Stevens Aero Model SHAFT25e User manual

© 2007 Stevens AeroModel. Page 1 of 35
SHAFT25e
Instruction Manual - Version 1.01
Span 52 in. / Length 45 in. / Area 600 Sq. In. / Weight 32-40 oz.

© 2007 Stevens AeroModel. Page 2 of 35
***Cautions***
1. Power system.
Overpowering this model with a heavier / more powerful system is not recommended.
Stevens AeroModel recommends a power system no greater than 600W, a maximum
pitch speed of 50 mph, and a maximum all up weight (AUW) of 40 oz.
Outrunner motors like the Hacker A30 transmit a great deal of stress to the motor
mount. DO NOT run your motor up until you have verified that your blade is accurately
balanced and in perfect track. Finally, disable your ESC’s prop braking function.
2. Throttle management.
Similar to full-scale and giant scale models this high performance model requires
careful throttle management. When tracking through a down-line it is mandatory to
govern the use of throttle, slowing the models descent, to avoid over stressing the
airframe.
3. Flying off grass.
The model has been designed to fly from a smooth dirt or paved surface. If you must
fly from a turf field run a large diameter narrow wheel and remove wheel pants (if
equipped).
WARRANTY
Stevens AeroModel guarantees this kit to be free from defects in both material and workmanship
at the date of purchase. This warranty does not cover any component parts damaged by use or
modification. In no case shall Stevens AeroModel’s liability exceed the original cost of the
purchased kit. Stevens AeroModel reserves the right to change or modify this warranty without
notice.
In that Stevens AeroModel has no control over the final assembly or material used for final
assembly, no liability shall be assumed nor accepted for any damage resulting from the use by
the user of the final user-assembled product. By the act of using the user–assembled product,
the user accepts all resulting liability.
If the buyer is not prepared to accept the liability associated with the use of this product, the buyer
is advised to return this kit immediately in new and unused condition to the place of purchase.

© 2007 Stevens AeroModel. Page 3 of 35
REQUIRED TO COMPLETE KIT:
Kit Contents:
Computer drawn Plan Set
Illustrated Instruction Manual
Laser Cut Parts Inventory (on next page)
2 - .045” x 24” length music wire
2 - .045” x 12” length music wire
1 - 1/16” x 12” length music wire
2 - .09” OD x 18” length push-rod housing
2 - 1/4” square x 24” length balsa leading edge
1 - Pre formed wire landing gear (1/8” diameter music wire)
Hardware Bag
•2 – Pkg. DuBro RC Razor Control Horns [4] (DUB936)
•1 – Pkg. DuBro RC Micro II EZ-Link [4] (DUB920/27805)
•2 – Pkg. DuBro RC Micro E/Z Connector [4] (DUB845)
•1 – Pair 3.0” Foam Wheel [2]
•2 – 1/8” Wheel Retention Star Washers
•6 – 4-40 Blind Nut
•2 – 4-40 x 1/2” Bolt
•4 – 4-40 x 3/8” Bolt
•1 – Package Gum Rubber Bands #33 [10]
•2 – 3/16” Neo. Magnet
•1 – 1/4” Dia. x 4-3/4” Length Hardwood Dowel
•2 – 3/16” x 4-3/4” Length Hardwood Dowel
•1 – Laser Cut Basswood Elevator Joiner
Recommended Finishing Items:
1. 2 Rolls of AeroFILM Lite (Solarfilm Solite, or Nelson Lite Film may be substituted).
Suggested Electronics:
1. 4 - Micro Servos (Hitec HS-81) (Requires 2 Additional HS-65 Servos for Flaps Option)
2. 1 - 6” Y-Servo Extension
3. 2 - 6” Servo Extension
4. 1 - Receiver 4-6 Ch.
Power System:
1. Hacker A30-16M Direct Drive or VSport 350 (VS301316)
2. 11x5.5 – 11x7 APC-E Propeller
3. 11.1v 2200mAh LiPo (Rated for 20C discharge).
4. Castle Creations Thunderbird 36 or Phoenix 35 ESC
Items You May Need:
1. Thin CA (super glue)
2. Medium CA (super glue)
3. Razor Blade(s)
4. Fine Grit Sand Paper and Sanding Block
5. Clear Tape
6. Balsa Wood Filler

