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

[DamoRC]

Introduction
I first came across a picture of this a couple of years ago and was immediately smitten with its good looks and “pointyness”.

The original is produced in kit form by the French company, Aviation Design. It is a 97 inch wingspan, turbine powered jet capable of 200 MPH. The kit costs approximately $3000. They have recently launched the Mini Diamond which is also turbine powered with a wingspan of 72 inches.
I started building my first attempts at this at the end of 2014. I had reasonable success with pusher versions and, based on some encouragement from the forum, moved to an EDF design using the Grayson Hobbies Viggen 70mm EDF kit. Work / life took over for a while but with the announcement of Flite Fest West 2017, I re-visited this plane with a view to making plans and a build log available.
Other folks have scratch built this plane. Lockey’s RC has plans available for a version called the “Zirconia” (clever name) Also, Dragon Hobby is selling a 90mm EDF version called the “Dymond”.

Design
There are no good quality three views available for this plane and so I resorted to using images from the internet and from Aviation Design’s website to help construct the outline of the plane in Sketchup. The original has smooth curved lines which I found difficult to deal with and so I went with a more angular approach while trying to maintain key features of the shape and dimensions. Some key differences between this design and the original are that the wing is set further back in the plane and I reduced the scale height of the side profile and the height of the vertical stabilizer. The wing adjustment was originally made to overcome issues I had trying to balance pusher versions of the plane. But I liked the new position and kept this change because I think it makes the plane look more aggressive.

Plans
A huge “Thank You” to thatjoshguy for his excellent article – “Creating Plans from Sketchup Models – Free!”. This was invaluable in finding free applications and extensions that can be used to create PDF plans from your Sketchup model. I laid out the PDF so that the pages for each part were self-contained and you only need to join pages in one direction (I always had problems with FT plans trying to tape together all of the sheets in two directions and keep everything 100% aligned).

Build
I think this is an intermediate level build. It uses many standard Flite Test concepts but includes the liberal use of an iron for wide bevels and the Pods take some time and patience to put together.

Flying
I think this is an intermediate level flyer. No terrible tendencies but it’s not a “floaty” plane either.

Enjoy!
I would love to see other folks build and improve on this, e.g. adding landing gear, a speed wing etc.

 

[DamoRC]

Plans (Tiled only) attached.
Note These are version 3 of the plans and the zipped file contains a tiled pdf, the DoubleCAD XT file (which you can edit and create different PDF versions), and the Sketchup file with the 3D model and flattened pieces).

View attachment Diamond 70mm EDF Rev 3.zip

If you have any issues or questions post it in this thread or PM me.

This was the state of the build on 21st March, 2017.

Just needed adding control hardware, ESC and Rx, and some color.



And this is a pile of prototype pieces built to work out the bugs in the plans

 

[DamoRC]

Wings

The plans have a single copy of a wing panel, you will need four panels in total. The markings on the trailing edge should be transferred to both sides of the panel, on the inside they mark where the wide bevel is needed, on the outside they show where to cut the control surfaces.



Wide bevels are added using an iron set a low heat. I could never make these with a blade and so I use the iron which works pretty well.

Line the piece up with the workbench edge...



...and move the iron across and back the area to be bevelled, holding a slight angle. Adjust the angle as you iron so that the bevel creeps forward toward the line while becoming sharp at the trailing edge.



The final bevel looks pretty good.



Paper is removed from the spar line forward.



Turn the panels over and tape them together along the leading edge.



Turn the now joined panels over and using a crush technique "bevel" the leading edge for folding the wing.



Mark the spar line at the edge of the foam a the tip and root to aid in placing the spar. The spar is 2 layers of foam, 1/2 inch wide. Glue the spar in place.



The spar is reinforced with paint mixing sticks cut to height of spar.



Create a pocket for the aileron servo and glue in place (sorry - no pic for this step)

Fold and glue the wing first to the spar (let this set) and then glue down the trailing edge bevel.



Cut out the aileron, bevel the edge, and re-attach with tape.



