Cosmodrome Rocketry - Vostok {Kit}

Contributed by Jeff Brundt

Construction Rating: starstarstarstar_borderstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar_border
Manufacturer: Cosmodrome Rocketry


[Rocket Pic]Brief:
This model is a HPR 1/35 scale model of the Vostok launcher used to put the first man, Yuri Gagarin, in orbit in 1961. The model is powered by a H242 reloadable motor and recovers in two pieces via parachutes

This kit is intended for the craftsman builder. While each step is not excessively difficult, experience with various building techniques is required to achieve a good finished model.

I ordered this kit almost a year ago directly from Cosmodrome. There were some difficulties getting the kit (Cosmodrome is a cottage type industry run out of Mike Kruger's home) but eventually it arrived. Everything was packed in a double plastic bag similar to an Estes style kit. There are a lot of parts with this kit. Almost 160 pcs. I opened the bags up and did an inventory. Everything but the shock cord was there. I didn't sweat this too much since I have plenty of elastic for other scratch build projects. And considering the ordeal I went through to get this kit I figured it was easier to provide it myself than try to call Mike and get him to send some.

The body tubes are typical kraft type tubes. They look exactly like LOC/Precision tubes. The nose cones were balsa and probably made by BMS. Centering rings are also included. They are 1/8" A/C ply and nicely cut. The fins were pre-cut 1/8" A/C ply. Decals were minimal and self-stick clear label type material with the lettering on them. These were most likely done up on a computer then printed. The wood for making the various struts and details was of good quality. (bass & balsa) There was also music wire (.040 dia) pre-cut for the various antennae details. Two parachutes were provided (24" & 35") they are rip stop nylon. They are purple in color. I could not tell who manufactured them since they did not look familiar to me. They were already assembled with shroud lines attached. There were posterboard pieces supplied as well for the various shrouds and transition sections. Patterns to make these were also included.

The instructions were several pages long with computer drawn pictures for many of the steps. The instructions were very basic. I had to read them several times through and study the pictures carefully to make sure I understood what was intended. I would not call them the best but they were adequate. This is where having built a few scratch built rockets comes in handy.

There was also a 10oz lead fishing weight provided to glue in the nose cone to achieve the proper CG. This rocket is designed to use scale fins only. There are no clear plastic fins or removable fins for flying only. The model MUST have this nose weight installed to fly stable.

I built this kit pretty much per the instructions. I will hi-light some of the things to keep in mind and some improvements I made.

Paper transitions are easy to do but they have some drawbacks. A few of them for me are finishing and durability. I decided to 'glass' the paper shrouds and transitions on this model. I used Z-poxy finishing resin and 3/4oz glass cloth. The weight gain is minimal and I fill the weave of the cloth with lite-weight spackle and sand. Ready for paint then. With this model there are six paper shrouds to make. Needless to say this is time consuming. Basically I did all the steps where I needed to make the shrouds and assemble them. I got all my parts fit and gaps/mismatches filled and sanded smooth. The secret to a good glass jod is to prepare the surface underneath. A bad prep will show through.

First, I built the strap on boosters completely and glued on the nose cones. This deviates from the instructions. They have you put the cones on last after the boosters are glued to the main body. This didn't seem right to me and makes finishing a lot harder. Once the cones were glued on and the boosters were ready I glassed them all at the same time. Then I glassed the shrouds on the main body. With all the glassing done I could fill and sand everything at once. Plus I would only have to make up one batch of resin and have less waste. Something else I did was make up details of the booster hold down devices on the main body tube. I had several scale resources and I made these pieces up from balsa and sheet styrene. They add a little bit more to the overall model and were not hard to make.

The next interesting area is the interstage truss frame. This is made up of an octagon ply ring and wood dowels. The truss is not load bearing, however. At the base of the upper payload section there is a centering ring epoxied into the end of the body tube.

The short bottom tube of the upper section, where the coupler tube is, also has a ply centering ring epoxied in place. A long shanked screw eye with a nylon spacer tube separates these two sections. This screw eye is what provides the load bearing capacity. The truss work adds a little but not much. The octagon ring is spaced from the upper body centering ring using modeler shaped balsa pieces. There are two marking guides included to mark where the truss pieces are supposed to line up to on both the upper section and the lower section. By taking your time and making sure each piece fits will insure a good looking part of the model.

The rest of the model assembles pretty straight forward after that. There are conduits that run the length of the main body but they are rectangular in cross area and made from balsa. Very easy to do. The Cross support frames at the base of the booster are made from bass wood pieces. There is a diagram in the instructions on the size and shape to make these. These should be finished separately since they will be installed after the individual pieces are painted and then assembled. There are various antennae and other details on this model. These are all made with wire and balsa. You will have to cut and shape most of these pieces yourself but there are pictures provided and all the cuts are straight with no tricky curves and such.

