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Posted by StayQuiet | Mar 11, 2017 @ 07:26 AM | 841 Views
In my last blog post, I was getting ready to start the build of the Hobo control line model. Plans are complete for both the built-up fuselage (as per the original) and a profile fuselage version. Both versions have been modified to use electric power. If anyone would like a set of cut sheets to have a laser cut short kit made, please send me a private message and I can get them out to you. (The original plans and build article, which you'll need, can be ordered from the AMA.)

So, why have I decided not to go ahead with the build? Well, I've found, and joined, a different RC club with a good field, and (more importantly) a six year lease on the land. I'm still in 'building mode', so I downloaded a set of plans for the RCM Advanced Trainer II, and will be working off those to re-draw an electric powered version. I do like to make some small changes, mostly to accommodate the electric conversion, but also to the wing mounting system, where the 'cabin' area of the fuselage becomes part of the wing structure. I also plan to add flaps.

Once all the CAD work is complete, and I have my laser cut short kit in hand (along with all my other components required) I'll do my best to document and photograph the steps in a build log, similar to the one I did for the Tigercub. I hope I can inspire a few people to try their hand at building, and my design philosophy (tab and slot construction) should make the process relatively easy, even for a first time builder.
Posted by StayQuiet | Jan 02, 2017 @ 08:58 AM | 1,165 Views
I haven't been doing much flying lately, meaning I haven't been building a lot. (I usually build to replace what I crash!)

Our club is losing the RC field in 2017, and the search for a new, suitable site hasn't been going very well. I can still fly the Tigercub at the local park, but my larger planes have become hangar queens.

Going back to my roots - control line. I put together a Brodak "Flying Clown" kit (electric power option, of course) and have been flying that at the park. It's good, because it doesn't take a lot of sky. I wanted to scratch build something, but knowing very little about modern CL design, I purchased a set of plans from the AMA for the "Hobo", which was featured in the August 2012 Model Aviation magazine.

When the plans arrived, I used the basic shape and layout to begin designing the ship in CAD. I modified the plans for electric power, and made a few changes in the design of the wing to simplify the construction. Just for fun, I also drew up a profile fuselage version (the original is built up). Still haven't decided on which version to build yet, but the profile version will definitely be less expensive, quicker to build, and won't generate as many tears should it have an unfortunate meeting with terra firma.

Plans are complete (all detail is not shown in the attachments.) Just waiting for all the holiday bills to come in to be paid off before I can even think about having a short kit laser cut, and getting all the necessary power components (motor, battery, ESC, and timer) purchased to start the build.
Posted by StayQuiet | Jan 26, 2016 @ 01:37 PM | 2,901 Views
Final graphics have been created and applied. Many thanks to my wonderful wife and her crafting machine talents!

Does it fly? Oh, yeah!
Tigercub Flight at Van Du Mar Park 2 6 16 (2 min 20 sec)

Posted by StayQuiet | Jan 26, 2016 @ 10:22 AM | 2,873 Views
Temporarily install the wing with landing gear. Install the nose wheel gear. The nose gear wire will have to be trimmed on top to obtain the correct 'stance' when the plane is on the ground. The steering arm will have to be cut shorter to fit inside the fuselage.

The nose gear can now be installed. Install the radio receiver, ESC, (use velcro) and motor (use 4-40 cap screws) and connect everything up (no propeller!) Check the operation and direction of the elevator, rudder/nose gear, aileron servos, and motor direction. If using the motor and ESC from the prototype, connect black to black, yellow to red, and red to yellow. Once satisfied with all connections, measure and cut sections of 3/32" balsa to cover the cockpit top area, and the lower fuselage from the wing opening to the end of the doublers. Cut out the opening for the nose gear.

Sand the fuselage smooth, rounding the edges (not by the wing saddle or battery hatch opening). When done, the fuselage can be covered with the covering of your choice. NOTE: do not cover the rear bottom of the fuselage yet! Check the balance of the model first. Balance range is 57-71 mm back from the leading edge. I set the starting balance at 60mm and had to add 1/4 ounce to the tail to obtain the correct CoG. Adjust the battery position first to get it as close as possible.
Posted by StayQuiet | Jan 25, 2016 @ 05:59 PM | 2,686 Views
Servos finally arrived. Servos are installed in the servo tray using the supplied hardware (grommets and arms). Measure and cut the outer sleeves of the control rods to the elevator and rudder. I use 1/16" threaded ends with a short piece of 1/16" music wire soldered in on the servo ends. Using a drill, wind the threaded end into the inner control rod, then put a "Z" bend in the wire. Slide the inner rods through the sleeves, measure and cut for threaded snap links on the control surface ends to allow for adjustment.

