Monday, February 1, 2016

January XP-82 Twin Mustang Restoration Project Update

2016 is going to be a banner year
for our XP-82

Fuel Systems
The major job this past month has been installing the wing and center section fuel tanks, boost pumps, liquidometers and sump drains.  The installation of the two center section 95-gallon tanks was completed around the first week in January. Three of the four outboard tanks are now installed less their pumps and liquidometers. All of these will be completed when the fourth tank is finished around the first week of February.

Left-hand and right-hand installed boost pumps less safety wire

Inboard Gear Doors
The job that I had been planning for years was to manufacture the two exceptionally complex-formed inboard gear doors. We recovered two extremely damaged inboard doors from the Alaska wreck site. Neither one had any usable parts, but parts of both gave us highly valuable information. Between these two crashed door remains and the very detailed NAA plans that we have, two team members were able to complete both door frames in a short amount of time. The pattern of the press die for the inside skins is being designed.

One of our machine shops supplied us with our four needed gear door hinge points. 

Upper & Lower Engine Cowlings
Our machine shop finished all of the 4130-steel left-hand and right-hand upper cowling adjustable-Dzus-rail-attach points. These are the attachment fittings that join the two top cowls together down the centerline of the top of each Merlin engine. 

With the lower cowling ribs being finished over the past month, the English wheeling of the six (three each engine) lower cowls has been started. Within a short amount to time, the team had the first forward lower wheeled cowl completed. The wheeling of the five remaining cowls should go smoothly. The two filtered-air screen ducts still need to be fitted in the sides of each forward cowl.

It would have been nice if these cowls were the same as a “D” model Mustang so that they could have been purchased from the current P-51 parts builders, but no such luck.

Armament / Replica Machine Guns
We received our six machine guns from the machine shop. The duplication and detail of all the parts copied from a non-fireable real .50 caliber gun are superb. All we had to do was paint and assemble each gun, and now all six are being installed in the center section gun bays.

I was also able to locate through a machine gun dealer/friend of mine, enough original WWII  .50 caliber fired shell casings with the correct date code “44” stamped on the back of each shell for authenticity. 

Rollout Time Frame
We are planning for the first roll out of our XP-82 to see the light of day sometime early this summer. The main task that has to be accomplished prior to that rollout is the completion and installation of the tail wheel retract mechanisms/tail wheel assemblies. 

At that time we will have Nixon’s Vintage V12s (company that overhauled our two engines) come from California to start both engines and final test all firewall forward systems (fuel, oil, vacuum, hydraulic, propeller, etc., etc.).

Final Major Tasks to Complete
The five major tasks to complete are as follows:  the pressing of the one FWF dishpan and the two inboard gear door waffle skins, fitting the two outboard gear doors, and machining and installing the two brake calipers. The last item is the pressing and assembly of the air induction trunk forward lip/carburetor air control mechanism (two) located under the prop spinners.

The Kat
Do you want the length or the width?”


Saturday, January 2, 2016

December XP-82 Twin Mustang Restoration Project Update

Another year has gone by so quickly.

But looking back at all the pictures that were taken in 

December 2014, a tremendous amount has been accomplished.

Center Section Leading Edge Assembly
This leading edge sub-assembly has been completed for some time now, and two team members spent a week fitting it to the leading edge spar. This was a complex job as it had to fit around and in between all of the forward gear door up-lock mechanisms mounted on the forward spar. Also, the six gun ports had to be properly positioned in the leading edge skin to align with the .50 cal. gun barrel blast (cooling) tubes. The leading edge assembly must remain off to perform the preliminary adjustments of the gear door up-locks during the gear retraction tests. 

Leading edge being fit 
(notice the prop spinners on left-hand side of the center section)

Belly Scoops/Radiators/Coolant Header Tanks
The final two Dzus/nut plate panels that close out at and aft of the bottom of each radiator have now been completed. All four feed and return 2” coolant lines are now completed, along with the 1.25” intercooler lines.  

Both pressure relief valves, one each mounted on each coolant header tank, are now overhauled and installed.

Pressure relief valves for the coolant header tanks

Coolant header tank with one pressure relief valve installed

Special XP-82/P-51 Coolant Water Necks
These coolant water necks are peculiar to only the Merlin-powered XP-82 and P-51H engines. They were not included with the overhauled engines as they are considered part of the cooling system. With much searching Nixon Vintage V-12s (the facility in Tehachapi CA, that overhauled our two engines) came up with two pair of them. Thanks. They are now permanently installed on both engines.

Main water inlet to engine water pump installed

Water necks installed on the Merlin engine

Firewall Forward Jobs
The majority of the month of December has been taken up completing all of the miscellaneous must-be-completed FWF jobs. All of the feed and return vacuum lines from the vacuum pumps to each firewall and air/oil separators have now been completed. 

On the left-hand firewall, there is a pressure-controlling valve that controls the vacuum pump discharge pressure airflow through pilot-selected lines out to drop tanks mounted on both wings. This vacuum pump discharge pressure is used to pressurize each drop tank to push and transfer the fuel without the help of a fuel pump back through return lines to the 95-gallon inboard fuel tank, a unique design.  We had three of these valves that had been under water for countless years and fortunately, among all three valves, enough airworthy parts were recovered to restore one good valve. 

Two vacuum air/oil separators, two ignition starting boosters in their mounting boxes, two pre-oil solenoids and check valves, two tach generators and the two electric/mechanical carburetor air control mechanisms have now been permanently installed.

