Avro CF-100 Canuck - Twin 70mm EDF

[DamoRC]

I should be working on the C-130 as part of March Madness, but I get easily distracted. Came across one of these on Youtube, had a couple of 70mm EDFs looking for a home, and thought "Why not?" Andre was considering this plane for a twin 64mm build at one point but I don't know if he made any progress.



They also had a "podless" version (the pod positions could carry a variety of armaments).



So I got to work, originally planning for approx 40 inch wingspan.



At this point, trying to model in a 70mm EDF with an appropriately large exhaust (~85-90% FSA) while having some form of taper at the exhaust, I realized that the plane was going to need to be a bit bigger. By the time I had scaled it up so that the exhaust diameter was fine and the nacelle looked kinda-sorta scale-ish, the plane had grown to a 54 inch wingspan. So it's going to be a bit of a beast. I flattened out the parts and printed them out.



This is what the current Sketchup model looks like.



DamoRC

 

[Zephyr1]

I'm very excited to see how you put the EDFs through the wing! It's something I've thought about doing before but never figure out. Good luck!

 

[DamoRC]

I'm very excited to see how you put the EDFs through the wing! It's something I've thought about doing before but never figure out. Good luck!

I think you may be disappointed

The earlier drawings in the first post were based on a simple plan and profile view, making it look like a mid-winged plane. In reality it is a low wing, so I am gonna totally cheat with the EDF units. The wing will be flat-bottomed, and the EDF housings and fuse are flat-bottomed where they meet the wing. So basically, the plan is to attach the EDF units to the fuse so they share a common flat bottom surface and then the combined units will sit directly on the lower surface of the wing. Only the area from the outboard side of the EDF to the wing tip will have an upper wing surface (and perhaps a fillet to fill the gap between the EDF unit and fuse). Then spars on the lower and upper wing surfaces that go through the fuse and EDF unit to hold the whole thing together. Not pretty, nor elegant, but effective (I hope).

DamoRC

 

[DamoRC]

Starting the build - progress thus far.

Printed out a tiled version of the plans - all 52 pages! Cut and taped the sheets - this is not going to be a low part-count build.




Started with the fuse parts. Each part is cut and scored according to the plans and the scores are widened a little by running a blunt-ish skewer along the cut. Each part also has 2 frames that need to be cut - these are to hold the part shape while the Gorilla glue sets. This is a pic of the fuse parts dry fit into their frames.



At this point the first problem with the parts is observed - look how narrow the tail piece is at the end. Given that this piece is going to hold the double foamboard layer V and H stabs close to the end, I am going to need a little extra GG in here to make sure the piece is strong and stiff.

This is just an example of how the parts look when they have GG added to the score cuts and are then folded and glued together at the seam with hot glue.



Having glued and framed the fuse parts, moved onto the nacelles. Here are the nacelles dry fit into their frames with the fuse parts glued up and drying in the background.



Going to re-use the nacelle frames for the second nacelle, so while the first is drying, moved onto the EDF holder. Order of operations here is important. After marking out the piece, cut the EDF hole first and confirm that the EDF will fit snugly but easily into the hole before finalizing the part. This frame is reasonably fragile, so if you cut it completely and then try to fit the EDF it will warp and possibly split.



Should get the second nacelle setup today and start putting some of the parts together.

DamoRC

 

[DamoRC]

A lot more progress today.

This is the EDF mounted in the rear of the nacelle. This is ready for attachment to the rest of the unit but I want to wait until I have a better idea of where the wiring from the ESC will go. The nacelle is mocked up in the second picture.



The tail feathers were cut, twice for two layers of foamboard for the V- and H-stabs. They were laminated using gorilla glue with various weights applied to keep pressure on the layers.



The V- and H-stabs interlock with each other and to allow the twin elevator servo wires to pass through the fuse reasonably concealed I added some trenching to the V-stab.



Multiple wooden spars were added to the tailfeathers. Although the gorilla glue laminated the pieces just fine, the H-stab had a little flex out near the tips that I wanted to remove and the V-stab has quite a bit of weight to hold up so better safe than sorry.



Then the tailfeathers were installed to the rear-most fuse part.



The fully assembled fuse is pretty long (Baron added for scale)



And this is what is looks like with the two not-quite-finished nacelles.



DamoRC

 

[jabberwockie]

That's looking grand How do you find working with Gorilla glue versus hot glue? Do you prefer it because it gives you more working time? Is there any weight advantage?

 

[DamoRC]

That's looking grand How do you find working with Gorilla glue versus hot glue? Do you prefer it because it gives you more working time? Is there any weight advantage?

Thanks!

I use the GG mostly on these tube type constructions, in the score cuts, because it allows time to get all of the lines done and get the tube mounted up in frames to make sure the shape holds. One dry, its stiffer than hot glue and easier to work (sanding etc). This was the first time I have used it for laminating two layers of foamboard for the V- and H-stab. If its fresh, its easy to work with. For everything else I use hot glue.

