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Soyuz build from Cosmodrome Vostok

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delta22

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The Vostok kit by Cosmodrome Rocketry is a beautiful 1/33 scale flying model of a very cool looking and historic rocket.

Last spring at NARCON Cosmodrome had this kit available for the first time in a couple years and I bought one immediately.

The rocket is 45 inches tall and designed to fly on an H242. It is a very complex build due to the complex shape of the original rocket.

The kit has 5 balsa nose cones, 2 parachutes, and many tube sections, shrouds, balsa and basswood pieces plus other parts. Instructions, like the kit are intended for a skilled builder willing to invest time in the project.

All parts necessary to build the rocket are included with the kit, as shown in the picture.

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delta22

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Planning three modifications to the Vostok kit build:

1) As a big fan of cluster flights, will add 4x 24mm motor mounts in each booster, matching the motor layout in the real rocket's boosters. Keeping the kit's central 38mm mount.

2) Building the rocket as a Soyuz instead of a Vostok. This only requires modification of the upper section. Doing this because
> the Soyuz is very recognizable and cool looking
> allows for a scale 3 or 4 color paint job
> is longer than the Vostok, which facilitates achieving stability and mod 3).

3) Altimeter dual deploy. Hope to create an altimeter bay above the 2nd to 3rd stage transition structure.
 

delta22

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Started by building the boosters, as I am still working out core mod options.

These shrouds are a different shape than the saucer or nose cone shrouds I have done before and were challenging. There had also been a glitch at the copy center when the kit's booster template was produced, so I had to reduce the size of the template to 94% to get the shroud to fit.

Ended up making 3 variations on the template shroud, then attempting to form 6 shrouds from this before I had 4 I was satisfied with. Initially I had doubts I was going to get there, but the last 2 shrouds came together much more easily.

Glassed the shrouds with 2 layers of 1.3 oz FG and West 206 slow epoxy to harden them up. While the FG was wet, cut the glass 1/4" past transition points.

Modified assembly process to make room for addition of booster motor mounts not yet completed.

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sandman

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Boris, let me know if you need documentation.

I have lots!
 

delta22

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Boris, let me know if you need documentation.

I have lots!
Thanks for the offer.

I have the NARTS CD loaded with information on Russian rockets, including the Soyuz, Vostok and others.

Been carefully examining the detailed engineering drawings by Vladimir Minakov and converting to scale for the Soyuz mod.
 

sandman

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Thanks for the offer.

I have the NARTS CD loaded with information on Russian rockets, including the Soyuz, Vostok and others.

Been carefully examining the detailed engineering drawings by Vladimir Minakov and converting to scale for the Soyuz mod.
Great, I may ask you for some info!:wink:
 

nh4clo4

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Awesome project! Can't wait to see the rest of this build.

:pop:
 

sodmeister

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Awesome project! Can't wait to see the rest of this build.

:pop:
That makes two of us !!! I finally bought (or rather snapped one up) last spring when they became available.....almost a dream come true.

I have this bookmarked.....thankyou !

Paul
 

mperdue

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FWIW, a similar project can be found in my book. It includes the Soyuz and Luna nosecones. This is a really fun build. I'm looking forward to seeing how much detail is added here.
 

Sandy H.

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What!?!?! I figured you'd just put a single 54mm mount in the core instead of going through all of that clustering effort. I mean, who flies clusters anyway. . . :lol:

All kidding aside, when was the last time you flew a rocket with one motor?

Looking forward to pictures!

Sandy.
 

delta22

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A couple plugs for vendors providing essential elements for this project.

> The Cosmodrome Rocketry website states that more Vostok kits will be available soon.

They also have a number of other nice scale kits, mostly mid-power, like the Black Brandt and Nike Apache. http://www.cosmodromerocketry.com/

> Earlier I mentioned the NARTS CDs of rocket data. NAR Technical Services offers 3 CDs at $29.95 each that have 100s of pictures plus engineering drawings of dozens of historic rockets.

They are a real treasure trove for a scale model rocket builder. https://blastzone.com/nar/narts/store.asp?groupid=92400111757284
 

delta22

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The booster shroud was still quite flexible with 2.6oz total FG. Also the cardboard bottom of the booster concerned me, as I could picture it taking damage both during recovery and transport.

To further tighten and harden the boosters, covered them from top to bottom with 2x layers of 1.3oz fiberglass. This made 2x layers on the balsa nose cones and cardboard tubes and 4x layers on the paper shrouds.

