Ch.25 - At Years End (Dec 1943)
16 December 1943
Burbank, California, USA
“And the cold battery problems?”
Lt. Col. Kelsey had followed through with his plan to visit California to coordinate with Lockheed on their various fighter projects, chief among them the XP-80 and the P-38. He was now in a small board room at Lockheed headquarters in Burbank with Bob Gross, Hall Hibbard, Kelly Johnson, Milo Burcham, and a handful of USAAF and War Department liaisons to have an open discussion on Lockheed’s progress and the Army Air Forces’ changing needs.
Hibbard addressed his question, “We are moving the battery pack to mount it transversely in the gondola luggage compartment, here,” he slid the drawing across the table to Kelsey, “in the section between the flaps. We will have to increase the access panel size to accommodate and add some bracing for the weight but this arrangement will allow us to vent heat from the rear cockpit into the battery compartment and keep it from getting cold soaked. The slight forward shift in the center of gravity is corrected by moving the main oxygen tank in the left boom twenty-two inches aft and the second oxygen tank by six inches.”
“When can we expect these changes?”
“They are being added to the Nineteen-Forty-Three orders, so they will be on the line in a few weeks as part of Block-Twenty. Without the need to paint all the airplanes now, you should receive the first delivery of them no later than mid-January.”
“Any other changes with that production block?”
“Nothing major. We are adding a secondary switching system for the Emergency Fuel Booster pumps into the Throttle controls to automatically turn on the over-speed-boosters when throttles are advanced to Take-Off/Military-Power or better. This should get rid of any fuel pressure losses under high-power even if the pilot fails to turn on the Emergency system. Other than that, the Block-Twenties will be the same as the Block-Eighteens.”
Satisfied, Kelsey turned to Johnson, “What about the XP-80?”
Kelsey had been out at Muroc a few weeks prior to watch some ground and taxi tests of Lockheed’s new Jet and he was amazed at how quickly Johnson and his team had pulled the aircraft together. It was a sleek and simple design, nowhere near as radical as Johnson’s L-133 proposal from a couple years ago, but its simplicity is what made it so attractive. While he was there, though, the program ran into a problem when the engine sucked up some debris from the runway and blew itself apart. The last Kelsey heard was that they were trying to get a replacement from England.
“We’re still waiting for that damn engine.” Johnson was never one to mince words.
Hall explained, “De Havilland has only one other Halford engine so we need to wait for them to send it over. It is on its way and as long it doesn’t get held up in customs again we should have it before the end of the year.”
“Once the engine arrives,” Milo Burcham interjected, “I will be going back out to Muroc for flight tests.”
The men continued their conversation, covering the various aspects of the upcoming tests and addressing the statuses of their projects. Their test pilots were being kept quite busy with the various platforms. Burcham was focused on the XP-80 with Ralph Virden providing additional support. The recently returned Tony LeVier was taking over the P-38J testing and development program. Ralph Virden, Junior, like his father a Lockheed test pilot, was out in Nashville to help them run tests on their P-38 two-seater with Jimmie Mattern.
“The tests have been positive, so far. Jimmie says that the airplane is a little tail heavy but that they are ballasting it out to improve ground handling. They haven’t run full performance tests yet—they are waiting to get it properly leveled first.” Burcham knew his test pilots well and their capabilities.
“What about the Jay?”
Hibbard once more took over.
“The F29 engines are all set and installed in four aircraft. To get properly sized water tanks installed we had to shorten the Leading Edge fuel cells by two stations, reducing their capacity by about ten gallons each, but this allows for fifteen gallon water tanks for each engine without impeding maintenance access.”
“If the tanks are in the leading edge won’t there still be temperature issues? Why not move them behind the main spar?”
“By moving into the fuel space we have kept the water tanks behind the leading edge, same as the fuel cells. Between this and properly insulating the lines we should avoid condensation issues.” Hibbard continued, “We can’t move them behind the main spar because all of the J-Models have been fitted out with Culver’s Dive Recovery Flaps, so that space is used up by the machinery to operate the flaps. Farther outboard, between the main spar and the ailerons, we have added the new boosted aileron systems, so that space is used up too.”
One of the War Production Board liaisons spoke up for the first time, “are those necessary? It sounds like extra cost for not much gain.”
The Lockheed staff sat silently looking at the man as though he were a talking a duck from some cartoon. Kelsey decided he could best put the accountant’s fears to rest.
“Absolutely necessary. The enemy are moving ahead of us with some of their latest and the P-38 needs those systems to re-gain its edge. The last thing any of us want is for our young, American, boys to suffer because their airplane can’t do what they need it to.” He turned to Hibbard, “Any idea when production will sufficient to add these to the current line?”
Hall cleared his throat, “We are already beginning to stockpile the Dive Flap actuators as they trickle in. Since we aren’t sending field modification kits to the fronts, we expect we should have enough to overcome production short comings no later than February. At least, enough for one line. It may be another month or so after that before we can get both lines adding them—I can’t speak for when Bell can do it.”
“Sir, if I may?” Major Beeson, one of Kelsey’s subordinates in the Fighter Branch, got Kelsey’s attention, “if we want the flaps available sooner, what if we take the burden off the factory?”
“What are you proposing, Major?”
“Could we have Lockheed and their sub-contractors send the kits to the Modification Center in Texas for installation before sending the planes out to their groups, Sir?”
Kelsey considered it. “Not a bad idea, Major. Mister Hibbard, Mister Gross, if you have no objections I’d like to leave Major Beeson here with you to work out the details.”
“That’s fine.”
Hibbard continued with the P-38J update.
“The Hamilton-Standard and Curtiss three-blade jobs are ready and the Aeroproducts four-blade just arrived—we’re working on installing them right now. Curtiss has not finished their four-blade design yet but they have assured us it is on the way.”
“Have you looked into pressurization again?”
“We are starting to. We already have a preliminary design but it needs a lot of refinement. The system will be similar to the one we experimented with a few years back in the P-38A. Like that and XC-35, we would use bleed air from the turbos to provide pressure to the cockpit. It will use small diameter lines split after the inter-coolers and run up in the machinery space between the reserve tanks and the radiator outlets.”
Hibbard handed more drawings to Kelsey. These were rough schematics showing the installation and a pressure-system representational diagram illustrating the components of the system.
“The ducts then run aft to either side of the forward gear compartment and up to the lower portion of what is now the battery compartment. Here will be the cockpit pressure regulator. The regulator combines the two bleed lines and a supplementary oxygen line and releases directly into the cockpit. A small pressure bulkhead will be directly behind this with a pressure release valve which will vent through the bottom to one side of the ladder.
“A second pressure bulkhead will need to be installed in place of the existing firewall between the instrument panel and the nose compartment. The rest of the semi-monocoque will be its own pressure vessel—we just need to ensure all the seams are tight enough to hold the pressure.
“The Canopy is another problem area. We will have to replace the whole thing to ensure a tight seal. Kelly has lent us the drawings for the one-piece bubble from the XP-80, but it is far too small to fit on the P-38. We have tried a couple different solutions and we think we are close to finding one that will work but it will require entirely new molds. Sealing will be handled by using a modified version of the existing rolling-lock style sliding canopy but bolstered with semi-inflated rubber tube gaskets.
