I think one of the main reasons the Jug was so big was to accommodate that huge radial engine. As has been mentioned before, when they first arrived in Australia after seeing one person exit the aircraft an Aussie remarked "Where's the rest of the crew"? My Uncle said he always felt safe while flying the thunderbolt. Well, as 'safe' as one could when tracers were zooming passed the cockpit. He also said the 'Jug" was a more stable platform at strafing than the P-51.
As far as losses go, does anyone have any stats on how many of the ~3500 losses were combat related and how many were due to accidents etc.? One of the negatives about the "jug" was it was hard and expensive to maintain. That's why the USAAF (USAF?) dropped the P-47 in 1947 and kept the Mustang until after the Korean War. Another reason it was so heavy was its turbo-supercharger system and also the extra two 50s + ammo.
On Page 328 (pdf page) of this document http://www.afhso.af.mil/shared/media/document/AFD-110331-045.pdf it lists 1,125 P-47 wrecked in the Continental US due to accidents. That's over 1/3 of the losses right there. Looking at http://www.tuskegee.edu/Uploads/files/About%20US/Airmen/332dFighterGroupMissingCrew.pdf for P-47 the listed cause of losses is unkown 4, failure 4 not sure how much combat they saw during that period though. If I'm reading it right this page http://www.taphilo.com/history/8thaf/8aflosses.shtml states 1,043 P-47 were lost in Europe. Which leaves about 1,000 lost elsewhere.
Harolds, a little help please. I vaguely recall the P 47 exhaust was routed to behind the pilot and through a turbocharger which compressed new clean air. That air would have to ne piped back to the intake of the engine upfront or did it drive a shaft to a compressor mounted upfront ? Either is complicated given the distance from the engine from the turbo. Now they refer to it as a turbosupercharger . Turbosupercharger implies that both a turbocharger and a supercharger are used. They have existed for sometime and VW will have one on the road soon. Does the Wright Double Wasp 2800 on the P 47 also have a supercharger on it ? Or is this a nomenclature use calling a turbocharger a turbosupercharger which by definition it is not ? In a turbosupercharger the compressed air from the turbocharger is feed into the intake of the supercharger which in turn compresses it more . A supercharger is driven directly off the driveshaft of the engine using horse power produced by the engine to compress the incoming air which in turn allows the engine to produce more horsepower that the supercharger uses. WHEW ! This is a double boast application with the advantage of instant power from the supercharger plus free or nearing free horsepower from the somewhat lagging turbo. Two boast systems = power= complication. Or is the "JUG" simply a turbocharger engine albeit a complicated one. I promise I am not trying to be verbose but I really want to know did the P 47 have a turbocharger or that and a supercharger as turbosupercharger implies. Perhaps the terms have changed but this is not new useage. I have Googled all of this and cannot find a clear answer and I truly would like to know. While we are at it did the Corsair using the same engine use the same "boast" system ? In my time Superchargers and turbochargers were a means to more power bow both are being developed to a means to more fuel efficiency. Gaines
Contemporary usage of turbosupercharger related to the P-47 was a turbine driven supercharger, or shortened to turbocharger. It was not a hybrid combining a mechanical supercharger.
Thanks guys, exactly what I wanted to know. I looked for images under drawings, sections and that one is perfect. It is as I expected, what is now called a turbocharger. Turbosupercharger must have been the term used at that time. A few existed in the 30's but were experimental and interesting that lots of working going on it the turbosupercharger dual units now.....in autos. The Jug looks complicated enough !!! Gaines
Well they may be complex but certainly tough! There are numerous stories about losing a cylinder or two and retuning on the remaining 16 0r 17. it would seem the connecting rod would stop the engine but I guess they could slide up and down in the cylinder base opening or just break off. Good to have 18 to start with !
Hi Mccoffee When you say hybrid in this context do you mean a compound turbo like used on the Wrights in the B-29 in which the turbo was mechancially linked to the engine? I agree that the P-47 did not use such a set up but I thought all R-2800s had an internal mechanical supercharger and that the exhaust driven turbo in the P-47 fed air into it. The P-47 definately had a supercharger control in the cockpit and I didn't think those were applicable to turbochargers. In other words, the pilot dosen't set boost level in a turbo like with a mechanical supercharger. Here is a picture of the supercharger on an R-2800. I know most R-2800s had them and I thought they all did. I've been wrong before though and will be again. https://www.flickr.com/photos/jacofoto/5006400648/ EDIT: Opps, I didn't notice Gaine's post #24. That is the way I always thought the P-47 worked except for your use of the term 'turbosupercharger' In the P-47, the turbochanger feeds the supercharger. To cloud it even more though, many people use the term 'turbosupercharger' to refer to an exhaust driven turbocharger, especially in modern automobile applications. In a turbosupercharger the compressed air from the turbocharger is feed into the intake of the supercharger which in turn compresses it more . A supercharger is driven directly off the driveshaft of the engine using horse power produced by the engine to compress the incoming air which in turn allows the engine to produce more horsepower that the supercharger uses. WHEW ! Another little tidbit is that mechanical superchargers use horsepower. I saw one datasheet that said the supercharger in a Merlin at full boil took 600 HP to spin it although there was still a big net increase. The D0 217P used a seperate DB603 engine in the fuselage just to power a large supercharger to feed the wing mounted engines.
