Wimble Toot
Banned
The German pilots also referred to four-engined bombers as dicke autos, which google translate gives as 'fat cars' but was a colloquial German expression for furniture vans.
The German pilots also referred to four-engined bombers as dicke autos, which google translate gives as 'fat cars' but was a colloquial German expression for furniture vans.
Doing a little technical research and came across this report on testing the OTL P-38J-15-LO with Grade 100/150 fuel at 75"Hg. The interesting part in §C:
It looks like the ATL P-38J may end up having lower M.P. limits that originally thought unless Allison upgrades the Con.Rods.
It looks like the ATL P-38J may end up having lower M.P. limits that originally thought unless Allison upgrades the Con.Rods.
Then Allison should upgrade the connecting rods. Why not as they did improve other parts of the V-1710 engine over time like the bearings for example. The G versions were rated for more than 75 inches I think. I don't think it would be a huge stretch to see a slightly faster development of the V-1710 engine corresponding with the requirements the P-38 improvements are putting on the engine.
It sounds to me like all the other rods endured 12 1/2 hours at 1840 hp at 3000 rpm and 75". What sort of up-grade did you have in mind?
A very likely scenario. The ATL F-29 Engine being developed for TTL P-38J has already upgraded the crank to one of a 12-counterweight type instead of 6. Better metallurgy available in '43/'44 vs. 1939 should allow them to install stronger Connecting Rods as well. Until that happens, a likely solution will be to reserve AN-44-1 (104/150) fuel for the single engine types. The ATL P-38J with W.I. can already hit the performance numbers it would otherwise gain from using Grade 150 fuel. This will have the advantage of decreasing the lead-fouling issues associated with AN-44-1 fuel and allow P-38 FGs--with their higher fuel requirements--to use less expensive and more readily available 100/130/fuel.
Most likely just using a stronger steel alloy and/or look into production methods (are they forged or cast con rods?). That should allow up to 80"Hg with 104/150 fuel and W.I. in the ATL P-38J.
The knife-and-fork gives other benefits, though, especially for the P-38 which used "handed" engines as it allowed the block and heads to be perfectly symmetrical which allowed ground crews to easily change engines between sides of the A/C.
That looks like a fuel distribution issue, to me. Otherwise, why only one failure, & the same one on either side? Could be there's oiling trouble, too.... Don't blame the conrods; if they were at fault, there'd be other failures, & they'd have been seen before now.
I'd check the oil for shavings & see if the cylinder wall's scored, first, but I'll bet that's not a problem, either, for the same reason.
I'd test an engine to destruction on the bench, with EGT & pyros in the heads, to see what's going on in the combustion chamber. I'll bet you're getting an over-lean condition or something that's creating a "bang" that's breaking rods, & the higher boost is bringing it out. The symmetry of the failure is your proof. Bad rods wouldn't be breaking symmetrically.
So they may have to redesign the intake manifolds again as the higher boost is more vulnerable to any deficiencies in the uniformity of the charge. This is becoming a good argument for fuel injection but of course that's too late for the WW2 P-38 engines.
Rath wrote:
The former quite a bit more than the latter actually. The A-10 has issues firing at neutral or positive angles of attack. ie: they stall from the recoil.
A-10s would 'bag' a few overconfident fighter jocks every exercise by 'dangling' a lone A-10 around the terrain too high to use it for cover. When the fighters would roll in for an attack run with guns the OTHER A-10(s) would pull up out of the clutter and fire off a VERY short burst, stall, roll off a wing and dive to recover. This all being 'simulated' (aka no one really shot anything) the computers would calculate maybe one or two rounds of 'burst' hit the target. One or two 30mm round is about all you need to at least generate a 'mission' kill but please note the circumstances.
While 'fun' to do in training and exercises no A-10 pilot was ever going to do this in the 'real' world because the 'bait' would be hit by a missile and no A-10 can fight an actual fighter and win.
Archibald wrote:
IF it hits them that is. What is going to REALLY freak them out is getting lots and lots of 'hits' of their own and seeing the A-10 fly out of it with no apparent damage.
Phx1138 wrote:
Well they DID engage the two strafing that boat but THAT was kind of cheesy as the F-14's would have had a heck of a time keeping up with the zero's in turning combat. (I seem to recall one was hit with missiles which as an ammo troop got my back up. The Sidewinder wasn't sensitive enough at the time to lock onto a piston engine and they were far to close to use the AIM7s. The 20mm rounds would have shredded the zero very nicely but again getting lined up would be very tough with the F-14 on the edge of stalling. Going supersonic in a close pass would have done the trick)
Butchpdf wrote:
[/quote]If you are going to isot a squadron or two of the A-10s, why not up the game, and have them escorting a flight of AC-130s.. Oh the irony the Japanese strike force chewed up by upity transports.[/quote]
A-10s don't do escort duty for obvious reasons And pretty much nobody does 'flights' or 'squadrons' anymore either. You may see pairs or some such up to about a half dozen in the same local 'area' on ferry flights, but even in hostile airspace formations are pretty lose in the missile age.
Worse, (to my military senses anyway) is nobody ever picks the 'right' weapons, (which makes sense as it's not much of a story the OTWA) to use.
The "A" in both A-10 and AC-130 indicates an "attack' aircraft not a fighter or aircraft designed to engage in air-to-air conflict. Could either one do some significant 'damage' to the Japanese "Strike Force*" if they engaged? Yep, but it would be limited due to the number of targets, disparity in flight envelopes and lack of dedicated air-to-air training and design.
