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

[JayW]

All R-2800's are attached to the airplane via a truss supported ring, and six vibration absorbing "Lord" mounts.  The Corsair is no exception.  Here is the Vought/Sikorsky drawing of the engine mount for the F4U-1 and 1A:

 

 

I have made the ring; the truss behind it will come later, maybe much later.  And that only if all continues to go well with my plan to have an openable engine compartment aft of the cowl flaps.  That is not certain at this point.  You may notice in the picture above that there are six mounting points on the ring - four above the horizontal centerline, and two below.  That is where the "Lord" mounts attach.  The Lord mounts look like this:

 

 

Item number 1 above, I believe, is the hard rubber insert for vibration damping.  I had to deal with these mounts on the Thunderbolt engine as well, but the six I have made for the Corsair are a little better, as I think they will be a bit more visible (you cannot even see them on my Thunderbolt).  Here is a shot of the mount ring, and the partially assembled Lord mounts:

 

 

You only see five Lord mounts - the sixth one is already on the engine.  They are made from simple plastic shapes, plus some Meng nuts.  The ring itself is made from that .125 inch diameter silver solder I used for the intake and exhaust manifolds.  I created a fairly simple fixture to assure a circular shape of the right diameter, and to properly locate the pads for teh Lord mounts.

 

The Lord mounts attach to the engine in between the intake manifolds, like this:

 

 

 

And with the ring test fitted:

 

 

Tell the truth, I was not very happy with this installation.  I thought I had closely positioned the Lord mount pads on the ring, but with the fittings properly located on the engine, they really didn't align that well with the pads.  But the viewer is going to be hard pressed to see that once the engine compartment is complete with an astounding amount of clap trap in there competing for attention, including the exhaust stacks that cover them up quite a bit.  

 

Next I believe is going to be cowl stuff, including cowl flaps.  The Corsair cowl flaps are an incredible rube-goldberg cable actuated contraption.  At the moment, of course, I don't have a good plan.  It's either going to be that, or the supercharger section of the engine which will involve the lathe.

 

Take care.

 

 

Edited August 14, 2020 by JayW

[JayW]

I decided to do the back sections of the engine at this time.  I am not sure I have seen anyone model these details, because they are normally hidden.  Not so for this model (I hope) - as the engine accessory compartment is going to be openable if I can pull it off.  

 

Boy, there are untold variations of the R-2800 even if you ignore the modernized "C" versions.  The Corsair had a "B" version which looks very similar to the "A" version which was the original.  R-2800's had a single stage two speed supercharger as standard.  I think most R-2800 equipped aircraft had this.  The Thunderbolt for example had that kind, but it also had a separate turbocharger that fed compressed air into the R-2800 supercharger.  These engines have a kind of stubby aft section.  The Corsair (and Hellcat) had two-stage superchargers which were contained in the engine.  These engines were characterized by longer back ends with an extra section for that second stage.  Here is what the Corsair engine looks like:

 

   

 

Bad to the bone.  Check out all that stuff aft of the cylinder banks.  That is my challenge.  Note the carburetor on the bottom behind the cylinders.  It attaches to the auxiliary blower section, which is that extra section I was talking about, and what this post is about.  Here is a picture of it from one of the R-2800 part catalogs (complements of AirCorps Library):

 

 

My plan was to create a basic lathe turned part, and carve it up with the end mill to accept a number of plastic inserts for mounting surfaces.  Also the aft flange would be a separate part made from plastic sheet. 

 

Here is the lathe turning:

 

 

Three flat surfaces must be provided on this part (also the sides are flat) - one on the bottom for the carburetor, and two on top for the air intake ducts.  Here it is with slots milled in, and plastic inserts added:

 

 

You also see Meng nuts, and to the right the very ugly diaphragm with its upstanding housings for the exhaust pipes.  It'll be fine; don't worry.

 

And basically finished:

 

 

 

Just a bunch of plastic work.  On the engine (dry fit):

 

 

There are two sections that fit behind this aux blower section.  They come right after the carburetor, which is my next task.  Stay tuned.   

 

 

 

 

 

 

Edited August 31, 2020 by JayW

[Brett M]

Super impressive work.....wowsa

[Bil]

That engine truly is a work of art.

[JayW]

And now I get to show you the biggest folly I have committed yet on the R-2800 project - the carburetor.  Why did I spend two weeks on a component that is going to be practically unseen?  Well - part of the reason is that when I finish this engine, I intend to display it on it's own for a while, as I do other things for the Corsair like the cockpit or the wings, or the cowl.  And partly because R-2800's had big bad-a__ carburetors, and it would just be neat to do one.  Pretty weak....

 

The R-2800 had many variations, and part of those variations were the carburetor.  "A" and "B" series engines all had some version of the Bendix-Stromberg PT-13 carburetor.  In the case of the F4U-1's  and everything up until the F4U-4, it was the PT13-D4, which was an upside down (updraft) version:  

 

 

I have no idea why Vought wanted a carburetor on the bottom of the engine instead of on top like almost all other R-2800-equipped aircraft.  Any of you know?  That is the reason this work is such folly - it almost cannot be seen down there.   

 

Up until I found actual drawings of PT-13 carburetors and their components at AirCorps Library, I really had very little to go on to model it.  Vought drawings of the engine compartment stuff showed outlines but no good details.  My R-2800 book had some decent pictures:

 

  

 

 

That helped some but I could not scale much of anything.  Note that it looks like a great big single-lens-reflex camera.  It has a throttle body, a regulator unit, and a control unit.

