S200 ANGARA/SA-5 GAMMON Build, Finally!!!

[TopRamen]

OK, the 11.357 scale factor is based on the sustainer diameter (29.528") divided by your BT-80 diameter (2.6"). The booster tubes would then scale to 1.532". The closest tube I find is a BT-58 (are they still available from Semroc/eRockets?). You are going with the BT-60 (1.637") so the booster scales will be 1:10.63) ... try printing the updated pdf file at 11.357/10.63 or 106.8% and see if that helps.

You might try basswood or spruce for these puppies. I made some SRB standoffs for another project out of balsa, and the kept breaking off along the grain..or you could sandwich some balsa sheets together w/ the grain at 45 or 90 degrees for strength.

Thanks for the tips about the wood. Guess I need to come up with some techniques to sculpt it, and start practicing.
Must be some youtube videos I can go watch.

I kinda' figured my way around how to mount the exhaust nozzle.

 

[rocketguy101]

You might try stacking smaller blocks together and blending them...I went nuts trying to figure out how to make the struts that connect the Soyuz boosters (just found this excellent view of one during assembly)...I finally came up with the idea of stacking dowels together...

 

[TopRamen]

That's a good solution.

I have a good picture of the forward lugs.

Thanks Torkemado for the pics.



The bottom booster has the big ugly horns.

 

[Sooner Boomer]

Thanks for the tips about the wood. Guess I need to come up with some techniques to sculpt it, and start practicing.
Must be some youtube videos I can go watch.

I kinda' figured my way around how to mount the exhaust nozzle.

To try "sculpting" parts, I highly recommend Sculpy or Fimo clay. They cure hard in the oven at low temp.

 

[TopRamen]

To try "sculpting" parts, I highly recommend Sculpy or Fimo clay. They cure hard in the oven at low temp.

That's a good idea too.
I could put a bamboo dowel/shishkabob skewer inside for strength, between the booster and sustainer.
I don't have any clay handy right now, but will get some to try.
I remember in high school, all the hippy kids liked fimo clay to put on their smoking devices.:lol:
Never heard of sculpy, but I'll look into that too.
Gonna' go check out some youtube videos and see if I learn anything useful.

 

[TopRamen]

I watched a bunch of Youtube videos that showed folks making their own molds for small parts out of things like silicone caulking, and they would then use resins of various aspects to cast the parts.
I feel that something along these lines is worth further investigation. At the same time, i will need to make some "Positives", if I am to create a mold in the first place, and so I will see what I can manage to create using basswood, paper and fiberglass first.
I theorize that both the forward and aft lugs/legs, would be best made as single piece units, each pair mated to a section of the tube to which it would eventually be mated, as this will make insure the spacing between the lugs stays consistent, essentially having two lugs per booster as opposed to four.

Another issue that now presents itself, is that like the rear sustainer fins, the rear lugs that are presented in the CAD file are arbitrary to it, and do not match with actual pictures of the lugs.
I had made some transitions, then stuck a dowel through them, filled them with balsa sanding dust, then super thin CA.
I will sand them to shape today and see how they look and match up. They would be ideal weight wise, not to mention easily reproducible.

View attachment 285075

 

[TopRamen]

Well, after a long day, beginning with having to do a lot of driving, which I hate, I finally got around to tinkering a bit.
I put one piece of 2oz. Glass cloth between 2 pieces of balsa cut to the dimensions of the booster fins, then, glassed my tail cone for the sustainer with a single wrap of 1.5oz. glass cloth.
The test fin is under a heavy book, on a smaller slab of marble, to cure til' tomorrow, and when it is ready, I will be able to practice sanding the facets/angles I need with it. I made myself a "T-Bar" sander from basswood stock, 9" by 1.25", and that should be perfect for the facets on these small booster fins, I hope. Like everything else with this build so far, I feel it is important to futz around with "practice versions" before commiting to the actual model parts. I know I can build it, but it is complex, so I may as well do it slowly and not just hack it together.
I'm ok with it taking more than a few months to complete. I have decided I need to learn to mold parts for this build, and that in itself is an entirely new skill set I'll have to master, but Youtube videos and reading will get me up to speed.

Anyhow, here's my tail cone sitting up on a shelf where it can't be disturbed and is out of the way, resting on some parchment paper.

 

[Rob702Martinez]

I'm really looking forward to this, I've also learned a few things too! Keep it up TR!

