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1/18 Scale Blue Box F4U-1A Corsair Modification


JayW

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Here is a better picture of the R-2800 engine cases, with the area between the red lines being what I have modeled so far with this lathe turned and milled piece:

 

k3k6cu1l.jpg

 

In order to do hole drilling, I had to create a jig of sorts to better assure the holes are in the right place, and perpendicular to the faces where they are being drilled.  Very important"

 

uG7EOaJl.jpg

 

And here is the completely finished machining.  Compare to the upper photo of the real thing:

 

pnTiOrIl.jpg

 

I can tell you I am a happy camper with that part.  You think those big 3/16 dia machine drilled holes were not a bit nerve wracking?  After hours and hours of machining?  Cannot wait to crown it with 9 cylinders, valve pushrod tubes,  and intake manifolds!

 

 

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  • 3 weeks later...

And, the cylinder heads are finished a few days ahead of schedule:

 

xUFkuotl.jpg

 

Big milestone.  You can be assured, if you were not, that I am fully invested in this engine project, after all that monotonous toil.  Next on the docket is to take a couple days off.  I have been somewhat of an obsessive the last few weeks.  When i am ready to go at it again, I think I will treat myself to something with a bit more immediate gratification, which will be the forward half of the crank case.  Recall I have done the aft half already.  Here is a shot of it painted up and with Meng nuts:

 

H7YgmMEl.jpg

 

The goal of course is to make the crank case look like this (found it on E-bay):

 

MvqEHJwl.png

 

I will post when that part is done.  Then, some more tedium while I make the lower cylinder bodies (have already done one as you can see in the first photo).  At the same time I will add air deflector jackets like these:

 

 gT3tEqIl.jpg

 

I look forward to making a set front and rear - not so much the other eight sets!  I know this is not very exciting but stick with me.  Once I get the cylinders done, it's going to be one cool thing after another.  Thanks! 

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The front half of the crank case has been machined from acrylic, and detailed.  It was not as hard as the aft half, because the aft half had the intake manifold ports.  Here:

 

 f4uv0lHl.jpg

 

Combine this piece with the aft half and it begins to look like a crank case:

 

qnXf8Osl.jpg

 

It is now time to sprout its blossoms (the cylinders).

 

During my days off, I could not stop the little gray cells cogitating the problems ahead, which are many.   Some involve the curved and formed pipes that make up the intake manifolds, and the exhaust pipes.  So I attempted a little tuffy - the P & W provided exhaust stack for the forward row of cylinders - this part:

 

 3Zwqkljl.jpg

 

Note it is actually a tube within a tube perhaps with the outer tube as an insulator of sorts (?).  The outer tube has a weld fin along its length, and a flange near where it attaches to the cylinder head.  And it is the "S" shape that makes it so challenging.

 

I am going to use .125 inch diameter solder to make all these parts.  This stuff:

 

 9G0LzqRl.jpg

 

Now - the main reason I am using solder is because it can be formed relatively easily.  I say relatively.  This stuff is pretty stiff, taking alot of force to bend it.  But once formed or bent, it has no springback, and unlike a tube, it has no thin walls that can collapse during extreme forming.  I used .117 inch diameter on the Thunderbolt a couple years ago - that stuff was easily found in hardware stores.  The .125 inch stuff was harder to find, and more expensive. It is also the largest diameter I could find commercially, and it actually is not large enough.  For instance, a typical exhaust pipe on the Corsair, per drawing, is 2 11/16 inch diameter, or .149 inch in 1/18 scale.  Although I cannot find similar data on the intake manifold pipes, by scaling various engine related drawings for Corsair and Thunderbolt, the diameter appears to be about the same as the exhaust pipes.   Well - I have to use the 1/8 inch stuff; I have no choice unless any of you have any bright ideas.

 

So - for that little exhaust stack prototype, I created a robust fixture, or tool, and it has to be robust:

 

2i5QpIRl.jpg

 

This fixture assures a fairly exact and repeatable final shape of the part.  The solder was first lined with .156 diameter plastic tube, reamed to .125 inch ID, because it has to be slightly larger diameter than the rest of the exhaust piping.  And then forced into an "S" shape with the fixture. It took a couple of tries with modifications made to the fixture.  But it seems to work OK.  I was fairly amazed the plastic didn't just split apart - it did not want to be formed into that shape!  I now hope the fixture is robust enough to do this 8 more times.

