Wednesday, July 1, 2015

June XP-82 Twin Mustang Restoration Project Update

Once again, we had a fabulous month 
with lots of progress.

Wing Trailing Edges
The final trimming of the upper and lower skins on both wing trailing edges is now completed. These trailing edges hold extruded stiffeners that act as a secondary gap seal for the ailerons. The primary gap seal is a full-length sewn rectangular canvas panel that attaches to both the trailing edge spar, and the leading edge on each aileron. This gap seal stops the airflow from the lower airfoil of the wing up through the leading edge of the aileron. If allowed this airflow would disturb the effectiveness of the aileron.  The wing crew has these trailing edge extrusions completely fit on the left-hand wing, and the fitting is almost completed on the right-hand wing.


Inboard wing flap hinge and lower trailing edge flap bay ribs


Aileron extruded stiffeners


Aileron control cables installed in bell crank

Fuel Tanks, Vent Lines, and Fuel Tank Liners
The fuel tanks have been delivered. A beautiful job from Eagle River Custom Shop located in Eagle River, WI.  They fit like a glove (not to be confused with O.J. Simpson’s leather glove). The final fitting of the fuel tank liners involves matching all of their multiple access holes for the fuel pumps, liquidometers, vent lines, fuel feed lines to the existing holes in the center section and wings.

The fuel vent lines in both outboard wing bays are complete and the vent lines in the center section fuel tank bays will be installed when the final mandrel bending is completed this July.



 Fuel vent lines installed in the outboard right-hand wing bay

Tail Wheel Retract and Steering Mechanisms
Two of our subcontract machine shops have been busy making numerous tail wheel assembly parts that were not salvageable.  They still have about 25 part numbers still to go, and when those parts are delivered, we can start on the final assembly of both tail wheel retract assemblies. 


Coolant Exit Doors,  Tunnels, and Radiators
The sheet metal crew have completed both coolant exit doors and have fit them into the tunnels. As mentioned in past news releases, these exit doors, even though they appeared very simple to repair and duplicate, had caused a substantial amount of problems due to numerous skins having compound bends in three different directions.  We have installed the right-hand radiator.


Original coolant exit door




 Completed coolant exit doors


Aft view of the right-hand radiator installed in the tunnel


 Side view of the right-hand radiator installed. The reflection is from a
temporary piece of protective plexiglass.

Rudders
Both rudders are now completely installed along with the multitude of trim cables and chains. The synchronization of the pilot and co-pilot rudder trims is accomplished by numerous cables and chains that run through the horizontal stabilizer and then attach to each rudder jack screw assembly, one mounted in each vertical stabilizer. 


Installation of the right-hand rudder



Both rudders are now installed

Merlin Engine Installations
We are getting very close on our engine installation schedule for both engines to come out of their sealed nitrogen-filled containers and see the light of day again. 

One of our machine shops is in the process of machining the twelve required Dynafocal vibration-insulating mounts. These mounts are very close to but not the exact dimensions as the P-51 Mustang series.

We have found a company that makes aircraft mounts that has agreed to pour (actually force feed the molten rubber) into the newly machined  Dynafocals mounted in mold housings.



 Original engine Dynafocal mount in its exterior aluminum housing

When these twelve Dynafocals are completed, both engines will be installed in their associated mounts.

Note: 
Our XP-82 Twin Mustang, #44-83887, was the first XP-82 to fly.  On the very first test flight, the counter-rotating left-hand turning engine was mounted on the left-hand fuselage, and the right-hand turning engine was mounted on the right-hand fuselage.  This arrangement created an upward sweep of the propellers’ wash over the center section, creating an aerodynamic stall (loss of lift). The aircraft would hardly fly due to the loss of lift over the center section. It is a well known fact, including countless photos published by North American, that there was only one flight, our aircraft #44-83887, with the props upsweeping. Before any second flight, the engineers at North American decided to swap the firewall forwards (engines and props) to create a down sweep that cured the center section stall situation. All of the remaining 271 Twin Mustangs built, including our XP-82, had their engines installed with the right-hand turner on the left-hand fuselage and counter-rotating left-hand turner on the right-hand fuselage. 


We will install our engines the same way--with the right-hand turner on the left-hand fuselage and left-hand turner on the right-hand fuselage.


