Edmonds Aerospace CiCi build

[Rktman]

I’ve always liked the looks of the Edmonds Aerospace CiCi, and it’s a quick, simple build that practically flies right out of the box with a minimum of trim fiddling. In fact, I’m a fan of all the Edmonds Aerospace gliders, but I’ve never built one from scratch because those interlocking tabs and slots that make assembly so idiot-proof are also really tricky to cut accurately by hand so that they jigsaw together right.

That said, I wondered how doable it would be to duplicate those shapes by hand if I had a specialized hobby knife blade. I found this on the McMaster-Carr website. It’s a #17 Xacto precision chisel blade, 3/8” wide by 1.5” long. Here’s the link to it if interested: https://www.mcmaster.com/35435A87/




If things work out, I’ll know I can move up to the Twinsee or Geminee that have more complicated joints.
Well, here goes.

 

[Rktman]

Whew! Main wing done. Encouraged by how well the new chisel blade is working out.



The only thing that might slow things down is having to carefully cut out all those small notches and tabs accurately. This would otherwise be a fast build.

 

[Rktman]

I’m sold. This chisel blade cuts real sharp angles, and the edges are impressively square. I was able to cleanly cut out the tab in the pylon as well as the small 1/8” wide x 3/8” long hole that the pylon tab fits into in the forward canard wing so they fit together perfectly.






I decided to cut tabs just a tiny bit oversize and the slots they fit into a little bit on the small side. I figure it’s better to do some touch-up sanding if needed rather than risking a sloppy too-loose fit.

 

[Rktman]

All parts cut out and ready to assemble. Dipped the edges of the main wings, canard and rudders in thin CA for strength and ding protection.



Will be taking a Christmas build break and be back in a day or so to finish things up. Have a good holiday everyone!

 

[Rktman]

Canard wing glued in place and filleted.




Main wing attached.

 

[BABAR]

I commend you on your cutting skills!

I wonder however if the only really critical factors are the canard vs main wing angle and making sure the rudders are straight. The “tab in notch” factor almost guarantees the rudders are straight in factory-cut balsa, but otherwise just makes it a really EASY build when it comes pre-cut.

My CiCi2 sustainer sailed away, my booster snapped when it hit a fence on landing. A carbon fiber rod or strip reinforcing the fuselage wouldn’t hurt.

 

[Rktman]

Note: when using this “tongue and groove” type of construction, cutting inside, outside, or right on the template lines can make a huge difference depending on how thick those lines are. This tab ended up hanging out beyond its slot because I cut outside the template lines a little too generously and it made this much of a difference. Better that than being too short though. A single-edged razor blade and some sandpaper will easily fix it.




Since reviews have mentioned that the ejection charge has a bad habit of sometimes snapping off the motor pod or breaking the fuselage near it, I punched two vent holes 180° apart on either side of the motor tube 3/8” from the forward end. The nose cone shoulder will partially block the vent holes anyway (they’re supposed to per Rob Edmonds) so there’s no concern that the motor won’t eject.




Almost done!
Just waiting on the nosecone I ordered a couple weeks ago. USPS is having a hard time of it, it’s been “on its way to the next facility” for days now, no location, no ETA.

 

[Rktman]

I commend you on your cutting skills!

I wonder however if the only really critical factors are the canard vs main wing angle and making sure the rudders are straight. The “tab in notch” factor almost guarantees the rudders are straight in factory-cut balsa, but otherwise just makes it a really EASY build when it comes pre-cut.

Thanks. Just for fun I wanted to see how closely I could replicate things. Would’ve preferred laser cutting everything but it’s not worth the expense for something as simple and small as this. I was using this as “practice” for either the Edmonds Geminee or CiCi 2-stage. Agreed nothing was critical except the canard angle (which really doesn’t require precision cut corners).

On the Edmonds CiCi 2-stage, the booster stage motor mount has a dovetail joint, probably for strength and alignment. Now I know I can replicate that critical joint even if I don’t bother with the other joints.

