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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Das UglyStik

There is no better looking plane than something square, boxy and odd – Thus the Ugly Stik.

I could not locate any plans for one of these, so working from a picture I hot wired a wing with a 10″ cord, 29″ in length. The airfoil I chose was the ‘ultimate’ (low wing design) from airfoiltools website.

From there, a guesstimate of fuse length gave me a 24″ nose to tail length. Fuse built from some 10mm depron, and some 3/4″ pink insulation.

Rudder and Stab were cut so they looked right to my eye….

For a motor, I had a 2628 1250kv kicking around, so I used that along with an 8×5 prop.

C/G at 1/4 is achieved with a 3s2200 at the nose.

Stickers were cut using my Zing CNC.

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ScrPush1 Twin Boom Scratchbuild

So I have an urge to build a double boom plane, pusher style, using the hotwire wing method, and possibly the fuse in full foam design.

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I came across an interesting article about the “SO” series, a guy that does many scratch builds, and has perfected the two boom pusher plane. His website and rough plan outline can be found here:
http://www.foamflyer.info/plane.html

He is using the stepped wing design, basically foamboard stepped back to create a KMF2 style wing. As well, his design is a 30″ wingspan.

In my mind, I want a slow flyer, that is very stable in the air, so I am changing the design to what I think may work. The wing is cut from a standard clarkY airfoil design, flat bottomed to accept the rear booms or spares, and with some form of dihedral.

Since I do not want a standard dihedral wing that angles up from center, I built a wing (38″ total span rather than the suggested 30″) that has it tips angled up – I have no clue what this is called, nor if there are measurements I should be following…

I used some short pieces of foam, hot wired the airfoil shape, fired up the table saw, and tilted the blade a few degrees – darned if I know if it will even work!

One interesting article I also found was making spars using foam board, but in a Triangle Shape for strength – so that’s how the spars will be done, rather than wood or carbon.2016-02-20 14.42.18

Introducing the WTF

Since I had the foam cut wing, needed something to mount it on…

The wing has a cord of 230mm, with about 7degrees of dihedral. Since the cord is close to the tundra, I just used that plane to loosely create the rest of the dimensions. Length of fuse is just under the wing length, rudder and elevator has approximately the same surface area as a tundra.

To create the fuse, I used the technique as defined by experimentalairlines utube channel. Basically is a 3″ square tube created from depron covered in wingtape.

The motor is mounted on an aluminum bracket I created, with  the motor size the largest I had on hand, a 2826/1350kv. This comfortably swings a 10×7 master airscrew prop.

Testing with a 3s, it appears there is sufficient pull at 3/4 throttle to let the plane hang in the air. I don’t think the motor mount is sufficiently strong as I get vibrations introduced at an arm just above half… Oh well, to quote Hassan, “its just a Foamy!” haha.

Finding the CG is interesting. I came across an article that says to build the fuse, including electronics and battery, and lay it on top of the wing, at the highest point of the wing camber. Balance the fuse so it sits exactly at the highest point of the camber, mark both fuse and wing and transfer these marks to the top. Doing this, the plane now balances at a cg between 1/4 and 1/3 – exactly where I would expect it to be.

As for wing loading, angle of attack, thrust etc in the way of calculations, there have been Squat Done! Lets just see what happens!

If this thing actually survives a maiden, I have two things to do to it. First is to add landing gear, and the second will be to add reinforcement in the wing. As of now the wing is only foam, without even any tape for strength.

 

 

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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

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Another Mig29 Red

This is the plan from rcpowers, but with changes from the previous build.
KMF4 Wing design used – top & bottom step plate.
Since wing is so thick, did not use any wing reinforcement spar.
Rudders added – used 5gram servos as I miss not having a rudder.
Did not reinforce nose…. since additional servo weight could be offset by battery placement.

Receiver is the new Orange RX with Telemetry. Tapped into battery lead before battery plug and added JST connector. Temperature sensor just left in fuse near battery since ESC mounted external.
Very Cool – Telemetry works perfectly with DX7.
(note: when first binding RX, do Not use the throttle position on the RX, use the any other like the rudder or elevator. There were reports that telemetry can be disabled if binding occurs when the throttle channel is active at bind) The DX7 immediately recognized the telemetry once RX was bound, but you have to add the temp at Volts to your DX screen to see and hear the telemetry.

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Nova Jet

Rendition of the rcfoamfighters Nova Jet.
2800kv Super megajet motor from Greyson with 40a esc and 3s2200 battery.
Left out thrust plate, shortened fins, changed canopy, shortened nose.
Not a lot of time put into this, as no clue if it will fly!
Maiden will tell all!

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Made from silver backed 1″ foam (8×4 sheet from HD)

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Silver backing left on for strength

 

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Green coating on opposite side, left on and covered with wing tape