Best Fighter III (1 Viewer)

Jabberwocky · Oct 25, 2005

wmaxt said:
Jabber,

Could I have your sources? I always like to back up what I have.

My sources give the L 414 @ 54in and 1,425hp, and the J 420 @ 54in and 1,425 both in METO throttle.

Jon,

Rember even if wasn't used much in the ETO, the use of differential throttle and rudder for max performance in a P-38.

The 480 dive limit is also altitude (density) dependant.

wmaxt

The source I used is Carlo Kopps article "Der Gabelschwanz Teufel" at the WW2 Aviation essay page http://home.att.net/~C.C.Jordan/index.html

The generally quoted figure is 420 mph for the J and 414 mph for the L. Both figures are for 54" hg and 1425 Millitary Power with the Allison V-1710-89/91 (F-17 engine) or 111/113 (F-30 engine). However, Allison rated the 111/113 up to 67" Hg with 100/130 octane fuel and 1725 War Emergency Power. The F-30 was essentially the same as the F-17 but with 2 differences 1. A more efficient carburettor and 2. A 12 weight crankshaft instead of a 6 weight crankshaft. This allowed increases in manifold and more importantly, a new propellor overspeed rating of 3200 rpm, up from the old 3000.

While it was never 'rubberstamped' in the manuals, there was a field order in late 1943 that allowed an increase in manuals from 60" and 1600 hp at WEP to 66" and 1725 hp. It seems that It was only available for the P-38L-5 production blocks, which were delivered around October 1944.

Lockheed performed dynamic output testing on 46 V-1710- F-30
engines in May of 1944. Power output varied from 1,737 hp to 1,765 hp at 60 in. Hg, 3,170-3,215 rpm. Four engines were subjected to boost pressures of 66 in. Hg. @ 3,200 RPM and produced the following output:
1,812 hp
1,833 hp
1,798 hp
1,807 hp

EDIT.

Did a little more digging and it seems that the numbers of P-38s that ran on 66" would of been fairly low; one fighter group in the ETO (474th) and a couple in the PTO. The most common figure would of been for the 1600 hp and 60" rating, BUT the 1725 hp rating was used in combat. It would probably be representative of a P-38L-5-LO in the final months of the war.

Erich · Oct 25, 2005

sorry but the title is all wrong so would the data be ? Fork tailed devil was never used by any Luftwaffe vet.

two centos

lesofprimus · Oct 25, 2005

This is true...

JonJGoldberg · Oct 25, 2005

FLYBOYJ:
"In that case "Head Pressure" (No Pun) might be designed into the tank. This occurs when a pressure (either positive or negative depending on the design) is placed on the tank, the say way you might get gas released when you take the fuel tank off your car. This too will minimize sloshing in the tanks...."

Why doesn't sloshing stop in a soda bottle? Not trying to be smart... But I don't think head pressure stops sloshing. I think its a physics thing, you can not compress a fluid (but you can compress the 'air' trapped within a fluid).

FLYBOYJ:
"The design and placement of bladder tanks will play a part in this as well. When you saw the bladders, did you look inside? Sometimes even the bladders have baffles within them, only visible when the bladder is cut in 2."

Did they use bladder tanks in small aircraft in WW2? Not an area I know a whole lot about; practically nothing aside what I wrote to syscom3; But now I'm curious. Seems that this system may cause more problems than it solves, looking at it from my point of view (an idiot to be sure); a bladder, I think would require some pressurization in order to be sure we didn't create a hiding spot, or to be sure we got every drop... Mind you, I'm not talking about the bladder between outer and inner walls of the tank (Self Sealing bladder) but a bladder holding fuel is what I think you are saying.

Jabberwocky · Oct 25, 2005

Erich said:
sorry but the title is all wrong so would the data be ? Fork tailed devil was never used by any Luftwaffe vet.

two centos

I always understood it to be a Heer saying, not a LuftWaffe one. Probably something to do with the amount of G/A sorties that the P-38 did in Normandy and its unique shilouette when viewed from below.

FLYBOYJ · Oct 25, 2005

JonJGoldberg said:
FLYBOYJ:
"In that case "Head Pressure" (No Pun) might be designed into the tank. This occurs when a pressure (either positive or negative depending on the design) is placed on the tank, the say way you might get gas released when you take the fuel tank off your car. This too will minimize sloshing in the tanks...."

Why doesn't sloshing stop in a soda bottle? Not trying to be smart... But I don't think head pressure stops sloshing. I think its a physics thing, you can not compress a fluid (but you can compress the 'air' trapped within a fluid).

Because soda (basically water) weighs more than Av Gas - it possesses a characteristic that makes it slosh more.

AV Gas actually has a characteristic (I can't remember the name) that keeps it somewhat contained if pressurized. I think it's because of it's petroleum base. It tends to "creep" or adhere to the sides of a container. It's this same characteristic (god I wish I remembered the name) that mandates the float level of carburetor to be taken in the middle of the float instead of the sides - sounds crazy, but I remember this from A&P school.....

