Plastic Kit Convair ISX-SSC

Contributed by Geoffrey Kerbel

(by Geoffrey Kerbel - 12/10/06) (PMC) Revell Convair

Brief:
This is a plastic model conversion of the Revell Authentic Kit of the Convair ISX-SSC model. This was an eBay buy from earlier in the year and is the 1996 issue of the kit. This comes up on eBay quite often and can usually be won for a small, reasonable price. The original came out in 1959. Those are going for some outrageous amounts and you would not like to mess up that kit with this conversion. I remember assembling it as a kid myself. I had got it as a childhood reminder, but months later after inspecting the kit, I found an important part missing and just stashed the model away. I was going to attempt a F-104 conversion but could not figure out just how to do it. While searching for something else, I came upon this kit again and realized that it would make an excellent model to convert to flying status for the EMRR 2006 Challenge.

Construction:
The kit itself is a very basic build with several sections that would come apart on the display model but will be glued together to fly. The lower booster section is an excellent piece for the addition of a 18mm body tube/motor mount with the upper stages fastened together to form the nose cone. This would allow for plenty of power for flight with a small, fairly heavy rocket. For this conversion, you will need the following:

  • All of the first stage parts
  • All of the second stage parts
  • All of the third stage parts (mine was missing the third stage engine unit bulkhead)
  • All of the Glider Unit except the cabin bottom, cabin top and crew figures
  • One BT-20 tube, 5 1/16" in length
  • One BT-20 coupler tube, 1 7/8" in length
  • Two CR-2050 rings (the thick green ones)
  • One CR-520 for a motor block
  • 6" of 70# Kevlar® for shock cord mount
  • 24" of 1/8 elastic for the shock cord
  • Launch lug, 1/8" x 1"
  • One 10" to 12" chute (keep it thin, AKA Estes)
  • Some extra clear, stiff plastic for two add on fins
  • Thin and thick CA, 5-minute epoxy, and some plastic glue

Construction starts with the first stage booster parts. Take the upper and lower bulkheads and add one 2050 centering ring to each one. Make sure you add the rings to the side that goes into the booster body on both bulkheads. The rings should easily center into the bulkheads by eye. Use some thick CA on the ring edge and place into the bulkhead end. When the CA has set up, use a drill or knife to open up the plastic on the inside of the rings. Take out just enough for the body tube to fit in snuggly. The upper bulkhead will be easy to do but the lower one will take some work. Try to open it up without completely destroying the engine nozzles. If you are careful, most of the outboard nozzles will be left for show. Test fit the fuselage parts together with the bulkheads. Trim the plastic as necessary for a good fit. The parts on mine fit well enough that they stayed together without glue. Test fit the BT-20 tube into the fuselage. The bottom end should be flush with the bottom of the bulkhead resting on a flat surface and the top should be flush with the top bulkhead or just slightly below it. If everything fits well, use a good plastic cement or thin CA to put the first stage booster together. Do not glue the BT-20 in at this time.

Take a used 18mm motor and wrap some ¼" masking tape around the nozzle end just as if you were going to use it for flight. Test fit the motor block slightly into the BT-20 tube and if OK, pull it out and add some wood glue to the inside of the BT-20 about 1.5" in. Insert the motor block and using the old motor as a spacer and push the block into the tube in one continuous motion till the tape stops it. Pull the motor out right away and let the glue set up. Don't stop or do this slowly or the motor block will "grab" and not be far enough in to take the motor. Once this has set up, measure down from the top of the tube to the motor block and transfer this measurement to the outside. Make a very small hole at the mark, which should now be just above the motor block inside. Use some thin CA to harden a very short part of the Kevlar® (1/8" or less) and insert it into the hole from the outside. Feed it through and out the top of the body tube. Take that end and make a small loop in the Kevlar® for the later addition of the elastic shock cord. Pull the Kevlar® back inside of the tube till the loop is just inside the tube. Take a small piece of masking tape to tape the Kevlar® to the outside of the body tube at the other end. Make this a flat as you can. Use some thin CA to hold all of this in place. When dry, cut off any excess Kevlar® and set it aside.