© 2007 Stevens AeroModel. Page 9 of 35
Tail Feathers
General Construction Notes: This kit features our proprietary Trus-Loc™ system as such typical “stick” type construction
has been replaced by precisely cut “stick” components that are keyed to fit in only one direction. The “knuckles” of the
truss are identified with an alpha-numeric use this to match adjoining truss components “A” to “A” and “B” to “B” etc. If a
part does not fit properly chances are very good that you have the wrong part or the part is in backwards. Under no
circumstances should you need to fill significant gaps or re shape the parts.
1. All of the parts to create the tail feathers are located on the 3/16” balsa sheets “SHAFT-17/21 and 18/21”. This
kit is a bit special as we have included an alternate set of Horizontal Stabilizer and Elevator (for those who
prefer the “squared off” look of the stick plane – thus you’ll find an extra sheet 17/21 in this kit distribution)
Remove parts from the sheet with a sharp #11 hobby blade. Assemble the parts on top of your plan sheet
using the drawings on the sheet to reference part location and orientation. Frame up all tail feather components
as illustrated below.
2. Join the elevator halves. Locate the provided 3/16” basswood laser cut elevator joiner, and prepare to bond the
two elevator halves together. Tip: Lightly sand the bass wood elevator joiner and elevator halves just enough to
remove the laser burn mark where these two components will be bonded (do not significantly alter the shape of
the parts)– this produces a stronger bond for this high stress area. Use a straight edge to align elevator halves
with bass wood joiner and bond with a high quality medium weight CA glue (Mercury 100XF works brilliantly
here).

© 2007 Stevens AeroModel. Page 10 of 35
Fuselage
General Construction Notes: This fuselage utilizes an improved tab and notch construction method pioneered by Stevens
AeroModel. Each component precisely interlocks using unique tab and notch sizes to allow the parts to only fit in one
direction. Where parts orientation can be reversed or inverted parts are scribed with a reference such as “top” or “front”
for proper orientation. Throughout construction we suggest dry-fitting all components, and using minimal amounts of glue
at tab and notch locations only to hold parts together. By dry fitting the fuselage, each successive component will assist
with pulling the assembly square and straight.
1. Begin construction by finding the 1/8” balsa sheets “SHAFT-04/21, 15/21, and 16/21.” Locate and assemble the
parts labeled FSa and FSb along with the corresponding interlocking truss parts to create two fuselage sides.
Tip: us a straight edge to align the fuselage sides prior to bonding with thin CA glue. Assemble F11a and F11b
to create one F11 former. Assemble F7a, F7b, and F7c to create one F7 former. Assemble H2a, H2b, and H2c
to create one H2 battery hatch component (make certain scribe lines running lengthwise along H2 components
are on the same side). See illustration below and plan set for further reference.
2. Assembly of the fuselage crutch begins. USE NO GLUE TO BOND THE PARTS UNTIL INSTRUCTED.
Locate the 1/8” lite plywood former part F0 and 1/16” plywood former part F2. Note: Both F0 and F2 are scribed
“TOP” to indicate proper top-side orientation. Ensure “TOP” faces up AND forward (towards motor). Place F2
through the large lightening hole in F0. Align the notches in F2 with the inside rails of F0, then rotate F2 into the
receiving notches of F0. Hint: This fit is snug so gently coax the part into position working one side, then the
other… be mindful of how much force you use so that you do not break the part. See illustrations below.
3. Locate the 1/8” lite plywood former F1 – place on your work table with the scribed part number facing down.
Install four 4-40 blind nuts and retain with medium CA glue (careful here – you do not want glue within the
threaded portion of the blind nut).

© 2007 Stevens AeroModel. Page 11 of 35
4. Now install the former F1 to the fuselage crutch F0 observing proper forward and top-side orientation. Finally,
locate the 1/16” plywood former F3 and key to the fuselage crutch assembly as illustrated below. Again, this
formers installation direction has been identified with the scribing of “TOP” on the part to signal the top and
forward orientation of the component.
5. Next, key the 1/16” plywood G1 landing gear supports to both sides of the fuselage crutch, as illustrated in the
photo below.
6. Test fit the completed fuselage crutch to one of the 1/8” balsa FS fuselage sides. Any failure to follow the
proper top-side part orientation will be revealed here. If the tabs in your fuselage crutch do not align with the
notches in the fuselage side you will need to re-visit the crutch assembly and pay careful attention to the top-
side part orientation (as instructed, you haven’t glued the crutch right?). With the test fit successful, tack glue
each of the crutch parts together. Finally, tack glue both 1/8” balsa fuselage sides to the crutch at tab and notch
locations as illustrated below.

