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jeffmorgan_947
07-01-2010, 09:57 PM
Hi All. I have never had a lot to do with the P38,so I thought I would give it a go! downloaded "American Ace of Aces" based on the great Richard Ira Bong's experiences during the New Guinea/Borneo/Philipine campaign.At the moment I'm flying IL2/46 with Ult@pack v2.i so everything sounds,feels,and looks great!.

Although the P38 is a very nice plane to fly,I find that its response and handling in a dog fight with Japanese KI 43's is like a small truck.**** Bong I am sure would not agree? so to all you P38 jockeys whats the secret? Cheers JM

Sillius_Sodus
07-01-2010, 10:47 PM
Stay fast (300mph+) and the Ki-43's can't touch you. If you can shoot and hit at 200m-300m, you'll do fine.

Have fun, it's a great campaign.

AndyJWest
07-01-2010, 10:51 PM
Pilot Training Manual for the P-38 Lightning (http://aafcollection.info/items/detail.php?key=152&pkg=ls!title!!152!1!title!up!100)
You'll never be able to dogfight with a Ki 43. So don't - come in fast, fill him with holes, then get the hell out.

Against less agile opponents, it is possible to use combat flaps etc to counteract some of the inherent limitation of the P-38, but you'll never win in a turning fight, so don't try...

WTE_Galway
07-02-2010, 02:20 AM
Interview with Joe Foss USMC, MoH




THE P-38

Q. What was your impression of the P-38's?

A. The P-38 is really a good plane as an interceptor, above 20,000 feet. If you get notice that a bogey is coming in, and don't have much time, give it to the P-38's; they can really get up there. If it's above 20,000 feet they make their runs, go on out far enough to make a turn, and come back for another run, When the P-38's were sparring around with me, they would buzz way down below me, take a look, then go up through a hole in the clouds, take a short look around and come back down. They ran all around the sky while I was doing my best just to stay where I was.

Q. Was any attempt made to use them at the limit of their range?

A. They went clear up to Bougainville. They sent P-38's to fly cover on B-17's and on B-24's. There would be Zeros above them and below them would be more Zeros, float bi-planes and float Zeros, but their orders were to stay in formation with the bombers. If any of the enemy fighters made an attack, they'd just pull up, give a short burst, and the enemy fighter would pull right back up out of range. When they failed to do this one day, three of them were shot down. They went down below 20,000 feet to get some "easy meat", (these float bi-planes that can turn on a dime) - went down and tried to dogfight - that was the end of three P-38's.

LEBillfish
07-02-2010, 07:05 AM
http://www.j-aircraft.org/smf/index.php?topic=4619.0

K2

M_Gunz
07-02-2010, 10:49 AM
I'm just waiting for the mention of the uber-cloverleaf-turn-trick that no enemy could beat, LOL!

JtD
07-02-2010, 12:23 PM
The P-38 very much dominates the Ki-43 in vertical maneuvers. So try climbing, zoom climbing, and attacking from an altitude advantage. And in case things go bad, just push the nose down and dive away.

Or for more detail, check out LEBillfish's link.

LEBillfish
07-02-2010, 02:03 PM
You guys really want a kick in the pistachios?

Remember those arguments/threads a few months ago wherein claims about the Ho-103 12.7mm machine cannon's shells were claimed to be so powerful, like 20mm powerful....Naturally everyone including myself all over that one....and then to make it worse another would chime in with other very outlandish claims?

Well I received an email from Mr. R. Dunn......If you don't know who that is well let me put it to you this way.....Every writer of Japanese aircraft and their units count on his work. The Federal Government counts on his research and advice about actual historical and current military matters, and if you ever saw his credentials and accomplishments you'd feel like a CWOS tard-boy.........Mr. J.Long above the same about the aircraft themselves, same kind of weight as to research, and those into camouflage and markings obviously knowing Mr. J. Lansdale.

Anywho...back to the email....Here a post I made elsewhere as I then slowly back away eating my helping of crow.

We often hear about how weak and ineffective Japanese armaments were, and in kind via subsequent testing, is often confirmed. What most data fails to mention however not having a full understanding of Japanese armaments and aircraft is that just like all other nations their equipment evolved, yet often the testing was not reperformed showing the latest and greatest.

One of the most commonly stated aspects being how weak to almost counter-productive Japanese explosive ordnance was due to "initially" being based off of old post WWI Vickers designs. Naturally that places the Japanese 12.7x81SR round right in there with the Breda, and as you can see in the link below placing it much below the U.S. .50 caliber.

http://www.quarry.nildram.co.uk/WW2guneffect.htm

Today I received an email however wherein Mr. R. Dunn without question being one of the world authorities of Japanese air combat in WWII, was posed a question by Mr. N. Smith who at the time (October 43) was a 40th Fighter Squdron pilot in New Guinea piloting a P-39. On a particular encounter he took a single hit, this a brief of his remarks (from email, actual combat report on hand).....

" E. Rogers and I have discussed a 40th Fighter Squadron mission to Finschafen on October 27, 1943, in which my P-39 took a hit from a 20 mm projectile. At the time I was concentrating on our attack on the Japanese bombers, but I was aware that we were coming in below a bunch of Japanese fighters, which I thought numbered about twenty.

The projectile came almost straight down from above and went through my right wing, severing my right aileron cable and leaving a perfectly clean hole. When I got back to Nadzab, the ground crew said the hole in my wing was done by a 20 mm gun.

I have recently learned about the two groups of Ki-61s that were based at the Wewak air strips at that time, and am inclined to think that my plane was hit by a 20 mm Mauser cannon from one of those Ki-61s, as I am clear that the Ki-43s did not carry anything heavier than 13.7mm[sic] at that time, and the A6Ms were not working in that area then."