Using the fins on the first stage as a guide, make an outline of the shape onto some paper and transfer that outline to the clear plastic. You will need to make two more fins out of this to aid the stability of the rocket for flight. Without the extra fins, the rocket would have all of its fins in one plane and would tend to take off straight and then most likely go horizontal and try to fly like an airplane. No use feeding the rocket gods right away in you can help it! Once you have the extra fins cut out and smoothed the edges, you will need to mark the first stage fuselage for them. Keep the new fins centered between the original ones so that you will have a standard four-fin rocket when they are attached. Keep these new fins flush with the bottom of the rocket so it will be able to stand on its own as well. I roughed up the area on the fuselage where the new fins would go to give the glue some extra bite. Use some thin CA to tack them on and finish with some 5-minute epoxy for the fillets. Take it easy with all of the glue on the lower part of this rocket, it is heavy enough as is.

Add a 1/8" x 1" long launch lug to the fuselage about ½" down from the top. Keep it on the round side of the fuselage and just clear of the added fin.

The most difficult part of the conversion is next. The second, third and glider stages need to be modified to form the nose cone. This took me the most time and was done "on the fly" with many "look see" sessions before actually cutting anything. I had no spare parts in case a mistake was made! For this kit, I had to make a third stage lower bulkhead, which was the missing part I discovered earlier. It is the white plastic piece in the pictures. Once that was done, I needed to add the coupler tube to the parts which was to become the nose cone shoulder. After careful consideration, I had a plan!

Take the second stage parts and assemble them per the model instructions. Do the same with the glider section but leave the interior parts out. Glue the canopy to the glider instead of leaving it loose. Add the third stage engine unit bulkhead (the piece I had to make) to the third stage fuselage bottom but don't glue the third stage plate on yet.

Test fit all of the upper stages together now and adjust as necessary so they can all be glued together later. They will all be needed together as well to help in fitting the coupler into the second stage so that they will be straight and true with the first stage.

Take the BT-20 tube and reinstall it into the first stage booster. You may have to notch the lower CR slightly to pass the Kevlar® bump on the outside through. Once in place, take the coupler tube and insert it into the top of the BT-20 about 1/3 of the way in. This will be your guide for notching the second stage booster to fit. Keep the locating pins on the second stage for now and using a knife or round sanding block, slowly start taking material out of the bottom (flat) side of the second stage. Open up both of the end pieces to fit the coupler tube. Keep checking the fit to the first stage as you go and stop when the coupler fits into the second stage and the second stage fits flat onto the top of the first stage with the pins in place. The glider section on top of the second stage booster is used to form the upper stop of the coupler.

The third stage lower bulkhead will have to be opened up the same way so that the third stage will fit flush with the other two stages and the first stage body when assembled with the tube coupler in place.

Use the third stage and glider section as necessary to keep all the pieces aligned with the first stage. If the coupler is fitted at an angle, the nose cone will not be straight to the first stage. You will be taking all three pieces and fitting them together and taking them apart many, many times! But in the end the nose section of the new rocket will be a nice fit. The notch doesn't have to be very pretty because when completed, it will be out of sight except when the two pieces are apart for recovery.

The flat piece for the third stage has to be notched for the coupler as well and don't just open it up to the coupler diameter. It actually fits slightly to one side. You could just cut it off at the bottom to clear the coupler but the extra material on either side of the coupler gives you some extra surface to hold the whole thing together.

The glider piece is the only section that needs no modifications for the tube coupler.

Once you are satisfied with the fit of all the pieces and the tube coupler to each other, remove the coupler and using the centerpiece from a CR-2050, glue this to form a cap onto the coupler to seal one end. You can use some extra glue when working on the nose cone parts to add some extra weight to the upper part of the rocket for stability. I used 5-minute epoxy on most of this assembly.

Final assembly can now be started. First cut a small slit into the cap and feed the shock cord through until about ½" is left outside. Fold this over onto the coupler and epoxy it to the coupler. This will secure the cord to the nose cone. Glue the second stage booster and glider section together using the third stage to keep them flat with each other. Do not glue the third stage to the other stages yet! Once set up, remove the third stage pieces and glue the coupler into the second stage so it is up against the bottom of the glider section. Use glue only on the inside of the second stage to hold the coupler in and make sure the shock cord "bump" is facing out. Add the third stage flat piece to this next and add any additional fillets as needed now. Keep the third stage half round piece loose for the time being. When dry, attach the other end of the shock cord to the Kevlar® and test fit the whole assembly together. The coupler piece should be a snug fit but loose enough to eject. Adjust as necessary.

