Estes #7266 Red Nova Build

[EXPjawa]

This is a pretty straight up kit to build, but I'll do a thread for it anyway as it is still a neat looking rocket that ought to prove to be popular. Some background - the Estes Red Nova was just introduced last month, at the end of 2017. This is a low power kit, with typical light weight paper tubing, and is labeled as a skill-level 2. The extra set of fins and 24mm motor mount probably account for that. Just the same, this should be a fun build. I also think that this design has potential for modification, more on that later.

Entry #1: Unpacking

The package as purchased:

And opened up:

The kit contents are pretty straight forward; there's a standard 18" segment of BT-60, a 3" BT50 for the motor tube, molded nose cone, a sheet of laser cut 3/32" balsa of the usual quality from Estes, plus a small parts pack (1/4" shock rubber cord, a block of nose weight clay, 3/16" lug, centering rings, motor block and hook) and decal sheet. I'm not sure if the nose cone is a new design, but I've not seen it before. It is an interesting design - a ramjet style, but straight conical (others I've seen were ogive), with a 1" long straight lead section above the shoulder. The "inlet" cone is only slightly smaller than the inlet diameter, so the step in profile is less than that of the old cone used on the BSG Laser Torpedo or Teros models.

The next step is to measure the parts to build a Rocksim file that's reasonable.

 

[solid_fuel]

I have been waiting for a build thread for this rocket. op:

 

[kuririn]

I think the nose cone might be the same as an obscure OOP X prize kit, the Thunderstar (minus the tower). I know John Boren has said that they like to use up parts that they have an excess of in inventory with their new designs. The design reminds me of the Teros missile, with an extra set of fins. Mod to two stage?

 

[solid_fuel]

I see your builds progress similar to mine :tongue:

 

[SCIGS30]

I just bought this kit at the local hobby store, I really like it. I am finishing my New Estes Patriot right now, but maybe I will start this kit next week.

 

[EXPjawa]

I was working on it tonight, actually. Will have to update in the morning.

 

[EXPjawa]

OK, so, an update. My first act was to measure the parts and build a reasonably accurate Rocksim file.

If its to be believed (or I didn't screw up something), it appears that Estes erred on the side of caution stability-wise. The sim suggests that the model has a decent stability factor even without the 1/2 oz of clay ballast included, though it is in place in the model above. I also experimented with some variations, but I won't get into that at this time.

Next, I took another look at the parts and noticed it also included a 1/8" wood strip, which is to be used to make mock conduits on the sides. That's a nice, simple detail that I didn't notice originally. I also opened up the small bag of bits for a better pic:

On to the actual construction. The first step is the motor mount, though the first thing I did was remove all 8 fins and sand them. After evening them up, I rounded the leading edges. I'm not going to bother with airfoiling them on a model such as this. I will note, though, that the balsa is the usual firmer density stock that we've come to expect from Estes. It should hold up pretty well without papering.

Then, on the motor mount. This is pretty standard stuff, no need for detail here, except to say that the centering rings were very tight on the motor tube. I had to sand the ID some just to get them on without distorting the tube in frustration. This is also the first time in quite a while that I built something with cardstock rings, so I may have forgotten how they are.

I then marked the tube. Because the cut-out marking guide included the conduit placement, I used that instead of the usual fixtures. The kit came with two instruction sets, the second being foreign language only. I used that one to cut up.

The unmarked parallel lines are for the conduit. Speaking of which, Estes included an 18" piece of stock for the purpose. The instructions call for cutting two 5.5" long pieces. That leaves the modeler with a 7" piece to do with as you will. I found that it was a suitable size for clearing out the square launch lug on the New Way Squareros that I was also building. These will be sanded in several ways before being attached to the sides of the rocket.

More later.

 

[JumpJet]

Once you actually build the model and paint it I believe your CG is gong to move back some, so your Margin of Stability is going to be less. With that said the model is still over stable based on the numbers. I have been asked to have a 1.5 Margin of Stability. So lets say without clay it's at 1.3, add clay and your now over 1.5. Plus you just know someone is going to leave out the thrust ring and engine hook out and fly it on an E9 or E12 motor so it's always nice to be a little over stable for these folks.


John Boren

 

[solid_fuel]

Can you share the rock sim file with open rocket?

 

[EXPjawa]

Can you share the rock sim file with open rocket?

Both Rocksim and OR files are attached.


View attachment Red Nova 7266.rkt View attachment Red Nova 7266.ork

 

[solid_fuel]

Cool. Thanks.

 

[Sooner Boomer]

Also, thanks. I was going to ask for this.

