CiCi 2 Edmonds two stage black powder gap stage

[BABAR]

Okay, photo order is backward

The one on the bottom is what I figured I’d use, it didn’t think it needed the full length. So I cut a shorter piece.

Then I got to thinking that alignment is critical between the two glider sections. Since I am hand cutting the balsa, I don’t think I can get the “jigsaw” like precision that makes the kits that come precut such a joy to build, you just about have to work to screw it up. I have to rely on other means, such as balsa cheaters, and if went back to cutting it out as per original plan, or at least close, as the longer it is (in combination with a properly placed cheater on the body tube) the longer the length of the aligned surfaces, and the better (hopefully) the alignment.

The Canards aren’t a big deal if they are off a bit, but because the RUDDERS are on the outer edges of the wings, they and the wings need to be perfect, and that requires the STRUT connecting the booster fuselage to the booster tube (which will attach to the sustainer) to be perfect. We will see.

I have a temporary piece that I will use for alignment for gluing the strut between the fuse and the body tube to hopefully keep things straighter. I am probably overthinking this.

 

[BABAR]

This was my final jig rig, with a piece of balsa running down the tube inside to line up with the fuselage, and the extra piece between the fuse and the body tube (not glued) to keep the spacing right.

Also, the instructions say 3/16 for the fuselage, but 1/8 for the motor mount. I just made the motor mount 3/16 as well to keep it straight.

 

[BABAR]

VERY cool glider! Planning on building the simple Cici version myself as soon as I can get my hands on some decent balsa.

Interestingly, the CiCi2 sustainer plans are DIFFERENT from the plain single stage CiCi.

https://www.spacemodeling.org/jimz/other/edmonds_cici.pdf


You may want to look at the CiCi2 plan, as if you later decide you want to add the booster, I am not sure it will work with the CiCi single stage. However I am pretty sure the CiCi2 SUSTAINER could be flown as a SINGLE stage, except you will have to add a launch lug (the CiCi2 only has one—- on the booster, but I will also probably add one to sustainer so I can fly it single stage.)

Also on the CiCi single stage, the Person who posted the plans (God bless him or her!) also put in some HANDWRITTER dimensions that I don’t think were in the original instructions (wouldn’t be needed as everything was precut.) dimensions on the CiCi2 are TYPED in, but I think THEY were also added later (again, why put them in when everything is precut.). But the single stage CiCi and CiCi2 sustainer dimensions don’t match.

On the single stage,
the fuse is 3/16
The wing and motor mount are 1/8
The canard and rudders are 1/16

The body tube is 2 1/2”

The nose cone is balsa, described as 1 3/4” long with 1/2” shoulder

On the CiCi2, the sustainer
The fuse is 3/16
The wing is 1/8. (The motor mount is integrated as a single piece with the fuse)
The canard and rudders are 3/32

The Body tube is only 2”. (There’s a reason for the difference, you add a tape ring, I guess Mr. Edmonds ASSUMED you would use 1/2” tape)

The nose cone is described slightly differently than above, 1 1/2” long with 1/2” shoulder.

I just decided I’d go with 3/16 for the fuselages, and 1/8 for wing, canard, and rudders.

I was just planning to use repurpose a Viking plastic nose cone for the balsa, but this may unbalance the sustainer glider. Robert Edmonds had such (to my experienced well placed) confidence in his design that he didn’t recommend any preflight testing or trimming. I am thinking that plastic is going to weigh a bit more than balsa, plus I am not going with the recommended balsa thicknesses. So mine may need some trimming

 

[BABAR]

More work with balsa fillets/cheaters. A problem I am struggling with is sanding them down after attachment. I think that the problem is the glue. They need to be attached with minimal glue as the glue is hard to sand. In this case may not matter much, I am putting launch lugs in both booster and sustainer, so I can fly as dual stage and single, so the cheater will be mostly covered anyway. I do think the cheaters make alignment better and easier, and I think it likely makes attachment faster and stronger. Add very little weight, but if I can’t sand them down or cover them with a smooth fillet, they likely bump up the drag a bit.