(*Depends on which "Strike Force" we're talking as well. See below)
Sure the a single GAU-8 30mm round, even a 'dummy' or practice round which is BTW all that's carried unless they are actually headed to engage a REAL target, (range or actual) is going to destroy any WWII aircraft IF it hits. But getting that hit is critical and you only carry about 1300 rounds and to hit an maneuvering target you're looking at burst of at least 50 rounds to generate a 'decent' chance of a hit.
1300/50= 26 'bursts and a possible 26 targets downed. Note above I pointed out it would be 'frustrating' to see the A-10 flying through everything the zero put out and flying out "no apparent damage" but it is still being hit and isn't armored everywhere and eventually with enough zeros swarming it someone's going to get luck...
The AC-130s actually worse because it IS a 'transport' aircraft, (the zero actually is faster at about 332mph compared to 300mph both with a 'combat' load) it's not really armored. (And to answer the main question anyone approaching from the 'right' side is safe as the guns are only on the left) It's not that maneuverable and will get swarmed as well. Even 'just' attacking Kito Butai, assuming the CAP doesn't get the Specter, you have to be at around 10,000ft to fire for effect and while the 105 will do some damage you only carry about 40 rounds total. Even the very latest mods only carry a half dozen Hellfire's or Griffins and it will take several to cause significant damage to a carrier. The 20mm/25mm/40mm guns are just going to be doing surface and crew damage.
And these things are NOT invisible or undetectable to the enemy either. The Japanese will SEE these coming at them and maneuver themselves which means 'fighters' moving to intercept and attack aircraft moving away which makes targeting even harder.
And I probably should mention that while "Final Countdown" had flaws most people miss that there were some VERY serious questions asked that the scenario never (luckily) got answered because the "Nimitz" got pulled back to the present.
The Captain was correct in that the US not having been attacked 'yet' his technical and legal "answer" should have been to present himself and the ship to the "local" authority and submit to the existing US Navel chain of command.
The idea of intercepting the "Strike Force" and giving them the option to call it off, (they wouldn't have) was pretty correct as it would have disrupted the attack itself, (even if they didn't actually destroy the attacking force keep in mind HALF that 'package' was headed towards Kito Butai and once things kicked off there WAS enough firepower involved to put every single ship on the bottom) and ensured the Japanese threat was stopped dead in its tracks. The problem is what comes after because you're not going to "Win in the Pacific, then nuke some Nazis & some Commies & declare FDR God" all that easy.
It's "Zipang" (https://en.wikipedia.org/wiki/Zipang_(manga))* on steroids and not something you could reasonably resolve in a movie length feature. Sure the 'initial' high from giving a beat down is great but the long-haul is the REAL story.
(What's the 'right' weapon is very dependent on the scenario. For taking out the Japanese air attack on Pearl Harbor the "Final Countdown" is probably the best, though rather than configure for modern air-to-air I'd see using 'slick' F-14 to run multiple supersonic passes around the formations. That would be enough to disrupt and destroy the integrity of the overall attack and you need to save ammo to run the long-game)
Apparently the Japanese did it before "Final Countdown" as well: https://en.wikipedia.org/wiki/G.I._Samurai, (remake: https://en.wikipedia.org/wiki/Samurai_Commando:_Mission_1549, which looks damn interesting AND ties things up nicely )
Randy
The former quite a bit more than the latter actually. The A-10 has issues firing at neutral or positive angles of attack. ie: they stall from the recoil.
A-10s would 'bag' a few overconfident fighter jocks every exercise by 'dangling' a lone A-10 around the terrain too high to use it for cover. When the fighters would roll in for an attack run with guns the OTHER A-10(s) would pull up out of the clutter and fire off a VERY short burst, stall, roll off a wing and dive to recover. This all being 'simulated' (aka no one really shot anything) the computers would calculate maybe one or two rounds of 'burst' hit the target. One or two 30mm round is about all you need to at least generate a 'mission' kill but please note the circumstances.
While 'fun' to do in training and exercises no A-10 pilot was ever going to do this in the 'real' world because the 'bait' would be hit by a missile and no A-10 can fight an actual fighter and win.
Archibald wrote:
IF it hits them that is. What is going to REALLY freak them out is getting lots and lots of 'hits' of their own and seeing the A-10 fly out of it with no apparent damage.
Phx1138 wrote:
Yep. 1980, IIRC. They wouldn't let 'em actually engage...
Well they DID engage the two strafing that boat but THAT was kind of cheesy as the F-14's would have had a heck of a time keeping up with the zero's in turning combat. (I seem to recall one was hit with missiles which as an ammo troop got my back up. The Sidewinder wasn't sensitive enough at the time to lock onto a piston engine and they were far to close to use the AIM7s. The 20mm rounds would have shredded the zero very nicely but again getting lined up would be very tough with the F-14 on the edge of stalling. Going supersonic in a close pass would have done the trick)
Butchpdf wrote:
[/quote]If you are going to isot a squadron or two of the A-10s, why not up the game, and have them escorting a flight of AC-130s.. Oh the irony the Japanese strike force chewed up by upity transports.[/quote]
A-10s don't do escort duty for obvious reasons
And pretty much nobody does 'flights' or 'squadrons' anymore either. You may see pairs or some such up to about a half dozen in the same local 'area' on ferry flights, but even in hostile airspace formations are pretty lose in the missile age.Worse, (to my military senses anyway) is nobody ever picks the 'right' weapons, (which makes sense as it's not much of a story the OTWA) to use.