Mr. Dunn's partial reply;

"First, as to the 20mm hit - this was almost certainly a 12.7mm hit. Allied experts tested Japanese explosive 12.7 rounds and found they had an explosive effect very close to an <span class="ev_code_YELLOW">Allied Hispano 20mm round</span>. I don't know whether your hit was an explosive round or not. This mistake is easy to make and I have encountered it before, that is, Allied pilots report hits by 20mm rounds when their opponents had nothing heavier than 12.7mm. The first Type 3 fighters with four 12.7mm guns did not arrive in New Guinea until November 1943. The first with 20mm cannon did not arrive until 1944."

Now go back up and look at the chart again http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif I myself until this email having always argued to the contrary myself.

K2

M_Gunz
07-02-2010, 09:15 PM
If the shot left a perfectly clean hole and was AP then it's no problem to measure the hole diameter and know what diameter the shot was. If it hit at an angle it would leave an elliptical hole where the minor diameter is the diameter of the round. Unless 12.7mm bullet leaves a 20mm wide hole?

A perfectly clean hole from explosive round hit could happen. I'd like to see the difference between entry and exit holes.

LEBillfish
07-02-2010, 09:40 PM
Well in the actual combat report it mentions how the underside of the wing was burned. Such a direct hit would cause naturally deformation of the fragile round, it sounding to me as though it exploded the other side. Add to that a round passing through soft enough material may cause it to also deform larger then the actual slug, and the size of the hole becomes at this point all guessing.

Point being....There were no 20mm Ki-61 there at that time and 20mm Ki-43 never existed. A6M's were not in the area busy elsewhere.

IOW....It could only of been a 12.7mm round, and they apparently had more power once further developed then we realize from the chart posted above. I'll try and run down the testing of them.

K2

JtD
07-02-2010, 11:25 PM
I'd love to finally see that test.

M_Gunz
07-03-2010, 12:21 AM
I've put holes through soda cans, paint cans and even a steel fertilizer spreader bin with .22's that when walked up to a .22 just fit through. I've done it with layers of slate rock to try and see the holes get bigger as the bullet widened and the thing is that with 7 layers of slate about 1/8" thick the holes hardly got wider and were very clean which I did not predict.. but then I was only 14 and the experience was a lesson to me.

I would expect an explosive bullet might widen the hole if it was expanding on the way through though. I only had .22 LR hollowpoints and shot from about 10 feet through the slate layers, from farther through cans and junk. Perhaps the ground crew did not measure the holes they saw before telling the pilot what they thought, but I bet they knew 50 cal from 20mm the same way they knew what wrench to grab when looking at the head of a bolt. I believe what was written there and I believe those guys knew what they were saying. But did those 12.7's have the energy to put them in the same class with 20mm shells when it came to structural hits? Mike Williams grades them as less in terms of energy. Perhaps they were more efficient than the Hisso shells in ways that Mike Williams does not account for? Just the timing of the fuse and the spacing of the part of the plane they hit (in that case, the wing) can make a big difference in the effect. Would they do as well against the back of an armored seat or an engine?

BTW -- from 1/2" (12.7mm) to 4/5" (20mm) diameter is over half as much more. That's a LOT of spread.

K_Freddie
07-03-2010, 07:34 AM
Nobody's taken into account the relative speeds of a/c and shell, which sounds close to the perpendicular. This and possble shell 'wobble' would make a larger entrance hole that could look like a larger shell.

LEBillfish
07-03-2010, 07:53 AM
Originally posted by JtD:
I'd love to finally see that test.

Agree....

Hearing about it from so many to me just smacks of a perpetuated myth. I see it all the time when investigating Japanese markings, aircraft and so on. Quite frankly in most cases the myths often more perpetuated then fact.

However, I also have seen in great detail Mr. Dunn's research. Nothing he says, even the most minor of sentances is ever simply off the cuff, opinion, or memory. Everything is stated backed 100% by cross-checked documentation and research.........To that end if he makes a statement I stop and listen being one of the few people I know of to not question.

Max....Was your pop can that you shot at perpendicularly moving at 300Km/h also considering the much higher velocity of your round? Was your paper thin pop can the thickness and strength of aircraft aluminum? Does your .22 of a single material deform as much as this 12.7mm Breda (similar to Ho-103HE) seen at the far right?

http://www.quarry.nildram.co.uk/FG127Breda.jpg

etc..

Basically......We all sitting here yacking don't have a good answer past anecdotes we regurgitate from vague memory and links to websites we take as gospel........More so, I'm sitting here challenging my own opinion and statements, basically trying to prove myself wrong.

Yet when Mr. Dunn speaks, I listen....Let me see what I can do about getting this so often quoted report. In the mean time here are the combat reports from Mr. N. Smith's encounter.

http://78sentai.org/78V/albums/recon/10001/prev_2010-06-28-0945-54.jpg

http://78sentai.org/78V/albums/recon/10001/prev_2010-06-28-0947-30.jpg

K2

ElAurens
07-03-2010, 10:33 AM
This would explain many of the downings of very heavy US fighters (P 47s in particular) by Japanese Army types armed only with 2 12.7mm guns synced for firing through the prop disc, hence low rates of fire, comparatively.

Daiichidoku
07-03-2010, 11:58 AM
a lot of this is what lockheed test pilots were saying to service combat pilots all along



"The chief fighting characteristic of,the '38, aside from its terrific firepower, is its high ceiling. In all of this fellow's sorties he has never encountered an enemy plane which could top the '38's ceiling. "Because of its excellent performance at high altirude, the strategy for combat," he said, "is to force the battle upward whenever possible," As the altitude increases the '38 gains the advantage over ships not designed for the thinner air."

http://img.photobucket.com/albums/v479/Daiichidoku/S_i5p4i1.jpg


"Another point of interest was that the '38 could not only climb higher, but faster than any of the planes encountered. This is important, and as a result of this characteristic an effective combat technique has been developed that of outclimbing the enemy, and when he stalls out, just rolling over and picking him off."

http://img.photobucket.com/albums/v479/Daiichidoku/S_i5p5i1.jpg

Because of the '38's counter-rotating propellers there is no torque and no tendency to slip off on either wing at the top of your climb. As a result you can obtain every bit of the maximum climb. Because of torque, most single engine fighters tend to slip off just. below their maximum ceiling, thus leaving themselves wide open for the '38 pilot who awaits this moment overhead, and then peels off for the kill.

