Building the DEFCON 1
This DEFCON 1 is a kit that appealed to me. I saw it on Apogee's website, it's aqua color and detailed decals made it stand out to me. The size of the rocket and motor were just in line with what I was looking for, something a large enough to be noticed both on the launch pad and in the air, and it can run on smaller B, C motors but can also take D and E black powder or composite motors. I didn't realize it at the time, but apparently this company Quazar or Quazar One went out of business and what I ordered appeared to be the last kit in stock.
This model is 39 - 1/2 inches tall, uses 24mm motor mount for D12 and E9 (and now E12) motors, and the fins are raised about two inches from the rear. They are shaped in a triangular fashion and will not protrude far and likely will not be damaged upon landing. The balsa is extra thick on these three fins, and there is a decal sized exactly to cover each side of the fin. It has a plastic nose cone that is somewhat unique. It has parachute recovery. Large decals cover the entire bod, all the paint that is needed is white, and silver for the nose cone if you follow their design scheme.
It appears to be pretty rare, as I have never found either a review or a launch log with this model. I like having something unique that nobody else has!
It is constructed with a single 34" body tube, BT-55, so of course it was crushed in shipping. They immediately sent me a new tube but told me it was the last one. Naturally they packed it to guarantee it would also be crushed, by re-inforcing the long skinny tube with thick cardboard on each end and leaving a gap in the middle of the tube. The long thin shipping carton of course was bent, so all the forces on the tube were concentrated on the un-reinforced center of the tube where it folded just as planned. Complaints got me nowhere because they had no more tubes left. A detailed sketch of the problem and solution was sent to Apogee - thinking a rocket engineer would understand it - but it was pretty much dismissed and ignored.
These tubes were pretty decent quality, as well as the rest of the kit. The details I'll describe as I build it. It's not like you need those details now, as you can't get this kit anyway. I did have two crushed BT-55 tubes. One was folded about 4 to 5 inches down, the other about 10 to 13 inches down in a wide crush zone. I cut out the damaged parts of the two tubes and figured to make one good tube from that. I wanted to make a few mods to the body tube. First, I wanted a payload bay, large enough to take an altimeter and also to be useable as a mini camera carrier, so I was looking at at least a 7" payload section. Second, I wanted to add an ejection baffle which would also act as a mount for a Kevlar shock cord. I thought I could combine the body tube coupler with the ejection baffle. Since this kit has three large wrap-around body decals, instead of having to cut the decals, I planned to seperate the tubes exactly in line with the decals. This left me with an extra large payload section. Since the length of the rocket is 1 meter, I didn't have a problem finding space for the parachute in the remaining body tube. I used a 10 inch section of the original tube, and a 24 inch section from the replacement tube to get the original 34 inch tube length. The original length was necessary to prevent trouble fitting the full-body wrap decal sheets. This works fine for the payload size, but adding the bulkhead exactly were I needed to splice the tubes meant that I didn't need a coupler at all, but it also meant that I would have some difficulty gluing the ejection baffle and Kevlar support far down into the body tube. I will choose that difficulty over making another cut half way down the lower tube just to insert the baffle.
EJECTION BAFFLE, SHOCK CORD MOUNT, BULKHEAD PREP
Construction started with me sanding a BT-55 balsa blockhead to size to fit the body tubes. I also began the process of building an ejection baffle. The basic kit I got from Uncle Mikes Rocket shack was good, but using one of these in my Estes Interceptor with a composite Apogee motor just didn't prevent the motor from buring a large hole in my nylon parachute, so I am going to add extra baffle twists and turns on this rocket which will also use large engines. I started by gluing a small section of 13mm engine tube to the upper baffle (which has holes around the outside perimeter of the baffle). When this is combined with the lower baffle (holes in the center), you will not be able to see a line-of-sight through the baffle. Without this added piece, a burning particle could bounce off the lower tube wall and go straight through the baffle at an angle. With the tube added, that pesky particle will have to make a sharp left followed by a sharp right to get through the next baffle hole. On top of those two baffles, I am adding another plywood circle with the hole in the center again, so those particles will have to make yet another turn back in the opposite direction. I want to be careful though not to make it too difficult for air to pass through, or I could just end up with a lower tube bursting from the pressure! When all the baffle gluing is finished, I am going to spray paint it from the engines point-of-view with a special high-temperature silver paint to help protect the cardboard and wood. (this paint is made for dryer vents, barbeques etc.) I will first mask off the outside of the baffle/coupler first to prevent paint from getting on the gluing surface.
You might be able to call me anal, but when I glue parts like the motor mount, baffle and especially the fins, I let the glue fully harden for a day before disturbing it with the next glue joint. As a result, it takes me sometimes weeks to complete a rocket, doing only one or two joints a day per rocket. I do the same with glue fillets on the fins - one fillet per day. (That's 3 to 5 days to glue and fillet one single fin!) Good things take time. In my defense, in way more than a hundred launches or so, (knock wood) I've never had a fin "pop off" in any flight or landing. I just don't get how other folk's fins just seem to "pop off" from time to time. All I ever used was wood glue, no epoxy or CA. In the past I have never pre-sanded the body tube to roughen it up to take glue. I will do that now, but just learned of it recently.
