Monday, April 4, 2016

March XP-82 Twin Mustang

 Firewall Forwards (FWFs)
All of the upper cowling hat channel ribs have been completed and final fit. Three team members have been reworking the original firewall forward left-hand engine LH and RH top/side panels that go from the firewall to the propeller, one on each side, that came with the original purchase of XP-82. They had been out in the weather for years with countless pieces of steel and aluminum stacked on them, introducing numerous dents and scratches.  The team members have been English wheeling these dents out of the surfaces and burnishing out the scratches.

Original top engine cowl (right-hand)

We received back two full sets of new 4130 steel cowling latches. We had to order two complete sets, one for each engine, as all of the original steel parts were rusted beyond repair. These parts had to be sent for heat-treating to be brought up to the proper hardness and then on to cadmium plating. 

Cowl latches

The two NOS generator cores were just received back in overhauled condition from Aero Accessories in San Antonio, TX. Each one will have been installed on each engine by the time you read this.

All of the 28-volt FWF wiring harnesses, fuel/oil/manifold pressure/vapor return and vacuum lines are totally completed on both engines.

We also had to have two special  30° offset #16 (1”) carburetor inlet fuel fittings machined. These two fuel fittings adapt the upgraded Aeroquip 302A-16 fire-resistant hoses running from the engine-driven fuel pumps back to the carburetors.

Wing Center Section Leading Edge
A lot of work has been going into the leading edge stainless steel gun ports (six). We had two out of the Alaska wreck site that were basically undamaged. We also had two that were partially damaged and able to be salvaged, with two having to be formed and welded from scratch. This is a complicated procedure as they must precisely fit the new-formed leading edge.

Leading edge gun ports just starting to be fit

Tail Wheel Assemblies
We are about 90% finished with the two tail wheel assemblies with about another 90% to go. These are extremely complicated mechanisms that have at least a thousand moving parts. We have about 20 parts left that have to be machined and still must go to heat treat and/or cadmium plating.

The new tires and tail wheel tubes have been mounted on the two tail wheel assemblies awaiting final mounting when the axles return from cadmium plating.

We are having the tail wheel door skins (four) pressed as we speak.

.50 Caliber Machine Guns
The final fitting of the six .50 caliber replica machine guns is advancing along well. We were able to purchase all of the ammunition we need from a machine gun dealer friend. We have even gone as far as finding original 1943 date code armor-piercing, empty powder ammunition with live primers and black tip (armor-piercing designation) bullets. What we must do for authenticity is polish off the black tip on four out of five original projectiles and dip the tip of one of every five linked cartridges into an orange-red paint to designate a tracer round. This way, out of five linked cartridges, #1 will be armor-piercing, #2 will be a tracer, and #3, #4 and #5 will be standard ball ammunition.      

We have also gone to the extent of installing original .50 caliber barrels and cooling jackets so that when one looks into the leading edge of the wing center section, they will be able to see the rifling in the barrels.

The armament specialist that we have hired is progressing nicely on fitting the feed chutes and link ejector discharge chutes. All six guns have been temporarily installed for final fitting.

Six .50 caliber machine guns mounted looking aft.
One can see the gun heater and firing wires
coiled up prior to routing and hook-up.

The Kat
Allison just returned from Spring Break.


Wednesday, March 2, 2016

February XP-82 Twin Mustang Restoration Newsletter & Photography

Firewalls Forward (FWF)
We are progressing very well with the multitude of FWF tasks. The remaining FWF tasks to complete are as follows: both oil feed lines (one from each oil tank), one glycol coolant return line to each firewall, one oil return line from each engine to heat exchangers and generators.

Engine Cowlings
Each engine has three lower Dzus cowls. Both lower forward cowls are now complete and both second-from-the-forward cowls are nearing completion. All of these cowls have compound shapes requiring English-wheel forming. 

English wheel used for forming compound bends

Completed lower forward cowling

All of the ram air cooling blast tubes are now formed and awaiting installation.

Both engine-driven fuel pumps and left engine hydraulic pump tubing and hoses are completed (the XP-82 has only one hydraulic pump fitted).  Not an issue as the landing gear will free-fall and positive lock down.

Fuel Systems

All six fuel tanks, 600 gallons total, are now completely installed including boost pumps, fuel shut-offs, check valves, cross-flow valves, scuppers, etc., and are awaiting filling with AV gas to test each for leaks. With 600 gallons of internal fuel, the XP-82 (Merlin-powered) burns 100 gallons per hour at 300 mph cruise speed, giving it an 1800-mile range. With four 300-gallon drop tanks added, 5000 miles maximum. 

Firewall Aft Coolant System

Every coolant line from both radiators and spherical header tanks running forward to each firewall is now totally installed. A substantial job, the same as doing two complete P-51 cooling systems.

Electrical Systems
We are about a month away from completing the last few outstanding items on the electrical system. At that time we will put power on the ship for the first time to check out each system. A huge “thank you” goes out to Concorde Battery Corporation for contributing their best maintenance-free 24-volt battery. (I had one in my B-25 Mitchell and it lasted only nine years! Unbelievable!)

Inboard Gear Doors
Both inboard gear door frames are now with one of our subcontract machine shops being fitted to the large aluminum press dies to press the complicated inboard door skins.

Also, another huge “thank you” to Thrush Aircraft,  manufacturer of the best agricultural spray aircraft, for the heat-treat processing of hundreds of cowling and gear door parts for us.

Guns/Barrels/Cooling Jackets
We purchased the six cooling jackets that thread into the forward part of each .50 caliber receiver. The six original .50 caliber barrels that we have also screw into a separate set of threads in the receivers.

Fourth from left shows .50 caliber barrel inside the cooling jacket

Tail Wheel Assemblies
These tail wheel assemblies must have been designed by Rube Goldberg. They have an amazing amount of moving parts just to retract, steer and lock. Even though the majority of the parts were not damaged due to the Alaska impact crash from where we recovered the parts, most were non-airworthy due to being under water for sixty years. I am making a good headway and plan on having both installed, one in each aft fuselage, within a couple of months.

Partially assembled retractable, steerable and locking tail wheel unit prior to finish coats of Imron paint. 
Only about half of the parts for one unit are showing in this picture.

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