In combat, use the 38's superior speed and climb ability to keep on top of the enemy. You all know that the 38's rate of climb is approximately the same from 140 MPH to 180 MPH. This range relieves you of keeping your eyes glued to the air speed indicator when you're trying to get up there the fastest; and the maximum of 180 MPH gives you the dual advantage of not only getting upstairs faster, but also covering more distance in the same time than your enemy whose best climbing speed may be 145 or 150 MPH.

Sillius_Sodus
07-03-2010, 01:02 PM
I like to use a high speed, shallow climb of around 500fpm. It's effective against KI-43's (at least AI), a bit less so against A6M's, KI-61's and most late-war Japanese aircraft.

M_Gunz
07-03-2010, 01:19 PM
It seems weird to me BF that when I post basically agreeing with 90+% of what you wrote, you call it a challenge. Can I take that as you don't know what I was writing but just assumed I must be objecting to most or all of it? You've done this with me before. Is it the idea that I don't agree with everything including the suppositions you make that are not supported?

.22 LR went through more than just soda cans. I gave four examples but then I have spatial math abilities telling me that a 1250 fps .22 bullet moves a bit faster than 186.45 mph. Give the soda can 300kph velocity = 273.46 fps. The bullet itself is less than 1/2" long and spinning faster than any drill so the hole will be slightly, by about a bullet length x 273.46 / 1250 larger in one direction than the width of the hole, ie NOT ROUND with the width of the hole as testimony of the diameter of the bullet that went through.

My point that you missed is that in all cases of shooting those holes with SOFT LEAD HOLLOW POINT BULLETS is that the metal (and slate rock) did not push, peel or jump back to make a wider hole. If you want to, go check ballistics or forensics sites to see if that happens elsewhere and please I don't mean very small amounts but actual large amounts on the scale of these bullets. At the extreme velocities those shots travel the holes through material thin and soft enough to present no great obstacle to the bullet tend to be rather clean and not quite perfectly precise even given the small wobble (compare the precession rate to the actual speed of the bullet to get some perspective Freddy, without the relation you end up with a false picture. There's Youtube pictures of bullets shot and impacting materials at 1,000,000 frames per second to help if needed though the plates they strike do not tend to be terribly thin you can see the spin rate compared to the forward motion quite clearly). Especially check the forensics angle, how they determine the bullet diameters from the sizes of holes they make, how they can guess at the speed of the target, etc, then check AP-hit damage reports on WWII fighters and lastly when you say "but explosive bullets..." then go back and read what I wrote agreeing and trying to guess why the holes would be about so wide and agreeing TOTALLY that the ground crew would know the difference so WHY YES them holes must have passed expert witness to be what they would see from 20mm damage even when and where there were no 20mm in use as you state based on hole size. We don't agree on the HOW, we do agree on the WHAT. Neither of us has taken more than a guess on the how either. I was just trying to clear up that thin soft aluminum does not spread back under such impacts at least to the extent of from 12.7mm to 20mm width.

Of course you want to compare jacketed and even brass tipped bullets against soft lead hollow points for which will expand more on contact with soft, thin aluminum? Answer is so close to none you will need precision calipers to know the difference if even then. Not that it matters since the hit was clearly by an explosive bullet moving in the Mach 2 speed range. The fact that it left a clean hole on one side, severed the control cable and left a burned hole of undisclosed proportion commensurate with 20mm HE from a Hispano might tell that the blast wasn't much if at all on the upper surface of the wing which is why I wonder if the casing expanding due to the blast might be the cause of the wider entry hole but what the hey why not forget facts, get really silly and say them bullets must get wider because of the spin pulling them wider? Since I AGREE about the hole size then why not just grab at any explanation that one single truth might support and forget the rest. After all, IT DID HAPPEN and we both agree on that!

Or perhaps somehow when I write YES it really means NO?

M_Gunz
07-03-2010, 01:24 PM
Originally posted by Daiichidoku:
In combat, use the 38's superior speed and climb ability to keep on top of the enemy. You all know that the 38's rate of climb is approximately the same from 140 MPH to 180 MPH.

The first sentence agrees with all I've read by the men that used P-38's successfully. But please show where any of them told to run at less than or even as slow as 200 MPH in combat. What Foss wrote, they zoomed. They used speed and climb.

R_Target
07-03-2010, 01:31 PM
During the war, 5th Air Force put together a group of essays on tactics by leading aces of 5th Fighter Command. It's called "Twelve to One", and is essential reading for budding P-38 aces. Osprey publishes it in book form, and it's also included in William Hess' Pacific Sweep, which you can get for pennies at Amazon or wherever.

Parts or all of it may even be available online if anybody feels like looking for it.

LEBillfish
07-03-2010, 01:38 PM
Originally posted by M_Gunz:
It seems weird to me BF that when I post basically agreeing with 90+% of what you wrote, you call it a challenge.......................
Or perhaps somehow when I write YES it really means NO?

Huh what?

and the only time I used the word "challenge" was in this sentance....


More so, I'm sitting here challenging my own opinion and statements, basically trying to prove myself wrong.


K2

Xiolablu3
07-03-2010, 01:41 PM
Interesting stuff, especially the stuff about the 12.7mm machine guns vs 20mm cannon.

Thanks for posting

VW-IceFire
07-04-2010, 07:55 PM
Originally posted by Xiolablu3:
Interesting stuff, especially the stuff about the 12.7mm machine guns vs 20mm cannon.