JonJGoldberg said:
FLYBOYJ:
"The design and placement of bladder tanks will play a part in this as well. When you saw the bladders, did you look inside? Sometimes even the bladders have baffles within them, only visible when the bladder is cut in 2."

Did they use bladder tanks in small aircraft in WW2? Not an area I know a whole lot about; practically nothing aside what I wrote to syscom3; But now I'm curious. Seems that this system may cause more problems than it solves, looking at it from my point of view (an idiot to be sure); a bladder, I think would require some pressurization in order to be sure we didn't create a hiding spot, or to be sure we got every drop... Mind you, I'm not talking about the bladder between outer and inner walls of the tank (Self Sealing bladder) but a bladder holding fuel is what I think you are saying.

Bladders weren't used in small aircraft (L-19s L-5s, etc.). A plain rubber bladder were mainly found in transport aircraft, self sealing bladders were found in combat aircraft - again you're correct about the pressurization, it was common to have boost pumps providing positive pressure so the fuel doesn't "Hide." Boost pumps would be turned on during take offs and landings, emergencies and I would assume during combat - you would want to be assured there is a positive displacement of fuel going to the engine....

JonJGoldberg · Oct 26, 2005

FLYBOYJ:
"Because soda (basically water) weighs more than Av Gas..."

I do not think weight has anything to do with compressing a fluid; however with regard to mass, I can see that may cause more slosh, once started.

FLYBOYJ:
"AV Gas actually has a characteristic (I can't remember the name) that keeps it somewhat contained if pressurized..."

Again, its a fluid... But the characteristic you describe is called 'skin effect', with regard to the surface tension of a fluid at the layer of contact with another substance, or dissimilar fluid; or 'viscosity' maybe, the ability of a fluid to flow, or creep.

Anyway the only way this may work, in my head, and explain why syscom3 saw nothing in the tank he viewed, if the tank had a bladder can be seen in the gross pic attached... They probably discarded the bladders, or like myself before today, he did not recognize them for what they were in the clutter, as he did not know

JonJGoldberg · Oct 26, 2005

Wow... Based upon how many times I see you guys downloaded that fuel tank drawing of mine, as opposed to the chart, I'm hoping you don't about it as opposed to not caring. Since the ones who have seen it had very positive responses I'm re-posting it...

WW2 Fighter Operational Air to Air Performance Direct Comparison Table

An attempt to settle which fighter was best...

Sorry to all, in advance, who hate large posts...

syscom3 · Oct 26, 2005

Thats a nice chart.

I hope you can get more planes listed on it.

the lancaster kicks ass · Oct 26, 2005

it doesn't seem to work for me........

FLYBOYJ · Oct 26, 2005

JonJGoldberg said:
FLYBOYJ:
"Because soda (basically water) weighs more than Av Gas..."

I do not think weight has anything to do with compressing a fluid; however with regard to mass, I can see that may cause more slosh, once started.

FLYBOYJ:
"AV Gas actually has a characteristic (I can't remember the name) that keeps it somewhat contained if pressurized..."

Again, its a fluid... But the characteristic you describe is called 'skin effect', with regard to the surface tension of a fluid at the layer of contact with another substance, or dissimilar fluid; or 'viscosity' maybe, the ability of a fluid to flow, or creep.

Anyway the only way this may work, in my head, and explain why syscom3 saw nothing in the tank he viewed, if the tank had a bladder can be seen in the gross pic attached... They probably discarded the bladders, or like myself before today, he did not recognize them for what they were in the clutter, as he did not know

I think you're hitting the nail on the head - in addition I seen rubber blader fuel tanks with "baffels" built in - these are strips of rubber within the bladder attached side-to-side taking up the with of the tank.

wmaxt · Oct 27, 2005

[quote="Jabberwocky]

While it was never 'rubberstamped' in the manuals, there was a field order in late 1943 that allowed an increase in manuals from 60" and 1600 hp at WEP to 66" and 1725 hp. It seems that It was only available for the P-38L-5 production blocks, which were delivered around October 1944.

Lockheed performed dynamic output testing on 46 V-1710- F-30
engines in May of 1944. Power output varied from 1,737 hp to 1,765 hp at 60 in. Hg, 3,170-3,215 rpm. Four engines were subjected to boost pressures of 66 in. Hg. @ 3,200 RPM and produced the following output:
1,812 hp
1,833 hp
1,798 hp
1,807 hp

EDIT.

Did a little more digging and it seems that the numbers of P-38s that ran on 66" would of been fairly low; one fighter group in the ETO (474th) and a couple in the PTO. The most common figure would of been for the 1600 hp and 60" rating, BUT the 1725 hp rating was used in combat. It would probably be representative of a P-38L-5-LO in the final months of the war.[/quote]

Good info that expands on what I knew. That field order would have applied to the J models too.

1800+hp would give 450mph in a P-38J/L like it did in the K model!

Allison also ran the V-1710 to 2,300 hp and over 100". Here is an interesting site:
http://www.unlimitedexcitement.com/Miss US/Allison V1710 Engine.htm

L-5s were being sent out by September '44 and I'm sure the Crew chiefs "adjusted" things for their pilots.

wmaxt

Jabberwocky · Oct 27, 2005

wmaxt said:
Good info that expands on what I knew. That field order would have applied to the J models too.