 

[BABAR]

Okay, I clearly understand the holes in the booster section, they release the cool gas in the lumen of the tube when the zero delay motor burns through, allowing the hot gas to move forward to illuminate the powder in the nozzle of the sustainer and ignite it. Attached a nice review video below. (Debunks Stine’s particle theory, which is also quoted in Robert Edmonds CiCi2 instructions.)

But what’s the purpose of the holes in the sustainer? The sustainer motor is ejected anyway, are the holes just to protect from overpressure?

Anway, I will put two in, one on each side, to balance the ejection charge. I think unbalanced ejection holes in some forward motor gliders resulted in cracked glider

 

[Rktman]

Interestingly, the CiCi2 sustainer plans are DIFFERENT from the plain single stage CiCi.

https://www.spacemodeling.org/jimz/other/edmonds_cici.pdf


You may want to look at the CiCi2 plan, as if you later decide you want to add the booster, I am not sure it will work with the CiCi single stage. However I am pretty sure the CiCi2 SUSTAINER could be flown as a SINGLE stage, except you will have to add a launch lug (the CiCi2 only has one—- on the booster, but I will also probably add one to sustainer so I can fly it single stage.)

Also on the CiCi single stage, the Person who posted the plans (God bless him or her!) also put in some HANDWRITTER dimensions that I don’t think were in the original instructions (wouldn’t be needed as everything was precut.) dimensions on the CiCi2 are TYPED in, but I think THEY were also added later (again, why put them in when everything is precut.). But the single stage CiCi and CiCi2 sustainer dimensions don’t match.

On the single stage,
the fuse is 3/16
The wing and motor mount are 1/8
The canard and rudders are 1/16

The body tube is 2 1/2”

The nose cone is balsa, described as 1 3/4” long with 1/2” shoulder

On the CiCi2, the sustainer
The fuse is 3/16
The wing is 1/8. (The motor mount is integrated as a single piece with the fuse)
The canard and rudders are 3/32

The Body tube is only 2”. (There’s a reason for the difference, you add a tape ring, I guess Mr. Edmonds ASSUMED you would use 1/2” tape)

The nose cone is described slightly differently than above, 1 1/2” long with 1/2” shoulder.

I just decided I’d go with 3/16 for the fuselages, and 1/8 for wing, canard, and rudders.

I was just planning to use repurpose a Viking plastic nose cone for the balsa, but this may unbalance the sustainer glider. Robert Edmonds had such (to my experienced well placed) confidence in his design that he didn’t recommend any preflight testing or trimming. I am thinking that plastic is going to weigh a bit more than balsa, plus I am not going with the recommended balsa thicknesses. So mine may need some trimming

I'm assuming the difference in balsa thickness between the CiCi single stage and the CiCi-2 sustainer canards and rudders is due to the increased stresses of the 2-stage version. The thinner balsa of the single stage CiCi's canard is also supported and reinforced by the offset motor pylon so he went with something thinner to save weight. I'm guessing that the canard angle is also a hair less than the 2-stager since the thinner canard balsa would mean a lighter nose.

Of course those differences don't affect your build. But what will, which you correctly pointed out, is that you'll need to trim the gliders because of the balsa and nose cone substitutions. Not that big a deal. I'm looking forward to the video of the awe-inspiring flight!

 

[Rktman]

Okay, I clearly understand the holes in the booster section, they release the cool gas in the lumen of the tube when the zero delay motor burns through, allowing the hot gas to move forward to illuminate the powder in the nozzle of the sustainer and ignite it. Attached a nice review video below. (Debunks Stine’s particle theory, which is also quoted in Robert Edmonds CiCi2 instructions.)

But what’s the purpose of the holes in the sustainer? The sustainer motor is ejected anyway, are the holes just to protect from overpressure?

