Super Big Bertha 24mm D motor max...Had booster idea. Now a tail transplant to 29mm.

[86mustang408w]

Found a spool, that I wanted to make a booster section with first out if stuff around the house. That will work and be really cool. Bit then I got to thinking after cutting the tube slots why not just cut thr top off and put a new tail in? I looked for fins with my last RocketyWorks order just a few days ago, and I have 1/4" I got 10 years ago from Balsa machine to make my own ejection baffles. But using it for fins now..Some pics below. Gonna sterilize the knife now..Ask question sim not typing it all out..

 

[86mustang408w]

Time for sanding, skins, glue, then paint!

 

[86mustang408w]

Heres that spool I found, and the D 24mm tube and hook. It fits perfectly around the motor and hook for a booster section.. Its perfect too all the way against the bottom centering ring. They would ensure a straight flight and the body tube and coupler would almost just be to support the outside of the rocket. Justba way to add a booster secrion to one. Or it could be used to make a motor adapter for 29mm to 24mm motors somehow...But fins are cut out, and glue is next.

I added some pics again. But in a little bit of an order so you can see what my thinking was and is. Over the random ones blasted out above..

 

[86mustang408w]

Got the fins glued the the poster board skins and weight on them now with wax paper in between each fin. Once they dry a little more ill get them trimmed better and sand them a little. Also got the yellow tube sanded down with a coupler inside to give me straight line to go by. I might not but it completely together and leave it apart justba little bit so the coupler lines the the yellow tube with tr new tail section. I don't need a eyeletnin the top centering ring. The ejection baffle had that in it. Its a bigger holed baffle it will be fine and I'm not going to put anything big in it. The 29mm just opened up my options over making a booster or friction fitting an E. Which would have been fine. But thought a 29mm option will allow me too to run my 3D printed adapter and blackpowder pretty easily. Once I get the fins done ill be able to cut the tube slots a little longer. But ill go one at a time and mark them as they are just a little bigger than the holes. So one at a time ill fit them in. The top centering ring is already tacked in place with CA. Once I get that in I need to remember to add the couper and the rail button that up top. Then the aft button and fillets will be done before the aft centering ring is added. Then outside fillets then dry time with sanding an paint after.

 

[86mustang408w]

Now that I have the top ring tacked with CA for mock up fitting purposes, and the the fins are drying. I measured the distance from the bottom of the motor tube to the top and bottom of the forward centering ring and narkednit on he outside body tube. Once its all togetherill drill a small hole and inject epoxy on the top to help with blast deflection, and on the bottom for extra strength. I'm sticking with 3 centering rings, and might use a 4" coupler I have. But then I'll epoxy the top ring to the tube. Have to slide it in, put in the rail button, the the coupler, and finally do the second ring and so on while its hang out of the tube.bIbwont glue or epoxy anything until I'm sure and its necessary. CA is nice, if you need it moved you can break that little bond. I'm going to wait until 2morrow to sand down and trim the fins. Once that is done ill go one by one and cut out the tube slots a little longer so they fit if need be. So for now I'm held up with this, time to finish Crossfire ISX E.

 

[86mustang408w]

Fins are done. Need to sand and fit today. The tips are off a little. Might snip the ends off, or just leave them be. They are not off by much and it would make a mess trying to fix something small like that. Updates later on.

 

[86mustang408w]

Got the fins sanded down and shaped for Super Big Berthas transplant. I made another foam jig so I can glue and not worry about the fin angle, but it still need a little tweaking. The fins pretty tough with skins on them, its still impressive even being balsa what adding glue and poster board does for strength. The skins add so much strength its ridiculous. But assembly should be soon, I'm taking my time with it as a few important steps need to be done. Like installing the rail button after the top centering ring goes past it, and a coupler between that top ring and second one, etc... I was going to leave the aft centering ring about .750" down the motor tube from the aft motor tube end. Im probably just going push it down against the fin tabs to give it a little extra help. Its only about an inch down down total. When I made this I was planning a different build, it was going to be a booster section but I liked it too much. Then it made sense at that point just to swap it out. A little more fitting then its time for adhesive, and then I'll seal up the fins and motor tube after thats all done with the aft centering ring. Seems to be turning out ok so far. The tops of the fins are not the same length if you stand them next to each other. But after looking at them, all the skins are its just the balsa thats a little short. So it would be easy to fill in those root chord "tips" on the rocket to make the tops of all the fins the same height. I might do that or cut a fin like the foam board in the last picture so you can see what I mean, but im not sure yet..