To lay the glass cleanly over two transition points, I started in the middle and rolled it flat top to bottom. Then worked out to each side always going from top to bottom to keep the transition bends tight. When the glass got to the far side from the starting point, then did a final trim to the glass. This seam point will be where each booster joins to the core. The first booster required a lot of clean up sanding, the last three boosters were done more cleanly to start with.

End result felt much tougher. Even though the shrouds are still moderately flexible when squeezed, they do not feel like they will be easily damaged. Boosters were 3.7oz each before fiberglassing, 5.7oz after.

As 4x D motors weigh about 6oz, and this weight will be at the tail of the rocket, much more nose weight will need to be added to balance the motors than the light fiberglass shell.

On several other projects, mostly based on LOC cardboard tubes, 2x layers of very light fiberglass seems to go a long way for durability. Modest gain in overall strength but a big gain in surface hardness.

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delta22

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After fiberglassing the boosters, sanded the NC tips and painted with epoxy for the second time. This time hanging boosters upside down so flow of epoxy helped to form nice tip.

Also made new fins using same scale fin size with 5 layer plywood as came with kit. Fin modification has larger tabs to connect to 4x motor units. Put one layer of 1.3oz FG on fins mostly to smooth and harden surface.

In the second picture, can see light shining through the boosters. Paper and 4x 1.3oz FG is pretty translucent after being impregnated with resin, even with a tube in the middle.

Pictured motor units are 4x 24mm LOC tubing.

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delta22

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Cut a slot in each booster to receive its fin. Had shortened the internal tube and left off lower centering ring to make room for motor units.

Another option for a builder of this kit would be to put one 29mm motor mount in each booster's central 38mm tube.

Epoxied in 4x motor units and fins. Rings shown on the side will reinforce bottom edge of boosters.

Painted: (why)
> West 206 epoxy where motor units join boosters and tops of motor tubes (bond strength and fire hardening)
> Thinned (20-25% alcohol by weight) epoxy on all exposed tubes in tail (fire and water protection)
> more epoxy to secure rings at bottom of boosters (impact hardening)

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Spurkey

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Amazing-looking build already, I can't wait to see how this turns out. I was lucky enough to snag one of these kits as well and have gotten stalled on the booster shrouds, specifically on strengthening them. I have a couple of questions, hope you don't mind.

1) When you say:
Glassed the shrouds with 2 layers of 1.3 oz FG and West 206 slow epoxy to harden them up. While the FG was wet, cut the glass 1/4" past transition points.
What did you use to cut the wet fiberglass? I've had a really hard time cutting FG cloth with an Xacto knife, it always frays on me. I'm pretty concerned that if I try it wet then I'll make a colossal mess of frayed ends only to have it set up on me. :( I don't have a lot of experience with FG, any advice would be appreciated.

2) Did you consider applying FG to the insides of the shrouds? Mario mentions doing so in "Seize the Sky", to me that seems like a good way of hiding the seam where the FG ends.

3) On the 24mm motor mounts I didn't see any place that vents the ejection charges - are you planning on using plugged motors? Or just letting the spent motors blow themselves out the back?

Thanks!
 

delta22

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Amazing-looking build already, I can't wait to see how this turns out. I was lucky enough to snag one of these kits as well and have gotten stalled on the booster shrouds, specifically on strengthening them. I have a couple of questions, hope you don't mind.

1) What did you use to cut the wet fiberglass?

2) Did you consider applying FG to the insides of the shrouds?

3) On the 24mm motor mounts I didn't see any place that vents the ejection charges - are you planning on using plugged motors?
Thanks!
Thanks. I started with the boosters because I was still deciding some of the details on the core of the rocket, but in many ways the boosters are a tricky build.

1) Knowing that I was going to fiberglass the shrouds, I used thinner paper than what was supplied. Also had to reduce the kit template to 94% for a tight fit around center tubes.

To avoid adding too much weight, I use a few layers of very thin, light fiberglass. The 1.3oz mentioned means that one square yard of this fiberglass would weigh 1.3oz. When folks are building for high strength, using several layers of 6 or 8 oz fiberglass is common, which is much more thick and coarse. 1 to 2 oz fiberglass handles like silk fabric, 6 to 8+ oz is more like canvas.

The thinner fiberglass cuts easily and cleanly with sharp scissors when dry. After wetting with resin, it cuts easily and cleanly with either scissors or a sharp Exacto.

There is no need for heavy fiberglass on a rocket like this that will not travel at extreme speeds. The thinner fiberglass becomes pretty strong when built up to 2-4 layers. I will usually apply all the layers at the same time.