“In all we are expecting it to net at least 300 pounds of extra weight and, depending on how much pressure we take from the induction system, will also reduce the Critical Altitude by a few thousand feet. Of course, those are just estimates based on the initial design.”
Once more the War Department questioned the need for the extra cost and complexity of the system. The mounting successes of the 8th Air Force in Europe ever since the P-38s started to provide round-trip escort proved to everyone’s satisfaction that escorts are needed and with the ever increasing ranges and altitudes at which operations were taking place the only way future bombers can be protected is with fighters whose pilots are comfortable and fully conscious for the entire trip.
With their cases made, Lockheed received authorization to move forward with installing the new pressurization system on a test aircraft and to develop the new canopy.
“Any other changes to the Jay?”
“A few. We are already making some additional changes to the planes getting the four blade props and—if they work—we’ll be going back and doing the same for the other two before we send them your way.”
“What kind of changes?”
====================================
28 December 1943
Lockheed Air Terminal
Burbank, California, USA
Ralph Virden was on holiday for the week, so it was left to Tony LeVier to take the latest variant of the P-38J up for a test. The plane was already prepared, fueled, and had its nose filled with ballast in place of the guns which will eventually fill it out. It sat it the P-38’s customary semi-reclined stance with its new larger propeller spinners pointing to their target in the sky. These new spinners were interrupted now not with three but with four broad bladed propeller blades.
Tony was given the fifth pre-production J-Model known internally to Lockheed as Model 722-120-7, production serial number 722-1005. This particular airplane was recently fitted with new Aeroproducts Unimatic four-blade constant speed high-activity propellers. They only increased the disc area by a few percent but the increased swept area and geometry of the blades promised to capture the power of the new F29 water-injected engines.
Like all new P-38s coming out of the factory, this one was largely unpainted. Only the blue roundel emblazoned with the white star and flanked with the blue-outlined white bars of the AAF broke the sheen of the lightly polished “natural aluminum” of the booms. The tail was marked in simple black stencil with the Air Corp service number, “328252,” and the nose repeated the “252” identifier. The inboard sides of engine nacelles and the top of the nose were painted in Olive Drab “antiglare” panels.
After his walk around, egress to the cockpit was the same. This airplane still had the same three-piece sliding canopy as all of the Model 422 aircraft even though Tony was recently informed that a new two piece (front windscreen and one-piece “bubble”) was in the works. It was when he sat down that all of the changes became apparent.
The cockpit, for the first time in Tony’s experience, was a proper Fighter cockpit.
The installation of the hydraulically boosted ailerons removed the need to use two hands to roll the airplane at high speeds so Lockheed finally replaced the cumbersome off-set control column and steering-wheel-like yoke with a single, centrally mounted, stick. The hand grip was a simple modification of the right hand grip from the late model H airplanes, being ergonomically designed with a thumb-rest to the left and canted slight forward on its bend stick post.
The front of the grip had a red safety cover which the pilot could flip up to access the combined gun and cannon trigger behind it. The trigger safety doubled as the master Armament switch so that when it is flipped up it turns on the master gun circuits—replacing the old Armament switch which was on the old control column. At the top of the stick was a round red button which releases the external stores from the main hard points when they are properly armed. This switch also changes the operation of the trigger by switching the circuit to release whatever ordnance is fitted to the new outer-wing hard points—intended primarily for the new 5-inch Forward Firing Aerial Rockets but they can also be set up with shackles for small 100 pound or 250 pound bombs.
To make room for the stick in the center of the cockpit, the oxygen regulator and gauge were moved to the right of the cockpit, similar to where it was in other single-seat fighters—right where Tony was used to seeing the flap lever.
The flap lever was now mounted on the side of the Engine Control module, where the elevator trim tab was on the P-38F and G models. This arrangement would allow the pilot to manage all of the essential flight controls with his left hand while keeping his right hand on the stick.
The Engine Control module was the other big change in this particular aircraft—it was the first installation of the new Unit Engine Control jointly developed by Allison and Lockheed. While its use of simple spring-pins to lock the controls together was similar to the system in the P-47 its actual function was far more advanced and allowed for a non-linear interlinking of the Throttle, Speed, and Mixture controls.
The system, which Tony had helped refine with his feedback from pilots in England, used an ingenious series of stepped gears, bell-cranks, and pushrods, to act as a mechanical computer to proportionally adjust propeller speed and mixture automatically when the main throttle levers are moved. It can also be independently disengaged for each side so that the engines can still be set fully manually as always.
When the pins are released from their unlocked (un-coupled) position they force the main interlink gear to lock on to the throttle lever extensions in the unit box. As the throttles are advanced past the approximate position for 31 inHG manifold pressure it then engages the first engine speed cog which begins to advance the propeller levers at about 114 engine R.P.M per inch of M.P. advancement up to 2000 R.P.M. at 34.5 inHg M.P. when it tightens the ratio to just under 98 R.P.M per inch. This continues until Maximum Cruise engine settings are reached at about 2300 R.P.M. and 37.7 inHg M.P. when the crank engages a push rod which moves the mixture levers forward from AUTO LEAN into AUTO RICH, before continuing with a proportional advancement of about 51 R.P.M. per inch. Once the throttle is in the 54 inHg position and the engine speed lever is in the 3000 R.P.M. position a gap in the gear prevents the RPMs from moving any farther. This gap lasts until the throttles move past 60 inHg M.P. when it re-engages the engine speed control at 12.5 R.P.M per inch M.P. and, if the Water Injection switch on the side of the unit is flipped, ON, engages the Water Injection system. This it keeps all the way to the stop at 3200 R.P.M. and 76 inHg M.P. To prevent over-speeding the engine even if the throttles are pushed beyond their stops, the interlink is smooth beyond 3200 R.P.M.
One interesting feature touted by the engineers, which Tony was planning on trying out today, was that at any of set step-changes the system can engage the interlock spring pins. So, if the engine was under manual control at 2200 R.P.M. and only 30 inches of Manifold Pressure, the pilot can re-engage the automatic system by releasing the spring-pin, moving the R.P.M. to one of the set positions—such as 2300 R.P.M.—then push the throttle up as normal. When the throttle reaches the correct position to correspond to the set engine speed the interlock will automatically re-connect and the entire system acts a unit again whether the throttles are advanced or retarded. This should allow the system to automatically engage when the pilot first sets the engines for take-off.
With the interlock engaged in the LOCK position, Tony reached for the throttle handles just to get a feel for the resistance the new system would impart on the lever movement. The throttle handles themselves were no longer the simple red Bakelite balls but now the left was a stunted cylinder shape, angled up slightly to the plane of movement, and the right was a similar grip extending on the same line. Where the two grips came together a stepped notch cut from the top left of the right handle and a similar one on the lower right of the left handle allowed them to entirely overlap, simplifying the ergonomics of moving both throttles together. On the front of the right throttle handle was now the microphone button for the radio, pressed with either of the left hand’s first two fingers, and on the end of the handle was another button—pressed with the thumb—which activates the new Dive Recovery Flaps. In combat, the pilot can now keep his left hand on the throttles and the right on the stick.