After building the second half of the wing, add some central spars (again, paint mixing sticks) to help join the wings and strengthen the root.



Then glue together and tape the join.

 

[DamoRC]

Fuselage

There are three pieces needed to make the fuselage, the bottom plate, the upper fuse piece (which is the top and sides of the fuse), and the intake ducts piece.



Because there are no right angles between the sides and top and bottom plates (except for the tail end of the fuse), you will need the bottom plate cut and prepped to help set the angles for the sides. The bottom plate has extra wide paper margins to allow you to more easily test fit the upper piece while you are gluing it.

When cutting the bottom plate, score the center crease mark as you will need to bend it out of the way when gluing. Also cut the hatch as indicated but don’t fold it out. The hatch is tiny in the plans – you can make it bigger if you wish. It is built into the bottom plate because I could not come up with an easy solution for a top hatch which did not destroy the deck lines.

When cutting the upper fuse piece cut but don’t remove the wing cutouts and the EDF intake cutout.

The upper fuse has a typical B-fold at the rear. The front is also B-foldish in that the sides are glued to the sides of the top plate.

Starting with the rear, set and glue the B-folds between the sides and the top plate while using a dry fit onto the bottom plate to set the angles, making sure the top plate is level (note - the picture was taken at a weird angle - the top plate here is indeed level)



Then repeat the process with the front of the fuse, again using a dry fit to the bottom plate to set the angles.



Insert the intake duct piece as shown. You will need to put a shallow bevel on the ends of the piece so that they fit flush to outside of the side wall.




Once you are happy with the fit, glue the intake duct piece first to the sides and then to the top plate

Before attaching the bottom plate I added some tape and Velcro to hold the battery.



Glue the upper fuse piece to the bottom plate. Do the rear first and then the front. Trim off the excess paper from the bottom plate and remove the wing and EDF intake cut outs.

 

[DamoRC]

EDF Housing

The EDF setup uses three pieces, the housing, the mounting plate, and the thrust tube.

Unfortunately, I don’t have pictures of the mounting plate and thrust tube assembly, but they are basically the same setup as the Viggen EDF unit build.

One tip is that when preparing the mounting plate, mark the piece out on a piece of foam that is approximately 1 inch wider all around and only cut out the central hole for the EDF. The finished piece is quite fragile so if you try to get it on and off the EDF while you test fit, it will become creased and might crack. When you have the EDF hole cut, test fit it onto the EDF until you can put it on and take it off easily. Then you can finish cutting the part, fit it, and glue it onto the EDF unit.

The thrust tube is made from poster board and the plan includes a guide line to show you how much to wrap the ends around to make the tube. The wide end of the tube fits on the EDF – this can be tricky and you might need to “thread” it onto the EDF twisting it slowly around until it’s actually in place. Once on, try to pull it onto the EDF so that there is at least ¼ to 3/8ths of an inch on the EDF. Then, making sure it is pointing parallel to the EDF body, tape it in place.

The EDF holder piece is pretty straight forward. Score where indicated on the plan and then widen the creases with a skewer or similar. Note that there is a little section of B fold between the bottom and adjacent side plates to help square the piece off and make a good fit to the fuse. Also note that the tab cutouts are “blind”, they are only score cut and you just remove the inner paper and foam so that you don’t see the mounting plate tabs when the unit is fully assembled.



Test fit the piece by wrapping it around and holding it on the work bench.



Also test fit it against the rear of the fuse to make sure it fits well. Once you are happy, glue the B-fold and bottom plates together.

Insert the EDF and thrust tube into the holder. You are looking to check the fit of the mounting plate and tabs into the housing and you are also checking the clearance the thrust tube has at the back. The tube might be a little tight as you try to fit it and it may take on the octagonal shape of the rear of the housing.



To correct this, pinch and squeeze each side of the housing outlet to soften the foam and give it a rounder profile. Do this until the thrust tube exits the housing and maintains a circular shape.



