AMA CHARTER 3467

Cloud Dancer Article

Cloud Dancer Full Size Plans

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DV

The free Cloud Dancer plan and article were downloaded off Outerzone.co.uk, but plans can also be found on AeroFred.com, which has several versions of the Cloud Dance ranging from 40" to 86" wingspans.  There also is a laser short kit for the larger Cloud Dancer 120 available for purchase on bulsaworkbench.com.

The Cloud Dancer I'm going to build was designed by Fred Reese, and the article is from a June 1993 edition of Radio Control Modeler (RCM). This 60 size version has a wingspan of 73" with a total wing area of 850 sq. inches, which will result in a light wing loading of approx. 17 oz. per sq. in.  The overall fuselage length is 57", and is designed for a .40 - .60 two stroke.
I will be installing a Thunder Tiger .61 that my father used many years ago.

First step in this build was to print out a copy of the full size plan on my Canon printer using the "poster" settings, and then putting all the pages together for an overall 77" x 51" plan (will send you a picture).  Given the plan only has the right wing and right horizontal stab drawn, I inverted the plan file vertically to get a left wing and stab, and that copy of the plan is cut up to get the patters for all the ribs, formers, fuselage sides, etc.
You can also get the plan printed out at FedEx for around $25 a copy.
Having the full size plan, I then go thru and determine all the materials I'll need to make the build.  Any balsa sticks and sheets, basswood, or plywood I'll need is ordered from Balsa USA.

I plan to use my magnetic build board and fixtures for this plan as I think all the major sections will fit on the 48" board.  If not, I'll resort to the old wood build board with pins.

The Cloud Dancer is a fairly simple build for anyone with some basic woodworking skills, and would make a good first scratch build project.  The build is started by cutting out the templates in the plan for all the wing ribs W-1 thru W-13).  With a double taper wing, you will only have two of each rib that are the same, so trace a given rib pattern on the 1/16" x 3" sheet balsa, and then put two pieces of balsa together using double sided scotch tape (small pieces at each end of the (rib) to cut both ribs out at the same time.  I use a table band saw to cut out the rough rib shape and the various spar notches, and then a table disk sander to sand down to the final shape, just removing the traced lines.  I then use a scrap piece of spar material to fit check each spar notch. Do the same for the several ribs that call for 1/8" lite plywood.

Since the airfoil is semi-symmetrical with a flat bottom, the wing sections can be built directly on the plans without having to use a wing jig. I'm using my magnetic build board for this project. The one big advantage of the magnetic board is it allows me to do a dry fit (no glue) buildup of the entire wing section. The build can also be accomplished using the standard wood table board with pins to hold everything together. As I'm cutting out each set of ribs, I test fit and adjust each to fit over the lower spar and trailing edge, holding each in place with the various magnetic board fixtures I've built. This wing design is called a boxed "D", because the wing surface is covered with 1/16" sheet balsa from the centerline of each spar forward to the leading edge material, along with shear webs between the spars, making a "D". This results in a strong, but very light wing structure. The large rib on the left has a cutout for the aileron servo and rails, and is held at the correct angle using a dihedral gauge so that when the wing wings sections are glued together, the two large end ribs will fit flat together with each wing tip raised 2.5" at the wingtips. I will use 3/32" balsa sheet for the vertical gain shear webs between all the ribs and the lower/upper spars. While many builders use CA for assembly, being an old man that moves pretty slow, I prefer to use a premium wood glue for a majority of the assembly, and two part epoxy for the high stress areas (like landing gear blocks, firewall install, wing sections joint, horizontal tail to fuselage join, etc.).

In this picture, all the left wing ribs have been glued in place; the 3/32" vertical grain balsa sheer webs glued between each rib; the balsa top spar, 1/4" square leading edge, and trailing edge are all then glued to the ribs.  Ribs W-2, W-2A, W-2B, W-3, W-4 and W-4A are all 1/8" light ply and have notches cut in the bottom to install the main landing gear block.  Once this all dries, the wing can be removed from the board to sand anywhere needed to make a smooth transition between ribs, spar, leading and trailing edges.  Then a 1/16" x 1" balsa strip is glued along the top edge of the entire trailing edge, and 1/16" x 1/4" balsa cap strips are glued along the top of ribs W-4 thru W-13 from the center of the top spar back to the piece just installed.  Next, 1/16" x 3" balsa sheeting is used to cover the area over ribs W-1 thru W-3 from the center of the top spar aft.  Unlike in the build article, DO NOT install the 1/16" balsa sheeting from the top spar forward to the leading edge yet.

After all that dries the wing can be turned over (bottom side up) to install the left MLG block and supporting structure from ribs W-2 thru W-4. After any required sanding, repeat the install of the 1/16" x 1" strip along the trailing edge, the 1/16" x 1/4" rib cap strips, and the 1/16" sheeting to cover the area over ribs W-1 thru W-3 from the center of the top spar aft.  Now use 1/16" balsa sheeting to cover the area over all the ribs from the center of the top spar forward over the leading edge.  When that all dries you can turn the wing back over (top side up) to see the MLG block assembly.  I've not completed a scratch build yet without making some kind of changes, and this one is no exception.  While the plan and build article does not call for it, I used fiberglass cloth and glass resin to strengthen all the joints between the MLG block and ribs W-2 thru W-4.  I'm known for carrier deck landings, so this will help to ensure my MLG gear structure stays in place.

  Builders tip - now is the time to use a pin to push thru the 1/16" balsa sheeting at each end of the MLG block center channel so you can easily find where to remove the 1/16" sheeting over that channel.  Also, use a 3/16" drill bit and run it down thru the vertical MLG end block and the 1/16" sheeting on the bottom side.  With all this done, again use 1/16" balsa sheeting to cover the area over all the ribs from the center of the top spar forward over the leading edge. This makes the wing "D" structure I mentioned earlier.

