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RE: Yellow P-38 build thread - 8/1/2007 11:36:17 AM   
Doolittleraider



Posts: 364
Joined: 11/1/2003
From: lakemary, FL, USA
Status: offline 		Wow. I am soory to hear that.Thats frustrating I know I would rather crash a plane then lose it like that. We all know that at the rate you build you can replace a loss like that in just a few weeks....tops! I Have had my Yellow p-40 for almost two weeks and I just finished the flaps last night. I am looking it having it done by march.

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"No Mission is routine."
www.doolittletokyoraiders.com

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       Post #: 26

RE: Yellow P-38 build thread - 8/1/2007 7:07:58 PM   
samparfitt


 

Posts: 1866
Joined: 9/1/2002
From: West Chester, OH, USA
Status: offline 		Counter weights:

pic 1:
I cut the counter weights in half and epoxied in some 4/40 steel rod.

pic 2:
Holes drilled into the elevator and the counter weights dry fitted in the holes.
Will epoxy after all the wet sanding is done.

----------
elevator (cont)

pic 3:
Four large Robart pin hinges epoxied in the elevator.
Note: I made a 1/4" ply (with hole) that will support the outer ends of the control horn rod.

pic 4/5:
Elevator epoxied into the horizontal stab and the control horn rod supports also epoxied in.
The bottoms of the booms were trimmed away to allow access to put the elevator in.
A tight fit and it almost takes three hands to get the elevator attached to the stab.

pic 6:
one inch up elevator (plans call for 3/4" ).
Only about a 1/2" down elevator (there's no way I'm ever going to do outside loops with this plane so 1/2" is plenty!).
I epoxied to the stab in the up position to insure I had sufficient room since the stab has about a 1/4" overlay on the top & bottom to meet the LE of the elevator.

pic 7/8:
Elevator control rods made from 4/40 rod, carbon fiber tubes and 1/4" wood dowels.
I drilled a hole down the middle of the dowel and cone shaped one end and also drilled a hole on the side of the CF tube for the bend of the 4/40 rod to stick 'out of'.
Epoxied slopped on, the bent end of the rod put into the hole in the side of the CF tube and then the dowel pushed into the CF tube.

pic 9:
4/40 rod screwed to the elevator control horn.

pic 10:
the other end will be connected later.






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< Message edited by samparfitt -- 8/1/2007 8:09:34 PM >

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G. Samuel Parfitt

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       Post #: 27

RE: Yellow P-38 build thread - 8/1/2007 7:21:29 PM   
samparfitt


 

Posts: 1866
Joined: 9/1/2002
From: West Chester, OH, USA
Status: offline 		Inner Flaps access panel.
There's not a lot of room in there so I decided to cut an access hatch.

pic 1:
The pencil outline of where I will cut the access hatch to put in the servo for the inner flaps.

pic 2/3:
A dremel cut off disk made quick work of the hole.

-----------------------
Rudders (continued).

pic 4/5:
Rudder parts.

pic 6:
Inside view of upper balsa hinge support epoxied into the rudder.
Not much room in there so I drilled a hole where the bottom of the balsa support is suppose to end so I could look in the hole and just push the balsa support until I saw the balsa support through the hole.

pic 7:
Inside view of bottom balsa hinge support exoxied into the rudder.
Note that this balsa hinge support also gets the rudder control horn so there is a 1/8" ply also CA'ed to the side of the balsa block.
Since the control horns go on the inside of the booms, I made sure the ply is on the inside of each rudder and then scratched in a mark so I can tell later 'which is which'.

