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

[Gazzas]

Wow, Jay!  That chain is amazing.   Another impressive improvement.

[JayW]

3 hours ago, monthebiff said:

Also check out Studio 27 and Top Studio as they make excellent chain sets which you build yourself so you can get the correct length you require!

 

Regards. Andy 

 

I did Andy, and they all appear to be 1/12 scale - just too large unfortunately.  Did I err?  Not to mention expensive, although cost is generally no object in my builds. 

Edited October 23, 2022 by JayW

[Citadelgrad]

Very nice solution, Jay!  Like you, i seem to stress over particular issues on a build, even delaying tackling it over my self generated doubts. Then, when i actually buckle down and tackle the issue, it turns out to be tough but manageable. 
 

this chain really looks great. 

[Thunnus]

That's nuts, Jay! Scratch building a chain, link by link, in 1/32 scale... WHO does this stuff?  

[LSP_Kevin]

1 hour ago, Thunnus said:

That's nuts, Jay! Scratch building a chain, link by link, in 1/32 scale... WHO does this stuff?  

 

1/18, though, not 1/32. A bit easier, but still crazy.

 

Kev

[JayW]

19 hours ago, LSP_Kevin said:

A bit easier, but still crazy.

 

Well only crazy because it is tedious, and parts are small.  I found the work isn't as bad as some other tedious things I have done - like 18 radial engine cylinders made from scratch.  Or 18 cowl flap mechanism components.  Those chain drive mechanisms (at least their lower portions) are going to be visible enough to make it worth it.   You'll see!  

[JayW]

Well, I've been a Rhino operating fool lately.  Lotsa hours.  That's just about all I have been doing for the Corsair.  But I think I am done.  The tail wheel bay is integrated, meaning any clashes have been resolved, and all components have been 3D represented to make sure everything fits.  Also, I have made 18 separate 3D details that are going into a 3D print order. 

 

I think the tail gear doors were the most difficult items to Rhino model.  I don't want to use the 21CT parts:

 

  

 

Cheezy looking, as usual.  

 

Here are some shots of the Rhino model:

 

 

 

 

 

 

As you can see, Rhino offers several types of rendering options, so I like to change it up a bit for the pictures.  I attempted to create some more convincing inner structure for the door details.  They are going to be far better than the toy doors.  You may notice that there are two doors per side - a fwd door and an aft door.  The fwd doors are driven by the chain drive that has already been discussed ad nauseum.  And the aft doors are driven by the fwd doors, the two linked to one another by a small turn barrel link (the link is not Rhino modelled, but will be on the real model). 

 

In addition to the four gear doors, a host of other details will be 3D printed.  Here they are in Rhino:

 

 

 

 

All are either details I am not confident I can make, or just don't want to.

 

And with that, I will send off the print order to Tim (gonna be an expensive one!)  And I can now start hitting the plastic!  First is to finish up the chains (I know, I know  ), then dremmel work on the inside of the aft fuselage, then alot of scratch building of frames etc.  Will update soon.  Take care and Happy Thanksgiving!

 

 

Edited November 1, 2022 by JayW

[Jim Barry]

Those Rhino pics are like DeVinci on CAD!  Love it. It’s killing me too. My Bearcat is not this class and I have to keep saying "that's ok, it's ok, you’re fine" 

Edited November 1, 2022 by Jim Barry

[LSP_Kevin]

Wow, Jay!

 

Kev

[Oldbaldguy]

11 hours ago, JayW said:

  They are going to be far better than the toy doors.  You may notice that there are two doors per side - a fwd door and an aft door.  

 

 

What?????  Two doors per side??  Who knew?  The first thing that popped into my head was, “Why??”

[JayW]

34 minutes ago, Oldbaldguy said:

 Two doors per side??  Who knew?  The first thing that popped into my head was, “Why??”

 

Yeah - it is so that when the tail hook is removed, the aft doors can be closed semi-permanently.  The split is situated just aft of the space envelope for a retracting tail wheel.  Why - I am not sure, except that with an additional fairing aft of the aft doors that covers the ugly gap where the hook head resides, a more aerodynamic profile is obtained. Drag reduction must have been enough to make it worth it?  Dana Bell volume 8 has a discussion on this.  And if you study various early (land based) Corsair period pictures you will notice that many have the aft doors fixed closed.  Never noticed until now!!  I do not know what keeps the aft doors in place once unlinked from the forward doors.... must be some fixed beam added by kit inside the compartment where two links can be attached to it and the lugs on the doors or some such thing.  I searched through my VF-17 book and it appears that they did not modify their aircraft to fix the aft doors in place even when tail hooks were removed.

[JayW]

All right!  Enough with the Rhino modeling.  I have broken ground on the tail gear bay.  Haven't got a ton done yet, but it's progress.  First, I felt the need to get a bit of skinning done in the vicinity of the gear bay, mostly for the "piano hinge's" that will attach the doors.  I'd rather the skins were there first.... 

 

 

Those panels are easy; the fillet fairings for the stab and fin will be uber-difficult.  As will be the tail cone skinning.  I will need coaching from the skinning experts.

 

There are several important bulkheads inside the gear bay:

 

Sta 288 tail gear bulkhead - forms the forward end of the bay, is where the tail gear attach, and also other important hard points

Sta 310.656 fin bulkhead - where fin spar is attached

Sta 346.16 stab bulkhead - where stab spar is attached

Sta 371.5 tail cone bulkhead - forms the aft end of the bay, attaches tail cone

 

Also there are many lesser frames.  What you see here is the Sta 288 bulkhead and the stab bulkhead, plus a "truss".  First the Sta 288 bulkhead:

 

 

This part is actually four parts.  A left frame and a right frame (with door operating structure), a bottom frame (with the gear attach fittings), and a top portion (with the gear strut support fitting).  The top and bottom portions will wait until LH and RH fuselage are joined, weeks from now at least.  The LH and RH frames you will see here installed

 

The stab bulkhead:

 

  

 

Not much to say except it was challenging to get its shape right.  All that clap trap on top of it is meant to depict the stab spar attachment. 

 

The installation so far:

 

 

 

That truss is an interesting feature.  Corsair experts know it's there.  Note it terminates on the stab bulkhead and the Sta 288 bulkhead.  Apparently, the gear door cutout compromises the strength of the aft fuselage enough to where it needs a reinforcement.   I show only one leg of the truss, but it ends up with its opposite leg as well to form a triangle (that's what trusses are).  So it is meant to take side loads, and those side loads would come from the fin and rudder.   

 

OK, that's all for now.  Next post I anticipate frames right behind the 288 bulkhead, which will allow me to put in the door drive chains!  Let's see how it goes. 

 

Have a Happy Thanksgiving, those who celebrate it.   

 

 

Edited November 16, 2022 by JayW

[LSP_Kevin]

Amazing as always, Jay!

Kev

[brahman104]

Man that is intense! You have been busy Jay . The aft fuselage is rapidly coming up to par with your forward fuselage effort.

 

Yeah those little fillets will be interesting. You may even want to resort to some pewter sheet for those bits instead of litho.... It may just be a little easier to work the tight curves.

 

Craig

Edited November 16, 2022 by brahman104

[Oldbaldguy]

I would expect that off-center or less than optimal arrested landings would put some pretty violent torquey side loads on the 288 bulkhead at the tailwheel attach points.  Same with a wonky landing that ends up in a ground loop or something similar.  So the truss would help transfer those loads past the gap in the structure left by the wheel well opening, taking the place of the fuselage structure that isn’t there.  Did I get that right or miss it entirely?