The "A" in both A-10 and AC-130 indicates an "attack' aircraft not a fighter or aircraft designed to engage in air-to-air conflict. Could either one do some significant 'damage' to the Japanese "Strike Force*" if they engaged? Yep, but it would be limited due to the number of targets, disparity in flight envelopes and lack of dedicated air-to-air training and design.
(*Depends on which "Strike Force" we're talking as well. See below)
Sure the a single GAU-8 30mm round, even a 'dummy' or practice round which is BTW all that's carried unless they are actually headed to engage a REAL target, (range or actual) is going to destroy any WWII aircraft IF it hits. But getting that hit is critical and you only carry about 1300 rounds and to hit an maneuvering target you're looking at burst of at least 50 rounds to generate a 'decent' chance of a hit.
1300/50= 26 'bursts and a possible 26 targets downed. Note above I pointed out it would be 'frustrating' to see the A-10 flying through everything the zero put out and flying out "no apparent damage" but it is still being hit and isn't armored everywhere and eventually with enough zeros swarming it someone's going to get luck...
The AC-130s actually worse because it IS a 'transport' aircraft, (the zero actually is faster at about 332mph compared to 300mph both with a 'combat' load) it's not really armored. (And to answer the main question anyone approaching from the 'right' side is safe as the guns are only on the left) It's not that maneuverable and will get swarmed as well. Even 'just' attacking Kito Butai, assuming the CAP doesn't get the Specter, you have to be at around 10,000ft to fire for effect and while the 105 will do some damage you only carry about 40 rounds total. Even the very latest mods only carry a half dozen Hellfire's or Griffins and it will take several to cause significant damage to a carrier. The 20mm/25mm/40mm guns are just going to be doing surface and crew damage.
And these things are NOT invisible or undetectable to the enemy either. The Japanese will SEE these coming at them and maneuver themselves which means 'fighters' moving to intercept and attack aircraft moving away which makes targeting even harder.
And I probably should mention that while "Final Countdown" had flaws most people miss that there were some VERY serious questions asked that the scenario never (luckily) got answered because the "Nimitz" got pulled back to the present.
The Captain was correct in that the US not having been attacked 'yet' his technical and legal "answer" should have been to present himself and the ship to the "local" authority and submit to the existing US Navel chain of command.
The idea of intercepting the "Strike Force" and giving them the option to call it off, (they wouldn't have) was pretty correct as it would have disrupted the attack itself, (even if they didn't actually destroy the attacking force keep in mind HALF that 'package' was headed towards Kito Butai and once things kicked off there WAS enough firepower involved to put every single ship on the bottom) and ensured the Japanese threat was stopped dead in its tracks. The problem is what comes after because you're not going to "Win in the Pacific, then nuke some Nazis & some Commies & declare FDR God" all that easy.
It's "Zipang" (https://en.wikipedia.org/wiki/Zipang_(manga))* on steroids and not something you could reasonably resolve in a movie length feature. Sure the 'initial' high from giving a beat down is great but the long-haul is the REAL story.
(What's the 'right' weapon is very dependent on the scenario. For taking out the Japanese air attack on Pearl Harbor the "Final Countdown" is probably the best, though rather than configure for modern air-to-air I'd see using 'slick' F-14 to run multiple supersonic passes around the formations. That would be enough to disrupt and destroy the integrity of the overall attack and you need to save ammo to run the long-game)
Apparently the Japanese did it before "Final Countdown" as well: https://en.wikipedia.org/wiki/G.I._Samurai, (remake: https://en.wikipedia.org/wiki/Samurai_Commando:_Mission_1549, which looks damn interesting AND ties things up nicely
)Randy
Actually, AIUI, this isn't a manifold design issue, it's a problem with the fuel system (the manifold is just a channel; what matters is how much fuel is getting to each cylinder): fix with changes in fuel pressure, carbs (more of them) or carb jetting (more fuel flow, or better mixture), maybe ignition timing & spark plugs (heat rating; with dual plugs, the "unburned" issue is moot); I'm getting away from the familiar, here. I'm also thinking water injection in the alt-V1710s affects the prospects of this kind of problem, with charge cooling in the head, but, again, it's a distribution issue.
The source of the trouble would be found on the bench (which, in this situation, means EverKing's research...
{Sorry, boss, this one's on you.}); or you can handwave it & say the problem was found & fixed after bench testing, & just blame the carbs. Come to think of it, EverKing, can you find out which carbs the engines that broke were using? If later engines were running more boost without rod failures, & they had different carbs spec'd, that'd be proof enough for me. (I wouldn't demand to know, if you do; if you said there was a spec change to the new model, to cure this issue, I'll take your word on it.)
Myself, I was picturing the GAU-8 against the CVs, not the Zekes.
Not so many, I don't think: one into the bridge & take out the command staff, one or two in the elevators... 12 expended? 18? Maybe 24, allowing for a "not Tom Clancy" combat environment, where some miss or fail to function correctly...
I don't recall what the date was; had Nimitz arrived on 6 December local, IIRC, Nagumo had orders to withdraw if detected within 24h of scheduled launch.
No? Nimitz, by herself, could deliver more firepower than the Kido Butai, even without resort to her nukes; save those for Germany.
There's a page worth of google entries discrediting this remark, and the loadout is 1150 rounds, firing at 50 rps in the first second, 70 in the second second. The recoil is reported as about equal to one engine, and they might slow down by 3 kts from a burst. Unless they were flying 2 kts or less above the stall when firing, they're not stalling. The A-10 has scored a guns air kill.