A picture of our aircraft #44-83887 prior to its first flight with the left-hand turner on the left-hand fuselage and the right-hand turner on the right-hand fuselage with upsweeping props. This propeller configuration is what created the unacceptable stall situation on our aircraft.


Still have not heard from Rivet.
We all miss her, especially me, Allison.




The XP-82 crew wishes everyone a
Safe and Happy 4th of July!



Thankx
Tom



Tuesday, June 2, 2015

May XP-82 Twin Mustang Restoration Project Newsletter & Photos



May was a great month with lots of progress on our XP-82

Center Section
Two team members completed the last of the hydraulic and instrument line hookups, i.e., final brake, pitot, static, vacuum, and electrical conduit lines.  They also completed the installation of the last hydraulic component that we were missing, a relief unloader valve. This component signals the engine driven hydraulic pump to go into neutral when there is no hydraulic demand on the system, i.e., gear or flaps requiring hydraulic pressure. 

We were able to find a number of the hydraulic valves online, two were listed as “used - as removed” for $50 each, with new ones in the range of $1500 each. We bought two used ones and when they arrived, they were obviously new units that had never been installed. The sellers listed them “as removed” to avoid any liability issues. We still had to take one apart and re-“O”-ring and reseal it just for a safety factor.



Center Section Flap/Gap Seal
The final fitting of the phenolic upper gap seal rub strip is now completed. The installed flap in the retracted position is designed to rub its upper stainless steel rub-skin against this phenolic strip to stop any inflight air flow from the lower center section to transition through the leading edge to the top of the flap skin, creating an undesirable aerodynamic condition.



Elevator
The final fitting of the elevator mounted on the back of the horizontal stabilizer has now been completed. We are in the middle of adding the extra lead balance weights to the elevator arms to counter balance the additional weight of the aluminum trim tab hinge fittings. We replaced the original magnesium fittings with ones made from 7075 T-6 aluminum for an additional strength safety margin. The original magnesium fittings have been known to fail, creating fatal accidents.



Fuel Tanks
Our six new fuel tanks, 600 gallons total, are now completed and we will take delivery of them during the month of June. They were manufactured for us by Eagle Manufacturing Corporation/The Custom Shop in Eagle River, WI. These tanks were very professionally done. Thank you for the excellent job.



Aileron Hinges / Bell Cranks / Wing Trailing Edges
All of the aileron hinges and associated bell cranks/arms/mounting points are now completed and final installed.  Now that the ailerons and all of their mounts are completed, two team members have started on the wing trailing edges in the aileron and flap bay areas. These upper and lower wing trailing edge skins must be precisely fit so the ailerons and flaps slightly rub them to create a gap seal (the same as on the center section flap).


Right-hand aileron attach hinge and bell crank installed


Right-hand outboard aileron attach hinge


Left-hand aileron attach hinge and bell crank installed

Subcontract Machine Work
We received back from one of our machine shops four gear door up-lock forgings. We were able to recover only one that was severely corroded, but good enough for a pattern. These were extremely complicated pieces to machine, but they came out perfect.


Coolant Exit Doors
Something so simple as fitting some new pressed internal skins to the original frame work sure became an issue which took a substantial amount of time to finally get it correct. The fit of the new parts was oh so close, but not close enough. It took two team members the majority of the month of May to get these issues with the two doors finally worked out.


Fuel Vent Lines
We are heavy into the installation of all the fuel feed and vent lines in each wing and center section. We expect to have all of these lines fitted by mid June. And then the six fuel tanks can start to be installed.


New vent and fuel feed lines along with some of the original patterns

The Katz – Very Sad News
Rivet, our beloved gray companion for many years, disappeared four weeks ago this past Thursday. She was safely secured in the large hangar Wednesday evening, and when the B-17 crew opened the hangar the next morning they saw her. We have opened every door to every room in all three hangars, opened every shipping container, looked in every box that she might have fallen down into, all numerous times with no luck. We have also checked many times with Douglas Animal Control, the city pound, and everyone else we could think of.  We don’t think a coyote got her. We are almost positive that no one took her as she was very hesitant to be around strangers.  So, we all hope that she will show up somewhere and we can possibly get her back.  Allison and the XP-82 crew miss her.