© 2007 Stevens AeroModel. Page 12 of 35
7. Locate the 1/8” lite plywood part F00 and lightly sand a chamfer to the edges of the two long legs allowing F00
to readily slide within the keyed pockets of the central crutch F0. Install F00 as illustrated in the photo series
below, square to fuselage, and retain with thin CA glue.
8. DO NOT OVERLOOK THIS STEP! F1 will bear a considerable load from in-flight stresses from the motor and
propeller. With the fuselage sides joined to the crutch, and access to the F1 firewall still un-restricted, now is
the time to thoroughly bond former F1 to the forward portion of the crutch and the fuselage sides. Wick liberal
amounts of thin CA glue along the joints where F1 touches the fuselage assembly. Once the thin CA glue has
cured, build up a small fillet of medium CA glue along the same joints.
9. Before the front of the fuselage is sealed up we need to install the balsa cross grain doublers for the forward
wing dowel mounts. Locate the 3/32” balsa parts marked F10a and install these within both sides of the
fuselage assembly just forward of former F2. See the plan set and photos below for further guidance.
10. Assemble former F8 from a laminate of 3/32” balsa and 1/32” plywood. Locate the 3/32” balsa part F8a and the
1/32” ply part F8b and, while carefully matching sides glue together to create a very strong F8 former!

© 2007 Stevens AeroModel. Page 13 of 35
11. Key 1/8” balsa former F7 (assembled in step 1) to proper location on top-side of fuselage assembly. Square
fuselage and parts to your flat work surface and proceed to glue former F7 in place with thin CA glue. See first
illustration below. Next, invert fuselage and key former assembly F8 (from previous step 10) to proper location
on underside of fuselage assembly WITH THE BALSA HALF FACING OUTSIDE. Square fuselage and parts
to your flat work surface and proceed to glue former F8 in place. See second illustration below.
12. Locate the 1/16” ply part G2a and 1/32” ply part G2b. Glue these on top of each other carefully matching the
outer edges to create part G2. Next, key the assembled part G2 landing gear re-enforcement strap to the
notches provided in the underside of the fuselage as illustrated below. Retain with thin CA glue followed by and
application of medium CA glue along the inside joints.
13. Locate previously assembled 1/8” balsa former F11 (assembled in step 1) and install two (2) 4-40 blind nuts as
illustrated below. Retain blind nuts with medium CA glue. Do not allow glue contact with the threaded portion
of the blind nut.

© 2007 Stevens AeroModel. Page 14 of 35
14. Before applying glue locate the 1/16” plywood former F6, and key it to 1/8” balsa former F11, and fuselage
sides, as illustrated below. Square fuselage to building board and tack glue parts into position at tab and notch
locations. VERY IMPORTANT: The “rim and spike” portion of the blind nut should be located within the
fuselage body (on the same side as the large lightening hole in former F6) so that the threaded portion
of the blind nut is exposed to the underside of the fuselage. Pay close attention to the illustrations
above and below so that you don’t inadvertently install part F11 upside down.
15. Bond 3/32” balsa former F12 to fuselage as illustrated in the first photo below. Next, key 3/32” balsa part F13 to
underside of fuselage atop F12, and spanning fuselage sides, and former F3. Make certain that F13 fits flush
with fuselage sides and is properly seated at all tab and notch locations. Now, square your fuselage assembly
to your flat work surface and tack glue part F13 into position at all tab and notch locations.
16. Before we seal up the aft portion of the fuselage, we have some important business to attend to. First, install
the 3/32” balsa cross-grain doublers F10b within the fuselage assembly, flush with former F3 and F14, as
illustrated in the first photo. *** OPTIONAL AS THE DEFAULT SERVO ARRANGEMENT IS TO USE
PUSHRODS DESCRIBED IN STEPS 23 and 24 Now move aft within the fuselage, and install 1/32” plywood
servo pocket supports SR3 to each side of the assembly (within the fuselage), as illustrated in the second photo
below. ***