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G. Samuel Parfitt

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       Post #: 28

RE: Yellow P-38 build thread - 8/2/2007 12:31:04 AM   
samparfitt


 

Posts: 1866
Joined: 9/1/2002
From: West Chester, OH, USA
Status: offline 		Elevator/rudder servos.
All views are with the plane on it's back and from the front.

pic 1:
Installed four HS-645 (133 oz for 6 volts) for the elevator and rudder (two each).
This is the right boom: elevator on the left side and rudder on the right side.

pic 2:
This is the left boom: elevator on the left side and rudder on the right side (mounted horizontally).
With the elevator servos both on the left I get the exact same movement (theoretically!) to each side of the elevator.
At least it is when I move the elevator transmiter stick: no binding.
I did this so no 'reversers' are needed.
I connected up the elevator to the servos because, once I put the vertical stabs on, you can't get to the elevator control rod and horn.
I mounted the left rudder servo horizontally, again, to remove the need for 'reversers'.
I used some 'L' brackets to rotate the servo 90 degrees.
Yellow and Bob Violet sells these.

Pic 3:
Elevator in the full up position.

pic 4:
Elevator in the full down position.
(both of these throws will be dramatically reduced for flying).

pic 5:
I used Debro's 4-40 swivel ball links (#861)
I used 3/4" servo arm distance (center screw to ball link) on the elevator and 7/8" servo arm distance on the rudder.

pic 6:
No time like the present to start routing the wires to where they will actually be located.
The receiver will be in the front of the center fuse.

pic 7:
It's a mess already and I've only done elevator and rudder!
The elevator used one 'Y', two 12" and one 18" extensions (as did the set of rudders).
I used HD twisted extensions from air wild: they have some very good prices on HD twisted wires.
(www.airwildpilotshop.com)



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< Message edited by samparfitt -- 8/2/2007 12:47:43 AM >

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G. Samuel Parfitt

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       Post #: 29

RE: Yellow P-38 build thread - 8/2/2007 1:33:50 AM   
orvel



Posts: 254
Joined: 6/7/2002
From: Allentown, PA, USA
Status: offline 		Samparfitt, first of all, great job, man you work fast! Second, your Yellow P-38 has a polyester based fiberglass fuse, what are you using as an adhesive to glue the wood parts to the fuse? When I built my Yellow jug, I used polyester based Bondo mix.

< Message edited by orvel -- 8/2/2007 1:35:33 AM >

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       Post #: 30

RE: Yellow P-38 build thread - 8/2/2007 2:09:07 AM   
samparfitt


 

Posts: 1866
Joined: 9/1/2002
From: West Chester, OH, USA
Status: offline 		Orvel,
Are you saying that the epoxy may not stick to the FG?
I just got some Zapa dap a goo II that the instructions also recomments!

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G. Samuel Parfitt

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       Post #: 31

RE: Yellow P-38 build thread - 8/2/2007 3:02:36 AM   
t_burley



Posts: 2616
Joined: 1/11/2002
From: Bakersfield, CA, USA
Status: offline 		Sam, as is the usual, I enjoy watching your build threads. I know from building
myself, it takes alot of work, to work out all the details. then add in all the pics
you do, the steps taken to post it all, and being organized with it makes it even
more work! . nice work, look forward to seeing it all come together

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Todd
Meister, Aero Acc., Sierra, Glennis, Get Stencils, Shinden, Warbird Colors, Fliteskin customer

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       Post #: 32

RE: Yellow P-38 build thread - 8/2/2007 4:31:05 AM   
orvel



Posts: 254
Joined: 6/7/2002
From: Allentown, PA, USA
Status: offline 		Sam, that's precisely what I'm saying! Yellow fuses are made of polyester fiberglass, regular epoxy although it will appear to hold initially, will not hold over time. That's why in their instructions (at least on my P-47 which I bought 5 years ago) they recommend a product called "Stabilit" (which they sell) for gluing wood to their FG. I personally used Bondo "Ultimate Lightweight Body Filler" which is polyester based and it works very well. You might want to check this out, you don't want to have what I'm sure is going to be a beautiful P-38 fall apart on you in flight!

