Monogram 1/48 Thunderbolt Floatplane

KIT #: PA-187
DECALS: Two options
REVIEWER: Dale Rannals
NOTES: Kitbashing at its best.

Koster XP-47H vac/resin set: $18 from Mr. Koster . Medallion Models p-47N wing conversion: $8 from online auction. Spare floats from a wings Kyofu vac kit


Anthony pushed the throttle forward and the big Hemi engine roared to life.  The sound was unmistakable, you could almost hear each of the sixteen cylinders as they forced the big propeller to claw its way through the air.   The large plane shuddered as it picked up speed….faster and faster and still the water did not want to lessen its grip.  Finally, after what seemed an eternity, the water let go, and the Seabolt was airborne.

After a quick scan to ensure the others were with him, the course was set and they started climbing.  Settling out at 26,000ft, they set the mixtures to the most economical settings….it was going to be a long flight.  Anthony scanned the instruments and looked over his craft.  “What a strange bird” he thought, “and what a strange set of circumstances that created it.” 

Guadalcanal, early 1942.  After taking the airfield being built by the Japanese, the Americans realized actually finishing it was going to be nigh impossible.  With the incessant bombing by the enemy aircraft by day and the shelling by ships at night, the Seabees had all they could do to fill in the holes, let along make any progress before the next set of bombs fell.  The navy’s carrier aircraft did what they could, but the carriers were always needed elsewhere….that and the Navy was not keen to risk the only two flattops that escaped the Pearl Harbor attack back in June of ‘41.

So attention was turned to floatplanes that could defend the area without needing the airfield.  Luckily Grumman was producing some Wildcatfish fighters, but not nearly enough, and their performance left something to be desired.  Something else was needed.  Grumman and Chance Vought both hurriedly worked on adapting their new Hellcat and Corsair fighters to floatplanes…….and actually they succeeded in commendable time, but for one small factor.  Quite a surprise actually, but it seemed the P&W R2800 engine didn’t play well with water.  The awesome engine just didn’t like getting cold water splashed on it.  Cracked cylinder heads were an all too common problem…the test pilots seldom knew how many working cylinders they would still have once airborne!!  Surely this would not do for a combat aircraft.  So while P&W struggled to find a solution, the race for another engine began.

Enter the oddball.  Republic, never a favorite with the Navy, came forward with a solution.  They were just finishing up testing the XP-47H Thunderbolt with the Chrysler IV-2220 16 cylinder engine and GE CH-5 turobosupercharger.  Chrysler had just finished the 2600hp, 1000hr test mark and was ready to go into full production.  Unfortunately for them, the Army was well satisfied with the P-47J Superbolts starting to come off the production lines, and the “H” offered no performance benefit.  So here was a great airplane/engine combination with no future.  But Republic had kept a keen eye on the situation in the Pacific and had developed a floatplane version, with a new wing, on its own.  The wing, slated for a different long range project, extended the span to incorporate more fuel.  The floatplane version added even more fuel in the space of the wheel well area, which obviously were not needed here.  After a few minor teething troubles were ironed out, the P-47H Seabolt was put into full production.  It was just what the Navy and Marines needed, a very long range, high speed, high altitude fighter that had no need for dirt to land on. 

They had the speed and maneuverability to defend recently taken islands until airstrips could be finished and their land based cousins continued the job.  Then they would proceed to the next area, before an assault started, to soften up and tire out the enemy.  Once production got to full tilt and more squadrons were formed a new mission emerged:  long range interdiction.  Extreme range missions would be flown to hamper rear areas and supply lines, forcing the enemy to try to protect everything, everywhere……...

……extreme range indeed, Anthony thought as he again checked his position on the map.  He was sore and stiff……..his parachute wasn’t all that comfortable to sit on for a few minutes, let alone several hours.  Up in the thin air he barely made out the coastline ahead, but he did notice the moving specks several thousand feet below.  Calling his flight, they positioned to attack the enemy planes as the other flights continued on to bomb their target.  He couldn’t yet tell what the Japanese aircraft below him were, but it didn’t matter.   He wasn’t going to try to maneuver with them…..Anthony thought as he smiled and nosed the big plane over……Seabolts are just awesome in a dive.

The reality. 

The Republic XP-47H was a recipient and test bed for the Chrysler IV-2220 inverted vee 16 cylinder engine.  A latecomer to the US’s “Hyper Engine” program, it fared no better than the other designs…..even those that showed promise were rapidly overtaken by the jet engine. 

Nonetheless, it was a very interesting design, basically two V-8’s mated together.  It had commendably small frontal area but was monstrous in length at nearly 10 ½ ft.  (similar displacement Rolls Royce Griffons were only about 6ft long.)  Interestingly, power take-off for the reduction gear came from the center of the engine, as did the supercharger and accessories drives.  This substantially reduced torsional twist in the crankshaft.  Single overhead camshafts operated two valves per cylinder in a hemispherical combustion chamber.  It was the first of Chryslers “Hemi” engines.

