Pipsqueak re-start- Frank's big 23" span pylon racer (.049 size)

[Frank v B]

This is a Covid Re-start.  Built the fuse years ago and installed  a 28mm in runner which will be too big.  Will downsize to a 24mm in runner.  Bought one for $5.00 at the Kitchener Swap meet.  The plans were published in Radio Control modeller waaayyy back in 1967.
This plane has ailerons and elevator, rudder and.... it has wheels!  The instructions caution you not to hand launch it unless you have a 40 mph headwind.  This could be a one-flight beauty.

Work completed before the re-start-:
- fuse built and sanded
- motor installed
- all balsa parts cut out and ready to assemble (Stab, elevators, rudder, fin, ribs)

Last night I found the plans, found the stick balsa and started the wing. Just pinned the trailing edge together.
The photo shows the state it was in this morning.

This will have the Orangeville EF-1 guys shaking in their boots.... with laughter.

Frank

[sihinch]

That looks great, Frank!  Wow.

[Frank v B]

Started the wing.

Photo 37- stack-sanded the ribs and marked the top spar groove with a magic marker so they all orient the same way.
Photo 38- placed 4 ribs on the bottom main spar and glued them in place and let it dry.
Photo 39- tail feathers cut out of balsa.

Frank

[Frank v B]

More wing work:

Photo 47- ready for the top spar.
Photo 48- installed the top spar and about to add a false leading edge.  I slipped about 20 rubber bands on it, added glue to the front of each rib and installed it.  The rubber bands were stretched to hold it in place.
Photo 49- leading edge in place with all the rubber bands stretched.

Frank

[Frank v B]

The wing continued.

Two adjustments:

The trailing edge was in 2 parts to handle the ailerons.  The 1/8" thick balsa at the back end of the ribs was higher than trailing edge stock.  This had to be shaved down to be flush with the trailing edge stock.

Photo 50- Put masking tape on the ribs and trailing edge.  This is to protect the ribs.  Then tried the razor plane.  Mixed results.
Photo 51- Try 2- with Roger's DuraGrit  sanding bar.  WOW! much faster and easier.
Photo 52- Adding the main leading edge ahead of the thinner false leading edge.  It is pinned to the board to keep the leading edge straight.

Frank

[Frank v B]

Motor choice:

The motor I slipped in was a 28mm out-runner helicopter, high KV motor (Photo 54).  The motor I wanted to change it to was a 24mm Ammo inrunner (photo 53) to save weight.

Now I am totally confussed.  The 28mm motor weighs 2.5 oz, the 24mm in-runner weighs 3.5oz.  Counter-intuitive.

Looks like I will be keeping the larger but lighter motor.  Weight is an issue with such a small wing.  The output is about equal (300 plus watts)

Frank

[Frank v B]

- Making the elevator halves.  I keep them together until the hardwood joiner is glued in and dry.  See photo 58.  After the glue dries, I will separate them.
- installing the bottom fuse at the back 1/3 only until the servos are installed and the pushrod slots are cut.  See photo 59


Note, there is a hatch on the bottom of the nose held in place with 2 magnets.  The entire fuse bottom behind the leading edge of the wing is solid.  Made the wing removable.  the plans shows it glued in place.

Frank

[Frank v B]

Electronics decision:

1) Opted for two aileron servos glued into the wing.  The other options were bellcranks, wire inside a sleeve or torque rods but each would require cutting into ribs and fussy alignments.
Before installing them in the wing there are 3 things:
            i) test that the servos work.  Done via a GreatHobbies Servo tester.
            ii) center the servo arms. Done with the tester.  It as a "center" button.
            iii) put dental floss on any servo cases not held together with 4 screws. Two wraps of dental floss and one drop of glue on the knot.  I have had them come apart!!

2) Two HS55's for rudder and aileron.  They have 4 screws so no flossing required.
Will post a photo once I figure out why it is refusing to attach. (insubordination?, Hoffer influence?)

Frank

[piker]

Very cool plane, Frank!

[Frank v B]

Photo 82- wing servos installed.  Note the details  i) servos glued in place  They will last longer than the plane, ii) servo extensions installed.  The connections are wrapped with dental floss and one drop of glue.  iii) cut slots in the bottom ribs, slipped the wire in place, added 1/16 balsa to close the gap with a drop of glue.  After it dries I will cut it and sand it flush. iv) the LE wing dowels.  Pointed skewers.  I slide them back, put ink on the tip, hold the wing in place and slide the dowel forward.  It marks where to drill the hole in the fuse former.  Once done, I put in new stronger dowels.

Photo 83- The servo rails in place for the elevator and rudder servo.  Screws can now be installed.  The two pins hold the tri-stock in place on the landing gear mount.

Frank

[Frank v B]

All the glue joints cured overnight.  The first time the plane has been assembled.

Looks weird.  The wing seems short for the fuse length but then this is a minimal pylon racer.  Have you ever seen a photo of the full size Cassutt Formula 1 Racer with its small wing (last photo)?

On take-off, V1 will probably be close to terminal velocity.   

Frank

[piker]

Cute as a button!

[Frank v B]

Thanks Piker!

Covering: a step by step :"how-to cover a model airplane".  Use this as notes so you can concentrate on Michaels on-line seminar later on.
Note: Everyone has their own way of doing things.  My way is just one option.

Step 1- cover the corners where there have to be cuts in the covering (photos 71,72,73)

[Frank v B]

Covering the wing.

Guide:
- do the bottom of the wing first.  One half at a time.  If you have a true flat bottom wing on a small plane it can be one piece.  The reason the bottom is done first is because the edge from the top covering wraps around the bottom.  You won't see the edge.
- Peel the backing film and lay the covering on the wing half.
- Tack the corners. touch the heat gun at at the 4 corners to keep it in place.  I touch the center trailing edge first to adhere the covering about the size of a dime, then lightly pull the film on the outboard trailing edge and tack it down with heat.  Now the film is in place and won't move.  Lightly pull and tack down the other two corners.
- do the aileron area- Cut two 45 degree angles in the covering (photo 74) and attach it to the trailing edge, then the sides (photo 75).  Now you know why the first step was to cover the inside corners.
- attach the entire perimeter but do the tip last.
- cover the tip. Hold the wingtip covering between your thumb and forefinger.  Pull the covering until the wing is at an angle.  You are using gravity to stretch the film (photo 78).  While the covering is not touching the wood, lightly heat the covering so it stretches, then adhere it to the wood.  In most cases the tip will be wrinkle-free.
- cut the excess covering. A trick to cutting.  I use a brand new #11 blade and start about half inch from one end (photo 76).  Cut to the end.  Then the second cut to the left (photo 77) and remove it.  The reason: this way you do not have to hold it while cutting accurately.  A lot faster and more accurate than starting at an edge.

Important.  Do not stretch the covering until the entire wing is covered.  The reason: On a wing, you need to handle both sides (top and bottom) at the same time or the structure can and will warp.  The lighter the structure, the more important this is.

Do the other 3 panels in the same way.

Declare victory!!

Frank

[Frank v B]

The other 3 panels.

The only extra trick to point out is when finishing the wingtip covering.  Photo 80 shows the 1/4" overlap of the top covering. I put about 10 cuts in the radius.  They are visible in the photo.  Then run the covering iron over it from back to front (trailing edge to leading edge).  This is so that the seams are overlapping downwind so an edge can't be caught by the wind and be peeled back.

Photos 81 (top of wing) and 82 (bottom of wing) show the finished wing before heat shrinking the film.

Frank