Again, I apologize for the delay as this next chapter was planned to be up last week. Just to let you all in on why my time for this has decreased (without getting too much into my personal life) I have been thrown a handful of new systems projects at work which has been dominating my thoughts of late and at home my wife--who was a Surrogate--recently delivered and we have been playing host to the parents, who are international.
No worries. The test engines used the PD-12K7 or K8 carbs so I am thinking this fuel/air flow issue can be fairly easily solved on the ATL F29 engines since they are moving up to PT-13's. I am not sure if it was a symmetrical failure as they specify the original failure occurred at either 3L or 3R, not both. Add to that the repeated comments that there was no evidence of pre-ignition in the cylinders and it looks like it may just have been a bad con.rod. Possibly a bad forge with a line of impurities which hair-lined and failed under the increased pressure.{Sorry, boss, this one's on you.
That's fine. Real life should always take precedence. And I hope your wife is doing fine. And congratulations to all the new parents.
Ch.27 - Flight Tests P-38H-15-LO (4 Feb 1944)
Flight Test Engineering Branch
Memo Report No. Eng-47-1706-A
4 February 1944
FLIGHT TESTS
OF A P-38H AIRPLANE [42-67869, P-38H-15-LO]
I Introduction
Flight tests have been conducted at Wright Field on the P-38H-15-LO Airplane, AAF, No. 42-67869, at the request of the Fighter Branch, Experimental Engineering Division. These tests were made on this airplane primarily to obtain comparative performance data with similar tests on a P-47D-10, a P-39Q-5 and a P-51B airplane. The performance should be that of a typical production model as it was selected at random from airplanes which had been delivered from the factory. From 2 December 1943 to 21 January 1944 approximately 30 hours were flown on this airplane by Capt. G. E. Lundquist, Capt F. C. Bretcher, and Capt J. W. Williams.
II Summary
The P-38H is designed as a high altitude fighter interceptor. This airplane has a fast rate of climb and performs well at high altitude, however, caution must be exercised when performing power-on dives from high altitude to keep the airplane below posted dive limits. These airspeed limitations are sufficiently high for a fighter aircraft but if exceeded may lead to progressively nose-heavy attitude and loss of pitch control and are definitely objectionable and hazardous from a combat viewpoint. The stability about all axis is good, the radius of turn is fairly large for a fighter and the rate of roll is fair at medium speeds, but slow at high speeds because of heavy aileron forces. The single engine operation, visibility on the ground and in the air and cockpit layout is good.
High speed and climb performance have been completed on this airplane at a take-off weight of 17,567 lb. This loading corresponds to the average P-38 combat weight with full oil, 420 gallons of fuel and specified armament and ammunition.
The principal results are as follows:
Max speed at critical altitude, 25,800'
(60.0" Hg. Man. Pr. & 3000 rpm) = 430.0 mph
Max speed at sea level
(60.0" Hg. Man. Pr. & 3000 rpm) = 361 mph
Rate of climb at sea level
(60.0" Hg. Man. Pr. & 3000 rpm) = 3955'/min.
Rate of climb at critical altitude, 23,400 ft.
(60.0" Hg. Man. Pr. & 3000 rpm) = 2790'/min.
Time to climb to critical altitude, 23,400 ft.
(60.0" Hg. Man. Pr. & 3000 rpm) = 6.65 min.
Service Ceiling = 40,000'
III Condition of Aircraft Relative to Tests
A. The airplane was equipped with wing racks, otherwise the configuration was normal with all flights at a gross weight at take-off of 17,567 pounds with the c.g at 23.75% m.a.c., gear down; and 27.5% m.a.c. , gear up. Gross weight included 420 gallons of fuel, 26 gallons of oil, 457 lbs. of ballast for ammunition, and automatic observer, complete radio equipment and antenna, and 200 pounds for the pilot. All items effecting the drag of the airplane may be seen in the photographs which are included at the end of the report.
B. The airplane was equipped with Allison V-1710-89 & 91 engines, type B-33 turbo superchargers with A-13B turbo regulators and Curtiss Electric three blade propellers, blade design numbers 89303-18 and 88996-18, left and right respectively. All power figures are based on a power curve from Eng. Spec. No. 162, dated 30 November 1942.
C. The armament consisted of four 50 caliber machine guns and one 20 mm. cannon in the nose with 457.5 lb. of ballast corresponding to the weight of 1200 rounds of 50 caliber and 150 rounds of 20 mm. ammunition.
D. All flights were made with flaps neutral, gear up, air filter off, intercooler, coolant and oil shutters automatic, and mixture automatic rich unless otherwise stated.
IV Flight Characteristics
A. Taxiing and Ground Handling
The airplane is easy to taxi and vision is excellent. Response to throttles in turning is good and brakes are readily applied for all positions of the rudder making directional control easy.
B. Take-off
The take-off characteristics of the P-38H are normal for a tricycle gear airplane except for the absence of any noticeable torque effect due to the opposite rotating propellers. The airplane takes off after a short ground run and has a steep initial angle of climb. Vision during take-off and climb is good.
C. Stability
The airplane has good longitudinal, directional and lateral stability at all normal speeds, however, there is a slight tendency to hunt directionally in rough air or when flown with external wing tanks. All stability tests were run with full ammunition and a c.g. of 27.5%, well ahead of the c.g. of 28.5% which was the maximum allowable rearward c.g. position at the time of the test. Recent tests on other P-38H's show that it is permissible to move the c.g. back to 32% of the m.a.c.