For the nose gear, I used a ball link on the servo end, and a Quik-Link on the steering arm. I had to drill a hole in the battery tray above the Quik-Link to access the allen bolt for adjustment. When running the linkage for the nose gear and rudder, make certain that when the rudder turns right, the nose wheel turns right! (Don't laugh, I messed that up on my very first kit build.) Measure and cut the sleeve and cable. Use epoxy to hold the sleeves in place, and add additional supports for the elevator and rudder sleeves out of scrap 1/8" balsa glued to the former.
Posted by StayQuiet | Jan 16, 2016 @ 06:53 AM | 2,680 Views
I believe all the errors have been corrected in the CAD files.

1) motor mounting holes have been corrected
2) nose gear steering block mounting holes have been corrected
3) fuselage sides updated to include control rod exit slots
4) hatch magnet retainers added
5) motor cover nose added
6) dihedral set-back gauge added
7) fuselage doublers modified to allow more room for steering arm
8) former A modified to retain nose gear cable sleeve
9) correct number of wing ribs on sheet
Posted by StayQuiet | Jan 15, 2016 @ 10:42 AM | 2,891 Views
Sand the leading edge to a smooth, rounded shape. Sand the top and bottom sheeting, wingtips, and trailing edge extensions smooth.

Using the covering of your choice, cover the aileron mount plates. Make certain you are making a left and right plate! The plates should install with the control arm slot outboard and forward in the wing. Install the HS-85BB servos using the included mounts, 4-40 X 1/4” socket head screws, and 4-40 nuts (or locking nuts). Apply a drop of thread lock to the nuts if locking nuts are not used.

Position the aileron servo plates in place, and drill four pilot holes in the mounting blocks. Temporarily install using #2 X 3/8” button head sheet metal screws. Remove after drilling and mounting.

Measure and cut the aileron stock according to the plans. Mark the centerlines of the trailing edge of the wing, and leading edge of the ailerons. Mark three areas of each aileron and wing for CA hinges, and cut the hinge slots. The leading edge of the ailerons should be tapered to allow movement.

You can now apply covering to the lower part of the wing. Follow the instructions for whatever covering you choose. Cut out the openings for the wing bolt holes, land gear mounting slots, aileron openings, and install the aileron servos / mounts. Tape the servo connector to the cardboard guide and bring it through the slot on the upper part of the wing.

Bend the main landing gear to the template provided on the plans. Both landing gear wires must be...Continue Reading
Posted by StayQuiet | Jan 14, 2016 @ 04:08 PM | 3,851 Views
Apply the forward sheeting from the leading edge to midway on the lower spar in the same manner as the top wing.

Cut two narrow strips of thin, non-corrugated cardboard long about 10” long. Slide them through the slots in the ribs from the aileron mounting position and up through the slots cut in the upper center wing sheeting. This will allow easier installation of the servo leads later on.

Sheet the center bottom of the wing.

Install 1/16” X Ό” wide cap strips on the ribs. IMPORTANT! Cap strips should be even with the rib at the aileron mount opening to allow room for the aileron mount plate. Install the outermost first. Add a piece of ‘filler’ strip on the main spar from that cap strip to the center sheeting. Add a second cap strip on the inboard ribs, cutting out a notch for the landing gear block.

Install a rubber band around the fuselage behind the wing saddle. Install the wing and hold it in place with the rubber band, around the extensions. Support the wingtips on two even blocks (about 1” tall) and add enough weight on the nose to lift the tail. Measure from the outer tips of the horizontal stab to the surface on both sides, which should be equal. If not, remove the wing and lightly sand the wing saddle area of the fuselage on the high side. When correct, check to see the wing sits square to the fuselage by measuring from each wingtip to the outer tips of the horizontal stab. Adjust as needed until the measurements are equal.

Using a long 5/32” drill bit, drill down through the 10-32 blind nuts (from the fuselage side) through the wing. Remove the wing and enlarge the holes with a 3/16” or 13/64” drill bit. Harden the hole with thin CA and drill again when dry. Glue the 1/16” ply reinforcing discs in place. Use 1” long nylon wing bolts to secure the wing to the fuselage.
Posted by StayQuiet | Jan 14, 2016 @ 10:29 AM | 3,909 Views
Cut 3/32” X 3” balsa sheets into 8 sections 7/8” long, vertical to the grain. Fit and glue each section to the front of the spars, 4 per wing half, starting from the center (not the dihedral brace).