Once you are happy with the entire fit, glue the mounting plate into the unit (don’t forget to pull your EDF wires up through the cutout!).



You can then glue the EDF unit onto the fuse.

 

[DamoRC]

Vertical Stabilizer

The vertical stabilizer is full foil and is built just like the wing panels.

Cut out the panel and mark and score where indicated in the plans. The iron rears it's ugly head again for this piece, using it to bevel the trailing edges of the foil.



With bevels made, remove the paper from the spar to the leading edge score cut. Note, I am using the "new" white foamboard and sometimes the paper does not come off as cleanly as it did with the old stuff.
Crush a leading edge bevel into the foam.



Glue in the spar (which is two layers of foam, 3/8 inches wide). Make sure that the spar doesn't interfere with the tabs at the root (or you can just trim it afterwards).



Now fold the wing and glue down. You will need to glue the spar and bevels at the same time (you could try the spar first, but its hard to get glue into the bevel after the wing is glued at the spar). It is probably a good idea to practice the fold a few times because it takes quite a bit of pressure to hold the glued bevels down fully.



Now test fit the piece on the fuselage. The first thing you should notice is that the EDF wires interfere with the fit (if you don't notice this, you forgot to pull through your EDF wires )



Remove approximately 1/2 to 3/4 inches of the front of the piece to avoid the wires (note that your servo wires also need to exit through the front of the vertical stabilizer).



The key piece of this test fit is to ensure that when the horizontal stabilizer is added, it will have zero incidence to the wing. Here I use a carbon rod taped to the top of the stabilizer to confirm that it is parallel to the bench (the main part of the fuselage is parallel to the wing). There is a slight incline in the rod.



I sanded the tip of the stabilizer a fraction (its difficult to sand the root because of the tabs) and it seemed to help level it off.



Horizontal Stabilizer
The horizontal stabilizer is two layers of foam. You will need to cut out two of the pieces using the single template provided in the plans.



The markings should be transferred to both sides of the pieces. On the outside the mark the wide bevel line and the elevator, on the inside they show where to put strips of extreme packing tape which will be the hinges for the elevator.



Now the dreaded iron again. Use it to bevel the trailing edges of both pieces. Note that the bevels are on the outside of the part.



Then use the iron to round off the leading edges (again, note the direction of the bevelled surface and the rounded edge in the picture to avoid rounding the wrong way(.



On the inside face of one of the pieces place 1 inch wide strips of extreme packing tape along the elevator hinge line. The tape should placed so that the hinge line runs along the center of the tape.



Now glue the two pieces together face-to-face (bevels on the outside!). You can also use sandpaper to clean up the leading edges at this point.



Time to cut the elevators. Score cut along the length of the control surface hinge line. Do this for both control surfaces and both top and bottom of the piece (4 cuts). Now mark a line parallel to each of these hinge lines approx 1/8 inch away from, and on the leading edge side of the hinge line. Using a new or sharp blade, make a bevel cut along this new line, pointing towards the hinge line.



Remove the foam strip that this bevelling operation should produce. Now cut through the indicated control surface line to release the hinge. Work it up and down a few times and if needed, use sandpaper to open the slot so that the elevators don't rub.



Select which face of the piece will be the bottom. This is where we will install the elevator hardware.

First, create an outline on the bottom surface using the tip of the vertical stabilizer as a guide - we are going to remove that piece as a pocket for the horizontal and vertical stabilizers to join.



This attempt is not pretty but it works. Make and install a torque rod don't forget the sleeve to allow the rod to rotate when it is fixed in place





Now add a pocket for the servo, glue it in place and add the control horns and remaining hardware to connect servo, torque rod, and control horns. It's ugly, and I am sure there are better and neater ways of doing this, but it works!





Test fit the vertical stabilizer into the cutout in the bottom of the horizontal stabilizer to mark where you need to cut reliefs for the torque tube and servo wire (the servo wire should enter the top of the vertical stabilizer ahead of the spar). When you are happy with the fit, making sure that the pieces sit square to each other, thread the servo wire (and whatever extension wire(s) you will need) through the vertical stabilizer. Now glue the two pieces together making sure they are square and level.