 

[86mustang408w]

The centering ring is down against the fins tabs. Best to leave it like that. I should have made them longer but with my other booster plans in ny head didn't by just a half inch or so. The motor retainer also pictured.

 

[86mustang408w]

Looks like assembly later today.

 

[86mustang408w]

Super Big Bertha Update...

Got the rail buttons in, I left the lugs so I can launch it too easily. Got backing plates on and its just basically sitting there mocked up, again. I like them if you ever need to change the screw at least the plate will hold the backing nut in place. Time for assembly as soon as I figure out how I want to put it together, might sit and make a checklist so I don't miss anything. But I've run thru it a few times and I'll do it again, I did use marker. But I need this to line up and to see it easily. Also felt it was best to keep a very little gap at the coupler between upper and lower body tubes. The rocket is straight all around like that. Ill fill it in, also started the motor tube and centering ring fillets. Gonna flip it upside down and do it again. I'm using Titebond Quick and Thick to save over epoxy and extra weight. I'll have a few pressure vent holes to help out when I use composite for the air pressure change going up, and also use them to inject some epoxy on that top ring after its all together. I marked the position of the top CR too, so I know where to drill at to inject the epoxy in the tube. Ill also put another smaller vent hole in the top. Its got a baffle and I feel on a composite going up that quick it will have many places it will need to vent that sudden pressure change. And I don't need the nosecone popping off so all high power must have them, as I was advised myself. Might even do it for some smaller low power rockets. Think I might get it assembled tonight. I still have lugs but it will be fine like that, I would prefer they be a little further apart. But its not gonna happen on this build...

 

[86mustang408w]

Flipped the motor tube and did a fillet on the bottom. Ill let that dry over night. Thats the only thing at this point permanently attached.

 

[86mustang408w]

Here's a few pics of SBB, what it looked liked before the yellow paint and fixes, and after. It will be the same colors(Yellow/Black) again. Soon!

 

[86mustang408w]

I sat down and think the best way to assemble it is to put the coupler on and glue the 2nd centering ring in(The top ring is set but the coupler has to be in between the top and 2nd ring for assembly either way I do it). Then install the top ring in the yellow tube, and then the top rail button. Ill do the coupler in the yellow tube first with glue probably 2morrow. Then the lower section onto the yellow top and coupler that is already in between the yellow section and new tail section. I'm leaving a gap too pushed together the sections are off(so ill use the coupler to make sure its straight by leaving a small gap to make up for my minor inconsistencies in cutting an making the tubes square as I could.)It gives me the best way to line up the tubes to make sure the rocket is straight. Then I'll do the fins and make fillets on the inside middle ring. Then install the aft rail button. And when its all done(internal fillets)the aft centering ring then retainer with JB weld. After that outer fillets, primer, and maybe a test flight before paint to see what it needs before I attempt to make it shiny again. So, I did sit for about 45 mins and mocked up both ways step by step and doing the tube into the top and then adding the fins is much better than assembling the whole tail section then trying to get it on the top. It can be done I already measured out that way it was my thoughts when I started this is which way would be better. After doing it the assembly on the tube is best, rather than entire assembly then try to glue to top to the bottom. I still need to maybe mark the motor tube where the fins will go at least with a marker on the tube end soni can make sure they are lined up with the jig. If that all good ill start fillets soon. I also checked to see if i could do the aft rail button with the motor tube in, yeah theres room. So that will go it probably after or during internal fillets.

 

[86mustang408w]

That ways best. I tacked the top ring so it doesn't move. Then I'll do a fillets tonight with thick and quick. Thats stuff is amazing..

 

[86mustang408w]

I cleaned the excess glue off that fillet so the fins fit in. But I wanted a good bond on that ring.