© 2007 Stevens AeroModel. Page 15 of 35
Now is a good time to verify that the push-rod housing will easily fit within the laser cut holes of formers F3, F4,
and F5. Locate the 18” length of plastic .090” diameter pushrod housing and test fit to holes provided in these
formers. Adjust the hole size using a rat-tailed file if necessary.
17. Complete the mid section of the aft fuselage assembly by first installing the 1/16” plywood formers F4 and F5 as
illustrated below. Next, key the 3/32” balsa former F9 to the top of the fuselage assembly spanning formers F3,
F4, F5, F6 and fuselage sides, as illustrated below.
Here’s a neat assembly trick. Use a scrap piece of the 3/16” balsa stock from which your tail surfaces were cut.
Slip this scrap in the slot at the aft end of the fuselage to assist in properly seating the parts at the tail section.
Carefully tack glue the tail section, remove the scrap, then complete the tail with a good application of thin CA
along the inside surfaces. JUST BE CAREFUL NOT TO GLUE THE SCRAP WITHIN THE TAIL SECTION
SLOT!
18. Final glue all fuselage parts. For the most part we have been utilizing thin CA glue to hold parts in position
while we complete the fuselage assembly. At this point it’s time to finalize the fuselage by re-visiting every
surface to surface joint with thin CA glue making certain that all parts are securely bonded. Hold you fuselage
flat against your building surface while bonding to ensure that it remains straight.

© 2007 Stevens AeroModel. Page 16 of 35
19. Battery hatch assembly: Locate the 3/32” balsa parts H1 and H2 (H2 assembled in step 1). Align H1 atop H2
using the scribe marks on H2 and vent hole in parts to assist with proper centering of H1. While holding the
hatch assembly flat on your work surface proceed to wick liberal amounts of thin CA between parts. Finally,
glue one of the 3/16” diameter neo. magnets into the 3/16” diameter hole, as illustrated in the second photo.
20. Install battery hatch catch within fuselage assembly. Locate the 1/16” plywood parts H3 and H4 and install
these to the fuselage using the plan sheet and illustrations below to guide your work.
21. Complete assembly by installing the second neo. magnet within the assembled catch. VERY IMPORTANT:
Magnets are polarized. They will attract with great force and will likewise repel each other with great
force if one of the poles is reversed. Check to see that magnets stick to each other. Tip: Mark
contacting faces with permanent marker. Install the second magnet with the marked side facing out.
Double check that when the hatch is installed to the fuselage it will be attracted to the catch. Glue the
magnet to the catch assembly by wicking thin ca glue around the magnet. Once the glue has dried you can pop
the battery hatch on to the fuselage assembly in preparation for final sanding.

© 2007 Stevens AeroModel. Page 17 of 35
22. *** OPTIONAL STEP APPLIES TO SQUARE TAIL SURFACE ONLY DO NOT COMPLETE THIS STEP IF YOU
PLAN TO RUN THE ORIGINAL ROUNDED/SWEPT HORIZONTAL STABILIZER. If you’ve decided to run the
square Horizontal Stabilizer and Elevator assembly you’ll need to install a the 3/16” balsa part marked “PLUG”
located on the same sheet you constructed this tail group from. The “PLUG” installs as illustrated below – CA it
in to complete the finished look of your fuselage when running the alternate set of flying surfaces. ***
23. Prior to installing the two 18” lengths of plastic push-rod housing you’ll need to remove the push-rod exit “knock-
outs” which are partially cut and located on either side of the fuselage tail section. Use a sharp razor to remove
the retention tabs and knock the plugs out.
24. Prior to final sanding the model you’ll want to Install the two 18” lengths of .090” diameter pushrod tubing. First,
slip the tubing through the aft end of the fuselage through the openings left from removing the plugs in the prior
step. Left and Right tubing passes through the lightening hole in former F6, cross the tubes, then pass through
provided locating holes in former F5, F4, and F3. Tubing should extend 1/8” forward of F3 with excess length
left at aft end of fuselage. Glue the push rod tubes in position using medium CA glue (do not allow glue to get
within the tubing).

© 2007 Stevens AeroModel. Page 18 of 35
Now using a very sharp knife, cut then sand the tubing flush with the fuselage sides where they exit at the aft
end of the fuselage assembly.
25. Final sand your fuselage using a sanding block and 400 grit paper. Slightly radius the edges of the fuselage
and remove any exposed laser burn marks. DO NOT sand/modify the shape of the wing saddle.