Tony pushed the throttle levers forward, feeling the changes in gearing. The throttle movement was a little heavier now but no worse than if he had turned up the resistance on the lever. All of the interlinks now ensure that the levers will not be able to easily change position and shake loose, so the old and customary lever resistance adjuster is now absent from the unit. Where he expected, the resistance increased slightly as the radio stepped down. Again, at where he suspected 38 inHg and 2300 RPM would be, resistance momentary increased as a slight movement in the throttle forced the mixture control lever to move forward into AUTO RICH, after which it again lightened up slightly.
He continued this all the way forward to the stops, noting how the changes is resistance will give the pilot tactile feedback of where the engines are in their power range without having to closely monitor the instruments. Another possible advantage in combat.
Tony pulled out the pre-flight checklist, hand written by Ralph Virden for the flight. Tony never used these before becoming a Lockheed test pilot and they still made him feel more than a little patronized but after some pilots had missed steps a couple times Milo Burcham made all of his pilots use the lists.
(1) Battery switch OFF if battery cart is used. ON if cart is not used. (No cart, today, so Tony switched on the battery).
(2) Turn the manual tank selector valves to RESERVE.
(3) Fuel Selector Override switches OFF (down).
(4) Oxygen pressure 400 to 450 lb/sq in. (Tony saw #252 registered about 410 psi).
(5) Unit Engine Control interlock spring-pins UNLOCKED. (This was the new one, Tony slid the two pins over and back to secure them into the UNLOCKED position).
(6) Throttles 1/10 OPEN (3/4 inch).
(7) Propeller control INC RPM. (Full Forward).
(8) (This airplane does not use propeller control switches, the propellers will always operate in AUTO CONST. SPEED).(9) (This airplane does not have feathering switches—see below).
(10) Mixture IDLE CUTOFF.
(11) Oil cooler flap switches AUTOMATIC.
(12) Coolant radiator flap switches AUTOMATIC.
(13) Intercooler exit shutter switches AUTOMATIC.
(14) Intercooler inlet shutter switches AUTOMATIC.
(15) Generator switches ON.
(16) Inverter switch ON
(17) Armament safety switch CLOSED (irrelevant since there were no guns installed, but Tony checked it any way).
(18) Fuel quantity adequate. Check the fuel level in outer wing tanks by pressing the low level test button on the auxiliary fuel control switch box.
(19) Carburetor air filters AS REQUIRED. (It was a dusty day in the valley, so Tony moved the lever to open the filter doors).
(20) Clock and altimeter set.
With the pre-flight checks complete, Tony signaled the ground crew to turn over the propellers then flipped up both Priming/Oil Dilution switches to the ON position. With that he tested his booster pumps and checked all of his fuel levels. After confirming his pressures were good with the boosters in both NORMAL and EMERGENCY, he flipped the speed control back to NORMAL. The new Unit Engine Control module was already fitted with the automatic booster speed EMERGENCY override so, if all went well, he would not need to worry about manually switching back to EMERGENCY for Take-Off or his high power tests.
Tony flipped the master ignition switch forward to ON then turned the left hand ignition switch to BOTH magnetos. He held the left hand starter switch to ENER and listened for the inertial starter to get up to speed then pressed the switch forward to START. The new Allison F29L engine sputtered and fired. Tony pushed the mixture up to AUTO RICH and the engine roared to life.
The broad blades turned smoothly with only the quietest slap through the air as they came up to speed, nowhere near the sound of the long bladed Hamilton-Standard he flew in the original P-38J model test bed the past summer. The new propeller was subtly, but perceptibly, slower than Tony was used to—enough that he had to glance down to confirm the engine was running at a good idle around 1400 RPM. Once his oil pressures were stable and the engine running steady he repeated the start process for the right side.
Keying the new microphone button on the throttle handle, he tested his radio with a short check to the tower, “Burbank Tower, Lightning Two-Five-Two. Radio check.”
“Lightning Two-Five-Two, Tower, Receiving you Five-by-Five.”
With his radio check complete he continued with the other systems tests Ralph listed out in his checklist.
a. Extend and retract the flaps to check the operation of the hydraulic system. When both engines are operating at 1400 RPM, fifteen to twenty seconds in the normal extension time; twenty-five seconds is the normal extension time if only one engine is operating at 1400 RPM.
b. Check for normal fuel pressure 16 to 18 lb/sq in. with fuel booster pump speed control switches in NORMAL. Check for idling pressure of 9 lb/sq in.
c. Increase RPM to 2300.
(1) Synchronize the RH (right-hand) propeller to match the left using propeller lever Vernier knob.
(2) Check propeller control levers DEC RPM then INC RPM (full forward).
(3) Check magnetos. Maximum normal drop, 100 RPM after shifting from BOTH to either LEFT or RIGHT magneto. Engine must run smoothly on either magneto.
(4) With the generator switches ON, check the voltmeter for approximately 28 volts and the anmeters for charge.
(5) Check operation of the turbo-superchargers by opening the throttles individually to take-off power.
The propeller tests were of particular interest. The Unimatic created for the P-38 was a first for the Aeroproducts Propeller Company (Tony and the others had started simplifying the name to just “Aeroprop.”); it was their first fully feathering system. To get the propeller to feather the pilot pulls the propeller speed control lever all the way to DEC RPM and moves it through a detent which engages a step in the control cable. In the propeller hub, when the cable is moved through its step, all of the oil is bled from one side of the hydraulic piston which allows the pressure on the other side to force the propeller past its normal 63° pitch stop and all the way to 89°. Unlike the Hamilton-Standard “Hydromatic” system, which uses oil pressure from the engine, since the Aeroprop “Unimatic” has its own hydraulic system the propeller can be feathered even with a complete loss of engine oil pressure and unlike the Electric propellers, they will still be able to operate even in the event of electrical failure. They have the best of both worlds.
One idea Tony had heard discussed was being able to make the Aeroprop and Curitss propellers modular, regardless of which system was originally installed in the airplane. His understanding was that in order to do so, all of the planes would be pre-wired for the Electric system and have the manual pitch control cables pre-run. Switching from the Aeroprop to the Curtiss, then, would require installing the propeller control circuit breakers, Propeller Selector Switches, and installing the new propeller hub assembly. Instead of having a separate procedure for feathering, the Electric propellers will include a switch to initiate full feathering when the speed controls are moved through the detent to FEATHER.
Once the engines were good and warmed up, Tony set off.
Taxiing was the same as it always was with all of pumping the brakes to maintain pressure causing the airplane to dip and rock as it moved. Once he was on the line and given clearance to take off, Tony lowed his flaps half way and checked his engine settings one last time to make certain they were ready to engage the Unit Engine Control. While standing on the brakes with mixtures in AUTO RICH, he advanced his RPMs to 3000, then slapped the two interlink spring-pins forward out of their UNLOCK position. They gave a loud clink as their springs pushed the interlinks against the throttle lever connections. He pulled the RPMs back a little to confirm the interlinks were not yet fully locked then pushed them back up to 3000.
Tony tightened the oxygen mask around his face then wrapped his left hand around both throttle handles. Their new angle, just under 30 degrees from the horizontal, was very natural and with the two perfectly overlapped they really felt link a single unit. He pushed them up, listening as the turbos started to whistle with their increased pressure. The broad propellers chewed the air, their thrust fighting against the brakes. The entire airplane fought to lurch forward, pulling at the tether Tony was holding on it. When his manifolds were showing about 54”Hg he felt a short vibration pass into his left hand as the interlink locked in place.