Thanks for posting
Definitely interesting! BUT the trouble is that every time I'm flying a Ki-61 Otsu online I'll be thinking to myself "Gee I wish I had explosive bullets". Sounds like a pretty good weapon if that was working properly. Quite the hit to that P-39.

Andrew_H
07-05-2010, 02:27 PM
I've been flying IL2 for a while and can't really get the hang of it, especially planes like the P38 that require high speed and can't turn. I've read the theory about energy fighting but I just don't get it, if the enemy plane is behind you then you have to turn round, so how do you do it if he can turn better than you? If I extend the distance before turning I just end up in a series of head-to-head shooting matches...? Help!

Xiolablu3
07-05-2010, 04:27 PM
Originally posted by Andrew_H:
I've been flying IL2 for a while and can't really get the hang of it, especially planes like the P38 that require high speed and can't turn. I've read the theory about energy fighting but I just don't get it, if the enemy plane is behind you then you have to turn round, so how do you do it if he can turn better than you? If I extend the distance before turning I just end up in a series of head-to-head shooting matches...? Help!

Well thats the problem, Andrew. WW2 pilots fought in pairs or fours for a reason.

Try and use the vertical as much as you can. And keep faster and higher than the enemy. Remember, you dont HAVE to dogfight at all. You can zoom down from on high, take a shot and then zoom back up, in ANY aircraft. This makes it almost impossible for the enemy aircraft to get even a shot at you

M_Gunz
07-05-2010, 09:11 PM
As long as you are significantly (10+%) faster, use the vertical. Slower enemy flat turn advantage does not work in the vertical. You don't have to go straight up or down either, esp going up keep your speed higher. Learn to do wingovers, yoyos, half-loops and loops depending on your speed of course -- don't loop or half-loop if it will leave you slow at the top.

Of course the enemy might zoom and climb as well. So what you do if you've got no brains is to zoom for 30 seconds and then wait for him to catch up to your height after another 30 or so before you get back to the fight -or- you zoom for less than 10 seconds seconds and reverse as part of that while he is trying to get to your height. If that doesn't put you in a great attack position right away but *does* give you some edge then repeat to add edge upon edge until you have the big advantage or your enemy wises up and runs.

Look for the quote from Joe Foss about mock fights with P-38's. What was he flying? The P-38 would stay out of reach moving too fast to catch and then zoom up. That's the quote you want to find and think about in tactical sense. No math required.

Foss 26 April 1943: (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2481041186?r=2481041186#2481041186)


If it's above 20,000 feet they make their runs, go on out far enough to make a turn, and come back for another run, When the P-38's were sparring around with me, they would buzz way down below me, take a look, then go up through a hole in the clouds, take a short look around and come back down. They ran all around the sky while I was doing my best just to stay where I was.

My _assumption_ is that doing my best just to stay where I was refers to to where he was in relation to the P-38. I doubt it refers to where he was over the map but who knows?


They sent P-38's to fly cover on B-17's and on B-24's. There would be Zeros above them and below them would be more Zeros, float bi-planes and float Zeros, but their orders were to stay in formation with the bombers. If any of the enemy fighters made an attack, they'd just pull up, give a short burst, and the enemy fighter would pull right back up out of range. When they failed to do this one day, three of them were shot down. They went down below 20,000 feet to get some "easy meat", (these float bi-planes that can turn on a dime) - went down and tried to dogfight - that was the end of three P-38's

From his May 1943 medal citation it looks like he was flying an F4F at the time. (http://www.acepilots.com/usmc_foss.html)


On 15 January 1943, he added 3 more enemy planes to his already brilliant successes for a record of aerial combat achievement unsurpassed in this war. Boldly searching out an approaching enemy force on 25 January, Capt. Foss led his 8 F-4F Marine planes and 4 Army P-38s into action and, undaunted by tremendously superior numbers, intercepted and struck with such force that 4 Japanese fighters were shot down and the bombers were turned back without releasing a single bomb.

WTE_Galway
07-05-2010, 09:27 PM
The man himself and his ride http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

http://www.sddot.com/fpa/aeronautics/images/joefoss_plane.jpg


120 mph slower than p38 (320 mph vs 443 mph)
4500' lower service ceiling than p38 (39,500' vs 44,000')
2700 ft/min less rate of climb than a p38 (1950 ft/m vs 4750 ft/min)

which explains the "doing my best just to stay where I was" http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

but half the wing loading http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif and a better dogfighter in the get down low and turn with the zeroes sense

Kettenhunde
07-05-2010, 09:35 PM
You don't have to go straight up or down either, esp going up keep your speed higher


No you do not have just go straight and down. However, the steeper the angle and faster the velocity, the faster the aircraft can reverse.

For example a FW-190A8 zooming from best load factor takes ~17 seconds to zoom to stall @45 degrees and reverse to any heading in a hammerhead.

It takes the a Spitfire Mk IX ~17 seconds to make a complete turn at sea level.

In otherwords, the ability to put the nose on a target is about equal.

M_Gunz
07-05-2010, 11:50 PM
That FW can roll and pull onto a new heading in about half that time.. if he is already heading up before the clock starts. There is no need to stall along with the subsequent associated post-hammerhead speed recovery required. Time spent slow is time and distance lost.

How steep you zoom depends on a number of factors, air speed being a big one.

I was reading about McGuire's last fight where he commanded his men to not drop their belly tanks. He was pulling hard to come around on a Ki-43 and pulled harder when that no-torque P-38 did a snap roll and sent him down hard. So the P-38 is not without surprises when pushed too far, not always the gentle departure.

JtD
07-05-2010, 11:57 PM
Guess that would depend on what you do with the rudder. Lots of yawing results in asymmetrical airflow and therefore asymmetrical stalling.

