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Grumman Goose JRF-5, Conversion to Portuguese Navy G21B


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So this kit is both my first major resin build and, with the Signifer G21B Trans Kit, also my first full conversion.


Sadly not in 1:32, but this subject simply isn't (at least presently) available in my preferred scale. So 1:48 will have to do.


I've added resin components to other builds and done a fair bit of scratching, but this is stepping waaay out of my comfort zone. I have each of you as inspiration, and I plan to plagiarize shamelessly from your techniques and ideas.


I love the Signifer kits and the owner is a joy to work with. The Goose kit is already a beauty, with tons of resin components. The G21B conversion kit changes the airframe from amphibian to pure seaplane, completely replaces the cockpit, adds a dorsal gun port and - almost a kit in itself - the beaching trolley.








I already had the Goose kit in my stash, and I ordered the conversion kit specifically for this GB - thanks for providing the inspiration! It arrived in my mailbox today, so I'm starting to plan my approach now.


I've loved the Goose since I first saw one many years ago. It's the one aircraft that I would actually love to own and fly (given time and opportunity) and I hope to do it justice with this build.


Later on I'd like to do a "Personal Fantasy" build of the Goose that I'd have for myself, using this same Signifer kit as a starting point.

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When I was a kid (and this time is long gone ;) ) I had the 1/72 Airfix-Goose built and I share your feelings about that plane. I always wished to own one, the real thing I mean. Only the Catalyna (the Cousteau one) and the Goose did that to me.

I wish you a lot of fun with that build and maybe you got an avalanche started and soon there will be a decent 1/32 Version of the bird (HPH, do you copy?)


Cheers Rob 

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I will follow this one...


I was to get this conversion some time ago but its in the wrong sclae but i doubt that wil lbe a Portuguese Goose in 1:32...


Maybe I will get it soon!

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  • 2 weeks later...

So the first step happened...  boxes opened and inventoried.

the base kit is about 40% resin - all interior parts, control surfaces, engines, cowlings, floats and so forth.


to this I'm adding the G21B conversion kit.  This replaces the cockpit in its entirety and includes the external components that convert the airframe from amphibian to pure seaplane, along with other G21B specific details such as gun mounts. And beaching gear.


i will start mapping the build process this coming weekend.  It may be a couple weeks before I bring out the paint and cutters - I want to have a clear view of the build first.

the quality of the resin components in both kits is superb - I haven't found anything but the tiniest of casting flaws and the detail is crystal clear.  I'm truly looking forward to this.


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One side note to this... so far as I've been able to determine, only 12 of the G21B model were ever produced, all for the Portuguese Navy.  That Signifer took this on as a conversion kit is truly impressive

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  • 3 weeks later...

I'm going to cheat a bit with the beginning of this build - since I have two complete resin cockpits (one from the base kit and one from the conversion) I'm going to use the spare to do an update of my resin painting skills.  It's a rare thing to have that kind of opportunity so I'll take full advantage.


i've focused so much on the wood and metal side of things for the last while that I need a refresher course! :D


Well, that and I'll be using some paints that I'm not familiar with...  so watch over my shoulder as I fumble through and scratch my head in public

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So... As the Picket Boat project is finally winding down, I'm turning my full attention here.  This kit is gorgeous - truly gorgeous.


Two spruces of plastic for the fuse and wings, a small clear sprue for one of two windscreen options and bag after bag of beautifully-cast resin.





one thing I found as I started to look closely is that one of the cockpit castings is broken.  Fortunately the entire cockpit is replaced in the G21 conversion kit so this isn't an issue.  


The cabin windows are supplied via pre-cut acetate, and there is a vac-form option for the windscreen if one doesn't like the clear plastic part.


Also included are copper wires for the engine plus hard wire for the pitot and other rigging bits.




The conversion kit contains a number of pieces beyond the replacement cockpit already noted.  There are PE pieces for the gunner's hatch, new arials, pitot and a complete beaching trolley.