© 2007 Stevens AeroModel. Page 19 of 35
Wing
General Construction Notes: This wing is of typical I-Beam construction with additional torsional strength derived from the
trussed sub ribs. Each component precisely interlocks using the interlocking I-beam construction method developed by
Stevens AeroModel. Throughout construction, we suggest dry-fitting all components, and using minimal amounts of glue
at tab and notch locations only to hold parts together. By dry fitting the wing, each successive component will assist with
pulling the wing square and straight. It is not required to pin the wing to your building surface. In-fact, most of your
building will be done above the board. You will, however, require a flat surface to set the wing on top of for final gluing of
the assembly.
One interesting feature of the SHAFT 25e kit is our incorporation of provisions for quad / split aileron / flaps. In this case
the ailerons are split into two units. This is a popular setup with pilots of “stick” type planes. Just so there is no confusion
we have built in provisions to assist the builder with mounting and rigging this setup beyond showing you where the parts
assemble the builder is on their own with implementing the quad / split aileron / system at the time of publication Stevens
AeroModel does not offer technical assistance for implementing this setup.
1. Begin construction by assembling major parts from sub assemblies: W1a and W1b to create W1 turbulator with
jig. W2a and W2b to create two (2) W2 turbulators. S1a and two (2) each S1b to create S1 spar webbing, S2a
and S2b to create two (2) spar web caps. T1a, T1b, and T1c to create T1 trailing edge. Assemblies are joined
along the pre-cut scarf and finger joints. Reference parts along a straight edge and bond at the scarf joints
using medium CA glue. See illustration below for parts reference.
2. Complete the S1 spar web assembly. Locate the previously assembled 3/32” balsa S1 spar web and the 1/16”
plywood S1c spar web doubler. Align S1c on top of the S1 assembly, centering S1c on top of S1 at the wing
center section. Apply liberal amounts of medium CA glue between the parts to laminate the ply spar web
doubler to the spar web assembly. Note: S1c should not cover any of the rib (and sub-rib) notches in S1 and
should end right at the inside edge of the notches for sub rib R2a. See illustrations below.

© 2007 Stevens AeroModel. Page 20 of 35
3. Key the complete re-enforced S1 assembly atop one of the S2 spar cap strips. Tack glue these parts together
at the tab and notch locations. Now locate the two (2) 3/16” balsa R1 ribs and key these to the slots in S1 on
either side of the center section of the S1 assembly. VERY IMPORTANT: The plywood doubler laminated
previously to S1 must face forward toward the wing leading edge. Set the second S2 spar cap aside as
this will not be joined to the assembly until much later. See illustration below.
4. *** OPTIONAL STEP If you plan on running the split aileron setup now or in the future you’ll want to remove the
circular knock-outs in ribs R2 and R3 to allow the outboard aileron servo wires to pass through. ***
5. Fill out the remainder of the wing by installing 3/32” balsa wing ribs R2, R3, R4, and 1/8” balsa rib R5 to the S1
spar web. Use the plan sheet as a guide for rib location. While not required, you may tack glue the wing ribs to
S1 at as long as you do so only where the rib meets the notches in the lower spar cap.

© 2007 Stevens AeroModel. Page 21 of 35
6. Servo pocket selection. The SHAFT 25e ships with provisions for several aileron servo setups. The
recommended setup is to run two (2) HS-81 servos one (1) each per side. For this default setup you’ll need to
locate and install the following parts 1/32” ply SR81a and 1/8” balsa SR81b servo pockets spanning the S1 spar
web and rib R2.
*** OPTIONAL SETUP 1 - If you choose to run the optional split aileron setup you have some choices to make
regarding servo pocket sizes. Option 1 run two (2) each HS-81’s inboard for the inboard aileron/flap surface
and two (2) each HS-65’s for the outboard aileron/flap surface. This is a good option if you wish to build the
SHAFT 25e with a single movable aileron surface then later upgrade/experiment with the quad aileron/flap
setup. For this setup you’ll need to locate and install the following parts 1/32” ply SR81a and 1/8” balsa SR81b
servo pockets spanning the S1 spar web and rib R2 and parts 1/32” ply SR65a and 1/8” balsa SR65b servo
pockets spanning the S1 spar web and rib R4. ***
*** OPTIONAL SETUP 2 – Option 2 is the best option for running the quad/flap/aileron system as it utilizes four
of the same type servo so you can be assured that the split ailerons will move in unison when functioning as
ailerons. For this option you’ll run four (4) each HS-65’s inboard and outboard for the aileron/flap surfaces.
This is a good option if you intend to set up the SHAFT 25e with the quad aileron/flap setup from the get go.
For this setup you’ll need to locate and install the following parts 1/32” ply SR65a and 1/8” balsa SR65b servo
pockets spanning the S1 spar web and rib R2 and spanning the S1 spar web and rib R4. ***

