samparfitt

My Feedback: (43)

Booms (cont)

In order to plank the inside of the left boom, I removed it from the wing and stab.
I mirrored the inside planking using the same basic dimensions as on the outside.
First, I cut out the servo access hatch to string the servo extension wires to the servo area.
Epoxy used, again, to adhere all planking.
Water was applied to the outside back sheeting to get it to bend as well as the two pieces that were glued on the center wing.

pic 1:
Boom planking over the center wing sheeted.

pic 2:
The center wing TE's inner edge has to be trimmed so the boom sheeting can be glued and also doesn't interfere when the wing is removed.

pic 3:
Removed boom from center wing and stab so the inside can be planked.
Front short piece of sheeting added first.

pic 4-6:
Next was the nearly 4' long sheeting over the back top/side of the boom.
Some long cuts needed in the sheeting to cover the compound curve in pic 6.
pic 7:
Triangular piece of sheeting needed to finish the top center of the boom.

pic 8:
Fin fillet epoxied to fin.

pic 9-11:
Took the left boom out to the shop to sand all the sheeting (planking).
The last picture has a good view of NS-1; the interface ply between the fin and stab.

samparfitt

My Feedback: (43)

Booms (cont)

The left boom was mounted back on the center wing and stab and planking of the right boom is the FINAL sheeting (Yeh).
The same sequence will be used to plank the right boom.

pic 1:
Servo hatch cut out of left boom and wires stored while planking was done on the left boom.

pic 2-7:
Left boom back on the center wing and stab.

pic 8:
Right boom planking over the front of the center wing using the same paper template that was used on the left side.

pic 9:
Ready to plank the right side.
It goes pretty fast since only two main sheets are used and the epoxy dries fast.

We're suppose to get 6-8" of snow in the next twelve hours: guess that I'll just have to stay in the basement and 'build'!

samparfitt

My Feedback: (43)

Booms (cont)

Planking (cont):
Right boom top stringers added and half the top was sheeted.

pic 1:
Stringers epoxied to the right boom.

pic 2:
The right front section sheeted.

pic 3-5:
The rear top done.

pic 6:
The short section over the center wing completed.

samparfitt

My Feedback: (43)

Booms (cont)

Planking (cont)

With 3/4 of the boom planked, I can safely remove it from the center wing and stab without fear of any warping.
The final planking on the inside of the right boom completed.
To me, it's a major time mark when all planking is done.
Next will be to bondo the booms, put the 'bubbles' on the gear doors, glass, make FG copies of the doors and cut the doors out so I can finally put her on her 'legs'.

pic 1-3:
Right boom removed and final sheeting completed.

pic 4-6:
Out to the shop for the surface sanding.

pic 7:
We got about 5-6" of snow.
Pretty cool: looks like Christmas morning on 'Christmas story'.

Flakbait

My Feedback: (20)

Sam,

Looking good !!!!
You are a MACHINE !!!!

simple

My Feedback: (9)

Sam,

I have had the opportunity to be around both types of construction -

a. Single construction (which mine is)
b. Component assembly

You are exactly correct - the versions that disassemble can be handled by a single person and the wing and boom permanent mount is a bear to move around. I can just manage loading and unloading on my own with the wing tips off.

Anything other than loading for transport such as flipping it over or working on the more complex systems requires a ground crew. My P-38 is component assembly and in the years I have owned it I have only pulled it apart once. So when the time came for the P-61 I decided to go with single construction thinking I would never pull it apart either. (wrong)

Recently, I took mine to an IMAA event and learned a new lesson. For transport inside my SUV I have always "capped" the fuel vent lines to reduce fumes inside the vehicle. Well, this time I removed the plane from my 72 degree garage and drove it to the field in a 72 degree SUV early in the morning. The temperature at the field was 42 degrees and when I removed the plane and set it on the table in the pits within a few minutes I heard a muffled "pop" followed by the hissing sound of pressurized air, two minutes later I heard the same thing.

The retracts were still showing pressure so I investigated further - Turns out it was the fuel tanks rupturing as they imploded - because I still had the vent lines capped off for transport, the drastic temperature changed caused the tanks to contract and split at the cap openings . Extreme temperature changes are just not a usual for the Arizona environment. Anyway, I did have two replacement tanks with me - so with a pit crew we removed the gear, pulled the tanks and replaced them - the whole time, half the pit crew was being utilized to just hold or move the plane around.

I would not choose the single wing/boom construction method again for a plane intended to fly vs display in a museum.

(P.S.) It was a lot of work to replace the tanks and we only got one flight in for the weekend but Widow Maker did win 3 awards for Best Finish, Best Multi-Engine and Best Military

"Build it and they will come"

samparfitt

My Feedback: (43)

Flakbait:
thanks, dude.

