29mm Big Daddy

[DM1975]

What a great looking stubby rocket, I first saw this in Hobby Lobby and it just screamed 29mm conversion. I figured it would be fun to do and provide a nice looking rocket as well.

I used a bit of epoxy to do the fillets on the fins and to coat the bottom centering ring and attach the retention hardware but mostly stayed with wood glue. I also ran the motor tube all the way up to the nose cone base to help keep the wadding needed for it down to a minimum and used a steel leader to attach the shock cord with. I also beefed up the bottom centering ring with a piece of balsa.

In the photo showing the fin can area the motor tube has part of a 29 to 24mm adapter in it to keep the tube from distorting while I was fitting the fins.

 

[DM1975]

One thing I completely forgot about was to harden the balsa fins untill after I primed the whole thing so I went back and sanded everything down and used wood glue and card stock to cover the fins.

It took a lot of sanding and several coats of primer to finally get the area smooth where I added the card stock but it finally came out decent.

 

[DM1975]

I decided to do a couple of layers of flames on this rocket so I painted it flat black to begin with and then painted ghost flames on it with metallic midnight black.

After that I painted metallic silver, metallic blue flames over that and clear coated it all. Painting is my favorite part of building rockets and their was not a lot of real construction to be done on building this rocket so it was most all fun.

I am sure the fins will hold up as I have them now, but I am going to work my way up with the motors to be on the safe side. I will report on it after it flies. Hope you all enjoy.

 

[MarkH]

Very nice. What do you plan on flying it on? Big Daddy on a G would be cool.

 

[Pantherjon]

Very nice!

A G76G will give it a good ride!

 

[Davidtmp]

Nice paint job. I am thinking of doing this bash with my BD as well. Thanks for sharing.

 

[DM1975]

Thanks guys, I am going to launch it first on a smaller motor for a test flight, but this thing just screams mojave green

 

[TheRocketNerd]

Great Paint job! I built a 29mm big daddy but I built mine to take big 29mm loads. I used ply rings and fins and added necessary nose weight. I haven't flown it yet; I still have to do some OCD-knit picky finishing. I'm thinking I'll paint it like the original big daddy.

Let us know how it goes!

 

[DM1975]

Thanks, I don't plan on using anything bigger than hobby line motors in it. I hope it holds up well to it. I figured the balsa reenforced centering ring and card stocked fins would be strong enough for that, but not really anything bigger.

 

[KHamel]

Very Nice! Flames look great!

 

[Handeman]

Thanks, I don't plan on using anything bigger than hobby line motors in it. I hope it holds up well to it. I figured the balsa reenforced centering ring and card stocked fins would be strong enough for that, but not really anything bigger.

I have found that the up part isn't what you have to worry about, it's the landings. If the fins are strong enough to handle the landings, they should be plenty strong enough to handle the motors.

 

[Davidtmp]

what are you using for motor retention? I see you are using the T-nuts. I tried to find the clips, but the only way I could find any was in a "kit' to hang 10 mirrors or pictures. I looked at storm door clips, but they are too long for a BT-80 sized rocket. Are you just using washers??

 

[MarkH]

what are you using for motor retention? I see you are using the T-nuts. I tried to find the clips, but the only way I could find any was in a "kit' to hang 10 mirrors or pictures. I looked at storm door clips, but they are too long for a BT-80 sized rocket. Are you just using washers??

I found some .032 " thick by 1/4" wide brass at my local hobby shop. Drill a hole for the screw and bend the the strip to flit the motor mount and aft closure. This is the method that Mr. Kaplow describes in a post on YORF, but I can't seem to find it. I think it was a .pdf posted about the NCR Phantom 4000.

 

[DM1975]

what are you using for motor retention? I see you are using the T-nuts. I tried to find the clips, but the only way I could find any was in a "kit' to hang 10 mirrors or pictures. I looked at storm door clips, but they are too long for a BT-80 sized rocket. Are you just using washers??

I make my own out of clothes hanger wire. So far they have worked really well.

 

[Davidtmp]

I make my own out of clothes hanger wire. So far they have worked really well.

Hmmm, I may try that out as well. Makes sense, I tend to complicate things too much!! I'm just playing around with smaller models to see what works best for me, so when I move on up to mid power I have some sort of idea of what I want to do.
Thanks guys.

 

[ttabbal]

I did one of these a couple years back. It's fun as hell to fly. I used 1/8" ply for fins and rings and added noseweight, probably more than needed, to balance it out. I've flown on G reloads for the 29/40-120 case without any issue. Packing the chute is a little tight, I use a 18" nylon chute with 1/4" kevlar shockcord. I also modded the nosecone to add a plywood bulkhead and u-bolt for attachment as the nose is now somewhat heavy and I didn't want it breaking loose from the chute as it could cause injury if it hit someone.

G53FJ-7
G71R-10
G76G-10

Those are my favorite loads to fly it on. I've done a couple dozen flights and it comes back every time. It got a little damage on one fin on the salt flats, but it was more cosmetic than anything else. For motor retention I used a 29mm Slimline. I'm a little weird about motor retention.

