Hi I to am interested in the r4360 mine would be a bit smaller based on M. hogston’ r 280 I just got the book by White and have waded through it once and now looking more closely. How does the crankshaft link rod work. I’d really like a picture. 1000 words.LOL making the crankshaft will be a horrendous task for a small lathe, I think I’d carefully mill as much as possible maybe eve go so far as Th mak some kind of fixture for a rotary table. I doubt it would be strong enough to be built up. I have a good TIG welder but med issues has left me some eyesight issues. I have a good cad program so I I think I could model it. Maybe have it 3D printed for testing fit. I have some blower thoughts too. Not for real supercharging but more for good fuel atomization. I’ve seen two different carb on the r2800 model so I’m beginning to think an automotive AFR gage might be useful. I’ve used then on hot rods for years so have experience with them. They aren’t as expensive as they used to be. Keep in touch I don’t know how to add email short of direct and I’d rather not do that.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.
Second post on this. I’m also a Corsair fan having had a model in the family for over 60 years. Am I really that old. ....yes just watch me hobble down the street with my dog. I’ve been a fan of the r4360 for many years. My father in law flew them as well as dive bombers during the war. I built a 1/5 Th scale model Corsair that I flew for 13 years . Traveled all over flying at different fields. I won 5 scale events so it sported 5 kill markers .LOL. I always wanted to build a new one as an F2G but just never got around to it’ll the cowl is about 5” longer so the motor could be moved ahead to help balance it plus get rid of a couple pounds of weight. I did get to see the remaining racer one at Osgosh one year. Impressive. The r2800 model mother is a huge project. It’s going to require all of my machine shop skills plus design for the 4360 if I decide to go that way.Ryan,
I have been reading this thread from the beginning and would like to make a comment or two. First, although I applaud your desire to build this thing you have no idea what is involved. Reading posts by other fellows who have built single row radials will give you an idea of the work involved in producing such and engine. Now multiply that by 28 and even for machinists with years of experience it would become a daunting task.
Having designed several engines in my time I can tell you that there is much more to it than coming up with numbers. There's so many problems to be solved when miniaturizing that these issues alone can seem sometimes unsolvable.
The second part of my review is that of the actual machining. As you have found out by your initial postings about the gear mountings and how to split or not split them, for someone as you say with 'rusty skills' this should not be taken lightly.
I have somewhere upwards of 2500 hours in producing my V-8 engine and I would think that Steve has well over 1000 in just one of his so to build something like this my biggest concern would be the dedication to see it through.
You asked for any and all suggestions when you first posted and my advice to you would be, if you really enjoy aircraft radial engines why not design your own 5 or 7 cylinder engine? To design and build even one of these would be a great accomplishment.
Just my two cents worth.
Bentwings,Maybe have it 3D printed for testing fit.
I’m well aware. Of printed part fits. The resin is better buy far more expensive. It was always nice to have something you could hold in your had when debating what to do next.Bentwings,
Just a heads-up (which you may already know, in which case my apologies!) - what is usually meant by "3d printing" (fused filament) can be quite good in terms of hitting size, especially for external features (not so much for internal holes unless one does some careful tweaking. However, "quite good" is not in the realm of machinist precision, so this type of 3d print is not likely to be good enough to test the fit. You might get sufficient precision from a resin-based process - I don't know, since I've not used that type of printer.
Again, apologies if I am telling you things you already know!