Aviation Design's Diamond 70mm EDF - Plans and Build

DamoRC

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Pod build is now added to page 1.

Looking pointy!

11 Complete.JPG

IMG_2479.JPG
 

DamoRC

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Michael - thanks for the interest - yes I will try to put together a full size version of the plans . I just need to figure out how to make it work in the software. Probably just as well that you aren't using the tiled version as I had to remove it because I discovered significant air restriction problems to the EDF.

In an earlier post I had indicated that I was getting approx 38 oz static thrust from the EDF installed in the fuse and that this was better than what I had seen in an earlier prototype. This test was performed before the wing, canopy, and decking were installed. I joked at the time that either the new thrust tube was doing its job or that without the additional parts installed, there was no restriction in the air flow getting to the EDF. Turns out it was the latter. A static thrust test on the completed plane yielded just 26 oz of thrust, a 12 oz (30%) decrease. I opened up one of the canopy sections at the top of the plane and the static thrust increased to 34 oz and when I opened up a section section it increased to 36 oz. I have pushed the opening for the EDF intake back 1 - 2 inches and gained a couple of oz back. I don't really want to cut holes in the base because this is a belly lander and it will just suck stuff into the EDF. So I need to figure out a way of creating an opening in the canopy or decking that will allow better air flow. A bit disappointing, but I hope to have it figured out soon.

DamoRC
 

DamoRC

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That thing is really cool looking. I hope it flies good for you. Cant wait to see some video.

Thanks!

This is a video of an earlier, larger prototype


And this is a video of an earlier build at the current size.

 

FoamyDM

Building Fool-Flying Noob
Moderator
Great job on the build thoroughness and details. Just reading this, I learned a great number of building techniques! (the iron, and center tape hinge)

This looks just spectacular.

How did you model/mock this up so the cockpit and nose come together so nice?
 

DamoRC

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Thanks FoamyDM!

To be fair, I cannot take any credit for the use of the iron or the center hinge. I think folks have been using these techniques for some time - I just leveraged them to suit the application.

I used sketchup for the modelling. It's pretty good for this stuff. One piece of advice I would give is to avoid getting into a vicious circle of trying to make minor improvements, leading to tweaks in one part that then need to be aligned with a tweak in another part - this can go on forever (at least it did for me). The other piece is to think about the foam, it's thickness and characteristics, and how that might influence the real world model. It took me a while to get used to thinking about the model in those terms and I spent way to much time tweaking the model in sketchup, adding little value, instead of trying to get it to foam quickly.

ADD Full.jpg

This is another model I am working on. which is coming together a lot faster because I am testing it out in foam earlier and not tweaking the living daylights out of it in sketchup.

GP5 Proto.jpg

IMG_2493.JPG
 

DamoRC

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Thanks Frankschtaldt!

Unfortunately, to fix this air restriction problem, I am going to have to butcher it a little.

It won't look quite as good - but it will still be pointy!:)
 

FoamyDM

Building Fool-Flying Noob
Moderator
I know you didn't invent the Iron method or the Tape Hinge :rolleyes:, but you are the first I've seen to take pictures of it during the build with enough detail to understand how specifically it gets done successfully. I was guessing at how these methods might work (base on the names) It's not just the process pic, but the next couple pics are of how it affects the finished product (like a - before the method *sparkle magic* application *sparkle magic* Look at the like-new finish). As a New and avid builder and having attempted a couple stabs at a new design or two. I routinely Forget to take pictures while building and I just have Cut stuff - Cluster of half-finish parts - The taped, finish product. I always fail to capture the in-between details a new builder can use to expand their building toolbox. So kudos to you with this build thread :applause:

I vote you should turn this into a build article. Anyone second?

Also great Sketchup Model!

I have pushed around with sketchup but typically with woodworking and thereby everything is angular square in general. Easy to model as the workflows to build a cabinet is almost the same in in real life as Sketchup. Easy translation. But Planes and 2d to 3d to skinning... a bit trickier for me.
Can you help this noob and explain the tools you rely on in Sketchup and or a brief list of steps past bringing in the pdf/jpg and tracing the shapes, like how to shape the skin and flatten it? (build formers & ribs, then use *this tool* to skin after selecting former edges, etc..)

the tutorials I've see fall apart for me when I think, "but I want to go beyond boxy and square". Your design moved past it.