Attach the chute to the shock cord a few inches down from the nose cone. You will have to set this point by trial and error. Pick a spot on the shock cord to attach the chute, pack the whole thing up and blow the nose cone off. When the chute comes out as it should, you have the proper spot. You may have to pack the chute into the coupler and the shock cord into the main body or vice versa. There is not enough room to pack the whole thing into the body tube.

Put the whole thing together again and load an engine as well. Using some string, find the balance point. It should be about 3.5" up from the bottom. Wherever yours is, tape it in place and do a swing test. Add clay to the loose third stage piece if needed to allow the rocket to swing forward properly. When the rocket is balanced properly, finish the assembly by gluing the third stage piece to the others. My rocket did not need any extra weight for stability.

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(PMC) Revell Convair (PMC) Revell Convair (PMC) Revell Convair
(PMC) Revell Convair (PMC) Revell Convair (PMC) Revell Convair
(PMC) Revell Convair (PMC) Revell Convair (PMC) Revell Convair
(PMC) Revell Convair (PMC) Revell Convair (PMC) Revell Convair
(PMC) Revell Convair

Finishing:
I have not painted or added my decals. To tell the truth, I am at a loss as to what, if any, color to use. I was thinking along the lines of a silver rocket with standard Space Shuttle colors for the glider section. However, being as this is an old rendition of the shuttle we have today, I am also trying to come up with a retro style paint scheme. Whatever you decide to do, make sure you use model paint for plastic from a hobby shop. The automotive and Krylon type of paints will eat up the plastic because of their "hot" solvents.

(PMC) Revell Convair

Flight and Recovery:
I was able to get three flights in at our last club launch with different engines. Preparation of this one is tedious at best due to the tight constraints of the small tubes. I used tweezers to help load the shock cord and shroud lines. Very little wadding will fit but try to get at least two sheets in. A 10" diameter chute was used with lots of powder to make it as slippery as can be.

The first flight was with an Estes B6-2 engine, thinking the short delay would be needed in case of any trouble. To help with the lack of wadding in the body tube, I added one sheet into the open area at the top of each motor that was used. Actually, the rocket shot off of the pad, giving me no liftoff shot and reached about 300'! The ejection was a tad early and although the nose separated, the chute was not out. The whole thing came in fairly flat and bounced at least a foot back up when it hit the ground! Close inspection revealed no damage luckily and it was prepped for the next shot.

Thinking I was going to have more problems with that chute, I loaded up a Quest A6-4 next. The rocket again shot quickly off the pad and got about 50 to 75' up when the whole thing went unstable. That was a big surprise and it landed hard but flat. The ejection charge then went off which appeared to pull the chute out. It appeared to go unstable just after motor burnout. The chute came out this time but it obviously didn't amount to much! I think the rocket just didn't have enough forward velocity at burnout to remain stable for flight. It didn't get very high and in retrospect, didn't appear to be moving too fast as well.

Hoping the third time to be the charm, it was loaded up with a B6-4. I wanted to try a C engine but was afraid it would be too much power and get too high. If the chute again failed to deploy, I didn't want it to shatter on impact. This time the flight was stable and ejection occurred just after apogee. The chute came out but now decided to not open! Down it came, slower this time but just as hard as the first. That was it for the day as one of the added on fins completely popped off at the attachment point. It was repaired later with no other problems.

So far no really successful flights, as far as all the systems working, but it has turned out to be a very strong and resilient build to this point. With any luck I will have a completely working flight before it shatters from another bad one.

Summary:
This was a bit of a challenge to construct for the conversion but the kit itself lends itself very well to do this. It is stable with enough power and the 18mm motor mount allows this. Although the finished model is small, there was ample room for a nice size motor mount.

PROs: Easy model build with a conversion challenge that is well within the average modelers skills. Simple rocket lines with old school design without pesky details just asking to be broken off on the first bad landing! It displays nicely on the shelf as well.

CONs: Tricky addition of the nose cone shoulder. Very small model, easy to lose with too much power. No usable paint scheme to finish kit.

This was a fun project that allowed me to use a possible junk kit do to missing parts and turn it into a flying model rocket that many people were interested in when it was brought to the RSO table. It also strengthened my adage that almost anything can be made into a rocket and fly!

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