1/72 Republic XF-91 Thundercepter V-Tail

[TheRealMrEd]

Hello again.

 

Due to impending holidays, chances of visitors, and general laziness, I have determined to try, at least for the rest of this year, to do some simple, quick to resolve models -- I hope!

 

With that in mind, first up is the excellent Planet Models XF-91 Thundercepter V-Tail version.  Having done the radome-equipped, standard tail version a few years ago, I felt this model would meet the criteria, and be another example of a resin model build to encourage others to take the plunge!

 

The Thundercepter was designed with inverse taper wings, to help combat the early jet phenomena of "pitch-up".  You can discover all that conversation elsewhere on-line, so I won't cover it here.  A secondary reason for building this aircraft was to explore the use of dual engines-- a regular jet for normal cruise, and a rocket assist when high speed was needed.  In the end, as jet aircraft engines progressed, this need was deemed unnecessary,  as well as the logistics surrounding having to ship, store and load dual fuels for each aircraft.  Thus only two aircraft were ever built, both being used for testing.  I'd like to imagine that a lot of the research that led to our modern dual-tail aircraft was due to this V-Tailed aircraft.

 

Anyway, the box looks like this:

 

 

The aircraft itself has very few major parts, but there are a lot of small pieces for the landing gear retraction links, etc.  I will not do a kit review here, as it has been done elsewhere on-line.

 

The first step on most resin models is to complete the "innards" before closing the fuselage.  In this case, the innards consist of one large cockpit/front gear well piece, the ejection seat and backrest, control sick and instrument panel with foot pedals.  I glued them all together and painted them appropriately.  Then the cockpit assembly was glued to the right fuse half with CA, followed by a liberal dose of 560 canopy cement, which is kind of like heavy duty white glue, for insurance.  You may refer to several of my previous builds on this subject, so I won't rant here...

 

Care must be taken to assure that the intake splitter is truly vertical, and that the landing gear well lines up with the front gear door opening.  Then some weight is added under the cockpit area, using the afore-mentioned CA + extra glue method:

 

 

Above right, sorry for the blurry photo. 

 

Next, despite sanding the fuse halves flat with sandpaper on a flat surface, some filling will be required along the fuselage seams, but not a lot:

 

 

When all that sanding is sorted, the v-tail is next added, and some filling done there as well:

 

 

Planet models has thoughtfully provided a dotted line molded into the aircraft on each side to show the center-line of the wing.  This helps immensely when positioning the wings onto the fuselage eventually.  But, I had learned from the earlier model that I'd built, that this was no picnic  -- so I marked and drilled the wings and fuse, drilled tiny holes, and used short lengths of wire to correctly locate the wings later on. This serves two purposes; one, to allow me to paint the wing before assembly if desired, and two, the wing on the aircraft has variable incidence, so the seam from wing to fuse will not need to be filled, resulting in use of less cement, thus the wire will add a little additional support:

 

 

Above right, the same procedure is used for the fuel tanks, as adding them later with only glue is a real bear, at least for me.  The wire pins just make life a lot easier.

 

Next, the vacuformed canopy is carefully cut out, and glued to the fuselage with G-S watch cement:

 

 

My usual process is to smooth the excess watch cement with 91 percent alcohol, but for some reason, this time around, I could not see the clear glue well enough to see whether is was filling everything smoothly.  So, above right, I taped off the glass area of the canopy, and added some 3M spot putty, just to make sure everything was going "smoothly".  As I have stated before, I go to great lengths to prevent "steps" where jet canopies join a fuselage, unless the real aircraft also had them.

 

Well, time for putty to dry, and for me to plot my next evil deed, so more next time.

 

Ed

 

 

[Shorty84]

Hi Ed,

 

great choice. The V-tail makes the Thunderceptor look even more unusual than it already was. Planet Models kits are quite painless to build usually so I hope it remains a simple build for you.

 

Cheers

Markus

[Corsairfoxfouruncle]

Two Thunderceptors today wow ! Im definitely in for this. 

[71chally]

Great to see a Thunderceptor being built by your hands Ed, the kit is an unknown to me but looks nicely detailed.

 

This aircraft has always fascinated me, it's though Kartveli/Republic sat down and decided to build an aeroplane that deliberately bucked the norm.

Inverse taper wings is one thing, but they were also of inverse thickness (wing tips thicker than the root), and the wings was movable for pitch trim, on top of that the undercarriage retracted out into the wingtips - brilliant

[John R]

For gettingthe wings to line up and provide matching dihedral or anhedral I join the wing halves to the fuselage before joining the fuselage halves. By putting each half fuselage flat on the bench and mounting the wing on top of it and then lining them up by eye, using a template or a protractor you can get the halves to match. ( though a bit late for this build)

John

[Lightningboy2000]

Excellent work so far.