 

Then I discovered that Aircorp Library had Fuel System information in their "components" section.  Thank you, Thank you!  Look:

 

 

Amazing!  And there were drawings of the components too (all three - body, regulator, controller, and more too).  Only thing is - there was nothing on the updraft -D4 version.  Only several versions of downdraft versions (right side up).  But that's OK - the versions shared many components or very similar versions of those components - some opposite hand, some upside down, etc.  That eliminated some of the guesswork.  And sadly, the drawing pictures are not crisp enough - where most of the dimensions cannot be read.  But I figured out a few though, which allowed me to scale everything else.  And using some pictures I have of the actual F4U engine which include the carb, I was off to the races.

 

Just using all types of EV plastic stock, and dozens of Meng nuts, I made the basic body (on the right) and the control unit and regulator unit (on the left):

 

 

Finished:

 

 

 

And temp placed on the (upside down) engine:

 

 

 

These super-duper close-ups reveal things I'd rather not reveal!  Looks much better from a foot or two away:

 

 

OK, here are the engine components completed  to date (after about 9 months of work):

 

 

Next is the aft section which is two components:

 

 

 

 

Good god - these are complicated.  With any luck I will complete these before the election!  Please stay tuned.

Edited September 12, 2020 by JayW

[LSP_Kevin]

Wow, Jay. Just wow.

 

Kev

[GROWLER 96]

Something tells me that now you need to throw out that plastic, and under this engine, you need to build the same plane.

[Hartmann352]

Things you would rather not reveal?!?!?!

Seriously??!! 
Dude, that is out-effing-standing work!!!!

The kind of work that I would display right next to the aircraft rather than installing it in the bird. 
I mean it! Superior work!!

 

Cheers,

Dave

[chuck540z3]

I am often bewildered how you and Peter Castle create such great parts, while the rest of us mortals are just gluing together the parts we find in the kit box.  Like Peter, your research, problem solving and execution is so much fun to watch.  Your engine looks fantastic!

 

Cheers,

Chuck

[JayW]

Ok the "intermediate rear crankcase":

 

 

Similar to the intermediate stage supercharger section already described, this piece started out as a lathe turning, and then a bunch of plastic add-ons.  I don't have any early-on pictures as they are so similar to what I already described.  But here are some pics of the basically finished part:

 

 

 

 

The large white flat area is where the "rear crankcase" will be mounted.  The round white flats are for mounting of the aux stage air exit ducts.  Wahoo!

 

And attached to the intermediate blower stage:

 

  

 

See that weird looking circuitous rectangular section pipe running horizontally on the near side of the assembly?  That is an oil passage pipe:

 

 

 

Here is what the engine looks like so far:

 

 

 

Coming right along.  The last remaining section of the engine is the rear crankcase:

 

 

This is also a lathe turning that starts out round:

 

 

...and then gets alot milled off:

 

 

Until it looks like this:

 

 

So much has to happen with this part!  You will see that next post, so stay tuned!

 

 

Edited September 19, 2020 by JayW

[brahman104]

Nice work Jay! If that was me I totally would have turned the hand-wheel the wrong way at some point and stuffed the whole part up!

 

Getting closer with this one.

 

Craig

[dodgem37]

Rock solid.

 

Sincerely,

Mark

[JayW]

6 hours ago, brahman104 said:

If that was me I totally would have turned the hand-wheel the wrong way at some point and stuffed the whole part up!

 

Oh Craig - that made me laugh.  So you know!  Heavily invested parts have gone to the trash bin over the years I have been using that lathe, due to that simple mistake and some more also, leaving a slobbering upset modeler to start over again!  

Edited September 20, 2020 by JayW

[brahman104]

On 9/21/2020 at 1:55 AM, JayW said:

 

Oh Craig - that made me laugh.  So you know!  Heavily invested parts have gone to the trash bin over the years I have been using that lathe, due to that simple mistake and some more also, leaving a slobbering upset modeler to start over again!  

And that's exactly the reason I'm considering converting my x and y axes on the mill to be stepper driven with button control...... it takes the "me" out of the equation! I actually have the complete CNC conversion kit, just need to find time to actually make it happen.

[JayW]

OK, so last post I showed this basic lathe-turned, and milled chunk of acrylic which was the start of the rear crankcase of the engine:

 

 

This section of the engine is basically the accessory drive gearbox, and boy is it full of "accessories".  It is also the place where the starter motor is mounted, and the input area for fuel and oil.  It is supposed to look like this:

 

  

 

Gulp.  Well you just have to attack it one step at a time.  And, this picture shows only the basic engine and none of the componentry that is mounted to all those mounting points!  Thank goodness AirCorps Library has an illustrated part catalogue of the R-2800-8, 8W, 10, 10W engines (which are the specific types for the Corsair and Hellcat).  What a vital part of my research.  That plus other specs of components and standards that can be found at AirCorps, plus some poking around the internet, and was able to fabricate some representation of each part of the rear section including accessories, with a minimum amount of guesswork.  

 

Here you see the laborious work part way through (actually most of the way):

 

 

Accessories are sprouting like buds on a bush.  In the foreground are the starter motor (left) and the clutch selector valve (right).  The starter motor is a brass lathe turning with plastic add-ons.  The rear crankcase in the back has many components on it already, all made of plastic shapes, and many many Meng nuts (I am going to have to order some more).

 

And eventually - voila!  The finished rear crankcase with everything on it that I could make and mount, at least with it separate from the rest of the engine:

 

 

There is so much here that I have attempted to label it all, for those of you who are interested:

 

 

 

Next post is coming soon.  It will be for a very large milestone, the complete R-2800-8 engine from stem to stern, something I have been working on for nearly an entire year now.  Stay tuned please!  Thanks for your patience. 

 

 

Edited February 16, 2021 by JayW