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chuck540z3

1/32 P-38L "Kicked Up A Notch". Jan 15/16: FINISHED!

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This is the exact reason I ask the question.  Sometimes we modelers do what somebody else does, but we really don't know why.  Like I said, I can easily add a bit of reinforcement, but that can cause other problems, like the dihedral of the wings could change (including side to side), the fit to the lower fuselage could be altered forcing the boom alignment (and resultant wheel alignment) to be wrong and other things that might make me regret my decision.  Now if there was/is a real reason to do this, I'd like to hear why so that I can make modifications accordingly, which might mean another approach to the problem.  I've heard that the wing to boom fit is poor and there is stress at the join that sometimes cracks.  If so, reinforcement of the entire wing is unnecessary.  If you know anything about this problem, I'd sure like to hear about it!

 

Thanks Guys!

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Chuck,

I have been following your build with much interest as I have one on the shelf of doom awaiting a restart.  I am at about the same point in construction as you.   I have had two concerns.  First would be alignment of the booms and horizontal tail, caused by my second concern which would be distortion from twisting stress.  My gut tells me that once properly aligned with jigs etc, and glued with liquid cement or epoxy(not CA), the whole assembly will be rigid.  Especially if not handled roughly during final assembly and painting.  But I might err on the side of caution.  After assembly, I am more concerned with busting joints than alignment.  Not having interlocked spars and frame like the real plane, might cause the model to be a little flexible.  I have taped mine together several times, an no matter how rigidly I tape it together, it still seems to have a little too much flex for my taste.

 

I have considered stiffening the wing simply to prevent twisting, as that seems to be where the twisting originates.  The booms don't really flex.  The wings, being broad and flat, make for easy twist.  However, wing tip to wingtip (spar)strength, should not be an issue.

 

Hope that helps

 

James B

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Thank you very much James for this input!  What you have told me has convinced me that I should do the same- ie: tape the whole thing together before I commit.  This will not only help me, but I will document what the issues really are and, hopefully, what an easy solution will be.

 

Cheers,

 

Chuck

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Hi Chuck!

 

I feel that the plastic is fairly soft in this kit and could lead to problems a few years down the road. Couldn't hurt to give yourself a bit more rigidity.

 

John Clements

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Chuck,

I like alberto49's idea of the flat spar behind the cockpit as well as adding plates in the wing between the cockpit and booms. Shape some plywood to fit snuggly on all four sides, into the lower half of the inner wings. Attach with epoxy or epoxy putty all around. Combining these two should do the trick. Solid glue joints when assembling the major components is a must also. No CA!

 

Paul Budzik has an article on his website about making a p-38 jig.

http://paulbudzik.com/tools-techniques/P-38%20Alignment/academy_p-38_alignment.html

 

Happy modeling buddy!

 

James B

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Chuck,

By the way... I have learned a lot from your build threads, and a few others here on LSP. So much so that I have been inspired to start a thread myself. I am building a Revell 1/32 He-162. Haven't done much lately because of work, but will continue to post as I progress.

 

I am a big fan of showing not only your work, but explaining it in detail as you go. I believe plastic modeling is loosing steam here in America and slowly dying. Forums like this, where people can learn, and advance their skills with good mentoring from guys like you(and me) will help keep fledglings interested. It may also inspire new people to buy their first model, knowing they have a place to go for advice.

 

My wife put me in contact resently with a young man (18 year old and going off to college) in her web game group that has just gotten into models and loves it. Unfortunately his dad knows nothing of models but is supportive of his son's new hobby. Via emails, I have taken him under my wing and we are working on basic skills, and I am explaining various things about, paint, glues, sanding etc. I have also provided him with links to my favorite forums and builds. A copule of yours were in there.

 

So keep up the good work! I appreciate you sharing your experience with me and the rest of the group. I hope anything you learn from me may be at least half as valuable as what I have learned from you.

 

James B

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Chuck,

By the way... I have learned a lot from your build threads, and a few others here on LSP. So much so that I have been inspired to start a thread myself. I am building a Revell 1/32 He-162. Haven't done much lately because of work, but will continue to post as I progress.

 

I am a big fan of showing not only your work, but explaining it in detail as you go. I believe plastic modeling is loosing steam here in America and slowly dying. Forums like this, where people can learn, and advance their skills with good mentoring from guys like you(and me) will help keep fledglings interested. It may also inspire new people to buy their first model, knowing they have a place to go for advice.

