Sunday, August 31, 2014

August XP-82 Twin Mustang Restoration Update

August was an incredible month for accomplishments.

Wings Removed and Fuselages/Center Section Pivoted
This past 15 August the time came to turn the fuselages/center section 90 degrees to the south in our hangar. We used the factory-mounted 45 degree lift points on the inboard side of the center section, right against the fuselage lower longerons. These lift points (¾-16 threaded ports) are designed to bear the entire weight of the aircraft including the engines.  We were able to lift the entire balanced center section with both fuselages and engine mounts with one man lifting and guiding each rear fuselage. The lift and pivot took only about two hours to reposition the aircraft where it would fit out the large south door.

After the lift and pivot, we leveled the aircraft in pitch and roll to within 1/30th of one degree, about the thickness of a piece of cellophane.  We manufactured two vertical steel support pipes to fit into the rear jack points (right forward of the tail wheel attach), and designed them to be vertically adjustable.  At that time we leveled both fuselages on the center section by using the factory shims, and are final-attaching the fuselages to the center section longerons with the remaining six of the twenty internal wrenching NASA bolts. (Longerons are the main beams that are the lower structural rails mounted in the bottom of both fuselages.)

We moved the outboard wing fixture into the hangar and attached the wings to check the washout and made the final microscopic adjustments.

Verticals, Horizontal and Rear Fuselage Extensions
The next day we installed all of trim actuators  in each vertical and the horizontal, (three) and installed all the trim cable pulleys in each vertical. 

We then attached each vertical to its respective side of the horizontal stabilizer. We had to align and hold the verticals in a perfect 90 degree position in relation to the horizontal stabilizer. We used diagonal wires and turnbuckles to make the final tiny adjustments as the verticals are permanently held in place when the aft fuselages are high-shear riveted and bolted to the forward fuselages.

The following Saturday the team built a temporary cushioned wood scaffold and lifted the horizontal/verticals/aft fuselage sections up and forward to within ½ inch of their final attach positions. 

Then came all of the final adjustments to make sure everything was properly aligned prior to drilling and reaming any of the attach holes for the fittings. There were eight exact measurements that had to be aligned:

*  The angle of incidence (the pitch up and down on the horizontal stabilizer in relation to the center section.

*  The alignment of the two vertical stabilizers (toe in, toe out).

*  The exact vertical measurements on the verticals in relation to the horizontal measured between the two top and two bottom rudder hinge points horizontally and diagonally.

*  The exact forward and aft dimension of the center section trailing edge to the leading edge of the horizontal stabilizer.

*  The left and right measurements on the aft fuselage extensions to the forward fuselages. This exact measurement is obtained by shaving the attach fittings of the horizontal stabilizer to the vertical stabilizer.  We intentionally machined all four of them 1/32" thicker to give us extra material if we needed to make small adjustments.

*  The twist of both aft fuselage extensions to align the upper and lower attach points.

*  The vertical attachment of the aft fuselage extensions to the forward fuselage attach points.

*  The alignment of the dorsal fins with the leading edge of the vertical stabilizers.

Everything lined up perfectly.  So then the team started final drilling and reaming all the attachment hardware for the high shear rivets. 

Outboard Wings and Center Section
We completed the riveting of all the top skins while on the fixture, and one more bottom skin on each wing which locked the wings into their final shape.

Both wings are now off the fixture, and the team is completing the final riveting and finishing the fuel cell stand-off angles.

Two of our team members are now fitting and installing the new aileron attach hinge point fittings. One of our machine shops is making the final two outboard flap hinges.

The new inner and center aileron attach hinge point fittings
 are now being installed on both wings.

Two inboard and two outboard ailerons

The final Adel clamping of the wiring harnesses in the center section is now being completed along with the final attachment of the three wiring terminal strips in each wheel well. One of our volunteers is sewing the canvas covers that shield and protect these wiring bundles and terminal strips from dirt and moisture thrown up by the rotating tires on retraction.  Thank you.

The center section nut-plate channels, that attach the fuel tank close-out panels between the outboard wing and center section, are now completed.

Fuel cell stand-off angle installed.

Newly machined forward and aft door lock bell crank
mounts for each main gear door

The new wheels and tires are now installed on the main gear legs

The Katz

"You will not get into this rivet case until I get my treats!"     --- Allison


Friday, August 1, 2014

July Restoration Update

It was a very interesting month

A lot of to-complete projects on both wings are being done, i.e., flap and aileron hinges, drop tank pressure and feed lines, de-ice hot air discharge vents (14), countersinking the remaining lower skins, aileron trim jack screws, etc., etc.

Drop tank  pressure and fuel feel lines

Riveting the de-ice hot air discharge vents in the lower skins of both wings.  
There are fourteen of them.

