Elder 40 Scratch build

[GuyOReilly]

Thank you @Michael for lending me the Elder 40 plans.
I will protect them with plastic wrap and hopefully nothing will get glued to the plans.

I looked at your kit build https://temac.ca/smf/index.php?topic=3785.0

Very interesting and informative.

I have few questions and I am pondering a way forward on this « winter build » aka « retirement build ».

1- Power to use.  I have an E-Flight 25 available.  Would that be marginal power?
2- Wing ribs.  The kit uses 3/32.  I plan using 1/16. Would that be adequate?
3- Fuselage uses spruce longerons.  I have poplar that I can strip to 1/4 square.  Any concern other than weight difference?
4- The kit indicates using thin plywood veneer to secure the joints on the exposed portion of the fuselage.  This allows more gluing surface between sides fuselage cross pieces.  I was thinking lacing with « dental floss » or thin thread to assist with rigidity. Any concern?
5- For balance, I was wondering cutting a hole in the firewall so that the battery could be placed far forward to assist with balance.  Any concern there with solidity and integrity of the firewall?
6- Landing gear.  I will use the wire wheels (see other building thread) and will place it further back than the kit. Here is a link to the build : https://temac.ca/smf/index.php?topic=8714.msg57913#msg57913
7- Tail section will be re-shaped as I like the look of round fin/rudder, similar to DR1 and the stab will have an increased area by rounding the leading edge.

I will post pictures soon of the work completed so far.

Thank you for your ideas.
Guy

[GuyOReilly]

Work completed so far:
99- Made a round Fin/Rudder
99- Made a rounder stab and elevator.
01- Tail skid
02- Pilot
03- Gun and wire post.

[Michael]

1- Power to use.  I have an E-Flight 25 available.  Would that be marginal power?
2- Wing ribs.  The kit uses 3/32.  I plan using 1/16. Would that be adequate?
3- Fuselage uses spruce longerons.  I have poplar that I can strip to 1/4 square.  Any concern other than weight difference?
4- The kit indicates using thin plywood veneer to secure the joints on the exposed portion of the fuselage.  This allows more gluing surface between sides fuselage cross pieces.  I was thinking lacing with « dental floss » or thin thread to assist with rigidity. Any concern?
5- For balance, I was wondering cutting a hole in the firewall so that the battery could be placed far forward to assist with balance.  Any concern there with solidity and integrity of the firewall?
6- Landing gear.  I will use the wire wheels (see other building thread) and will place it further back than the kit. Here is a link to the build : https://temac.ca/smf/index.php?topic=8714.msg57913#msg57913
7- Tail section will be re-shaped as I like the look of round fin/rudder, similar to DR1 and the stab will have an increased area by rounding the leading edge.

1. An E-Flite 25 (on 4 cells with 60 amp ESC) will probably be enough for the plane to fly, but aerobatics may be difficult. You will need more weight at the nose to make up for the lighter motor.
2. 1/16" ribs should be okay.
3. I don't know which wood is lighter or stronger, but more weight at the rear (anywhere behind the wing) will make it more difficult to balance. It must balance as per the plans.
4. The small plywood plates work well to keep everything glued together. I wouldn't omit them.
5. I think that's okay.
6. Moving the wheels back may make takeoffs and landings more difficult.
7. Rob also used a rounded fin/rudder. Ir works fine.

Nice and fast work so far!

[GuyOReilly]

Thank you @Michael for confirming some of my thoughts.
Building light will be key.
I researched the performance of the E-Flight 25 and found the following.
Key Features
    Equivalent to a 25-size glow engine for sport and scale airplanes weighing 3–5.5 lb (1.4–2.5 kg)
    Ideal for 15-size 3D airplanes up to 3.5 pounds (1.6 kilograms)
    Ideal for models requiring up to 600 watts of power

I will need to source the 1/16 ply for the fuselage construction.
The nose weight should be taken care of by the placement of the battery extending through the firewall.
Additionally, the wing structure will be redesigned and based on the Carl Goldberg Eagle 2, using a dowel for the rounded leading edge and no capstrips.
The covering (and so many other things) remains to be decided, but I was inclined to go with dope and fabric covering.  My concern is the potential for warping the wing when covering.

[GuyOReilly]

Cutting ribs using the stack method proved less than successful. 
A template was produced (3D printed by John Dutkowski) and in less than 5 minutes, 5 perfect ribs!!   
The project continues, 25 or so more ribs to go.... 
I will need some more 3/32 balsa sheets...

[msatin]

I understand you have the template, but when cutting the ribs are you doing them one at a time "manually", or are using a bandsaw (or some other type of machine)?

[GuyOReilly]

I understand you have the template, but when cutting the ribs are you doing them one at a time "manually", or are using a bandsaw (or some other type of machine)?

Good Morning Mark;
One by one, tracing with a trusty and new #11 blade.
I think that the scroll saw would vibrate too much and rip the balsa up.
The template needs to be held in place; I used 2 nails in small holes because a small clamp would not allow cutting all around.
Once all cut, a punch will be made from aluminium tubing (1/2 inch or so) to make room for servo wires.
The notches for spars will be added top and bottom with a small saw by stacking the ribs.
More to come.
Guy 

[octagon]

I did the same building my Elder Guy. A nice little trick is to glue a piece of sandpaper to the bottom of the rib you are using as the pattern. Stops it from slipping on the balsa shee.

[GuyOReilly]

I did the same building my Elder Guy. A nice little trick is to glue a piece of sandpaper to the bottom of the rib you are using as the pattern. Stops it from slipping on the balsa sheet.

Great idea!! And it works.
Just done 6 more ribs in 4 minutes!
Progress.... but back to work now...

[GuyOReilly]

Rib and half-rib blanks all cut, remains the holes for servo leads, L/E cut-out and slots for the top and bottom spars.

[GuyOReilly]

Wing construction advances.
Made myself a jig to punch holes for the L/E dowel and for alignment.
Trial fit and a bit of sanding with Duragrit.
Quite pleased with the result.
Next cutting for the spars.

[GuyOReilly]

Plan laid down and protected (Thank you @Michael )
Some trial fitting and trying to figure out the spars and trailing edge etc.
Also, I will have capstrips approximately 1/8 by 1/16 on all ribs and half-ribs.
Center section will be covered with 1/16 and fiberglass/epoxy for strength.
Need to source some 1/4 square spruce spars.

QUESTION: Should the capstrips be placed only after the wing is off the building board?

Guy

[msatin]

Great progress Guy!

[Frank v B]

Guy,

Just so the TEMAC building world will not think I ignored your request for help.... I called you with some clarifying questions and gave you my opinion.
This is important so that if it works, it is your victory. 
If it doesn't work it allows you to say again  "It is Frank's fault". 

Happy building... and keep building.

Frank

[GuyOReilly]

Back into the build.
Tackling the fuselage and trying to understand why the fuselage sides do not go to the firewall.   
The fuse sides stop at F2, then the bottom and top doublers as well as the landing gear support doubler are added and they go to F1.
This is a confusing plan and building sequence.
I am planning on changing the fuselage side to go all the way to F1, retaining the doublers as they add rigidity.
Another change I will be making is the design of the "U-SHAPED" formers and the use of tabs.
I will not be cutting tabs and slots in the fuselage sides; butt glued will be ample strong.