Just wondering how similar that fuselage is to a standard Thunderjet? Looks very similar. That wing design is really wacky as well!

 

Martin

[TheRealMrEd]

Thanks for looking in folks.  Hi John R, that sounds like a good plan.  Sometimes I do add the wings before joining the fuse halves, but not often.  I never do when doing a bare-metal, two-engined aircraft, such as a B-45 or a B-25, as I find that the blast of the airbrush, even when turned, caused the primer to swirl and not be smooth between the nacelles and the fuselage, thus screwing up the BMF.  Here, there's a bit of tricky masking to be done in the wing area, so it wouldn't do either.

 

Lightningboy2000, I'll try and remember to add a comparison photo at the end.  Interesting handle, that.  Is there a backstory?  Just so happens that my wife, myself and our oldest daughter were struck by lightning in 2004...

 

Anyway, after sanding the fuselage/canopy join to what I think is  smooth, and then cleaning up some of the fuselage lines with a pin in a vise, the canopy  was masked.  This time, I decided to try a different -- at least for me -- approach, that of masking using tiny bits of tape along various edges:

 

 

It seemed to work alright, 'though a bit tedious.  I did it because the canopy has a few tiny little shapes here and there, which would have meant a lot of fine trimming if I'd gone with my more usual method of Parafilm "M".

 

Next up, a bit of the rear plumbing has been added, necessitating more  filling, sanding, etc.:

 

 

Above right, the actual aircraft has rather prominent lights on the tips of the two stabilizers  (what do you call them when they're neither vertical nor horizontal?).  Being at the rear of the aircraft, one can assume they're either white or clear bulbs.  I'll go with the clear.  For the benefit of our newer modelers who don't already know the technique, here's how I did it.  (More experienced modelers can just fast forward here!

 

First off, a piece of clear small parts drawer divide plastic is sawed off with a razor saw, although Lucite or clear sprue or whatever can be used:

 

 

Next, above right,  a tiny drill in a pin vise (I used a #78 here) is used to drill two tiny holes in the sawn off part or the previously shown sawn off piece.  This piece will then be cut in half again, leaving one drill hole in each part.  Each part will then be glued to it's respective stabilizer with CA.  If the model had been made of plastic rather than resin, I would have just used regular thin liquid plastic cement.  If these parts were to be added to wingtips, each little bulb hole would be filled with, either red, blue, or green, as warranted.  Since the bulbs in the photo appear clear, I will not add and paint to the holes in this case.  In other circumstances, I might add a drop of white paint in each.

 

I tried to take pictures of each stage of this process, but I must have been shakier than usual when I took the pics, as some, like the one below are blurry, and some were so bad I couldn't even use them, but I had moved along in the process of model-building, and it was too late to take more pictures.  I'll take some better ones later on, so that the finished result can be seen:

 

 

The next step (where the photos didn't turn out) was to simply sand down, then polish, the clear lenses to a suitable finish.  In my case they have already been masked with Parafilm "M" and then the other areas of the stabilizers that are to be painted red, was masked off, then painted with white primer:

 

 

Above right, the nose was also masked off, as were the wingtips (not shown).

 

Well it off to the paint shop.  Back later,

 

Ed

 

 

[TheRealMrEd]

Well, back from the paint shop.  First off, red wingtips, etc. were given a coat of white primer, followed by Insignia Red FS31136.  The anti-glare areas,  including the canopy frames, were masked off and sprayed with FS34092, the color that is now known as Euro Dark Green, which Republic seemed to favor. When that had dried all the red and green parts were masked off with Parafilm "M" and all the unpainted parts were painted with Alclad II Black Primer. When dry, a coat of Krylon Gloss Black enamel will be applied:

 

 

Above right, after drying, the black enameled areas were all given a coat of Alclad II Polished Aluminum, after which, some areas were masked off with Parafilm "M" and a couple of other metallic colors were sprayed.  The red and green areas remain masked off.

 

Below, some of the masking is removed, and the wings are stuck on temporarily:

 

 

Above right, some of the decals are installed.  Note that the kit supplies decals for the lower wing that are already cut apart for the various gear doors.  This makes life much more simple, as all you have to do is temporarily install all the gear doors, and carefully apply each decal to it's correct place.  The kit's instructions show where these go.  The red strip and the needed red "no walk" area decals on top of the wings are not provided, so here the spares box is called upon.