Vertical Stabilizers
Both vertical stabilizers are now completed, less the side skins that must be left off to gain access for alignment and fitting. Each vertical needed its lower skin riveting completed. Both verticals are awaiting mounting to the horizontal stabilizer and then to the aft fuselages.  All of the trim tab (rudder and elevator) pulley brackets have been installed along with all of the closeout panel, fairing and tip nut plates. The alignment, final installation and riveting of the four rudder trailing edge hinge points are now completed on each vertical. 

The two aft jack points are now installed along with the gap seal extrusions in the vertical stabilizer-to-rudder bays. 

One of the two wood-forming blocks for the vertical tip cap has also been completed, awaiting the forming of two new vertical tip caps out of 5052-0 aluminum.

Vertical Stabilizers to Aft Fuselage Attachments
The special angles (four) have now been final fitted and drilled and reamed for the attaching 5/16” and 3/8” nut plates and close-tolerance bolts. The excess skin overlap on both aft fuselages has now been flush trimmed to accept the zero-tolerance butt-fit of the four vertical stabilizer side skins (two per vertical). 

Wheels and Tires
The new Michelin Air 32 x 8.8” tires have now been mounted on our new wheels. We had to lathe out of a piece of billet two new inner-bearing and seal spacers. None of the original ones that we had from the Soplata or the Alaska wreck site were salvageable due to deep rust pits. 

Heat Exchangers / Cooling System
One of our machine shops has completed the remainder of the brass water neck and purge fittings that get soldered on to the shell(s) of each heat exchanger. (For a size reference, the diameter of the large flanges is about 6”.)

Another one of our shops completed the sewing of the chafe straps (10) for the oil and glycol header tanks.  Thank you, all.

As mentioned in the previous news release, the two center windshield glasses are now completed and fit. The four side glasses have been sent out to an aviation Plexiglass-forming company in Ohio. We hope to have these back soon.

The Katz - It’s Hot!
“Would you be so kind to let everyone know as they pass the water cooler, to push the cold water button.  Thanks.”
-- Rivet


Monday, June 30, 2014

June XP-82 Restoration Update

Wings/Center Section
The crew completed the left-hand leading edge and final riveted it to the forward spar of the left-hand wing.

Left-hand Wing

The remainder of the top inboard skins are now completed through their structural high-shear riveting (special collared steel rivets through the wing-attach angles and stringers).  On both wings, the crew has three of the four top skins completed along with the two lower inboard skins at the attach angles. 

We chose to use the center section as the parent fixture for the attachment of the wing-attach angles and the riveting of these upper and lower inboard skins to lock everything in place on sweep and dihedral. The two wings will come off during the second week of July and go into the fixtures for final adjustment and to confirm washout (the downward twist of the outboard section of the wings). 

Lower and Upper Views of the Right-hand Wing

Hydraulic, Instrumentation and Brake Lines
The majority of the lines running along both cockpit floors and up behind and through each firewall are now completed. It has been difficult attempting to duplicate the exact routing of each line as most of them had been removed during the disassembly of the fuselage from the center section in the early l950s.  We were able to get the routing accurate by observing the through-fittings in the center section floor and the line mounts on each longeron. The drawings we have depicted the “B” and later model fuselages, a number of them having the same routing as our XP. 

The overhauled hydraulic firewall-mounted tank has now been completed, including the fuselage suction feed/return and pressure lines. 

Left-hand cockpit prior to final Adel clamping

Completed right-hand cockpit less master cylinders

Hydraulic tank with new hydraulic quick disconnect now mounted to firewall

We have been restoring the seats and the question came up as to whether we are going to use the original steel armor plate or replace with .437 (7/16”) aluminum plate for weight savings. We have two original steel armor plate panels that can be easily welded, surface ground and repainted.  Where the airplane comes in on weight and balance will make the decision for us.

One of our machine shops completed the two
 XP non-boosted aileron hinge points. 
The left-hand pair show the two separated subcomponents.

The left-hand aileron acme screw trim tab control box and bronze chain sprocket 
are now completed.

Parts Find
The first week of June I received a call from a man in Mint Hill, NC, just south of Charlotte, who had purchased a P-40 project from Ms. Janie Odgers, the family from whom we had bought from the remains of the crashed F-82H out of Fairbanks, AK. Richard Odgers, the now deceased husband, was too ill back in 2008 to travel to Anchorage to complete the sorting of the F-82 parts from the P-40 parts that he had in his warehouse.  Brent VanDervort, whose business is a large hot rod fabrication facility, purchased the P-40 project along with a small cache of F-82 parts.

I made a trip to Charlotte last week to examine what he had and, he had a number of important parts that we were still missing, i.e., four throttle quadrant cable quick disconnects and throttle handle, pilot’s glare shield gun site mount, one leading edge .50 caliber gun barrel fairing and blast tube, and a number of other small pieces of gold.  He declined my offer to pay him and said these parts were supposed to come to us six years ago. 