My CiCi2 sustainer sailed away, my booster snapped when it hit a fence on landing. A carbon fiber rod or strip reinforcing the fuselage wouldn’t hurt.

Good advice. I have some decently hard balsa I’ll use for the fuselage. Or possibly basewood. Uber lightness isn’t a concern since it’s a sport model and my flying fields aren’t all that big.

 

[BABAR]

I found the Twinsee was a better performer than the Geminee

 

[BABAR]

Oh yeah, you are already probably all over this, but I recommend two vent holes, one on each side, to prevent any net lateral force on ejection that might snap the fuse.

 

[Rktman]

Oh yeah, you are already probably all over this, but I recommend two vent holes, one on each side, to prevent any net lateral force on ejection that might snap the fuse.

Yup. See #7.

My Jet Freak was reduced to tiny fragments of balsa and cardboard last year from the (probably malfunctioning) shotgun blast of the ejection charge. I just finished a 1.33 upscale version with two vent holes 180 degrees apart. Just wanna ensure stuff like that never repeats itself.

 

[Rktman]

Nosecone finally arrived! Should be able to wrap it up soon. Some sealer, sanding, and paint should do it.

 

[Rktman]

Had a narrow window of opportunity to paint (the motor pod) yesterday, so I took it. Paint’s still a bit tacky but no matter, I won’t be able to fly it anytime soon. Speaking of, I took a few trimming tosses and it seems to be somewhat nose heavy. I wasn’t expecting that, but rather than adding a bunch of tail weight and risk throwing off its launch stability, I’m going to see how it flies first.



Overall it feels a bit heavy for a glider its size and would consider using 1/8” hard balsa for its fuselage instead of 3/16”, and 3/32” balsa for its main wing instead of 1/8”. That would trim its weight down to something more reasonable. Also adding a carbon strip to either side of the fuse from the pylon to midway back would solve the snapping problem that some reviewers mentioned.

Having said that, though, I realize the CiCi was meant as an easy to assemble and sturdy sport glider that even kids could build, and that it was never intended as a competition flyer. Having primarily small flying fields, I like the CiCi because it’s a simple to construct fun glider that I won’t have to worry about thermalling away.

 

[aerostadt]

I would think that with a B4 it will go far away.

 

[Rktman]

I would think that with a B4 it will go far away.

Guess I'll have to put it on a long leash. Or train it to return when I whistle.

 

[Ez2cDave]

Speaking of, I took a few trimming tosses and it seems to be somewhat nose heavy. I wasn’t expecting that, but rather than adding a bunch of tail weight and risk throwing off its launch stability, I’m going to see how it flies first.

Hi, Eric !

I'm very surprised that the glider is nose-heavy, given its design . . .

Possible "incidence" issue ?

Dave F.

 

[Rktman]

Hi, Eric !

I'm very surprised that the glider is nose-heavy, given its design . . .

Possible "incidence" issue ?

Dave F.

I'm even more surprised, given most of the mass is at the rear, but I made real sure the canard and main wing angles were exact. Keeping an open mind, as I've read a review or two that mentions the glider seemed nose heavy when hand tossed but glided level after being launched.

 

[Ez2cDave]

Keeping an open mind, as I've read a review or two that mentions the glider seemed nose heavy when hand tossed but glided level after being launched.

That seems odd to me . . . I have seen Gliders hand launch beautifully, but fail dismally in flight, but not the opposite.

Dave F.

 

[BABAR]

Had a narrow window of opportunity to paint yesterday, so I took it. Paint’s still a bit tacky but no matter, I won’t be able to fly it anytime soon. Speaking of, I took a few trimming tosses and it seems to be somewhat nose heavy. I wasn’t expecting that, but rather than adding a bunch of tail weight and risk throwing off its launch stability, I’m going to see how it flies first.

