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-   -   Russian Sa-5 (http://www.oldrocketforum.com/showthread.php?t=17338)

JumpJet 06-20-2018 10:54 PM

Russian Sa-5
 
7 Attachment(s)
It's been a while since I have posted anything scale in nature so I thought I share my latest scale build for NARAM 60. I originally wanted the four strap on boosters to come off once the motors were spent, thus allowing the center portion to continue on its way. Now I know it can be done but I decided to go the safe route and hopefully get a qualified flight and leave the boosters connected for the entire flight. It’s taken me weeks to get these parts grown making MANY changes along the way. Even now I am 3D printing a new nose cone and tail cone since they are a little off. If you look close the fins have steps in them which will need to be primed and filled in to make them look nice. I figured I'll have a good 20+ hours of just finishing work to all these plastic parts before they are nice and smooth.

The four Main Large fins will be built out of a thin plywood center core with balsa sheets on either side, that will be tapered to the correct shape. I will assembling and shaping these wood parts most likely over the weekend. If all goes well NONE of the 12 fins on this model will be glued in place along their root cord. They will instead be bolted in place similar to the real one so there will actually be a gap between the root edge of the fins and their mating surface.

The center body on this model is 2.7" in diameter. The boosters are 1.56" in diameter. Overall length is 38.8". The four booster pods are set up for 18mm motors. I plane on using Estes C6-0 motors in them. For the Center core I’ll looking using an Estes 29mm F15-4 motor. If the model ends up on the heavy side I'll switch out the center motor with a F26 motor. The model doesn't have to go high for the competition, I just need to get all five motors lite and recover the model safely.



Here is a link to a nice video of the SA-5 on the launcher and being launched.

https://youtu.be/NKFqGHlgcI8

John Boren

eljefe 06-21-2018 12:16 AM

Looks like the makings of a beautiful rocket! When can I look forward to seeing it in the Estes catalog? :D

surdumil 06-22-2018 09:43 AM

Very impressive scale project, indeed!
What kind of filament are you printing the final parts with, if I might ask?

teflonrocketry1 06-22-2018 09:53 PM

John,

What model of 3D printer are you using, and what type of filament? Based on your pictures it looks like you are using too high of an extruder temperature and printing at too high of a speed.

JumpJet 06-22-2018 10:54 PM

I'm Using PLA filament. My printer is a Tevo Tornado. I'm new at this home 3D printing stuff. My print speed is 60ms and the temp is 200C.

John Boren

teflonrocketry1 06-22-2018 11:53 PM

Nice 3D printer! I am also new to 3D printing, but have made many hundreds of parts over the last few months. I suggest you use a printing speed of 50ms. I also noticed some of the PLA filaments I own print better at higher temperatures around 220C, you might try increasing the extruder temperature. I have a small BT-20 nose cone design that I print as a test case (30 minute print time) to check the performance of my printers. What slicing software do you use to generate the files for the 3D printer? CURA? Also you might check if there is any play in the printers X or Y axes. If you find any wobble in the bed or extruder platform you need to adjust the eccentric nut on one of the wheels that rides over the v-slot rail on the sliders to eliminate the play. There are so many settings that it is difficult to adjust everything, but once you get a 3D printer dialed in you are usually good to go for awhile. You should look at things like the "jerk speed" (I use 10ms) and if retractions are enabled. I suggest using a filament retraction before printing outer walls. Take a look at the picture in my post on the Estes Python http://forums.rocketshoppe.com/show...736&postcount=2 and you will see the kind of quality you can expect to get from a (cheap $10/kg) PLA filament.

surdumil 06-23-2018 06:49 AM

Thanks, John. I've been messing about with a Prusa i3 Mk2 for a bit less than a year, now, experimenting with different filament materials and manufacturers and print settings. I'm finding there's a whole lot to learn about this field, with lots of potential for building prototypes.

That's an excellent modelling project and it looks like you're getting some great results. I hope that you'll let us know how the project flies (in more ways than one) in the end.

Joe Shockcord 06-23-2018 07:12 AM

Awesome work, "Chief Designer"! :)

JumpJet 06-23-2018 10:05 PM

Wood Fins
 
2 Attachment(s)
Today I build the wood fins for my model. All up weight for the four fins is 4.5 ounces. I still have a little more sanding to do but they are close to being done.


John Boren

JumpJet 06-24-2018 11:14 PM

4 Attachment(s)
Today I was able to finish up the wood fins and make the 40 cutouts in the main body tube for all the attachment points needed. All the parts are simply dry fitted together as seen in the photo. Currently it weighs in at 23 ounces. Also shown is the template I used to cut out all the openings in the tube.


John Boren

frognbuff 06-25-2018 06:13 AM

Quote:
Originally Posted by JumpJet
Today I build the wood fins for my model. All up weight for the four fins is 4.5 ounces. I still have a little more sanding to do but they are close to being done.


John Boren


I still wish you'd give us a tutorial on how you shape those beveled fins! You have it down to an artform!

surdumil 06-28-2018 10:47 AM

Sweet! Really nice details.

neil_w 07-20-2018 01:10 PM

Hey, do we get to see some pics of the finished model?

ghrocketman 07-20-2018 03:09 PM

What motor did you decide on for the first flight ?
Looks to be pretty draggy in addition to heavy.
I'd use a minimum of an F50.

JumpJet 07-20-2018 08:30 PM

I'm still in the primer stage of the build. I'll post pics once it is done.

As for motor choice it depends on how much it weights. It's either going to be a F26 or F50 in the center with four C6-0 for the strap on boosters. I don't need these thing to go high.