Kettenhunde
07-06-2010, 05:02 AM
That FW can roll and pull onto a new heading in about half that time.. if he is already heading up before the clock starts.

Why would you start the clock late to make a comparison?

That is like undervaluing the airplanes thrust, adding additional weight, and pulling a ridiculous load factor upon entry.



There is no need to stall along with the subsequent associated post-hammerhead speed recovery required. Time spent slow is time and distance lost.

The only point was to illustrate the fact that turning small circles is not the only way to get an airplanes nose pointed in a different direction.

Kettenhunde
07-06-2010, 05:09 AM
pulled harder when that no-torque P-38 did a snap roll and sent him down hard.

The P38 has a rather complicated wing tank arrangement.

The danger to a maneuvering fighter with wing tanks is different amounts of fuel in the tanks requires asymmetrical lift.

In fact the differences can easily cause such things as a snap roll. That fuel also can slosh altering the stability and control characteristics.

horseback
07-06-2010, 08:32 AM
Yeah, the P-38's droptanks were a lot bigger than the ones normally carried by other fighters; it stands to reason that they would likely not have internal baffles and that the fuel might be drawn unevenly.

Could the P-38 even draw from both drop tanks at the same time?

cheers

horseback

DrHerb
07-06-2010, 08:53 AM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">pulled harder when that no-torque P-38 did a snap roll and sent him down hard.

The P38 has a rather complicated wing tank arrangement.

The danger to a maneuvering fighter with wing tanks is different amounts of fuel in the tanks requires asymmetrical lift.

In fact the differences can easily cause such things as a snap roll. That fuel also can slosh altering the stability and control characteristics. </div></BLOCKQUOTE>

Aren't the P-38's aux tanks somewhat centerlined?

Kettenhunde
07-06-2010, 09:26 AM
Aren't the P-38's aux tanks somewhat centerlined?

No more so than the main wing tanks....

http://img706.imageshack.us/img706/7066/fueltanks.jpg (http://img706.imageshack.us/i/fueltanks.jpg/)

JtD
07-06-2010, 09:52 AM
Originally posted by horseback:

Could the P-38 even draw from both drop tanks at the same time?

Typically, the left engine would draw from the left tank, the right from the right. There were cross feed lines, but that wasn't standard procedure.

Kettenhunde
07-06-2010, 10:14 AM
A fuel imbalance can occur for many reasons, including acceptable variations in the performance of fuel system components, variations in engine fuel burn characteristics, faults in internal fuel system components, or fuel system or structural faults that cause fuel to leak overboard.

http://www.boeing.com/commerci...9/fuel_textonly.html (http://www.boeing.com/commercial/aeromagazine/aero_09/fuel_textonly.html)

Fuel imbalance is a common issue in any aircraft equipped with wing tanks. It is the nature of the beast and one reason why many European fighter designs in WWII avoided wing tanks.

You will also find many competition aerobatic designs avoid them as well.

WTE_Galway
07-06-2010, 08:14 PM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> A fuel imbalance can occur for many reasons, including acceptable variations in the performance of fuel system components, variations in engine fuel burn characteristics, faults in internal fuel system components, or fuel system or structural faults that cause fuel to leak overboard.

http://www.boeing.com/commerci...9/fuel_textonly.html (http://www.boeing.com/commercial/aeromagazine/aero_09/fuel_textonly.html)

Fuel imbalance is a common issue in any aircraft equipped with wing tanks. It is the nature of the beast and one reason why many European fighter designs in WWII avoided wing tanks.

You will also find many competition aerobatic designs avoid them as well. </div></BLOCKQUOTE>

Asymmetric flight may also be involved. It was not unusual to use asymmetric throttle to enhance combat turning in the p38. Remember that the P38 props rotate the "wrong way" compared to most counter-rotating designs. The p38 has two critical engines .

According to Kelly Johnson they did it that way because it made it a more stable Gun platform.


Craig Wall http://yarchive.net/air/p38.html :
I met Kelly in about '82 or '83 at a seminar in Norman, Oklahoma. I asked him about the P-38 props turning outboard at the top, giving two critical engines.

I though I knew the answer: because the spiral flow off the props was opposite the tip vortices, the ship should be cleaner. And it is. But that wasn't the reason he gave....

He just said "it made a better gun platform".

That was it. The entire purpose of the airplane was to shoot, and anything that made it do that job better was the deciding factor in all decisions like the prop rotation, etc...

He said they actually tried it in every possible combination of prop directions, and that's the one that worked best and gave the highest gunnery scores.

M_Gunz
07-06-2010, 08:57 PM
Johnson said better gun platform, you say more stable but how else to get highest gunnery scores? What if "better" includes speed, climb, turn, range, ceiling to be able to get in position for a shot?

Consider many WWII combat planes that were -very- stable platforms. Like dive bombers, level bombers, torpedo planes.. those kind of planes. Very stable but not terribly quick in starting maneuvers, not agile. Not fighters. But okay for interceptors which is what the P-38 was for. But I doubt that faster and higher weighed in *against* higher gunnery scores.

WTE_Galway
07-06-2010, 09:48 PM
Originally posted by M_Gunz:
Johnson said better gun platform, you say more stable but how else to get highest gunnery scores? What if "better" includes speed, climb, turn, range, ceiling to be able to get in position for a shot?


The design was for a military operational aircraft not a game so "acemaking" considerations were probably less of a consideration than reliable results http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Regardless .. I was just repeating what most sources have to say about the unusual engine arrangements:



http://www.fighter-planes.com/info/p38_lightning.htm on early development:

The prototype Lockheed Model 22, later designated XP-38, rolled out in December 1938 and first flew on January 27, 1939. It set a cross-continent speed record by flying from California to New York on February 11, 1939 in 7 hours and 2 minutes, including two fuel stops. Unfortunately, the prototype landed short of the runway in New York and was wrecked, much to the distress of the Lockheed engineering team. They had opposed the flight, but it was done at the insistence of General Henry "Hap" Arnold, commander of the USAAC, as a publicity stunt.