This model is very similar in construction technique to The Vostok in Peter Alway's 'The Art of Scale Model Rocketry'

[Close up]Finishing:
This model needs to be painted in pieces before assembly. The four strap on boosters are painted individually as is the main body and payload section. Once everything was prepped I sprayed a white primer coat and check for blemishes. When I was satisfied with that I gave all the pieces a coat of gloss white. After the white was dry I masked off for the green. I used a leaf green made by krylon. Olive drab seemed too dark. In reality the whole rocket was a green color. The white you see in pictures is actually frost from the liquid oxygen in a fully fueled rocket. After the green dried I painted the lower portion of the booster silver per the instructions.

Around the base of each booster is a silver area as well. This area on the real rocket was stainless steel to protect it from heat from the central body motors. It is actually shiny and most silver paints are dull in finish. For this area I used self adhesive mylar I purchased from a local craft store. The kit includes a painting template for this area and I used this to make my mylar pieces. They really add a nice touch.

Once everything is painted it is time for final assembly. The main body has some ply supports for the booster motors. They fit thru slots you cut in the boosters and provide good support. Also keep in mind the aft truss supports for the boosters. This truss surrounds the main body tube and needs to be assembled around it before you attach the boosters. Do not glue this trusswork at this time. It will hold together via friction fit during assembly. This will allow you ti get everything lined up. I epoxied each booster individually. I only put epoxy on the inside of the booster tubes and did not surface glue then to the main body. This is not necessary. I aligned everything carefully as I went and ended up with a straight assembly.

Construction Rating: 3 out of 5

This model needs a high power motor. You need to be Level 1 certified. The only motor recommended is an Aerotech H242-S This motor will give this rocket a quick shot off the pad and get it flying right away to keep it stable. Remember this is a heavy rocket and it has a lot of cross sectional area to push through the air. In order to run a simulation I needed to find the total cross sectional area. I summed up all the sections and found the area for a single diameter (about 6.375") I ran this on WinRoc and it gave me a projected altitude of 800' with a recommended delay of 6 seconds. The H242 is perfect for this bird.

Per the plans, motor retention on this model used a threaded rod epoxied to the side of the motor tube. After motor installation place a washer and nut on and you are done. This method is adequate and works well. However, I prefer another set up using API's motor retainer. I admit they are pricey but they are slick and easy to install and use. Just bond the threaded base to the exposed part of the motor tube. Install your motor, screw on the cap and you are done.

I also ran this model through a descent rate calculator. The 24" 'chute provided for the payload section was fine. However, the 35" 'chute for the booster was marginal at best. The descent rate was much higher than I liked to insure a damage free recovery. I opted instead to use a 54" TopFlite parachute for the booster. Stuffing this 'chute though would require creative packing. The body tube for the parachutes is not all that big. You really need to know how to pack your chutes right to insure a good recovery with this rocket. For wadding I used shredded paper insulation. No problems her. I just got some Nomex® cloth 'chute protectors and will be using these in the future.

First flight day was overcast but no wind. Not ideal but not bad either. The no wind was perfect. At motor ignition the rocket leapt off the pad like a shot. No slow lift off here. I boosted straight with no spin or wobble. I arced over and was at a flat trajectory when the ejection charge went off and both chutes deployed perfectly. The two pieces drifted down gently and recovered with no damage.

Flight Rating: 5 out of 5

Summary :
I have flown this rocket several times now. It is always a crowd pleaser. I get many questions and good comments about the rocket.

Some PROs for this kit:

  • Level of detail
  • Impressive size on or off the pad
  • Good flight characteristics
  • Quality materials in kit

Some CONs:

  • Weight
  • Main parachute too small
  • Lack of detail in instructions

Overall I was very pleased with this kit. It is a nice sized model with just the right amount of detail. Granted I did a few extra things but this kit really is intended for those who have some experience beyond even an Estes level 4 kit. If you are a HPR modeler and would like the challenge of a scale kit, this might be the one for you.

Overall Rating: 4 out of 5

Great review! I really like being able to point people to places that give help with this kit. Two clarifications: 1) the nose cones were not made by BMS, I make all my cones myself. 2) the parachutes were also made by myself (or my wife). As with my other kits, the instructions are being updated for clarity and simplification (and in the case of the Vostok, some corrections). - Mike Kruger (Cosmodrome Rocketry)



K.B. (January 1, 2000)
I love this kit .. only modifications I would have are: 1. Explicit provision for recovery avionics. 2. More room for parachute and recovery harness. 3. Fiberglassing shrouds is a great idea since shroud damage seems to occur on every flight. Great review! Accurately reflects my experience with the kit. I built mine relatively stock with minor modifications to fly with recovery avionics (blacksky AltAcc) and single parachute harness. This model is impressive on the launch line (many comments) and surprisingly good flier and robust recovery. I've flown on I161 with great results and will likely try higher power. Since my only complaint/problem seems to be shroud damage on otherwise normal recovery, I would advise any prospective flier to use the technique in this review and lightly 'glass the shrouds.
J.A.L. (January 1, 2000)
This was an excellent (and accurate) review. I am building this kit and am adding a few things also. The biggest addition is the use of an altimeter. Believe me there is not much extra space for an altimeter bay but I made it fit, just hope it will work properly. I wish that the CP was indicated on the instructions though. I can do a CP calculation for as straight forward design but for something this unique. I think I would go mad before I found it! (not to good at higher Math)

comment Post a Comment