I'll have a look a over the weekend, but those spring to mind as what I have. I'll PM you if I have anything more.
I'll have a look a over the weekend, but those spring to mind as what I have. I'll PM you if I have anything more.
Thanks calypsos.. Very much appreciated..
I just placed a couple more books in the documentation directory on the teamspeak file browser.. The book on the P-61 Black Widow Units contains some very nicely done drawings of the nose art for "borrowed Tim", Jukin Judy, Moon Happy, the Virgin Widow, and others..
I Found this pdf on Frank Walker, the creater/main engineer behind the Pratt and Whitney R 2800. Normally, i just gloss over these things as biographical fluff, but not this time.. this time, the PDF puts down in words exactly what they were able to do with the little R2800.. prepare to be blown away.. The pdf in whole can be accessed at http://www.enginehistory.org/Frank%20WalkerWeb1.pdf
""His first job was in single-cylinder development of the forged cylinder head of the R-
2800 “C” series engines. Rather than being cast in place as was the usual practice,
cooling fins for this cylinder were made by gangs of saws that cut grooves into the
forging. After initial problems with cracked fins, loose spark plug thread inserts, and
leaky rocker box cover leaks, the new cylinder head entered service and remained
essentially unchanged through the remainder of R-2800 production."
""“Parkins struck terror in the hearts of test engineers, and some of the guys even
claimed he ate nails for lunch”, remembers Frank. “He made me go to Ford River
Rouge plant over the Fourth of July in 1942 because they were having trouble
getting some of their “B” engines to produce rated power1. When I arrived, I met with
a team and asked them to pull a production engine at random and install it in the test
cell. I was really impressed, because they had it ready to run in about half an hour.
Back at Pratt & Whitney, it took us half a day to do the same thing. We ran the
engine, and it produced 1950 HP.” “Pull another”, said Frank. It produced 2050 HP.
Not wanting to give the Ford guys a chance to find out just how new he was to the
engine business, Frank figured he had better do something to get out of there as fast
as he could. “Gentlemen”, he said, “what we see here is the normal power output
spread of engines in production. You don’t have a problem”. ”Let’s try another”, said
a Ford Engineer. “No need”, said Frank. “I’ve seen all I need to see”.""
""“Test Engineers usually worked exclusively on one project and rarely had any formal
connection to the projects of their peers. There was some cross-pollination in
lunchrooms and around water fountains. Once, over lunch, Frank’s friend and fellow
Test Engineer, Elton Sceggel, was having a bad day. He was working on the new
“E” model of the R-2800 which featured two large superchargers, one on either side
of the rear accessory case. These were driven through variable-speed hydraulic fluid
couplings rather than the usual clutch and two-speed gear train. It was the first and
only Pratt & Whitney engine to feature supercharger impellers that were mirror
images of one another. “I don’t understand it, Frank”, said Sceggel. “I have been
testing all morning and can’t even get 1000 HP out of this pig. Manifold pressure is
low, and the superchargers are making a devil of a racket”. Frank stared off into the
distance. “Scege”, he said, “is there any chance the impellers are switched?” “No
way”, replied Sceggel. By then, lunch break was over and the two engineers went
their separate ways. Later they passed in the hall. “Frank!”, cried Sceggel, “you were
right! We reversed the supercharger impellers and the thing ran just fine!”""
In early 1943, word came down from the front office that a means must be found to
get additional power from existing engines without redesigning either the engine or
airplane it was in. While Pratt & Whitney was working around the clock to complete
the 3000HP R-4360, it was still years away and could not be fitted into existing
The shortest path to more power is always more manifold pressure. Since the P-47
had a turbo-supercharger which could produce surplus manifold pressure, it seemed
a good candidate for more power. The rub was that with the additional compression
of the inlet air came heating of the inlet charge which resulted in power-limiting detonation. With the 130 PN2 fuel than available, Pratt & Whitney was already
getting all the power that was possible with the R-2800. Someone in the front office
suggested that water injection be tried. Perry Pratt was the Project Engineer.
Frank acquired a stock R-2800 “B” engine, serial number 5275, directly from the
production line. The only modification to the engine was a longer hollow bolt to
accommodate a second banjo fitting that supplied water to the fuel inlet of the
supercharger. Frank performed all of the initial water injection calibration by
manually adjusting the throttle, supercharger, propeller, and water injection settings.
Once the behavior of the water-injected engine was understood, Frank presented
data to the carburetor group which, under the direction Dick Coar, designed and
developed a water injection regulator and the associated carburetor modifications.
