6-7 . It definitely makes that. It will squash the gear strut all the way down under full power. 45+ pounds thrust.
 

Bentwings

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I’ve spent the better part of two days chasing info on these. The guy that was hired to fix the vibration issue said the crankshaft was too heave so in p&w plan they let him cut weight off the counter weights which helped in the overall weight. Apparently this vibration issue was noted in other applications so it was a natural to add them here he also did the same to the r2800 although I couldn’t find any pictures or other documentation. There is note of it however. Also a note that the pivot bearings failed due to fretting Even though the bearings were carefully coated. I wonder how these were replaced in the field . It’s pretty tight in there. Maybe there was a special tool or the entire half or end of the motor was removed. I thought cars had a lot of nuts and bolts. In the search I also found that high g turns put excessive loads on the motor due to the gyro effect of the prop. I had never thought of that. There were a number of cases where prop had problems that caused the entire motor to be ripped off. The crankcase and motor mounts were strengthened to fix this issue. My son’sRCP 51 tore the prop hub up and nearly ripped that motor out before I got it stopped. Tore up a $30 prop and a$150 spinner. R.C. models aren’t cheap either. I’ve seen a number of radials on models but they run pretty smooth compared to to two stroke gas motors. That P51 has a 5.8 cu in two stroke advertised hp is around 6-7 . It definitely makes that. It will squash the gear strut all the way down under full power. 45+ pounds thrust.
I don’t quite understand stand what limits travel on these. There are no dimensions on the patent drawings.
 

Bentwings

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Well, I promised (threatened?) that I would start a WIP for my probably long-running design process for a scale Pratt & Whitney R-4360.

For anyone curious, the R-4360 is considered the largest piston engine to ever go into production for airplanes. It was used on a variety of aircraft at and after the end of World War II, and while thousands were manufactured, most were scrapped when the military no longer needed them due to the introduction of the jet age. Few remain, and fewer still are still flying. Most are in museums as static displays, many were even cut away to show the interior workings.

In the past couple of years I gained a sort of passionate love for this 28 cylinder radial engine that my girlfriend is probably a little jealous of. I have done a lot of research on the engine, and am always doing more. I feel the best way to show this beast a proper respect is to try and develop a working scale model.

Countless design decisions will be forthcoming, and I welcome input from all corners of the forum on anything that sounds or looks questionable. While I intend to build this behemoth of a model, I currently have no shop, no machines, and very rusty skills. If something looks like it will be impossible to machine, please don't hesitate to speak up.

The full-scale R-4360 sports some utterly astounding statistics. 4,363 cubic inches of displacement, 28 cylinders arranged in 4 rows of 7 cylinders, with 4 magnetos driving them. It 'sipped' upwards of 100 gallons of 108 octane fuel an hour (try that with today's prices!) all metered from a single pressure carburetor. Each cylinder sported a 5.75 inch bore with a 6 inch stroke, giving a 6.7:1 compression ratio and fired two spark plugs to ensure the cavernous compression chamber ignited evenly and fully. Intake ports were mounted on the top of the chamber, with exhaust out the side (analysis done since have suggested it would have been far more efficient to switch these two, and would have solved some of the intricate heat problems they had). This entire machine was air-cooled, requiring an astonishing amount of air to flow through the cooling fins, and indeed a lot of designs were tried to get the optimal cooling. The 3000-3500 horses were caged in a package that measured 55 inches in diameter and 96.5 inches long, weighing 3,870 pounds dry.

In military applications, the Wasp Major as it was known, was used in a variety of aircraft, from experimental to production. A list of aircraft that used this engine can be found on the following wikipedia article: Pratt & Whitney R-4360 Wasp Major - Wikipedia

Perhaps most notably was the F2G "Super" Corsair (Not the much more popular F4U Corsair, but very similar). Postwar, Several F2G's were converted into racers that dominated the air races until a tragic accident shut down the Unlimited Class until the 1960's. Since then, one Super Corsair named the Dreadnought took away numerous finishes, until it crashed in the mid 1980's. I believe Dreadnought is nearing rebuild, but that information may be inaccurate.

