29mm Big Daddy Build

I found an Estes Big Daddy kit in the cupboard, so I thought I'd build it. Except it seems sad to put a 24mm motor mount in a 3" rocket, so I upgraded it to 29mm. Here's the build, in pictures.

First, the parts that come with the kit, and the parts necessary to modify it to 29mm. (Ha. Parts. I crack myself up.)

After the "parts" photos, the first order of business was to modify the centering rings -- I used a compass and straightedge to find the center of the circle, drew two lines through it, then traced the new 29mm tube outline onto the ring. A few minutes with the hobby knife left a nice pair of 3"-->29mm rings.

Of course, I like to put big motors in things, so in case I ever put an H180W in this, I decided it might be a good idea to glass the centering rings. One layer of 6 oz. on each side sounded like enough, so that's what I used.

First, here's all the glass cut.

I prepared two caul plates (sort of) from some scrap G10 and wood pieces wrapped in saran (best cheap mold release EVER!).

Third, here's the rings glassed up and ready to be compressed, and here's the ring sandwich (mmmmm... sandwich) assembled and ready to bake.

Cook at 150 ºF for 90 minutes, or until golden brown. Trim away excess, serve immediately.

That's gonna be sweet.

I laminated the fins on mine with tissue paper and finishing resin. It's pretty much bomb proof. Last time if flew the chute lines ripped out and it tumbled to the ground with no damage.

While the rings were in the oven, I beveled the fins using 100 grit sandpaper. They came out pretty decent.

But then that H180W came into my mind again, so I opted to go ahead and glass the fins too. I found some 3.25 oz 4HS weave that seemed nice enough and would provide some stiffness, so off we go again. 90 more minutes and ding, fins are done:

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Finally, I hacked away at the root edges until they were small enough to fit the 29mm motor mount.

Indiana said:

I laminated the fins on mine with tissue paper and finishing resin. It's pretty much bomb proof. Last time if flew the chute lines ripped out and it tumbled to the ground with no damage.

Click to expand...

Great minds think alike. The other good reason for laminating the fins is: you don't have to fill any balsa grain!

While the fins were in the oven, I filled the body tube spirals with Elmer's. This included the annoying grey spiral you have to push in with your thumbnail before filling, to prevent the annoying "phantom spiral of death" from appearing in the paint job. I hate the phantom spiral of death.

I also took this opportunity to assemble the motor mount. I tacked the rings in place using CA and then filleted using 5-minute. I really wanted to build this with wood glue, but anything that was wood glue-able turned into epoxy-only-able after I glassed it. Darn!

OK, so that first "part" picture was a bit of a lie. I hate Estes rubber shock cords, so I replaced it with a Kevlar line epoxied to the motor tube to keep everything in place during descent. And finally, I glued the whole shebang into the airframe.

Coming down the home stretch, time to glue the fins in. One at a time until they're all there.

Nose cone on for a quick photo op before attaching the launch lug and priming.

One more part switch-out: I changed the 3/16" lug for a 1/4" brass one (H180W, remember), thus removing the last part I could have possibly wood glued to the airframe. Oh well.

And, time for finishing! The fiberglass weave on the fins is filled with three coats of UV Smooth Prime primer from PolyFiber. I love this stuff to death. It's way thicker than Kilz, can be sprayed or brushed on, dries fast, and sands like a dream. The sanding dust comes off in sheets, like a big white powder waterfall. This is my second can -- EVER -- and I've built a lot of (big) rockets with it!

Here's the airframe drying after the first coat of Smooth Prime on the fins. It's all sanded up and waiting for spray primer now, but it's raining off and on outside, so I can't spray anything at the moment without some serious blush going on. I'll probably do that tomorrow.

Anyways, that's it for now. I'll update with paint and decals, and then when I fly it. Do you think they'll laugh at me at Balls if I put it up there?

Dude...glass the BT. Your adding nose weight - right? Heavy nose + Estes BT + H180 = collapsed BT. I had that happen on a G64. Since you've primed it already, maybe you could put a coupler tube or something on the inside to reinforce it. I donno.

-DAllen

Nice build. I think I might use this to help me out with my 29mm Big Daddy and Fat Boy. By the way, are you going to use nomex or wadding?

daveyfire said:

Coming down the home stretch, time to glue the fins in. One at a time until they're all there.

Click to expand...

Looking good!

One thing I do with my Big Daddys now (including the 38mm one that's in the works) is to extend the fin slot to the end of the tube with my paramedic shears (those things'll make nice clean cuts through just about anything!). That way, I can put the fins on the tube, adding some heavy-duty internal fillets and then insert the whole fin can into the tube as one assembly. It would also make it easier to foam, if you're so inclined.

Ya might also think about adding some motor retention clips when you do your next B-D (darn, these things are addictive! :lol.

I built one of the original release Big Daddy kits several years ago.

The kit was designed by Matt Steele when he worked at Estes. Matt had told me that laser cut centering rings had been made which would allow the Big Daddy to fly on 29mm motors (I think Matt said there was thought at the time of making the Big Daddy an North Coast Rocketry kit and using Dark Star motors).

