While staring at the ceiling (remember, I am bored to tears during re-hab from knee surgery) and reading one of Simon Chapman's British model magazines got an idea that won't go away.
Build a 30" span version of the 1993 free RCM&E plans for the 48" span, .25 size Chili Breeze.
The Chili Breeze was an amazing pattern airplane with a ball-bearing .25 OS in it. It was the first plane that had a 200' vertical from takeoff. It weighed just below 3 pounds.
I have built 4 so far:
- 48" span per plan with an OS 25 ballbearing- The photo shows this plane at TEMAC after putting in a 400 watt electric motor.
- 43" span (90%) with an OS .25 ballbearing to get more power for the weight.
- 54" span (115%) with an OS .45 ballbearing
- at TEMAC- a 48" span per plan with a Power 25 EF1 motor (800 watts!). It disintegrated on a low pass at full speed when the radio glitched (full down!).
Plan
- install an E-Flite inrunner 6 on 3 cells with a 6x4 prop. That puts out about 300 watts. This combo draws 28 amps.
The size makes it a cross between our Nooner Pylon racer (200 watts, 34" span) and the Mini Tarka that I built twice, a 30" bullet but with a shorter fuse. https://outerzone.co.uk/plan_details.asp?ID=10385
Just drew the wing plans to 30" from the 8.5"x11" Outerzone plans.
Frank
ps: before anyone tells me about magnifying printers and printing services.... I am trying to keep busy while not leaving the house.
Wing plans are done:
Printed out the plan and magnified everything 2.96 times to get 30" span.
photo 91- plan on an 8.5" x 11" sheet. All the calculations for the 30" span size
photo 92- the calculation sheet. No, I did not use an abacus. Good thing I have all 10 fingers. ;)
photo 93- the full size wing plan.
Frank
..and the full size fuselage and tail feather drawings done.
F.
Making the ribs on a double-tapered* wing.
Step 1- make a plywood template of the center and tip rib.
Step 2- collect enough rough cut balsa for each of the ribs Photo 80
Step 3- drill 2 holes through the stack for a tight fit for either piano wire or brass tubing. Secure with wheel collars. Photo 81
Step 4- I rough cut the ribs with a #11 blade then sanded it with a sanding block. Total time to carve and sand- 5 minutes.
Step 5- with a razor saw- cut the leading edge, trailing edge and main spar notches. Photo 84
To come:
Step 6- match up rib pairs and trim the larger of the two to match the smaller of the 2 so you have matching ribs.
Go build the wing!
Frank
* Double-tapered means the tip rib is smaller than the root rib in length (chord) and height.
How to build a double tapered wing
Building the first wing half
Note: this airfoil is flat-bottom.
The first two photos are of the trimming the rib pairs the same size. Number them.
step 1- install leading and trailing edges exactly per plan outline.
step 2- install the root and tip ribs- glue in place.
step 3- install bottom main spar. Pin in place so it cannot move.
step 4- divide the open bay measurement by 6 to get equal spacing for the 5 other ribs (2 3/8").
step 5- make the ribs to the size of the opening by trimming the leading and trailing as long as the main spar hole stays in line with the spar.
step 6- glue top main spar in place. Put a weight on it.
Let it cure over dinner.
Frank
Second wing half.
I build the second half off the first half (Photo 92). The first half has been propped up 1" to handle the dihedral angle (Photo 89).
This way there is no problem matching up the leading and trailing edges and the dihedral angle.
Everything butts up perfectly at the center rib. Photo 90 is of wing after the assembly.
F.
NICE CLAMPS!
Gregor,
The clamps are Tomato clamps from Dollarama. They are perfect for balsa because they do not crush it. A dozen for about $1.50. There are two sizes. The only mod- cut off the two nubs on the pads since they will poke into the balsa.
Frank
sheeting one half of the wing.
Note it is pinned down while the glue dries so it will not develop a warp.
F.
Port* wing top sheeting
Did the same to the *left wing half top.
