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Feb 21, 2018, 11:31 AM

Building the plane EzAgle

Hi!!!! After so many attempts to build the easiest plane I could using the cheapest material I can find (I didnt use depron/foam or things like that, they are veeery expensive here in Brazil, a single sheet of foam with 5mm thick is at least USD $ 12) I finally succeeded! I am so in love with this plane that I already built at least 8 of them and currently I have 3 of them assembled in my ceiling!

I had too many people helping me on the way, special thanks to @balsa or carbon and @extremeSports which were very kind and patient. There are really great and easy planes to build in this RCGROUPS community. The EzFly, SE and Beagle are great planes to start from and those were the planes that hooked me into this hobby. However after building those 3 types of planes many and many times I found some shortcuts that worked great to me.

Those shortcuts make the plane easier to build (not saying the other 3 planes are hard, they are not!), cheaper (way less styrofoam is used) and with less work measuring/cuting styrofoam. At the end, because of the lightweight and because of the "different" tail design, it can easily tow a banner of 1.3 meters (90 cm) even using a 11 inch prop in a 3S not powerfull motor! Yeap.

AND I THINK THE MOST IMPORTANT REASON for building this plane: if you make some mistake with the misalign of the wing and tail, or rudder... you will still get away! Beginners make lots of mistakes, at the end things dont look aligned and it makes a bad flying experience. SO PLEASE read the tail section (a few paragraphs below) and you will see why this tail is great!

So first, here is the end result below. If you want to see the plane flying towing a banner watch this short clip ->

Let's start the build proccess by the wing. I used the lid of a salmon fish styrofoam box. You can see it below:

I used this lid cause it has a veeery strong styrofoam, it's free (you just need to go to some sushi restaurant and take a look at their trash and grab the lid). You wont need to buy foam and the resulted wing will be as good as one made with foam! After taking that lid cut it like the image below:

Here is a video of me showing the lid and the cutted lid. It's in portuguese but I dont say anything important.

After that you need to do some sanding, lots of it. You need to sand the lid so it gets closer to a good NACA airfoil so you can have good relation between drag/lift. To help me with that I 3d printed the negative part of the airfoil to act as a template so while I am sanding I can check if I need to sand more or not. Here is the negative part of the airfoil used as a template:

I placed a ruler close to it (which measures in inches and cm so you both worlds are happy). You can download the 3d printed template attached to this thread. Ok, go sanding the styrofoam till it gets close to the picture below:

After that you will have a very nice wing! Now you just need to add some normal styrofoam cutted part to each end of the wing. This will act as a dihedral and will help you satiblize the plane, it makes it a muuuch more smoother experience adding these 2 styrofoam cutted parts. See the template below:

I cutted the part above using a 10mm cheap styrofoam which you can buy in any stationary store. After cutting 2 identical pieces, GLUE THEN to each end of the wing in a 20 degree angle (aproximatelly, it does not need to be perfect, I think if you get from 10 to 50 degree it will still be very good). The end result will be the image below:

You can see I glued some barbecue stick to the middle of the wign to reinforce it BUT I THINK you wouldnt need that, the wing will be very strong without that. You dont need to reinforce it. You can also see I cutted some notches at the top and at the bottom of the middle of the wing so it will fit nice in the body of the plane. Dont do those notches now, go to the next steps and only do that at the end with the dimensions you need.

Now the body! The body of the plane is very simple. I attached 2 PDF files, one using an A3 paper and another using A4 paper (2 pages). You just need to print that and you will have your body template. See the body template below:

It's very simple. To cut that I advise you to grab another salmon lid box and cut that template using the same material. It will have a very strong body and you will be able to crash it a lot before you seriourly damage it. See the end result below:

I already added the electronics, motor and everything else. The 3D printed parts can be found attached to this thread. They are very easy to print, I designed them my own and you will have no problem printing them and work greak.

Now lets go to the tail. The wood stick between the body and the tail is 30cm in length. You just get any wood stick (or carbon fiber stick if you can afford it) and glue to the body and tail.

This tail, to me, is special. It allowed me to build a not well aligned/measured plane and it still flies veeery well. First lets take a look to the tail below.

You will see the 2 control surfaces are the only surfaces at the tail. Usually a plane has "4 surfaces" at the tail (V tails too), see below:

I decided to only make the tail to have the orange surfaces in the image above. It creates less drag AND if you misalign the tail with the body of the plane, with the motor or even with the main wing YOU CAN STILL get a good flight! JUST trim it right. Yes, you just need to trim it and it will fly great. You may be wondering "well, I can also trim a plane with 4 surfaces as show above". I would say YES you can, BUT when you trim you are only changing the 2 control surfaces position/angle, you are not changing the other 2 control surfaces (total of 4). This will generate a lot of drag if you trim a lot your 2 control surfaces cause you will still have 2 other control surfaces not well aligned.