He let the airplane lose.
The P-38 launched down the runway, the new engines and propellers paying to heed to added weight in the airplane. Tony watched his Airspeed climb and before he knew it the airplane was ready to rotate. A slight back-pressure on the stick, a movement less pronounced than it ever was with the yoke, and the 252’s nose lifted clear followed immediately by the main gear as the powerful Unimatic propellers pulled the Lightning into the sky.
When he lifted the gear there was a nibble on the stick. He knew from his previous flights in aircraft with the aileron boosters that this was normal and expected as the gear actuators used most of the pressure from the hydraulic system. Once he heard the electrical hum of the hydraulics stop and the gear position indicator lights turned off there was another nibble on the stick and Tony knew he had fully boosted ailerons again.
Clear of the field and all the nearby obstacles, Tony turned East to climb over the mountains and go to the empty desert beyond San Bernardino. He pulled the throttles back to 40” for the climb and was happy to see the engine speeds both come down to about 2400 RPM. The Unit Engine Control was working perfectly.
====================================
30 December 1943
Western Union Branch Office
Wayne County, Illinois, USA
XXXXXXX FAIRFIELD ILL DEC 30 1943 316PM
HEIDINGER HOMESTEAD=
:CAPT J.A.HEIDINGER
JIM SURPRISE AWAITING AT YOUR NEXT STATION=
FLOWERS MAY BE SENT TO MRS ALOYSIA LEVIER / 3964 MISSION AVE / ESCONDIDO CALIF=
HAPPY NEW YEAR=
:TONY LEVIER==
Burbank, California, USA
“And the cold battery problems?”
Lt. Col. Kelsey had followed through with his plan to visit California to coordinate with Lockheed on their various fighter projects, chief among them the XP-80 and the P-38. He was now in a small board room at Lockheed headquarters in Burbank with Bob Gross, Hall Hibbard, Kelly Johnson, Milo Burcham, and a handful of USAAF and War Department liaisons to have an open discussion on Lockheed’s progress and the Army Air Forces’ changing needs.
Hibbard addressed his question, “We are moving the battery pack to mount it transversely in the gondola luggage compartment, here,” he slid the drawing across the table to Kelsey, “in the section between the flaps. We will have to increase the access panel size to accommodate and add some bracing for the weight but this arrangement will allow us to vent heat from the rear cockpit into the battery compartment and keep it from getting cold soaked. The slight forward shift in the center of gravity is corrected by moving the main oxygen tank in the left boom twenty-two inches aft and the second oxygen tank by six inches.”
“When can we expect these changes?”
“They are being added to the Nineteen-Forty-Three orders, so they will be on the line in a few weeks as part of Block-Twenty. Without the need to paint all the airplanes now, you should receive the first delivery of them no later than mid-January.”
“Any other changes with that production block?”
“Nothing major. We are adding a secondary switching system for the Emergency Fuel Booster pumps into the Throttle controls to automatically turn on the over-speed-boosters when throttles are advanced to Take-Off/Military-Power or better. This should get rid of any fuel pressure losses under high-power even if the pilot fails to turn on the Emergency system. Other than that, the Block-Twenties will be the same as the Block-Eighteens.”
Satisfied, Kelsey turned to Johnson, “What about the XP-80?”
Kelsey had been out at Muroc a few weeks prior to watch some ground and taxi tests of Lockheed’s new Jet and he was amazed at how quickly Johnson and his team had pulled the aircraft together. It was a sleek and simple design, nowhere near as radical as Johnson’s L-133 proposal from a couple years ago, but its simplicity is what made it so attractive. While he was there, though, the program ran into a problem when the engine sucked up some debris from the runway and blew itself apart. The last Kelsey heard was that they were trying to get a replacement from England.
“We’re still waiting for that damn engine.” Johnson was never one to mince words.
Hall explained, “De Havilland has only one other Halford engine so we need to wait for them to send it over. It is on its way and as long it doesn’t get held up in customs again we should have it before the end of the year.”
“Once the engine arrives,” Milo Burcham interjected, “I will be going back out to Muroc for flight tests.”
The men continued their conversation, covering the various aspects of the upcoming tests and addressing the statuses of their projects. Their test pilots were being kept quite busy with the various platforms. Burcham was focused on the XP-80 with Ralph Virden providing additional support. The recently returned Tony LeVier was taking over the P-38J testing and development program. Ralph Virden, Junior, like his father a Lockheed test pilot, was out in Nashville to help them run tests on their P-38 two-seater with Jimmie Mattern.
“The tests have been positive, so far. Jimmie says that the airplane is a little tail heavy but that they are ballasting it out to improve ground handling. They haven’t run full performance tests yet—they are waiting to get it properly leveled first.” Burcham knew his test pilots well and their capabilities.
“What about the Jay?”
Hibbard once more took over.
“The F29 engines are all set and installed in four aircraft. To get properly sized water tanks installed we had to shorten the Leading Edge fuel cells by two stations, reducing their capacity by about ten gallons each, but this allows for fifteen gallon water tanks for each engine without impeding maintenance access.”
“If the tanks are in the leading edge won’t there still be temperature issues? Why not move them behind the main spar?”
“By moving into the fuel space we have kept the water tanks behind the leading edge, same as the fuel cells. Between this and properly insulating the lines we should avoid condensation issues.” Hibbard continued, “We can’t move them behind the main spar because all of the J-Models have been fitted out with Culver’s Dive Recovery Flaps, so that space is used up by the machinery to operate the flaps. Farther outboard, between the main spar and the ailerons, we have added the new boosted aileron systems, so that space is used up too.”
One of the War Production Board liaisons spoke up for the first time, “are those necessary? It sounds like extra cost for not much gain.”
The Lockheed staff sat silently looking at the man as though he were a talking a duck from some cartoon. Kelsey decided he could best put the accountant’s fears to rest.
“Absolutely necessary. The enemy are moving ahead of us with some of their latest and the P-38 needs those systems to re-gain its edge. The last thing any of us want is for our young, American, boys to suffer because their airplane can’t do what they need it to.” He turned to Hibbard, “Any idea when production will sufficient to add these to the current line?”
Hall cleared his throat, “We are already beginning to stockpile the Dive Flap actuators as they trickle in. Since we aren’t sending field modification kits to the fronts, we expect we should have enough to overcome production short comings no later than February. At least, enough for one line. It may be another month or so after that before we can get both lines adding them—I can’t speak for when Bell can do it.”
“Sir, if I may?” Major Beeson, one of Kelsey’s subordinates in the Fighter Branch, got Kelsey’s attention, “if we want the flaps available sooner, what if we take the burden off the factory?”
“What are you proposing, Major?”
“Could we have Lockheed and their sub-contractors send the kits to the Modification Center in Texas for installation before sending the planes out to their groups, Sir?”
Kelsey considered it. “Not a bad idea, Major. Mister Hibbard, Mister Gross, if you have no objections I’d like to leave Major Beeson here with you to work out the details.”
“That’s fine.”
Hibbard continued with the P-38J update.