 

[TopRamen]

Thanks Rob!

I got the excess glass and the masking teflon tape cut away from the cone. Later, when I have time, I'll seal and sand the edges and tune it up nice, but it should be good to go as an actual part and not just a practice run. That's why I love FG Cloth, it is easy to work with and predictable.
It is so relaxing to work with.
I have already made the narrow transition paper pieces to connect it to the booster ring, and may get around to fitting those and glassing them to the cone later.
Using an inner wall, and then covering that with the finishing epoxy too created a very rigid piece.
It now weighs 13g., so glassing in this manner only added 2g., and that is before I sand away the excess epoxy, so it's probably more like adding a gram and a half.

 

[TopRamen]

I did some practice making the faceted booster fin.
2oz. glass sandwiched between balsa, then sanded to shape, sort of. I need to practice.:blush:





I do really love this glass sandwich technique I learned from Sunderll's thread in the techniques section. The edges are as sharp as a knife!

I'll be using this on all sorts of builds now, and have a LPR Crossfire ISX build going on the side that will look pretty sick with properly faceted fins!

 

[dixontj93060]

I need to practice.:blush:

Doesn't look bad to me.

 

[TopRamen]

Doesn't look bad to me.

Thanks.
I'll have a few more goes at it then I should have a technique figured out. Just have to "Get the hang of it", and maybe use some form of masking next time instead of drawing lines by pencil and then expecting to not accidentally sand through them.

If you look at the last pic' on the trailing edge near the root edge, you can see where I sanded too much, exposing the fiberglass core.

This one will give me a chance to test my new "Neoprene Fin Contour Press" method of applying the glass to the fin. Theoretically it should work, but it's raining outside so I won't be cutting any glass cloth tonight.
It'll probably look ok after a layer of .75oz. and some primer and Bondo.

I think I will make a jig, similar to this one I used to use sometimes to profile blades when I used to make knives. This will allow me, in conjunction with some form of masking, to make consistent angle passes with the sanding T-Bar.

 

[TopRamen]

This morning I got back to working on the fitting of transitions for the tail cone assembly.
I found a profile I like that keeps my measurements correct, and got it right on the first go, meaning I did not waste any of my cardstock.
I took this transition outside and hit it with the CA. It is very rigid now.
To mount the whole thing together, I will cut two more transitions, one slightly larger on the inside and outside dimensions, and one slightly smaller but only on the inside dimension.
The first of the seconds, will go in front of this one, to cover the edges of the ring that attaches to the booster lugs, and the second, will go behind it on the inside. Between the three transitions, on either side of the central transition, will go a single layer of 1.5oz. glass cloth with 20 minute finishing epoxy for strength. The boosters exhaust cones will be the first part of the rocket to hit the ground on recovery, and they will transfer that shock to the tail ring, so this assembly must be strong as well as lightweight. When the assembly of the tail cone ring/transitions is complete, I will use 1 or 1.25oz. cloth on the outside of it.
I'm quite proud of this arrangement of parts, and my approach to making it.

Here's some "Dry Fit" pics' of what I'm up to.:

 

[TopRamen]

Last night, right before I fell asleep, I had the idea to use the angle diagram from the excellent cone templates that Rocketguy101 made for me as a template for an internal rigid support structure.
Making it out of balsa, and hitting it with the super thin CA, rather than stuffing the cone with tissue seems like it can be made more consistently, and should add less weight. This also will make the cone perfect at the angles that are critical.
My first attempt at learning to make the oblique cone required lots of filler to bring to acceptable appearance. I don't want to be doing that on the actual model, as I need ALL FOUR boosters to be within a couple grams of each other for balance purposes. The outer surface of the cone will get the lightweight glass anyhow, so filling the insides with CA soaked tissue as a means of enhancing the durability is not even necessary.
I don't plan on abusing the rocket, so it does not need to be bullet proof.
This newer method also lets me sand the seam away after I soak the thing with CA, again, meaning less fillers.
On this particular cone, before I shaped it, or even added the tab, I very gently sanded it on both sides with 180 grit sandpaper to open up the pores of the cardstock. In the past, I have neglected to do this, even though I always have considered trying it. I tried it today on the first transition I made, and was VERY satisfied with the results. The CA, rather than run and leave a drippy pattern on the piece, absorbed in a much more consistent fashion, meaning less was needed and wasted. From now on I will gently "Surface Prep" all cardstock parts in this fashion.
This also made the cardstock noticeably easier to get shaped, requiring only holding it above my steaming coffee for about 10 seconds.
I must stress that only the lightest pressure was applied while sanding the paper, just to scuff it the slightest bit. I will in the future be trying a scotch brite pad for this step, as my intent is only to remove whatever it is that inhibits the absorption of the CA or finishing epoxy.
Anyhow, here's what I cam up with, and while this one is not perfect, it is just another practice and proof of concept, and I think the method will be suitable for the the actual build. It is certainly light-years ahead of my previous method.
Further, I imagine I can extend the balsa part that protrudes from the bottom of the cone about 1/2" into the body tube of the booster for attaching the two.
Anyhow, here's what it is, and sorry for the crumby pics'. Current camera is a piece of junk.