There will be some major surgery needed on the fuselage before I even cut it off the sprue - one feature of the G21 is that it converted the Goose from an amphibian to a dedicated float plane.  The conversion kit addresses this by replacing the main gear bay panels with cover plates.  To install these requires cutting out the existing panels and replacing them with the resin pieces from the conversion kit.  So I have my work cut out for me... :)


An unusual thing in this kit is that the fuse is closed very early in the assembly process, with most of the interior components installed through the space where the wing attaches at the top of the fuselage.  Because of this, the resin fuselage panels and bow compartment will be the first parts I address for the build.


There's a large casting block on the bottom of the bow compartment - removing and fitting this will be my job for tonight.


For painting and such, I'll be using Tamiya acrylics for the interior and an Alclad NMF exterior.  I spent a happy hour at my LHS stocking up on paints today - this is going to be fun!!!




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You can't stay out of the water with your projects :lol:, you just switched from wood and metal to resin and plastic.
I can't wait to see this one develop, albeit it looks like a lot of work ahead to me. Good luck with that.

Cheers Rob

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I'm working on the bow compartment fitting.  This was cast in a single unit, which has both good and bad points.




On the good side, it greatly simplifies construction in that there are no seams and it will assist in alignment of the fuse halves. 


(Yes, I know there's a bit of cleanup yet to do on the plastic bits - I'll do that once I get the casting where I want)




On the bad side, the fit is more than a bit fiddly and the top edges of the casting will be thinned almost to invisibility.  




I'm going to have to extend the tops of the frames a bit with evergreen, as they will be visible through the open bow hatch.  That is perhaps the one objection I have with the single-casting approach.  On the other hand, it's always fun to add on to the supplied parts for improved fidelity.


there are a few points where this is an issue with this kit.  I'll touch on these as I work through each component in the build.


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Finished cleaning up the rest of the major castings for the front interior.


The bow compartment, cockpit floor/IP and cockpit rear/upper section are individually cast.




The bow compartment and cockpit floor get installed before closing the fuselage halves.  Everything else is installed later, through the wing opening.


The three pieces fit perfectly after removing the casting blocks - great work by Signifer






With a bit of luck, I'll be able to get a coat of primer on these in the next day or two and start adding in the details.  Rudder pedals are going to be a bit touchy - not much room to manouver under the IP... :D


Everything else is easily reachable, and the detail in these castings is impressive.  Getting them painted up and ready to install will take a day or three...


then I face replacing the landing gear wells with their cover plates - a bit of surgery that will hopefully leave the patient intact afterwards! ;)



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  • 2 weeks later...

There is actually stuff happening on this build, albeit slowly at the moment.  When I have large chunks of time I spend them in getting the Picket Boat wrapped up.  The Goose is getting those odd bits of time when I work from home or just have a few minutes in the evening.


Even so, there's progress.  Nothing photo-ready just yet (all the pieces pretty much *look* like they did in the last pics I posted).  But still...  progress.


I'm finding that I have one complaint about the way this kit was engineered.  There are no alignment pins *anywhere* to assist in the precise location of some of the major internal components.  This makes fitting some of the pieces much trickier than it should be.  The resin castings for the bow compartment, cockpit, cockpit back wall/cabin door, cabin floor and cabin back wall (plus a sub-floor beam used to support the bottom of the cockpit) all have to be shaped to the internal curves of the fuse, all without precise location indicators.  I have to make good use of my eyeball-micrometer, compare to pictures on the 'net and *feel* the fit as it develops.


sooooo...  I take a deep breath, sand a bit, test fit, sand a bit more, curse, have a drink, test fit again...  Lather, rinse repeat...  It's kind of a meditative thing, come to think of it... :)


At the rate I'm going I have about three or four hours of work before the pieces are all well-fitted.  At that point I'll be able to actually start gluing and painting the interior details.

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I had an "ah-hah" moment today, when I realized that the conversion kit cockpit was a smidge wider than the original kit cockpit, which is one of the things causing fit issues.


As it happens, the replacement panels that replace the original mainwheel bays are a bit thinner than the kit plastic.  By about half, actually (the kit plastic is almost 1/16" thick).