“The Hamilton-Standard and Curtiss three-blade jobs are ready and the Aeroproducts four-blade just arrived—we’re working on installing them right now. Curtiss has not finished their four-blade design yet but they have assured us it is on the way.”
“Have you looked into pressurization again?”
“We are starting to. We already have a preliminary design but it needs a lot of refinement. The system will be similar to the one we experimented with a few years back in the P-38A. Like that and XC-35, we would use bleed air from the turbos to provide pressure to the cockpit. It will use small diameter lines split after the inter-coolers and run up in the machinery space between the reserve tanks and the radiator outlets.”
Hibbard handed more drawings to Kelsey. These were rough schematics showing the installation and a pressure-system representational diagram illustrating the components of the system.
“The ducts then run aft to either side of the forward gear compartment and up to the lower portion of what is now the battery compartment. Here will be the cockpit pressure regulator. The regulator combines the two bleed lines and a supplementary oxygen line and releases directly into the cockpit. A small pressure bulkhead will be directly behind this with a pressure release valve which will vent through the bottom to one side of the ladder.
“A second pressure bulkhead will need to be installed in place of the existing firewall between the instrument panel and the nose compartment. The rest of the semi-monocoque will be its own pressure vessel—we just need to ensure all the seams are tight enough to hold the pressure.
“The Canopy is another problem area. We will have to replace the whole thing to ensure a tight seal. Kelly has lent us the drawings for the one-piece bubble from the XP-80, but it is far too small to fit on the P-38. We have tried a couple different solutions and we think we are close to finding one that will work but it will require entirely new molds. Sealing will be handled by using a modified version of the existing rolling-lock style sliding canopy but bolstered with semi-inflated rubber tube gaskets.
“In all we are expecting it to net at least 300 pounds of extra weight and, depending on how much pressure we take from the induction system, will also reduce the Critical Altitude by a few thousand feet. Of course, those are just estimates based on the initial design.”
Once more the War Department questioned the need for the extra cost and complexity of the system. The mounting successes of the 8th Air Force in Europe ever since the P-38s started to provide round-trip escort proved to everyone’s satisfaction that escorts are needed and with the ever increasing ranges and altitudes at which operations were taking place the only way future bombers can be protected is with fighters whose pilots are comfortable and fully conscious for the entire trip.
With their cases made, Lockheed received authorization to move forward with installing the new pressurization system on a test aircraft and to develop the new canopy.
“Any other changes to the Jay?”
“A few. We are already making some additional changes to the planes getting the four blade props and—if they work—we’ll be going back and doing the same for the other two before we send them your way.”
“What kind of changes?”
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28 December 1943
Lockheed Air Terminal
Burbank, California, USA
Ralph Virden was on holiday for the week, so it was left to Tony LeVier to take the latest variant of the P-38J up for a test. The plane was already prepared, fueled, and had its nose filled with ballast in place of the guns which will eventually fill it out. It sat it the P-38’s customary semi-reclined stance with its new larger propeller spinners pointing to their target in the sky. These new spinners were interrupted now not with three but with four broad bladed propeller blades.
Tony was given the fifth pre-production J-Model known internally to Lockheed as Model 722-120-7, production serial number 722-1005. This particular airplane was recently fitted with new Aeroproducts Unimatic four-blade constant speed high-activity propellers. They only increased the disc area by a few percent but the increased swept area and geometry of the blades promised to capture the power of the new F29 water-injected engines.
Like all new P-38s coming out of the factory, this one was largely unpainted. Only the blue roundel emblazoned with the white star and flanked with the blue-outlined white bars of the AAF broke the sheen of the lightly polished “natural aluminum” of the booms. The tail was marked in simple black stencil with the Air Corp service number, “328252,” and the nose repeated the “252” identifier. The inboard sides of engine nacelles and the top of the nose were painted in Olive Drab “antiglare” panels.
After his walk around, egress to the cockpit was the same. This airplane still had the same three-piece sliding canopy as all of the Model 422 aircraft even though Tony was recently informed that a new two piece (front windscreen and one-piece “bubble”) was in the works. It was when he sat down that all of the changes became apparent.
The cockpit, for the first time in Tony’s experience, was a proper Fighter cockpit.
The installation of the hydraulically boosted ailerons removed the need to use two hands to roll the airplane at high speeds so Lockheed finally replaced the cumbersome off-set control column and steering-wheel-like yoke with a single, centrally mounted, stick. The hand grip was a simple modification of the right hand grip from the late model H airplanes, being ergonomically designed with a thumb-rest to the left and canted slight forward on its bend stick post.
The front of the grip had a red safety cover which the pilot could flip up to access the combined gun and cannon trigger behind it. The trigger safety doubled as the master Armament switch so that when it is flipped up it turns on the master gun circuits—replacing the old Armament switch which was on the old control column. At the top of the stick was a round red button which releases the external stores from the main hard points when they are properly armed. This switch also changes the operation of the trigger by switching the circuit to release whatever ordnance is fitted to the new outer-wing hard points—intended primarily for the new 5-inch Forward Firing Aerial Rockets but they can also be set up with shackles for small 100 pound or 250 pound bombs.
To make room for the stick in the center of the cockpit, the oxygen regulator and gauge were moved to the right of the cockpit, similar to where it was in other single-seat fighters—right where Tony was used to seeing the flap lever.
The flap lever was now mounted on the side of the Engine Control module, where the elevator trim tab was on the P-38F and G models. This arrangement would allow the pilot to manage all of the essential flight controls with his left hand while keeping his right hand on the stick.
The Engine Control module was the other big change in this particular aircraft—it was the first installation of the new Unit Engine Control jointly developed by Allison and Lockheed. While its use of simple spring-pins to lock the controls together was similar to the system in the P-47 its actual function was far more advanced and allowed for a non-linear interlinking of the Throttle, Speed, and Mixture controls.
The system, which Tony had helped refine with his feedback from pilots in England, used an ingenious series of stepped gears, bell-cranks, and pushrods, to act as a mechanical computer to proportionally adjust propeller speed and mixture automatically when the main throttle levers are moved. It can also be independently disengaged for each side so that the engines can still be set fully manually as always.
When the pins are released from their unlocked (un-coupled) position they force the main interlink gear to lock on to the throttle lever extensions in the unit box. As the throttles are advanced past the approximate position for 31 inHG manifold pressure it then engages the first engine speed cog which begins to advance the propeller levers at about 114 engine R.P.M per inch of M.P. advancement up to 2000 R.P.M. at 34.5 inHg M.P. when it tightens the ratio to just under 98 R.P.M per inch. This continues until Maximum Cruise engine settings are reached at about 2300 R.P.M. and 37.7 inHg M.P. when the crank engages a push rod which moves the mixture levers forward from AUTO LEAN into AUTO RICH, before continuing with a proportional advancement of about 51 R.P.M. per inch. Once the throttle is in the 54 inHg position and the engine speed lever is in the 3000 R.P.M. position a gap in the gear prevents the RPMs from moving any farther. This gap lasts until the throttles move past 60 inHg M.P. when it re-engages the engine speed control at 12.5 R.P.M per inch M.P. and, if the Water Injection switch on the side of the unit is flipped, ON, engages the Water Injection system. This it keeps all the way to the stop at 3200 R.P.M. and 76 inHg M.P. To prevent over-speeding the engine even if the throttles are pushed beyond their stops, the interlink is smooth beyond 3200 R.P.M.