 

[rocketguy101]

I like it!! Extending the balsa rib to make a "shoulder" is a great idea, and I will try the surface scuff before CA technique next time.

 

[Cl(VII)]

Thanks.
I'll have a few more goes at it then I should have a technique figured out. Just have to "Get the hang of it", and maybe use some form of masking next time instead of drawing lines by pencil and then expecting to not accidentally sand through them.

If you look at the last pic' on the trailing edge near the root edge, you can see where I sanded too much, exposing the fiberglass core.

This one will give me a chance to test my new "Neoprene Fin Contour Press" method of applying the glass to the fin. Theoretically it should work, but it's raining outside so I won't be cutting any glass cloth tonight.
It'll probably look ok after a layer of .75oz. and some primer and Bondo.

I think I will make a jig, similar to this one I used to use sometimes to profile blades when I used to make knives. This will allow me, in conjunction with some form of masking, to make consistent angle passes with the sanding T-Bar.

View attachment 285387

I consider myself advanced in the art of duct tape and bailing wire construction techniques, however after seeing that jig I bow before the master. Function before form everytime.

So no one gets confused, as you can't read tone on the internet, consider the above a compliment, and it is no way meant as sarcasm.

 

[TopRamen]

I consider myself advanced in the art of duct tape and bailing wire construction techniques, however after seeing that jig I bow before the master. Function before form everytime.

So no one gets confused, as you can't read tone on the internet, consider the above a compliment, and it is no way meant as sarcasm.

I was actually waiting for someone to comment on my duct tape prowess.:lol:

Duct taping the guide to my bench grinder was just the easiest solution at that moment, rather than make a proper guide that mounted to the holder in the vise.

But yeah, sometimes you just gotta' do what works, even when it's not pretty.

 

[TopRamen]

I like it!! Extending the balsa rib to make a "shoulder" is a great idea, and I will try the surface scuff before CA technique next time.

I think you'll be pleased with the way the CA meets the paper as opposed to if you don't scuff it. Any sanding scratches visible in the pics' I posted were from the sanding I did after treating with the CA. Like I said, I was very gentle when sanding the un-worked part, as I did not want to score it, just do what I could to get more uniform penetration.

Thanks again for the templates! Had I made them myself, if I could have figured it out, I would not have had the triangle, and perhaps then would not have thought to make the balsa support.

When I close my eyes at night, the schematics and designs and everything sort of floats around in my imagination, and when I wake up, it seems that rockets are the first thing on my mind too.

 

[TopRamen]

I got the second of the three transitions that connect the tail cone to the booster lug ring cut and lined up pretty well. I'll CA it tomorrow, well technically today, but after I get some sleep so I can start fresh. Then I can fine tune it. Once that is done, I can start making the third transition.
Like I said I'de do, I simply printed the same transition, but cut it a lines width larger on the smaller section, and three lines larger on the larger outer section.

 

[TopRamen]

I've decided to use these little metal clips I found at tthe hardware store the other day to be the main structural load bearing member in the junction of the boosters to the sustainer, and since I got 20 of them for $1 in the clearance basket, I have enough to chop them down to their bare minimum to keep the weight within tolerances. They are good because they are all identical. There is obviously more metal there than I need, so I'll remove the parts that don't fit, then cover what does with some form of clay or maybe even just glass cloth then primer and a little clay to meet the looks of the real deal. I can drill and tap them if needed, or make holes in them to attach them to the sustainer with wire or springs, making them a serviceable and modular component. Perhaps someday when I'm L1, I could make working boosters that can jettison at a specified point, and the sustainer would airstart, just like the real deal.