2) I have used fiberglass inside of shrouds in Applewhite Saucers per instructions, and because I liked the result so much in a couple custom builds of a Sirius Rocketry Saturn V and a scratch Thunderbird (TRF builds threads exist on both builds including pictures of internal FG).

Did not do internal FG on these shrouds because I wanted to reinforce them past the end of the shroud onto the adjoining tubes, and external FG was the only way I could do this.

For all external FG work I use West 206 slow epoxy. There are other good brands, but slow, thin epoxy is essential for good FG work. I also use disposable rollers ($2 at Lowes) which is much easier than brushes.

Try fiberglassing some scrap tubes first to build experience. Only when you like your results try to do these shrouds. I've made 10-20 shrouds and fiberglassed at least 50 different parts previously and found making these boosters the most challenging yet.

3) Yes, planning on plugged motors for the outboards. D11-Ps, bought a bunch last year.
 

Spurkey

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Awesome, thanks for the reply! How did you keep the ends of the cloth from fraying? I've fibreglassed "normal" tubes before and had the cloth extend past the end of the tube, then cut the excess off when dry. I always had problems though with the cloth seam that runs the length of the tube fraying, no matter how careful I was when rolling on the epoxy. With these boosters having *all* the cloth edges terminate on the surface, I definitely need to correct something in my technique. :)

Also, with you extending the FG onto the booster cone and down onto the booster base, did you have problems with the cloth wrinkling at the transitions to the different radii?
 

delta22

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How did you keep the ends of the cloth from fraying?

Also, with you extending the FG onto the booster cone and down onto the booster base, did you have problems with the cloth wrinkling at the transitions to the different radii?
PLEASE do yourself a huge favor and practice fiberglassing on scrap pieces first. Get comfortable with using slow, thin epoxy, rollers and thin (1 to 2oz) fiberglass. I used all the experience and patience I could muster to make these transitions and very nearly failed. I made 7 paper transitions to get 4 I could live with. The last two boosters I made look better than the first two.

The light (1 to 2oz) fiberglass leaves a very fine edge that can be sanded smooth cleanly with 220 sandpaper. One advantage of multiple layers of thin FG is that top layers mask edges of bottom layers, also is stronger than one heavier layer.

Be careful not to sand all the way through the thin FG. I also find using an Exacto a good way to trim thin FG, either by cutting, scraping or shaving.

Please use respirator and good ventilation when applying and sanding FG. Also gloves when applying, I get the 50 pack of nitrile gloves at hardware store.

With regard to seams on the boosters, that is the natural place to plan to epoxy the boosters to the core. So if they are still imperfect after cleanup, they will be invisible. Planning this, I made all FG seams within 1/4" of paper transition seam.

The 2 layers of FG on the whole boosters was tricky. Steps:
1) Do one booster at a time, supporting it internally with a pole or dowel so entire outside can be wet. I did mine before adding fins.
2) Started with 2 sheets of 1.3oz FG precut to 24" x 11"
3) rolled resin over entire outside of booster
4) orient booster with paper transition seam downwards
5) lay FG on top of booster from top to bottom, starting with a narrow strip of contact in the > middle < of the sheet of FG
6) Use roller to work the FG into the resin from top to bottom, gradually working around the booster. The thin FG will shift its form by shifting its weave as you go around. Really work it with the roller and take your time.
7) use sharp scissors to cut excess FG so that each side slightly overlaps paper seam
8) immediately repeat process with second layer of FG

If you find the resin is setting up before you get the second layer on, mix a fresh batch of epoxy for the next layer. Never try to use epoxy that is curing (thickening) to apply FG as the fabric will not soak it up well.
 

sandman

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Boris, you sound very much like you know what you are doing.

The thing with fiberglass/epoxy is...it's messy and there just ain't no neat way to do it.

No matter how particular and fussy you are.
 

troj

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This is looking really nice, Boris!

Thinned (20-25% alcohol by weight) epoxy on all exposed tubes in tail (fire and water protection)
Just wanted to point out that the Americans did the water landings -- the Soviets land on land.... :D

(Sorry, it just had to be said)

-Kevin
 

sodmeister

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Great work ! This all very,very useful information to me and my future build.

Keep it comming !

Cheers

paul
 

delta22

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Sandman/Gordon, thanks, that means a lot coming from the number one go-to guy for custom rocketry parts.

Troj, I'll definitely try to follow the Russian example and recover the rocket on dry land...but just in case...

