Stevens Aero Model SHAFT S400 User manual

© 2007 Stevens AeroModel. Page 1 of 33
SHAFT
S400
Instruction Manual - Version 1.03 - Revised 03.28.2013
Span 39 in. / Length 35 in. / Area 340 Sq. In. / Weight 14-18 oz.
Made in the USA!
Of U.S. and Imported Parts

© 2007 Stevens AeroModel. Page 2 of 33
***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 200W, a maximum
pitch speed of 45 mph, and a maximum all up weight (AUW) of 20 oz.
Outrunner motors like the Hacker A20 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.
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. Further, Stevens AeroModel reserves the right to change or modify this warranty
without notice.
LIABILITY RELEASE
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.
THIS PRODUCT IS NOT INTENDED FOR CHILDREN 12 YEARS OF AGE OR YOUNGER
WARNING: This product may contain chemicals known to the State of California to cause cancer
and or birth defects or other reproductive harm.

© 2007 Stevens AeroModel. Page 3 of 33
REQUIRED TO COMPLETE KIT:
Kit Contents:
Rolled computer drawn Plan Sheets
Illustrated Instruction Manual
Laser Cut Parts Inventory (on next page)
2 - 24” length carbon fiber bar stock
2 - .045” x 18” length music wire
1 - 1/32” x 11.5” length music wire
2 - 3/16” square x 24” length balsa leading edge
1 - Pre formed wire landing gear (3/32” diameter wire)
Large Hardware Bag
•6 – Gum Rubber Bands #16
•4 – DuBro RC Micro II Control Horns (DUB919)
•4 – DuBro RC Micro II EZ-Link (DUB920)
•4 – DuBro RC Micro E/Z Connector (DUB845)
•2 – Rubber Wheel Retainers
•2 – 4-40 Blind Nut
•2 – 4-40 x 3/8” Nylon Bolt
•2 – 3/16” Neo. Magnet
•2 – 1/8” x 3-1/2” Hardwood Dowel
•1 – Pair Du-Bro RC 1-3/4 in. Super Lite Wheels [DUB175SL]
•1 – 3/16” x 3-1/2” Hardwood Dowel
•1 – Laser Cut Basswood Elevator Joiner
Recommended Finishing Items:
1. 1 Roll of AeroFILM Lite (Solarfilm Solite, or Nelson Lite Film may be substituted).
Suggested Electronics:
1. 4 - Sub Micro Servos (Hitec HS-55)
2. 1 - 6” Y-Servo Extension
3. 2 - 6” Servo Extension
4. 1 - Micro Receiver (10-12g)
Power System:
1. Hacker A20-20L Direct Drive
2. 9x4.7 - 10x4.7 APC SF
3. 11.1v 910-1350mAh LiPo (Rated for at least 17A Continuous).
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 4 of 33
Laser Cut Parts Inventory

© 2007 Stevens AeroModel. Page 5 of 33
Laser Cut Parts Inventory

© 2007 Stevens AeroModel. Page 6 of 33
General Assembly Instructions
Thank you, for purchasing this Stevens Aeromodel SHAFT – “Super Hi-Performance Aerobatic Flight Trainer”. This kit
provides the builder and pilot a refreshing change of pace from heavy “ARF” style plywood box airframe construction, and
blends stick and tissue design methods of the past with state of the art CAD technology and precision interlocking laser
cut parts. The result is something you will find truly exceptional to build and fly. Please keep in mind that this kit is
intended for a novice-intermediate builder and novice-intermediate pilot as a second aileron plane. If you do not meet
these criteria it is recommended to seek help from a more experienced builder / pilot.
Best Regards,
Bill Stevens
[email protected]
Stevens AeroModel “Built to Fly”
P.O. Box 15347
Colorado Springs, CO 80935
Assembly Tips
READ THE INSTRUCTIONS and the plan sheet prior to starting any work!
Tape plans to work table. Protect plans from glue spills using the poly tubing your kit was bagged in.
Join all parts with Thin CA unless otherwise specified.
DO NOT REMOVE THE PARTS FROM THE BALSA SHEETS UNTIL REQUIRED!
DO NOT FORCE THE FIT. When in doubt, double check your parts. Removal of material should not be
required. If you feel that you have a poor connection, check first to see that the part is not upside down.
Reference each piece against the plan sheet.
Making solid glue joints: Hold parts together on top of plan sheet using moderate pressure to fit parts. Wick
Thin CA into joint. There is no need to pin parts to work table as all pieces interlock and self - jig.