Air/oil vacuum separator

Starting ignition vibrator

Pre-oil solenoid

Carburetor air control mechanisms

Temperature Probes (Oil and Coolant), Chip Detectors & Drain Ports
On a number of the coolant and oil lines, temperature resistance probes are threaded into special welded fittings in each line. These electrical-resistance probes sense the coolant and oil temperatures and their ohms resistance is transmitted through DC wiring to the respective instrument in each cockpit to indicate the temperatures. Also on the lower point of a number of oil and glycol tubes, there are welded-in drain ports and, on each oil return line, there are chip detectors threaded into welded tube fittings.

Both entire FWF electrical harnesses have been final installed and attached using Adel clamps and wired in through Cannon plugs to numerous respective locations (generators, starters, tach generators, temperature probes, primers, chip lights, carb air temperature motor controls for induction air temperature, pre-oil, feather pumps, etc.).

Inboard Gear Doors
We have just started manufacturing our two inboard gear doors. These doors are exceptionally complex riveted and spot-welded assemblies. We recovered two extremely munched doors from the Alaska wreck site, not one part was usable. However, the damaged door parts are giving us a huge amount of information on how to manufacture all the new parts and how they go together.  

Completing these two complicated doors will take sometime; we will keep everyone updated on our progress. 

Happy New Year 
Tom, Allison and the 
XP-82 Twin Mustang Restoration Team

Wednesday, December 2, 2015

November XP-82 Twin Mustang Restoration Project Update

Firewall Forwards
Two of the team members have spent the entire month manufacturing replacement lower cowl ribs. These are the ribs that the lower cowling attaches with Dzus fasteners. We had some of the original ribs to use as patterns, but they were totally non-usable due to the aircraft being moved countless times when it was in the field in Ohio.  All of the upper cowl ribs were completed last month, and when the lower ones are completed this month they will all go together for heat treat up to T4 condition (hardened).

Four of the sixteen lower cowl formers

All of the generator and starter firewall forward electrical harnesses have now been fit, cut to length, and their large amperage terminals crimped and soldered on. 

We are in the process of completing the low amperage firewall forward Cannon plug harnesses that go forward and attach to all the miscellaneous electrical components: tach, start and pre-oil relays, generator field, supercharger solenoid, mixture and carb air temperature controls, oil, glycol and carb air temp probes, prop feather and chip detectors. 

Both feather pumps for the MT Propellers are now permanently installed on the left-hand lower firewall armor plate.

Start and pre-oil relays are mounted

MT Propeller feather pump mounted on firewall

Carb Air Temperature (CAT) Control Motors
These two CAT motors have been an ongoing headache. For years, we have tried to find replacements because the originals were open to the weather and full of water for fifty plus years. Both motors, all the sequential limiting switches, and all the wiring and gearing were nothing but a pile of rust and corrosion. We offered this task to one of our wizard volunteers, Gerald. He took this task on to find replacement limit switches (the original style is no longer available), get the motor armatures and fields rewound, and remanufacture all the interior motor and switch mounting brackets. 

Original CAT control motors

He found an electric motor rewind shop that rewound the tiny motors and fields, and repaired the brake assemblies which instantaneously stop the motors at the proper selected positions.  There are four positions for this carb air control system:  ram air, half-hot air, full-hot air, and filtered air. The carburetor air-induction trunks of an aircraft engine must have the ability to control the temperature of the air being forced into the carburetor due to different environmental conditions (temperature and moisture) during flight. The pilot controls this temperature by rotating a switch on the instrument panel to stop the control in each desired position.

All of the limit switch and Cannon plug wiring has now been completed.

One lingering problem was that we could not find the microscopic 16-tooth gears that were on the end of each armature as the originals were rotted away. With much research, Weezie found new ones from Stock Drive Products in New Hyde Park, NY.  

Oil/Fuel Pressure Senders, Oil & Coolant Lines
All four are now permanently attached, Aeroquip-hosed from the engine to the sender, and sender to the firewall. These four NOS Rochester units were contributed to our project by Larry Kelley, B-25 “Panchito.” Thank  you, Larry.  See the article about Larry Kelley’s B-25 Mitchell in the December issue of AOPA Pilot magazine.

The trip to mandrel-bend all of the firewall forward oil and coolant lines scheduled for last month was postponed. Hopefully, the trip and the mandrel bending can be accomplished by the end of December.

Belly Scoops
The final fitting and riveting of the fairing panels have now been completed on the left scoop, along with both forward airfoil attach rails. This fitting has been a complex process to rivet all of the required threaded nut plates for attaching the fairing panels to the lower side of the center section. These nut plates had to be installed between and under the hat channels in the 95-gallon center section fuel tank bays, and a number of them had to be installed in the hydraulic bay compartment in amongst all of the hydraulic lines and components. A fun job, but now finally completed. 

The airfoil support rods for mounting the forward part of each belly scoop

Seats/Armor Plate/Weight & Balance, Center of Gravity (C/G)
The final assembly of all the seat elevation parts is now complete. We have replaced the original steel armor plates with the exact same dimensions using 1/4” aluminum plate . We originally made a decision to wait until we were doing the ‘weight and balance’ of the aircraft to see where we needed to add or subtract weight. The position of the original steel armor plates was so close to the neutral C/G point that it would not make any substantial difference in the center of gravity of the aircraft. 

(When manufacturing and/or restoring any aircraft, one has to be very careful  when it comes to the weight and balance of the finished aircraft.  All aircraft must maintain a specific balance range of inches so that the aircraft flies properly. The ‘weight and balance’ is determined by weighing the aircraft after it is completed to determine where the center of gravity is. The center of gravity can be corrected by adding or taking away factory lead balance weights positioned in the tail.)

Seat rail brackets welded on to the armor plate

From Tom Reilly
& The XP-82 Team