D. Trim and Balance
The airplane is readily trimmed for all normal flight conditions. Due to the opposite rotating propellers, rudder and aileron trim tab settings do not require adjustment with changes in speed and power. The airplane becomes very noticeably nose heavy when flaps and landing gear are extended, but this change in balance can be easily corrected by use of elevator trim tab.
E. Controllability
Handling qualities of this airplane are generally good. Control forces are moderate and controls are responsive to a high degree at all normal speeds. However, at extremely high speeds beyond the P-38's dive speed limits, the airplane tends to become rapidly nose heavy and elevator effectiveness decreases, making it difficult to pull out.
F. Maneuverability
The airplane is highly maneuverable considering the high wing loading. It has a fairly large radius of turn for a fighter but this is greatly improved by the use of maneuvering flaps. Response to controls in rolls, loops, immelmans is good and these maneuvers are easily executed.
G. Stalling Characteristics
In either power on or power off stalls with flaps and landing gear up the airplane stalls straight forward in a well controlled stall. With flaps and gear down there is a slight tendency for a wing to drop, but there is no tendency to spin. Ailerons remain effective giving adequate control throughout the stall. Warning of the approaching stall is given by a noticeable buffeting and shaking of the airplane and controls. See Part IV F. for stalling speeds for different configurations.
H. Spinning Characteristics
No spin tests were performed.
I. Diving Characteristics
At extremely high speeds in dives the airplane rapidly becomes nose heavy and starts to buffet as if it were about to stall. If this condition is allowed to develop the nose heavy condition becomes more pronounced making the pull out difficult.
J. Single Engine Operation
The airplane has excellent single engine performance. The indicated speed for best climb on one engine is approximately 145 mph and the minimum indicated airspeed at which control can be maintained at rated power is 110 mph. Normal single engine procedure is used.
K. High Altitude Trials
The general operation of the airplane and all controls at high altitudes and low temperatures is satisfactory. However, care must be taken when performing full power-on dives from high altitude as the airplane will rapidly accelerate to its dive speed limit (see paragraph I).
L. Approach and Landing
The airplane has a normal glide angle and landing technique used is similar to that for airplanes with tailwheels. Vision is excellent on the approach and landing and the tricycle gear reduces the hazards from landing in a cross wind.
M. Night Flying
The cockpit lighting in general is good. Direct or reflected glare from the instrument board lights is not objectionable, however, considerable glare is caused by the cockpit lamps. A retractable landing light is mounted under the left wing and provides adequate lighting for landing, but causes considerable buffeting when fully extended. This light has been replaced with a streamlined leading edge light in new P-38H models and is not cause for concern.
N. Noise and Vibration Level Tests at Crew Stations
The noise level of the airplane is low and is not objectionable at any time.
O. Pilot's report on vision and cockpit layout
The vision from the cockpit is good except to the side and down where the engine nacelles interfere. All controls in the cockpit are easily accessible to the pilot and in general the cockpit layout is satisfactory.
V Ship Board Tests
No tests performed.
VI Performance Data (War Emergency Power, 60.0" Hg. Man. Press. & 3000 rpm and 17,567 lb.)
A. Airspeed indicator and altimeter calibration
Airspeed indiator error with Kollsman type D-2 ship's standard pitot head located 8' 1-1/2" inboard left wing tip, 14-5/16" below the wing with the static holes 25-3/4" aft of the leading edge of the wing.
B. High Speed (see Curves)
High speeds in level flight at 3000 rpm, oil shutters flush, coolant shutters automatic, and intercooler shutters closed.
C. Cruise Data
Cruising speed at 11,850 feet with mixture as specified, oil shutters flush, coolant shutters automatic, and intercooler closed. This cruise data was obtained on the original right engine and the new left engine and is not comparable to the other reported (see part VI. Sec. G) speed data.
D. Climb Data
Climb performance at 3000 rpm with oil and coolant flaps automatic, and intercooler shutters wide open.
E. Cooling Flaps Tests
The average temperatures maintained by the thermostatic controls on the oil and coolant flaps were 85°C and 105°C respectively; therefore, all performance was corrected to flap positions that would maintain these temperatures on a standard day with the exception of the oil flaps, which were corrected to the flush position for level flight.
No standard Air Corps cooling tests were made, however, from all indications the airplane will meet the requirements (125°C coolant temperature and 95°C oil temperature) in both level flight and climb with the exception that the oil temperature would be critical in climb above 35000' on an army hot day.
(1) Oil and coolant flap calibrations in level flight at 5000 feet altitude with 50" Hg. manifold pressure and 3000 rpm.
F. Stalling Speeds
G. Remarks
The high speeds reported were obtained with the original engines in the airplane. The left engine failed during a critical altitude power run and after replacement several high speed checks were made. The high speeds obtained with this new combination of engines were approximately 7 mph slower than on the original combination.
Climb performance was obtained with the original right engine and the new left engine. The right engine also failed during a critical altitude power run and high speed checks made after this engine was replaced showed the airplane to be approximately 5 mph slower than the original combination. The high speeds obtained on the two original engines was reported because more speed data was available, less time was on the airplane and engines, and the surfaces of the airplane were less worn at the time this data was obtained.
It may be stated here that the performance reported cannot be obtained unless strict attention is given to maintaining a minimum duct leakage by keeping the entire duct system tight.
