RocDoc's New Build Thread -- The 24" Diameter Super Big Daddy

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rocdoc

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Well, it's that time of the year again. I am getting started on my next project. This build thread comes with my typical disclaimer: The thread will be very photo intensive. I prefer using high resolution photos hosted at another site over the thumbnails. So I apologize in advance if it takes a while to download all the shots.

I have posted a couple other build threads in case you are interested in seeing some of my previous efforts:

The Avenger 5.5 (my first scratch build): https://www.rocketryforum.com/showthread.php?t=10975

The Velociraptor Rex (my L3 certification rocket): https://www.rocketryforum.com/showthread.php?t=16491&highlight=velociraptor

The Avenger was flown two years ago at Fire In The Sky (FITS) over Memorial Day Weekend. The Velociraptor Rex was flown at last year's FITS and again at BALLS last September. I plan to fly the Super Big Daddy twice at this year's FITS. The first flight will be on a single M-impulse motor (probably CTI's M3400WT). This flight will be low and slow and close enough to the crowd that those who normally only see M-flights from the "away cell" nearly a mile from them will be able to see and hear a nearly full size M-motor.

The second flight will be from the away cell with a central N5800 C-star surrounded by four L-impulse air-started motors. This will be my first attempt at air-starts and should be a fun challenge. If all goes well, I may break my normal rule of only flying rockets twice before retiring them and take it down to BALLS to fly on an N and four Ms.

For this build, I will be using 24" diameter concrete forms (Sonotube). The outside diameter of these is actually 24.5 inches. That makes this slightly more than an 8x upscale of the original Estes Big Daddy. The nosecone will be fiberglassed foam. The nosecone itself will be just over six feet tall (not including the shoulder)! I'll be fiberglassing the Sonotube as well. The fins will be fiberglassed plywood. I was hoping to make my first attempt at foam-core fins, but I can't find high density (40-60psi) foam sheets in the right size (1" thick is only available in two foot width and 2" is too thick). Also, the swept fin design guarantees that this thing will land on a fin, so I want to have fins capable of withstanding the impact.

Here are a couple of EARLY RockSim shots showing the basic design. I haven't tried to guess at the weights of materials, so I'm not worried about the stability at this point. Once things are further along, I'll be able to get a better idea as to mass and the center of gravity.

Here is the side shot:
Super-Big-Daddy-revised-XL.jpg


And here is a shot from the aft end. The outboard motors are arranged so they can be secured against the fin tabs. This will help lock in the fins and the motor tubes. The central motor tube is 98mm and the outboards are 75mm.
Super-Big-Daddy-Base-View-XL.jpg


As always, your comments are welcome. I present these build threads as one way to tackle a build. I certainly don't believe that all my methods are the best for everyone. Feel free to chime in.

Regards,
Bryan
 
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Wow! This think is massive! This makes me want to take the trip from MA to WA, to bad school and work will have a way of interfering with that. Good luck with the project, also, is there any internal structure to give strength to such an open internal volume? Stringers, ribs, etc...
 
No, I don't think I'll do anything in the way of internal support. There is only a small section that is single-wall (just aft of the nosecone). The fincan should hold together fine with the four centering rings and the through-the-wall fins tying everything together back there.

If this were a taller rocket, I would definitely consider putting in an internal structure, but I think this short fat thing should be fine with the fiberglass-reinforced Sonotube.

Thanks for the input!
 
So I picked up a 12 foot section of the 24" diameter Sonotube from White Cap, a building supplier in nearby Tacoma. I couldn't get anything bigger than 12" diameter from Lowe's or Home Depot, even on special order. White Cap also carries 36 and 48" diameter tubes, so I think I'll have to keep them in mind for next year's project too! :y:

I've never built a rocket out of Sonotube before. The section I got was a little beat up on both ends, with some of the cardboard delaminating a bit. I took care of this with a little CA glue and some clamps.