So give me a few weeks to get the baffle done (and a few other rockets to sand/finish) and I'll have something new on this model.
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Picture of the ejection baffle being built (2012-06-19 00:18:01)
I took this picture to better show you what the baffle is like. Already installed in the baffle's tube coupler is the lowest baffle as seen from the bottom (engine side). Above that will be the baffle to the right, shown right-side-up. Ejection gas that makes it past this stage can't move towards the center until it passes the small 13mm tube glued to the top of the second baffle. Positioned just above that 13mm tube will be the top baffle where gas ejects from the center hole. This whole baffle assembly will be positioned as far to the top of the body tube as possible, while allowing room for the parachute, shock cord, bulkhead and a little bit more. There are two reasons to have it as far up as possible. 1) Improve stability by keeping as much weight towards the nose of the rocket, and 2) Allow plenty of space for the ejection gas to cool and prevent over-pressurization of the body tube in a too-small lower section. Worst-case, a extra strong ejection charge could cause the lower chamber to burst wide open. If that were the case the parachute would not eject but that really doesn't matter at that point because all you'd get back is a pile of cardboard and balsa scrap.
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Picture of the nose cone (2012-06-19 00:25:07)
You can see here the unusual nose cone provided with the kit. It is supposed to remain hollow, and the screw-eye is towards the side of the shoulder. This makes it easy to add nose weight if necessary, and I suppose makes it a bit cheaper to manufacture. The problem with this unique design is that the part of the plastic that takes the screw creates a nasty dip in the outside of the cone. It then has to be filled with plastic puty and sanded back to shape. I suppose the designer didn't expect that to happen, and I imagine with the cost of plastic molds it was way too expensive to remake or modify the mold.
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Nosecone, baffle, motor mount and bulkhead pictures. (2012-06-24 20:17:02)
I added four new pictures of components of the build.
1) The finished ejection baffle, seen from the point of view of the motor. You can see the Kevlar shock cord attachment, connected to the other (top) side of the baffle. This has a bowline type knot on the end of it. It's a simple and secure type of knot that won't work lose under tension and it won't pull tight into a smaller loop, but keeps the loop for tying a rubber shock cord. The knot is secured with a dab or two of glue also. It's length is sized to be just short of the body tube so it will not create zipper damage on a early or late ejection.
The silver color is a special high-temperature paint, which should be good to 1000 degrees F. A quick, thick shot of this will protect the basswood and cardboard from the hot particles of the ejection.
2) The basla bulkhead which I will conviently use to connect two good pieces of the shipping-damaged body tube, and will give me a seperate payload section for electronics and a camera. After loosing a similar payload when the screw-eye to balsa joint failed, I made sure to glue it well and added a length of Kevlar glued to the bulkhead. The Kevlar is supposed to be a backup glue-joint if the screw-eye works loose. I could use a heavy nut and bolt, but this is much lighter.
3) The motor tube and mount supplied by Quasar. 24mm inside diameter and 95mm long (D-E size). These are very good components. Notice the foil-lined motor tube, to help it withstand the heat of those long-burning motors.
4) The sunk-in area of the molded nosecone was filled with plastic putty and sanded smooth. The green filler shows where this molded-in depression was. The hollow nosecone is actually a dis-advantage to me, since I was intending the nose cone to be the forward limit of the payload guts. Worried that the payload will shift forward into the nosecone, I'll have to add some kind of stop to the end of the shoulder, probably a strip of balsa or cardboard.
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Continuing the DEFCON1 building with the body tube (2012-07-09 18:54:51)
Building the DEFCON is going well. I secured the baffle about 8 inches deep inside the lower body tube (remember I had to cut it into two pieces because of the shipping damage). On other projects I had trouble gluing baffles so far into a tube. If I spill any glue ahead of the intended spot, the baffle is likely to stick in place before I get it pushed deep enough into position, and I'm left with not enough room for the parachute. So for this I fashioned a small "cup" from folded aluminum foil and taped it to a long stick. I marked the stick 8" from the cup end, filled the cup with glue and inserted it to the 8-inch mark. When the glue was where it was supposed to be, I turned the cup over and let the glue run out into the tube 8 inches down from the end. (of course the tube was lying flat horizontal). When happy with the amount of glue, I waited for the glue to stop dripping, turned the cup over and removed it quickly before any glue dripped elsewhere in the tube.