Ok, so it was time for major plastic surgery.  Three conference calls and a few "what was I *thinking*" moments later...  Replacement panels installed.  Need a touch of filler as they are not a *perfect* fit (especially where I decided - a bit late in the process) to save a rivet line that I'd otherwise have to replace.


nevertheless...  here they be.


Where and how...




Starting to rough-out the cut...




Dunno why they put frame lines on these as they will be completely covered...  not to mention that they're like half the thickness...




And... done for the moment.  




They need a touch of filler at the top, as I changed my mind in mid-stream (not a thing to do while sanding!!!), but I'm happy with my first major hack-job on an otherwise pristine bit of kit plastic...

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After much sanding, cursing, taping, untaping, cursing again and re-taping, I finally have all the internal modules fitting properly (excepting the windscreen and frame, which I've not yet detached from the clear sprue).  Yippee! :D






At the moment, it looks more like a cast member from "The Mummy" than an aircraft, but it's all good. :)


So now I can finish cleaning up the edges and openings, get some primer applied to the interior bits and start painting...  


I won't add the canopy and close things up until the modules are painted and installed. This promises to be a bit of a pain - I'll use a slow-drying epoxy or gel CA since the windscreen, modules and floor all have to be adjusted a bit within the fuse halves once they're joined.  


This is the one real objection I have with this kit - you can't glue the modules on one side of the fuse and know that they'll match the other side.  This means you have to close the fuse and fiddle with the modules inside to get them settled - a tricky proposition once glue is applied!


As for finishing, the cabin of the G21B is considerably more spartan than the other variants.  The bombardier actually laid on a pad on the floor and the bombsight was mounted through the hull between frames.  It's not clear from the documentation whether the floor panels involved were removed permanently or whether they could be mounted/dismounted to allow seats to be mounted for passengers:








For the moment, I'm working from the assumption that the floor panel(s) could be removed/replaced.  I don't have to glue anything down for a while yet, so I have time to both do more research and to decide how I want to approach this particular aspect.  It would be kinda fun to replicate the views above, but it would require scratching a ton of extra detail that's all but invisible through the windows.


i'll decide on all that a bit later...

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This is something I think I *will* add to the build, as it will be easily visible in the open bow compartment...



At a minimum, I'll work out the mount and such.  Tracking down the appropriate AM gun will be a fun challenge...

Scratch that last - Gaspatch has exactly what i need...  Ah, the power of the internet! :D


Edited by crazypoet
Updated DOH moment
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Something I've noticed on the reference photos is that they seem to be of a brand-new aircraft at the factory.  That aluminum is too clean and polished for anything that's been occupied or flown for more than about 30 seconds. Some of the skin has almost a mirror polish, best seen in the reflection of the bombardier's seat headrest in the panel just to the left.




The instructions from Signifer call for a Zinc Chromate interior.  Is that something that would have been done at the factory or after delivery or perhaps not at all?

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OK... Bear with me while I think out loud here...  :)

All the photo documentation of the G21B that I've seen (mostly from the Signifer site) show NMF inside and out, except for the cockpit, rudder and hull below the waterline. 

So... that's what I'll go with.  I'll use Zinc Chromate for most of the cockpit and bare aluminum for just about everything else.  I'll dirty things up a good bit as it won't be "factory fresh".

I'll build the Nav table and add in the aux fuel tank as these are quite visible through the windows, but I'm not going to worry about the gunner's compartment.  I'm adding the fixed .30 MG in the bow compartment, which means I need to work out the hull opening and how it was sealed when not in use.  I'll also at least mock-up the hull openings/plugs for the bombsight and drift indicator.

I may live to regret these decisions but if I don't get them written down, I'll back out when I get frustrated...  Y'all get to watch over my shoulder and remind me that I promised an all-NMF bird!  :D 

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  • 2 months later...

It's been quite a year!  I had a change in familial status and relocation to a new space, both of which contributed to a long delay in getting *anything* done! 


I'm getting settled, and should have my work space functional in the next week or so, so I can pick back up where I left off in April...


Life is quite the adventure...

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  • 2 weeks later...

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