Measure and cut 1/16” X 3” sheets to form sheeting on the upper front of the wing. Sheets should go from the ‘lip’ of the leading edge to approximately half way across the upper spar. Glue into place.

Measure and cut 1/16” X 4” sheet to center sheet the wing from the middle to the inner rib supporting the landing gear block. Glue into place.

Cut Ό” wide strips of 1/16” balsa. Measure, cut, and glue in place as cap strips over the wing ribs.

EDIT: Apply a section of pinking tape across the center seam of the sheeting. Either used thinned epoxy and work it through the tape with a squeegee, or soak with thin CA (Note: well ventilated area!) Mark and cut out two openings in the center of the sheeting in line with the slots in the wing ribs to allow the aileron leads to exit. (No photos of this - I forgot to do it on the prototype build and had to add it later, which was much more difficult.)
Posted by StayQuiet | Jan 14, 2016 @ 07:29 AM | 3,239 Views
Trial fit the two wing halves together, using the 1/8” ply main and trailing edge dihedral braces (Do NOT glue in yet!) The dihedral braces should line up with the spars and trailing edge, and fit tightly between the two inner ribs. IMPORTANT - The main brace installs to the REAR of the spar! Sand if necessary to get the gaps to a minimum, and check to see that the leading edge is straight across. When satisfied with the fit, install the braces using 30 minute epoxy. Apply epoxy to the joint behind the trailing edge as well. Do NOT glue the leading edge!

Cut a section of Ό” dowel approximately 2-3/16” long. Round one end. Check the leading edge holes (made earlier). They may have to be re-drilled slightly to install the dowel.

Install the two 1/8” lite ply wing dowel support ribs in the center of the wing. Slide each on in between the spars, then even with the wing joint. Glue the two ribs together. Slide the dowel in place and epoxy in.

Glue the two 1/8” balsa rear half ribs in place.
Posted by StayQuiet | Jan 13, 2016 @ 04:43 PM | 2,924 Views
Measure and cut a section of the grooved landing gear block to fit into the block mounting ribs. Drill a 1/8” diameter hole, 3/16” from one end. Use a file or Dremel to “radius” the wood to match the bend of the landing gear wire (to be made later). Epoxy the landing gear block in place, making sure the hole for the wire is INBOARD on the wing.

Snap off the build tabs and sand any small remnants smooth.

Sand the trailing edge top (the Ό” square balsa) to match the angle of the ribs. Cut another 1” wide section of 1/16” balsa and glue it to the top of the trailing edge and ribs.

Sand the back of the trailing edge so that it is square to an imaginary line through the middle of the rib as viewed from the side.

Cut two pieces of Ό” square basswood (use the leftover pieces from the wing spars) approximately 3 Ό” long. Epoxy them in place on the lower edge of the wing, inside the ribs as shown on the plan. These will act as the aileron plate mounts. The front edge should be even with the spar, and the rear should fit under the 1/16” balsa sheeting.

Glue two 1/8” balsa wingtips together. Cut a piece of aileron stock to make up the outer wing extension as shown on the plans. Make sure the taper of the aileron stock matches the angles of the wing ribs, and glue in place. Use balsa filler if needed. Glue the wingtips in place from the leading edge to the end of the wing extension. Glue two wingtip supports (small triangles made from scrap stock) in place. When dry,...Continue Reading
Posted by StayQuiet | Jan 13, 2016 @ 01:47 PM | 3,305 Views
Before removing the non-tabbed wing ribs from the 3/32” X 6” X 24” laser cut balsa sheet, mark the top of the ribs with a marker (a dot will do). Even though this is a NACA 0015 (symmetrical) airfoil, the ribs are non-symmetrical. The angle at the end of the ribs determines top and bottom. Installing one upside down will mean the trailing edge will not fit properly. Note: extra ribs are provided in case you break one.

The wing is built in two halves. Cut a length of Ό” square basswood spar to the plans to start building one half, and cross pin it into place. Using pins to hold the build tabs down, install four of the tabbed build ribs (one outermost near wingtip, skip a rib, then place a second, skip a rib and then place a third, skip two ribs and place the fourth. The fourth build rib should be the rib just away from the center of the wing (NOT at the center where the dowel is!) Make sure each rib is square and glue to the spar.

Cut a Ό” square balsa stick to the length of the trailing edge on the plans. Cut a 1” wide piece of 1/16” balsa to the same length. Glue the Ό” square balsa to the edge of the 1/16” balsa using thin CA. Install the trailing edge assembly to the underside of the four build tab ribs. The remaining “full” ribs can now be glued into place.

Locate and remove three of the main landing gear block half ribs from the 1/8” lite ply sheet. Glue into place as per the plans.

