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

[chuck540z3]

Really nice work Jay, and everything is weathered perfectly for your subject.  How’s the airbrush thing going?  Second nature now?

 

Cheers,

Chuck

[JayW]

2 hours ago, chuck540z3 said:

How’s the airbrush thing going?  Second nature now?

 

I guess you could say that.  I really don't pay alot of attention to the pressure (I keep it around 20 - 30 psi), and I do not tweak the airbrush at all - the adjuster on the back of it is just dead weight.  I have been diluting my Tamiya paints (decanted) with about 50% thinner, and rarely deviate from that.  No science here.  The thing I like the most is more control over how much paint goes on.  Clean-up is a bit of a PITA, but not really bad.  I just wipe out the big stuff with a paper towel, pour in a bit of alcohol  and swizzle a brush around the bottom of the bowl, throw it out, pour a bit more in, swizzle again and spray it some, throw it out, extract the needle, clean it, reinsert, pour a bit more alcohol in the bowl and spray it til it's dry.  Seems to work for me.

[chuck540z3]

5 hours ago, JayW said:

 

I guess you could say that.  I really don't pay alot of attention to the pressure (I keep it around 20 - 30 psi), and I do not tweak the airbrush at all - the adjuster on the back of it is just dead weight.  I have been diluting my Tamiya paints (decanted) with about 50% thinner, and rarely deviate from that.  No science here.  The thing I like the most is more control over how much paint goes on.  Clean-up is a bit of a PITA, but not really bad.  I just wipe out the big stuff with a paper towel, pour in a bit of alcohol  and swizzle a brush around the bottom of the bowl, throw it out, pour a bit more in, swizzle again and spray it some, throw it out, extract the needle, clean it, reinsert, pour a bit more alcohol in the bowl and spray it til it's dry.  Seems to work for me.

 

Whatever works for you in your climate, works!  I use hot (hardware store) lacquer thinner to clean my airbrush, which dissolves almost anything that could clog it up, using roughly the same procedure.  One thing that I also use that might be helpful, is to use a dental brush in the paint bowl to nozzle canal, which can hide some containments left behind.  Like all of my airbrushing, I also use a chemical respirator and a paint booth to stop or vent fumes that are nasty.

 

Cheers 

Chuck

[JayW]

Next up - finally!  The tail gear mechanism.  This thing:

 

 

I'll spare you the individual part build-ups; here it is installed into the RH fuselage half:

 

 

 

 

Alot of 3D print parts in that build-up.  You see both the arrestor hook mechanism (sans hook) and the gear mechanism, including actuators, and a "dashpot" for the hook.  The oleo for the tail gear shock strut is hanging in space.  The trained eye will also see that the uppermost pushrod for the door operating mechanism is now in place.    The next picture shows the tail gear carriage and fork and wheel temp installed:

 

 

It took some doing to get a good installation that attaches to one side only.  But that's the only way to do it.  The carriage is removable at this point - a very good thing for when the skinning begins.  Don't want to break it off. 

 

Here is what it looks like with both fuselage halves joined (temporarily of course):

 

 

It's going to be just fine.  Note one side of the truss is bent out of the way.  I will have to disconnect the RH chain drive to allow that truss strut to be properly installed; I've known that for months.  No prob.   Note a control cable (painted fishing line) taped to one side - that must be routed during LH/RH fuselage join.  It's going to be very difficult.

 

Just a preview of how the tail will be oriented to the ground:

 

 

That extension is somewhere between full gross weight and empty weight.  I'm a little excited!  

 

I look around and suddenly I realize the next step is joining the fuselage halves.  Then skinning begins.  Challenging skinning.    Here are both halves ready to be joined:

 

 

Please stick with me.  Adventures to come.

 

Edited February 12, 2023 by JayW

[Oldbaldguy]

I forget:  Hook or no hook?

[JayW]

57 minutes ago, Oldbaldguy said:

Hook or no hook?

Leaning with giving it the hook.  If I were to be more authentic with history though, I'd leave it off.

[Greif8]

Very, very nice scratchbuilding Jay.  

 

Ernest

[Jim Barry]

Wow!!

[daHeld]

That wheel bay looks so great.
 

I guess to be able to pose any more challenges for you, your next project will have to be something scratch-built.

Edited February 17, 2023 by daHeld

[JayW]

14 hours ago, daHeld said:

I guess to be ale to pose any more challenges for you, your next project will have to be something scratch-built.