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       Post #: 33

RE: Yellow P-38 build thread - 8/2/2007 4:37:51 AM   
samparfitt


 

Posts: 1866
Joined: 9/1/2002
From: West Chester, OH, USA
Status: offline 		Todd,
Taking pictures, downloading them and writing this thread probably eats up 1-2 hrs a day...but it's worth it.
It helps me stay focused, be more organised and think things through for the best options.
It also helps me learn new approaches from other builder's input.
An example is the polyester (green) FG that the P-38 is made from.
Pic 1 shows the glue that I think that Yellow recommends for FG to FG.
I was going to use this on the vertical fins to fuse.
A reference was made that regular epoxy may not be the best for this type of FG.
I'd appreciate any input on this.

--------------
Tank trays (cont)

pic 2:
I used 4/40 blind nuts on the tank tray.

pic 3:
Tank tray screwed in using 4/40 hex head bolts into the blind nuts.

--------------
pic 4.
Some #6 blind nuts added to the stearing servo tray.

pic 5:
The stearing servo tray mounted using hex head bolts.
Since yellow recommends a heavy duty servo (I used HS-645), I used 4/40 rod and those same ball sockets as on the elevator/rudders.
Without that access door on the nose, mounting this servo would be very difficult.




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G. Samuel Parfitt

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       Post #: 34

RE: Yellow P-38 build thread - 8/2/2007 5:03:15 AM   
samparfitt


 

Posts: 1866
Joined: 9/1/2002
From: West Chester, OH, USA
Status: offline 		Orvel,
My instructions have stablit also at the beginning but in the building process, they say use Zap-a-dap-a goo which appears to be what I have purchased. The instructions seem to be inconsistent: Use Zap-a-dap-a for hinge dowels glued to the elevator but suggest using 30 minute epoxy to glue the vertical stabs to the rudder post. I'm assuming yellow thinks the elevator will get more stress than the vertical stabs.
My main concern is high stress points like the servo mounts on the inside of the fuse wall.
Yellow recommends to also glass them to the fuse.
I can used the Zap-a-dap-a to additionally secure those.


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G. Samuel Parfitt

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       Post #: 35

RE: Yellow P-38 build thread - 8/2/2007 5:22:22 AM   
kram



Posts: 484
Joined: 7/11/2002
From: ames, IA, USA
Status: offline 		Sam! You shame us all with your speed and sophistication!

Just watching one of your building threads makes me want to build another one.

Six years ago, I too struggled with the choice of epoxies. I bought some of their Stabilit, but found it difficult to work with and not that strong when cured. Eventually I settled on the slow epoxy Nelson Hobbies sells (System Three?), but of course made sure I sanded the finish off all FG parts I glued. It looks like Yellow glues their ply formers to the polyester glass with some kind of hot glue, but those glue joints aren't the greatest...they seem to rely more on fit and internal pressure to hold together.

So I cheated a little on some critical areas to get more structural integrity, like on those servo platforms for the rudders and elevator........I carved out a plywood plate that ran all the way across the boom and held both servos....giving it a lot more solid feel pressing against both sides of the boom rather than clinging precariously to each side like a cliffside swallow's nest! This required carefully cutting out enough of the plywood for the wheels to retract, but worth it for two such critical control surfaces. I'll try to dig my Yellow out of mothballs and post a picture, if you like.

You're gonna love this plane and I'm sure yours will be a lot prettier than mine, which served as kinda my "Workhorse 38" for four seasons.

mt

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       Post #: 36

RE: Yellow P-38 build thread - 8/2/2007 5:36:11 AM   
kram



Posts: 484
Joined: 7/11/2002
From: ames, IA, USA
Status: offline 		Sam:

There is a right and a left rudder, identify by the little molded tail light on the outside of each. Yellow actually sent me two lefts, but I never corrected it....wasn't that scale-detailed a plane for me.

There is also a subtle difference between right and left cowls (other than the R and the L markings!). I just can't remember what it is.

There will be A LOT more stress to the glue joints in the rudders and the vertical stabs than those hinge dowels for the elevator. As my Yellow got older, I actually re-did the wood in the rudders and vertical stabs and reinforced them with tiny little button head screws.


mt

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