BTE Reaction 54 Instruction Manual

INSTRUCTION BOOK

FUSELAGE CONSTRUCTION
18
WING AND TAIL MOUNTING
21
FLYING TIPS
34
PRE-FLIGHT SETUP
33
TAIL PUSHRODS
23
FINISHING THE FUSELAGE
25
FUEL SYSTEM INSTALLATION
28
30
TURBINE INSTALLATION
31
RETRACT INSTALLATION
RADIO INSTALLATION
32
INTRODUCTION
2
RECOMMENDED EQUIPMENT
35
WING SUBASSEMBLIES
5
WING PANELS
7
WING PANEL DETAILS
11
JOINING THE WING PANELS
13
TAIL SURFACES
14
FUSELAGE SUBASSEMBLIES
16
OPTIONAL ACCESSORIES
37
COMPLETE PARTS LIST
39
2-VIEW DRAWING AND SPECS
38
Proudly Manufactured in the USA by
BRUCE THARPE ENGINEERING
8622 E EVANS CREEK ROAD
ROGUE RIVER, OR 97537
Information: 541-582-1708
Orders: 800-557-4470
www.btemodels.com
Questions? Call BTE or email
[e-mail]
WRITTEN BY BRUCE THARPE
BUILDING INSTRUCTIONS FOR THE
Instruction Book Version 5

Thank you for selecting the Reaction 54 kit from BTE! The R54 is an entry-level R/C turbine model
utilizing traditional wood construction. A lot of effort has gone into the engineering of this kit to make
it an enjoyable and satisfying project from the first drop of glue to the first landing. It has always been
a goal of BTE to produce kits that are just as pleasurable to build as they are to fly.
Welcome
If you are new to turbines, welcome to the pinnacle of recreational R/C modeling. You have no doubt worked your
way up from trainers to sport models to aerobatic ships. Perhaps you've gained some quality stick time with racers or
ducted fan models as well. Those are all cool in their own way, but in my opinion at least, there is nothing like the thrill
of piloting a model propelled by the raw power of a miniature
gas turbine. There is something very pure about a turbine
model in flight. The lack of torque and general aerodynamic
cleanliness combine to produce a smooth, almost silky,
performance. And oh, that sound! When you taxi onto the
runway and move the throttle stick forward, you know
something special is about to happen. We're talking serious
goosebumps.
If you are an experienced jet pilot, you will find the R54 is a
refreshing and relaxing alternative to the high-buck, high-
maintenance, high-stress turbine models that you may be used
to. It will probably be your slowest turbine model, but if the
R54 fills the roll of your "everyday" jet, then I will consider that
a success. Sometimes it's not about the speed, it's about the
spirit.
My Background
I came to the world of turbines in a different fashion than most. My
previous jet experience came from designing, building, and flying
sport R/C models powered by pulsejet engines. My father
introduced me to the famous Dyna-Jet Redhead many years ago,
and they have always held a certain fascination with me. Anyone
who has heard the incredible roar of a Dyna-Jet never forgets it!
As you may know, pulsejets are incredibly loud, run very hot, have
no throttle, and can be temperamental. Oh, did I mention they are incredibly loud? Every landing with a pulsejet
model is deadstick, so most of my designs featured big wings so they would glide well. Speed was never a priority. In
fact, efforts were made to keep the speed down because I prefer close-in flying. This design philosophy, to a certain
extent, was translated to my first turbine model, the R54.
About the Reaction 54 Design
My father and I built a number of pulsejet models dating back to the 1990’s. One of those models, our Old Flame, was
perhaps the best pure flyer of the bunch. The overall configuration of the R54 borrows heavily from the Old Flame in
that it features a low wing with the engine mounted under the rear part of the fuselage. On the next page is a list of
the other major design considerations for the R54...
The Moment of Truth! Bruce's sister, Susan, poses
with the prototype Reaction 54 moments before its
maiden flight at the Siskyou County Airport in northern
California. Look close and you can see the faint
outline of Mount Shasta in the background.
The inspiration for the general configuration of the
Reaction 54 goes back to this Dyna-Jet powered
model, the Old Flame.
2

All Wood - I'm comfortable with traditional wood design, and I figure so are a lot of potential modelers looking to get
into jets. Besides, being all-wood helps it stand out in the jet market that is dominated by composite designs.
Big and Light - Big models are easy to see, and light models are delightful to fly. Bigness helps keep the top speed
down, and lightness helps keep the landing speed down. A big fuselage gives you plenty of room for all that "stuff"
that turbine models need to haul around. A big, thick wing is inherently strong and gives you plenty of room for
retracts. Light weight gives you vertical performance and reduces landing gear loads.
Retracts - In my opinion, there has been a tendency to make entry-level turbine models too simple. Aspiring turbine
pilots have above-average skills and don't need to step back to a basic trainer. The R54 is still a fairly simple design,
but I want it to serve modelers well as a stepping stone to faster, more-complex turbine models. Retracts are part of
the jet scene, and the R54 just wouldn't look right without them.
Exposed Engine - I saved my pennies for several years to buy my first turbine engine, and didn't want to bury it inside
an airframe. Besides, an exposed engine is easy to work on and saves the weight, cost, and complexity of an exhaust
tube, inlets, and bypass. The R54 features an elegant streamlined area just ahead of the engine to help maintain
smooth airflow to the turbine inlet. For lack of a better term, I call this the "boat tail".
Low Cost - By definition, a turbine model will be expensive compared to most R/C models. Besides the engine itself,
the typical turbine model is expected to have custom-made composite fuel tanks, spring-loaded landing gear struts,
and special machined "jet" wheels. A major goal of the R54 was to keep the total cost low compared to other turbine
designs by using low-cost, off-the-shelf hardware items like the Du-Bro fuel tank, wire struts, and regular wheels. The
R54 blurs the line between your everyday sport model and what has become the norm in the turbine community.
Safety - The greatest safety feature of the R54 is that it's fairly slow by turbine standards and easy to fly. Care was
taken in the design to separate the fuel tank area from the turbine with a robust structure in the boat tail. A neoprene
pad is provided to cushion the front of the tank in an impact. The BTE prototype model has been thoroughly flight
tested and has proven itself to be a robust, well-behaved design that does what it is supposed to do, and does it well.
Things You Don't Normally See on Turbine Models
There are some design and equipment aspects of the R54 that you don't normally see on the typical turbine model.
To put your mind at ease, here is the reasoning behind some of my choices made during the development of the R54.
Push/Pull Cable Linkage for Rudder and Elevator - This might be the most unusual aspect of the design, but it has
proven itself in flight testing and on several of my earlier pulsejet designs. When installed as shown on the plans, you
will find the system makes for a very rigid, slop-free connection to the control surfaces. The servos are mounted up
front to keep the weight forward and are easy to access under the large hatch.
Easy Hinges - I love these hinges! They are economical and easy to install. Some might question their strength, but
that is addressed by using lots of them spaced fairly close together. If you go with plastic film, you don't even have to
worry about hinging until the model is completely covered.
Wire Landing Gear Struts - These aren't included in the kit, but they are supplied with the recommended retract
package. The struts on the R54 are short, so 3/16" wire is plenty stiff to handle the loads, even on grass. The R54
lands slow, so it doesn't need the cushioning of more expensive oleo-style spring struts.
INTRODUCTION, continued...
3