Wanted to do the bottom sheeting of the right wing half first but then I realized:
1) it would not lay flat at the root when doing the left wing.
2) I still have to install the dihedral brace. I do this by cutting into the bottom ribs and installing it. Only then can it be sheeted. Note: this wing has sweep in the main spar per the leading edge so you cannot just glue the dihedral brace to the back of the main spar. You will see soon.
Notice how nothing at the tip lines up (spar, LE, TE, sheeting). See last photo 78
I learned a loooong time ago to trim it with a saw at the end.
1) it allows me to pin the spars in place outside of the tip rib.
2) A single saw cut takes the place of many measurements. Cutting each one the right length takes much more time than one cut, one wrong measurement and getting the balsa stretcher out ;)
Frank
Adding the dihedral brace.
Used a saw to cut the slots. The brace is out of hard balsa. The finished wing will have fibreglass in the center section.
Not visible are the shearwebs* added to the 4 affected bays.
Frank
* vertical grain pieces between the upper and lower spars. Out of 1/16" balsa.
@Frank v B this dihedral brace looks a bit on the short side.
Should it not extend to another rib for more rigidity?
I really like this method of adding the brace, worked fine in the Spitfire to add the L/G.
Have a great building day!
Guy,
Your comment "this dihedral brace looks a bit on the short side. Should it not extend to another rib for more rigidity?" is true if this plane had landing gear. it does not. It has poor man's retracts (hand-launch).
Braces should always be staggered to eliminate stress points. The double spars go full length (10 bays), the shear webs go 4 bays, the dihedral brace goes two plus bays. It has full leading edge sheeting top and bottom and will be glassed in the fuse area but wider than the fuse.
This is a small plane and by the time it is finished it will be overbuilt...or not. The first flight will tell. ;D
The ultimate in this is the old SuperSportster 40 kit. It was a superb flyer. You built two wing halves, butt glued the centre ribs and glass over top all the way around. No brace at all. I did not believe it but it held for 100 flights before I gave it away.
Frank
Glassed the center section with 1/2 ounce cloth and 5 minute epoxy.
This wing will be strong!
installed the ailerons as well.
Sanded, filled and ready to be covered. Now the fuselage.
F.
Da Fuse!
Cut the fuse out of 3/32 balsa. Yes, Guy, a port and starboard side....I triple-checked. :D
Added:
- 1/64 plywood doubler for the front half of the fuse. This paper thin plywood (cut with scissors!) and epoxy makes balsa bullet-proof.
- tri-stock at the lower front. Triangular stock allows the corners to be sanded round.
- 3/16 square balsa at the top for rigidity and to help glue the angled top half.
- cut out the formers from 3/16 balsa.
Note the second photo. Proof that a pattern-type plane has a length equal to span. Added at the front is the prop and spinner. The rudder hangs fully off the back.
Ready to put it together.
F.
Glueing the fuse together.
Here are the steps I use:
1) draw a datum line on the building board- used a pen on my drywall building board. Photo 99.
2) mark the centreline at the base of several formers. Photo 00
3) pin the formers to the building board on the centreline. Photo 01.
4) Glue the second side to the formers and pin it in place on the formers. Note: I did not pinch the back end yet. Pinned the first half in place where it ended up and matched the distance from the centreline on the second side. Note the rubber band on the front to pinch it together. Photo 04.
5) let the glue dry.
I learned never to glue fuselage sides together without pinning it down. It was a banana. It happens because of different densities of wood, amount of glue, bad luck,
Andy's hex, balsa revenge, etc. ;D
Frank
Quote from: Frank v B on May 07, 2023, 10:17:28 AM
Da Fuse!
Cut the fuse out of 3/32 balsa. Yes, Guy, a port and starboard side....I triple-checked. :D
Good to know, unfortunately, you will not have 2 planes...
Guy, two fuses need two wings or I still only have one airplane.
Pinched the back end together. Added the top outline and the turtle deck formers.
F.