VII Curves
VIII Conclusions
It is concluded that the performance reported is representative of the P-38H airplane, as the subject airplane was flown at combat weight and was also selected at random from P-38H airplanes delivered from the factory.
IX Recommendations
It is recommended that this method of selection of airplanes for flight test be adopted, and that hereafter all airplanes be test flown at the specified combat weight.
X General Dimension and Photographs
A. P-38H Dimensions
Span 52' 0"
Length 37'10"
Height 12'10"
Tread 16' 6"
Wing Area 344 sq. ft.
Memo Report No. Eng-47-1706-A
4 February 1944
FLIGHT TESTS
OF A P-38H AIRPLANE [42-67869, P-38H-15-LO]
I Introduction
Flight tests have been conducted at Wright Field on the P-38H-15-LO Airplane, AAF, No. 42-67869, at the request of the Fighter Branch, Experimental Engineering Division. These tests were made on this airplane primarily to obtain comparative performance data with similar tests on a P-47D-10, a P-39Q-5 and a P-51B airplane. The performance should be that of a typical production model as it was selected at random from airplanes which had been delivered from the factory. From 2 December 1943 to 21 January 1944 approximately 30 hours were flown on this airplane by Capt. G. E. Lundquist, Capt F. C. Bretcher, and Capt J. W. Williams.
II Summary
The P-38H is designed as a high altitude fighter interceptor. This airplane has a fast rate of climb and performs well at high altitude, however, caution must be exercised when performing power-on dives from high altitude to keep the airplane below posted dive limits. These airspeed limitations are sufficiently high for a fighter aircraft but if exceeded may lead to progressively nose-heavy attitude and loss of pitch control and are definitely objectionable and hazardous from a combat viewpoint. The stability about all axis is good, the radius of turn is fairly large for a fighter and the rate of roll is fair at medium speeds, but slow at high speeds because of heavy aileron forces. The single engine operation, visibility on the ground and in the air and cockpit layout is good.
High speed and climb performance have been completed on this airplane at a take-off weight of 17,567 lb. This loading corresponds to the average P-38 combat weight with full oil, 420 gallons of fuel and specified armament and ammunition.
The principal results are as follows:
Max speed at critical altitude, 25,800'
(60.0" Hg. Man. Pr. & 3000 rpm) = 430.0 mph
Max speed at sea level
(60.0" Hg. Man. Pr. & 3000 rpm) = 361 mph
Rate of climb at sea level
(60.0" Hg. Man. Pr. & 3000 rpm) = 3955'/min.
Rate of climb at critical altitude, 23,400 ft.
(60.0" Hg. Man. Pr. & 3000 rpm) = 2790'/min.
Time to climb to critical altitude, 23,400 ft.
(60.0" Hg. Man. Pr. & 3000 rpm) = 6.65 min.
Service Ceiling = 40,000'
III Condition of Aircraft Relative to Tests
A. The airplane was equipped with wing racks, otherwise the configuration was normal with all flights at a gross weight at take-off of 17,567 pounds with the c.g at 23.75% m.a.c., gear down; and 27.5% m.a.c. , gear up. Gross weight included 420 gallons of fuel, 26 gallons of oil, 457 lbs. of ballast for ammunition, and automatic observer, complete radio equipment and antenna, and 200 pounds for the pilot. All items effecting the drag of the airplane may be seen in the photographs which are included at the end of the report.
B. The airplane was equipped with Allison V-1710-89 & 91 engines, type B-33 turbo superchargers with A-13B turbo regulators and Curtiss Electric three blade propellers, blade design numbers 89303-18 and 88996-18, left and right respectively. All power figures are based on a power curve from Eng. Spec. No. 162, dated 30 November 1942.
C. The armament consisted of four 50 caliber machine guns and one 20 mm. cannon in the nose with 457.5 lb. of ballast corresponding to the weight of 1200 rounds of 50 caliber and 150 rounds of 20 mm. ammunition.
D. All flights were made with flaps neutral, gear up, air filter off, intercooler, coolant and oil shutters automatic, and mixture automatic rich unless otherwise stated.
IV Flight Characteristics
A. Taxiing and Ground Handling
The airplane is easy to taxi and vision is excellent. Response to throttles in turning is good and brakes are readily applied for all positions of the rudder making directional control easy.
B. Take-off
The take-off characteristics of the P-38H are normal for a tricycle gear airplane except for the absence of any noticeable torque effect due to the opposite rotating propellers. The airplane takes off after a short ground run and has a steep initial angle of climb. Vision during take-off and climb is good.
C. Stability
The airplane has good longitudinal, directional and lateral stability at all normal speeds, however, there is a slight tendency to hunt directionally in rough air or when flown with external wing tanks. All stability tests were run with full ammunition and a c.g. of 27.5%, well ahead of the c.g. of 28.5% which was the maximum allowable rearward c.g. position at the time of the test. Recent tests on other P-38H's show that it is permissible to move the c.g. back to 32% of the m.a.c.
D. Trim and Balance
The airplane is readily trimmed for all normal flight conditions. Due to the opposite rotating propellers, rudder and aileron trim tab settings do not require adjustment with changes in speed and power. The airplane becomes very noticeably nose heavy when flaps and landing gear are extended, but this change in balance can be easily corrected by use of elevator trim tab.
E. Controllability
Handling qualities of this airplane are generally good. Control forces are moderate and controls are responsive to a high degree at all normal speeds. However, at extremely high speeds beyond the P-38's dive speed limits, the airplane tends to become rapidly nose heavy and elevator effectiveness decreases, making it difficult to pull out.