Anway, I will put two in, one on each side, to balance the ejection charge. I think unbalanced ejection holes in some forward motor gliders resulted in cracked gliderView attachment 437192

Are there two holes in the booster section or just one?

Good idea to add the 2nd pressure relief hole in the sustainer. A lot of reviews of the single stage CiCi mention the ejection charge snapping the fuselage right aft of the motor pod. That's why later kits moved from an integrated pylon to an offset side-mounted pylon that's glued to the canard wing and the side of the forward fuselage.

 

[BABAR]

Balsa fillet/cheater

Eureka!

Glued on lightly, kept it off the lateral side. Then sanded bevel BEFORE attachment. Easy!

 

[BABAR]

Are there two holes in the booster section or just one?

On ALL my black powder gap stage rockets, I use at least two holes 180 degrees apart (or three 120 degrees.)

I don’t know for sure, but it doesn’t seem like a good idea to put an asymmetric force on the rocket just prior to staging.

Main thing is to put the holes immediately tail-ward of where the base of the sustainer motor will be (just below nozzle) so the hot gas can get as close to the nozzle as possible before going out the sides.

 

[BABAR]

Okay, alignment planning.

The pic is a montage of the instructions pages 1-3.
The vent holes in both the booster and sustainer are placed 1/2” back from the front end of the tube.
Okay, for the booster, this is important, as it gives you 1/2 inch to “nest” the sustainer motor into the booster tube. For those who haven’t done much black powder staging, this is MINIMUM DIAMETER staging, so basically you are using the rear 1/2 inch of booster motor itself as the “coupler” between stages.

In the plans, the nose cone shoulder is 1/2 inch long, the tube is 2 inches long.

The motor is about 2 3/4 inches long.

So AS DESIGNED, The nose cone shoulder acts as the sustainer engine block, uses up 1/2 inch of the 2 inch length of the tube, leaves 1 1/2” for motor insertion.

You stick the motor in (make sure to put it in FORWARD, nozzle end out and back!) transiently and mark the motor at the tube edge with a pencil which if you did it right should be 1.5” from the front of the motor.

This leaves the rear 1 1/4 inches of motor sticking out.

Take out the motor

You do three tape wraps around the motor, forward end of tape at your mark, to create a “ledge” at the back (also a ledge at the front, but doesn’t matter, you already have a motor block so it can’t slide any further forward anyway).

Scotch Tape width is 3/4 inch wide, so the rear end of the “ledge” is 1/2 inch from the BACK end of the motor

Voila! The motor should “nest” into the booster tube exactly in front of the vent holes (so place the FORWARD edge of the booster vent holes BEHIND the 1/2 inch line.

(Thought for re-design.....make the sustainer tube 2 3/4 inches long. Subtracting the 1/2 inch motor shoulder, this automatically leaves 1/2 inch sticking out the back. Pluses= don’t have to mess with the tape. Minuses=adds weight to forward end of sustainer, which may already be too heavy cuz I am using a probably heavier plastic nose [cuz I’m cheap])

Now, for the SUSTAINER holes.....as designed they are initially occluded either partially by the nose cone shoulder (see comments from Rocket Reviews below) or by the motor itself, i.e., AS DESIGNED the motor when fully inserted COVERS THE HOLES!

Again, not sure why they are there, except possible to reduce any overpressure from ejection charge going into essentially ZERO space as designed. The sustainer motor is NOT taped in, although instructions say you may want to LOOSELY friction fit it just enough so it doesn’t fall out on the way to the pad, but it needs to be pretty loose. Once the booster lights, all the rocket forces should be working in concert to keep the motor in place until sustainer ejection motor fires.