1800+hp would give 450mph in a P-38J/L like it did in the K model!

Allison also ran the V-1710 to 2,300 hp and over 100". Here is an interesting site:
http://www.unlimitedexcitement.com/Miss US/Allison V1710 Engine.htm

L-5s were being sent out by September '44 and I'm sure the Crew chiefs "adjusted" things for their pilots.

wmaxt

I don't think that the F-17 engines that the P-38J were equipped with were able to be safely overbooseted to 66" Hg.

The F-30 had alterations to the carburettor and a 12 weight crankshaft, instead of a 6 weight crankshaft on the F-17s. The 6 weight wouldn't of been able to take the load of the higher RPMs. Ring's P.R.O. Docs page used to have some information on exactly this issue, but it seems to have gone off line.

IIRC the 12 weight crankshaft of the F-30 was actually under less stress at 1725 Hp, 66" Hg than the 6 weight crankshaft was at 1600 hp and 60" Hg. I know that fighter pilots and mechanics liked to 'tweak' their engnes for more performance (I have a pilots account of early razorback P-47s running at 90" or 100" Hg for 30 seconds in combat, instead of the normal 52" or 54" hg!), but it probably woulnd't have been widespread running the F-17s that high.

wmaxt · Oct 27, 2005

Jabberwocky said:
I don't think that the F-17 engines that the P-38J were equipped with were able to be safely overbooseted to 66" Hg.

The F-30 had alterations to the carburettor and a 12 weight crankshaft, instead of a 6 weight crankshaft on the F-17s. The 6 weight wouldn't of been able to take the load of the higher RPMs. Ring's P.R.O. Docs page used to have some information on exactly this issue, but it seems to have gone off line.

IIRC the 12 weight crankshaft of the F-30 was actually under less stress at 1725 Hp, 66" Hg than the 6 weight crankshaft was at 1600 hp and 60" Hg. I know that fighter pilots and mechanics liked to 'tweak' their engnes for more performance (I have a pilots account of early razorback P-47s running at 90" or 100" Hg for 30 seconds in combat, instead of the normal 52" or 54" hg!), but it probably woulnd't have been widespread running the F-17s that high.

Your probably right, they had some unique changes to the engines used with the K model too.

wmaxt

JonJGoldberg · Oct 28, 2005

the lancaster kicks ass:
"it doesn't seem to work for me........"

As in no hope, or fix this change that?

To All >>>
I'm posting Rev.2 of the chart. Added two more aircraft. Found and corrected some errors. Revised some things; tinkered a bit...Recieved/found new data, so I was able to change performance to "combat weight"

Help me make this work.

Thanks!!!

the lancaster kicks ass · Oct 28, 2005

it didn't work as in it didn't show when i clicked on the last link, and i got that chart, it's very impressive..........

DerAdlerIstGelandet · Oct 29, 2005

This is a really late post here but since I have been gone for a couple of weeks I will post it anyhow. There is a particular member that keeps saying that the numerical superiority of the P-51 should be thrown out the window because there were many Luftwaffe planes that were built just as numerous such as the 14000 Bf-109G's. The only comment I have to say to that is: If you really think that there were 14000 Bf-109G's in the air at the same time then you are more naive than I thought!

Second comment is that I have come to the understanding that some people here play these flight sim games and believe that they are "real fighter pilots" and believe everything that happens in these games especially when they are playing on "weakling" mode or invincible. Ive got news for you people Flight Sims are not "real" eneogh to base an opinion off of how an aircraft truely performs.

Yes they have gotten better over time and have become pretty acurate but dont take them as the bible of WW2 fighter combat.

FLYBOYJ · Oct 29, 2005

DerAdlerIstGelandet said:
Second comment is that I have come to the understanding that some people here play these flight sim games and believe that they are "real fighter pilots" and believe everything that happens in these games especially when they are playing on "weakling" mode or invincible. Ive got news for you people Flight Sims are not "real" eneogh to base an opinion off of how an aircraft truely performs.

Right on Adler! - I love to get students who tell me they played these sims - the first time I put em in a stall they Sh*t....

Some one posted here about flying sims and comparing them with the real thing - Put on a flight suit, G suit and Helmet dump a bucket of water over you, turn the room A/C down to 50F, Strap yourself in a big easy chair, get you're brother's 230 pound girfriend to sit on you when you pull Gs and if the room has a firplace, throw some .22 rounds in the fire to simulate small arms fire - Fly Safe!

DerAdlerIstGelandet · Nov 6, 2005

Okay this has now been split and there is a sepperate thread for Flight Sim argument. This one can not get back on topic.

JonJGoldberg · Nov 6, 2005

OK... I'm very glad the flight sim vs reality topic was split out. I think, however the knife was dull...

Look for the Spit-14, A6M5, F4U-1D to be added to the tables, and some more refinements, as I'll be working for the next few hours on the tables...

Feed Back Requested!!!

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