Paul, (Great name, that's what we named our son) glad this info is useful to you, please feel free to post if any questions.
 
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delta22

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Started the lower core build by sanding and wrapping both tubes with a double wrap of 1.3oz FG.

As the tubes were very slightly larger due to FG, sanded the inside of the 3 centering rings with a 54mm tube wrapped with 220 sandpaper.

Had difficulty getting supplied shroud templates to fit, so used Body Tube Transition Creator at EMRR: http://www.rocketreviews.com/tools.shtml

For bottom core shroud used
small ID: 2.46
large ID:3.60
length: 5.44

For top core shroud used
small ID: 3.08
large ID: 3.60
length: 6.05

For both shrouds made shroud 3/8" long (around) and then trimmed to fit. Then sanded seam.

Used same approach as with boosters to cover shrouds with 4 layers of 1.3oz FG.

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Stymye

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enough can't be said about those little foam rollers for epoxy work.They conform to curves and fillets,
leave the perfect wetout of epoxy, and make the job so easy.I use them whenever possible


 
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delta22

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Lightly sanded and painted the fins and the area where they join the boosters with thin, slow epoxy twice. Also painted the inside fin joint with the same West 206 epoxy. Forming smooth surfaces and light, strong joints.

With the current cold weather, even in my basement with a space heater, it takes days for this epoxy to cure between steps.

Then took four 5/16 turnbuckles and:
> removed the screw eyes
> cut off the left threaded half of the pictured aluminum center piece
> wiped with alcohol and then abraded surface with a rough file
> lubricated a 10-24 screw with oil (so it can't be accidentally epoxied in place) and put it in the aluminum piece
> put a small piece of masking tape over inside hole on aluminum piece to prevent entry of epoxy to center hole
> and finally epoxied threaded aluminum pieces in the center of each cluster of 4 motors

These are a perfect fit between 4x 24mm tubes. I have used these many times for motor retention anywhere I don't want a protruding threaded shaft. They receive a 10-24 screw.

Two follow up additions of tiny amounts of epoxy plus sanding created a uniform surface.

Total weight addition of 4x aluminum pieces, 4x 1" screws and washers is slightly over one ounce.

Also wrapped the central core with sandpaper and sanded the boosters where they will later be joined. Did this both to create rougher surface and to flatten a few uneven spots for tighter bonding later.

Primary build of boosters is finally done. Painting and final bonding to central core will come later.

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delta22

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Picked up an Aero Pack 38mm retainer and 29mm to 38mm adapter. Light weight and well made anodized aluminum parts. Expensive but well crafted.

> painted the inside of the 38mm motor tube with thinned epoxy and sanded it once cured
> bonded Aero Pack retainer to motor tube using the recommended JB Weld epoxy
> epoxied and filleted 2x centering rings to motor tube
> epoxied this assembly into the core and filleted

Set motor assembly just far enough into core that retainer does not protrude. Confirmed prior to gluing that retention cap can be screwed on and off in the available space.

Painted outside of core assembly with epoxy and sanded to fill and smooth the hardened surface.

Painted the inside of the core with thinned epoxy and sanded twice to fire harden against ejection charges.

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sodmeister

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Right on Boris ,good to see you are back at it !!

I was getting worried for awhile.Would have been a sad day if this thread should have stopped here !

Bravo !!


Paul T
 

delta22

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Right on Boris ,good to see you are back at it !!

I was getting worried for awhile.Would have been a sad day if this thread should have stopped here !

Bravo !!


Paul T
Thanks. I figure that with about 60-80 hours into the build so far, it is about halfway done. Will definitely complete this and fly it this spring. I will not start any other complex project until this flies.

With slow epoxy curing and project planning and complexity this build will take months to complete.

There was a beautiful Soyuz pictured flying in the latest Sport Rocketry.

A number of websites have interesting information on the Soyuz including this one:
http://www.spacelaunchreport.com/soyuz.html

I already have the motors for the Soyuz' first flight:
1x ProX 29mm 3grain G125 Red
16x Estes D11-P

total impulse: 477 Ns
average thrust: 301 N
= I-301

Estimating flight weight around 8lbs, including 2lbs of motors and 1+lb nose weight. Nose weight will be dialed in when I can weight the completed rocket and more accurately model it.
 

sodmeister

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Indeed ,not the kind of kit that builds on a weekend ,not to mention the mods you are making.

Going to be a heck of a first flight.Hope you gets pics & video.

Cheers

Paul T
 
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