View attachment 445326

Overall it feels a bit heavy for a glider its size and would consider using 1/8” hard balsa for its fuselage instead of 3/16”, and 3/32” balsa for its main wing instead of 1/8”. That would trim its weight down to something more reasonable. Also adding a carbon strip to either side of the fuse from the pylon to midway back would solve the snapping problem that some reviewers mentioned.

Having said that, though, I realize the CiCi was meant as an easy to assemble and sturdy sport glider that even kids could build, and that it was never intended as a competition flyer. Having primarily small flying fields, I like the CiCi because it’s a simple to construct fun glider that I won’t have to worry about thermalling away.

Like the paint scheme, less is more, especially with gliders.

What did your nose cone weigh? I am used to kit bashing, but I think the Viking nose cone (even without the plug and with 1/2 the shoulder cut off) was on the heavy side. Needed a good bit of tail weight.

I have heard about the, “Let’s see how it flies,” glider trimming technique, but in a bird that in test tosses is nose heavy, I’d be a bit nervous (tail heavy wouldn’t bother me as much.

Hope I get to fly tomorrow, winds supposed to be 6 mph, that’s decent for my area.

 

[Rktman]

Balsa nose cone weight was 0.78 gram, less than an equal volume of whipped cream. Pretty weird that the forward end is heavier when most of the material and mass (thicker fuselage section, main wing and rudders) are at the rear. Even the balance point seems to be a bit forward of where I expected it to be. Double checked the canard and wing angles with my template pressed to the finished glider and it's absolutely accurate. Also checked the tracing to the photo and it's accurate as well. Canard and pylon balsa doesn't have any heavier grain lines running through them. The fuselage might, though it's too thick for me to see through even with the heavy duty flashlight I have.

Worse case scenario is that it lawn darts. If it's relatively undamaged I'll try sanding a very slight airfoil into the canards, fly it to see the effect, and continue with very small airfoil changes if needed. 2nd choice would be to cut some flaps into the trailing edge of the canards and try tiny amounts of negative incidence (1/2° at a time, not to exceed 2° total to prevent looping). Should be interesting to see what happens.

If anyone has alternate suggestions feel free to jump in, I'd be interested in hearing about them.

 

[Ez2cDave]

Balsa nose cone weight was 0.78 gram, less than an equal volume of whipped cream. Pretty weird that the forward end is heavier when most of the material and mass (thicker fuselage section, main wing and rudders) are at the rear. Even the balance point seems to be a bit forward of where I expected it to be. Double checked the canard and wing angles with my template pressed to the finished glider and it's absolutely accurate. Also checked the tracing to the photo and it's accurate as well. Canard and pylon balsa doesn't have any heavier grain lines running through them. The fuselage might, though it's too thick for me to see through even with the heavy duty flashlight I have.

Worse case scenario is that it lawn darts. If it's relatively undamaged I'll try sanding a very slight airfoil into the canards, fly it to see the effect, and continue with very small airfoil changes if needed. 2nd choice would be to cut some flaps into the trailing edge of the canards and try tiny amounts of negative incidence (1/2° at a time, not to exceed 2° total to prevent looping). Should be interesting to see what happens.

If anyone has alternate suggestions feel free to jump in, I'd be interested in hearing about them.

Eric,

How about inserting an angled straight pin into the Fuselage ( cut the head off after installation ) and doing some "catapult" testing ( less risk than powered flight and you can vary the Ascent Angle over a wide range ) ?

Dave F.

 

[Rktman]

Eric,

How about inserting an angled straight pin into the Fuselage ( cut the head off after installation ) and doing some "catapult" testing ( less risk than powered flight and you can vary the Ascent Angle over a wide range ) ?

Dave F.

I like that idea. I still have the dowel and elastic sling that I used with another much larger canard (couldn't get that one up high enough). The CiCi is small enough that I should be able to (and without risk to anyone else's possible safety). Saves me some motors too.

 

[Rktman]

Mystery solved. Poked a pin into the fuselage aft end and it went in easily. Had a tough time pushing it in on the forward end. Apparently there's a denser grain running through the balsa at the front of the fuselage. No design flaw, just luck of the draw. Could've happened even if this were a kit.
From now on, general Rule #1 when glider scratch building will be to orient the heavier end of a fuselage stick to the rear for canards.