In my case, I think I will put the forward holes 1/4 inch from the front, punch two holes one on each lateral side 180 degrees apart. Yup, they will be occluded by the nose cone, but it is plastic, hollow, and I am using a Viking nose cone and not using the rear closure (which also reduces weight). So after putting the holes in the tube, I will stick the cone in, Mark the holes on the shoulder, pull the nose out and DRILL the holes into the shoulder sides. The nose cone shoulder will still function as a motor block 1/2 inch from the front of the tube, and the holes will be wide open even when motor is in place. Then stick nose cone back in, line up the holes, and permanently glue it in place.

?? Given this is plastic to paper, do I need epoxy, plastic glue, wood glue, or thick CA??



From RocketReviews

https://www.rocketreviews.com/edmonds-aerospace-cici--by-john-thro.htmlOne possible "gotcha": When the nose cone is installed, it looks like it's partially blocking the vent hole in the side of the motor tube. To supposedly "fix" this, I carved quite a bit of balsa from around the nose cone shoulder in order to open up the vent hole. After I did this and glued the nose cone on, I contacted Rob Edmonds by email, who told me that the vent hole is supposed to be about halfway obstructed by the nose cone shoulder. Oh well. As it turns out, this doesn't seem to make any appreciable difference either way. My sons and I have built three CiCi's, have flown two of them, and the motor ejected just fine from both of them.

 

[kuririn]

This is gonna be good.

 

[BABAR]

Are there two holes in the booster section or just one?

That's why later kits moved from an integrated pylon to an offset side-mounted pylon that's glued to the canard wing and the side of the forward fuselage.

In my case, there are as many holes as I want! I am going with two,

When I compared the CiCi single to double, I noticed the difference in engine mounts, offset separate mount on single with appropriate grain direction, INTEGRATED mount on double with INAPPROPRIATE grain direction. Since I am not interested in long duration flights, I may reinforce it on both sides with 1/32 basswood with transverse grain direction.

I’ll see how these do. If booms break, I have some carbon fiber rods that I could easily attach for reinforcement. I think since I have a bunch of raw balsa (since most of my heli and airbrake rockets are just balsa and cardstock, heck most of them don’t even HAVE body tubes or motor mounts as such) I go through a lot. Any time I went by Hobby Lobby (pre Covid) I would stop in and grab a sheet with my 40% coupon, finally I just ordered some 10 packs of

 

[BABAR]

Body tube and nose of the sustainer.....

Nothing sacred about the forwar/rear position of the holes.

Despite the attachment above from the RocketReviews report if discussion between John Thro and Rob Edmonds, I figured if the holes are for decompression, go bit or go home. And given my repurposed Estes Viking nose is already likely a bit heavy , every little bit I get off it helps.

Holes punched forward, 180 degrees apart, standard paper punch.

Nose inserted and holes marked.

Nose removed, drilled small pilot holes, then worked put to full size.

Nose glued in with epoxy. Motor with tape put in for display.

Looking down the barrel.

 

[BABAR]

Edmonds didn’t put a thrust ring in the booster. He uses tape on the outside, not only for ejection prevention/motor retention, but also to keep the motor from going forward.

The first part I am okay with. But IMO you only need 1/4” sticking out for external tape motor retention, so why put the motor any further back then you need?

The second part I was more iffy, about, so I did my routine internal ring. I have always felt commercially sold and used LPR motor blocks were overkill, much thicker and heavier than needed. I cut a piece of motor mount (in this case minimum diameter) tube, estimate a clip out of it (better to overestimate a tich than under-estimate), and as you can see it weighs just about nothing.

The red Mylar on the tail end is my tube protector. When is use external tape for motor retention, I put an underlying single wrap or partial of Mylar (if I want color, in this case why not?) or Cello tape on. When I tape the motor in before launch, the tape goes OVER this. At the end of the flight, the attachment tape comes off easily without risk of taking the outer paint layer (or in this case a piece of unpainted tube) with it.

 

[BABAR]

Wings and canards on.

Also some Mylar over the Sustainer fuselage and over the Booster Wing to prevent nozzle jet from lighting the balsa on fire.