Here is a pic of the completed tail feathers sitting on the fuse (don't glue them on just yet!).

 

[DamoRC]

Canopy

The canopy is a single piece of folded foam that provides the canopy "look' but also strengthens the joint between the fuselage and the EDF housing and offers additional support to the vertical stabilizer.

Cut the part as indicated on the plans and add all of the score cuts. Widen the score cuts with a couple of passes with a blunt tip or skewer.



Test fold each section to make sure it wraps around evenly and easily.



Glue only the side panels of the sections together to form the piece. There may be gaps at between the sections which you can fill with glue.




Cut approx 1 inch - 1.5 inch off the nose - this is to create an opening for the motor and servo wires.



Now to bevelling. The piece needs to sit flat and flush on the fuselage. You can see that there is a significant foam lip (mostly at the nose) that needs to be removed. Bevel the bottom edge of the piece along the entire length while test fitting to see that the canopy sits flat on the fuse and on the EDF holder.



Pay attention to the fit at the EDF holder - you may need to trim a little here.



If you look down on the tail section of the piece you'll not that there is a lot of foam showing that needs to be bevelled for a good fit to the vertical stabilizer.



An easy way of doing this is to dry fit the piece and bevel it in place with the blade held vertically



When done - dry fit the tail feathers and canopy together to check the fit.



When you are happy with the fit, glue in the tail feathers, making sure the vertical stabilizer is at 90 degrees and pointing straight down the fuselage.

Run your motor and servo wires down towards the front of the fuse and tape in place.



Now glue on the canopy.

 

[DamoRC]

Wing Installation

Before building and adding the nose and turtle deck we need to install the wing. It's pretty straightforward and is like most FT models.



Before sliding the wing into the fuselage you'll need to remove approx 1 - 1.5 inches from the nose because this is a tight fit. Take your time and it will eventually go in. Make sure your servo wires end up inside the walls of the inlet ducts.



Make sure to properly center and square the wing by ensuring the same length between tip and fuselage on both sides (red lines in pic) and that lengths from wing tip to nose of fuselage are the same length also (blue lines). Its worth taking the time to make sure this is as close as you can get it.



Now glue in the wing by laying down beads of glue between the wing and the fuse and working them in with a scrap piece of foam. Make sure to add glue between the top of the wing and the wing cut-out in the inlet duct piece.


Beginning to look like a plane!


Cut a small slot in the top plate of the fuse to run your wires into the hatch area.



Nose

Cut out the piece per the plans and add the score cuts. Remove the foam channels for the B-fold and and widen the score cuts with a skewer. Note there is an extra wide paper margin on one side to help in folding and fitting the free B-fold side.



Remove the tip of the nose as indicated in the plans. (NOTE - the current version of the plans have the tip removed)



Bevel the outer edge starting about one inch from the fuselage side of the nose. The bevel will need to be more extreme (more foam removed) as you move to the tip.



Test fold the piece a few times so that your are happy with the shape and that the tip of the nose (the hardest piece to fold fully) is to your satisfaction. Once this is done, glue the B-fold (both sides at the same time works) and hold tight until the glue sets. Then you can remove the excess paper.



Dry fit the nose to the end of the fuselage. You are looking to ensure that the sides of the nose and fuselage are parallel. You may have to pull both sides outward to get the nose to maintain a shape that fits well with the fuse. Once this is done, glue the nose onto the fuse.



Beginning to get "pointy"




Decking

The decking is made from a single piece of foamboard.

Cut the piece according to the plans and add the score cuts. Widen the length ways score cuts with a skewer to make the piece fold more easily.



You'll need to bevel the sides and the cutout for the canopy.




Check that the front of the decking is aligned well with the nose...



...and that it also sits well around the canopy.



Almost there! Just the wing pods to add.

 

[DamoRC]

Pods

Note: Apologies in advance, this pod build is a bit rough - but you should get the idea.