 

Here is the finished prototype part, which I think is good enough to just use as is:

 

mfT7EOjl.jpg

 

OK - must keep my eye on the ball.  It is now time to finish the cylinders, including the air deflector jackets.  That is what you will see next post.  Thanks.

 

 

 

 

 

Edited by JayW
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  • 3 weeks later...

I wanted to get four cylinders complete and then post.  But I think I am going have to leave the modeling for a couple weeks to address a Corona Virus risk, the details of which I will not bore you with.   Except to say we have a family member who needs to be quarantined and I and a very old mother in law need to be away from this person for the incubation period at least.  In so doing, I will be away from the man cave where my modeling happens.  Should be OK - just a near term PITA.

 

Now - work has been humming along on the cylinders.  Let me show you. 

 

    rKbk967l.jpg

 

you see a major piece of tooling - a check fixture of sorts that assures exact positioning of each aft cylinder (I have a different one for the front row).  And importantly it assures exact positioning of the intake and exhaust stacks coming from the back of the front cylinders.  Note the pairs of protruding silver tubes.  The white cylinder is not fully prepared (the fourth one I had hoped to finish for you).  The other three are complete.  More pictures:

 

UuSsKm7l.jpg

 

Included you see the valve guide tubes and tappets and the exhaust and intake stacks.  Note how they joggle in towards one another, and squeeze through between the aft row cylinders.  The lower pipe will connect to the intake manifold.  The upper one will connect to the exhaust manifold.  One day you will see these impressive details.

 

kRoZNeal.jpg

 

Also included are the air deflector jackets that you see attached to the sides of the cylinders.  

 

That's all for now.  Hopefully you can see how this is being assembled.  Much of my time has been spent fabricating these fixtures, and I am not done.  Once completed though, I can get repeatability for all the other cylinders coming down the pike.  

 

Take care, stay healthy, exercise social distancing, and I will post soon as I can.

 

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  • 1 month later...

Let's see - it's been a month.  The world has changed.  I hope you are all well and have stayed clear of the virus.  I gotta say - were it not for my shelter-at-home status I would not have made this much progress.  Recall I am in cylinder mode.  I decided to go finish off the front row before the back row - it was a marathon.  Here is a shot of the front row in process, with my handy dandy cylinder location fixture:

 

 7S0scW2l.jpg

 

The little pegs are designed to insert into the exhaust and intake ports in the back of the cylinder heads.  You may ask why I need a locating fixture if I have holes in the engine block and metal rods in the cylinders.  Well, the holes in the engine block are not particularly accurately located.  The exhaust and intake pipes that will protrude from the rear of the front row cylinders have extremely tight clearances with the aft row cylinders.  So I need tight controls on cylinder location, and I felt tooling up the exhaust and intake ports would be the best way to do it.  The rods in the cylinders are smaller diameter than the holes in the engine block, so there was room to slide the cylinders around a bit.  We'll see.

 

And finally - all nine front row cylinders are finished and mounted onto the engine block:

 

uyvkVnfl.jpg

 

What a milestone.  That was labor intensive.  The backside looks like this:

 

v9lmgVWl.jpg?1

 

My first R-2800 for the Thunderbolt had exhaust and intake port holes drilled as an afterthought.  Looked positively awful until all the pipes covered everything up.  This time - the ports are designed in very similar to the real thing.

 

Next is a break.  I need it.  Then the aft row of cylinders and the exhaust and intake stacks.  Should take about a month and some.  Once done she is going to look a whole lot like a R-2800.  Thank you for your patience, and stay well!

 

 

Edited by JayW
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Wow Jay! I've missed much of your recent progress (I think due to being consumed in my own work!) but that engine is an absolute Jewel! I'm incredibly impressed at how you are able to make not just one, but 18 whole cylinders from scratch and have them all look the same! Your jigs to assist with fabrication are really well though out too. I doubt there is anyone else out there who would take on something like this and succeed as you have. Can't wait to see more!

 

Cheers,

 

Craig

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