© 2007 Stevens AeroModel. Page 7 of 33
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 1/8” balsa sheet “SHAFT-11/12”. Parts are grouped
on the sheet by the assembly to which they belong using a simple scribe line that surrounds the parts group.
Work only with one group of parts at a time and remove these 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 orientation. Frame
up all tail feather components as illustrated below.
2. With the tail feathers assembled as above, it is time to install the carbon fiber trailing edge re-enforcement.
Locate the carbon fiber bar stock and use the plan sheet as a reference to cut the stock to length. Heavy duty
scissors or a fine razor saw will make short work of cutting through the carbon stock. VERY IMPORTANT: To
avoid running short of flat bar stock, cut both aileron trailing edge re-enforcements NOW. Cut one from
each of the two pieces of carbon stock provided. Reference the plan sheet to measure the length. Tip:
Lightly remove the laser-burn from the bond area on the balsa part using no less than 400 grit sand paper and a
small sanding block (this is the only time during construction that we recommend removing the laser burn from
a part). We suggest using a high performance medium CA glue to bond the carbon fiber bar stock trailing edge
re-enforcement to the balsa and have found the Mercury 100XF to be superior for this application. In a pinch,
any medium weight CA glue will be adequate. Bond the carbon stock flush with the trailing edge of the Elevator
and Rudder assemblies pictured left and right below.
3. Join the elevator halves. Locate the provided 1/8” basswood laser cut elevator joiner, and prepare to bond the
two elevator halves together. Assemble the parts on top of your plan sheet using the drawings on the sheet to
reference orientation.

© 2007 Stevens AeroModel. Page 8 of 33
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 balsa sheets “SHAFT-08/12, 09/12, and 10/12.” Locate and assemble the parts
labeled FSa and FSb to create two fuselage sides. Assemble F7a and F7b to create one F7 former. Assemble
H2a and H2b to create H2 battery hatch. Note: make certain scribe lines running lengthwise along H2
components are on the same side. See illustration below.
2. Assembly of the fuselage crutch begins. USE NO GLUE TO BOND THE PARTS UNTIL INSTRUCTED.
Locate the plywood former parts F0 and F2. Note: Both F0 and F2 are scribed “TOP” to indicate proper
orientation. Ensure “TOP” faces up or 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 illustration below.
3. Locate the 1/16” plywood formers F1 and F3 and key these to the fuselage crutch assembly as illustrated
below. Again, these formers have been identified with the scribing of “TOP” on each part to signal the top and
forward orientation of the component.

© 2007 Stevens AeroModel. Page 9 of 33
4. Verify that upon completion of step 3, your assembled fuselage crutch looks identical to the first photo below.
Next, key the 1/16” plywood G1 landing gear supports to both sides of the fuselage crutch, as illustrated in the
second photo below.
5. Test fit the completed fuselage crutch to one of the 3/32” 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 3/32” balsa fuselage sides to the crutch at tab and
notch locations as illustrated below.
6. 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 fillet of medium
CA glue along the same joints.
7. Key 3/32” balsa former F7 (assembled in step 1) to top-side of fuselage assembly. Invert fuselage and key
former F8 to underside of fuselage assembly. Square fuselage and parts to your flat work surface and proceed
to glue formers F7 and F8 in place. See illustration below.

© 2007 Stevens AeroModel. Page 10 of 33
8. Key the 1/16” plywood G2 landing gear re-enforcement strap to the notches provided in the underside of the
fuselage, and glue.
9. Locate 1/8” balsa former F11 and install two (2) 4-40 blind nuts as illustrated below. Retain blind nuts with a
drop of thin CA glue. Do not allow glue contact with the threaded portion of the blind nut.
10. Before applying glue, locate the 1/16” plywood former F6, and key it to 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.
Note: Photo shows the fuselage upside down.

© 2007 Stevens AeroModel. Page 11 of 33
11. Bond 1/16” balsa former F12 to fuselage as illustrated. Next, key 1/16” 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
then tack glue former into position at all tab and notch locations.
12. Before we seal up the aft portion of the fuselage, we have some important business to attend to. First, install
the 1/32” balsa cross-grain doublers F10 within the fuselage assembly, flush with former F3 and F14, as
illustrated in the first photo. Now move aft within the fuselage, and install 1/16” plywood former SR3 to each
side of the assembly (within the fuselage), as illustrated in the second photo below.
13. 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 1/16” balsa former F9 to the top of the fuselage assembly spanning formers F3,
F4, F5, F6 and fuselage sides, as illustrated below.
14. 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 12 of 33
15. Battery hatch assembly: Locate the 1/16” balsa parts H1 and 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 third photo.
16. 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.

© 2007 Stevens AeroModel. Page 13 of 33
17. 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.
18. 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 14 of 33
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.
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 S1b to create S1 spar webbing, S2a and S2b to
create two (2) spar web caps. T1a and T1b to create trailing edge. Assemblies are joined along the pre-cut
scarf 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 1/32”
plywood S1c spar web doubler. Align S1c on top of the S1 assembly, centering S1c and S1 at the scarf joint.
Wick liberal amounts of thin 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. See illustration below.
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) 1/8” balsa R1 ribs and key these to the slots in S1 on
either side of the scarf joint for 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.