 Unfortunately, while the airframe certainly looked potent…the long engine giving the Thunderbolt streamlining it never had before….the engine was not up to par yet.  Its power at that stage of development apparently fell short of the desired 2500hp and the aircraft only managed about 414mph.  Stock Thunderbolts could do better, and with the advent of the jet engine showing so much more promise, the Army was no longer interested.  The potential in the engine was evident, and had the jet engine failed, this may have been the shape of things to come.  What if…….


This project started out strangely.  I had a spare set of floats from a 1/48th Wings Kyofu kit and wanted to mate them to some aircraft for a whiffer build.  An Otaki Hellcat caught my eye, as did a Monogram “Bubbletop” P-47 kit in the stash.  But I had just finished a Tamiya Kyofu and felt both of those would look too similar in shape.  I wanted something different.  Then my eyes rested on the weird shape of the Koster vacuform XP-47H conversion fuselage and the little light bulb went on in my head.  That would look pretty neat, methinks.  But hey, what if I used the Medallion models P-47N resin wings also?  A long range floatplane interceptor…..hhhhmmmmm…that just sounds awesome!  So here we have a strange collection of parts all designed for the Monogram T-bolt.

 The very nice Koster vacuform XP-47H Thunderbolt conversion consists of two fuselage halves, a propeller assembly jig (a nice touch) and some 3 resin intakes and a resin propeller/spinner assembly.  All these parts are very nicely done and the resin bits exhibited no flaws or air bubbles.  One of the propeller blades had a slight bend, but that will be easily fixed with a cup of hot water.  Detail is nicely done, though the panel lines are a bit wide….normal for a vac kit and it should still look nice under a coat of paint.

The fantastic Medallion Models P-47N conversion. This consists of resin wings, wheels and bomb pylons, and white metal landing gear and propeller assembly.
  The detail is awesome….very fine engraved panel lines; very nicely done.  Too bad they are no longer in business.

The floats from a Wings48 Kyofu vac kit.

A Squadron vacuform Malcom hood.
  I have always liked the look of Malcom hoods on Thunderbolts.

Last but not least the necessary donor parts from a Monogram Thunderbolt kit, in this case a bubbletop version, but it doesn't really matter as all I will need is the cockpit and the horizontal stabs.


The first thing I had to do is cut out and sand down the vac pieces.  This really isn’t as scary as most think it is.  Here are the steps I use:

 1.  Get a sharp pencil.  Draw a line around each part on the sheet.  Use a larger X-acto knives with a curved blade (#11 blades seem too flimsy for this) and score on the outside of the pencil mark of each part, trying to keep the knife at about a 45 degree angle, angled in towards the part.

2.  Snap, don’t cut.  No need for the score to go all the way thru, as the next step is to “snap” the parts from the sheet. 

3. Next, carefully sand down all the parts to eliminate the “waste” plastic that is there.  Cutting the parts at a 45 degree angle back “into” the parts helps reduce the waste which helps reduce the amount of sand time, and anything that reduces the amount of sanding is a good thing.  This is also where the pencil mark comes into play. 

Remember,   the pencil line rules!!   Do not forget this.  Pick a suitable flat area and tape some sandpaper to it. The idea is to sand until the pencil line just disappears, but no farther.  Check the part often, check the line often.

Once I had the floats and fuselage halves sanded down, I glued small tabs on all the vac pieces to serve as alignment aids.  I then proceeded to epoxy a copious amount of lead weights in the front of each float half.  After this was dried I glued the main and outboard floats together.  I let these dry while I turned my attention to the office.  This was assembled and painted a darkish green.  I used the kit instrument decal and glued it to the panel…should look the part once the canopy is on.  I also used some Eduard seat belts to liven things up a bit.  I then mounted the cockpit in the fuselage, using some round evergreen tube as mounting posts to get the alignment right. 

Time to join the fuselage halves.  This went together well, but the front resin intake, which is sort of captured by the fuselage, wasn’t so cooperative.  I kept dropping it inside, each time managing to retrieve by a combination of special maneuvers to get the piece back out of the opening.  Once in I superglued it in place.  A few swipes with some sanding sticks and I was ready to move on. 

In the Forum I had started a Work in Progress thread, and it was at this time that I posted a pic eyeballing the float position.  Some of the members suggested that I lengthen the float…it looked too short for the Seabolts fuselage.  I agreed but was apprehensive…I had never done any surgery of that type before and was nervous about screwing up the only float I had.  They responded with suggestions and mucho support, so I gave it a try.  I cut the assembled float in half and extended it about six scale feet….1 ¼” or so.  Using the keel as my straightedge I wrapped Evergreen sheet around it and got out the putty and sanding sticks.  When done the “new” float looked much better; much more proportional to the length of the fuselage.  I was happy.

I “took a break” in between float sanding sessions and turned my attention towards the resin wings.  My next step was to cover up those gorgeous wheel wells…this craft is not going to need them.  In keeping with the “long range” theme, I declared it would be more space for fuel.  I used the Monogram kits landing gear doors to cover the bays….with just a little sanding and some Evergreen tube for them to sit on, they fit very well.  I then puttied and sanded the area smooth, then scribed some new panel lines.  Presto….no more wheel wells.