 

My wife put me in contact recently with a young man (18 year old and going off to college) in her web game group that has just gotten into models and loves it. Unfortunately his dad knows nothing of models but is supportive of his son's new hobby. Via emails, I have taken him under my wing and we are working on basic skills, and I am explaining various things about, paint, glues, sanding etc. I have also provided him with links to my favorite forums and builds. A couple of yours were in there.

 

So keep up the good work! I appreciate you sharing your experience with me and the rest of the group. I hope anything you learn from me may be at least half as valuable as what I have learned from you.

 

James B

 

 

Thank you very much James.  Glad I could help!

 

 

Well boys, I took James' advice and dry fit the wings and booms together to see what the problem might be and how to fix it.  NOW I know why modelers reinforce the wings!  It's not a strength thing as much as a dihedral error if you don't, which also causes wheel alignment issues with the booms.  Here's a pic of the right wing from the front.  Note the alignment issues of the wing and landing gear.  BTW, I have good reference drawings of the front of the P-38, which shows that the inner wing and outer wing are roughly on the same plane, not bent at the booms.

 

 

Dihedral1.jpg

 

 

On the right wing, there is a nasty gap on the inner side of the boom....

 

 

 

Dihedral2.jpg

 

 

 

On the left wing, much the same.

 

 

Dihedral3.jpg

 

 

But this time the big gap is on the outboard side of the boom.

 

 

 

Dihedral4.jpg

 

 

 

The fit on top is really quite good, so no issues there.

 

 

 

Dihedral5.jpg

 

 

 

So, here's the plan, much like what some of you guys have done already:

 

1)  Reinforce the upper wing to "pin" the dihedral correctly

 

2)  After gluing on the lower wings, glue the booms into place, BUT make sure the wheel alignment is also correct on each side

 

3)  Repair the gaps as required, which should be even bigger on both sides of the boom than the pics above

 

 

BTW, why the suggestion to NOT use CA glue?  I have a theory, but I want to make sure.

 

Thanks guys!

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CA does not make a good joint when expose to twisting and bending. CA works best on joints that would be pulled directly apart. Think of the guy in the crazy glue commercials hanging by a drop. Strong joint while gravity pulls him straigh down. But if was to start bending his head side to side, torque load would break the joint. Some people glue fuselage halves together with CA. Very strong and fills gaps. But if you were to twist that fuselage just a little, joints could break. I am sure you have had some similar experience.

 

I am rough with my models as I build, so I avoid CA for anything but gap filling, PE parts, and tiny details. Plastic to plastic is always liquid cement first, epoxy next, CA last. Major joints never get CA. Liquid cement makes the best joint as it welds two peices into one. Epoxy is strong, but you have to prep the mating surfaces to provide "grab", you have to mix epoxy, it's messy, and you waste alot by usually mixing more than you use. You can thin epoxy with alcohol to make it more brushable, and you can clean away excess with alcohol also, before it cures of course. 30 minute epoxy gives you work time also to get the joint just right. It takes a day or two for epoxy to fully cure, but then it is indestructable. I even use epoxy before CA on PE and tiny bits unless unavoidable.

 

I do use CA sometimes in combination with epoxy and liquid cement though. When using a slower curing adhesive, leave a little dry spot for a tiny spot of CA. Gluing a horizontal tail as an example. Brush 90% of the mating surface with epoxy, and the rest with CA just before mating(or tack with tiny spot of CA, then use liquid cement). The CA cures quickly, acting like a clamp to hold the tail in place in alignment. However, the epoxy(or liquid cement) provides all the strenght when cured. I use this technique all the time when building balsa planes. However, I use wood glue in place of epoxy.

 

James B

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By the way, you are right, the p-38 wing should be straight all the way out. No change at all in dihedral from centerline to wing tip. And wing thickness tapers evenly from centerline, through the booms, on out to just before the end of the wing. There, you will see that the bottoms of the wing tapers up to meet the top of the wing. Just the last two feet or so.

 

James B

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Now I remember why Russ put his reinforcing spars : for the same reason sa shown on your pics, Chuck. I should have been less lazy and gone back to his thread on the P-38 :BANGHEAD2:

 

HUbert

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Great detective work Chuck.  I did the same with my 24th Mossie, not for strength but to correct the dihedral which was also too flat. Bonus was it also made for a rigid wing structure at the same time

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Just for info, the only picture I have of my P.38 where the dihedral can be appreciated, shows that the reinforcement did the job:

 

DSCN0591-vi.jpg

 

I also confirm that I used epoxy glue to bond that reinforcement to the wings; CA just helped to position everything in the right place.