My goals with this design are to create a 1/6th scale version of the Wasp Major, though many design concessions will have to be made to ensure that it will be a running model. I will attempt to document the process of development, and as I am using a CAD program it should be easy for me to go back and make adjustments as required (provided I follow proper CAD procedures, something I often fail to do)

Again, if anyone sees anything questionable, has input, or any questions in general, please don't hesitate to jump in and help me. I apologize for this being a CAD work (for now!) and not a real machine, but some time down the road I will start another WIP when I have sufficient tools and skills to give the real thing a try.

Cheers,
- Ryan
i too have a strong interest in the motor as well as building the metal scale model. I’ve also looked into plastic fabrication. Even 3D printing. The man I chatted with indicated that he could do as much of the assembled cad model as I wanted. He said something about the set is that he can control adjacent surfaces so getting it apart would not be too difficult he said making parts on a tree like model parts was a waste of a lot of material in the branch tabs that is more common to molds so that sounds encouraging.

now I just have to sit down and creat solid works models them assemble them in an assembly. He said that’s all he needs. Then he could give an estimated cost.
 

mayhugh1

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Have you seen this:


The first post has a link to the builder's website that may be of interest.

Terry
 

Bentwings

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Well, I promised (threatened?) that I would start a WIP for my probably long-running design process for a scale Pratt & Whitney R-4360.

For anyone curious, the R-4360 is considered the largest piston engine to ever go into production for airplanes. It was used on a variety of aircraft at and after the end of World War II, and while thousands were manufactured, most were scrapped when the military no longer needed them due to the introduction of the jet age. Few remain, and fewer still are still flying. Most are in museums as static displays, many were even cut away to show the interior workings.

In the past couple of years I gained a sort of passionate love for this 28 cylinder radial engine that my girlfriend is probably a little jealous of. I have done a lot of research on the engine, and am always doing more. I feel the best way to show this beast a proper respect is to try and develop a working scale model.

Countless design decisions will be forthcoming, and I welcome input from all corners of the forum on anything that sounds or looks questionable. While I intend to build this behemoth of a model, I currently have no shop, no machines, and very rusty skills. If something looks like it will be impossible to machine, please don't hesitate to speak up.

The full-scale R-4360 sports some utterly astounding statistics. 4,363 cubic inches of displacement, 28 cylinders arranged in 4 rows of 7 cylinders, with 4 magnetos driving them. It 'sipped' upwards of 100 gallons of 108 octane fuel an hour (try that with today's prices!) all metered from a single pressure carburetor. Each cylinder sported a 5.75 inch bore with a 6 inch stroke, giving a 6.7:1 compression ratio and fired two spark plugs to ensure the cavernous compression chamber ignited evenly and fully. Intake ports were mounted on the top of the chamber, with exhaust out the side (analysis done since have suggested it would have been far more efficient to switch these two, and would have solved some of the intricate heat problems they had). This entire machine was air-cooled, requiring an astonishing amount of air to flow through the cooling fins, and indeed a lot of designs were tried to get the optimal cooling. The 3000-3500 horses were caged in a package that measured 55 inches in diameter and 96.5 inches long, weighing 3,870 pounds dry.

In military applications, the Wasp Major as it was known, was used in a variety of aircraft, from experimental to production. A list of aircraft that used this engine can be found on the following wikipedia article: Pratt & Whitney R-4360 Wasp Major - Wikipedia

Perhaps most notably was the F2G "Super" Corsair (Not the much more popular F4U Corsair, but very similar). Postwar, Several F2G's were converted into racers that dominated the air races until a tragic accident shut down the Unlimited Class until the 1960's. Since then, one Super Corsair named the Dreadnought took away numerous finishes, until it crashed in the mid 1980's. I believe Dreadnought is nearing rebuild, but that information may be inaccurate.

My goals with this design are to create a 1/6th scale version of the Wasp Major, though many design concessions will have to be made to ensure that it will be a running model. I will attempt to document the process of development, and as I am using a CAD program it should be easy for me to go back and make adjustments as required (provided I follow proper CAD procedures, something I often fail to do)

Again, if anyone sees anything questionable, has input, or any questions in general, please don't hesitate to jump in and help me. I apologize for this being a CAD work (for now!) and not a real machine, but some time down the road I will start another WIP when I have sufficient tools and skills to give the real thing a try.