 

Well thanks!  This build has offered (and continues to offer) some of the most serious challenges I have ever encountered while modeling.  An entire scratch build - I cannot even wrap my head around it yet, but yes the thought has occurred (would be a P-51 if I did it).  A while ago I purchased another 21st Century Toys P-51 off E-bay for large coinage, for the purpose of replacing my very first 1/18 major remodel (a P-51D "Miss Velma"), which is pretty cool but is now long in the tooth and did not benefit from much of the lessons learned from builds I have completed since, and it shows.  The purchase may however just be a waste, as I am less and less willing to live with the inaccuracies the model possesses - inaccuracies that just cannot be corrected without just tossing the whole thing (blunt wing leading edge, excessive wing thickness, wrong shape of radiator inlet, wrong shape of carb air inlet smiley face, windshield and canopy shape, etc).  

 

In the mean time, it is going to take the rest of this year probably to complete Jolly Rogers #17!  

Edited February 14, 2023 by JayW

[KiwiZac]

Ever seen a 21st Century Toys Stuka, Jay?

[JayW]

This post will not be for all of you, but for those who are interested in how an aircraft landing gear works - namely the F4U tail gear - I offer my observations.

 

For the longest time, I was a bit bewildered by the F4U tail gear.  Couldn't quite figure out how it worked.  Turns out it's quite simple, when you take away the arresting hook mechanism, which is right on top of it but is really independent from it.  I have observations on that mechanism too, but for another time. 

 

Here is a picture of the tail gear mechanism, all by its lonesome (in Rhino 7):

 

 

 

It is basically two links supported by a heavy bulkhead (the upper link and the "scissors link"), one of the links being collapsible in one direction (the "scissors link), so actually it is two.  And these links are driven by a linear hydraulic actuator.  The parts are labelled above.  The carriage and shock strut are simply attached to this linkage.  Note the labelled "hard points".  These are fixed (non-moving) attach fittings on the fuselage.  All the red circles are merely paths that joints follow as the mechanism operates.

 

Collapsible I say?  This is the key to the mechanism.  Look at a close-up of the scissors link with the mechanism in an intermediate position:

 

   

 

Note it is partly folded up around a central pivot joint, showing stop surfaces on both link halves.  Those stop surfaces contact one another when the link is fully extended, preventing the link from folding in the wrong direction.

 

Here, I show four different positions for the mechanism, with only the two links and actuator shown.  Gear fully extended, 1/3 retracted, 2/3 retracted, and fully retracted:

 

 

 

 

Look how the actuator changes length from fully extended to fully retracted.  Look how the upper link swings back and forth.  And look how the "scissors" link goes from fully extended to folded to fully extended again. 

 

These four mechanism positions overlain on top of one another:

 

  

 

This mechanism, of course, is designed to function in two positions only - fully retracted or fully extended.  All other positions are transitory.  In those two positions, there is no load on the actuator.  None.  The weight of the aircraft, or the shock of a landing or a bump is taken purely by the carriage, the shock strut, the upper link, and to a small extent the fully extended scissors link.  It's beautiful.   The only way the actuator sees load is in transitional positions, where the scissors link is in a folded orientation.  This means the actuator doesn't have to be very strong and heavy.  Just like it's supposed to be.  Also, the geometry is such that the scissors link is lightly loaded at all times.  When the gear is extended, where it sees its most severe loading, the upper link and shock strut are almost in a straight line - the scissors link only makes sure the two don't collapse.  When the gear is retracted, or in a transitional position, the scissors link(s) only see a factor of the dead weight of the gear carriage, the fork and the wheel/tire.  That is why my scissors link is so thin and spindly looking.  

 

I have stated before that IMO the Corsair is chalk full of unnecessarily complicated contraptions ("Rube Goldberg").  But the main and tail gear - they are engineering marvels.  Vought had some crack engineers in the landing gear group.

 

Next post - fuselage skinning!           

 

 

Edited February 15, 2023 by JayW

[Paulpk]

Jay, is this going to be strong enough? Looks wise it is great but strength wise…good candidate for brass construction.

[JayW]

1 hour ago, Paulpk said:

Jay, is this going to be strong enough? Looks wise it is great but strength wise…good candidate for brass construction.

 

Is there a specific part you are concerned with?  Or just the whole tail gear mechanism?  

[JayW]

On 2/14/2023 at 4:11 PM, KiwiZac said:

Ever seen a 21st Century Toys Stuka, Jay?

 

I have now, complements of E-bay.  Now that would be a project!  For my subjects however, I want to have access to alot of real definition (if not drawings, then lost of other publications where I can determine what needs to get fixed).  Don't think I could find alot on the Stuka correct me if I am wrong.