One interesting feature touted by the engineers, which Tony was planning on trying out today, was that at any of set step-changes the system can engage the interlock spring pins. So, if the engine was under manual control at 2200 R.P.M. and only 30 inches of Manifold Pressure, the pilot can re-engage the automatic system by releasing the spring-pin, moving the R.P.M. to one of the set positions—such as 2300 R.P.M.—then push the throttle up as normal. When the throttle reaches the correct position to correspond to the set engine speed the interlock will automatically re-connect and the entire system acts a unit again whether the throttles are advanced or retarded. This should allow the system to automatically engage when the pilot first sets the engines for take-off.
With the interlock engaged in the LOCK position, Tony reached for the throttle handles just to get a feel for the resistance the new system would impart on the lever movement. The throttle handles themselves were no longer the simple red Bakelite balls but now the left was a stunted cylinder shape, angled up slightly to the plane of movement, and the right was a similar grip extending on the same line. Where the two grips came together a stepped notch cut from the top left of the right handle and a similar one on the lower right of the left handle allowed them to entirely overlap, simplifying the ergonomics of moving both throttles together. On the front of the right throttle handle was now the microphone button for the radio, pressed with either of the left hand’s first two fingers, and on the end of the handle was another button—pressed with the thumb—which activates the new Dive Recovery Flaps. In combat, the pilot can now keep his left hand on the throttles and the right on the stick.
Tony pushed the throttle levers forward, feeling the changes in gearing. The throttle movement was a little heavier now but no worse than if he had turned up the resistance on the lever. All of the interlinks now ensure that the levers will not be able to easily change position and shake loose, so the old and customary lever resistance adjuster is now absent from the unit. Where he expected, the resistance increased slightly as the radio stepped down. Again, at where he suspected 38 inHg and 2300 RPM would be, resistance momentary increased as a slight movement in the throttle forced the mixture control lever to move forward into AUTO RICH, after which it again lightened up slightly.
He continued this all the way forward to the stops, noting how the changes is resistance will give the pilot tactile feedback of where the engines are in their power range without having to closely monitor the instruments. Another possible advantage in combat.
Tony pulled out the pre-flight checklist, hand written by Ralph Virden for the flight. Tony never used these before becoming a Lockheed test pilot and they still made him feel more than a little patronized but after some pilots had missed steps a couple times Milo Burcham made all of his pilots use the lists.
(1) Battery switch OFF if battery cart is used. ON if cart is not used. (No cart, today, so Tony switched on the battery).
(2) Turn the manual tank selector valves to RESERVE.
(3) Fuel Selector Override switches OFF (down).
(4) Oxygen pressure 400 to 450 lb/sq in. (Tony saw #252 registered about 410 psi).
(5) Unit Engine Control interlock spring-pins UNLOCKED. (This was the new one, Tony slid the two pins over and back to secure them into the UNLOCKED position).
(6) Throttles 1/10 OPEN (3/4 inch).
(7) Propeller control INC RPM. (Full Forward).
(8) (This airplane does not use propeller control switches, the propellers will always operate in AUTO CONST. SPEED).(9) (This airplane does not have feathering switches—see below).
(10) Mixture IDLE CUTOFF.
(11) Oil cooler flap switches AUTOMATIC.
(12) Coolant radiator flap switches AUTOMATIC.
(13) Intercooler exit shutter switches AUTOMATIC.
(14) Intercooler inlet shutter switches AUTOMATIC.
(15) Generator switches ON.
(16) Inverter switch ON
(17) Armament safety switch CLOSED (irrelevant since there were no guns installed, but Tony checked it any way).
(18) Fuel quantity adequate. Check the fuel level in outer wing tanks by pressing the low level test button on the auxiliary fuel control switch box.
(19) Carburetor air filters AS REQUIRED. (It was a dusty day in the valley, so Tony moved the lever to open the filter doors).
(20) Clock and altimeter set.
With the pre-flight checks complete, Tony signaled the ground crew to turn over the propellers then flipped up both Priming/Oil Dilution switches to the ON position. With that he tested his booster pumps and checked all of his fuel levels. After confirming his pressures were good with the boosters in both NORMAL and EMERGENCY, he flipped the speed control back to NORMAL. The new Unit Engine Control module was already fitted with the automatic booster speed EMERGENCY override so, if all went well, he would not need to worry about manually switching back to EMERGENCY for Take-Off or his high power tests.
Tony flipped the master ignition switch forward to ON then turned the left hand ignition switch to BOTH magnetos. He held the left hand starter switch to ENER and listened for the inertial starter to get up to speed then pressed the switch forward to START. The new Allison F29L engine sputtered and fired. Tony pushed the mixture up to AUTO RICH and the engine roared to life.
The broad blades turned smoothly with only the quietest slap through the air as they came up to speed, nowhere near the sound of the long bladed Hamilton-Standard he flew in the original P-38J model test bed the past summer. The new propeller was subtly, but perceptibly, slower than Tony was used to—enough that he had to glance down to confirm the engine was running at a good idle around 1400 RPM. Once his oil pressures were stable and the engine running steady he repeated the start process for the right side.
Keying the new microphone button on the throttle handle, he tested his radio with a short check to the tower, “Burbank Tower, Lightning Two-Five-Two. Radio check.”
“Lightning Two-Five-Two, Tower, Receiving you Five-by-Five.”
With his radio check complete he continued with the other systems tests Ralph listed out in his checklist.
a. Extend and retract the flaps to check the operation of the hydraulic system. When both engines are operating at 1400 RPM, fifteen to twenty seconds in the normal extension time; twenty-five seconds is the normal extension time if only one engine is operating at 1400 RPM.
b. Check for normal fuel pressure 16 to 18 lb/sq in. with fuel booster pump speed control switches in NORMAL. Check for idling pressure of 9 lb/sq in.
c. Increase RPM to 2300.
(1) Synchronize the RH (right-hand) propeller to match the left using propeller lever Vernier knob.
(2) Check propeller control levers DEC RPM then INC RPM (full forward).
(3) Check magnetos. Maximum normal drop, 100 RPM after shifting from BOTH to either LEFT or RIGHT magneto. Engine must run smoothly on either magneto.
(4) With the generator switches ON, check the voltmeter for approximately 28 volts and the anmeters for charge.
(5) Check operation of the turbo-superchargers by opening the throttles individually to take-off power.
The propeller tests were of particular interest. The Unimatic created for the P-38 was a first for the Aeroproducts Propeller Company (Tony and the others had started simplifying the name to just “Aeroprop.”); it was their first fully feathering system. To get the propeller to feather the pilot pulls the propeller speed control lever all the way to DEC RPM and moves it through a detent which engages a step in the control cable. In the propeller hub, when the cable is moved through its step, all of the oil is bled from one side of the hydraulic piston which allows the pressure on the other side to force the propeller past its normal 63° pitch stop and all the way to 89°. Unlike the Hamilton-Standard “Hydromatic” system, which uses oil pressure from the engine, since the Aeroprop “Unimatic” has its own hydraulic system the propeller can be feathered even with a complete loss of engine oil pressure and unlike the Electric propellers, they will still be able to operate even in the event of electrical failure. They have the best of both worlds.