F. Maneuverability
The airplane is highly maneuverable considering the high wing loading. It has a fairly large radius of turn for a fighter but this is greatly improved by the use of maneuvering flaps. Response to controls in rolls, loops, immelmans is good and these maneuvers are easily executed.
G. Stalling Characteristics
In either power on or power off stalls with flaps and landing gear up the airplane stalls straight forward in a well controlled stall. With flaps and gear down there is a slight tendency for a wing to drop, but there is no tendency to spin. Ailerons remain effective giving adequate control throughout the stall. Warning of the approaching stall is given by a noticeable buffeting and shaking of the airplane and controls. See Part IV F. for stalling speeds for different configurations.
H. Spinning Characteristics
No spin tests were performed.
I. Diving Characteristics
At extremely high speeds in dives the airplane rapidly becomes nose heavy and starts to buffet as if it were about to stall. If this condition is allowed to develop the nose heavy condition becomes more pronounced making the pull out difficult.
J. Single Engine Operation
The airplane has excellent single engine performance. The indicated speed for best climb on one engine is approximately 145 mph and the minimum indicated airspeed at which control can be maintained at rated power is 110 mph. Normal single engine procedure is used.
K. High Altitude Trials
The general operation of the airplane and all controls at high altitudes and low temperatures is satisfactory. However, care must be taken when performing full power-on dives from high altitude as the airplane will rapidly accelerate to its dive speed limit (see paragraph I).
L. Approach and Landing
The airplane has a normal glide angle and landing technique used is similar to that for airplanes with tailwheels. Vision is excellent on the approach and landing and the tricycle gear reduces the hazards from landing in a cross wind.
M. Night Flying
The cockpit lighting in general is good. Direct or reflected glare from the instrument board lights is not objectionable, however, considerable glare is caused by the cockpit lamps. A retractable landing light is mounted under the left wing and provides adequate lighting for landing, but causes considerable buffeting when fully extended. This light has been replaced with a streamlined leading edge light in new P-38H models and is not cause for concern.
N. Noise and Vibration Level Tests at Crew Stations
The noise level of the airplane is low and is not objectionable at any time.
O. Pilot's report on vision and cockpit layout
The vision from the cockpit is good except to the side and down where the engine nacelles interfere. All controls in the cockpit are easily accessible to the pilot and in general the cockpit layout is satisfactory.
V Ship Board Tests
No tests performed.
VI Performance Data (War Emergency Power, 60.0" Hg. Man. Press. & 3000 rpm and 17,567 lb.)
A. Airspeed indicator and altimeter calibration
Airspeed indiator error with Kollsman type D-2 ship's standard pitot head located 8' 1-1/2" inboard left wing tip, 14-5/16" below the wing with the static holes 25-3/4" aft of the leading edge of the wing.
B. High Speed (see Curves)
High speeds in level flight at 3000 rpm, oil shutters flush, coolant shutters automatic, and intercooler shutters closed.
C. Cruise Data
Cruising speed at 11,850 feet with mixture as specified, oil shutters flush, coolant shutters automatic, and intercooler closed. This cruise data was obtained on the original right engine and the new left engine and is not comparable to the other reported (see part VI. Sec. G) speed data.
D. Climb Data
Climb performance at 3000 rpm with oil and coolant flaps automatic, and intercooler shutters wide open.
E. Cooling Flaps Tests
The average temperatures maintained by the thermostatic controls on the oil and coolant flaps were 85°C and 105°C respectively; therefore, all performance was corrected to flap positions that would maintain these temperatures on a standard day with the exception of the oil flaps, which were corrected to the flush position for level flight.
No standard Air Corps cooling tests were made, however, from all indications the airplane will meet the requirements (125°C coolant temperature and 95°C oil temperature) in both level flight and climb with the exception that the oil temperature would be critical in climb above 35000' on an army hot day.
(1) Oil and coolant flap calibrations in level flight at 5000 feet altitude with 50" Hg. manifold pressure and 3000 rpm.
F. Stalling Speeds
G. Remarks
The high speeds reported were obtained with the original engines in the airplane. The left engine failed during a critical altitude power run and after replacement several high speed checks were made. The high speeds obtained with this new combination of engines were approximately 7 mph slower than on the original combination.
Climb performance was obtained with the original right engine and the new left engine. The right engine also failed during a critical altitude power run and high speed checks made after this engine was replaced showed the airplane to be approximately 5 mph slower than the original combination. The high speeds obtained on the two original engines was reported because more speed data was available, less time was on the airplane and engines, and the surfaces of the airplane were less worn at the time this data was obtained.
It may be stated here that the performance reported cannot be obtained unless strict attention is given to maintaining a minimum duct leakage by keeping the entire duct system tight.
VII Curves
VIII Conclusions
It is concluded that the performance reported is representative of the P-38H airplane, as the subject airplane was flown at combat weight and was also selected at random from P-38H airplanes delivered from the factory.
IX Recommendations
It is recommended that this method of selection of airplanes for flight test be adopted, and that hereafter all airplanes be test flown at the specified combat weight.
X General Dimension and Photographs
A. P-38H Dimensions
Span 52' 0"
Length 37'10"
Height 12'10"
Tread 16' 6"
Wing Area 344 sq. ft.
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A few comments/notes on some of the test data used in the above post...
For the True Airspeed, I used the same methodology I used in previous chapters. I.E. Take the original TAS at Altitude, apply a standard percent increase adjusted for Air Density (due to better aerodynamics), and adjust for Weight. I know it is not perfect, but I gives us a close-enough approximation of what I think this airplane could do.