Sport Wheels - A low-speed model like this doesn't need special, high-priced "jet" wheels. The 3" diameter Sullivan
and Hangar 9 sport wheels that I use handle rough terrain with no problem and the tires have never rolled off the rim
even after some bad landings with high side loads. And they are cheap to replace if necessary.
Electric Nose Wheel Brake - AMA requires brakes on turbine models. Again, considering the low-speed nature of
the R54, brakes aren't really necessary. The Kavan electromagnetic brake meets the AMA requirement, is relatively
inexpensive, is easy to install, and adds a little weight to the nose which you need anyway.
Bolt-On Wing - Modelers who have built my designs in the past know that I like to keep things simple. That's why the
R54 has a simple one-piece wing that bolts on like a normal sport model. This provides a solid center wing joint
without the extra complexity, weight, and cost of wing joiners. Besides, the finished wing is shorter than the fuselage,
so transporting is not a big issue.
Open Rib Bays - To drive home the sport model feel of this design, I went with some open rib bays near the tips. I've
seen film used on open structures on birds much faster than the R54. You can sheet the whole wing if you wish
(plenty of wood is provided in the kit), but in my opinion it's just extra weight.
Plastic Film Covering - Okay, this isn't totally uncommon on sport jets. Still, the R54 was designed with plastic film
covering in mind from the outset. Use a high-quality film like Monokote or Ultracoat, and be mindful of the orientation
of the seams in relation to the airflow.
Glues
General construction of most of the model can be done using Cyanoacrylate Adhesive (referred to as CA in the book).
BTE offers a package of high-quality Handibond CA tailored specifically to the R54. The instructions will, from time to
time, make suggestions as to the type of glue to use in certain steps. There are times when a good aliphatic resin like
Elmer's Wood Glue or Tite-Bond (referred to as "yellow glue" in the book) will be the best choice. Slow-dry epoxy (30-
minute or longer) is recommended for high-stress areas like the wing joint.
A Note About Craftsmanship
I keep referring to the sport nature of this model and my effort to keep it simple. Do not, however, lose sight of the fact
that this IS a turbine-powered model that can achieve high speeds and high in-flight air loads. I encourage you to take
your time with the construction, build it straight, and build it strong. Every effort has been made at BTE to produce
wood parts that fit well, but ultimately, the quality of the finished product is up to you. Approach the building process
with an attitude of "do it right" rather than "do it fast", and you will be rewarded with a unique R/C model that you can
truly be proud of.
Enough Already, Let's Build!
Okay, okay, but like all instruction book writers,
I am obliged to insist that you read through the
booklet completely before you start, and study
the plan sheets. Think ahead. Grab the glue.
Turn the page... R54
INTRODUCTION, continued...
4
LIMIT OF LIABILITY
In use of our products, Bruce Tharpe Engineering's only obligation shall
be to replace such quantity of the product proven to be defective. User
shall determine the suitability of the product for his or her intended use
and shall assume all risk and liability in connection therewith.
Instruction Book Note for 2014
This book was originally written about ten years ago, and there have
been some major advancements in the hobby and turbine engines
since that time. We now have 2.4GHz radios, kero-start turbines,
electric retracts, and numerous other advances in equipment. But
balsa is still balsa and the science of aerodynamics remains
unchanged. So build your R54 as shown - there have been no
significant changes to the airframe since it was introduced. In later
chapters, you will see references to dated equipment, but the
examples presented there and your own experience should be
enough to guide you through. As mentioned at the left, think ahead!