One idea Tony had heard discussed was being able to make the Aeroprop and Curitss propellers modular, regardless of which system was originally installed in the airplane. His understanding was that in order to do so, all of the planes would be pre-wired for the Electric system and have the manual pitch control cables pre-run. Switching from the Aeroprop to the Curtiss, then, would require installing the propeller control circuit breakers, Propeller Selector Switches, and installing the new propeller hub assembly. Instead of having a separate procedure for feathering, the Electric propellers will include a switch to initiate full feathering when the speed controls are moved through the detent to FEATHER.
Once the engines were good and warmed up, Tony set off.
Taxiing was the same as it always was with all of pumping the brakes to maintain pressure causing the airplane to dip and rock as it moved. Once he was on the line and given clearance to take off, Tony lowed his flaps half way and checked his engine settings one last time to make certain they were ready to engage the Unit Engine Control. While standing on the brakes with mixtures in AUTO RICH, he advanced his RPMs to 3000, then slapped the two interlink spring-pins forward out of their UNLOCK position. They gave a loud clink as their springs pushed the interlinks against the throttle lever connections. He pulled the RPMs back a little to confirm the interlinks were not yet fully locked then pushed them back up to 3000.
Tony tightened the oxygen mask around his face then wrapped his left hand around both throttle handles. Their new angle, just under 30 degrees from the horizontal, was very natural and with the two perfectly overlapped they really felt link a single unit. He pushed them up, listening as the turbos started to whistle with their increased pressure. The broad propellers chewed the air, their thrust fighting against the brakes. The entire airplane fought to lurch forward, pulling at the tether Tony was holding on it. When his manifolds were showing about 54”Hg he felt a short vibration pass into his left hand as the interlink locked in place.
He let the airplane lose.
The P-38 launched down the runway, the new engines and propellers paying to heed to added weight in the airplane. Tony watched his Airspeed climb and before he knew it the airplane was ready to rotate. A slight back-pressure on the stick, a movement less pronounced than it ever was with the yoke, and the 252’s nose lifted clear followed immediately by the main gear as the powerful Unimatic propellers pulled the Lightning into the sky.
When he lifted the gear there was a nibble on the stick. He knew from his previous flights in aircraft with the aileron boosters that this was normal and expected as the gear actuators used most of the pressure from the hydraulic system. Once he heard the electrical hum of the hydraulics stop and the gear position indicator lights turned off there was another nibble on the stick and Tony knew he had fully boosted ailerons again.
Clear of the field and all the nearby obstacles, Tony turned East to climb over the mountains and go to the empty desert beyond San Bernardino. He pulled the throttles back to 40” for the climb and was happy to see the engine speeds both come down to about 2400 RPM. The Unit Engine Control was working perfectly.
====================================
30 December 1943
Western Union Branch Office
Wayne County, Illinois, USA
XXXXXXX FAIRFIELD ILL DEC 30 1943 316PM
HEIDINGER HOMESTEAD=
:CAPT J.A.HEIDINGER
JIM SURPRISE AWAITING AT YOUR NEXT STATION=
FLOWERS MAY BE SENT TO MRS ALOYSIA LEVIER / 3964 MISSION AVE / ESCONDIDO CALIF=
HAPPY NEW YEAR=
:TONY LEVIER==
Another detailed and interesting chapter EverKing.
I would liked to have seen just a little more info on Tony LeVier's test flight. Like if he really wrings out that ATL P-38J to see how fast a climb rate and level airspeed it can do. Doing full aileron rolls at high speed to check out the aileron boost. Having Tony Levier mentally comparing these results to the P-38H. Maybe followed by a screaming power dive from 30,000 feet to test the dive recovery flaps. That would be a lot of fun.
Looking forward to more.
I would liked to have seen just a little more info on Tony LeVier's test flight. Like if he really wrings out that ATL P-38J to see how fast a climb rate and level airspeed it can do. Doing full aileron rolls at high speed to check out the aileron boost. Having Tony Levier mentally comparing these results to the P-38H. Maybe followed by a screaming power dive from 30,000 feet to test the dive recovery flaps. That would be a lot of fun.
Looking forward to more.
This was the first flight so he wasn't going to test the limits, it is really just a systems check. If you notice, I have been avoiding detailed flights in the J so far...I want there to be a real impact when we finally get to see it stretch its legs.
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Hooray! The P-38 finally gets what it should have had from the beginning. A joystick. One version of why it was equipped with a wheel was the original request from the Army Air Corp called for an interceptor, not a pursuit plane as funding for pursuit planes was already allocated. And putting in a control wheel was a way of "proving" it was not really a pursuit plane in disguise. Not sure of the validity of this as the P-39 was built for the same request.
That Unit Engine Control device is remarkably sophisticated. I was expecting some simple flange or pin on the throttle that would simply grab the mixture lever and the propeller control lever so when the pilot shoved the throttles full forward the other engine controls would move forward right to the stops simultaneously so the pilot would not inadvertently blow up the engines.
I think you can still do that with the UEC right? And be able to quickly move to other preset settings as well if I understand this device. If the throttles was already forward and the RPM and mixture controls back in the Lindbergh fuel saving setting my described simple grabber wouldn't work as the throttle levers would already be forward of the mixture and RPM levers. But that would not be any problem for the UEC as I understand it.
That Unit Engine Control device is remarkably sophisticated. I was expecting some simple flange or pin on the throttle that would simply grab the mixture lever and the propeller control lever so when the pilot shoved the throttles full forward the other engine controls would move forward right to the stops simultaneously so the pilot would not inadvertently blow up the engines.
I think you can still do that with the UEC right? And be able to quickly move to other preset settings as well if I understand this device. If the throttles was already forward and the RPM and mixture controls back in the Lindbergh fuel saving setting my described simple grabber wouldn't work as the throttle levers would already be forward of the mixture and RPM levers. But that would not be any problem for the UEC as I understand it.
Well done again. A continuing insight into design & construction, & production, details. I had no idea, & it is (to borrow a catchword) fascinating.
Case in point.
So there were beancounter REMFs even then?
So much for the greatest generation.An elegant solution, but is it period correct? It has a very Vietnam-era feel too it, a level of sophistication I wouldn't expect in WW2. (Maybe I'm quibbling.)
This, OTOH, is exactly what I'd expect in WW2: something not far short of Rube Goldberg, because that's the best the tech could do.
Again, I wonder if that's a bit beyond the state of the art: it reminds me of a late '60s or early '70s jetliner, not a '40s bomber or airliner.
I was wondering if that was deliberate, or an artifact of the system that coincidentally works that way. (That said, wouldn't engine note offer a hint? Or is that too subtle, given the rev range?)
Good on Burcham.
It's the things you do all the time, only to leave out crucial steps in a crisis, that will kill you. That's why there are checklists. (That's also why you have to memorize the procedure for something you might do once in your flying career: exactly because you might only do it once, so you better know how...)Also good on you for putting the checklist in.
EverKing said:
And that is the mark of a real pro.
What do you think about using half flap setting for takeoff in a P-38? Unless very heavily loaded with external loads I would've thought pilots would have preferred no flaps for takeoff to get the slightly quicker acceleration they would get without the added lift/drags of flaps. The idea being to get above the minimum single engine control speed ASAP.