I then used my brand-spanking new Festool Rotex sander and some 50 grit sandpaper and sanded the entire tube down to remove the label and the water-resistant outside layer. The attached dust collector really came in handy!

For this build, I will need two body tube sections (one 43" and the other 39") and one coupler section. I've decided to attach the nosecone permanently to the forward body tube section. This will make for a smoother transition at the nosecone/body junction and will allow me to make the fincan zipperless.

I will be reinforcing both the body tubes and the coupler section with fiberglass. I didn't want to try to tackle fiberglassing the entire 12 foot section at once, so I cut the tube into three sections, each about four feet in length. I will fiberglass each section individually.

In order to make it easier to apply the fiberglass, I built a fiberglassing station out of 2x4s. A 1" pipe is used to rotate the body tube. A parallel support holds the fiberglass, allowing it to be easily transferred to the body tube.

Here is a shot of the first section of tubing on the stand. The tape on both ends of the tube is two rows of bagging mastic as I plan on using a vacuum pump to get a good epoxy-cloth ratio. My old Estes Big Daddy is placed on top of the tube for scale:p Also seen on the left side of the photo is my vacuum press. I detailed this in my Velociraptor build. It is a nice little piece of equipment that makes vacuum bagging easier and more effective.
DSC7463-XL.jpg


This shot shows the 24" centering rings I cut to center the tube on the stand. These are made of scrap 3/4" plywood and will not be part of the final rocket. The premeasured 5.6 oz fiberglass is on the parallel support ready to be placed on the tube.
DSC7469-XL.jpg


After marking a straight line on the tube for a reference point, I started to wet the tube out with West Systems epoxy resin with 206 (slow) hardener. The tube absorbs a large amount of resin. I applied it with a foam roller so the entire tube was wet out.
DSC7472-XL.jpg


Here I have started the fiberglass cloth on the wet out body tube, using my reference line to start it out straight. I use a cheap chip brush to pull the fabric taught and embed it into the epoxy better. The stiff, short bristles and cheap price make this tool a very effective way of getting the fiberglass to lay down where I want it.
DSC7474-XL.jpg


I applied two layers of the fiberglass to the tube, overlapping the end slightly. Here, most of the fiberglass is off the feed roll and I continue to work it into the epoxy.
DSC7475-XL.jpg


Here the two layers of 5.6 oz glass have been applied. I had to go back to take care of a couple of dry spots, but the fiberglass laid down nicely.
DSC7476-XL.jpg


This photo shows the laying down of the 2.1 oz sanding veil layer. Only one layer of this is applied. It is only 36" wide, so I had to lay it down in two sections. This thin material will lay down nicely enough that the seam shouldn't be noticeable. I'll have plenty of sanding and filling to do later, though.
DSC7478-XL.jpg


The veil layer is complete.
DSC7479-XL.jpg


A layer of peel ply is then added.
DSC7480-XL.jpg


After wrapping the entire mess in a few layers of breather material, I applied bagging material over the tube, securing it to the layers of mastic on each end of the tube. This allowed me to vacuum bag the tube without worrying about crushing it, which is what would have happened if I would have just bagged the whole tube.:shock: I used two vacuum ports to try to more evenly vacuum out the air. Here, the vacuum press has started to pull down the bagging material.
DSC7481-XL.jpg


I'll leave it under vacuum overnight in the relatively cold garage, then move it into the house to cure the rest of the way. The 206 hardener takes forever to cure in the cold, but I didn't want to make She Who Must Be Obeyed upset by having the vacuum pump going on and off in the house all night long. :kill:
 
Holy Mother of........ WOW..

I have been thinking of re-scaling a Big Daddy to 8" airframe with those Sono Tubes, but, you just beat my wildest dreams...

Where is this gonna fly??
 
WOW!! the last time i saw a rocket -tube that big....John Glenn was inside it!
 
Any more progress on this build?

Hehe. Didn't get much response from the original posts, so I decided not to do much of a build thread. Was a little surprised to see it get resurrected after the thread fell off the first couple of pages. If there is interest, I can certainly pick up the build thread from here.

