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

[Rocat]

Wow. Your work is just amazing. Thank you for sharing it.

[wingman777]

Absolutely incredible work of art, unbelievable detail and accuracy.  

[TAG]

Congrats on the huge milestone, Jay. Also, as expected, your skinning skills are rapidly catching up to your outrageous scratch-building talents. This is gonna be your magnum opus, can't wait for the next update!

 

 

[JayW]

A short post just to keep everyone up to date. 

 

So on to the firewall.  When I first saw this picture in Dana Bell, I was impressed for some reason:

 

 

That is what the firewall is supposed to look like.  Look how it sits on top of the main spar.   Also note the four hard points for the engine mount truss (two on the lower spar chord, two on the firewall at the longerons).  My firewall must have all that stuff.  

 

The lower portion which I showed on the bench in a previous post, was installed.  The challenge there was to have it fit accurately to the curved upper chord of the main spar.  Here, the Rhino 3D model was indispensable, even with its inaccuracies.  The upper portion was easier:

 

 

Back away:

 

 

This is the beginnings of the engine accessories compartment, for which I have very big plans.  

 

Before I dive in fully though, I have to skin the belly of the fuselage:

 

 

Yes - the "Blue Box 2005 made in China" engraving will disappear!   That nasty joint between the fuselage and center wing will also get skinned over.  That is what you will see next post.  Til' then take care!  

 

 

 

   

Edited February 28, 2022 by JayW

[Oldbaldguy]

Okay, let me see if I understand what I just read:  The cut line in Dana’s book says there was a decal on the big oil tanks that said to limit the tank to 20 gallons of oil (even though it would hold more) unless the airplane was carrying a full drop tank at which point you could fill the bigger oil tank to the top - more gas equaling more time in the air.  That is confusing because I assume you could fly the airplane safely with the bigger tank topped off if you wanted to without breaking the CG envelope.  If that were true, then that means the increased oil capacity came about because that big P&W burned or dumped so much oil per hour that you would be running dangerously low on oil after flying the additional hours provided by the drop tank if you were limited to only the original twenty gallon oil tank.  If you weren’t carrying additional fuel, then you didn’t need to haul around all that extra oil because twenty gallons was plenty enough to cover a flight on internal fuel only, thereby saving weight that could be allotted to something else, I guess.  Does that make sense or have I just confused myself?

[Landrotten Highlander]

sounds reasonable to me.  Only carry as much oil as you need for the flight, leaves more room for payload (where possible). CofGis not considered to be severely nfluenced that way.

[dodgem37]

Fantastic work, Jay.

 

Sincerely,

Mark

[JayW]

2 hours ago, Oldbaldguy said:

Does that make sense or have I just confused myself?

 

Yup - I have thought on this as well.  Warning?  I could not find that decal.  The bigger tanks do have decalcomania, but only to specify the tank volume (28 gal max).  But nothing I found states to limit oil to 20 gallons for missions without external tanks.  Other than weight savings, I cannot think of a reason to not just fill it up prior to a mission. 

[KiwiZac]

Magic.

[Johnny Cloud]

Truly spectacular!

[JayW]

A bit more on that larger oil tank, which was introduced when centerline external store provisions were introduced.  It was bandied about by yours truly that the original Corsair oil tank held 20 gallons, and the later larger one held 28 gallons.  

 

Here is the placard on the original tank:

 

 

And the placard on the later tank:

 

 

Now I am not sure why each tank has two values - I guess not all oil in the tank was useable (some left over).  Perhaps we should be comparing useable oil, which would be the smaller value I think.  In that case the comparison is 20 gallons versus 24.25 gallons.  A difference of 4.25 gallons.  A gallon of oil weighs roughly 7 pounds, so that makes about 30 lbs total.  

 

I still cannot find any placard that states to limit oil to 20 gallons for missions w/o external tanks.  But at a minimum, it units out there fighting must have been informed by Vought that that was the case.  30 lbs is 30 lbs.  When I was in the business, we would sell our children for a 30 lb weight savings that was "for free".  That makes that turn just a bit tighter, that climb just a bit quicker.  That fuel burn just a bit less.  All that was important.

 

Lastly I am amazed that much oil is used on these WW2 era engines.  My word.  

Edited March 1, 2022 by JayW

[Oldbaldguy]

1 hour ago, JayW said:

A bit more on that larger oil tank, which was introduced when centerline external store provisions were introduced.  It was bandied about by yours truly that the original Corsair oil tank held 20 gallons, and the later larger one held 28 gallons.  

 

Here is the placard on the original tank:

 

 

And the placard on the later tank:

 

 

Now I am not sure why each tank has two values - I guess not all oil in the tank was useable (some left over).  Perhaps we should be comparing useable oil, which would be the smaller value I think.  In that case the comparison is 20 gallons versus 24.25 gallons.  A difference of 4.25 gallons.  A gallon of oil weighs roughly 7 pounds, so that makes about 30 lbs total.  

 

I still cannot find any placard that states to limit oil to 20 gallons for missions w/o external tanks.  But at a minimum, it units out there fighting must have been informed by Vought that that was the case.  30 lbs is 30 lbs.  When I was in the business, we would sell our children for a 30 lb weight savings that was "for free".  That makes that turn just a bit tighter, that climb just a bit quicker.  That fuel burn just a bit less.  All that was important.