How to make a vented firewall for an in-runner* motor.
step 1- take a random piece of plywood larger than the fuse cross section.
step 2- drill a hole in the middle for the shaft and measure the mounting hole centres. Drill all 3 holes out. Photo 43
step 3- mark the 4 vent holes on the perimeter of the motor housing- I used a pencil. Mount the motor to the firewall and mark the hole locations on the back of the firewall. Photo 44
step 4- connect the dots with a pencil to get an "X". Photo 44
step 5- measure the holes from the shaft and mark the X in that location.
step 6- find a drill bit the diameter of the event holes and drill through. I used a drill press. Photo 45
Finito!
Last photo (49) shows the motor and firewall glued to the fuse with 5 minute epoxy (what else!). Once dry, trim off the excess plywood. I use a razor saw and a sanding block. Takes 5 minutes.
Frank
* an in-runner is one that has a permanent magnet shaft and electro magnets on the outside housing. Most motors we use are out runners with a spinning bell containing the permanent magnets.
Covering
Covered the wing in yellow at the covering seminar at Mark's place.
Covered the fuselage in red to match the first photo. The photo on this post shows the first job was to cover the nose. The second job was to cover the corners of the hatch.
The second photo shows the alignment of the stab while the glue was drying. The toothpick is to help align it with the wing. I push the toothpick into the fuselage until the stab is aligned with the wing when looking down from the firewall.
Note- the covering has not been shrunk yet, otherwise it would peel back when the center portion is cut out so the glue will adhere to it.
Frank
Hinging
step 1- cut the corners of each hinge so it easily pushes into the slots. Photo 21
step 2- put a pin in the middle of each hinge so it is guaranteed half goes into the wing and half into the aileron. Photo 22
step 3- apply glue. Most people use thin CA. I cannot because my wife is allergic to CA*. I use hinge glue which is looks like a watery carpenters glue. CA glue is dripped on with the aileron in place. This glue needs to be applied to the hinge, then slipped into the slots. Photo 26
step 4- make sure you tape the aileron in place so it does not move when the glue is applied (CA) or has to dry (hinge glue). Photo 25
Frank
* no problem. The choice is either get rid of CA or get rid of model airplanes. Easy decision. "Yes dear" ;)
It must have been a rainy day in Toronto.
Great progress on your little rocket of plane.
Guy
Installing the fin/rudder....straight!
I use a triangle with the corner cut off so it automatically holds the fin at 90 degrees to the stabilizer while the glue dries.
Also installed the aileron servo. An HS 55.
Frank
ps: this photo was taken so Andy could mine the background. Yes, my work desk looks like the back of my car. :)
Done!
Looks like the plane in the first post.
Still have to connect the servos/pushrods/control horns and install the radio but the building is done.
Will post the weight when everything is done and the plane is ready for its maiden.
Frank
Nice looking plane!
Looks fast just sitting there.
Maidened it on Monday. It flew but made mostly noise and underwhelming speed-wise.
Also, ran out of trims so a little tough to fly.
Tried it again today. It was a whole new airplane.
Increased some throws (aileron and elevator), decreased the rudder throw, moved the battery back an inch (max. possible) and changed the prop from a 6x3 (GWS-like) to a 6X4 (APC).
Very quick and flyable but the ESC got hot. Will change the prop to a 5x5APC which is what I usually use with this motor (E-Flite inrunner- series 6- 34 amps).
Will probably be quicker* because it hits the motor's sweet spot.
Thanks to Simon Chapman for the hail-mary launch.
Frank
* increasing the pitch gives speed. Racing props are "square" which means pitch is equal to diameter. EF-Racing props are 8x8, Nooner racing props on high KV motors are 4.1x4.1.
Received these photos from Andy.
He always takes great shots...and photos as well ;D... but hardly ever posts them.
These are his photos.
Vadim did the launch.
Frank
Changed the prop from a 6x4 APC to a 5x5 APC.
Flew it yesterday. Wow!! what a difference.
The speed is now just below a Nooner. That is quick.
Very flyable. Neat project.
Frank
It flew great Frank - Congrats!