Progress has been slow. I've come to realize that one of the reasons that bigger projects are done as teams is because they take a ton of time and way more material than you expect.

The fins are nearly complete. They were an epic battle, but turned out reasonably well. I will post details and some pics later.

The two airframe sections and the section for the coupler tube have all been glassed. Shocking how much epoxy and fiberglass it takes to cover these things. Never figured I'd be buying West Systems epoxy by the 4.35 gallon drum:shock:.

I'll take some photos and get something posted this weekend. Thanks for your interest.

Bryan
 
Holy Mother of........ WOW..

I have been thinking of re-scaling a Big Daddy to 8" airframe with those Sono Tubes, but, you just beat my wildest dreams...

Where is this gonna fly??

I plan to fly it at Fire in the Sky, the largest annual launch in the Northwest, sponsored by Washington Aerospace (based out of the Seattle area). It takes place in Mansfield, WA over Memorial Day Weekend. I just Googled it. Turns out it's only six hours from Oregon City to Mansfield:wink:. Come fly with us and say hi!

Bryan
 
Hehe. Didn't get much response from the original posts, so I decided not to do much of a build thread. Was a little surprised to see it get resurrected after the thread fell off the first couple of pages. If there is interest, I can certainly pick up the build thread from here.

Progress has been slow. I've come to realize that one of the reasons that bigger projects are done as teams is because they take a ton of time and way more material than you expect.

The fins are nearly complete. They were an epic battle, but turned out reasonably well. I will post details and some pics later.

The two airframe sections and the section for the coupler tube have all been glassed. Shocking how much epoxy and fiberglass it takes to cover these things. Never figured I'd be buying West Systems epoxy by the 4.35 gallon drum:shock:.

I'll take some photos and get something posted this weekend. Thanks for your interest.

Bryan

Can't wait for those pics!:D

By the way, That rocket is HUGE!!!:y:
 
Byran

Doing a big rocket like that is a massive undertaking. I honestly don't think I could do it alone. Not only the time, but the costs involved just in materials. You're right something like that works best as a team and having sponsors couldn't hurt.

I tell you what you have done so far is very impressive...take your time and keep up the good work.
 
1.) Your fins will be very heavy. Glass skinned fins over a honeycomb panel is a professional lightweight solution. Consider making your fins with these 4' x 8' x 1" fiberboard honeycomb panels. Their strong and cheap and will eliminate massive amounts of nose weight.

2.) This rocket will need big chutes, and chute failures are the numbe one problem will big rockets so you should look into professional deployment methods.

There have been several 24" Big Daddys flown in the past. IIRC they all had some damage on recovery. You might consider using 3 chute cannons in the NC to insure deployment. Since the airframe and NC are so large it's easy to do, and you don't need to pressurize the airframe and popoff the whole NC. You can angle (3) 6" to 8" diameter cannon tubes in the NC about 20-30 degrees off centerline. Use an inverted piston or D-bag to hold and protect the main chutes. Attached a 3' pilot chute to pull the mains out.

Another advantage if this method is that the amout of nose weight is greatly reduced or eliminated since the cannons can be in the forward part of the NC and the NC firmly attached to the airframe.

Bob
 
1.) Your fins will be very heavy. Glass skinned fins over a honeycomb panel is a professional lightweight solution. Consider making your fins with these 4' x 8' x 1" fiberboard honeycomb panels. Their strong and cheap and will eliminate massive amounts of nose weight.

2.) This rocket will need big chutes, and chute failures are the numbe one problem will big rockets so you should look into professional deployment methods.

There have been several 24" Big Daddys flown in the past. IIRC they all had some damage on recovery. You might consider using 3 chute cannons in the NC to insure deployment. Since the airframe and NC are so large it's easy to do, and you don't need to pressurize the airframe and popoff the whole NC. You can angle (3) 6" to 8" diameter cannon tubes in the NC about 20-30 degrees off centerline. Use an inverted piston or D-bag to hold and protect the main chutes. Attached a 3' pilot chute to pull the mains out.