Did I see your model in some indoor flight thing this morning, in the background of this video? about the 40s and 1:38 mark show it well enough.

P.S. - to make my wing flaps longer (64mm EDF sized plane) I glued poster board over the 1/2 foam to lengthen it and give it a taper. looks great. the iron does the taper without adding weight. :) anyway - Thanks for the great detailed info.
 

DamoRC

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Thanks for the kind words FoamyDM. I am glad that the build log was helpful.

I'll follow up on the sketchup piece. I like to build fast and therefore not a huge fan of formers or ribs. Although these elements are almost certainly the best way to design and build for accuracy and durability, I tend to have "disposability" in my mind when designing and building, that is, I expect to trash the plane in a finite (and typically short) period of time, so the faster I can build another one, the better. The image in my earlier post of the racer is an attempt to be an all folded fuselage - no formers, just folded foam).

Thanks again!

DamoRC

p.s. I think this is the plane in you spotted in the video you shared - crazy!

 
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DamoRC

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@ FoamyDM

Can you help this noob and explain the tools you rely on in Sketchup and or a brief list of steps past bringing in the pdf/jpg and tracing the shapes, like how to shape the skin and flatten it? (build formers & ribs, then use *this tool* to skin after selecting former edges, etc..)

I'll try, using an example (and too many pictures). This is how I would create the skin for a small piece of fuselage (highlighted in he pic below).

This is a model I am working on - I have the plan and side view drawn based on an imported three view.
1 First View.jpg

Note that the plan and side view panels are grouped so that anything new I draw won't permanently attach to these pieces
2 - plans are grouped.jpg

This is a zoomed in view of the section I am going to skin - note I have horizontal and vertical lines at the front and back of the section - I am going to use these to size the circle shape which forms the frame for the skin.
2A - reference marks for circle.jpg

Now start the first circle (at the front of the section). You may need to adjust your view angle so that its pointing down the length of the fuse so that the circle will draw vertically ("red" circle). You are starting your circle at the center of the fuse
3 - first circle start.jpg

Drag the mouse vertically until the circle locks onto the top of the vertical reference line and release the mouse. You now have a circle that is the right height
4 - first circle finished.jpg

Select the circle and then select the scale tool. We are going to use the scale handle highlighted in the picture to reduce the width of the circle to that of the fuse.
5 - scale tool and handle.jpg

Put your mouse over the handle and also press and hold down the control key. This sets the scaling to operate in such a way that the center of the object does not move, just the sides. If you don't hold down the control key, the circle will get narrower but also move out of position.
6 - scale using ctrl for center.jpg

Click on the handle and move it horizontally until it locks onto the end of the horizontal reference line. Click again to finish the operation. Now you can release the ctrl key. You now have a properly scaled circle.
7 first circle scaled.jpg

Repeat the process at the rear of the section to be skinned.
Hide the fuse panels so that all you see are the circles. In reality, the only part of the circles we are interested in are those highlighted in the picture (the bottom skin may have a different shape and so I tend to do these separately).
8 two circle quadrants.jpg

Select the unwanted quadrants and delete them so all you have are two arcs.
9 double click and delete.jpg

10 - two arcs left.jpg

The circle tool default is to create a circle that is actually made up of 24 straight line segments. So in our quarter circles we have 7 points drawing 6 segments. You can click on the arcs to see where these straight line segments are. To create the frame for the skin, use the line drawing tool to connect the points between the front arc and the rear arc. There should be seven lines in total,
11 - 6 segments 7 lines.jpg

The lines will not create actual surfaces between the arcs. To create the surface, you need to draw diagonals inside the frame of each segment. The pic below highlights one of these diagonal lines you need to draw. This will split the segment into two triangles which will now form a surface.
12 divide the segments.jpg

Unhiding the fuse panels shows you what the skin will look like.

13 view with model.jpg

Now to unfolding and flattening. The unfolding tool I use is simply called "Unfold Tool". I have not tried others as this does what I need it to do. Just follow the instructions to install this tool (you will probably need to restart Sketchup for the tool to appear in the menu).

Before starting the unfold, draw a rectangle on the floor of the model. This will be the target for the last unfold operation which will flatten the piece onto the horizontal surface.