Once these time-consuming tasks are done, you'll be ready to fly through the assembly of the wing
panels with minimal delay. Let's roll...
 Optional - If you plan on building your R54 with open rib bays, skip to the next step. If you plan on sheeting
your entire wing, you need to trim the W-13 wing ribs as shown on the plan.
Later, capstrip material will be added to the recessed edges to provide extra
gluing area where the center sheeting meets the wingtip sheeting.
 Glue a W-6D doubler to each side of both W-6 wing ribs. When dry,
cut away the exposed balsa as shown in the photo.
 Cut out the Wheel Well Template (blue card stock) and use it to
mark the W-4 and W-5 wing ribs. Go ahead and cut the ribs along the upper
line, but only score the vertical lines for now. You will cut those later, after
the ribs are firmly glued into the wing structure.
 Using the short notches as guides, mark the position of the dihedral
brace slots on the W-1, W-2, and W-3 wing ribs. Again, don't cut them yet -
the lines will help guide the cuts later when it's time to join the wing panels.
 You can tell the bottom main spars from the tops because the
bottom spars are beveled slightly on the front edge. The purpose of the
beveled edge is to provide a flat gluing surface for the shear webs. Locate
the two bottom main spars and the two 12" spruce bottom spar doublers.
Taper the outboard ends of the spar doublers as shown on the plans. Be
careful here - you need to make a left and a right! Glue the doublers to the
main spars, being sure to align the beveled edges.
 Repeat the previous step for the top main spars. The top spars are
not beveled, so there is no need to worry about making a right or left.
 Mark the two remaining 36" spruce sticks 19-1/2" from the end, and
cut them at the mark. The 19-1/2" sticks will be the bottom stub spars, and
the leftover 16-1/2" sticks will be the top stub spars.
 The wing trailing edge is made up of two machined balsa sticks that
overlap near the center of the wing. Taper the end of the inboard TE stick
as shown on the plans, then glue it to the outboard stick using the plans as
a guide. Be sure to make a left and a right.
 Make cutouts in the flap servo mounts and the aileron servo mounts
to suit your servos. Use the dimensions shown in the photo to position the
outboard, forward corner of the cutout. Cut 2"-long reinforcing strips from
the 1/8" x 3/8" x 12" lite-ply strips in the kit, and add them to the front and
rear edges of each cutout. Again, make lefts and rights.
Cutout
Balsa
W-6D
Cut Here Only
1/2" 3"
4
Main Spar Assemblies
Right-Hand Trailing
Edge
Left-Hand
Trailing Edge
Flap
Servo
Mounts
Finished Mount
5

 Separate the lite-ply
wheel well floors from the wheel
well frames using a scroll saw or
hobby knife to cut at the dotted
lines shown in the photo at left.
 The lite-ply shear web at
the wing root is also used as a
dihedral gauge during wing
construction. To avoid any
confusion, mark the shear web
as shown in the diagram.
 A 1" x 3" x 4" chunk of
balsa is provided as material for
the wing bolt support blocks.
Use the shear web from the previous step as a template to mark the
proper shape of the support block as shown in the photo. Cut the block
into two pieces, and discard the scrap.
 Glue the balsa dowel support blocks to the lite-ply dowel block
doublers. Line up the aft edges of each part.
 Locate the six pieces of 3/32" x 3" x 36" balsa, then select the
two lightest, softest pieces to use as shear web material. The remaining
four pieces can be set aside to use as trailing edge sheets.
 Inspect the 18 sheets of 3/32" x 4" x 36" balsa
supplied in your kit and select eight pieces to use for leading
edge sheeting. Look for medium weight, long-grained sheets
that bend uniformly. Assemble four sets of LE sheets. Trim
the edges, then glue with yellow glue or thin CA.
 The remaining ten sheets are used for center sheeting. Assemble two big sheets as shown below, then cut
them in half to make four center sheets. If you are going with open rib bays, cut the sheets first to a length of 23".
 Finally, make two sets of wingtip sheets from 3/32" x 4" x 7-1/2" balsa. R54
Leading Edge Sheeting - Make 4 from
3/32" x 4" x 36" Balsa - 2 Sheets, Edge Glued
Wheel Well
Frame
Wheel
Well Floor
Scrap
W-1W-2
TOP
LITE-PLY SHEAR WEB
87º 90º
WING SUBASSEMBLIES, continued...
Make 2
Wingtip Sheets
Make 2 from 3/32" x 4" x 23" Balsa
Center Sheeting (Open Rib Bays)
3"
4
Cut Here
Center Sheeting (Fully-Sheeted Wing)
Make 2 from 3/32" x 4" x 36" Balsa - 5 Sheets
NOTE: All Sheeting Diagrams are Not to Scale
Cut Here
6
2"
Scrap

It cannot be stressed highly enough that a flat building board is essential to building a warp-free wing.
If you haven't done it lately, take the time to check your board with a long straight edge and make any
tweaks that may be needed to make it perfectly flat. It's time well spent!
 Start by pinning the bottom main spar assembly to the
plan with the beveled edge facing forward. Use five ribs (W-2,W-
5, W-8, W-11, and W-13) as guides to position the bottom stub
spar (1/4" x 1/2" x 19-1/2" spruce), the bottom rear spar (3/16" x
3/8" x 36" balsa), and the trailing edge assembly. Don't worry if
you have any discrepancies with the plans - trust the parts! Pin
the spars and TE firmly in place, then remove the ribs.
 Glue in the plywood retract mount and the lite-ply wheel well frame.
 Add two plywood retract mount doublers. Make sure they are glued
well to the spars.
 Glue in wing ribs W-2 through W-7. Use a triangle or the 90º corner
of the lite-ply shear web to make certain all of the ribs are perpendicular to
the building board. Note: You will save yourself trouble later if you keep
glue away from the area near the dihedral brace slots.
 Install the servo lead tubes. The front tube is rolled from a full
sheet of 8-1/2" x 14" paper. For the rear tube, cut a piece of paper to
8-1/2" x 6-3/8". Use medium CA to glue the tubes to the ribs.
 Glue in ribs W-8 through W-14.
Ribs W-2 through W-14 are now in place. I like to use thin CA during initial
construction when there is a tight fit between the parts. Later on, all of the
wood joints will be given a second coat using medium CA.
7
About The Wing Design
One of the design goals of the R54 was to
be able to fly into and out of a short field,
like we have at my local club. That
requires a light wing loading, which
means lots of wing area! The airfoil is a
very unscientific shape I've used on many
sport models in the past, which puts a
priority on building ease over pure
aerodynamic efficiency. The flat portion
on the bottom helps keep things straight
and simplifies the retract installation. In
flight, the airfoil is close enough to
symmetrical that it flies through outside
maneuvers as easily as inside.
Align Corners