 

[EXPjawa]

OK, so, after marking the tube for the various fins, conduits and lugs, I then scuffed the glassine layer in those areas, then remarked with a pencil:

Before I started attaching fins, though, I test fit the motor mount and found that like the centering rings ran small. Whereas I had to sand the ID of the rings to fit on the motor tube, this time the rings were undersized for the body tube. I didn't measure precisely, but they could chuck around inside the tube visibly. I found that if I wrapped a strip of masking tape around the outside of the ring, the fit was pretty close. So, what I did was this: I cut 2 strips of paper (from the same instruction set that the tube marking guide was cut out of), about 3/16" wide, the length of the ring circumference. I then saturated the strips with wood glue, like one might when papering balsa. The strips were then wrapped around the outside of the rings, with the extra width folded over and squished to the ring faces. The result looked like this:

While it isn't the prettiest thing in the world, the result is a laminated paper layer around the edge of the paper ring that is quite sound, structurally. This added enough to the diameter to get a good fit to the tube. It also has the benefit of acting as a "pre-glue" for installing the mount, like doing a double-glue joint for a fin, since the paper laminate is saturated with the glue.

With that done, I went about attaching fins. The instructions have a cut-out fin guide, but I used my trusty guillotine jig. I inserted the motor mount partly as a way to keep the tube round while the fin sets up.

One other area of note for now: the nose cone prep. The cone has a molding parting line typical of a plastic cone. However, it is a raised line that needs trimming or sanding for only about 3/4 of the length. The forward portion of the parting line is actually recessed (suggesting maybe the mold had been repaired?) and needs filling:

 

[EXPjawa]

Four down, four to go:

So, without further delay, I started on the front fins. In this case, I used the jig a little differently - as a simple stand so that I could eyeball alignment of the fins to the rear. Even with using the jig, the fins aren't exactly perfect, so now its more important to make sure that they align fore and aft then they be exactly normal to the tube...

 

[solid_fuel]

Looking good so far. Is there a reason you didn't do both the fore and aft fins at the same time? Also why eyeball the fore fins instead of using the jig?

 

[EXPjawa]

Don't misunderstand, I'm not just sticking the fins on there and saying "that looks good enough". By aligning the fins to the tube markings and sighting down the length of the rocket, I can visually verify that the fore and aft fins are coplanar. Frankly, as nice as the fin jig is, it doesn't produce guaranteed perfect results; there's still room for error that's subject to the user. So, at this point, even though the aft fins look pretty good, they aren't perfect (even if you don't notice). So, if I use the jig for the fore fins, they might be similarly off, but in the opposite way. I guess I'm saying that within the margin of error that the jig produces, the fins can be visually different if you look straight down the length even if it is very minor. So I'd rather have them coplanar and equally off front to rear, which will overall be harder to spot the error. Aside from that, the forward fins are small enough that jig I have doesn't engage very much of them, just the tip. So it is harder to use on them.

The reason I did not do the front and rear at the same time is simple: the jig is made to do one fin at a time. The vee-notch that centers the fin to the tube is only in one spot. Also, if I did them both at the same time, the aft fins would be outside the box (the jig structure) and the fore fins inside the box. The fins won't pass through the body tube opening in the box, so doing that would mean the rocket would be stuck in the jig and not removable without cutting it apart...

Anyway, I'm 7-down, 1 to go at this point.

 

[solid_fuel]

The fins won't pass through the body tube opening in the box, so doing that would mean the rocket would be stuck in the jig and not removable without cutting it apart...

I never thought about that, that would be a bummer, dude

 

[EXPjawa]

It would indeed...

The last fin is now on:

The next bit are the lugs and conduits. The lugs are self explanitory and I'll do them later. The conduits are cut out of the included strip, as shown before. They are then to be sanded, so they are bullnosed on the ends and rounded along their length. I have done one so far. You can see the before/after:

Thus concludes my update for today...

 

[Scott_650]

Enjoying watching this build - I’m basically using your build - and OR file - to rebuild my modified Estes Rookie. Probably spent as much on bits, pieces, and paint as the pair cost from the Estes Specials webpage :blush:

 

[EXPjawa]

I managed to make a bit of progress over the weekend, despite being a bit lazy. With the fins, lugs and conduits all on, the next step was to install the motor mount. As previously noted, I had to wrap the centering rings with paper to get an acceptable fit. I do worry that if an inexperienced builder put this together as manufactured, they'd only achieve a partial bond or would be relying on the glue bridging the gap between the rings and body tube. Anyway, the one modification I made in this build is in relation to the recovery harness. I'm sure this is a pretty common thing among rocketeers, though:

Once the mount was dried, I drilled a hole in the upper centering ring to pass a length of kevlar line through, and tied a loop around the motor tube. This was then drawn up and submerged under a bead of glue (on the underside of the centering ring). Once that was ready, I installed the motor mount into the tube. I used the extra scrap segment of square stock from the conduits to apply glue in a ring up in the body, then again for the lower ring once the mount was partially installed. The motor tube aligns with the end of the body tube, leaving the motor hook to stick out a bit. This means, of course, that the rocket will no longer stand on its own.