 

[BABAR]

One thing I did NOT like in this design is the integrated fuse/motor mount. The grain direction is wrong, seems like a bad place to put a short motor tube with motor eject.

1/32” balsa ply with grain transverse to fuse reinforcement here.

 

[BABAR]

Launch lug.

Didn’t want to cooperate with my balsa fillet, but there was a rough spot here that wasn’t sanding out, so I just covered it with the lug. The rod is to make sure it us straight.

 

[Rktman]

Looking real good!

 

[BABAR]

Added lug on the sustainer (not in original CiCi2 plan) to option fly single stage.

 

[BABAR]

Added a FORWARD motor block on the booster. Again, weight is about nothing (maybe I should add the glue, but kind of hard to measure that.)

This keeps the sustainer motor from falling too far into the booster. I think it also means I don’t need to use the tape motor block in the instructions. The forward end of the block slightly covers the port holes, I will re-punch those when the glue on the ring dries.

 

[BABAR]

Checked the alignment.

The wings look like it got them pretty much perpendicular to the fuselage. So since the ends of the wings are squared as well, all I have to do is line up the vertical stabs with the edges of the wings, and the stabs should be pretty straight.

As @Rktman mentioned in an earlier post, trying to handout the parts for such perfect alignment is beyond my skills, so I tried to make up with cheaters and other methods to keep them straight. I used an index card as an angle checker

 

[BABAR]

Completed Sustainer

 

[BABAR]

Completed Booster

 

[BABAR]

Stacked for flight

 

[BABAR]

Not five minutes old! Test flight break!

That was WITH over 7 grams of tail weight to get a decent glide.

 

[Rktman]

Added a FORWARD motor block on the booster. Again, weight is about nothing (maybe I should add the glue, but kind of hard to measure that.)

This keeps the sustainer motor from falling too far into the booster. I think it also means I don’t need to use the tape motor block in the instructions. The forward end of the block slightly covers the port holes, I will re-punch those when the glue on the ring dries.

Great idea to add a forward block to eliminate having to wrap the end of the sustainer motor with tape to keep it from sliding into the booster tube. Simplifies things and shortens prep time. Going to add that tip to my copy of the instruction sheet.

 

[Rktman]

Not five minutes old! Test flight break!

That was WITH over 7 grams of tail weight to get a decent glide.View attachment 437450View attachment 437451

Haven't you heard that gliders fly better after they break and you repair them?

 

[BABAR]

12” carbon strip

 

[BABAR]

Okay, questions regarding elevation between canard and wing.

It’s hard to tell from the plans, because the submitter didn’t get the full fuselages on one sheet.

But the CiCi 1 does get the fuse on one sheet.


https://www.spacemodeling.org/jimz/other/edmonds_cici.pdf
Looks pretty clear there is angulation here.

Also on checking it out, the CiCi 1 is moderately different from sustainer on CiCi 2. Canard on bottom, canard on top, but also appear at a different incidence,

On the CiCi2, the BOOSTER looks like there is a different in incidence between canard and wing, but on both the fin scans and the instructions, looks like on the SUSTAINER the canard and wing are coplanar.

https://www.spacemodeling.org/jimz/other/edmonds_cici_2.pdf
Asking the question because I am working on a redesign, integrating a carbon fiber strip.

 

[BABAR]

@georgegassaway web site shows plans for a canard boost glider where it looks like both canard and wing are perfectly coplanar.

It’s similar to the CiCi except it has a pop pod

https://georgesrockets.com/GRP/CONTEST/BRB_contest/GliderPlan/GliderPlan.pdf
Interesting as the CiCi because it is a rocket glider as opposed to pop pod has to carry weight of a nose cone and body tube and launch lug up front. That said, the red picture from this of George’s posts

https://georgesrockets.com/GRP/CONTEST/BRB_contest/GliderPlan/Half-A_BoostGlider.html
Shows he added a bit of clay nose weight, but hardly the same as a Viking Nose Cone and a body tube and launch lug and motor mount.