 Glue in the root rib, W-1, this time using the 87º corner of
the shear web/dihedral gauge. Slide the dihedral gauge back and
forth as you glue to make sure the W-1 rib is angled properly along
its entire length.
 Add the top main spar assembly, the top stub spar, and the
top rear spar to the ribs. Be sure to check the angle of W-1 to make
sure it hasn't shifted.
 Glue the quarter-round balsa leading edge to all the ribs.
Once again, use the dihedral gauge to check W-1.
 Go ahead and glue the lite-ply shear web/dihedral gauge in its place between W-1 and W-2. Thick CA works
well for this; apply it to the shear web where it will contact the spars and push it in place. Don't worry about gluing the
sides of the webs to the ribs right now; it will be easier to do later when the wing is lifted from the building board.
 Add 3/32" balsa shear webs to the front spars (nine places) and the stub spars (four places). Remember, the
balsa grain must be vertical. One sheet of balsa should provide plenty of shear web material for one wing panel. I
suggest you trim the balsa sheet (selected earlier) to a width of 2-29/32", then slice off webs for the wider rib bays.
Once those are done, you can trim the remaining balsa to fit the narrower rib bays. Note: The shear web between
ribs W-7 and W-8 needs a 1-1/4" diameter hole to pass servo wires and air lines.
 Locate the 3/4" balsa triangle material provided in the kit,
and cut four pieces 1-7/8" long. These braces are meant to
reinforce the joint between the W-6Ds and the retract mount
doublers. In a perfect world, the retract mount doublers would be
perfectly even with the spars, but in real life they are probably
slightly off. Take the time to notch the ends of the triangle braces
for a perfect fit, then glue them firmly in place.
 Glue in the lite-ply hatch rail, the aileron servo mount, and
the flap servo mount. These items should all be pushed firmly
against the board so they are flush with the bottom of the ribs.
 The balsa wing bolt block needs some final trimming before installation. Trial fit the block between W-1 and
W-2 (you will have to spread the top of the ribs apart so it will fit). Carefully mark the contour of the ribs on each end
of the block, remove the block, then draw lines on the front and back of the block connecting the lines on the side.
Now use a band saw, scroll saw, coping
saw, or razor saw to hack away the top
of the block, using the lines as a guide.
It is critical that this block bridges the
space between the top and bottom wing
skins to prevent crushing when the wing
is bolted to the fuselage. When you are
satisfied with the shape of the block,
glue it in place.
WING PANELS, continued...
8

 Select one of the leading edge sheets you assembled earlier, and trim it to fit. Start at the wingtip end, cutting
away a wedge that matches the angle of W-14. Now, hold the rear edge of the sheet flush with the rear edge of the
spar, mark the sheet at each end where it contacts the LE,
and make the cut using the marks as a guide. Finally, trim
the rear edge of the sheet so it will overlap halfway (1/4")
onto the main spar. Glue the LE sheeting in place and
allow to dry (see sidebar for details on a good method).
 Optional: If you are building a fully-
sheeted wing, add a 3/32" x 3/8" capstrip to
the top of rib W-13.
 Trim a piece of wingtip sheeting to fit
and glue it in place. Thick CA works well for
this step. You will need a tiny scrap of 3/32"
balsa to finish off the rear, inboard edge of
the sheeting.
 Prepare a piece of 3/32" x 3" x 36"
balsa to be used for trailing edge sheeting by
roughly trimming it to shape, then glue it in
place. Use yellow glue on the tops of the ribs
and thick CA along the rear spar and TE.
The sheeting should overlap 1/4" onto the
rear spar, leaving about 1/8" of the spar
exposed.
 Add 3/32" x 3/8" balsa capstrips to
ribs W-10, W-11, and W-12 (skip this step if
you are building a fully-sheeted wing).
 Even though there is no photo, this is a critical step. Remove the wing from your building board and go over
every glue joint with medium CA. That means every joint on both sides, if possible. I like to use just enough glue so
you can see a small fillet formed between the parts. Use accelerator sparingly; it weakens the cured strength of CA.
First Cut Second Cut Final Cut
Bruce's Method of Gluing on Leading Edge Sheeting
Adding LE sheeting to a wing is always a stressful step for me, probably
because I've botched it badly on previous models. The wood always seems
to be fighting me! Over the years I've settled on a method that works
pretty well and I'd like to share it with you.
1. Prepare your tools. I use yellow glue, thick
CA, medium CA with a long applicator, and CA
accelerator.
2. Prepare your sheeting. The sheeting needs to
be trimmed accurately along the front and rear
edge. The front edge needs to fit solidly with the
LE along its entire length.
3. Apply yellow glue to the top of the ribs. I like
yellow glue for this step because it dries slowly
and gives you time to perform the next step.
4. Push the sheet against the LE and apply
medium CA to the joint from underneath. This is
where the long spout helps.
5. Apply accelerator to the LE joint from above.
Avoid getting any spray on the spar, because you
don't want accelerator residue there when you
apply CA. The idea is to permanently glue the
sheet along the front edge so it can be lowered
onto the ribs with no worry of it popping up.
6. Apply thick CA to the spar where the sheet will
make contact.
7. Lower the sheet onto the ribs, and stroke it
from the LE towards the spar in an attempt to pull
it tight against the ribs.
8. Continue stroking the sheet until the thick CA
begins to grip. Press the sheet down against the
spar firmly, using accelerator if necessary.
9. Now the sheet is attached at the front and rear, but the yellow glue is still
drying. Use lots of weights like the shot-filled bean bags shown here to hold the
sheeting against the ribs while it dries. Be sure the wing is pinned down firmly so
the weights don't distort the structure.
WING PANELS, continued...
9