© 2007 Stevens AeroModel. Page 22 of 35
Select your aileron setup and corresponding servo pocket parts per the guidance on the previous page. Now,
go ahead and bond the 1/16” ply servo pocket in place making certain it is firmly seated against spar web, spar
cap strip and rib. Bond the 1/8” balsa part on top of the plywood servo pocket and flush with the edge of the
spar cap and rib. The photo series below shows the installation of the Option 1 servo selection from previous
page. If building the default two aileron servo wing only the first three photos will apply. If building the Option 2
setup you’ll use the SR65a and SR65b parts contrary to what is illustrated in the first three photos. Clear as
mud? Dry fit the components then double check your work against the servos you’ve chosen once satisfied
complete the assembly with glue.
7. Locate the 1/8” balsa part W6 and bond to the wing center section using the notches in ribs R1 to align with the
tabs in the W6 part.
8. Key the 3/16” balsa T1 trailing edge to wing assembly (previously assembled in step 1). The notched trailing
edge should seat flush with the bottom and trailing edge of the wing assembly ribs. With the trailing edge
properly fit, tack glue the part to the assembly where it interlocks with each rib.

© 2007 Stevens AeroModel. Page 23 of 35
9. Install the 3/32” balsa W3 wing truss components. The trailing edge of W3 should be completely received
within the notches at the wing trailing edge, and fit with full contact against the spar and wing ribs at the leading
edge of W3. Dry fit all W3 parts to pull the wing assembly square. Next, key the 3/16” balsa wing tips W5 to
the assembly and tack into position with a drop of CA glue where it meets the outer wing rib and trailing edge.
Lay the wing flat on top of your building board. Then proceed to tack glue the W3 truss parts at the trailing edge
and where they contact the S1 spar and S2 spar cap.
10. Locate the 3/32” balsa sub ribs R1a, R2a, R3a, and R4a and key these to the S1 spar web as illustrated below.
Inspect the fit to make certain that the sub ribs seat flush with the web, then tack glue the sub ribs from the back
side of the web at the tab and notch joint.
11. Install 3/16” balsa LE rib doublers marked “LE2” to the left and right inside surface of ribs R1. See photos
below.

© 2007 Stevens AeroModel. Page 24 of 35
12. Locate the 1/8” balsa W1 turbulator (W2 is smaller than W1 and lacks notches). W1 is notched on one side and
should be installed to the forward most turbulator notch spanning all ribs. Next install two (2) W2 turbulators in
remaining slots atop wing ribs. See illustrations below. VERY IMPORTANT: The top surface of turbulators
W1 and W2 will fit flush with the top surface of ribs R1 and R5. Along all mid-span ribs R2 through R4
turbulators W1 and W2 will seat “proud” of the top rib surface by 3/32”. Locate a scrap piece of 3/32”
balsa and use it to reference the proper installation height of W1 and W2.
13. Install the leading edge center section 3/16” balsa parts marked “LE1”. Both of these parts can be found in the
center of the 3/16” balsa aileron parts sheet SHAFT25E 07/21 and are glued one on top of the other at the wing
center section as illustrated below.

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14. Install the 1/4” square leading edge stock. Cut the two (2) provided 24” lengths of 1/4” square balsa stock to a
length of 21-13/16”. Sand / adjust length of stock so that it easily seats in full contact within the leading edge of
the wing spanning ribs R1 through R5, bond with thin CA glue.
15. Locate the second 1/8” balsa S2 spar cap strip and install to top side of spar web as illustrated below.
16. Bond the 1/8” balsa W7 leading edge re-enforcements to the notches in rib R1. W7 should make full contact
and be centered to the 1/4” balsa wing leading edge stock as illustrated below.