Although the loss of the aircraft was a serious setback (putting the program back two years), on the basis of the record flight the Air Corps ordered 13 YP-38s in April 1939. If the XP-38 had not been destroyed, orders would not have been placed until the prototype had been thoroughly evaluated.

However, manufacture of the YP-38s proved troublesome, and the first didn't roll off the production line until September 1940, with the last delivered in June 1941. Although they looked much like the hand-built XP-38, they were substantially redesigned and differed greatly in detail. They were lighter, and there were changes in engine fit, particularly in that propeller spin rotation was reversed, with the blades rotating outwards (away) from the cockpit at the top of their arc rather than inwards as before. This change, according to Kelly Johnson, improved the aircraft's stability as a gunnery platform.


... The most dangerous problem was that both engines were "critical" engines losing one on takeoff, which happened often, created "critical torque," rolling the plane towards the live engine's wingtip, rather than the dead engine's. Normal reflex in pilots flying twin engine aircraft would be to push the remaining engine to full throttle when they lost an engine on takeoff, but in the P-38, the resulting critical torque would produce such an uncontrollable level of asymmetric roll that the aircraft would flip over and slam upside-down into the ground. Eventually, procedures were devised to allow a pilot to deal with the situation by reducing power on the running engine, feathering the prop on the dead engine, and then increasing power gradually until the aircraft was in stable flight.




btw ... its also possible that asymmetric flight with a critical engine on a twin boom aircraft is substantially more dangerous than with a normal twin engine aircraft. Check out the Critical Engine factors on this trainer and visualize the effect of a twin boom instead:

http://media.avit.und.edu/f4_I.../060302/mainmenu.php (http://media.avit.und.edu/f4_Inop%20Engine%20Trainer/f1_Inop%20Engine/060302/mainmenu.php)

Daiichidoku
07-07-2010, 09:05 AM
Originally posted by WTE_Galway:
The most dangerous problem was that both engines were "critical" engines losing one on takeoff, which happened often, created "critical torque," rolling the plane towards the live engine's wingtip, rather than the dead engine's. Normal reflex in pilots flying twin engine aircraft would be to push the remaining engine to full throttle when they lost an engine on takeoff, but in the P-38, the resulting critical torque would produce such an uncontrollable level of asymmetric roll that the aircraft would flip over and slam upside-down into the ground. Eventually, procedures were devised to allow a pilot to deal with the situation by reducing power on the running engine, feathering the prop on the dead engine, and then increasing power gradually until the aircraft was in stable flight.


btw ... its also possible that asymmetric flight with a critical engine on a twin boom aircraft is substantially more dangerous than with a normal twin engine aircraft.



as you quoted above, take off was the really critical time for the 38, ironically, given its great take-off performance;
with a normal combat weight take off speed signifigantly less than that of its minumum single engine failure takeoff safety speed, wise pilots had to be sure to keep it stuck a bit longer..

Tony Levier would display single engine takeoffs and slow rolls into the dead engine in an unmodified 38, during feb 44



more from "hangar flying"

When an engine quits, reduce the power on the live engine and correct yaw with hard opposite rudder; then increase power as much as you can hold. The dead engine's mixture control should be set to idle cut-off, to reduce fire hazard by stopping the flow of fuel. Set the feathering switch to full feather, and pull the throttle back to "close". That's all there is to getting set for single engine flight.

If the flight is going to be for any duration though, you'll find that the following operations make for safer and better flying: turn off the booster pump of the dead engine, trim the rudder tab, close the tank selector valve, the prestone shutter, and the oil cooler flap of the dead engine.

Don't burn up your good engine-31 inches of mercury with 2300 R.P.M. is satisfactory cruising power, and for single engine climb 37 inches with 2600 R.P.M. is recommended. The use of more power is unnecessary. The single engine power stall occurs at 90 M.P.H. indicated, and you will experience a big change in directional trim with change in speed, comparable to the torque effect in single engine airplanes.

Single engine landings are a cinch - but never count on a twin engine plane maintaining altitude with both the gear and flaps full down. Once full flaps are extended the landing MUST be made, so extend flaps 100% only when you see it's "in the bag".

http://img.photobucket.com/albums/v479/Daiichidoku/S_i3p41.jpg

JtD
07-07-2010, 09:17 AM
Flying on one engine has been a great part of the P-38 video posted on this board some days ago (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/3871006768). If you haven't seen it, check it out.

Kettenhunde
07-07-2010, 09:24 AM
It was not unusual to use asymmetric throttle to enhance combat turning in the p38.

That is very true and could have been the case. Fuel imbalance is just a very common condition in wing tank equipped aircraft that also could have caused a stall spin accident.

If you have much experience flying one, you can feel on the controls when you have an imbalance too.


The p38 has two critical engines .

By definition or at least what I was taught during my twin rating was the critical engine is critical because aerodynamically it causes a larger effect than the non-critical engine.

In a counter rotating twin, both engines cause equal effect and therefore the P38 does not have a critical engine.


Other twins overcome the problem, of having a critical engine, by having counter-rotating engines (right engine rotates counter-clockwise) and the effect of loosing either one of the engines would be the same.

http://www.pilotscafe.com/arti...irplane.html?start=1 (http://www.pilotscafe.com/articles/1-flight-trainingtutorials/3-engine-inoperative-principles-in-a-twin-airplane.html?start=1)

Kettenhunde
07-07-2010, 09:36 AM
but never count on a twin engine plane maintaining altitude with both the gear and flaps full down.


In a twin, the reason for the second engine is to ensure the aircraft makes it all the way to the crash site.

JtD
07-07-2010, 11:22 AM
A critical engine is one where the prop tip moves upwards towards the wingtip, and downwards towards the fuselage. It's the engine that is actually less critical to operate, or more critical to lose.