Cut a length of 5/16” square balsa to the leading edge on the plans. Make...Continue Reading
Posted by StayQuiet | Jan 13, 2016 @ 09:17 AM | 2,988 Views
Assemble the horizontal and vertical stabilizers. Using 30 minute epoxy, glue the vertical stabilizer into the slot of the horizontal stabilizer. Check to make sure the vertical stab is square, both horizontally and vertically.

Check the fit of the tail assembly on the fuselage. There is a little “wiggle” in the slot in the rear fuse top, so verify that the horizontal stabilizer is square. I use a piece of 1/8” square balsa, measuring from the top opening of the battery hatch opening to the rear of the end tips of the stab. Adjust as needed to equalize the measurement on both sides. Check the horizontal stab for level by holding the fuse down on a flat surface (your building board) and measuring the height at the outer ends of the stab rear. You may need to lightly sand the area of the fuselage where the stabilizer sits to accomplish this. Once satisified, the tail feathers can be glued in place using 30 minute epoxy. Double check alignment and level, and pin the pieces in place while the epoxy cures.
Posted by StayQuiet | Jan 13, 2016 @ 08:08 AM | 3,063 Views
The motor cover is assembled from the two 1/8” balsa and two 1/8” lite ply motor cover sides. Make a left and right pair! Insert 4-40 blind nuts into the lite ply parts, and then glue them to the balsa sides.

Glue the motor cover nose piece in place. (Note: photos show prototype. Updated CAD files will have this laser cut.) Cut and glue 1/8” balsa pieces from scrap to fit across back (approximately 46mm X 20mm) and then cut, sand, and fit two more pieces to form the curved area in front. When glue dries, sand into a rounded shape.

The motor cover should slide into the nose of the fuselage, and is secured with four nylon 4-40 screws. This allows you to access or remove the motor in the future, if required.
Posted by StayQuiet | Jan 13, 2016 @ 05:08 AM | 2,977 Views
Locate and remove two battery hatch sides and one battery hatch top (on the same 1/8” balsa sheet as the fuselage sides – one per sheet) Note: there is a battery hatch top on each piece, but only one is required. Glue the sides to the top – it doesn’t matter which way the top is oriented, just make sure the taller ends of the sides match up. Use some balsa triangle stock to reinforce the joint. The triangle stock should be cut and installed from the front of the hatch to approximately the rear of the rearmost interlocking tab on the top. This will allow you to install the magnets later.

Locate and remove the three hatch tabs from the 1/8” lite ply sheet. Set two of the tabs on the fuselage, up against the top of the doubler where the battery hatch will mount, and draw a line. Glue each tab to the inside of the hatch sides, with the line lined up or slightly above the lower edge. Glue the third tab to the front of the hatch (the lower side end).

Locate and remove the two Battery Hatch Magnet Retainers from the 1/8” lite ply sheet. (Note: these are new laser cut parts not on the prototype.) Glue two Ό” X 1/8” magnets into each retainer. Make sure the magnets will attract each other when placed near the other retainer! Glue the retainers and magnets to a section of 3/8” triangle balsa stock, cut to the same width, and glue one to the rear of the hatch.

Cut two pieces of 1/8” balsa, one to fit from the motor bulkhead to the start of the hatch opening, and one to fit from the rear of the hatch opening to the start of the cockpit curve in the fuselage sides. (Note: these pieces should fit snugly between the balsa fuselage sides.) Glue the second magnet retainer and triangle stock to the rear piece, and glue both pieces in place. When dry, the tab of the battery hatch should slide under the front piece, the side tabs guide the hatch into the fuselage, and the magnets hold it in place.

Since no tools are required to remove the battery hatch, the inside is a good place to put your FAA registration number.
Posted by StayQuiet | Jan 13, 2016 @ 04:59 AM | 2,932 Views
Locate Former D on the 1/8” lite ply laser cut sheet. Mark the top of the former with a pencil – the top of the former is closest to where Former A was on the sheet. Remove Formers C and D. Using the vertical view plans as a guide, insert Formers C and D tabs into their slots, and draw the rear of the fuselage together. NOTE – a small section of 1/8” square balsa is glued in place between the two fuselage halves at the rear joint. Once assured that everything is lined up, used medium CA to glue Formers C and D in place.