DamoRC

 

[FoamyDM]

Wow DamoRC. That looks so good.

So how do you figure out the CG on this untested plane. from the original plane plan, build a glider, balance it at the 1/3 wing chord and chuck? I saw this because my Bloody Black Widow flew. But a little elevator got it crazy. based on the projects I see out of you, you must have tackled this somehow. What do you think?

-FoamyDM

 

[DamoRC]

Wow DamoRC. That looks so good.

So how do you figure out the CG on this untested plane. from the original plane plan, build a glider, balance it at the 1/3 wing chord and chuck? I saw this because my Bloody Black Widow flew. But a little elevator got it crazy. based on the projects I see out of you, you must have tackled this somehow. What do you think?

-FoamyDM

Thanks FoamyDM!

I typically use one of the online CG calculators to get a guestimate and then go pretty conservative on the maiden, maybe 10 to 15 degrees nose down when balanced on the guestimate. This seems to work for me. I never do the chuck glider thing (I probably should).

Thinking of the CG after finishing the fuse last night, I may have to reconfigure the nacelles. The EDFs are going to be behind the CG, and coupled with a heavy tail, I might have problems getting her to balance even with the 2 x 2200 4S batteries that I plan on using. I would like to avoid having to add dead weight as she is already heading for around the 4.5 -5.0 pound mark AUW. I could move the EDFs to the next section forward in the nacelle, but then I’ll be losing thrust. So I am going to wait until the wing is built before gluing up the nacelles completely and see if I can get her balanced.

DamoRC

 

[DamoRC]

Getting closer...

Added a nose cap, canopy (which doubles as the hatch), wired the EDFs, mounted the nacelles to the fuse, and got half a wing finished.



DamoRC

 

[Morgan]

Totally love this thing.can't wait to see this fly!☺

 

[aelflyer]

Impressive, DamoRC!

 

[Grifflyer]

Awesome work so far Damo

 

[DamoRC]

Thanks guys!

Almost done, finished the wing which includes a CF tube spar, cut reliefs into the fuse and nacelles, and mounted the two together.



AUW now looks like it will be somewhere in the 4-4.5 pound mark.

Waiting on HK for a pair of matched ESCs (I think they are way behind processing orders because of the warehouse sale) and the weather has been pretty wet so no real chance to finish or fly for a couple of weeks I think. Planning on doing a metal type finish like the Okha with some red and black like these (although I am not going to add the wing tip pods).




DamoRC

 

[Ketchup]

Nice job. I obviously can’t fly either because of rain but I might work on my mustang. I will wait to see this at the field when it doesn’t rain though!

 

[DamoRC]

Thanks Ketchup!

Weather held up for most of the day so managed to get some painting done.

One thing about the metallic paint, it reveals all of the flaws in the build because the foamboard comes up a little dull but remnants of hot and gorilla glue turn up bright and shiny!

All it needs is a few RCAF roundels and maybe some detail on the nacelle.




After spending all of this time designing, building, and painting, only today did it dawn on me that I hadn't checked whether the thing would fit in the car.

Thankfully, after a complicated process, I was able to get it to fit. At one point I thought I was in a chapter from Dirk Gently's Hollistic Detective Agency, having gotten the plane to fit, I could not get it out again. But it's all good now.



DamoRC

 

[Grifflyer]

If the plane didn't fit...

but anyways it looks GREAT! Quick question what are you're specs? I remember reading something about 40 inch wingspan but it looks much bigger than that.

 

[DamoRC]

If the plane didn't fit...

but anyways it looks GREAT! Quick question what are you're specs? I remember reading something about 40 inch wingspan but it looks much bigger than that.

Original drawings were for a 40 inch wingspan. Then I noticed that the exhausts of the nacelles were tiny compared to what I would need for a 70mm EDF. So I compromised between a larger wingspan, which is now 54 inches, and not quite scale exhaust (it’s good for the 70mm EDF, but still not as narrow as the scale drawing).

This might make a nice 40 inch wingspan for 50 mm EDFs. If anyone has a pair of 50mm EDFs looking for a home I can scale down the model and post plans.

DamoRC

 

[Grifflyer]

Original drawings were for a 40 inch wingspan. Then I noticed that the exhausts of the nacelles were tiny compared to what I would need for a 70mm EDF. So I compromised between a larger wingspan, which is now 54 inches, and not quite scale exhaust (it’s good for the 70mm EDF, but still not as narrow as the scale drawing).

This might make a nice 40 inch wingspan for 50 mm EDFs. If anyone has a pair of 50mm EDFs looking for a home I can scale down the model and post plans.

DamoRC

Wow that's pretty big, and too bad I only have one 50mm edf

 

[Ketchup]

Nice photography, you said that the paint shows, but nobody will notice, except for ME.