If anyone is contemplating building a street rod, his company is Fat Man Fabrication, Mint Hill, NC. One cannot believe the quality and the massive amount of different parts that his factory manufactures for the street rod business. Thank you, Brent.

One of the six center section leading edge machine gun ports 
and .50 cal cooling blast tubes.

Pilot's knurled throttle quadrant handle

The last four NAA throttle quadrant cable quick disconnects
that we still needed to complete our cabling.

A Special Visitor
Mr. Jim Sampson, a retired USAF Alaska F-82H pilot from 1946 - 1949, gave us a very nice visit last week. He is the youngest and most agile 93-year-old I have ever met in my life. He could remember flight details, i.e., air speeds, manifold pressures, climb rates, as if it were yesterday. He was very impressed with our restoration and promises to come back on a regular basis.  Thank you, Mr. Sampson, for your USAF service.

Mr. Jim Sampson and Tom

The Katz

Allison selecting a bolt

Allison's Selection of Bolts

"I don't think that the Rockwell hardness on this bolt
 is good enough as I can bite into it." -- Allison


Sunday, June 1, 2014

May XP-82 Twin Mustang Restoration Project Update

The team has been completing the hydraulic and instrumentation lines in the two fuselages. There is a massive amount of these hydraulic and instrumentation lines running through the center section up through the floors and to both instrument panels. Along with this multitude of aluminum tubing, the team has been synchronizing all of the levers on both throttle and propeller quadrants.  The installation of the static lines (neutral air pressure) has now been completed and the lines run to the three locations (two in the left and one in the right fuselage).

Static lines in the left-hand fuselage

Fuel pressure, oil pressure, manifold pressure, airspeed and static lines, along with the parking brake valve in the left-hand fuselage

The hydraulic lines under the pilot’s floorboards that run among the coolant tubes has been somewhat of an issue reinstalling them exactly the way the prototype had them.  In the production airplanes, they were routed in a much more logical order, not that our duplicating the original has caused any problems that we were not able to over come.

Floor hydraulic lines prior to Adel clamp mounting

The team also completed all of the flap hydraulic lines that run out the trailing edge of the center section and attach to the flap hydraulic cylinders that are mounted on top of the center section underneath both fuselages.  The flap lines run from the flap hydraulic selector that is mounted aft of the left-hand center section wheel well to the center of the gun bay, then aft to the rear of the center spar.  They then split and two lines on each side run out to the retract cylinders that are mounted on the underside of both left and right fuselages.  

NAA had a unique way of installing flexing lines on both the two main retract cylinders and the two flap cylinders.  Instead of having a swivel joint, they just bent the hydraulic line(s) in a 360 or 720 degree flex circle, depending on the amount of flex that each cylinder would exert on the line.

Flap cylinder (upper) and aft spar hydraulic lines (below)

There have been comments on our website and/or Facebook as to why we are using AN fittings.  On our XP-82 and all subsequent production versions of the F-82s, North American used all AN fittings which replaced the Curtiss (A/C) fittings that were used on all previous North American products.  

Curtiss on the left; AN on the right

On our aircraft, the prototype, North American had put in four static port holes in the fuselages to find the zero pressure area for the static ports. We have duplicated these test static holes for originality.

Canopies and Windshields
Both canopies are now totally finished and all of the canopy trucks are completed and ready to be installed.  The two glare shields (pilot and, co-pilot) and armor center windshield panels are now completed awaiting the forming of the side glasses. 

New machined canopy truck

There has been just about a full team effort to complete our two wings. The team has completed the riveting of the leading edge as a subassembly and all of the aluminum lines are now installed.  These consist of electrical conduit tubes, aileron cable guidance tubes, pitot lines, drop tank pressure and return fuel feed tubes, boost pump, liquidometer, strobe, tip lights and pitot heat conduit tubes.  The bottom inboard skins on the right hand wing are now completed awaiting the closeout panels.

Every top and bottom skin on the left-hand wing is now completed with all of the dimpling, counter-sinking and edge fitting.  Also being completed is the left-hand leading edge and the four  top  wing skins for the left-hand wing which are being riveted this week.

Newly formed left-hand leading edge bow

Right-hand wing

Aluminum tubes and wiring in the left-hand wing leading edge

Subcontract Machine Shop
All of the aileron and flap hinges are well on their way to being completed, and the aileron sectors are also in process. The last large machine shop items to complete will be the four secondary engine mount structures. These large pieces are shaped like a T platform and bolt to the Merlin engine mount pads. These are not complicated pieces to make.

The large exopy-cast tooling mold that we made a couple of months ago is now completed with its ½” steel welded containment structure to support the bottom and sides. When we press the stainless steel into the mold, we’ll apply over 200 tons of pressure.  With the ½” steel structure surrounding the epoxy mold, the press will not shatter the epoxy.

The Katz
After a relaxing two weeks at the beach, the Katz are back and trying to find a cool spot to hang out.