 Block sand any irregularities off the bottom of the wing, then pin it upside-down to the building board. Pin it
firmly at the trailing edge so the TE sheeting is flat against the building board. The front portion of the wing needs to
be supported near the main spar. I suggest using two pieces of 1/4" balsa sheet (provided in the kit). Stack the
sheets then slide them rearward until they contact the balsa LE sheeting. The idea is to support the wing without
causing any twists or distortions. Pin the supports in place so they won't
shift around later.
 Use thick CA to glue the wing dowel support assembly in place.
 Add LE sheeting, wingtip sheeting, TE sheeting, and capstrips to
the bottom of the wing just as you did for the top of the wing.
 Carefully trim the bottom center sheeting to fit snugly between the
LE and TE sheeting. Temporarily tape the center sheeting in place, then
remove the wing from the building board. Working from the top, mark the
outline of the hatch opening, the flap servo opening, and the aileron servo
opening. Also mark the retract mount area (don't worry about the wheel well
- you will cut it out later). Remove the center sheeting.
 Let's start with the servo cutouts. The actual cutouts in the sheeting
need to extend an extra 1/4" at both the front and the back to make room for
the servo mounting flanges. Ultimately, the servos must sit on the lite-ply
mounts, not the balsa sheeting. Draw the extended outlines on the sheeting,
then neatly make the cutouts.
 The wing hatch is actually larger than the opening that's drawn on
the sheeting. Carefully draw a hatch outline that is 3/8" wider on each side
and 1/4" wider at the rear. The front edge of the hatch is the front edge of
the sheeting, so no cut is required there. Cut the hatch out carefully,
keeping in mind that the cutout is not scrap - it will be used later as the
hatch cover.
 Cut the retract mount area away using the lines that are
on the sheeting. Place the sheeting back on the wing and use
an actual retract unit (or the paper template included with the
kit) to mark the cutout area for the mounting flanges. Position
the retract with the mounting holes equally spaced on either
side of W-6. Remove the sheeting, then make the cutouts so
that there will be about 1/32" clearance all around the mounting
flanges.
 Trial fit the center sheeting one last time, and mark the wing
structure through the cutouts you just made. The marked areas will indicate
"no-glue" zones. Remove the sheeting, then apply yellow glue to the wing
structure, being careful to avoid the no-glue zones. Put the sheeting in
place, then weight down the wing on your building board (use wax paper!)
right-side up so that the center sheeting is flat against the board. R54
3"
8
1"
4
1"
4
Cut
Here
Cut
Here
Wing Bottom Center Sheeting
WING PANELS, continued...
10
1/4” Sheets
for Support

At this point, the primary structures of the wing panels are complete. The last major part, the top center
sheeting, will be added after the wing panels are joined (this allows easy access to the dihedral braces so
you can be certain they are glued properly). This section wraps up some of the detail work on the wing
panels that is easier to do before the panels are joined.
 Trim the wing sheeting and spars at each end of the wing panel,
flush with ribs W-1 and W-14. It's critical to sand the root end accurately
so the panels will make firm contact with each other when joined. I made
myself an oversized sanding block just for this purpose using scrap
plywood, an aluminum bar, and a cut up sanding belt.
 Trim the TE sheeting flush with the trailing edge. Maintain the
bevel in the inboard section of the wing panel.
 Now you can finally cut the wheel opening and the wheel wells
away from W-4 and W-5 along the vertical lines you drew earlier.
 Dry assemble the 1/32" plywood wheel well liner and the lite-ply
wheel well floor in the wing. The liner can be overlapped in the area cutout
for the strut, or you can trim the liner for a butt joint - your choice. When
satisfied with the fit and position of the parts, glue everything in place with
medium CA.
 Use a sanding drum in a Dremel tool to make a rounded notch in
the liner to clear the wheel strut. Make a smaller notch in the retract mount
to clear the brass nipple on the side of the Robart retract unit.
 Accurately place your retract unit in the wing and mark the position
of the mounting holes on the plywood mount. Remove the unit, then drill
the holes carefully for blind nuts. Install the retract mounting blind nuts and
fix them in place with medium CA. Note 1: Hardware for retract mounting
is not provided in the R54 kit, but it IS provided in the optional Retract
Package available from BTE. Note 2: If you do not have your retract units
at this time, you can still do this step using the Robart Bolt Pattern
Template provided in the kit.
 Glue the wingtip trailing edge extension to the wing, using the
plans as a guide for proper placement. When dry, trim the end to match
the angle of rib W-14.
 The balsa wingtip block is roughly cut to match the wing top view.
Mark the airfoil shape on the block using the actual wing as a pattern, then
saw the block to a rough airfoil shape. Glue the wingtip block in place with
yellow glue using pins and tape to hold it in position until dry.
11