John Boren

JumpJet 07-22-2018 05:47 PM

2 Attachment(s)
I did a little more more on the model today.



John Boren

neil_w 07-23-2018 07:36 AM

I hope we get an explanation about that. It looks like the fins hook into the keyholes in the body tube... and are removable? That looks like it was a lot of effort (and very impressive), but I'm not sure what the objective was. Also I know very little about the SA-5 in general, so perhaps this is some scale-related thing that I'm just not aware of.

JumpJet 07-23-2018 09:01 AM

Just about every missile out there has bolted on fins. This means there is no neat glue fillet going along the root of the fins. I wanted to simulate that so none of the 12 fins are this model are glued in place. Now I might decide to add a couple drops of glue to the inside of the model at a couple of the screw head locations just to lock the fins in place. If I do this I may use a glue that stays rubbery, so I can still get the fins out if needed.


John Boren

neil_w 07-23-2018 09:16 AM

Ah, got it. I wish I had thought of this technique when attaching the control fins on my IRIS-T. Those rotate so there is an obvious gap where they "attach". I tried to think of ways to preserve that gap but eventually gave up and just glued and filleted them.

Very impressive work, as always.

JumpJet 07-29-2018 05:32 PM

8 Attachment(s)
My SA-5 for NARAM 60 is almost ready for paint

I learned a big lesson today. If you make two of the same parts and one of them is incorrectly made you should really throw it away so you don’t end up finishing it and gluing it to your model. In my case no one would have known it was wrong but I still had to remove it and proceed to finish the correct part which wasted several hours today. The other big lesson is, even though 3D printed parts are easy to make relatively speaking they are a real pain to finish to get read of all those layer lines. I used 8 cans of primer on this model which is crazy. Then when you’re done finishing the correct part, try not to drop it breaking off a critical part. The very bottom of this body has a specially made part that the rear of the solid rocket boosters bolts too. I bet you can guess which part broke off.
The easiest parts to finish on this model were the four large fins witch were made out of wood and one of the tunnels along the side of the body which was made of wood as well.
I still have a few more coats of primer in a few areas the body to finish but other than that she is ready for paint.
I'm pretty sure this is the color scheme I am going with. This way I don't have to worry about the thousand decals of text and such that would other wise need to be applied.

neil_w 07-29-2018 08:03 PM

Do you sand the primer on a model like that? Seems like it would be nearly impossible to do around all those little details.

Blushingmule 07-29-2018 08:34 PM

Impressive, most impressive!
 
John,

That's some nice modeling!

Bob

JumpJet 07-29-2018 09:28 PM

Lots and Lots of sanding of Primer.


John Boren

JumpJet 08-01-2018 09:13 PM

SA-5 Painted
 
4 Attachment(s)
My SA-5 for NARAM is almost complete. I just finished putting all the parts together. The four strap on boosters are held in place with small brass screws. The small fins on these boosters are also held in place with the same screws. The mid size fins at the rear simple push into a keyed slot. The main fins are currently just pushed in place and then pushed down into their key slot. I may reach in from the inside of the model and add some Aleene's Tacky Glue to the upper screw head of each fin. This should hold the fin in place but still allow them to be removed it needed. As seen in the photo it weighs in at 31 ounces. I still need to add the screw on motor retainer, Elastic Shock Cord and Large Mylar Chute that I still Need to make. I used Createx paint for the color. I think it's going to need another week to fully dry.

John Boren

mojo1986 08-01-2018 09:32 PM

Stunning!

Do you use an airbrush?

JumpJet 08-01-2018 09:38 PM

I used a iwata Eclipse airbrush to spray the paint on with.


John Boren

neil_w 08-02-2018 08:32 AM

Wow, that is an amazing piece of work. Will there be decals?

ghrocketman 08-02-2018 08:34 AM

A WEEK for the paint to dry ?
Sheesh...I don't like using paint that takes hours to dry, let alone a week.

Looks really good.
Interested to hear the flight report from NARAM and what your final power choice is.

JumpJet 08-02-2018 09:05 AM

1 Attachment(s)
When I say a week to dry that means fully cured. You can easily pick up the model the next day.

As for decals, No decals. I specifically picked a display model to replicate since it has no decals. The military version ready for flight has TONS of stencils ALL over the place. I simply didn't want to go there.

Initiator001 08-02-2018 10:50 PM

I am looking forward to seeing your model, John.

JumpJet 08-10-2018 06:15 PM

1 Attachment(s)
I flew here today. I only flew her on a single motor and even then it took me two tries to get her off the ground. The model took first in static points in Team Scale. I believe I ended up in third place because of the lack of mission points.

John Boren

burkefj 08-10-2018 07:22 PM

The model looked very very nice in person, glad it flew well

Daddyisabar 08-12-2018 06:55 PM

Congratulations on the flight. Is there a chance of taking it to a Score sport launch and putting motors in the outboards? If you do I will bring down some crazy stuff as well.

JumpJet 08-12-2018 08:15 PM

I doubt this model will ever fly again. You spend a hundred hours building something, then only fly it once but that's pretty much how all my Scale models goes. At least this one only needs a little repair before I can display it.


John Boren

ghrocketman 08-12-2018 08:39 PM

What motor did you end up using ??

JumpJet 08-12-2018 08:40 PM

F50-4

surdumil 08-15-2018 09:40 AM

Congrats, John. Super nice work on a hum-dinger of a project!

ghrocketman 08-15-2018 01:03 PM

I think you should at least fly it ONCE with the outboard cluster motors as well.

I also think that entries should get mission points if they function in a completely SCALE manner....in other words if a model of a SAM or Air-to-Air missile, one should get points if it BLOWS TO SMITHEREENS at the end of the burn/coast of the rocket motor simulating the real missile. Focus should be SCALE first, mamby-pamby-weenie safety SECOND.


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