The next step in the construction is to squish the 1/2 oz of clay into the nosecone. The sim file shows that it really isn't necessary, but I default to John's wisdom and used it anyway just to be safe.

I tamped it in with a pen - you want to make sure that you get it stuck well and compacted. You can see how much of the cone is needed for the clay; its just a little beyond the inlet cone portion (shown for accurate placement in the sim file).

So, with that, the primary construction is complete. Now, it comes down to fillets and filler.

Wood glue for all fin roots, as well as along the conduits. I did the later just to make sure there were no visible gaps along the edges. And I make small wood filler fillets along the launch lugs, because it gives them a more integrated look. For the same reason, I also beveled the ends of both lugs with a sharp (fresh blade) hobby knife. I've done this (retroactively even) to most of my rockets now, since I think the beveled ends looks a lot better. It also makes it slightly easier to get on a launch rod.

So, here is how the rocket stands now (with the help of a sanding block):

The next step is to fill the grain of the fins to prep for priming. I'm not sure that I'll bother with filling the spirals, as they are pretty tightly wrapped to begin with, and, frankly, having perfectly filled spirals doesn't matter that much to me. Anyway, that's enough for now.

 

[Trident]

I’m looking forward to seeing your Red Nova completed.

I was hoping I’d have my Red Nova done, and flying before anyone. I attended Chili Blaster in Pueblo, Colorado in September and was a lucky winner of this kit from Estes. John Boren had several of them, and some Super Big Berthas given out, amongst other items. But I never got past the primer stage before cold weather set in. (And just how are your priming in Rochester?!)

Looking forward to finishing. It a neat kit.

 

[neil_w]

(And just how are your priming in Rochester?!).

Now *that* is a good question. I suspect foul play.

We're onto you, Rick.

 

[solid_fuel]

Lookin' good. What is your final color scheme going to be?

 

[EXPjawa]

I’m looking forward to seeing your Red Nova completed.But I never got past the primer stage before cold weather set in. (And just how are your priming in Rochester?!)

Looking forward to finishing. It a neat kit.

Now *that* is a good question. I suspect foul play.

We're onto you, Rick.

Getting it prepped for priming doesn't mean that I'll actually paint right away.

Lookin' good. What is your final color scheme going to be?

I don't know yet, but it will probably be a variation of the original scheme. I rather like it.

 

[Sooner Boomer]

Once the mount was dried, I drilled a hole in the upper centering ring to pass a length of kevlar line through, and tied a loop around the motor tube. This was then drawn up and submerged under a bead of glue (on the underside of the centering ring). Once that was ready, I installed the motor mount into the tube. I used the extra scrap segment of square stock from the conduits to apply glue in a ring up in the body, then again for the lower ring once the mount was partially installed. The motor tube aligns with the end of the body tube, leaving the motor hook to stick out a bit. This means, of course, that the rocket will no longer stand on its own.

And, of course, this will be the first part of the rocket to hit the ground. I've used this deliberately (the long "tabbed" engine hook) as a "cushion" when we used to fly on a paved parking lot. It's fairly easy to bend it back out after a hard landing. Easier than repairing the aft end of the body tube or dinged fins.

 

[EXPjawa]

Recent progress - the fins have all had filler applied to smooth them out. I also hardened the edges with thin CA. Next is to sand the fill smooth so that it is ready for prime.

 

[neil_w]

I admire your fortitude for applying CWF after the rocket is assembled. Even though CWF sands easily, I still find it to be a pain, if for no other reason than the ultra-fine dust it creates. Would be a double pain doing it on an assembled rocket.

Although it is simple I really like the look of this rocket. Really great design by Jumpjet.

 

[solid_fuel]

Although it is simple I really like the look of this rocket. Really great design by Jumpjet.

i really enjoy the design as well. The unique nosecone is an added bonus.

 

[EXPjawa]

I admire your fortitude for applying CWF after the rocket is assembled. Even though CWF sands easily, I still find it to be a pain, if for no other reason than the ultra-fine dust it creates. Would be a double pain doing it on an assembled rocket.

Actually, I find it easier to do with the fins attached. I've done it both ways, but things are easier to hold onto to sand when the fins are glued to the rocket body.

 

[solid_fuel]

I usually do the first coat of CWF while the fins are still attached to the sheet