 Carve and sand the wingtip to a pleasing round shape.
You can protect the surrounding sheeting by masking off a portion
of your sanding block with paper and tape.
 The wing hatches that you cut out earlier need to be
stiffened with a balsa doubler. Use some scrap 3/32" balsa cut
slightly smaller
than the hatch
opening which is
already drawn on
the hatch. Make
sure the grain of
the doubler runs
fore and aft,
perpendicular to
the hatch grain.
Glue the doubler
to the hatch.
 Lightly sand the edges of the hatch, just enough to provide
some clearance for covering material. Mark the positions of the six
mounting holes, tape the hatch to the wing, then drill at the marks with a 1/16" drill bit. Remove the hatch and re-drill
the holes in the hatch with a 3/32" drill bit. You can toughen the wood around the holes in the hatch by applying thin
CA. Finally, mark the hatch to indicate the correct wing panel and
an arrow pointing forward to help with orientation later.
 Mark the position of the wing bolt block on the bottom of
the wing by poking a few pin holes through the bottom center
sheeting. You will need to know the block's position later when
the wing bolt plate is installed.
 Glue the root TE extensions to the wing, again using the
plans as a guide. Fill in the gap on the bottom of the wing with
scrap balsa sanded to fit. When dry, trim the inboard end flush
with W-1.
 Cut a flap from the material provided in the kit. Sand the ends square, leaving about a 1/16" gap at each end
for clearance. Inset a 1/16" plywood control horn pad into the bottom of the flap, positioned as shown on the plans.
 Cut an aileron and install its control horn pad just as you did for the flap.
 Now is a good time to drill the flaps and ailerons for their control horns. The flaps use short horns (one left-
hand, one right-hand), and the ailerons use the long horns. Position the horns carefully, mark the mounting holes,
then drill at the marks with a 3/32" drill bit. I like to use a drill press for accuracy; prop up the surface so the ply pad is
perpendicular to the drill. Harden the wood around the holes using thin CA. NOTE: The flap horns are positioned
back from the hinge point to minimize the vertical displacement of the pushrod at full flap deflection. R54
WING PANEL DETAILS, continued...
12
Wing Hatch
Balsa Doubler
Use Six #2 x 3/8”
Sheet Metal Screws to
Mount the Hatch to the Wing

Clear your bench! You need some room to maneuver when you join these big wing panels. The center
wing joint is obviously a critical part of the structure. Take your time and use plenty of epoxy.
 Cut away the slots for the dihedral braces in ribs W-1, W-2, and W-3. Make a rough cut with an X-Acto knife and
smooth up the edges of the slots with a thin sanding stick.
 Trial fit the dihedral braces in each wing panel. You will need to sand
the bottom edge of the front brace and both the top and bottom edges of the
rear brace to match the angles of the spars. You want the braces to fit
snugly, but not so tight you have to force them in. Dry assemble the wing
and make sure everything aligns as it should.
 Ah, the moment of truth!
Join the wing panels using a big batch of slow-dry epoxy. I like to use 3-hr.
epoxy, which normally gives a working time of 45 minutes or so. Coat the
edges of the braces, the spars and shear webs in the wing, and the W-1
ribs. Before the glue dries, pin the LE and TE to maintain alignment.
Stretch masking tape tightly from wheel well to wheel well to help pull the
wing panels together. Wipe away any excess epoxy with a rag soaked
with alcohol. Set the wing aside to dry thoroughly.
 Inspect the braces and your glue joints carefully. If necessary, mix up
another batch of epoxy and re-glue any dry spots or gaps.
 Trim the top center sheets for each wing panel and glue them in place
with yellow glue. I suggest doing one side at a time, using weights to hold
the panel down on your flat building board until dry.
 Inlay the 3/32" plywood wing bolt plate in the bottom of the wing.
Using the pinholes you made earlier as a guide, center the plate on the
wing bolt blocks and trim away the sheeting to fit the plywood. Score the center of the plate with a sharp knife and
crack it gently until it matches the dihedral angle, then glue it in place.
 If you haven't done so already, now is a good time to give the entire
wing a good sanding. You want to avoid sanding the sheeting as much
as possible (to avoid the "starved dog" look). However, there are areas
that will need attention like the joints between the center sheeting and
the LE and TE sheeting.
 Fiberglass tape is provided in the kit to reinforce the center wing
joint. I use a light mist of 3M 77 Spray Adhesive on the tape to hold it in
place on the wing, followed by a coating of slow-dry epoxy. The epoxy
should soak through the glass and bond with the wood. Scrape away
excess epoxy and use an alcohol-soaked rag to wipe up any messes
before the epoxy dries. R54
13
About the Dihedral Angle
For the technical-minded amongst you,
the R54 was designed with three degrees
of dihedral measured on the bottom of
the wing. The usual method of laying
one panel flat and measuring the height
of the opposite wingtip above the table is
not really necessary with this model. To
my way of thinking, the precision of the
angle is not as important as making sure
there is a gap-free center wing joint. It
would be pretty difficult to be off more
than a fraction of a degree with the two
large dihedral braces setting the angle.

The tail feathers are simple, all-sheet surfaces that build fast and easy. You can build these parts any
time during construction. They will come in handy during fuselage construction when you are routing
the pushrods, so let's get them done now and set them aside for later.
 Let's start with the vertical stabilizer (fin). I recommend yellow glue (aliphatic resin) for all of the sheet balsa tail
surfaces because it's easier to sand smooth. CA tends to leave hard ridges at the glue joints that are difficult to make
"invisible". Pin and glue the FIN-1, FIN-2, and FIN-3 parts over the plan, being careful to align the bottom edges.
 Cut the front fin post from the 5/16" x 1/2" balsa stick provided
in the kit. You can leave the top end of the stick long; it will be
trimmed later. The bottom end of the stick should match the angle
shown on the plan.
 Now add the FIN-4, FIN-5, and FIN-6 pieces, again aligning
their bottom edges. Allow to dry
 Remove the fin from the board and carefully sand the top edge
smooth and straight. Pin the fin over the drawing again and add the
FIN-7 piece. You want the front/forward end of FIN-7 to match the
plans. When dry, remove the fin from the building board and trim the rear edge of FIN-7 flush with FIN-1.
 Cut another stick for the rear fin post and glue it in place. When dry,
trim the top end flush with FIN-7. You will also need to add a tiny scrap of
balsa at the front point of FIN-6
 Sand both sides of the fin smooth. I like to attack this with an 80-grit
sanding block until the glue joints are virtually smooth followed up with
150-grit. Using this process, you may sand off up to 1/32" from the
nominal wood thickness of 5/16", which is acceptable. Round off the fin
LE, but leave the front tip squared off as shown in the photo.
 Cap both ends of the rudder with 5/16" sq. balsa. When dry, sand the caps to match the rudder contour. You will
notice that the TE thickness increases near the tip. It's okay to leave it that way, but purists (like me) will want an even
thickness along the entire TE. This is actually fairly easy to do using a few swipes of a sanding block. A carefully
drawn line, centered on the TE, will help guide your work and indicate that both sides have been sanded evenly.
NOTE: The actual thickness of the TE is not critical, but I do recommend that you leave it squared off, which is less
likely to flutter than a TE that is rounded off. The recommendation holds for all of the R54's control surfaces.
 Temporarily tape the rudder to the fin, using the plans to accurately position the bottom edge of the rudder. Sand
the top of the rudder to match the contour of the fin.
 Inlay a 1/16" ply control horn pad in the right side of the rudder using the plan as a guide. Do not install the
rudder control horn at this point - it will be installed later to align with the end of the pushrod.
Finished Vertical
Stabilizer
Add Scrap
14