For the Rate of Climb, I finally tackled some alterations to the original data. I first calculated the angle of the climb from the OTL charts at each data point, then I used the the same speed at altitude transform to get the base TAS of the climb and calculated a new base Rate of Climb by using this new TAS at the OTL angle of climb. After that, I realized that the ATL A/C is 970 lbs. heavier (Gross at Take-Off) than the OTL so I needed to reduce the RoC for the increased weight. To do this I used the ATL Base RoC and the OTL Gross Weight to calculate the Excess Thrust Horsepower (ETHP) of the ATL plane if it had been at the same Gross Weight as the OTL. Using that ETHP and the ATL TAS I was able to calculate the new RoC by using the Vc=ETHP*(33000/W) equation.
I used a similar method to calculate new stalling speeds for the ATL P-38H but applied a simple estimation of lift (due to increased wing area). Using the lower Stall Speed from this estimation (about 3.8% improvement) I then calculate the K value of the airplane at the OTL Gross Weight and used this K value to calculate the actual Stall Speed at the increased Gross Weight (for the most part it worked out to be about 1 MPH higher than OTL...all that work for 1 measly MPH).
The increase in Wing Area (from 328 sq. ft. to 344 sq. ft) is a rough calculation of the extra 8.15 sq.ft. / side added by the 20% Chord Extension in the center section. (EDIT: Re-calculated the number and the increased wing area is only about 16 sq. ft. which does not fully make up for the increased weight of the A/C over ATL (Wingloading up by about 1 lb/sq.ft.) )
I kept the OTL numbers for Oil and Coolant positions but changed the wording from "Shutters" to "Flaps" to reflect the re-design. I am sure the opening sized are incorrect considering the design but I, frankly, didn't even know where to start to get actual design numbers for the ATL P-38.
EDIT: I forgot to talk about how I calculated the Time to Climb. I broke the Rate of Climb down to 200' increments using MS Excel's LINEST function referencing the calculated ATL RoC (as described above) to get the formula constants (a,b,c,d) for a fourth degree polynomial (ax^3+bx^2+cx+d). I then figured the timelapse between each 200' and its predecessor (e.g. 200' - 400', 400' - 600', etc.) and used a simple sum to add them up for each altitude. Again, not perfectly accurate, but plenty close enough for our needs (I tested it using the OTL number and got with a few points for each altitude).
For the True Airspeed, I used the same methodology I used in previous chapters. I.E. Take the original TAS at Altitude, apply a standard percent increase adjusted for Air Density (due to better aerodynamics), and adjust for Weight. I know it is not perfect, but I gives us a close-enough approximation of what I think this airplane could do.
For the Rate of Climb, I finally tackled some alterations to the original data. I first calculated the angle of the climb from the OTL charts at each data point, then I used the the same speed at altitude transform to get the base TAS of the climb and calculated a new base Rate of Climb by using this new TAS at the OTL angle of climb. After that, I realized that the ATL A/C is 970 lbs. heavier (Gross at Take-Off) than the OTL so I needed to reduce the RoC for the increased weight. To do this I used the ATL Base RoC and the OTL Gross Weight to calculate the Excess Thrust Horsepower (ETHP) of the ATL plane if it had been at the same Gross Weight as the OTL. Using that ETHP and the ATL TAS I was able to calculate the new RoC by using the Vc=ETHP*(33000/W) equation.
I used a similar method to calculate new stalling speeds for the ATL P-38H but applied a simple estimation of lift (due to increased wing area). Using the lower Stall Speed from this estimation (about 3.8% improvement) I then calculate the K value of the airplane at the OTL Gross Weight and used this K value to calculate the actual Stall Speed at the increased Gross Weight (for the most part it worked out to be about 1 MPH higher than OTL...all that work for 1 measly MPH).
The increase in Wing Area (from 328 sq. ft. to 344 sq. ft) is a rough calculation of the extra 8.15 sq.ft. / side added by the 20% Chord Extension in the center section. (EDIT: Re-calculated the number and the increased wing area is only about 16 sq. ft. which does not fully make up for the increased weight of the A/C over ATL (Wingloading up by about 1 lb/sq.ft.) )
I kept the OTL numbers for Oil and Coolant positions but changed the wording from "Shutters" to "Flaps" to reflect the re-design. I am sure the opening sized are incorrect considering the design but I, frankly, didn't even know where to start to get actual design numbers for the ATL P-38.
EDIT: I forgot to talk about how I calculated the Time to Climb. I broke the Rate of Climb down to 200' increments using MS Excel's LINEST function referencing the calculated ATL RoC (as described above) to get the formula constants (a,b,c,d) for a fourth degree polynomial (ax^3+bx^2+cx+d). I then figured the timelapse between each 200' and its predecessor (e.g. 200' - 400', 400' - 600', etc.) and used a simple sum to add them up for each altitude. Again, not perfectly accurate, but plenty close enough for our needs (I tested it using the OTL number and got with a few points for each altitude).
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I edited that last post, @Draconis and @tomo pauk , to explain how I got the Time to Climb.
Also, I am pretty sure I messed up on my measurement of the wing area. I will re-measure and correct the information.
Also, I am pretty sure I messed up on my measurement of the wing area. I will re-measure and correct the information.
I think you did too. I can't find my scaling ruler, since I moved, but by rule of thumb, unless you include a rear edge extension, it looks like the front extension is about 10 square feet per side, 5x2.