 

Next, all masking is removed and the wings are CA'd in place from underneath; all the decals have been installed:

 

 

Now comes a little detail painting, and assembly of all the small parts, like landing gear and doors, pitot, etc.

 

Back soon!

 

Ed

 

 

 

 

[LorenSharp]

Looking good there! Nice bare metal paint job. The end is in sight

[billn53]

This is looking just SUPER!

[Alan P]

Beautiful job Ed! An unusual and challenging subject but you nailed it.

[TheRealMrEd]

Thanks folks!

 

However, "nailed it" is a bit premature...

 

We now come to the hands-down hardest part of this build -- the landing gear.  It is an unusual affair to being with two wheels on either side, but in trail.  That is, the rear wheel is supposed to "trail" in the path of the front wheel:

 

 

Sorry about the size -- thought I'd shrunk it further...  Anyway, above right, the kit asks you to glue two parts #27 to one part #20, with the axles each facing inward.  There is hardly any gluing surface at all, and the directions (and logical observation) differ, in that one would expect to glue the parts #27 to the sides of part #$20.  Not so, they must go on the extreme lower end, which I shall attempt to show with rather poor pictures.

 

In the photo below, they parts #27 get glued where the line is, NOT where the arrow is:

 

In the photo above right, they are glued where the arrow points, NOT in the area marked "X".  Also, note that "A" and "B" denotes the fact that each axle points in, toward the center.  An addition, the "axles" must be shortened, to allow the wheels to line up in trail.  In addition, the two parts #27 must be put on at the correct angle, to allow the two wheels not to touch, but if set too far apart, the wheels will not set level.  Beyond a doubt, THIS is the hardest part of the kit!

 

Below, "A" shows the shortened axles, vs the kit length, marked "B":

 

 

Above right, the wheels are almost in trail, but not quite.  In addition, either the hole in the wheel must be drilled larger, or the "axles" must be sanded thinner.  I have done four of the leg assemblies, on two different kits, and none of them have come out exactly right for me.  Perhaps you'll have better luck!

 

One other problem, which was not apparent at first, at least to me, is that left uncorrected, the two gear legs will toe out, vs straight in-line, fore-and-aft.  This would require mild sanding to the gear leg, where it mount to the wing, to allow the gear to angle inward a bit.  See below pics:

 

 

It should be noted that there are no positive locators on any of these parts, so every problem is three-dimensional!.. That being said, short of casting metal legs, I doubt that I could have designed any of this any better.  It's not a knock on the kit maker, just an issue brought on by the weird design of the actual aircraft.  Oops, looks like I'll have to straighten the right gear leg a tad, vertically!

 

Well, enough for now.  Time to go have a strong beverage, and bemoan the fact that the modeling gods have abandoned me.  See you when I recover...

 

Ed

 

 

[Jackson Duvalier]

Nice work as usual, Ed.  I really admire your ability to simply get on with things. 

[Space Ranger]

That is without a doubt the strangest landing gear I have ever seen. Even if it did have to fit in a thin wing, I'd like to know the designer's rationale for coming up with something so weird. Was he on drugs?

[TheRealMrEd]

Well, I finished tidying up a few bits here and there.  The main landing gear leg doors were glued to the legs with 560 canopy cement, which dries clear.  I used this slower-setting glue because I could prop the model on it's side while each set of doors dried.  The outer doors were added to the wings with G-S watch cement, because it also dries clear, but sets faster.  After turning the model upside down, I was able to block up the outer gear doors to hold the desired angle.

 

At first, I thought the pitot boom was striped, but closer examination of photos revealed that it was barber-pole striped.  So, I after painting the boom gloss white, I wrapped a very fine length of Tamiya tape around the boom in a spiral fashion, then painted the whole thing red, after which they tape was removed.  The resulting striping is not perfect, but certainly better that I could have done free hand!

 

Anyway, the beast is finally done.  As a teaser photo, I will provide the comparison shot promised earlier, of the F-84F and the XF-91.  As you can see, that while the XF-91 fuselage is much larger, there is a certain "family" resemblance:

 

 

In a few minutes, I will add a few more pics over on RFI  HERE

 

Thanks for looking.

 

Ed

Edited November 27, 2020 by TheRealMrEd
added RFI link

[Corsairfoxfouruncle]

Well done sir Well done.  ... Those landing gear give ne nightmares and I didn't even build the kit. 

[Dennis_C]

2 hours ago, TheRealMrEd said:

As a teaser photo, I will provide the comparison shot promised earlier, of the F-84F and the XF-91. 

Wow! Great build and excellent comparison photo! XF-91 was not a small boy by any means