VSOS2: Very Stand-Off Scale Scout

Attempt at a "stand-off" scale mid-power rocket of an early NASA Scout
 

Introduction:
I wanted to build something a bit more involved than just a bigger or smaller version of the EconoExpress for my next mid-power bird. While staring at the various cardboard tubes I had on my workbench, I subconsciously began to assemble a rocket very similar-looking to the early NASA Scout, a 1/30th scale kit which is available from www.truemodeler.com, and which I had seen on Essence's Model Rocketry Reviews. After getting some of the scale information from the good folks over at True Modeler, it became apparent that I wouldn't be able to do a scale replica, but I still liked the look, hence the name of the rocket.

Nose Cone:
An old BT-55 nose cone from an Estes kit from back in day that needed a bit of sanding to fit, as well as the inside of the tube.

Body Tubes:
Top tube was from a roll of wrapping cellophane: 25"x1.25"
Middle tube was from a fabric roll: 30"x2.23"
Bottom tube was a used (address isn't current though) mailing tube: 35"x3.1"
 

On the finished rocket, top tube is 21" long including transition, middle tube is 26" including transition, and bottom tube is 32".

Transitions:
Made from a $1.99 styrofoam cone from a fabric store. Reinforced them with a layer of wood glue and paper, then carefully forced the smaller of the intersecting tubes through it. If I had to do it over again, I'd just make a paper shroud.

 Motor Mount Tube:
The tubes from the wrapping cellophane make for a great motor mount, just sliced a section out of one, inserted into another and peeled off a layer of paper. Perfect fit for Econojets! Inserted a spare F20 spacer for a thrust ring.

Recovery System:
Local fabric store was having a sale on some post-Halloween fabric, picked-up some bright red lightweight nylon/polyester for $.99 a yard. Cut-out a circle via the old string-and-tack method, then reinforced the edges with a zigzag stitch. Placed 16 tabs made from duct tape, put in grommets and tied on the shroud lines. Shock cord is 3/4 braided polyester elastic, $1.75 for 5 yards. Used 4.5 feet of it from bottom section to parachute grommet, then another 9 feet to the top section. Attached to rocket by sewn loops in the shock cord with two 1/4 wooden dowels through them which are then inserted through the walls of the airframe. Dowels also serve double duty as stops for the ball of damp newspaper I use for recovery wadding.

Centering Rings
Ended up having to make five of them for this project! Ugh, nothing like carving these things out of 1/8" balsa with a utility knife. Two for the top and middle body tube joint, and three for the motor mount, since I didn't use thru-the-wall construction for this rocket. As usual, covered them with wood glue and paper. How did I join the middle and lower tubes together, and how did that work with the mid-body separation? Read on!

 Mid-Body Separation
When I first started building, wasn't sure how I was going to go about creating the separation joint. Didn't have enough mailing tube to make a coupler, and I didn't like any of the ideas I came up with using a centering ring solution from the middle tube. What I ended up doing was hacking off a 4" section of the mailing tube and permanently joining it with the middle tube. Since the diameters were somewhat close, I just slit some heavy cardboard tubing and built-it up some 1/2" in width centering rings. Yes it is heavy, but this rocket wasn't about performance, and after five centering rings, I wasn't about to do anymore. The system also gave me an idea. I had another tube which had an external diameter a bit smaller than the inside one of the mailing tube. Hacking apart my smashed 3x24mm rocket (don't ask), I had just the right amount of tubing to form a coupling, and exactly the right diameter with two layers wrapped around the smaller tube. What luck! Gluing that into the other end of the 4" section, I had myself a strong albeit heavy separation point.

Motor Retention
Since I had inserted a thrust ring, I figured I might as well make up a motor retention system other than friction fitting. Found what looked like some oversized screen door clips that did the job perfectly. Just glued in screws through the third motor centering ring (reinforced with another layer of balsa and wood glue behind mounting points), threw on the clips and then some nuts, and it works fine.

Fins:
I was worried about sections smacking together at ejection, so I wanted the fins to separate rather than crack, so no thru-body tube mounting this time. Besides, I was running out of building time and surface mounting is so much faster. 1/8 balsa stock, 20-pound paper and watered-down wood glue, that's it. Right angle triangle shape, 4" root. External paper fin mounts added after initial attachment, as well as a final wood glue fillet.

Launch Lugs:
I wasn't happy with the rather weak link of a screw eye being supported with just the body tube as on EconoExpress, and this rocket was going to be much heavier. By this point, I was really running out of time, and I was visiting friends at the time, so no big work shop. I ended up screwing the eyelets into pieces of somewhat streamlined balsa, then attached them to the rocket with wood glue.

Painting:
Paint? Who said anything about paint? SOS will probably remain unpainted, at least through the winter.
Note: I did end up throwing a layer of paint on it, since the temps have reached over 50 degrees in the Northeast in January, I couldn't pass the chance up. The middle section if you can't tell from the pictures is metallic wrapping paper with prism dinosaurs printed on it.

First Flight:
Happened to be visiting friends only about 15 minutes from CATO Rocketry's winter launch site. Hmm, wonder how that happened? Was able to get one flight off. Of course, after getting the bird onto the launch rod, I had forgotten an igniter... After inserting an igniter, realized it was from an F20 and not the G35-4 package I currently had sitting in the rocket. In other words, I didn't have much to work with. Taping the igniter in place and barely having enough room for the clips, I taped the whole mess to the motor. Crossing fingers and praying nothing would short, hold too well or drop out, I took one last look at the mess and got ready on the front-line for the flight. Waiting for the launch, I was zooming in with my camera to see if the igniter was still installed. I was a nervous wreck. Finally, the mid-power pad! First two rockets had various problems, and by this point I was getting really nervous.

The button was pushed and... WOOHOO!! The motor lit! Jim, did you sell me some 'special' Econojets to get me hooked as a buyer or what? I completely flubbed trying to take a picture. I was just staring at the rocket as it soared straight upwards at a viewable speed, yet it seemed to totally ignore the wind. Beautiful, bright exhaust plume and the noise! Ejection occurred at or very near apogee with a clean separation and without any tangles, about 800 feet up. The rocket drifted, but still well within the field. Only damage to report is a ding on one of the fins, either from some separation contact or with a very suspicious-looking rock at the landing site.

Conclusion:
I'm certainly pleased with the result. I ended up with an eye-catching rocket (at least from a distance) that stands 84" tall, flies great on an Econojet G35-4, and cost me a grand total of $4.59-not too shabby!

As of 01/10/00, it has a flown a total of three times, all on G35-4 Econojets. On the last flight, wind drove the rocket hard into the ground, burying the nose cone a few inches and cracking it a bit (easily repaired) and popped a fin off! The break was clean, and it was hanging by one of the external paper mounts. Some wood glue on the fin itself and a bit more on the paper mounts and it looked fine the next day!