14 add a rectangle to the floor.jpg

Now zoom into the center of the piece to unfold so that you can clearly see each adjacent panel. Sometimes I find if I am zoomed too far out, I cannot cleanly select the next panel in the series. Select Unfold Tool from the Plugins menu and click on each adjacent panel, starting on the outer panel on one side of the piece, and working your way to the other side.

15 starting the unfold.jpg

When you have selected the last panel, zoom out, select the Unfold Tool from the Plugins menu again, and click on the rectangle we drew earlier. This will leave the unfolded piece on the horizontal.

16 last click on horizontal.jpg

This is what the piece looks like from above (click ctrl-U to look down from the top).

17 look from the top.jpg

We don't need those diagonal lines anymore, now that the piece is flat, so you can select them and delete them.
18 select diagonals for deletion.jpg
19 final unfold piece ready for export to dxf.jpg

Now that you have your flattened piece, time to export it as a .DXF file and then import it into software that can print it as a .PDF. I followed the article "Creating Plans from SketchUp model - Free!" by thatjoshguy to find the software and use it - it works really well.

Hope this has helped.

DamoRC
 

DamoRC

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Maiden!

So I decided to cut some vents in the canopy to relieve the air restriction issues. These new "ducts" relieved almost all of the restriction. I am not ecstatic with the look but, on the bright side they also work as a convenient carrying handle :D

New Cutouts.JPG

Maidened this build today. DamoRC Jnr and I have not flown for almost a year, so we need to get some practice in. All in all the maiden went well. I launched it like a noob but still managed to keep it in the air and get her trimmed. She is twitchier than I remember but this just could be rusty thumbs. I think it may be a little faster than I remember, but that could be a rusty memory. Short vid of maiden launch and one fast pass.


Managed to christen the nose a little on the first landing.

IMG_2500.JPG
 
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AkimboGlueGuns

Biplane Guy
Mentor
HEY! A diamond that survived a maiden! Really nice job on this one, and you don't look all that rusty to me. That was some nice flying. I've got to start looking at EDF's now. Between this and the 3Dlabprint MiG that's coming out soon I've gotten the jet bug.

Also, that racer you're drawing up looks really interesting. It would look awesome on floats. :p
 

DamoRC

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Thanks AkimboGlueGuns! I just haven't figured out where the best trees are at this new field.

Well spotted on the racer :). Yep - it should be on floats, just not sure if I am going to take it that far. Trying to design some "score-and-fold" type designs. This is the current sketchup of the MC-72. I haven't got as far as cutting foam for this one.

MC-72 Sketchup.jpg

Also trying the approach for a GP-5 racer which I have started to mock up in foam

GP5 Proto.jpg

IMG_2501.JPG
 

FoamyDM

Building Fool-Flying Noob
Moderator
I always thought there was a tool in Sketchup that would connect the cross sections... I see now it was a manual effort. I think that MAY have been the piece I was missing.... Let me work something up and I'll get back to you.

Have you given any thought to doing the front section like the FT-Viggen (modular replacement to save the body during a crash?
 

DamoRC

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Have you given any thought to doing the front section like the FT-Viggen (modular replacement to save the body during a crash?

Definitely thought about this and, to some extent, this feature is already there. The nose is a 12 inch long individual component. If you installed it with tape instead of gluing it on like I have done, then if you lawn-dart it you could easily remove the nose and tape on a new one. Although the nose is not specifically designed to be a crumple zone, my experience has been that it does tend to give up before the fuselage.

Of course, this helps with the lawn-darting episodes. Doesn't work so well for trees where, as you can see, the nose can come out unscathed.

IMG_0872.JPG
 

Aviator08

Flagstaff,AZ
Definitely thought about this and, to some extent, this feature is already there. The nose is a 12 inch long individual component. If you installed it with tape instead of gluing it on like I have done, then if you lawn-dart it you could easily remove the nose and tape on a new one. Although the nose is not specifically designed to be a crumple zone, my experience has been that it does tend to give up before the fuselage.

Of course, this helps with the lawn-darting episodes. Doesn't work so well for trees where, as you can see, the nose can come out unscathed.

View attachment 84913

OUCH. :(
 

FoamyDM

Building Fool-Flying Noob
Moderator
Nice! :)

It almost looks like you ran it over with a mower, thinking, "no need to move it, we'll mow around it. Here, hold my beer."

the design looked sharp.