The turbocharger mechanism was behind the pilot. It seems to me that if bounced from behind it would be very susceptible to being damaged or put out of action. A couple of 13mm rounds would probably do the trick. At say 20-25 thousand feet that would mean a big drop in performance right at the time it would be needed the most.
Dave, I don't believe the R-2800-21 and -63 used in the Jug's had the mechanical supercharger section. The diagram in post #26 shows the ducting leading directly to the carburetor. However, I would certainly defer if someone has more definitive information.
I recall reading an incident related by Navy great David McCampbell who flew the F6F powered by the R-2800. McCampbell landed aboard the Essex and looked back at his wingman's plane who landed behind him. One of the cylinders had been blown partially off the wingman's engine and McCampbell could see the piston going up and down. The wingman was giving the plane captain a thumbs up signifying he thought the aircraft was "up" for further flight - not knowing the cylinder was gone.
Wit regards to the R-2800-21. My understanding is that both of you, are in a sense correct. The Turbo fed air into the carburetor, the air then traveled from the carb to the internal single-stage supercharger, finally, it went from the supercharger to the cylinders.
The supercharger control on the P-47's throttle quadrant, according to the pilot's manual, controlled the amount of air going to the turbo. The book procedure was to advance the throttle all the way and leave it there, and then use the turbine supercharger control to adjust airspeed. This was done to prevent overspeeding and damaging the turbine(occurs when the throttle is set lower than the turbine supercharger). Later model of the P-47 would have a connecting linkage that allowed all throttle controls to be moved as one.
Very interesting thread. In my day superchargers were direct drive compressors, and turbochargers were turbines (hence "turbo") an impeller driven by exhaust gasses that in turn drove another impeller to compress air. Both air compressors , driven drives. Turbosuperchargers existed but largely experimental. I agree the terminology was a little lose but perhaps different usage by different groups. I was genuinely curious to find out if the P 47 or similar radials used both. Very interesting is the current development of both being used on sub two liter engines for efficiency. Thanks guys for all the information. In the early 50's I was drawing sections through flatheads, OHV, SOHC and DOC engines to figure out how they worked. My mentors were two car mechanics , both WW2 vets, one US and one RAF, the RAF guy came over with the MG, Jag, Triumph , Austin Healy influx. I should have been an ME ! Gaines
Dave, a whole new can of worms ! LOL, I had thought about turbochargers producing some degree of back pressure but like the supercharger was overcome by even more horsepower produced. Good info here. I did not know about a mechanically connected turbine, in most turbochargers the driven turbine usefully directly drove a second turbine to compress air...an indirect feedback. Since turbochargers have a turbine within the exhaust stream and it often, nowadays, spins in excess of 100,000 rpm the bearings must be fantastically well sealed and the shaft must penetrate the exhaust system container without letting exhaust escape those seals are also critical. The Turbo compound has the same problem. I have to wonder about what those seals and bearings are made of not to immediately fail. Of course turbos has drastically improved over time but date back to about 1905 !! The mention of F 1 cars for 2014 is most interesting as I follow F 1. Mercedes seems to have the current upper hand. Hard to imagine a 1.6 L V 6 compound turbo making that kind of power. Most of the V 12's of WW2 were in the 1700 cu in range. Warfare is terrible but certainly produces advances in technology. . That means a 90 cu in F 1 car makes about half the power a V 12 1700 cu in L aircraft engine in WW2.. I would love to see a longitudinal section of a 2800 Wright double Wasp in a P 47 to see how it all interacts.. Many thanks, Gaines
One thing to keep in mind when comparing automotive engines with aircraft engines is the conditions underwhich they are designed to operate. The 4.7 liter (287 cubic inches) engine in my vehicle is rated at 300 HP. However, cruising at 70 mph requires it to produce an average in the 25-30 HP range - 10% or less of rated power. A modern general aviation engine producing 300 HP will be in the 500+ cubic inch range. This engine is designed to produce full rated power for takeoffs and climbs, and to continuously produce 75% of rated power during cruise. And it is designed to do so for a time between overhaul (TBO) of 1800 hours or so. The F1 engine is certainly a marvel of technology, but they are overhauled what, every 5 hours or so, maybe less? Top Fuel dragster engines produce 4000+ HP but are torn down after every run, and sometimes during their 5 second TBO, come apart in spectacular fashion.