© 2007 Stevens AeroModel. Page 15 of 33
4. Fill out the remainder of the wing by installing 1/16” 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.
5. Install the 1/32” plywood SR1 servo pocket to assembly by aligning tabs of SR1 to notches in rib R2 and S1
spar web. Go ahead and bond SR1 in place making certain it is firmly seated against spar web, spar cap strip
and rib. Invert your wing assembly and bond the 1/16” balsa part SR2 on top of the plywood SR1 servo pocket
and flush with the edge of the S2 spar cap and rib R2.
6. Locate the 3/32” 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.

© 2007 Stevens AeroModel. Page 16 of 33
7. Key the 1/8” balsa T1 trailing edge to wing assembly. 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.
8. Install the 1/16” 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 1/8” 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.
9. Locate the 1/16” 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.

© 2007 Stevens AeroModel. Page 17 of 33
10. Locate the 3/32” 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 1/16”. Locate a scrap
piece of 1/16” balsa and use it to reference the proper installation height of W1 and W2.
11. Install the leading edge stock. First join the two (2) 24” lengths of the provided 3/16” square balsa stock
together using the scarf joint diagram on the plan sheet. To create the scarf joint: Overlap the two lengths of
stock by approximately 2”. Using a sharp razor blade or razor saw make a shallow cut of about 15 degrees
through both lengths of stock. Discard the scrap pieces and bond the long lengths along the angled cut you just
made. Center the scarf joint on the wing center section and cut the excess where it overhangs the ends of the
wing at rib R5. Seat the leading edge stock so that it fits with full contact within the leading edge of the wing
ribs and bond with thin CA glue.

© 2007 Stevens AeroModel. Page 18 of 33
12. Locate the second 3/32” balsa S2 spar cap strip and install to top side of spar web as illustrated below.
13. Bond the 3/32” balsa W7 leading edge re-enforcements to the notches in rib R1. W7 should make full contact
and be centered to the 3/16” balsa wing leading edge stock as illustrated below.
14. Install the 1/32” plywood W4 trailing edge re-enforcement within the notch at the wing trailing edge center
section.
15. Final glue all wing assembly parts. For the most part we have been utilizing thin CA glue to hold parts in
position while we complete the wing assembly. At this point it’s time to finalize the wing assembly by re-visiting
every surface to surface joint with thin CA glue making certain that all parts are securely bonded. Hold you
wing flat against your building surface while bonding to ensure that it remains straight.

© 2007 Stevens AeroModel. Page 19 of 33
16. Shape the leading edge. Grab your 400 grit sanding block and razor plane. Proceed to rough the leading
edge of the wing round using your razor plane then follow up with a few swipes of 400 grit paper on your
sanding block. Test fit the wing to fuselage often through this process. Just as the turbulators along mid-span
ribs sit proud by 1/16” so should your wing leading edge. That is to say, your wing leading edge should be
sanded flush with the profile of only ribs R1 and R5, and remain proud of the mid-span ribs by 1/16” (see step
10 and use scrap 1/16” balsa as a guide).
A razor plane makes short work of shaping components such as wing leading and trailing edges (we suggest
the Master Airscrew MAS4100 razor plane). If you do not have the luxury of a $7 razor plane for this project a
long sanding block or bar loaded with more aggressive grit paper (120-200) will suffice.
17. Run your sanding block across all exterior wing surfaces to remove the laser burn in preparation for covering.
Do not significantly modify the shape of the airfoil as you sand.

© 2007 Stevens AeroModel. Page 20 of 33
Ailerons:
1. Assemble two (2) ailerons as illustrated below from 1/8” balsa parts A1, A2, A3, A4, and A5. Use the plan sheet
to reference part locations. The 1/8” balsa sheet labeled “SHAFT-04/12” contains the skinny vertical stick A6,
and the long “Aileron Diagonal” sticks.
2. With the balsa ailerons complete use the carbon flat bar stock you previously cut (Page 7, step 2 of “Tail
Feathers” instruction) and bond this to the aileron trailing edge using the same method described for the tail
feather assembly.
Hard Points
1. Use the plan sheet to reference the location and sizing of both 1/8” hardwood wing retention dowels. Sand a
chamfer or round the edges of the dowels. With constant pressure, and a gentle twisting motion, work the
dowels through the holes in the fuselage sides. Remove dowels and harden holes with Thin CA.
2. Do the same with the 3/16” diameter hardwood dowel. Round the ends, test fit, remove, and harden holes with
Thin CA.
3. The photo below illustrates how the landing gear is banded to each side of the 3/16” dowel hard point. The
method for landing gear attachment is as follows: Start rubber band around 3/16” dowel then wrap around the
top loop of the landing gear and back around top of dowel – repeat so that you have a minimum of 4 wraps of
rubber band around the landing gear loop and dowel then place the end loop of the rubber band over the 3/16”
dowel. Add more loops or increase rubber band gauge to reduce shock absorption of landing gear assembly.