Cheers,
- Ryan
 

Bentwings

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I’m a Corsair enthusiast too. I’ve had a model in the family for over 60 years.
at one point I built a 1/6 model fo the F4u-1d not much difference just opinions I think. This was built before everybody had one. I tried to follow and scale it off a Bunker Hill squadron. I was at an event and an elderly gentleman came over and said he really liked my model but there was an error in the markings. Turns out it was his group. So I did to send me pictures and I’ll repaint it. So Idid. He met me at another even5 and was just floored as it was exactly like his group. I had him come out and be my spotter and crewchief while I flew the demonstration. I don’t think I’ve ever seen anyone that thrilled. We took pictures and exchanged them through the mail. I built this plane well before they became ho hum attractions at model meets especially this size. Interesting fact no one in the club would help fly it as it was a very striking and large model. I had not flown for years but had talked at length with my father in law who flew them during the war and afterwards. He always sail use lots of rudder when you take off so my first flight I had full right rudder in before it left the ground. It kinda slide around the first left turn until I let up on the rudder. I flew it for 13 years. I drill have my log book. It’s over “ thick double sided pages. I broke a few parts hear and there but no crashes. I was going to make it into an F2G which would only have entailed adding few inches to the nose and a different air scoop. And a couple inches to the vertical stabilizer. I won five scale events so I had five kill markers on it. But I never did.if 8 ever built another I certainly would. I was fortunate to see the red and white racer fly at Osgosh, and the sound of that 4360 still rings in my ears. It’s a very complex. Model. There are some nice kits out now super expensive. Probably $10 grand for the plane and $7-8 for the Moki 400 radial. Prop is several hundred more. I’ll build a motor before the plane just to run at events. Just for the enjoyment of doing it.
anyway I’m going to get Solid works fired up and make som minor changes to the home screen.
 

Bentwings

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I was part of a bunch of scale warbird modelers for awhile. We tried to make our planes as close as possible. My constant thing was panel lines. As normally done on models in fully size would be terrible. If you look at the vintage planes you can see the removable pieces but even 20-30 feet away they nearly disappear. Just look up close next time you can and you will see there is less gap than cars have even today. Anyway I needed a gun sight on the Corsair that kinda looked scale. I had numerous pictures too so one night I just started making dome thing that looked real.it in reality was terrible, but at an event one judge side it was remarkably realistic.! I somet8mes kept a towel over the cockpit so people couldn’t see it. It had some wire like things like battery or power connection a goofy looking screen with crosshairs and a couple circles.... all pure imagination but many liked it . So some times if it looks scale maybe it is.

back to the crank. It’s going to be what actually balances according to standard practice. It’s going to be tough enough to make in the first place. I can invision trying to remove excess metal from s finished crank after the fact. It may require a special fixture just to hold it. I haven’t got that far yet so I’ll have to deal with it when the time comes. Hopefully dorm cad pictures will show up her.

byron
 

Bentwings

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Have you seen this:


The first post has a link to the builder's website that may be of interest.

Terry
im really glad there are others interested in an operating model of this engine.. I searched far and wide but only found some minor attempts. Not even a plastic model. Other than outline stuff. I found that Ltggo actually made a model of it but it was never released as there weren’t the 10, 000. Interests in it to make it a production model.
I found I have to reconfigure my cad since the computer update. My lap top can’t handle the program at all. I should have made an offer on my son’s laptop but it was just to9 much money. I don’t have my computer on the internet to avoid hacks and virus invasion. I’ll be able to export to a memory stick and jpeg to my iPad I think. I’ll have to see maybe I can get a better printer too. The heat index is 99 deg going to over 100 tomorrow. Just got in from afternoon walk with m6 dog. It’s hot and sticky. The grass is wet still from morning dew.
 