Alberto

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July 7, 2015


As modelers we sometimes wish we had done certain things ahead of time, because installing or changing parts later can be very difficult, if not impossible without making a mess.   This is the case with the navigation lights, which are tiny bits of clear plastic that are supposed to fit in small holes in the wings and rear vertical stabilizers.  The kit parts have a hole for these lights alright (Parts # K-12), but they have a large raised lip around where the light is supposed to go and the hole isn't nearly big enough.  This thin lip is way too big for scale and if you can't see it from 16 feet away on the real deal, you shouldn't be able to see it from 6 inches away at 1/32 scale either.

The solution for both problems is to sand the lip off completely and carefully widen the hole, BEFORE the wing halves are glued together.  Here's a pic of the lower wing halves, with the unaltered port side on the right and the corrected starboard wing with navigation light dry fitted on the left.  This pic also shows the tiny lights on the very thick clear sprue at the top.  Getting these lights off the sprue cleanly without losing one or two is VERY difficult!



Navlights1.jpg



Here's a pic of the upper starboard wing tip, unaltered.  There's no way in heck that light will fit in there.



Navlights2.jpg




With lip sanded off and hole widened with a #11 knife tip and thin round file, the light fit is much better and will now be a “drop in†at the end of the build.



Navlights3.jpg



Now I wish I had done the same thing to the vertical stabilizers before gluing them together, but if you sand and trim the hole carefully, you get the same effect.



Navlights4.jpg



Now back to those crooked wings, which sag at the booms.  As many other modelers have done on this kit, I reinforced the wings with a brace.  Some have used metal parts and others styrene, but I thought the perfect solution might be ordinary plastic chopsticks.  The chopsticks I used are light and flat on one side, but they are quite strong and are flexible.  They were easily cut and sanded down at the tips to fit, much like ordinary resin parts.

To glue them to the upper wings, I didn't use CA glue, because it might crack under flexing stress (thanks James B. for the tip!) and I didn't use epoxy glue either.  I used ordinary “GOOP†for household use, which is a very strong but still flexible adhesive and sealer that is clear.  It takes longer than epoxy cement to dry and cure (up to 72 hours), but the results are exactly what I need.  GOOP “sticks like snot to an oven doorâ€, so these chopsticks aren't going anywhere and the wings will be allowed to flex a bit when I install the booms.  Note that I sprayed the chopsticks black underneath the superchargers, so that they can't be seen later from the top through the thin gaps on either side of the supercharger.



Chopsticks1.jpg


Another view from the front, where the dihedral of the wing now looks straight and correct:


AFTER:


Chopsticks3.jpg



BEFORE:


Dihedral3.jpg



The dry fit of the wings earlier gave me my first opportunity to calculate how much lead I will need in the engines and the nose to keep this bird from being a tail sitter.  The answer is, a LOT, so I can't think of anything better to glue the lead pieces securely than more GOOP.  I squeezed some of it into the engines, which I left open at the top, then placed the lead pieces on top, followed by more GOOP to create a solid mass that won't ever move.



Goop1.jpg



You may have noticed in the above pics that I already installed the Masterdetails resin superchargers into the upper wing.  Although there are no instructions for these parts, they fit nice and snug from underneath, but are a very hard to install from above, as with the kit parts.  Further, they can be glued from underneath so that you don't see any glue marks.  Also recall that I painted the sides of around the superchargers black earlier, which would also be scratched if the superchargers were installed from the top.

Before painting the superchargers, I checked many, many reference pics.  Wartime superchargers are generally quite rough looking with lots of rust and staining, while brand new ones are almost entirely clean steel.  My hanger queen subject has them painted flat black to the rear collar, then a combination of steel and black.  I left mine all steel at the rear, because I wanted to show off the fine features of the Masterdetails resin- and I just like it that way!



Supercharger5.jpg



Next up, the wing halves get glued together along with the flaps and ailerons, followed by the lower fuselage in the middle.  The booms will go on last, which I already know will give me fits as I strive to keep the landing gear straight.  I HATE kits where the landing gear must be installed early!  The painted parts scratch during construction and you can't alter the gear alignment without a struggle.  We'll see.

Thanks for checking in.

Chuck

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hi

 

great job ( as usual) ...Now , you know why this reinforcements are needed ......I too hate these gears glued early , it's so easy to break them during the build , that  happened to mine ....

Alain

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