Double Trouble

Larry says "She has a wing span of 36.5", overall length of 38", and is powered by an O.S. 46LA.  A very simple build, and should turn out to be an interesting aerobatic biplane."

Magnetic Build Board by Larry Nieman

The Results: A scratch built 1935 Aeronca C-3. Six foot wingspan and powered by an OS .35 2-cycle.

Airfield Models

Lots of good info here, and is where I got the info I needed to make my magnetic building board and all the fixtures.

Larry

Here you can see the two fuselage sides in build-up over the plan.  These are built using balsa sheeting that is then covered on the inside with a plywood doubler for the strength needed in the wing area and the nose.  You can also see the firewall laying on the bench with all motor mount and nose landing gear assembly blind nuts installed.  Note also the plywood fuselage formers that go between the two sides.  Large balsa blocks are required at the nose because they are then sanded down on the outside to obtain the streamline shape required to match the prop spinner diameter.  Other large balsa blocks are used along the top of the fuselage. 

The second picture shows the fuselage fully assembled with engine cut-out and the outside sanded down to get the required overall shape needed. A large hatch is placed in the bottom of the fuselage to obtain access to all the gear, fuel tanks, and wing mounting screws.

Model Plans Picture:  These free plans were downloaded from Aerofred.com.  This is a great web site if you are interested in doing some scratch building.  They have over 22,000 plans.

General characteristics
·         Crew: 1
·         Capacity: 2
·         Length: 7.9 m (26 ft)
·         Wingspan: 12 m (40 ft)
·         Wing area: 43.9 m2 (473 sq ft)
·         Gross weight: 549 kg (1,210 lb)
·         Powerplant: 1 × Gnome 7-cylinder air-cooled radial, 52 kW (70 hp)
Performance
·         Maximum speed: 90 km/h; 49 kn (56 mph)

This is the rudder, in build on the plan, and ready for covering.  Being a canard aircraft, the rudder is at the front of the model, which will make the model look like a plane flying backwards. It is attached to the nose landing gear wire which will be controlled by a small servo near the front of the fuselage (see plan photo) with a NLG steering control arm.  The rudder, and rest of the model, will be covered cover with flat tan UltraCoat.

This is the bottom wing, at initial build on the plan, and as finished except for the wing mounting blocks to be installed once the fuselage is built.  Both wings are under-camber airfoils, which required shims under the front and aft spars during the build-up.  The main spar is a build-up of two full length pieces of basswood with a piece of balsa sandwiched between them.  This is the first model I've built using this design.  The aft spar is one full length basswood piece, with balsa fillers between each rib.
There are a total of 107 individual pieces in this bottom wing.  Main landing gear blocks can be seen between the various ribs.  To be more like the original aircraft, I did not build the wings using an outer dihedral as shown on the plans.  Each wing is 45 inches long.

This is the top wing in work on the plans.  Similar under-camber airfoil and spar contraction as the bottom wing except for the two ailerons, which will be controlled by a single center mounted servo using flexible Gold-N-Cables running inside the wing.  The top wing will have a total of 146 individual cut pieces.

Top wing completed except for center wing mount filler blocks. A single center mounted servo will drive the ailerons thru Gold-N-Cables.

Left:Start of fuselage build over the plans.  I used basswood thru-out the structure, which will increase the weight somewhat, but will also significantly increase the strength of this long stick fuselage.

Right: Fuselage sides where then aligned in a home made jig to keep everything straight and square while the wood glue sets up.

Here you can see the initial test fitting of the rudder, nose landing gear, and the two canards.  Brass tube assemblies go thru the entire length of the rudder and canard surfaces.  The rudder is then glued to the nose landing gear 1/8 hard steel rod, which will be controlled using a standard NLG steering horn inside the fuselage.  The two canards are mounted out on the front of the nose using an assembly of three different size brass tubes to allow pivoting of the entire canard surfaces. Lots of surface area out there, so it will be interesting to see just how sensitive the pitch control will be.  Both canards are controlled using handmade control horns and a pull-pull cable system that comes thru the fuselage sides back by the fuel tank near the CG.  As I indicated earlier, this plane will look like it is flying backwards.  Next comes building the four pull-pull control horns from
1/32 brass sheet covered with 1/32 ply, and final full-up fit checks and CG balancing.

This picture shows the initial test fitting of the two wings to the fuselage.  Between the wings are six fins, and they will eventually be covered, which will make the wing assembly look like an old box kite.  How many of you have made a box kite when you were a kid? They fly great.  While the plans do not call for them, I'm going to install small 90 degree brackets at the back of each wing fin to hold them in place.  The front of each fin fits into a notch cut into the leading edge of each wing.  The main landing gear were bent from 1/8th and 1/16th hard wire, and then finished with basswood which is attached using cord wrapping.

With the major build completed, I then accomplished a full-up fit check of all aircraft assemblies to include engine; fuel tank and lines; aileron, throttle, and canard servos; and all the other hardware.  This step also allowed me to determine the position of the final servo (rudder/steering) and the battery pack to establish a proper CG.  The CG for this aircraft is
5 inches in front of the wing leading edge, which is just forward of the red strap you see around the fuel tank.  Next step is disassembly and start the painting and covering.

Click on the picture to the left to see what Larry has designed to add under the center wing section of the Double Trouble. He calls it the X-20. It's an unpowered glider with elevons and he says he will need someone to fly it back to the runway after he releases it from Double Trouble. Larry I think people will be standing in line for the chance.