Another advantage if this method is that the amout of nose weight is greatly reduced or eliminated since the cannons can be in the forward part of the NC and the NC firmly attached to the airframe.

Bob

Geez, Bob, where were you two months ago? ;)

The fins were indeed just a little on the heavy side (read: 23 pounds EACH), so I had to make some modifications. I looked into foam-core fins, but have never seen the honeycomb you linked. Thanks.

As for the cannon, I am having a little difficulty picturing how that works. I tried a few searches here and elsewhere, but really didn't come up with much. I was planning on a single big chute pulled out at apogee by a pilot on the M-flight and using a Tender Descender for the N plus airstart flight. Thoughts?
 
Very cool project doc, I'll be watching closely. I'm planning a 24" dia PML Lunar Express after I finish the Proton Project we're working on now. Lots of foam shaping, fore and aft on that one. I assume that's your plan for the nosecone on yours? I'll also be sporting huge fins so will look at that honeycomb option Bob mentioned.

Keep us posted ..

Steve
www.smashrocketry.com
 
Don't know how I missed this the first time! Please keep the posts coming.

I like the idea about the mastic/vacuum bag material instead of a regular bag. I might look into that for other projects.

Thanks!

Sandy.
 
Very cool project! The Big Daddy is one of those iconic rocket designs that everybody flies at one time or another. Good luck on making your deadline and your continued success. John.
 
Don't know how I missed this the first time! Please keep the posts coming.

I like the idea about the mastic/vacuum bag material instead of a regular bag. I might look into that for other projects.

Thanks!

Sandy.

Yeah, thought it was going to be a great way to get it done. Turns out that the vacuum pump actually is strong enough to pull air through the spiral grooves of the sonotube and you end up with areas of decreased resin along the spiral grooves. :mad:

I'll post some pics.
 
What do you plan on the launch weight being?

My 20" squat I am working on is about 7pounds per fin. And so far it looks like a final weight of 120lbs +/- 20. I don't think it will launch on an "M". I have a fiberglass MMT what I think will be a heavier nose (not a bad thing in these fat short rockets)

I can't wait to see some pictures and compare it to my Squat. (search squat-o-mania if you havent seen) I definitely don't indorse my build methods (I'm still making up some aspects), but just as a reference.

Have fun.
 
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This is awesome!

Last year, I talked to Vern at a Tripoli Idaho Launch, I asked him how FITS was...his nearly instant reply was about some guy flying an awesome velociraptor upscale for his L3.


I guess he's in for another treat!



Braden
 
Well if extra nose weight is required you could always get in and go for a ride.:D

Awesome project, enjoying the build.
 
Yeah, thought it was going to be a great way to get it done. Turns out that the vacuum pump actually is strong enough to pull air through the spiral grooves of the sonotube and you end up with areas of decreased resin along the spiral grooves. :mad:

I'll post some pics.

Would a layer of plastic taped to the inside of the sonotube help that? would it need to be sealed to the outer bag?

Probably too late now, but as you said earlier, it will probably land on the fins. Have you considered disposable fins? Make the fins attachable and breakaway. Maybe surface mounted so they break off on landing instead of breaking. You would have to reattach for every flight, but might be better then replacing TTW fins every couple of flights.
 
This is awesome!

Last year, I talked to Vern at a Tripoli Idaho Launch, I asked him how FITS was...his nearly instant reply was about some guy flying an awesome velociraptor upscale for his L3.


I guess he's in for another treat!



Braden

:blush: That Vern is one of the good ones! Watching him fly a rocket with Kate on board is definitely a must do.
 
What do you plan on the launch weight being?

My 20" squat I am working on is about 7pounds per fin. And so far it looks like a final weight of 120lbs +/- 20. I don't think it will launch on an "M". I have a fiberglass MMT what I think will be a heavier nose (not a bad thing in these fat short rockets)

I can't wait to see some pictures and compare it to my Squat. (search squat-o-mania if you havent seen) I definitely don't indorse my build methods (I'm still making up some aspects), but just as a reference.