Frank got 2150 HP the first night. This was up from the 2000 hp the engine normally
produced and was the sole result of being able to use a leaner mixture at take-off
power. Until then, the engine had to be run very rich at take-off power to prevent
detonation, actually using fuel to cool the engine. It was running so rich in fact, that it
was producing less than ideal power. In later experiments, manifold pressure was
increased to simulate the output of the turbo-supercharger, and horsepower
Ultimately, the maximum power achieved on the “B” series was 2800 HP at 2700
RPM. Maximum power ever achieved on the “C” series was 3800 HP at 2800 RPM.
The maximum manifold pressure ever recorded was a staggering 150 inches of
mercury (inHg)! This was up from dramatically from the 49-inHg maximum manifold
pressure originally allowed in the R-2800 “A” series of engines ""
and there you have it.. 150 inches of manifold pressure.. How they got to 3800 hp is further down the page, and is extremely humorous since it was half prank done to piss off the 4360 ( wasp major ) engineers who had a habit of snubbing their noses at the "little" R 2800.. our P-61B uses the B series. Heres the problem.
According to AFSD oir little engine is producing well over 4000 horsepower. Itook all day and all night saturday to address that exact issue.. With the SDK open alongside AAM and Aired and Robert on teamspeak, i went through it number by number. At first, i played with the turbocharger.. Just doing that, i was able to bring the horsepower reported by afsd down to 2212, which was only 13 horsepower off from the documented 2250 hp.. only problem was, the plane wouldnt fly over 200 mph.. Theres certain numbers in an airfile that are sacrosanct. induced drag is one of them, so changing that at this point in the game was out ( besides it only really comes into play during a turn ) and and over all drag was already at a minimum.. Ptop diameter, moi and min/max pitch are documented and unchangeable except within limits. Changing the prop time constant didnt improve much either, and prop efficiency values had already been maxed out.. It became a joke.. Since the real P-61b didnt have a turbocharger, i deleted the entire section and whata ya know, we were able to get back up to 275 mph with just the supercharger in there. Of course, AFSD was reporting 3320 hp. I saved my work, copied the entire folder and began working on the P-61C as a test bed for the B model.
At 11PM, I broke the 400 mph barrier on the C model.. AFSD was reporting well over 4000 hp at the shaft ( shaft horse power ), but 2781 hp at the prop (Brake ( or pulling ) horse power ).
Since the engines ratings are based on brake horse power I copied the settings over toothe P-61B and took it for a flight.. At midnight, i hit 360 mph in the B model without WEP, and with wep, was able to push it to 410 mph ( 11 mph short of red line according to Johnny Meyers ).
AFSD remains a point of contention. its been very useful in determining fuel usage but i have to take a 12 hour flight to test that, and other data was extremely useful in tuning the engine. But the number of debates that have occurred in this thread and other places here, regarding its readuts has left me with a severe bad taste in my mouth.. The gauges are normal and unmodified, and the readouts from them are exact and according to Frank Walker " Within normal production" variances. we're seeing over 3000 shaft horsepower at full throttle, but onlu 117 at idle which i'm more than happy with..
there's still a lot here for me to explore with the plane over all.. Enough reading material to keep me occupied for months and a mystery between what some pilots report and what others report.. Flown properly, the P-61 wasnt just a good fighter, in fact, some of its pilots claim its the best ( nd they flew single engined thuds and other planes before this ). it was a great fighter. Now to unravel why the differences in pilot reports..
Good stuff, Pam. Love engineers!
"Is there any way the supercharger impellers could be backwards?"
"What? No way! Err, I mean, maybe..."
:::LOL::: exactly the same thought i had.. Soooo, while i was doing a fuel burn check from sfo to ord I started experimenting with exact ratios.. at 1.77:1 the horspower repoted dropped to 3100 and we got to 285 mph. At 20:9 we were doing well over 500 mph and became uncontrollable. At 9:20 we became controllable but couldnt get over 310 mph, but at 2.24:1 (20/9 ) we were able to get back up to 355 mph At 21000 feet with 45 inches of mp. AFSD was still reporting 3100 hp, but, that combined with the reality that afsd was reporting that i'd run out of gas at 2500 miles, and i hadnt burned a drop by the time i reached denver pretty much caused me to write afsd as a lost cause on my particular machine.. however, it did help me to trouble shoot one thing, and my gear reduction entry in the config file now reads "gear_reduction_ratio=2.24:1"..Oddly, That works.. now its back to the drawung board on fuel burn..