 Now let's build the horizontal stabilizer (stab). Pin and glue the three STAB-3 pieces over the plan, followed by
the STAB-2 piece and the two STAB-1 pieces. Allow to dry.
 Remove the stab from the board, and trim the corners off the most forward STAB-3 to match the angle of the stab
LE. Sand the LE smooth and straight, then add the 3/8" sq. balsa leading edge sticks. Trim the sticks for a tight joint
where they meet at the front tip of the stab. Allow to dry.
 When dry, trim off the leading edge sticks at the tips and sand the outboard ends of the stab. Now you can glue
the two STAB-4 stabilizer tips in place.
 Sand the top and bottom surface of the stabilizer smooth, and round off the leading edge and tips.
 Sand the balsa elevator to an even TE thickness if you wish.
Trial fit the elevator to the stab, and sand the ends of the elevator
(if necessary) for about 1/16" clearance at each end.
 The STAB-4 tips need to be sanded to match the taper of the
elevator. Tape the elevator to the stab, keeping the ends of the tape
about an inch away from the tips. To really hold the elevator in position,
insert a straight pin at an angle through the elevator TE and into the
STAB-4 piece at each end. Now you can carve and sand the STAB-4
pieces to match the taper of the elevator.
 Once again using the plans, draw an accurate centerline on the
top surface of the stabilizer (choose the smoothest side to be the top).
Carefully cut the two holes required for the fin posts. The holes should
be centered on the centerline that you just drew, and spaced to fit the
fin that you built earlier.
 Inlay a 1/16" ply control horn pad in the bottom of the elevator. Use the plan as a guide - you will notice that the
pad is offset from the center line to better accommodate the control horn. Again, hold off on the actual installation of
the horn until later, when it can be aligned perfectly with the installed pushrod. R54
TAIL SURFACES, continued...
Insert Straight
Pin Here
Finished Horizontal
Stabilizer
15

We're making progress! It will help if you have your servos and nose wheel retract on hand for some of
these subassemblies.
 Find the coiled cable and nylon housing for the elevator and rudder
pushrods and cut them each into two pieces: 50" for the elevator and 48"
for the rudder. Lay the housings out straight somewhere out of the way,
and tape the ends so they can remain straight for a few days (or weeks).
Doing this will help relieve some of the curliness.
 Add 4-40 blind nuts (included with the BTE retract package) to the
front of F-2 for the nose wheel retract unit. The retract should be centered
left-to-right and the top flanges should be in line with the top of F-2. Make
sure the beveled bottom edge of F-2 is facing the proper direction. Lock
the blind nuts in place with CA.
 Separate the SIDE-5 pieces from
the hatch sides using a scroll saw or a
bandsaw to complete the cuts.
 Cut apart F-3/H-3 and F-4/H-4 using the plans as a guide. Use a
knife, rather than a saw, to minimize the amount of material that is cut
away. Tape the parts back together temporarily - they will be assembled
into the fuselage as a unit.
 Prepare the F-5 bulkhead by adding two F-5D doublers. Drill through
the two wing dowel holes with a 1/4" drill bit. Connect the drilled holes at
the top of F-5 to make two slots for the control cables.
 Glue the servo mount doubler to the bottom of the lite-ply servo
mount, then make a centered cutout for your elevator and rudder servos.
The overall width of the cutout should be about 2-1/4", and the distance
from the front to the rear should match your servo length plus 1/16". Add
the two balsa braces to the bottom of the mount. Position your
servos spaced apart as shown on the plans, then mark the
mounting holes, drill, and mount your servos in place using the
hardware that came with your servos. NOTE: Some turbine flyers
omit the rubber servo grommets, thinking there's little vibration and
it removes a possible source of linkage slop. I went that route with
the first R54, but now think using the grommets is still a good idea.
 With servo arms in place on the servos, glue the entire servo
mount assembly to the front of F-5. The servo arms must be
aligned vertically with the pushrod slots at the top of the bulkhead.
Remove the servos.
Align Servo Arms
With Slots
16
F-5
F-5D
(2)
F-3
H-3
F-4
H-4
F-2Align Parts
Upside Down
As Shown
SIDE-5
F-5
Cut
Here