 

[Ez2cDave]

Mystery solved. Poked a pin into the fuselage aft end and it went in easily. Had a tough time pushing it in on the forward end. Apparently there's a denser grain running through the balsa at the front of the fuselage. No design flaw, just luck of the draw. Could've happened even if this were a kit.
From now on, general Rule #1 when glider scratch building will be to orient the heavier end of a fuselage stick to the rear for canards.

Eric,

Good deal . . . Glad you solved the mystery !

What are your plans . . . Tail Weight or Canard Flaps ?

Dave F.

 

[Rktman]

Eric,

Good deal . . . Glad you solved the mystery !

What are your plans . . . Tail Weight or Canard Flaps ?

Dave F.

Sand a very slight airfoil into the canards, catapult-launch with elastic to see the effect, and continue with very small airfoil changes if needed. Or cut some flaps into the trailing edge of the canards and try tiny amounts of negative incidence (1/2° at a time, not to exceed 2° total to prevent looping it into the ground when launched). Although Edmonds designed the pylon with a negative 3° down-cant, I still want to be conservative with the changes.

 

[Ez2cDave]

Sand a very slight airfoil into the canards, catapult-launch with elastic to see the effect, and continue with very small airfoil changes if needed. Or cut some flaps into the trailing edge of the canards and try tiny amounts of negative incidence (1/2° at a time, not to exceed 2° total to prevent looping it into the ground when launched). Although Edmonds designed the pylon with a negative 3° down-cant, I still want to be conservative with the changes.

Eric,

You could cut small "adjustable flaps" from an aluminum Soda Can and glue them to the Canard . . . Bend to adjust !

I suspect that air-foiling the Canard would not give sufficient correction, except at high glide speeds ( effectiveness would diminish with slower Glide Speeds )

Dave

 

[BABAR]

Options for dropping nose weight

Shorter BT

Replace the doubled over pylon and fuse with integrated one.

Shorter pylon

Maybe put launch lug on the rear between the fuse and the flat wing.

 

[Rktman]

Options for dropping nose weight

Shorter BT

Replace the doubled over pylon and fuse with integrated one.

Shorter pylon

Maybe put launch lug on the rear between the fuse and the flat wing.

Or build another CiCi.

 

[Rktman]

Update

I finally got around to addressing the nose-heavy problem with the CiCi (had to counterweight the aft end with a whopping 6.72g — about a quarter oz — lump of clay, a bit much for such a small glider). I was able to disassemble the CiCi and save its main wing and motor pod/pylon assembly.




I made a new fuselage based on the original CiCi kit with the integrated pylon and grafted my old pylon onto it (the grain direction is oriented in a stronger direction). Just to ensure it won't snap from the ejection charge (often noted in old Rocket Reviews flight reports) I drilled a small hole from the fuse up into the pylon and inserted a 0.060" carbon fiber rod for reinforcement.





I fabricated another canard wing out of the lightest balsa I could find in my stash, as the old one was made of pretty dense (read heavier) balsa. Every bit of weight I can shave off the forward end helps. To that end I also rounded the square edges off the fuselage from the front to about ¾ of the way back.

Here she is rebuilt. The dark strip on the fuselage top is a thin carbon strip to reinforce the vulnerable area that often reportedly snaps.



To be continued…

 

[Rktman]

Did some hand trimming. Rebuilding the fuselage didn’t change anything. I continue to have the nose-heavy condition. I still had to counterweight the aft end with a huge lump of clay just to keep it from pitching into the ground after a few feet. From all the old reviews I’ve read, no one mentions this problem, and from a design standpoint, the forward end should actually be a lot lighter than the aft section (the 1/8” balsa used for the main wing is quite a bit heavier already than the thinner balsa used for the canard wing).

I'll need to take it for a test flight and see how it does.



To be continued…