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Jun 17, 2019, 06:35 AM
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Build Log

Aereon E-RES Scratchbuilt Project

Hello all,

thought I'd start a build log on my latest project, a 2m E-RES plane. It was supposed to be finished by now but due to lots of other distractions I just got started now. Droll thing life is.

E-RES is the electric version of RES (Rudder Elevator Spoiler) which is increasingly popular in some parts of Europe. There are however not many competitions around my place and I doubt I will ever compete with it, but never the less I try to stick to the regulations with respect to functions and building requirements. It would certainly make for a valid entry to any altitude limited event albeit with 2m wingspan it will be in another league as opposed to full blown 4m F5J ships.

As I understand it the E-RES regulations consist of RES models, plus electric motor which switches off at 90m of altitude or after 30sec or at pilots discretion, whichever occurs first. Working time is 390sec from launch, concluded by spot landing. The most comprehensive on the rules I found here: Link

Model is supposed to be built up from wood and cover, with composites limited to wing spars and leading edges and tailbooms. Max span 2m.

Next up: Model design specifics.
Stay tuned;-)

Andy L
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Jun 17, 2019, 07:02 AM
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After many drawing revisions, drafts, attempts and trials, the following are the resulting model specifics.
As I spend all of my working day staring into computer screens, I minimize computer support to the design process and draw all parts by hand, except the ribs that is.

Model Type: E-RES 2m Electric Powered Sailplane
Wing built from balsa ribs, I-beam spar with carbon fiber caps and balsa web, carbon leading edge, fully open with oracover finish
Fuselage built completely as balsa box, plywood formers
V-tail built up as a balsa truss structure

Span: 2000mm
Length: 1250mm
All up weight: goal of 550g

Propulsion: Hacker A10-7L 4.4:1
Propeller: RFM 13x9
ESC: Castle Talon 15A with BEC
Battery: 3s 850mAh
RX: Graupner Hott
Servos: KST X08

Wing details:
Wingspan 2m, Area 0.3664m2
3-panel wing with constant chord non-dihedral center panel 800mm span, two outer panels of 600mm span at 12deg dihedral each
Airfoil: AG35 constant for center panel, transitioning to AG38 at the tip
Center spoiler

Tail details:
V-Tail, projected stabilizer area 0.04m2, opening half-angle 50deg, 5mm flat plate section, fully field-detachable

Now off to the workshop ;-)

Blue skies, Andy
Last edited by Dotcom; Jun 17, 2019 at 12:21 PM. Reason: Typos
Jun 18, 2019, 05:42 AM
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Started with the formers. Drilled and cut by hand, never at the accuracy of CNC but still good enough;-)

I made a copy of the formers drawing, glued it to 2mm plywood, and drilled and cut them. The paper is easily removed afterwards.

Jun 18, 2019, 04:08 PM
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Building the fuselage.
Standard wood size is 10x100cm therefore the sidewalls and corner stringers need to be lengthened. The top line of the fuselage is straight so it can be assembled inverted on the board. The contour is drawn onto the sidewall piece and the stringers added, then all is glued to the roof. Don't forget to glue in the teflon tubes for the tail control.

So far all of this has taken ca 3hrs.

Jun 25, 2019, 03:56 PM
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Small update, the fuselage is mostly assembled, minus the parts for tail, wing and servo attachment. These will be glued in later during the alignment of everything. Next up will be shaping and sanding the fuselage, but for this it is just too hot outside. Before trimming all parts together weigh in at 90gr.

Jun 25, 2019, 08:35 PM
a.k.a. Bob Parks
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Originally Posted by Dotcom
.................... but for this it is just too hot outside. ....................

When I saw this I was skeptical, until I checked your weather, 92 F ! We think of Switzerland as mountains and snow!
You are at about the same altitude as Phoenix, AZ and we are predicted to hit 110 F this week, again.

Jun 26, 2019, 08:39 AM
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It is not typical for us here to have this high temps in June, but in the flatlands between the mountains where most cities are, we also get quite hot summers, maxing usually in August. On the other hand two days ago I went out with my DLG and caught some crazy thermals. But jumping around in the heat was a real effort.

Meanwhile, some progress on the tail unit. It is a V-tail with 100deg opening angle. It should be fully dismountable. I chose 2mm steel pins sliding into carbon tubes for the joints. The tails are built directly on the plan. The full unit before covering weights 22g.

Blue skies,
Jun 27, 2019, 03:06 AM
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Tail attachment. It is supposed to be a low weight low drag but sturdy and easily dismountable design. After much consideration and planning and redoing, this is what I came up with. The seat on the fuselage will be glued once the plane will be aligned after the wing is on the fuse. Two 3mm nylon bolts hold the tail from the bottom. After all parts are ready I am quite happy how it turned out.

Now a short break for a few days, then it will go on with detailed drawings and construction of the wing.

Blue skies, Andy
Dec 01, 2019, 04:09 PM
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Some progress on this bird.

Got held up by another project, a small 3d Yak-54. That one is ready to receive the electronics, making room on the building table again.

Obviously, the wing is still missing. It is considerably more complex than the fuse and tails, and frankly I underestimated the effort sort of. As of now all the center panel parts are cut and ready for assembly. Spar is I-beam with carbon strips 8x0.8mm serving as caps, and 5mm balsa web. Ribs are 3mm balsa, airfoil AG35. Center panel also houses the spoiler and servo.

Nuff talking, let's see some images.

Jan 20, 2020, 03:22 PM
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Sometimes putting together the already existing parts helps to get into the mood to finish the last steps.

With the wing center section almost finished, it starts to look like an airplane.

Missing the outer wing panels. First I need to make a tool to layup the square wing joiners at 12degrees so that the joiner tubes can be aligned in the spars of the outer panels. While the resin cures I can already start making the ribs.

Blue skies,
Mar 10, 2020, 03:36 PM
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Some progress.

Before the tip panels can be made, the V-joiners are needed so that the tip panels have the joiner tube installed at the correct alignment.

Dihedral of both tip panels is 12deg. I use a square 8x8/7x7 pultruded carbon tube as joiner tube. This allows the easy making of a mold in which to laminate the joiner itself. See pictures for details, hope my explanations make sense:

Take two pieces of joiner tube, remove one side of the square and glue the resulting C-section with the opening towards the top to the bottom board at the desired angle. Trim top flush and install four screws for support of the top board. Stick in tape to reduce joiner crossection, wax , and laminate joiner with tow. Place top board and slightly clamp. The resulting joiner easily removes from the mold and can be used after minimal trimming.

Now it is off to make the tip panels, and then a major sanding session!

Blue skies,
Apr 21, 2020, 03:26 PM
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Continued for the wingtips, simple balsa assemblies.

Still missing after this session are a couple of small things: Some corner reinforcements, wing joint wedges, wrapping the spar with carbon in the joiner area.

Getting there...
Jun 07, 2020, 03:14 AM
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On it goes.

Before covering, some small details are still needed.

The wing joints need a wedge shape piece on each panel to fill the 12degree dihedral gap.

Also, the wing joints got pins to hold the torsion.

Finally, the spoiler was prepared.

Blue skies,

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