 

[86mustang408w]

I flipped the tube and did fillets on the centering rings to the motor tube. I also scuffed the tube some time back with 100 grit to rough it up a little. Glue is plenty for this build. Epoxy will just be added weight and defeats the purpose really of flying this on smaller motors at my launch area. I'll add epoxy in certain places that will take the ejection blasts, but other than that its Titebond Q&T pretty much for this build for external fillets. And probably Titebond II for inside fillets and fins to the motor tube. The 29mm option was just to open up a wider variety of BP motors over the booster section. That would have worked, but also would have limitations to just 24mm D or E motors that I have. Honestly I wanna see how much this thing eventually will consistently take 29mm motor wise. But for now, you can see how thick it goes on and how it dries very hard to see(the tube is flipped on on two different way in the picture but they all were that thick, and dried clear. But its soild glue and easy to work with. And the coupler had to be in the middle of the top and middle CR's.

 

[86mustang408w]

Well I was gonna put the motor tube in and glue the plywood plate on the top rail button in, then do the upper coupler. But forgot I wanted to get that old ring out of the yellow tube. So I hit that hard, but not enough to hurt the rocket in one spot with a dowel rod. Same one I'm gonna use with an exacto knife taped to the end to get/cut that out. So the ejection blast will go right to the ejection baffle. Then ill glue the backing plate in, and coupler, and then tail section.

 

[86mustang408w]

I made a little dowel rod hook and pulled that CR out. Gonna clean it up a little more but its pretty much done. I'll be doing the rail button soon, and coupler. Probably let it dry until 2morrow then.

 

[86mustang408w]

I used that stick and got out as much as I wanna get out. I thought about running a kelvar shock cord thru the baffle somehow. But don't think it will last with the line in the baffle. Its kind if an odd mixed build now. But if anything I can drill a whole thru the top of the baffle for composite motors and ejection venting. With that long body tube im not so concerned about the exhaust gas pressure being too much for that baffle(I'm also going to have pressure vent holes that will help too with this. But not many and very small if they are needed now). And if I am, I can adjust. But im not gonna put anything big in it. The motor tube is just that long to get a good connection inside the yellow tube to the new tail. But if it handles or doesn't handle the blast. I can drill one big hole in the middle of both baffles with a drillbit extension, and make a new anchor point for the shock cord. But this seeing anything over an F motor probably will not happen. Im not into intentionally destroying my builds.

 

[86mustang408w]

I used my syringe and got two nice little fillets on the rail button backing plate inside. Once that dries Ill do the coupler to just the yellow tube tonight. I could do both upper an flower tubes at the same time but I need this to line up exactly, so baby steps. Im just taking it one step at a time. Ill leave the rocket sit in the cradle or stand so the rail buttons are downward like the photo, once its dry ill do the coupler and let that dry until 2morrow. Hopefully ill get to my Crossfire ISX E, JB weld fillets now while this dries or at least figure out how I want to do that..

 

[86mustang408w]

Got the coupler in place with elmers carpenters glue in the top tube. So that will dry overnight. I'll do the lower half 2morrow and definitely use a little water in the glue so I can move it need be easier. So thats it for now...

 

[86mustang408w]

Well the top coupler I let dry overnight. I just used some slightly watered down glue to help with assembly. I mocked it up a bunch of times. But it still can be easy to mess up especially with couplers, but the tail section is on now, and its just about as good as it will get. I did my best to wipe any glue off the yellow tube but it will get re-painted anyways. The motor tube is still "free floating. I didn't want it permanently attached until I knew this was good to go. Any little mess up would have been ugly. But this part was kind of nerve racking but it worked out well. Marking the tube and dry fitting things several times, was a great idea. Plus sanding down the tubes or centering rings a little will help with installation. Once this drys ill start the fins. And probably the middle centering rings I'll hit in a few spots at the body tube on the inside to hold it for sure. Probably later today ill start the fins once this is dry, and internal fillets. I also put two tape tabs on the aft centering ring to make sure the tube was straight and make it easy to remove the CR if need be for any odd reason. And as planned I left a gap, as not to butt the tubes together but let the coupler make it straight. The rocket does have some crash damage up top, but not anything that will be horrible to watch fly. It might go a little to the left or right, but ill be prepared for that and start low with test motors. Like I said there won't be any crazy motors going in this. Just enough to get it high enough for a successful flight and recovery and the 29mm option was just best allowing me to fly many different motors in this starting at A D12-3, that allows me to fly BP motors too with that 29mm to 24mm adapter. I also have to do the aft rail button, im just not sure when yet. I already mocked that up. It could be done really right before I seal that tail section up with the aft CR. Updates later.