David,
Well, that's another good reason for 'component assembly'.
The way your P-61 looks, I can see why it took lots of awards.
If mine looks half that good, I'll be happy!

====================
Glassing prep.

With all the planking done on the booms, it's time to get them prep'ed for glassing.
I roughed up the interiors edges of the ABS white plastic gear blisters to give some 'tooth' for the epoxy.
I also sanded a taper along the outside edge before epoxing/taping the blisters to the doors.
The front edge of the blisters go right above the center former support of the door so I just stuck a straight pin in from the inside to get this location as well as using straight pins at each end to get the center of the doors. I put tick marks at the center ends of each blister so the blisters would be aligned with the middle of the doors.
Next was using evercoats 'easy sand' two part bondo to fill in all the imperfections on the booms.
After sanding the booms out in the shop, I then cut some 1 oz FG cloth for the booms.
Being 3' wide cloth, I first covered the bottoms from the front backwards.
I used zaps finishing resin, a bondo applicator, an acid brush and lots of 2" square paper towels.

pic 1:
The gear blisters epoxied over the doors.
The back of the blisters overhang the booms for a few inches.

pic 2/3:
Everycoat 'easy sand' applied and then sanded out in the shop.
Most of the imperfections are filled in: after glassing and priming, the remainder imperfections will be filled in.

pic 4/5:
Ziroli's 1 oz FG cloth put along the bottom of each boom.

pic 6/7:
Finishing resin applied.
The booms were too big to do both of them on the cardboard so I transferred one to the build table and then did the second one.

samparfitt

My Feedback: (43)

Glassing (cont)

pic 1/2:
Finished up glassing the bottom of the booms.

samparfitt

My Feedback: (43)

Glassing (cont)

Finished up glassing the top of the booms and fins.
When I was glassing the bottom of the booms, the cloth also covered much of the top of the boom so there wasn't much cloth needed on finishing the booms. I used one piece of cloth for the fins and wrapped it around the LE.
I need to finish up the rudders, make FG copies of the gear doors and then install the gears.
I'll also get started on the main service tray, which will be in the center of the center fuse.
With the service tray built, I'll be able to get a permanent install of the 'brains' of the plane.
The service tray will be screwed to the center wing so it will be removable.

G-Pete

Nice, any pictures?

questions about the tanks. Would a removable firewall make more sense for maintenance? How often do you check your fuel system?

samparfitt

My Feedback: (43)

G-Pete,
I know your question is directed to David, but with removable parts, the tanks will be real easy to get to.
Before each flying season seems a reasonable time to PM everything in a plane: sooner is your plane 'starts talking to you'!

===========
pic 1:
I LIED!
While doing the previous post, I realized that I still had those four small balsa sheet areas on the center wing to glass.
NOW, I'm done!

G-Pete

Sam, the question was directed to David. He stated it was a lot of work and it resulted he got only one flight.


There are only four P-61 around worldwide, three of them are on static display ONE of them will FLY again.

[link=http://www.maam.org/p61/p61_rest.htm]Click here for this [/link] amazing project. Also they have some cool merchandise [link=http://www.maam.org/php/xcart/P-61-MERCHANDISE-p-1-c-273.html]click here for shirts and stuff[/link]

have fun browsing that site - very interesting and educating.

simple

My Feedback: (9)

G-Pete,

How is that night fighter of yours coming along, is it ready for the season yet?

Yes - removable firewalls are the stuff dreams are made of if you think about it first in the build The B-25 I had at WOR last year was the first twin I had with removables and I decided that I would always do that in the future on my twins but it was too late in the game for the p61 or P38.

I do a full maintenance run once a year on the 38 but I don't fully disassemble it. I have a set of stands and I just slightly separate the booms from the center pod enough to pull the tanks and check the clunk, make sure the retract connections are good and the electronics are clean. 2 years ago I started using black fuel line in my tanks which lasts longer with the new fuel additives.

The only time I have done a complete disassemble was when I replaced the G-38's with DA50's.

Sam, I will be working on the 61 later today and will be removing the cowl - I will take a few shots of the exhaust and post it.

G-Pete

The paint I've done last weekend - some weathering on the radar pod and nose - she is ready to go... If Sam comes out to the Warbirds over the Rockies (I bugged him before) we can all fly together. This year there will be a ton of twins attend...

samparfitt

My Feedback: (43)

Glassing (cont)

pic 1-5:
Took the booms and center wing out to the shop and hand sanded all the FG.

kram

My Feedback: (7)

Grrrrrreattt! We all go to WOTR and fly twins, I'm gonna look like the demolition derby king compared to all y'all's museum quality Ferrari's!