I've actually considered building one with a 38mm mount for larger G and low H loads. It's great fun to mod this kit. I need to buy another one.. I think Hobby Lobby has a 40% coupon this week.

 

[falingtrea]

what are you using for motor retention? I see you are using the T-nuts. I tried to find the clips, but the only way I could find any was in a "kit' to hang 10 mirrors or pictures. I looked at storm door clips, but they are too long for a BT-80 sized rocket. Are you just using washers??

I have used conduit reducing washers. Made of galvanized steel, usually the 1 1/4 to 3/4 size works for 29mm. Just drill holes for the screws. The raised flanges fit well on the case.

 

[DAllen]

Several lessons I learned on the 29mm Big Daddy:

1. It needs a lot of nose weight to be stable with G motors.

2. An unreinforced body tube will collapse under thrust from a full G motor because of the heavy nose cone.

3. Rail buttons are your friend.

I noticed that you did not glass anything on this rocket. My personal recommendation is not to fly that much more than a full F otherwise you may discover the speed of balsa and whether or not you have a stable rocket.

-Dave

 

[DM1975]

Thanks for the info. If I fly it on anything over an F I will make sure it is in an isolated area with no one around. Do you think that even with the card stock glued around the fins that the balsa will fail?

 

[DAllen]

I think mid F motors like the Econojet F20, 24mm RMS F24 and F39 I would think are not a problem for how you built it. Maybe you covered this already and I missed it but you will definitely need to adjust the CG by adding nose weight on a G motor. I do not recall how much I had to add for mine. There are a few articles on the same type of build:

https://www.rocketreviews.com/cgi-bin/search/searchall.cgi?big+daddy+29mm

Attached is the Rocksim file I made for my bird. My body tube collapsed (or something really bad happened) when I placed a G71 in it and I lost it forever as it dissappeared into jet-black soil with its jet black paint job.

IMHO, if you want to shove a G in it I would try a G with a lower burn rate like a G40 and make absolutely sure you CP/CG is good.

-Dave

View attachment big daddy - 29mm.rkt

 

[WillMarchant]

Hi Dave:
Thanks for posting the RockSim file. You might want to go over to https://www.apogeerockets.com/education/newsletter_archive.asp and grab the couple of issues that talk about "short, fat rockets and RockSim" as you can get some "bonus CP" help.
Best wishes,
Will

 

[DAllen]

You know...now that Will posted that link I remember someone telling me about that AFTER I built my 29mm BD. I recall thinking, "Maybe I didn't need that much weight after all." That's a good read before flying your BD and it's still good practice to make absolutely sure you CP/CG is good when making mods like this.

-Dave

 

[DM1975]

Thanks for the information. I simmed it out before construction to needing 3 oz of nose weight but I am going to weigh it and do a mass override to get it exact. I will keep in mind all of this information as I finish out the sims and finalize the build. I sure appreciate all of the info.

 

[DM1975]

I have a question for you guys about the issue with the body crumbling. My motor tube goes all the way up to the base of my nose cone, will this be enough to help keep it structurally sound or should I glue a coupler inside the body tube to help?

 

[TheAviator]

I have a question for you guys about the issue with the body crumbling. My motor tube goes all the way up to the base of my nose cone, will this be enough to help keep it structurally sound or should I glue a coupler inside the body tube to help?

The motor tube will supply support to the airframe only near or between the centering rings. The length of the motor tube forward of the centering rings means almost nothing to structural integrity.

 

[DM1975]

Roger, I will add a coupler inside the body then and re weigh it all.

 

[ttabbal]

Several lessons I learned on the 29mm Big Daddy:

1. It needs a lot of nose weight to be stable with G motors.

2. An unreinforced body tube will collapse under thrust from a full G motor because of the heavy nose cone.

3. Rail buttons are your friend.

#2 Really? I haven't had any problems. I have about 8oz of noseweight. My body tube is still perfect. I did use 1/8" ply fins and rings, so there will be some extra support there. Not enough to make up for the effect you are talking about though. :confused2: I think I did soak the tube end in super glue, but I wouldn't expect a big difference from that.

Totally agree on #1 and #3 though.

 

[DAllen]

Yes. Of course I don't have the dismembered body to prove it but only my recollection of the flight. I distinctly recall seeing the NC go crooked under thrust and the rocket flying erratically and disappearing into the ether. :bangpan:

-Dave

 

[DM1975]

I am working on the rail buttons now. I just got my first launch rail and will be switching everything over to rail buttons soon. As for the nose weight, I will probably reencorce the inside with a coupler. And for the balsa fins, I do believe they will hold up. The RDR-1 has balsa fins and can fly on G's so hopefully with that and the reenforcing I did it will hold together.

So far on the nose weight the rocket sims out as only needing 3oz. of weight, but after I get my 29mm casing in and get a reload on it I will actually physically re-weigh it and check the CG to make sure that is all that is needed. This weekend, with any luck, I will fly it on at least a D12-3 or maybe an F reload.