Have fun.

Yeah, Bryce, I've been lurking on your Squat build. You're certainly putting together an impressive rocket resume!

I plan to launch this over Memorial Day Weekend. I'm starting to lose sleep and dreaming about missing the deadline:y:
 
Would a layer of plastic taped to the inside of the sonotube help that? would it need to be sealed to the outer bag?

It would have to be essentially one continuous sheet inside and out. Yes, it would solve the problem, but trying to seal all the leaks would take longer than it takes for the epoxy to cure:(. It's a good idea, though. I've seen it done that way on smaller diameter tubes. I was able to do it this way only because each section is a little longer than the finished tube will be.

As it turns out, once I figured out the problem, the solution was just to coat the entire tube with epoxy, let it cure, sand it with coarse sandpaper, and then lay the tube up just like before. The first coat sealed the tube and allowed me to pull a full vacuum without problems.

Probably too late now, but as you said earlier, it will probably land on the fins. Have you considered disposable fins? Make the fins attachable and breakaway. Maybe surface mounted so they break off on landing instead of breaking. You would have to reattach for every flight, but might be better then replacing TTW fins every couple of flights.

I thought about this, but instead of having them breakaway (which makes me nervous about them breaking away before I wanted them to), I thought about attaching the fins with screws and just making an extra fin or two. I decided to just take my chances with building a strong fin, using a big parachute, and hoping for a soft landing.
 
So when I cut out the template for the fins from RockSim, I realized that the fin shape didn't match the shape of the Estes Big Daddy. I got the file online and really didn't really look at it compared to the original. Fortunately, I noticed the problem after cutting out the template and hadn't cut any of the fins yet. So here is a still-rough design of the rocket at this point:
Super-Big-Daddy-L.jpg


As I indicated, I had some trouble with fiberglassing the sonotube. My vacuum press never got past about -12" Hg. I thought it was due to leaks along the edge of the tube where the mastic tape was placed, but it turns out that the vacuum pump was pulling air through the spiral grooves. This allowed air under the fiberglass and displaced some of the epoxy. Here is a picture showing the issue:
DSC7495-XL.jpg


To solve the problem, I first coated the entire tube with epoxy. After letting it cure, I sanded the tube with coarse sandpaper. Then I laid up the fiberglass onto the tube as before. This time, the vacuum press was able to pull an adequate vacuum without significant leakage. The result is shown here:
DSC7493-XL.jpg


The result is much better. You can still see the spiral grooves that really are resistant to absorbing much epoxy, but there is no leakage.
 
I have been doing a bunch of composite vac-bag stuff and was wondering what kind of pressure you were reaching on your set ups? I tend to be right at 25"hg.
 
I have been doing a bunch of composite vac-bag stuff and was wondering what kind of pressure you were reaching on your set ups? I tend to be right at 25"hg.

It depends. With my vacuum press, I can adjust the vacuum as necessary. For reinforcing foam, for example, 25" will start to compress the foam, so I set it lower. Still plenty of pressure, less risk for crushing. For other stuff, though, I go to 25". Didn't do it for the sonotube glassing because of the issues I was having before. Still worked out fine.

Bryan
 
In order to make glassing the tubes easier, I cut the original 12' section of sonotube into three sections using a jigsaw. This left less-than-ideal edges. I needed a way to cut the tubes to length after they were glassed. I needed these edges to be as straight as possible. I have a 12" compound miter saw for cutting tubes to about 5" in diameter. I built a little wooden jig for my table saw for cutting tubes up to about 12" in diameter (which I used on my Avenger and Velociraptor Rex builds). However, this 24" diameter tube was a different beast altogether.