Sam, I know (as a thread starter myself) that we all kinda get charged up from the comments that other guys add to your thread. That may be a bit of a problem for you, because a lot of us (well, me at least) are sitting here with our mouths agape at your speed and stamina. Don't let this awed silence discourage you. We ARE still watching. Faithful daily subscribers. And I can honestly say that I haven't seen anything that moved me to comment on how it could be done better. Yet

Keep up the good work. I can't wait to see your first flight report. This baby is like a friendly P-38: powerful, yet stable.



mt

simple

My Feedback: (9)

Sam, here are a couple of shots of the in-cowl muffler with top exiting exhaust.

Like I said its not pretty but it gets the job done. Several of the clubs here have noise limits that are enforced and these actually get the job done while providing performance and a great sound.

The image also shows the last coat of paint being applied to the final surface colors - I used my cell phone so its hard to tell but the way the paint was applied can be seen on the tape.

Also I just got a great email referencing aircraft on Iwo Jima and there were a couple good quality shots of 61's that I had never seen before so I added them for everyone as well.

samparfitt

My Feedback: (43)

Kram,
thanks for all the encouragement.
I always welcome comments: there are many ways to get the same job done.
Each of us have different talents so no matter what procedure works better for each of us, we all end up with the the same product.

David,
Thanks for posting the pictures.
Amazing that P-61 made it home with that much damage.
It must be nice to be able to make your own mufflers.

=========================
Gear Doors.

I'll be using the wooden gear doors cut from the booms but I want a 'back up' pair of FG doors in case the wooden doors don't 'work out', or for future repairs.
The gear doors use most of the blisters and the rest of the blister is on the boom but I figured that a FG copy of the entire area is best if the doors need to be replaced.

pic 1:
I taped off the gear door area to keep the FG and resin restricted to a confined area.
I brushed on one layer of evercoat mold release agent onto the boom surface and will apply one more coat after this dries. The mold release seems to be drying slowly so I brought them upstairs out of the basement to get them to dry faster. Being winter and low atmosphere moisture, I figured, wrong, that they would dry fast. I was going to use monokote for protecting the booms from the resin but I was thinking that I wouldn't be able to conform the monokote very well around that blister.

samparfitt

My Feedback: (43)

Gear doors (cont)

pic 1/2:
For the first layer of cloth, I used 1 oz cloth and I applied a liberal amount of finishing resin using an acid brush to the FG cloth. Unlike glassing the plane, I leave the resin thick on the cloth.

samparfitt

My Feedback: (43)

Gear doors (cont)

pic 1/2:
After the resin was fully hard (about 3 hours), I next applied 2 oz FG cloth with finishing resin.
The 2 oz cloth fits snugly around the blister so no cutting was needed.
I worked from the center out applying a liberal amount of resin.
I'm also glad that I added that extra ply behind the former just behind the gear doors as one side is only 3" wide and the other side is only 4" wide. Some CF would probably also have worked.

samparfitt

My Feedback: (43)

Main Gear doors (cont)

After one layer of 1 oz and two layers of 2 oz FG cloth, I removed the FG doors.
I had some trouble removing them as the resin lightly stuck to the booms.
The FG doors pulled some of the FG cloth from the booms ( I just put some resin on those spots and layed some cloth over it).
The evercoat mold release has always worked on canopies.
I'm guessing that the molding release never completely covered the FG cloth on the booms since the surface was not sealed. If I would have had a coat of primer on the booms, this problem probably wouldn't have happened.
I labeled each FG gear set for future reference, should they be used.
Next, I cut out the main gear doors.
Again, I used some straight pins to locate the corners of the doors. I then used a razor saw plus a razor saw with no stiffener on the back side so I could cut vertically to the surface. The doors were also labeled as to which boom and also left and right door.
I had to trim the spruce stringers along the wooden mounts to fit the gears to the mounts.
There's not much room on the back area of the boom to put a hinge there: I'm going to have to 'sleep' on this one to get that hinge to fit.

pic 1:
FG gear doors.

pic 2:
some of the booms FG cloth got ripped off.

pic 3/4:
I labeled each set of doors and used pins to locate the corners and cut with razor saws.

pic 5:
With only 3" and 4" of boom just aft of the gear doors, I'm glad that I added that extra sheer ply.

pic 6-8:
Stringer had to be trimmed so the gears would fit on the mounts.

pic 9:
About a 1/4" deep cut was made on the ply spar to make room for the air cylinder.
I cut two holes in case I ever need to add an extra air cylinder.

samparfitt

My Feedback: (43)

On her legs!

simple

My Feedback: (9)

Congrats Sam!!!

Looks like you needed a larger room to do the first full test assemble - LOL!!!

Amazing build, I think the big book said, (And on the 7th day he rested

Awesome!!!

at-6 texan

Great Sam. Would you be so kind as to explain the procedure to make the bubbles on the doors to the widow gears...thk.

All Day Dan

My Feedback: (5)

Excellent. Dan.