Couldn't agree more about the checklist. Keeping to it is the mark of a professional. Especially as planes get more complicated. The only exception being if there is a scramble and in that case the stand-by planes are being kept ready and their engines are already warmed up by the crew chiefs.
Couldn't agree more about the checklist. Keeping to it is the mark of a professional. Especially as planes get more complicated. The only exception being if there is a scramble and in that case the stand-by planes are being kept ready and their engines are already warmed up by the crew chiefs.
The tech was all there and this seemed the simplest way to make the switch gear compact enough for the stick. Many airplanes used the flip up safety cover in other systems (bomb release, armament master switch, etc.) I just made it dual function. Same with the thumb switch. I wanted to avoid an overly anachronistic selector switch and this seemed to be way to get it.
Not so. The angled throttle handle was pretty common in single engine fighters. If Lockheed's goal was to make it feel as much like a single engine fighter as reasonable they needed to combine the two throttles in such a way as to mimic this. The overlapping method was adapted from and directly inspired by the engine controls in a B-17...which Lockheed has been building for several years in their Vega division.
An artifact. Engine tone is good but the added benefit of the tactile changes will allow the pilot to hit those specific points with greater ease.
I have even more and will share them later in the TL if there is interest. I needed to re-write many of the Pilot Operation Instructions as a way to help figure out how to make the changes work and how the pilots would experience them (such as fuel management and now prop/speed managment).
He didn't need it but he was in a mood to get off the ground in as little space as possible.
For a single seat fighter adding oxygen directly to the cockpit pressurization system may not be the optimal approach. Because of the inevitable leakage much of the supplementary O2 added to the cockpit air will be lost. Unlike the flight deck of a bomber it's much simpler to supply the O2 directly to the lone pilot.
The pilot can still receive all the O2 he needs through the face mask and still benefit from the pressurizing of the cockpit. The cockpit only needs to be kept pressurized to around 15 inches, about 18,000 feet ASL equivalent to protect the pilot from the deleterious physiological effects of low atmospheric air pressure at higher altitudes. Especially on those long duration flights.
The bleed air system is good but it can be simplified by not adding supplementary oxygen to the cockpit through the pressure regulator. It would also protect the pilot in the event combat damage or structural failure causes an unexpected and rapid depressurization of the cockpit as he would always be using the oxygen mask above 10,000 feet.
The switch cover is something I've seen on the panel, but I don't think I'd have had the nerve to put it on the stick; it would've felt wrong. Kudos for doing it.
The single lever, I'm embarrassed to say, I didn't make the connection.I'd be interested, but I'm nuts for fine details.
(I'm trying hard not to complain you haven't mentioned the font of the gauge lettering. And how tall are those side numbers, enyhow?)I'm less sure it's essential for us to appreciate the story, tho it might be for you in getting a handle on how much has changed, & how to deal with it narratively: it's the kind of thing you may need to absorb, but not pass on. It's a bit like Dave Gibbons' drawing of the central intersection for Watchmen: he did it to orient himself to everything, but found, once he'd done it, he never needed to look at it again.
That's a good thing, IMO. It addresses my first concern, namely, the risk of anoxia, & the bends, in the event of loss of pressurization: breathing 100% O2 at all times means no nitrogen bubbles in the blood.
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The switch cover is something I've seen on the panel, but I don't think I'd have had the nerve to put it on the stick; it would've felt wrong. Kudos for doing it.
That's a good thing, IMO. It addresses my first concern, namely, the risk of anoxia, & the bends, in the event of loss of pressurization: breathing 100% O2 at all times means no nitrogen bubbles in the blood.
The pilots should be selecting full oxygen above 20,000 feet in an unpressurized airplane. In the pressurized plane they should still be doing the same. If they're at 30,000 feet and there is a sudden loss of cockpit pressure the full O2 feed will keep them conscious.
Good point about the bends. A sudden and rapid drop from the pressurized 15 inches hg to the 7 inches at 30,000 could bring on the bends if the pilot hasn't been breathing 100% O2 for a while after climbing up from less than 20,000 to 30,000 feet. They could also be flying a lot higher than 30,000. Up to and past 40,000 feet to really take advantage of the pressurization.
I wonder how long it would take to remove the nitrogen from the blood and tissues by breathing pure oxygen? Many war time pilots also discovered breathing pure O2 was also a good way to remove alcohol from the blood and cure hangovers before flying.
The idea behind adding a little O2 to the pressure system was more about supplementing pressure than for the pilot's breathing. The pilot would still be expected and required to breathe pure O2 from the mask. My hope was that by adding a little more air to the system will allow a couple more inches of pressure without bleeding as much air from the engines. They may decide to drop the system to remove the complexity and just accept that a higher cabin alt is adequate. Or, they may have the bleed air increase cabin pressure by, say a max of 10 inHg and add another 1-2 inHg by adding O2 from the tanks.
[EDIT: these numbers are just examples. If the bleed system could accommodate up to 10 inHG cabin alt increase then we're looking at keeping a cabin alt of 12200 at 30000 ft pressure alt. which is probably a little optimistic. More likely, the increase would be in the 7-8 inHg range for a Cabin Alt of just over 16,000 ft. at 30,000 ft. If that is the case, it would be set up to maintain a cabin alt of probably around 12,500 ft up to the ciritical altitude of about 24,000 feet after which cabin alt would increase proportionally with pressure alt. Tagging @Draconis because you'd already "liked" the post before the edit]
[EDIT: these numbers are just examples. If the bleed system could accommodate up to 10 inHG cabin alt increase then we're looking at keeping a cabin alt of 12200 at 30000 ft pressure alt. which is probably a little optimistic. More likely, the increase would be in the 7-8 inHg range for a Cabin Alt of just over 16,000 ft. at 30,000 ft. If that is the case, it would be set up to maintain a cabin alt of probably around 12,500 ft up to the ciritical altitude of about 24,000 feet after which cabin alt would increase proportionally with pressure alt. Tagging @Draconis because you'd already "liked" the post before the edit]
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I couldn't agree more. One of things about this that I have enjoyed the most is that all of us have brought our own expertise to the thread. Everyone's input has been a huge help to me as I've tried to improve the airplane and apply all the disparate knowledge as best I can.
I sure hope you all stick around with me while I work to continue the ATL P-38 story and eventually bring it to a close. We are about half way there. I think I may branch out as well, either later in this thread or as a "spin-off" thread (or threads), with the dedicated attack version of the P-47 and possibly with other aircraft affected by the continued development of the P-38 described in this thread.
Those numbers look pretty good. It's sufficient pressurization for pretty much any practical altitude the ATL P-38 is going to be flying at. After all the pilots of these planes are fit young men. They can handle a reasonable amount of high altitude better than the average modern airliner passenger.
IIRC, the Apollo flights all began prebreathing 100% O2 3h before launch, but that was with the spacecraft only pressurized to 3.7psi. (As I think about it now, that's absurdly low
--but that's the number Mike Collins mentions.)Is that a *hint hint* for a future TL from me?
Please finish this one first. Future hints/suggestions/demands to follow at a later date.
There is enough lack of focus as it is. I'm almost ready to suggest you attend a seminar with Yoda as it is.
Do, or don't do. There is no try.