Tag Archives: foam

Scratch Builds

Have not been posting here in a while, weather is changing and not as many opportunities to fly, so don’t do as much building when I cant maiden (crash) the creations.

Here are a few over the last few weeks:

My rendition of the Balsa Plan called the wot4 or watt4. Scaled the drawing down to 45%. High wing but fully symmetrical so wanted to see what it can do. No rudder servo, 1540kv motor, 7×5 prop.




FrankenPlane: Wings are from a smashed Katana, elevator from a smashed Bravado, fuse and tail hot cut foam. Powered by a 36series 1500kv motor, should be interesting to see if it will fly!




Profile plane, modelled after the electrifly 300 – this flew very well!


Combat Wing Build Log

Have been having so much fun with the gremlins & wings, as fun to fly no stress scratchbuilds, that its time to build wings for Combat.

First they have to be Cheap to make, and take little time to build since the expectation is they will be crashed in short order!

I started looking at A. Newtons site, where he hot cuts wings based on the FT mini wing plan. Well, the LAR principle kicked in as I started copying his template, and it just did not:
Look About Right!

I wanted a wing with the CG easier to meet, based on some ZRM motors I have from an old quad, a 3s 1300 pack and enough reinforcement to keep these wings together for a while….

My template,  when the LAR principle kicked in, has a wing span of 735mm, Root chord of 315, Tip chord of 163 and a sweep of 234mm. All this translates to a calculated CG of 145mm.

More to come as I add motors, corroplast fins, etc!

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Finished – coroplast winglets, 2300kv swinging 6×4 prop with blheli matched esc’s.

2016-06-22 20.18.02 2016-06-22 20.17.28 2016-06-22 20.17.16

LAR #1

Welcome to my new series, no more WTF XX, it will now be the:    LAR XXX Series!

Looks About Right #1

Noticed the scratch built sBach full fuse, so decided to make a version.

Had a hot cut wing laying around from when I was trying out cutting a tapered wing, so that became the base unit, with all other dimensions based on this wing.

This thing balances nicely with only a 3s 1300, and the motor is an old 28 series 1200kv I had on a tricopter – prop is very small for me, 8×4.5, but seems to hold the LAR #1 in the air at only half throttle, so should be interesting to fly.

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Slo Stik (sort of…)

After building the das ugly stik in the previous post, I got to thinking that I have a ton of 4S 3000 to 6000 batteries kicking around from the multi-rotor days, that are just going bad.

The question was, could I build something to use them, or if they were too heavy, could I utilize the same plane for the standard 3s2200 that we all have so many of.

Looking at pics of the slo stick, it looked like something I could adapt to any battery configuration, and even potentially use the platform for testing wing designs.

Wanting to start using up the ton of laminate film I have, I started with a full length of depron foam, and covered it in 3mil laminate film. This gave me a 39″ wingspan. Figuring I need plenty of lift, I took this, and using the Armin Wing technique, created a wing with a 13″ cord (inc alirons).

Now that I have a wing, what to mount it to…  Had a few pieces of 10mil square carbon tube from HK – bingo! Not sure this stuff is really carbon, seems to cut rather easily, but what the heck, its a Fuze!

Now I needed a motor large enough to move this thing. Found an extra SunnySky 3508v from one of my bigger multi-rotors, that swung 13″ props. This should work(?) — Stuck an 11″ on this motor at 700kv with 4s – seems to pull fairly well but may have to move up to a full 13″ prop.

The entire key to this build was its ability to accept any battery or any wing I wanted. To accomplish this, The entire Wing and the entire Landing gear/battery tray are completely Moveable anywhere on the frame length. This gives me the ability to set CG with any weight of battery at all, be it 3 or 4 S.

These fully moveable sections should allow me to use this base frame for just about any wing or battery combination I want to try…..

At least, that’s my Theory! hahahaha

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Hotwire for Foam Cutting

Decided I wanted to cut wings out of foam, here is the build specs:

Wire – 26g NiChrome Wire at a length of 850mm between the alligator clips.

To heat to +600 degrees for foam cutting, at the 850mm length, I found that +3 amps was needed. Located a laptop power supply that output 12volts@3.4amps. This works perfectly on this length of wire.

A switch is necessary as the wire heats up and cools down quickly, so grabbed an old standard wall switch and cut positive pole after the transformers output. With no draw the transformer goes into shutdown mode so this is safe.

For the frame, its simply poplar, hinged with a single 1/4″ bolt and fender washer on each leg. To provide tension on the wire, a tie down strap is used, and to increase tension as the wire lengths from use, I just tie a know in it to increase the opposing pull.

The internet says the most stable airfoil design is the ClarkY, so I created a few wooden templates of varying chords. A standard 250 chord with a 100mm thickness was plotted using the tool found at ‘airfoiltools.com’. To make things easy, I simply opened the .svg inside Inkscape, copied and pasted into Word. Here I expanded the size for various templates.

Foam – this is tricky. The white foam from the DIY stores is not the best choice, nor is the foam ‘craft pak’ they sell. What I believe is makes this so bad to try and cut is that this white stuff is Expanded Poly, and it is not dense enough to give a good cut, nor provide and rigidity and all. What needs to be used it Extruded Poly. I found this in a blue color, at 2″ thickness, and it cuts great and is extremely rigid. Obviously weight is now a factor, but until I try to fly one of these wings, I cant say for certain if its too heavy.

I found that the best cut length is 2′ at a time, this provides the most clean cut as you are not pulling a wire thru too much foam at once. The pics below show a 7 degree cut face being gorilla glued to a flat face to provide a wing with a slight dihedral, and a few of the airfoils I have cut so far

2016-02-11 16.19.55

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