 

Lastly I am amazed that much oil is used on these WW2 era engines.  My word.  

I picked up on the 20 gallon limit thing from the verbiage below the photo of the firewall you posted a bit ago.  The author says the big tank was placarded to 20 gallons without a full drop tank on the airplane in order to “save weight.”  If I hadn’t read that part, I would never have gone down the if-then rabbit hole to make sense of it.  What confused me the most was the comment that the bigger tank weighed less empty than the original tank, but it, of course, held more oil so the plane captain was supposed to leave some out to save weight.   That’s what gave me a headache until I noodled it out.  Is it safe to assume you will fill yours with the requisite twenty 1/18 gallons?

[JayW]

Update time.  OK, last I posted progress we were here:

 

 

The belly of the forward fuselage, of course, to be skinned over.  That picture has three items of interest.  One, on the lower right, is the prominent and ugly splice line between the fuselage part and the wing part.  Next item forward is the painted over "bombing window" (I discuss a bit more below), and further forward right behind the belly door opening is the area where the engraved "Blue Box" printing is.  That's gotta go!

 

Items 1 and 3 got covered by aluminum skin- a big improvement for the fuselage belly:

 

 

This skinning (six belly panels) was done with the litho plate provided to me by Peter Castle (Airscale) - the fourth material I have used so far to skin this bird, and the best material yet (recall I began skinning using annealed shim stock, then coke can alum, then heat treated shim stock).  My thanks to Peter for going through the trouble (and it was trouble) of sending a goodly amount of this plate to me overseas.   Note I also skinned over the lower wing-to-fuselage splice angles.  The little white tear drop is the highly aerodynamic fairing for the pee tube exit. 

 

Now that bombing window.  The first F4U's (birdcage types) had bombing windows, supposedly to aid in aiming bombs.  Little bombs - the original F4U's did not have a very impressive capacity for external stores, unlike the -D's later on, which had incredible capacity.  I suspect the window was part of the Navy spec that Vought used to design the Corsair.  I wonder if the early F6F-3 Hellcat, which I suspect was designed to the same spec by Grumman, also had a bombing window....  Anyway here it is in Dana Bell:

 

 

Now, this window was discontinued at Bu No 17647 (line number 950), at least according to the drawings, which is the first F4U-1A Corsair and the first bubble canopy version.  Instead an access door was designed, attaching with approximately 70 screws (you REALLY had to want that access to remove and replace that many fasteners).  The bombing window must not have worked very well....wish I knew that story.  For reasons not clear to me, this change has escaped some of the model manufacturers who have done Corsairs.  Including 21st Century Toys / Blue Box, which went through the trouble of including a clear plastic window, on a model that is supposed to be a F4U-1D!

 

Before I decided to skin this beast, I was happy just to paint the window over.  But now that I am skinning, nothing less than a replica of the real access door would do:

 

 

 

Installed:

 

 

 

And then Ureka!  The belly skinning was done.  That is at least aft of the belly door.  Skinning forward of the belly door will wait until engine accessory compartment work has begun, according to a sequence plan I am developing with the purpose of providing as much access as possible for the various details I want to include in that compartment.  I am going to fail - it will be impossible to include it all.  The only question is how much of all that clap trap can I get in there.   

 

Part of that sequencing plan is the centerline external fuel tank provisions - two hooks - one forward on the engine mount ring, and one aft just below the spar.  Here:

 

 

This provision also started up with the -1A version, I believe (birdcage Corsairs didn't have it).  And the aft hook needed to be done now, not later.  Here it is; see if you can find it:

 

    

 

Closer (excruciatingly close):

 

 

The details were little nightmares of plastic stock, using tweezers and high magnification.  Another Vought rube-goldberg gizmo....then again I have not seen a bomb or tank release mechanism that is not complicated.  I will leave it at that.  I am not 100% happy with it, but geez - true micro-engineering.  Note also that I have puttied over some of the wing-to-fuselage paneling.  I will not be skinning those; instead I will try to use them as is, so I puttied over the stupid fastener dimples.  Prep of those panels will continue.  Part of my skinning plan; wish me luck.  BTW, weathering was done with Tamiya Weathering Master "oil stain".  A very dirty part of the aircraft.

 

Next on my sequence list is the belly door actuator and its two hydraulic lines - attached to a bracket on the spar (you can see that bracket in the last picture, just above the hook mechanism, and the two little hydraulic bulkhead fittings above the bracket).  That is in prep to install the belly door itself - something I don't want to do yet, because the opening for the door provides good bottom-side access to the engine accessories compartment.  But I think I have to in order to assure access to the areas where the door will be glued down.  Got that?  Suffice it to say that good sequencing on this project is vital.

 

Bear with me as I complete some relatively mundane tasks, before the fireworks in the engine accessories compartment begin!  Thanks for looking in.  Ta ta!

 

 

 

 

 

Edited March 9, 2022 by JayW

[TAG]

 

Out-STANDING, Jay, just outstanding work.

[Hans]

Jay, looking at your work I can't help thinking at times I am looking at a 1:1 Corsair.