Anyhow, here's some of my balancing the dry fit parts together. Even though they have not been fine tuned, the all fit pretty level and snug.
It's definitely going to look cool with three more boosters. This one is not even the right length, but it's just a practice one anyhow, so never mind the discrepancy in the length if you notice it is a couple inches short.

 

[rocketguy101]

That is really looking cool! The metal brackets are a great idea, can't beat the cost (well unless they were free )

 

[KidRockET]

Very nice work being done here...

 

[CORZERO]

Flight video?

Oh... Wait... Ha just kidding

Great build! Kits are cool but end products which require the ingenuity and brain steam necessary to scratch like this are much more impressive/fulfilling to me. Keep up the good work, this rocks!

 

[TopRamen]

Thanks guys!

 

[TopRamen]

Off to a slow start today, but I did do some revision to my OR file to more accurately reflect the tail section, then ran some sims with 24mm Composite motors to see what happens. It will be nice to be able to fly this with an adapter on smaller fields.

View attachment SA-5 Gammon Rev8.ork

 

[TopRamen]

I've decided that I'll need to create a Jig to assemble the tail cone/booster lug ring assembly.
I can line the transitions up pretty straight by eye and all, but when it comes time to put the whole mess together, it needs to be perfect.

Once the tail cone is joined with the booster lug ring, I can start making decisions about the positions of the centering rings for the motor mount and that will help me decide where to cut my slots on the body tube of the sustainer, as the centering rings I am using are slotted.
I'll need to make up my mind on the brand of retainer when I get to that point, but I'm leaning toward Aero Pack.

 

[cavecentral]

I clicked your profile picture thinking it was a new picture on your post. Trying to see what size motor mount this beast will have. LOL.

 

[TopRamen]

I've re-thought the legs/lugs for the boosters once again, and want to see what I can come up with by using the clay molded around a bamboo skewer or a wooden dowel. If I can get a couple of nice prototypes made, I'll bite the bullet and pay someone to 3D Print them.
Whether or not they can be printed lightweight enough is irrelevant, as I can always drill little holes through them, then simply glass them.
Additionally, boring them through to be able to run a bamboo skewer through them will add strength.
I have plenty of time to come up with something.
It's a shame that the parts in the CAD file are based on the drawing and not the pictures of the real thing, as like the rear fins on the sustainer drawing, they are arbitrary creations.
When I design the forward and rear lugs, I will try to make them each one piece deals, that the booster body will get set into after they are first mounted to the body of the sustainer. This is especially important in the case of the forward lugs, as the bracket that holds them on the real deal is counter sunk into the body so as to be flush after booster separation. It is a really cool looking feature, and it would be a shame to omit this detail from the model.

I have come up with a very clever way to make the bodies of the boosters.
I will use the to my scale drawing to make wraps, that way all the lines on each booster body are identical, and they will cover the spirals on the tube. Once I make the template, I'll go to Staples and have them print it for me on a lightweight paper, so I can have more than plenty to make many boosters. The lines will allow me to easily index everything that attaches to the boosters like the bit near the top with the bolts that hold the cone on. adding the details like the bands will also be easier doing it this way.

 

[Rob702Martinez]

Have you seen the fliskits thunderbird?

 

[TopRamen]

Have you seen the fliskits thunderbird?

I've recently done more than see it, as I've been researching all the threads here that involve it to see how folks have done it up.
Forum member Adrian even made a scratch built Thunderbird that jettisons it's boosters!!! Amazing!

https://www.rocketryforum.com/showt...erbird-Gallery&highlight=Fliskits+Thunderbird

I was thinking about getting the Fliskits Thunderbird, as it is only $24, and I would like to see what happens if I make one booster weigh more than the others by a few grams, to get an Idea of how perfect my boosters need to be balanced.
The Fliskits would be a good test platform for this, and since it is a kit, if it crashes and burns I would not even care.

One item of note about the Tbird though, is that there is no gap between the boosters and the sustainer. This would mean it would have different flight characteristics under windy conditions, but I usually run from the field in the slightest of breezes, so this might not really be an issue. The real Gammon could launch in a wide spectrum of environmental circumstances, so I suspect it is actually an improvement aerodynamically over the Thunderbird design.