Locate and remove the rear fuselage top and bottom from the 3/32” X 4” X 24” balsa laser cut sheet. Slide the top into position from the front. Temporarily locate the horizontal and vertical stab assemblies (NO GLUE!) on the fuselage. Make certain the tab of the dorsal fin drops into the rear fuselage top, and the rudder will still line up with the vertical fin and rear of the fuselage. When satisfied with the position (HINT – the front of the top piece should be approximately half way over the top of Former B) use rubber bands to squeeze the fuselage sides flush with the top, remove the vertical and horizontal stabilizers, and apply thin CA to glue in place.

Install the lower rear fuselage. The front part of the lower rear fuselage should be even with the front of Former B. Again, rubber bands will be needed to squeeze in the sides before gluing in place. Any gaps near the rear should be filled with balsa putty.
Posted by StayQuiet | Jan 12, 2016 @ 02:12 PM | 2,908 Views
Remove the battery tray and servo mount plate from the 1/8” lite ply sheet. Remove wing mount blocks A and B, and the wing dowel reinforcing disc from the 1/8” ply sheet.

The holes in the motor mount and nose gear mount plates are deliberately undersized. Drill them out to the proper diameter to match the 4-40 blind nuts you are using. Install the blind nuts. You may have to file the edges of the blind nuts on the top of the nose gear mount flush with the top of the mount. (NOTE: there is no picture of this provided. My prototype part was designed with an error and I had to ‘fudge’ a fix. It has been corrected in the new CAD files.) Install the nose gear steering block with 4-40 X 3/8” cap screws.

Glue wing mount blocks A and B together, lining up the holes for 10-32 blind nuts, and install the nuts. Blind nut must be installed from block A (the smaller block) side!

Glue the wing dowel reinforcing disc to former A, using a Ό” diameter dowel to position it. DO NOT GLUE IN THE DOWEL!

Glue the motor mount in place (epoxy is preferred). Blind nut flanges face rearward! There is a small amount of down thrust designed into the mount. Use a square, or square block, to keep the motor mount square to the fuselage side and doubler. Allow to dry.

The tab on the rear of the battery tray fits into a slot in Former A. Apply wood glue to the rear of the battery tray, and the side of the tray and Former A that will contact the fuselage doubler. Make certain the wing...Continue Reading
Posted by StayQuiet | Jan 12, 2016 @ 10:04 AM | 3,117 Views
Remove the fuselage sides and canopy top supports from the 1/8” X 6” X 36” laser cut sheet. Lay out the two 1/8” balsa fuselage sides. MAKE SURE TO MAKE A LEFT AND RIGHT SIDE! Remove the motor and nose gear mounts from the 1/8” ply sheet, and fuselage doublers and formers A and B from the 1/8” lite ply sheet.

Spread a thin layer of wood glue onto one side of a fuselage doubler (preferably the side that goes against the fuselage side!) Temporarily use the motor and nose gear mount, and formers A and B tabs to position the doubler in place. The doubler should fit so that the wing opening edges are flush with each other. Apply a drop of thin CA to a few areas around the doubler to “tack” it in place, then remove the mounts and formers. Apply a weight evenly over the doubler and allow to dry completely. Repeat on the other fuselage half.

Use two scrap pieces of 3/32” thick balsa to position the canopy top support in place. Glue the support into place. Repeat on the other fuselage side,
Posted by StayQuiet | Jan 12, 2016 @ 07:55 AM | 2,812 Views
All laser cut parts for this step are on the 3/16” X 6” X24” balsa sheet.

Locate and carefully cut out the laser cut horizontal stabilizer parts (2 leading edges, 1 trailing edge, 1 center piece, 1 leading edge support, 2 tips.) Lay them out over the plans, pin and glue in place. Measure and cut 1/8” X 3/16” balsa trusses, and glue them into place.

Remove the horizontal stabilizer from the plans. Locate and cut out the elevator halves and pin them in place over plans. Use a straightedge to assure they are lined up on the leading edge. Measure and cut a section of 3/16” square basswood to connect the two halves. Sand the leading edge of this piece into a rounded shape, and then glue into place (use epoxy here!) Measure and cut two 1/8” X 3/16” balsa pieces and glue into the elevator slots.

The vertical stabilizer / dorsal fin and rudder are built in much the same way.
Posted by StayQuiet | Jan 11, 2016 @ 05:22 PM | 3,004 Views
UPS delivered the laser cut parts and wood stock ordered from National Balsa late this evening. All parts arrived in excellent condition, well packaged and complete.

Note: the 1/16" ply parts sheet is not shown. I have used the aileron mount plates and wing bolt reinforcements shown on the sheet in the CAD files in other designs, and had extra parts made to utilize more of the sheet. It was not necessary to have them re-cut for this build.

EDIT: due to changes and additions to the CAD files, your laser cut sheets may not look exactly like those shown.