Print a couple of copied of the pod plans (building them as described below destroys the plan). Pin the plans to an appropriately sized piece of foam board. You can also use a glue stick or something similar.



Using a new / sharp blade, freehand cut the pattern from the foam and score where indicated on the plans. It is easier to cut from the points to the center of the pattern. Don't forget to transfer the line marked in green to the opposite (outside) of the foam - it marks the point at which you align the rear of the pod with the trailing edge of the wing.



Turn the piece over and place a strip of tape across the center (to stop the score cut lines from ripping through the paper).



Turning the piece back over, remove the paper from the foam.



You can either bevel all of the edges now, or do it as shown below, where you just bevel the outside pieces, glue the sides at the center of the pod, and then bevel the "fingers". Make sure the bevel at the end of the fingers is quite shallow to allow the points to come together.





Glue the piece together. You can do this one finger at a time (glueing it to its neighbor) or, as I did here, glue the tips together, then go back and fill the seams with hot glue, scraping away the excess.



Repeat for two pods total!



Aligning the mark with the trailing edge of the wing, glue the pod to the wing tip. Make sure that the pod is pointing straight(-ish) ahead and that it is level with the wing.

 

[JimCR120]

I wouldn't trust myself at the controls of that. I think I could land it like a lawn dart. I wish you well. Keep us posted.

 

[AkimboGlueGuns]

Yay! Glad to see this thing making a comeback. What kind of power do you expect from your EDF?

 

[DamoRC]

@JimCR120

I wouldn't trust myself at the controls of that. I think I could land it like a lawn dart.

I think you would have no problems - it isn't that difficult to fly, just not a beginner's plane. I never lawn-darted it, but I did make an interesting "landing" in a tree with one of the earlier pusher prototypes (see link to video in the signature below).

@AkimboGlueGuns

Yay! Glad to see this thing making a comeback. What kind of power do you expect from your EDF?

Thanks! In the first iterations of the EDF version I was getting ~32 oz static thrust on 4S, pulling ~610 watts. I have not tested static thrust with the current design which now includes a proper thrust tube. I should test this again once I have the EDF and thrust tube installed.

DamoRC

 

[JimCR120]

Ok, your video makes it look much less menacing than the original hyperpointy pic you posted. After seeing you hit the tree, yup, I could do that.

 

[DamoRC]

@JimCR120

After seeing you hit the tree, yup, I could do that.

Now that's funny! Question is, if I was trying to hit the tree, could I have?


@AkimboGlueGuns - did a quick and dirty static thrust test with a fully charged 2200mAh 4S and three runs gave a range of 38-39 oz. This seems to be better than I had seen before and closer to Grayson Hobby's claim of 42 oz. It may be that the thrust tube is working or that without canopy, decking, and wing installed, there is less restriction on the air entering the unit. I'll test again when the build is finished and if it turns out that there is an airflow restriction I'll just punch some holes in it.

DamoRC

 

[DamoRC]

Quick update - the build log (on Page 1) has been updated to include the wing, fuselage, EDF housing and mounting, and the tail feathers. Just the nose, canopy, decking, and pods to go!

So far I have not had to make changes to the plans except for correcting markings, colors, labels etc. All going well she'll be done by the weekend.

Does anyone know if the EDF kit for the Viggen will take 5S or 6S? I know the ESC will handle 6S (but only 60A) but I have no idea if the motor in the EDF will take more than 4S.

DamoRC

 

[DamoRC]

Canopy build added to page 1.

Edit - also added wing installation and the nose build.

DamoRC

 

[DamoRC]

Plans are uploaded! (see page 1).

Decking is on - just the wing pods to add, finish the control hardware and electronics, and she is ready to paint and crash!

 

[planebreaker2000]

Wow!

 

[Aviator08]

Very Cool! Looking forward to seeing it at FF West.

 

[DamoRC]

Thanks to both of you.

@Aviator08 - I am also looking forward to seeing your Tri-motor! I am hoping not to trash this one before FF west.

DamoRC