Pam said " Now to unravel why the differences in pilot reports.. "
How about putting it to Franks statement "" Within normal production" variances."
As an auto mechanic working at the dealership, I often ran into this. Two IDENTICAL vehicles, built within hours of each other, were NOT perfectly identical in performance. Same goes for anything else, including aircraft.
I'd love to do that modelr and in most instances i can, but, i've got a few that beg to be answered. First, theres Johnny Meyers claims about the P-61
s abilitys, and the statements from the pilots that rode with him, backing those statements up. Statements like the planes ability to outmaneuver an F4F with one englen out and the prop feathered.. Other statements like its ability to outmaneuver any fighter period.. Documentation from several pilots from the the 421 NFS about the planes superiority over the P-38 oncluding speed, and thene there was earl Barnes ( i think thats his last name ) a General, who hated the P-61 and did such a turn around he chose to use one for his personal plane.. What made him want to do that?? obviously the P-61 proved itself beyond his expectations to the point of delight. His plane was the only bare metal P-61 in the war, and more, it was the only P-61 with the ADF mounted on the bottom.
Now, heres the thing ( and the part that mkes it very difficult ). I was in the Military in viet nam.. my issued weapon was an M-14 ( m1-a1 today )I hated that thing in ways tht would make the devil blush. It was for me, the worst pile of ****e ever created. I tossed it and bought myself an M-1 Garand.. Yet, today, there are countless numbers of people who think that rufle is the best thing that ever happened. The regularly score major scores at shooting matches with them. So is the weapon good or bad?? The same goes for the P-61.. in the military, usually if someone likes something they arent too loud about it, but given one small percieved imperfection oh my god the noise that can be heard.. With the P-61 we have as many positive comments as we do negative, and i can only believe that if there's positive comments, then the plane was indeed very special, but thats balanced against those that didnt want the plane to begin with. They wanted the mosquito, and they almost got it, but the P-61 outflew even it. The P-61s record shows it taking down everything from Japanese betty's to butcher birds, and some of those became very real dogfights..
It's kind of funny. I watched this show called Restrepo last night. Ot was about the guys at OP Restrepo in afghanistan. generally, when you watch a show about something war related, you end up with a lot of propaganda about heroics and glory and all that happy hprse ****. But Restrepo was simply reality as it was lived. It'll take me a while to process it, but truth told, those boys didnt seem so much different than we were in our war. i cant imagine that we were so much different than the guys in world war two.. So these guys, past and future are my brothers and family ( of sorts ) just like you all here have become my family, and its important that i unravel the truth behind this plane, for them and the people of this community.
I know that at the end of the war, the only prop plane that could outrun this thing, was the twin mustang with its 584 mph top end, and i know that the main reason the P-61 project ended was because the pentagon was worried that you couldnt slow the plane down fast enough to get in behind an enemy plane.. I also know that Johnny Meyers was able to take off in 900 feet with it, raise the gear, turn around and make a pass over the field with it at over 420 mph, do a few loops and a chandelle ( on one engine ) then land ( still on one engine ) in less than a thousand feet..
These are all pointers to how this plane actually flew, and if i'm going to do this plane justice, I have to make it right and make it true to the real plane as much as i can. Horsepower i dont worry about. Why?/ because theres no program out there that will give me those numbers correctly. AFSd failed miserably and has left me having to go back and recalculate the fuel consumption ( not to mention causing me to waste a day and an entire flight model tryong to get those numbers spot on ). It was the only program out there that i know of.. All i have is what the pilots have said. So now I somehow have to take their conjecture and turn them into numbers.. Its kinda fun and ya gotta admit, i'm gaining one hell of an insight into history..
I get it to fly just fine on 2000 hp, with correct speeds. If it doesn't drag is too high. Check the CDO figure in the primary aerodynamics tab. Also check the mach drag table, one should certainly not have any mach drag at all on takeoff.... and almost none till M 0.5 or so.
Very familiar with the PW test cell results and development of the "C" engine. However do not confuse the very high HP values obtained in a test cell with anything you could do in a production military airplane. Aircraft have issues with cooling of both cylinders and oil, unfavorable air temperatures, imperfect, or not optimal fuel supplies, limited quantities of Water Methanol and on and on. Development of very high MP's will lead to detonation in very short order, especially with turbocharged engines if a good intercooler is not operating, with favorable cool outside air temperatures. The P-47 was much happier at high power settings in the cool skies of Europe in the winter... than say in the Pacific. Test cell engines don't have to deal with any of these things if that is not the area being explored.
