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

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.


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