 

[86mustang408w]

Once its all dry ill fill in that gap in the tubes after I sand it all down before auto primer/filler goes on and final touches before paint starts. I'm not sure what I'll use, I have some sealer that would be good. But might wrap tape around the tube at that spot. Then cut a hole in the tape or just leave a gap then pour warm epoxy down in that or glue, and make that gap disappear. I have Gorilla wood filler I could use, and I might that stuff works really well too. For now like I said above its still drying. And I'll start the centering rings to body tube later....Super Excited, definitely gave this old girl a makeover for sure...

 

[86mustang408w]

I put the jig on, to check it out. Looks ok but im going to check it all again and make sure that foam jig is straight degree wise. If not ill adjust it and use painters tape to hold things until I get some spots glued. I just put it in it to get it out if the way from another project. The motor tube is still not glued in place at all. Ill probably take the fins out and do that first. To ensure nothing moves when I do the fins.

 

[86mustang408w]

I looked at the jig. Two of the fins(horizontal left and right)are off and one needs to be moved down. Gonna mark that now. But the fin tabs are not 100% perfect but it will work. Ill get the jig right, make sure everythingstays in place with tape if need be, middle centering ring glued in place, and then do inner fillets and the aft rail button, aft CR. Then paint prep.

 

[86mustang408w]

The coupler is well and dry. So I hit the middle centering ring in 4 spots. Ill let that dry then ill do the fins and inside fillets. Since the motor tube isn't realy held in place yet this is the start. Once this dries I'll probably drill holes and inject glue or epoxy above and under the forward CR. I might do that tonight after this dries a little to give it a permanent home. Then 2norrow ill flip it and do the other side of that top ring. Then, probably Friday I can get to the inside and this weekend wrap this up assembly wise. I'm going to probably use Titebond II for the inside then Quick and Thick like I probably mentioned above for outside fillets. Just need to keep myself motivated.

 

[86mustang408w]

I needed some and wanted some pressure relief holes in SBB, so I did that. And some of my others, got most in 2 spots. The Big Dog just one.

But back to Super Big Bertha, I got some glue in my handy syringe I've had for about 12 years, lol. And flipped the rocket up-right and injected the glue. I spent a few mins holding and rotating the tube before setting it level. I out some extra glue in it should make a nice seal. I can't see it but im sure its fine. Any spots I may have missed are now probably covered as I kept rotation going at various angles and its level now. That will dry, then ill fix it and do the exact thing to the other side of the top centering ring. Then in a day or so ill start the fins. But I want to make sure the motor tube is held in place before I start the fins. I cleaned out that hole with a Q-tip as it will probably stay open as a vent hole. With the use of composites those vent holes are a must now for me. Dry time again...

 

[86mustang408w]

Sat down and made a smaller more accurate fin jig. Much happier with the way they are now. I sanded down fin #3 so it fit a little better. Everything else looks good. I'll probably start one fin at a time, and just go one by one getting them primarily attached. Then after they are done and it place, ill finally get to fillets inside, and then out. I'm going to put in the aft rail button too, before the aft centering ring goes on but not for a bit yet. So probably start with fin # 1 tonight...

 

[86mustang408w]

I got fin one glued on the tab and root chord. Ill do them one by one until they are all like that. I faced this one down to help the tip of that tab it had a little spot of the balsa that broke off on the end. This way is will drop downward and make that bond a little better. I still have to do the lower side of the upper centering ring but ill do that when I nose work starts and its facing upwards(tail section up for inside gluing) for a little bit.

 

[Hobie1dog]

coming along nicely