Thanks.
Tom

Friday, May 1, 2015

April XP-82 Twin Mustang Restoration Update



What a month it has been.

It seems that we can work on some specific systems for months, and it never seems to get done. Well, this month quite a few of these endless jobs got completed. 

Windshields
Both windshields are now completed with all their glass panels installed with PRC (epoxy) edge sealants and mounted on each fuselage. The last thing that needs to be completed is the special rubber seal inside the windshield bow that seals the canopy to the bow when the canopy is closed.



Ailerons
Both skinned ailerons and bell cranks on the right-hand wing are now complete and final-fitted on all of their hinges. Both ailerons (two per wing) and all the mechanisms operate as smooth as silk.

The final fitting of the two main XP attach fittings in the left-hand ailerons is now complete. As mentioned over the past few months, the fitting of the remaining aileron hinges is progressing quite rapidly as the “reinvention of the wheel” was completed on the right-hand wing.  Designing, manufacturing and final fitting the new non-boosted XP hinge points to the boosted “E” model ailerons was quite a brain-burn.   Two of our  lead sheet  metal  crew  took on the challenge and made the tasks look simple. We expect both left-hand ailerons to be completed mid May, and the final skinning of the bottom of both wings will begin.


Right-hand ailerons are now complete


Final fitting of the left-hand aileron attach fittings


Aileron fitting for the left-hand aileron

Gear Door Retract/Door Up-Lock Hook Cylinders
Mounting of the overhauled cylinders with their coiled flex aluminum lines was a very difficult fit, not allowing anything to rub.  Both are now completed.



Fuel Tank Feed & Vent Lines/Tubes
These tubes are projected to be complete by mid May. Two team members spent two weeks forming patterns out of malleable tubing that were sent out with the new tubing (multiple sizes of 5052-0) to be formed. These tubes must be formed (bent) with a special mandrel machine bender or they will kink. I purchased a mandrel bender a year ago that hadn’t been assembled or used for years. This is a very large heavy manually operated bending machine that is 15’ long and weighs more than a thousand pounds.  I loaned the machine and all of its forming dies to Gerald, one  of  our  volunteers,  who lives in Mississippi. Gerald is a retired Naval officer, radar expert and a EC121 (Connie), P2V  Neptune and P3 Orion crew and driver (pilot).  He spent weeks repairing all of the parts of this machine (lots) and is now forming all of our fuel feed and vent aluminum tubing.  Thank you, Gerald.

Seats
We assembled the pilot and co-pilot fold-back seats. (Each seat can fold back and the rudder pedals disconnect to slide forward so either pilot could sleep on long missions.) These went together quite quickly as we have had all of the parts detailed and waiting for assembly for a few months.


Tail Wheel Assemblies
Two team members have started on the two massively complicated tail wheel retract assemblies. There are literally hundreds of moving parts in these retractable and steerable units. Fortunately, we now have almost all of the parts, and two of our machine shops are completing the last few items that we are missing.  


North American Aviation Drawing of the Tail Wheel Retraction Assembly


Newly machined tail wheel assembly parts

Coolant Exit Doors
We got the two interior skins for the exit doors  pressed. They were a very difficult pressing because each had a combination of concave and convex shapes, making them very challenging to form on an English wheel.  We now have them both fitted to the internal framework and exterior skins, and have test-fitted both to their respective fuselage coolant exit door tunnels. We expect both of these to be completed and mounted by this summer.


Pressed interior coolant exit door skin


One of the assembled coolant exit doors


Test fitting one of the coolant exit doors in the fuselage tunnel



The center section gun bay door and two ammo bay doors are now complete


The two flap tubes and attach arms, one of each under each fuselage mounted on the spar, are now assembled and permanently installed.


The right-hand cockpit set of rudder pedals and adjusters is now installed.


The left-hand tee forging to synchronize the pilot/co-pilot elevator sticks is now installed. The pilot and co-pilot control sticks and associated plush rods are now permanently installed.


The final fitting and riveting of the two dorsal fins is now complete.


Tom's Birthday Celebration went way too late into the evening last night.


Cute "Egg" model of the F-82

Thankx
Tom