Bentwings

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Crankshaft, Revision 0

After reading all of the fun language that is a patent, two sayings came to mind. One, I've heard a few times in the various places I've been reading about machining engines. The other is a fairly popular one. Nike's "Just Do It", and "Start with a chunk of metal, and machine off anything that doesn't look like a [insert part, in this case crankshaft]"

A Crankshaft is effectively a long cylinder, with additional cylinder offset from its center line by 1/2 the length of the stroke. Where these offsets are, the main cylinder is cut away, to permit the rod for that crank throw to pass through the crankshaft's center line (If it couldn't, your engine wouldn't run very long. Half a turn at most.)

I have no information to go by for how thick the rods are. But what seems like a good guess to me, is about half of the diameter of the piston. My pistons are 0.9583 inches bore, so I'll use 0.479... naw, we'll just make it a half inch thick. I can always drop it to 3/8's later if I need to. If my rods are a half inch thick then by necessity my master rod journals need to be a half inch long, perhaps slightly longer. I'll add 1/32th of an inch to either side as a sort of buffer. Now, the patent drawing for the sideview of the crankshaft (patent is no. 2,426,879, I'm referring to Figure 21) shows lots of fine details, but being a patent, doesn't have dimensions. One notable thing is that the centerline bearing journals are bigger than the master rod journals, thus the 'long cylinder in the middle' is bigger than the master rod pin diameter. I can infer from a scale, assuming the patent drawing is to scale, that the diameter at the bearing is about 35% larger than that of the master rod journal.

... I talk a lot.

Anyway, while measuring that tidbit I found that at the scale I happened to print this image, the width of the crankshaft master rod journal pins is actually a half inch. this is a bizarre coincidence, but I'll take what I'm given! I can use this to get some other basic measurements with ease.

Anyone who saw my original post in the Questions thread regarding split gears will understand that I'm going to likely run into issues if I make this a single piece crankshaft. For now, I will design it as single piece, because it will give me a better visual idea of how I might be able to split it for a multi piece.

A basic layup of all those 'cylinders':




Obviously something's missing - there's nothing nearly strong enough actually holding the m/r journals in place but a thin piece of metal. I did warn that it was a basic layup. Of note in the second image is that each row is offset by 180 degrees, plus the offset between cylinders, of 12+6/7 degrees. this works out to 192.85 and change degrees, which allows each bank to fire on the opposite side of the bank before it, thus evening out vibration. This will make more sense when we get to firing order much later. (A preview of the firing order is visible at http://moozorzica.com/engines/4360order.jpg)

After some basic touchup, we have something that looks a bit more like a basic crankshaft :


This seems workable for now, so I'll leave it at this. Being as this is the first part, it's subject to great changes... hopefully not too badly, though.

I tried to keep the design minimal. I could have done the interconnects in that crazy half-round style they like to do, but this method will be way easier to machine, and will also lend itself to breaking down into multipart easier.

Based on this, I have : master rod thickness: 0.5", master rod journal diameter 0.435", master bearing diameters 0.5", 1/32" buffer on either end of master rod journals, all appropriate angular offsets between rows, etc. The overall crankshaft ends up being 7.200" long in its present design.

Next up: master rods. These are two-piece designs, that clamp together around the master rod bearing (which are also split bearings but I am leaning towards a multipart crankshaft, in such a way that i can slip the m/r journal bearings in one piece, way cheaper that route) and will require attach points for the other 6 slave rods, in each row. The Wasp Major has two of these actually passing through the bolts that hold the m/r halves together, which I'm sure I can manage, but will require custom made bolts.

This is enough for tonight. Thoughts on whether this would be machinable as one piece? a lot of pieces? Think I'd just end up making a bunch of scrap pieces in the process? I'd love to hear from you.

Cheers,
- Ryan
I ve now spent a full week everyday looking and studying this motor-engine. I happened to run into an old friend I ran dragster with. NHRA in their constant missing the things that brought fans to the races ended the top gas dragsters these had to run pump gas or the new race gas. We ran this class for a number of years then the twin engine cars arrived. They would have needed some new changes but not elimination of one of the greatest fan pleasers these looked like a big diesel was getting ready with billowing black clouds of exhaust. We had to run very rich idle as there was no accelerator pump in the fuel injection. If you didn’t the motor would sneeze on take off.
well so the idea of coupling the motors came up we already had a new coupler just for this and I had a second motor all ready to go. So thinking after the fact I thought it might be possible to couple two 7 cylinder radials back to back. You would need reverse rotation cams and ignition firing order but those are not hard to do. Modern cars use a flex plate only 1/8” thick to handle hundreds of hp. So maybe a 1/16” or even thinner flex plate made from 4130 sheet readily available from race car shops work for this. After all most of these radials only make 6-7 hp each. Looking at the real 4360 crankshaft it looks like it was married to the 7 cylinder crank at the center main bearing. It would still require a new center bearing but it’s within building process. Once I get some dimensions I’ll look further into this. I welcome any comments.
 