Next on the agenda was to glue the wings and stabilizers to the fuselage and putty and sand things smooth.  Considering both these conversions were meant for the same Monogram kit, the fit was actually pretty good.  I still had to putty and sand, but that’s what we live for, right?!?!

Okay, time to join the craft with the main float.  Here I glued some brass rod, for structural strength, into the fuselage and down into the main float…..I really didn’t want this falling apart on me.  Trying to get these parts and the two forward struts all aligned before the CA glue dried was cause for some heart palpitations for sure!!!

So here we are with a mostly complete figment of imagination.  Time for some paint!!


I settled on a navy tri-color scheme after pondering some of my own and several very interesting ideas from the forum members.  It was one of the really difficult parts of this build, trying to decide on just one.  But with scheme in mind, I went for the spray booth. 

First color down was Dark Sea Blue.   I then sprayed a darker mix around the panel lines and a lighter mix in the panel centers to kill the monotone.  Next on was Intermediate Blue (all Model master colors here) and then the white for the bottom, repeating the shading for each color.  Spraying the darker colors first makes the others look “dirtier”, which is more realistic to my eye. 

After this dried I gloss coated the model with Future and then also let this dry for a day.  Then it was time for decals.  Again a member of the forum came to my rescue and suggested the red-surround insignia to give it a splash of color.  This idea I liked and found some suitable units in the decal dungeon.  I also knew this bird was to have a scantily clad vixen on the nose…this I found in Eagle Strike's "American Jabos" #48053.   The "Raid Hot Mama" moniker is from a P-47D of the 510th FS, 405th FG.  It has always been one of my favorites....I just never got around to building, well, a "normal" P-47 in a I decided to use it here. The propeller warning stripe on the float is from Monogram's Devastator sheet...a wing chevron or some such. And the float "eyes" came from a severely used up Warhawk sheet...I saw them and thought that would look really cool floating in the water with those eyes peeking out.  These all snuggled down well with a coat of Solvaset.  Also, as a rule of thumb, any decal that has clear areas on it…i.e., that could “silver”, I add a drop of Future to the area before I lay the decal down.  It has worked so far……….

Next on the agenda was going over the panel lines with a yellow-ish white oil wash to highlight them.  And then I tried a new technique……laying down a  multi-colored oil paint “film” that I learned about in the forum to subtly change the hue of the paint.  Here you “dot” the surface with various oil colors, then you blend them in with a soft brush damp with thinner (I used Turpenoid here) till you get a slight color film.  It is hard to see in the pics, but I really like the result and will be doing this more often.  I duly gave the model a coat of Future/Tamiya flat base to dull things down, and at this stage we are ready for the final bits. 


I added a DF loop antenna I found in the stash…figured it would be needed for those long flights over the Pacific.  The canopy was attached and here I ran into a small problem.  I had some unsightly gaps on the front windscreen to deal with.  Not a fault of any part, more on my not getting the canopy cut out correctly.  No worries though,  I filled the offending gap in with white glue…it is a great gap filler for canopies due to its drying clear and self-leveling ability.  It shrinks as it dries so several applications were necessary.  I touched up the paint in this area and all looked well.  Next to go on were two 1000lb bombs that were painted and decaled, glued on to some nifty little sway braces from the stash (never throw parts away!).  I added gun barrels made from brass tubing, and that pretty much completed the beast.  Well, except for a place to sit.

Halfway thru this build I scratch built a beaching trolley for this to sit on.  This was made from Evergreen I-beam, square tube, and sheet.  It wasn’t all that difficult, as it is just straight beams, no hard curves to fabricate.  Wheels came, again, from the stash. 


I can’t really comment on this kit, ‘cause it isn’t a kit, really. 

- I can say the old Monogram Thunderbolt, bubbletop or razorback, is a still great kit that can be had real cheap

- I can say that the Koster conversion set is very well done and a great way to have something different in your collection.  The vac and resin pieces are very well molded.  I will be ordering more from Mr. Koster.

- I can say that the Medallion Models conversion set is also extremely well done.   The detail is fantastic.  Again, it is sad that they are out of business.

- I can say that I had a blast putting this concept and all these different bits together.  My love of float planes is what got this “off the ground” and it was a good excuse to try so many different things.  Kitbashing, scratchbuilding, panel line and rivet engraving, different weathering techniques….a lot of firsts for me here.  And the help and support I got from the forum members was truly fantastic.  Thanks guys!!!

I had fun.  And that’s what it’s all about.


- The web

- U.S. Experimental & Prototype Aircraft Projects: Fighters 1939-1945

 (ISBN 978-1-58007-109-3)

- Allied Aircraft piston Engines of WWII (ISBN 1-56091-655-9)

- Squadron/Signal P-47 In Action

Kits courtesy of me and my love for anything different. ( especially with floats on them!.)

Dale Rannals

June 2009


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