Here is the solution I came up with:

DSC7500-XL.jpg

This is a cutting jig I made from 80/20 extruded aluminum (the same stuff as most launch rails). In this case, however, I wanted more stiffness, so I used the 2" x 2" "2020" profile for the parallels and the 1" x 3" "1030" profile for the cross members. The frame was built to sit perpendicular to my table saw blade and attaches to the table saw frame via clamps. This setup has the advantage that the tube can sit flat in the jig and the saw blade can be turned on, then raised to cut into the tube, keeping the entire cut edge of the tube square.

DSC7501-XL.jpg

The jig is fitted with parallel conveyor-belt rollers I got relatively cheaply from McMaster-Carr. That place has everything! These allow the tube to be rolled over the saw blade as it is cut.

DSC7504-XL.jpg

Even though the parallel rollers keep the tube square on the blade, the tube can move forward and backward over the rollers, potentially leading to an uneven cut. Since the edges of the tube are not square and cannot be used for a guide, I needed to come up with a way to keep things straight. Supporting the piece in the center minimizes the effect of a not-quite-straight bulkhead inside the tube. The above photo shows the support I made from the 1030 aluminum and a 1/2" shaft I plan on using later. I needed a stop, so I used the 1/2" gear shown as it could be locked onto the shaft at any position using set screws and I didn't have any other appropriately sized stop.

DSC7505-XL.jpg

This photo shows the bulkhead I used when fiberglassing the tubes. It has a hole diameter that happens to be a perfect fit for my 1/2" drive bearing, which is shown inserted into the center hole. The bulkhead is eyeballed in the tube for square. By supporting the center, any errors in the placement of the bulkhead are minimized.

DSC7506-XL.jpg

Here the 1/2" shaft is inserted into the bearing and the stop is positioned against the bearing. This will allow turning of the bulkhead against the stop with little friction, providing a stable guide for the cut on the other side of the rollers.

DSC7507-XL.jpg

This photo shows the tube in place on the jig and ready to start the cut of one end. The saw blade is down so the tube sits flat on the conveyor rollers. The tube is actually supported just off the saw table and rolls easily.

DSC7522-XL.jpg

Here I've turned the saw on and raised the blade so that it cuts through the tube. It does not have to extend far into the tube, just enough to cut through. I don't spend much time on this side of the jig. I pay more attention to the other end of the tube, making sure that the bulkhead remains solidly against the stop. Besides, this side is the dusty side, even with my mask, goggles, and a vacuum pulling dust from the blade.

DSC7526-XL.jpg

Here you can see a nice straight cut starting. The tube is rotated counter-clockwise in this angle so the blade cuts correctly. You can see all the dust flying around, even with the vacuum system hooked up. A mask and eye protection is a must, especially since there is fiberglass dust there too.

DSC7527-XL.jpg

The first end has been cut. This method produces a very straight cut with minimal effort.

DSC7534-XL.jpg

Here you can see where the cut started and stopped. There is a slight offset of about 1/64" or less. Not bad considering the saw cut the entire 77" circumference of the tube. A little sandpaper and this goes away.

DSC7533-XL.jpg

Since I now have a tube end that is straight, I no longer use the bulkhead and bearing setup as a guide. The support provides an adequate guide for cutting the second edge. The cross member holding the guide can be loosened and slid into position without disturbing the rest of the frame. The straight edge of the tube glides along the anodized aluminum without difficulty, producing a clean edge on the other side as well.

DSC7536-XL.jpg

This is my first time working with Sonotube. I found that it delaminates very easily on the ends. I therefore treated each cut edge with thin viscosity CA glue to prevent delamination. Thin CA is nasty stuff. When applied to an edge 1/4" thick, it smokes quite a bit. This is hard on the eyes and on the lungs. I therefore use a respirator and full goggles when doing this.

This is my first time using this tube cutting jig. It can be easily adjusted to accommodate any size tube up to about 26" in diameter. I can cut larger tubes by replacing the cross members with longer sections. Although it was a bit of work to build and set up, the results were very satisfying and I can use this on future projects with minimal modifications. I can also use it to cut fiberglass or carbon fiber airframes using the appropriate table saw blades.
 
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