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I remember the 4360's. Often heard C-124 crews radio that they were sending an engineer into the wing to perform maintenance or inspections during flight. We once were diverted in flight to escort a C-124 with 4360's that had an engine fire enroute to Kwajelin. We could see the glow miles before we caught up to them. With only three of their engines going we had difficulty slowing down in our Navy VC-118 with R2800's. All turned out well fortunately.
 

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I remember the 4360's. Often heard C-124 crews radio that they were sending an engineer into the wing to perform maintenance or inspections during flight. We once were diverted in flight to escort a C-124 with 4360's that had an engine fire enroute to Kwajelin. We could see the glow miles before we caught up to them. With only three of their engines going we had difficulty slowing down in our Navy VC-118 with R2800's. All turned out well fortunately.
I read an account of a flight engineer crawling out in the wig to replace a burned out generator. Bag of tools and a big generator. Must have been an ordeal even then. Terribly noisy.
 

Master

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The C-124 was a huge airplane. I have heard similar stories. I think the number two and three engines were accessible in flight. Not sure of the two outboards. The C-124 was a real Air Force workhorse. Pretty slow though. On occasion we could see them flying below us.
 

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Well, I promised (threatened?) that I would start a WIP for my probably long-running design process for a scale Pratt & Whitney R-4360.

For anyone curious, the R-4360 is considered the largest piston engine to ever go into production for airplanes. It was used on a variety of aircraft at and after the end of World War II, and while thousands were manufactured, most were scrapped when the military no longer needed them due to the introduction of the jet age. Few remain, and fewer still are still flying. Most are in museums as static displays, many were even cut away to show the interior workings.

In the past couple of years I gained a sort of passionate love for this 28 cylinder radial engine that my girlfriend is probably a little jealous of. I have done a lot of research on the engine, and am always doing more. I feel the best way to show this beast a proper respect is to try and develop a working scale model.

Countless design decisions will be forthcoming, and I welcome input from all corners of the forum on anything that sounds or looks questionable. While I intend to build this behemoth of a model, I currently have no shop, no machines, and very rusty skills. If something looks like it will be impossible to machine, please don't hesitate to speak up.

The full-scale R-4360 sports some utterly astounding statistics. 4,363 cubic inches of displacement, 28 cylinders arranged in 4 rows of 7 cylinders, with 4 magnetos driving them. It 'sipped' upwards of 100 gallons of 108 octane fuel an hour (try that with today's prices!) all metered from a single pressure carburetor. Each cylinder sported a 5.75 inch bore with a 6 inch stroke, giving a 6.7:1 compression ratio and fired two spark plugs to ensure the cavernous compression chamber ignited evenly and fully. Intake ports were mounted on the top of the chamber, with exhaust out the side (analysis done since have suggested it would have been far more efficient to switch these two, and would have solved some of the intricate heat problems they had). This entire machine was air-cooled, requiring an astonishing amount of air to flow through the cooling fins, and indeed a lot of designs were tried to get the optimal cooling. The 3000-3500 horses were caged in a package that measured 55 inches in diameter and 96.5 inches long, weighing 3,870 pounds dry.

In military applications, the Wasp Major as it was known, was used in a variety of aircraft, from experimental to production. A list of aircraft that used this engine can be found on the following wikipedia article: Pratt & Whitney R-4360 Wasp Major - Wikipedia

Perhaps most notably was the F2G "Super" Corsair (Not the much more popular F4U Corsair, but very similar). Postwar, Several F2G's were converted into racers that dominated the air races until a tragic accident shut down the Unlimited Class until the 1960's. Since then, one Super Corsair named the Dreadnought took away numerous finishes, until it crashed in the mid 1980's. I believe Dreadnought is nearing rebuild, but that information may be inaccurate.