My friends who still fly R2800 powered aircraft on a daily basis still puke a lot of engines, even with a great deal of opertional experience and sophisticated engine anaylizers.
I hear ya Tom.. And yeah. not giving much creedence to the test cell results at all, but i still find it pretty amazing what they were able to accomplish on the type C engine.. The B type, which is what's in our plane, maxed out at 2800 hp. our engine is only supposed to be 2250 hp. perhaps your machine is set up differently than mine, allowing AFSD to function correctly, but, when AFSD reported that i would run out of gas at 2000 miles and after 1500 miles i hadnt used a drop, it was all over between that program and i.. i simply cannot trust it.. The specific 2250 hp I think we're using, is specific to the p-61B. it had upgraded engines over the P-61A which used the 2000 hp engines you mention..
Perhaps if someone develops a program that gets its information directly from simconnect instead of going through fsuipc first, i'll give that a try, but until then, i'm afraid i'll just have to stick with the numbers reported on the panel by the instruments.. In the end, those are the numbers that people will be reading, and the ones they see, so in a way, its the panel readouts that are most important any way..
Last night, i slugged an engine accidently.. I was landing, and as i came in on approach a stupid tubeliner pulls out onto the runway for takeoff.. I was only doing 110 at the time so i throttled it to get around him.. Bad move.. the engine died, the plane rolled over a hundred feet off the ground, and it was all over then.. Plowed a whole new garden for the airport right there.. it took me by surprise. I dont have engine damage turned on and it still choked..
N2056 took the plane up a couple nights ago. As you know, he flies the thorp with his father a lot in real life, and usually doesnt fly any sim aircraft as he enjoys building them more.. :;chuckles:; took him fourty minutes before he stopped flying .. I'm not going to worry about numbers we cant see. i think we're pretty spot on as is. The RPMs can even run away from you in level flight if you dont manage them correctly. What concerns me now, is sifting through the details and stories and making the plane reflect as best i can, exactly what the men who flew her experienced.. hell, if i could, for every livery that Jankees and Don put out, I'd modify the flight model to match that exact airplane.. But that may be more than i can realistically hope for..
Some of the Reno racers (with Merlins) do run around 150" or so, at something like 3500 RPM. Quite special fuels, many special high strength parts etc built just for those racers.
The R 3350 was used for the very high priority B29 and several other aircraft that might have used this powerplant just lost out on the priority game. The R4360 was installed in an experimental F4U-1 test bed in 1943. Later, really too late for the war and only produced in 10 samples was the (Corsair) F2G, an example which is at the Museum of Flight in Seattle.
The R2800 owed a lot of it's sucess and longevity to the KISS principle. Sophisticated to be effective, simple enough to maintain and have a good service life with reliability.
those guys at reno really impress me to no end. rare bear is awesme, as is Strega, but everyone that flys there is simply amazing to me.. they're machines are incredible.. but for racing here at SOH, i have to keep the C stock.. its understandable, as theres a few of us here that could easuly build a plane that could do mach 15 in a hearbeat and still be maneuverable.. but as you know, races arent won just with speed alone, and theres a lot of pilots who are better than I'll ever be.. ..
Oh and yeahhh, the b-29 got all those turrets you dont see on the widows.. its understandable it'd take the engines as well. I'd love to have seen what could have been done on those fighters with those engines.. It would have been awesome..
yes i know i cant spell half the time! Thank you kindly to those few who pointed that out
heheh.. i was thinking we create a mechanism linking it to the radar so that as we approach someone it automatically swings into firing position.. I dream big :;chuckles:;... ::LOL:; i could just see tht thing going nuts in the middle of an online flight with seven ot eight planes all around ::lol:;
technically, it should be controlled from the gunners seat, but since FS Host wont let more than one person in a plane, thats kind of a dead end..
ts sad kinda. because of the way this plane was built and laidout, and the equipment it used onboard, the technology we would have to use as modelers, is more advanced than almost anything else i've run across yet. from the gun turrets to the radar. its tech that just hasnt been created for fsx yet. one radar screen shows vertical deflection with blips, the other radar screen shows lateral deflection with peaks on a sine wave,, the screen in the cockpit only shows vertical deflections.. No ones coded anything like that yet, and it would most likely be a big job. I gotta admit, my hopes for making that part of the plane, which was really its heart, are dropping fast.. There's just not that much interest from people for flying together online, which is the only place radar would have any benefit. with no interest in flying together, theres little need for guns.. No one would be interested in dog fighting.. I try not to think about that.. We go on..
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