The reason for this are effect of thrust vectors and yaw moments, which either work against or with the forces that result from the loss of the other engine. Take for instance the torque of the engine, and assume a left engine failure, it is more critical if the right engine rotates clockwise, then when it rotates anti-clockwise (viewed from behind).

Standard configurations of twin engined aircraft usually have just one critical engine, because because both of them rotate the same direction, so one of them will be uncritical.

Usually on twins with counter rotating props, both engines are less critical to lose (i.e. going down inside, up outside). On the P-38, however, both of them were critical to lose (i.e. prop going up inside, down outside) - it was done that way because it gave best performance.

Kettenhunde
07-07-2010, 01:35 PM
A critical engine is one where the prop tip moves upwards towards the wingtip, and downwards towards the fuselage.

Here we go again.....

The engine that has the largest effect on the aircraft's handling is termed the critical engine.

From the Federal Aviation Regulations:


Title 14: Aeronautics and Space
PART 1—DEFINITIONS AND ABBREVIATIONS:

Critical engine means the engine whose failure would most adversely affect the performance or handling qualities of an aircraft.

http://ecfr.gpoaccess.gov/cgi/....1.1.1.0.1.1&idno=14 (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div8&view=text&node=14:1.0.1.1.1.0.1.1&idno=14)

It does not matter which direction the P-38 counter-rotating propellers turn, both engines have the same magnitude effect on the aircraft's handling. Losing the right or the left engine makes no difference on the magnitude of aerodynamic forces.

Therefore, there is no definition in aviation in which the P38 has "two critical engines".

Honestly, that is very funny if you think about it.

Tell me, of the two "critical" engines on the P38, which has the largest aerodynamic effect??

Maybe it depends on if you are flying with the rotation of the earth or against it, JtD?


The critical engine is the engine whose failure would most adversely affect the performance or handling qualities of the airplane. (FAR 1.1).

http://www.pilotscafe.com/arti...irplane.html?start=1 (http://www.pilotscafe.com/articles/1-flight-trainingtutorials/3-engine-inoperative-principles-in-a-twin-airplane.html?start=1)


The critical engine of a multi-engine, fixed-wing propeller-driven aircraft is the one whose failure would result in the most adverse effects on the aircraft's handling and performance.

http://www.skybrary.aero/index.php/Critical_Engine

What JtD describes in the outer blade tip down results in a higher Vmc but still the aerodynamic effects are the same which means NO CRITICAL ENGINE.

Now that being said, let's not confuse aeronautical terms with what is important.

Twin engine aircraft are designed to fly with two engines. Losing an engine in one is critical and will most like result in a crash. If you are below Vmc, most likely a fatal one.

Here is a good discussion between pilots on the P-38 and critical engines:

http://www.pprune.org/flight-t...ting-propellers.html (http://www.pprune.org/flight-testing/344384-counter-rotating-propellers.html)

Daiichidoku
07-07-2010, 01:42 PM
not critical by definition in the context above, but port engine is critical, in that it has the generator, best to lose starboard eng., if you have to lose one at all http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

M_Gunz
07-07-2010, 01:44 PM
Originally posted by JtD:
Usually on twins with counter rotating props, both engines are less critical to lose (i.e. going down inside, up outside). On the P-38, however, both of them were critical to lose (i.e. prop going up inside, down outside) - it was done that way because it gave best performance.

The vortex spin from the props are opposite spin to the wingtips, the vortexes turn together where they touch whereas prop turning the other way you'd have two vortexes 'rubbing' instead of rolling between engine and wingtip, probably not without some effect on stability as well as speed?

Kettenhunde
07-07-2010, 01:47 PM
not critical by definition in the context above, but port engine is critical, in that it has the generator, best to lose starboard eng., if you have to lose one at all

Exactly! That is important to the the aircraft systems and the P-38 is not the only twin to have such a set up where one engine runs some key subsystems.

However it does not mean the aircraft has a critical engine in aeronautical terms.

Daiichidoku
07-07-2010, 01:53 PM
Originally posted by M_Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
Usually on twins with counter rotating props, both engines are less critical to lose (i.e. going down inside, up outside). On the P-38, however, both of them were critical to lose (i.e. prop going up inside, down outside) - it was done that way because it gave best performance.

The vortex spin from the props are opposite spin to the wingtips, the vortexes turn together where they touch whereas prop turning the other way you'd have two vortexes 'rubbing' instead of rolling between engine and wingtip, probably not without some effect on stability as well as speed? </div></BLOCKQUOTE>


Tony Levier was told, when the inward rotating XP config was changed to outward, on the YP's, that it added more longitudinal stability vs inward rotation

M_Gunz
07-07-2010, 01:55 PM
One way, if you lose an engine then you would apply full power to the good engine and have that power to fly with.
The other way, if you lose an engine then you lower power on the good engine and have to stabilize before you can increase power on the good engine. This is the critical one, no?

Kettenhunde
07-07-2010, 02:23 PM
One way, if you lose an engine then you would apply full power to the good engine and have that power to fly with.
The other way, if you lose an engine then you lower power on the good engine and have to stabilize before you can increase power on the good engine. This is the critical one, no?

I have see procedures that differentiate between the critical engine.

Most POH's do not as the basic procedures are the same.

The critical engine has more forces. That means higher speeds, banking, and more control input required.

JtD
07-07-2010, 03:02 PM
Most means most. If two are equally most, they both can be considered uncritical, or critical, however the proper interpretation. That's part of the definition. However, if you have to certify certain aspects of aircraft accounting for the loss the critical engine (as a worst case scenario), having two equally critical engines does never free you of the certification. Usually, it gives you the option to chose one of them. So in that sense (which is the common one), a multi engined aircraft very well has multiple critical engines.
For instance, if you have to prove that your plane "can maintain altitude after the loss of the critical engine", you'll have to prove it. Even if all your engines have the same adverse effect. In that case you may get away by proving it for a random one, or you may have to prove it for any number up to all of them, depending on the dumbness involved in the certification. At any rate, they are all considered critical engines in that regard.
This of course is hard to pick up when simply parroting regulations or websites without having a clue about what's going on in aviation.