My goals with this design are to create a 1/6th scale version of the Wasp Major, though many design concessions will have to be made to ensure that it will be a running model. I will attempt to document the process of development, and as I am using a CAD program it should be easy for me to go back and make adjustments as required (provided I follow proper CAD procedures, something I often fail to do)

Again, if anyone sees anything questionable, has input, or any questions in general, please don't hesitate to jump in and help me. I apologize for this being a CAD work (for now!) and not a real machine, but some time down the road I will start another WIP when I have sufficient tools and skills to give the real thing a try.

Cheers,
- Ryan
I would really like to correspond with you on this project as I have a keen interest in the 4360 to an as a model. . I can give you an email address if you like just add request to this post

byron nelson
 

Bentwings

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Well, I promised (threatened?) that I would start a WIP for my probably long-running design process for a scale Pratt & Whitney R-4360.

For anyone curious, the R-4360 is considered the largest piston engine to ever go into production for airplanes. It was used on a variety of aircraft at and after the end of World War II, and while thousands were manufactured, most were scrapped when the military no longer needed them due to the introduction of the jet age. Few remain, and fewer still are still flying. Most are in museums as static displays, many were even cut away to show the interior workings.

In the past couple of years I gained a sort of passionate love for this 28 cylinder radial engine that my girlfriend is probably a little jealous of. I have done a lot of research on the engine, and am always doing more. I feel the best way to show this beast a proper respect is to try and develop a working scale model.

Countless design decisions will be forthcoming, and I welcome input from all corners of the forum on anything that sounds or looks questionable. While I intend to build this behemoth of a model, I currently have no shop, no machines, and very rusty skills. If something looks like it will be impossible to machine, please don't hesitate to speak up.

The full-scale R-4360 sports some utterly astounding statistics. 4,363 cubic inches of displacement, 28 cylinders arranged in 4 rows of 7 cylinders, with 4 magnetos driving them. It 'sipped' upwards of 100 gallons of 108 octane fuel an hour (try that with today's prices!) all metered from a single pressure carburetor. Each cylinder sported a 5.75 inch bore with a 6 inch stroke, giving a 6.7:1 compression ratio and fired two spark plugs to ensure the cavernous compression chamber ignited evenly and fully. Intake ports were mounted on the top of the chamber, with exhaust out the side (analysis done since have suggested it would have been far more efficient to switch these two, and would have solved some of the intricate heat problems they had). This entire machine was air-cooled, requiring an astonishing amount of air to flow through the cooling fins, and indeed a lot of designs were tried to get the optimal cooling. The 3000-3500 horses were caged in a package that measured 55 inches in diameter and 96.5 inches long, weighing 3,870 pounds dry.

In military applications, the Wasp Major as it was known, was used in a variety of aircraft, from experimental to production. A list of aircraft that used this engine can be found on the following wikipedia article: Pratt & Whitney R-4360 Wasp Major - Wikipedia

Perhaps most notably was the F2G "Super" Corsair (Not the much more popular F4U Corsair, but very similar). Postwar, Several F2G's were converted into racers that dominated the air races until a tragic accident shut down the Unlimited Class until the 1960's. Since then, one Super Corsair named the Dreadnought took away numerous finishes, until it crashed in the mid 1980's. I believe Dreadnought is nearing rebuild, but that information may be inaccurate.

My goals with this design are to create a 1/6th scale version of the Wasp Major, though many design concessions will have to be made to ensure that it will be a running model. I will attempt to document the process of development, and as I am using a CAD program it should be easy for me to go back and make adjustments as required (provided I follow proper CAD procedures, something I often fail to do)

Again, if anyone sees anything questionable, has input, or any questions in general, please don't hesitate to jump in and help me. I apologize for this being a CAD work (for now!) and not a real machine, but some time down the road I will start another WIP when I have sufficient tools and skills to give the real thing a try.

Cheers,
- Ryan
I to have a Pashto also interest intert in this engine. I would enjoy trading email and thoughts. Post if you would like to participate. I’ll try and watch here daily
byron
 
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