Matt sent me a set of these plywood rings and I built my Big Daddy incorporating these parts.

I have flown my Big Daddy twice. Once, at NARAM-42 with an AeroTech F25-9W motor and at NARAM-50 with an F27-7R. Both flights were great!

also, don't forget to use another method to attach the cone to the shock cord. dont trust the "as delivered" hook, its awfully brittle

Stewart32 said:

also, don't forget to use another method to attach the cone to the shock cord. dont trust the "as delivered" hook, its awfully brittle

Click to expand...

True dat!

Man, that's very cool!

I love the "Ding! Fins are done!" comment...

My 1st BD. It had four-24mm tubes and foam core baord centering rings.

I put in too much nose weight. Here are the results of the first and only flight.
Penultimate Lawn Dart. Note one of two D12-5's protruding from the rear which ejected just after impact. Should have used the 3 seccond delay. Nothing was salvageable, even the hollow cone was crushed.

The second BD flew very well on an AT F22J. Slow lift off with thick black smoke. Changes made: Basswood fins, ply-wood CR's w 29mm MMT, foamed the fin can. 1 oz weight added in the cone. Still need to foam that and add a better anchor.

Have #3 in the bag and will probably revisit the four-24mm MMT.

Good Luck with yours at BALLS. Do post pics of the flight!

Thanks for the replies and comments, everyone!

It stopped raining so I got a chance to put on some paint today. I'm not going with the "grey" (which looks more like blue on the packaging to me, but maybe I'm color blind?) blended to red -- I'm just going with red, with a black nose tip. With the yellow decals it should be the right color scheme

dallen: I'm not planning on glassing the BT at this point. Quick thought experiment, to see if I should have:

Sum of forces on the nose cone during flight = dynamic pressure*frontal area + mass of cone*acceleration. Assuming maximum acceleration and maximum velocity (--> Qmax, roughly) happen at the same time gives a good "worst case scenario" approximation. Pre-paint the rocket weighs about 8 oz. Let's also assume 2 oz nose weight (though I'm not sure even that is necessary, due to base drag... further investigaion pending...). RockSim says max velocity of 1041 ft/sec and max acceleration of 58 gees on an H180W. The stock nose cone weighs 1.64 oz, plus 2 oz noseweight makes a 3.64 oz cone, which "weighs" ~13 lbf at maximum acceleration. I hate FPS units for dynamic pressure, so let's switch over to metric for fun. 1041 ft/sec = 317.3 m/sec, and the density of air at 25 ºC (desert?) is ~1.2 kg-m^-3, so then assuming a worst-case drag coefficient of 1, Qmax is 0.5*1.2*317.3^2, or 60.408 kPa. A 3" nose cone has area 0.004560 m^2, so then the maximum force due to dynamic pressure is 275.46 N, or 61.93 lbf. Total sum of "crushing" forces on the nose cone (and thus body tube) during flight is then 61.93 + 13 = ~75 lbf. (Side note: even with a crazy 6 oz of noseweight, aerodynamic forces still make up almost 70 percent of the crush force on the airframe!)

Time to break out the bathroom scale. I put a piece of 3" airframe underneath the rocket to keep me from breaking off the fins. Push hard and... the tube held up to a sustained 72.5 ± 0.5 lbf with no sign of weakness... close enough considering the assumptions in my calculations.

Moral of the story: I hope I'm OK without glass. This is mostly supposed to be a "mid-power" rocket anyways, and the H180W is my worst case scenario, fitting well with the theme of this post...

jj: I think I'll use wadding for now. Or maybe Nomex. I usually don't decide until I'm prepping the rocket on the field! (It usually depends on what I find fastest in the truck, the box with the Nomex shields or the bags of wadding. Wadding usually wins.)

n5wd: I normally do that on most of my high power airframes, but I wanted to keep this light (hah! failed that one!) and make the build as simple as possible, so I elected to not extend the slots to the end on this one. I put gobs of 5-minute on the roots when I first slid them through the slots, so I hope that made some sort of fillet. They seem to be in there pretty strong, and they're extremely stiff with the glass, so I don't think they'll detach in flight. Oh, and on the motor retainers -- you read my mind! (Forgot to mention the t-nuts in the narrative)

Initiator: this kit really seemed like a NCR design when it first came out, especially with the larger 3" airframe that Estes hadn't ever featured prior to the acquisition. It almost looks like a smaller version of the Big Brute. Glad you've had success with your upgrade!

Stewart: For sure. I think I might have to cut the base of the nose cone off anyways, to make room for the motor...! The 4x24 configuration is very cool, but it would be very tough to get it stable in such a short rocket -- you lose the base drag advantage with all those plumes out the aft end, plus four D motors gets mighty heavy might quick. Hopefully I'll make it to a launch before Balls so I can focus on my primary projects at Black Rock, but it's my backup launch plan.

Loopy: yeah, I'd expect that from you I had the song stuck in my head again today as I was sanding the fins and prepping them for paint...

It sounds like the Big Daddy is a favorite for kitbashes and mods. I'm happy to join the tradition!









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