 Cut the boat tail jig into two pieces, again using a knife. Tape the pieces back together. Eventually, the rear
piece will be glued permanently into the structure, and the front piece will be removed.
 Prepare your lite-ply receiver shelf to suit your planned radio
installation, which may differ from what is shown here. I like to put
the cup hooks in place now, because clearance inside the fuselage
can be an issue if you wait until later. The front end of the shelf is a
handy place for the receiver switch, but it's up to you.
 Glue the D-1 receiver shelf positioners to the lite-ply doublers.
CAUTION! Be sure to make a right-hand and a left-hand fuselage
doubler. It is critical to align the positioners with their bottom edges
flush with the bottom edge of the doubler.
 Do the same for the D-2 ECU shelf positioner, but be careful!
D-2 is not a rectangle. Use
the plan to mark the bottom
edge and add an arrow
pointing forward on each D-2
to aid in positioning.
 The fuselage plans are
printed in two pieces. Cut one
(or both) accurately along the
join line, then tape the two
pieces together. Use a long
straightedge to check some of the straight horizontal lines to be sure the plan sheets are aligned properly.
 Build the two 1/4" balsa fuselage sides over the plans (protected with wax paper). Start by pinning down SIDE-1.
You may see slight discrepancies with the plan, but I suggest making sure it is positioned accurately along its rear
edge and the wing saddle. Add SIDE-2 through SIDE-5,
in that order, using yellow glue or thick CA.
 Lay the fuselage side back on the plan and draw the
positions of the F-7 and F-8 bulkheads on the INSIDE of
each fuselage side. NOTE: The notches on the SIDE-1
pieces will go on the OUTSIDE surface of the fuselage.
You should now have one left-hand and one right-hand
fuselage side assembly.
R54
SIDE-1
SIDE-2 Don't worry if
it's oversize - it will be
trimmed later
SIDE-3
Watch
the Notch
D-1
D-2
FUSELAGE SUBASSEMBLIES, continued...
17
Receiver
Shelf

Now let's have some fun. The basic framework of the fuselage goes together fairly quickly. Pretty soon
you will be putting on the wing and taping on the tail and making jet noises in your workshop…
 Trial fit the lite-ply fuselage doublers to the fuselage side. It is very important that both doublers are positioned
identically on their respective sides. You won't have any problems if you pay attention to these three critical areas:
- Aft Edge must align with aft edge of SIDE-1. Again, be careful to make a right and a left side.
- Wing Saddle must align with wing saddle curve of SIDE-1. It should line up perfectly except perhaps right at the LE.
- Top Nose Edge must be spaced 3/8" from top edge of SIDE-5. There should be about a 1/8" gap at the very front.
Notice that the doubler actually extends about 1/4" above the balsa sides in the
hatch area, so you should tape the doubler in place, flip the assembly over,
and mark the "no glue" zone on the
doubler. For glue, I like to use thick
CA, but epoxy would work as well
(avoid yellow glue - it can cause
curling on big surfaces like this). To
avoid having the doubler slip around,
arrange some straight pins as shown in the photo to act as guides for the
doubler as you lay it into place.
 In the kit you will find two pieces of 1/2" balsa triangle stock with a
"nipped" edge. Apply this material to the fuselage sides with the nipped
edge resting against the doubler. You will need a long piece along the
bottom of the doubler and a short
piece along the top of the nose.
If necessary, use a razor blade to
make partial cuts in the triangle
stock to make it easier to bend.
 Apply a normal piece of triangle stock to the top of the fuselage sides.
The aft edge of the stick should end 1/4" forward of the little jog on the top edge of SIDE-4. Notice that the top of the
fuselage begins a gentle curve near the hatch cutout.
 Finally, add a piece of 1/2" triangle to the top edge of each hatch side. At the risk of becoming annoying, be sure
to make a left and a right.
 Add a 5/16" sq. balsa stick flush with the bottom edge of the
fuselage tail boom. The stick should start at the doubler and end 3"
forward of the bottom corner of SIDE-4.
 Tape the hatch sides firmly in place on the fuselage sides - do
not glue! I used blue masking tape so it would show up well in the photos.
18
3/8"
Align Here
No Glue
Zone
3" 1/4"
SIDE-4
5/16" SQ. BALSA

 Tack glue F-5 and F-6 to one of the fuselage sides, using a triangle to
make sure they are perpendicular. Now add the lite-ply fuel tank
compartment top (big rectangle) along with the opposite fuselage side.
Tack glue the parts, check the fuselage alignment over the plans, then glue
them all firmly. These parts will form a self-aligning box that is the core
section of the fuselage.
 Dry assemble F-1 through F-4 in the nose of the fuselage, using tape
at the nose to hold everything together. You can check the overall
alignment over the plans, but it's difficult. This is where a trained eyeball
will come in handy. Stand a few feet in front of the nose and look for any
hint of twists or one side bending more than the other (the banana effect).
When you are satisfied that it's straight, start spot gluing the parts with
medium CA. CAUTION! Be very careful to keep the glue away from the
joints between the hatch sides and the fuselage sides.
 Glue in the lite-ply receiver shelf and ECU shelf.
 At this point there is a lot of bending pressure that might be fighting you, particularly near the nose. Apply tape or
temporary spreader sticks as necessary to hold things in their proper
position. Trial fit the 1/4" plywood H-1 to make sure it fits, then glue it in
place on the hatch.
 Slide H-2 into position on the hatch. The final position is not critical,
you just want to slide it far enough forward that it causes the hatch sides to
bulge just a tiny bit
away from the lip of the
fuselage doubler. You
want just enough of a
gap to give the hatch a little wiggle room so it's easy to put in place
on the fuselage later on. Make sure the top edge of H-2 is even
with the top of the hatch sides and glue it in place.
 Dry assemble F-7, F-8, and the 1/4" balsa stabilizer mount on
the aft end of the fuselage, again using tape and pins as necessary
to hold things in place. The fuselage top view on the plans is very
helpful for checking alignment during this step. When satisfied that
everything is positioned properly, glue with thin or medium CA.
 Glue the 3/32" plywood turbine mount to the bottom of the tail boom.
Add the 3/16" plywood turbine mount doubler to the center of the turbine
mount on the inside of the fuselage.
 Sheet the bottom of the fuselage between F-6 and the turbine mount
with 3/32" balsa applied cross-grain.
FUSELAGE CONSTRUCTION, continued...
19
Turbine Mount
Doubler
F-8
F-7
Temporary Balsa Spacer
Receiver Shelf
H-2
H-3
H-1