SO if you have only 2 surfaces at the tail AND if you can trim them, you will be fine! Even if you have to trim it a lot (in one of my planes the rudder had to be trimmed 30 degrees to the left beucase of a stupid mistake during the build process) you will still be fine, you will not have lots of drag being generated just because you built the plane not aligned.

The tail is very easy to build. I used a straw with a thin barbecue stick in the middle to allow the control surface to change angle and everything went fine.

The tail dimensions are below:

So far I've been building many of these planes and they are "fool resistant", "beginner resistant" and "crash resistant". You dont need to measure things seriously, you will get away with this plane if you try to follow the dimensions but still get a misaligned plane at the end.

Before your first flight REMEMBER TO keep the CG at 20-30% from the leading edge of the wing. If you do that, despite some mistakes you may do, it will fly nice! The CG is the only thing you really need to worry and try to get it as close to 20-30% range. If you are out of this range you will have a poor flight experience.
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Feb 22, 2018, 04:16 AM
Registered User
JabiruAbe's Avatar
Love it! great use of recycled foam. So the fuse holds up to crashes pretty well?

I would think if you ran the tail boom all the way along the bottom of the fuse it would be stronger still.

Feb 22, 2018, 02:22 PM
@JabiruAbe You wouldnt believe if I tell you here in my city most restaurants send all those strong styrofoam to the trash, they dont even recycle!

I already crashed this plane a lot, mainly in the landing cause sometimes I fly in places with no landing space so usually I hit the ground hard, with nose, hit branches of trees... and the plane holds pretty well! This salmon/tuna styrofoam box is pretty strong, good material.

Your idea of using the boom all the way is great! It wouldnt add too much weight and would help on hard landings! But so far I had no problems with the body of my plane breaking, sometimes the wing desataches from the body (cause I made the wing attachable so I can take this plane inside a bus) but it's an easy fix.
Feb 22, 2018, 05:28 PM
Registered User
JabiruAbe's Avatar
Yeah okay it must be stronger foam than we have here in AUs!
How do you find the battery goes being at the front like that? does it get damaged in a crash?
Feb 25, 2018, 04:06 PM
@JabiruAbe You mentioned something reaalyy important that I forgot to say in my thread! The other great advantage of this design is that if you crash the battery will 90% of the time get loose from the plane and carry a lot of the interial momentum with it, avoiding damaging the plane! If you crash and your plane, during the crash, is attached to the battery the plane will have to slow down the battery and probably the plane will get damaged.

If your battery gets loose and moves away from the plane during the crash it gets much more gentle to the plane.

Of course, batteries are not built to be flying away, but I still didnt get any damage to my battery and I think one of the reasons this plane lasts so many crashes is that the battery (which is 1/3 of the weight of the plane) detaches itself in a hard landing/crash!
Feb 25, 2018, 09:11 PM
Registered User
JabiruAbe's Avatar
Ah yep makes sense. A clever escape mechanism!

Have you tried hotwiring your wings? it would be much faster. I built mine last night, it took about an hour. Just PVC with a guitar string. I power it with a 2S lipo, but you can use any 12V 2A power source.
Apr 19, 2018, 02:58 PM
@JabiruAbe hotwiring it a great idea. I didnt have the big size hotwire "equipement" to do that. So I built one (alsmot exacty as you said) and now I am hotwiring my wings
Apr 19, 2018, 03:52 PM
Scratch building addict
rotagen's Avatar
Good job, and real nice looking airfoil. I do the same thing a b-string ele guitar wire on pvc bow but I use 3S lipo.

Great idea making that fuselage shape - nice and light.

Even our plain old styro in the U.S. is plenty strong enough if you keep the plane light, which is easy to do with styro.

Another name might be Cooler Box Special.
Last edited by rotagen; Apr 19, 2018 at 04:00 PM.
May 16, 2018, 03:38 AM
Registered User
davereap's Avatar
You can make the polystyrene wings tough by giving them a covering of laminating film.. I use cheap A3 size pouches...

Also if you cant do hot wire cutting, a chamfered/angle cut profile works as well , I have cut some from the cheap builders foam..
Again cover with film if possible.. where film is not available layered paper, glued on works.. even news paper

chamfered wings...

The chamfered air-foil profile is basically what flitetest uses the most , although theirs is built up with a folded top foam layer..
Last edited by davereap; May 16, 2018 at 03:43 AM.

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