Anyway, I did not even say that they both of the P-38 engines were critical engines by the definition of any regulations. I was illustrating what makes engines critical on prop twins and pointed out that the P-38 has two of that kind installed. So please re-read.

Kettenhunde
07-07-2010, 04:45 PM
If two are equally most,

"equally most"... http://forums.ubi.com/images/smilies/25.gif

http://forums.ubi.com/images/smilies/partyhat.gif


I was illustrating what makes engines critical on prop twins

OK...


Title 14: Aeronautics and Space
PART 1— <span class="ev_code_YELLOW">DEFINITIONS</span> AND ABBREVIATIONS:

Critical engine means the engine whose failure would <span class="ev_code_YELLOW">most adversely affect the performance or handling qualities of an aircraft.</span>

http://ecfr.gpoaccess.gov/cgi/....1.1.1.0.1.1&idno=14 (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div8&view=text&node=14:1.0.1.1.1.0.1.1&idno=14)

Kettenhunde
07-07-2010, 04:58 PM
At any rate, they are all considered critical engines in that regard.


Baloney.

Tell that to an examiner and you will get it wrong.

WTE_Galway
07-07-2010, 08:41 PM
lol ... I seem to have sidetracked this thread.


OK, what I SHOULD have said is that an unusual feature of the p38 is they chose the worst direction for prop rotation in asymmetric flight conditions - so both engines now behave in a similiar fashion to what would have been the critical engine in a non counter-rotating p38 design.

The significant point is they did this to improve it as a gun platform based on gunnery tests, as opposed to making it faster, more maneuverable or reducing buffeting.

Getting back to the original point, asymmetric operation of a 1300 odd horsepower Allison with the prop rotating outwards in a light weight fighter may partially explain the snap roll described in the original post. Especially if fuel was distributed unevenly as well.

Another known issue with the p38 to consider is asymmetric deployment of the Fowler Flaps although in the incident in Gunz post you would expect Maquire to have mentioned that if it had ocured.

JtD
07-07-2010, 10:37 PM
Customer: "The plane must be able to maintain 200 knots in level flight after the loss of the critical engine."

Contractor: "My plane cannot maintain level flight let alone 200 knots after losing any one engine, but since both of them effect the plane equally in case of failure, the plane has no critical engine and that clause does not apply."

Apparently, there are morons on this planet who'd believe that nonsense and buy the plane. Lucky for us, they don't have a say in the business.

---
Galway, I don't think you sidetracked this topic, it was fairly clear what you wanted to state. But getting back to the P-38, could you please give more detail on the reasons for the decision, maybe (a link to) the source for the stability as a gun platform statement? I'd expect some handling advantages in the two engined conditions from that choice as well.

Kettenhunde
07-07-2010, 10:51 PM
Have you ever wondered why a manufacturer puts more engines on an airframe? There are many people who think that it's for safety; that a twin is safer than a single. After all, if one engine fails, well, you just keep on flying on the remaining one, right?

No. When one engine on a twin fails, you don't lose half of your excess thrust, you typically lose 80% to 90% of your excess thrust, which means that if you were climbing at 1200 fpm with both engines, if you configure and fly the aircraft perfectly after an engine failure, you will likely see around 200 fpm, which is pretty bad.

Most light twins, when operated anywhere near gross weight, have very marginal single-engine performance, and are very intolerant of pilot error in achieving a positive rate of climb. A non-turbocharged twin will typically have a single-engine service ceiling of around 5000 foot density altitude. So, an engine failure in cruise in summer means you're likely going to descend.


And remember, with two engines, you're twice as likely to have an engine failure.

http://www.avweb.com/news/airman/184438-1.html

M_Gunz
07-08-2010, 03:22 PM
And in a single engine plane when -an engine- quits is it any better except during takeoff or landing?

Kettenhunde
07-08-2010, 03:35 PM
And in a single engine plane when -an engine- quits is it any better except during takeoff or landing?


LOL.

Either way you are coming down. I think a very good argument can be made that a twin can be more dangerous. It gives one "hope" that seems to rarely pan out in the real world.

There is no guessing with the SE. If that one propeller is not turning and all you hear is the wind....you will be landing soon.

It is just a matter of enacting your plan.

Of course if your ADM is not good, it does not matter what airplane you fly.

Kettenhunde
07-08-2010, 03:50 PM
The significant point is they did this to improve it as a gun platform based on gunnery tests, as opposed to making it faster, more maneuverable or reducing buffeting.

I read that too and found it very interesting.

Here is what Lockheed engineers on the design team had to say:


Major Gilkey's premature encounter naturally generated considerable concern, especially with the Air Corps people involved with the new fighter programs. Much confusion existed, because the real causes and effects were not understood. It was first believed by many that the buffet problem was caused by tail flutter, a rather natural conclusion since this was a situation familiar to many, and a likely source of trouble. Control cable tensions, mass balance change, and stabilizer skin reinforcement were all explored experimentally in the flight program, but without any problem relief. Gear-door retention latches were redesigned to make sure doors remained closed during high-speed dives. No improvements were reported.

Movement of the horizontal tail vertically upward by bending the tail booms was flight tested (Figure 15). Results showed a slight loss in longitudinal stability, a 3-percent loss in speed, and buffet was aggravated.


Opposite propeller rotation was examined--no relief. Final choice of propeller rotation was based on longitudinal stability characteristics. It was found that inboard blades rotating up so that the propeller slipstream counteracted the tip vortices and lessened downwash at the tail made a favorable contribution to static stability.