I then stuck the ejection baffle assembly with the Kevlar mount in the tube and using a pre-marked broom-handle sized dowel, quickly pushed it all the way down into place. I turned the tube upside-down so the glue wouldn't run to the motor mount end and let the glue cure for a day. All was well. Then I glued in the motor mount and added fillets according to the directions. Note that the centering rings were high quality, they fit tight but well on both tubes. I then hardened both edges of the main body tube with a line of CA glue on the inside which soaks into the paper.
I marked the tube for the three fins. The instructions say to use the fin marking guide - but my kit didn't have one! I looked through each page of the instructions to see if it was to be cut out of the instructions and there wasn't any one in there either! I had to do it the old fashioned way, taking a strip of paper wrapped around the tube, then layed it out flat and measured the circumference, divided it into thirds and marked it. I re-wrapped it to the body tube and transferred the markings. I made sure to place one fin close to the motor clip, so the launch lug (and therefore the metal launch rod) and metal clip are all on one side - away from the ignitor wires.
I put the fins into my home-made fin alignment jig and glued them on, 1 fin at a time, giving each glue joint a full day to cure before handling the rocket. Fillets will come later. The cool thing about my home-made jig is that the body tube is held in by thick elastic bungees (shock cord for high-power rockets). This allows me to fit the fins perfectly in the jig with the body tube, then "stretch" the body tube down a bit and apply the glue. When happy with the glue I release the body tube slowly and it presses into the fin exactly where it is supposed to be. That jig is awesome!
I prepared the fins according to the instructions, being careful not to sand too much and make the fin outline smaller, the decals for the fins are designed to cover the entire fin area, so if too much leading or trailing edge is sanded down the decal will not fit. I did one mod to the fins though, I paper covered both sides of the balsa, tacked down with a generous layer of scotch photo mount adhesive. This is much - much - easier than sanding sealer to give the fins a smooth, grain free finish. Also much better on the lungs. I realize on this particular model that decals will be covering any balsa grain texture, but this way I'll have a smooth surface for the decals and I believe the paper covering adds strength to the fins also. If you use plenty of adhesive on the paper, you can then sand the edges of the fins without fear of the paper peeling up and create a smooth, invisible seam between the paper and balsa. I might also soak the edges of the fins with CA glue to harden them up against dings.
All I need to do now is glue on the launch lugs, fillet the fins and lugs, and this puppy is ready for a good priming! With the full-body wrap decals, I shouldn't have to worry about tube spirals.
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Finishing the DEFCON 1 (2012-08-08 14:10:20)
I have progressed pretty far with the DEFCON 1. I soaked in a little CA glue to the ends of the body tube and payload tube to harden them up a bit. Just a small line of glue about 1/4" from the ends of the tube keeps them from getting worn and raggedy after repeated handling. The CA glue makes the insides a bit rough and makes a tight fit for the nosecone or bulkhead, so I sand the insides down to a smooth feel.
I assembled the parachute. I was VERY pleased with the materials supplied. First the plastic material is thicker and sturdier than the usual "Estes-grade" stuff. Sure it's a bit heaver, but since this is a D-E powered rocket it should be easy to lift a few more grams. The shroud line appeared very strong, and there was plenty of it. Generally, parachute shroud length is suggested to be a minimum length equal to the diameter of the parachute. I've never had a kit that supplied more than the minimum, until this Quazar One kit. With the few parachutes I built myself I used shroud lines 2X the diameter of the 'chute, and they seem to work well and wobble less. The supplied shroud lines for this DEFCON 1 kit was enough to make 2X length shroud lines. Additionally, they included a nice heavy duty swivel to attach the parachute. After looping the shroud lines through this swivel, I dabbed glue to the confluence point to keep the shroud lines in place there. I've had other shroud lines slip through these points and cause the parachute to have one long and one short line, leaving the whole canopy lopsided and falling too fast. The supplied shock cord, which is 1/4" thick elastic and quite long was another fine quality suprise. The other end of the swivel is attached to a mid-point on the shock cord. While they instructed me to attach it to the body Estes-style, I instead attached it to the Kevlar loop I installed. I'd have to give Quazar One an A for the parachute material (A+ would have been if they used thin-mil nylon or silk, which doesn't freeze solid in cold weather).
The body and nosecone have been primed and sanded. The body tubes painted gloss white. I painted the inside end of the body around the motor tube bright red using a brush. After the paint has dried for several days, I started to apply the decals. I started with the fins and they fit nearly perfectly, but the tips of the decals did seem to stretch a bit when wet, making the fit just less than perfect. The much larger body tube decals was a challenge, getting the whole piece on straight and flat with no bubbles took a while. I had assumed the the darker aqua color would hide a few drops of red paint I left on the white, but those mistakes showed right through the decals. I also hoped the body tube spirals would be hidden by the decals, but after the decals dried the spirals show right through.
The three large decal sheets that wrap around the body are a bit oversized, so they overlap about 3/16" on one side, and it looks a bit ugly and leaves a slightly raised seam. If I had known that, I would have trimmed them a little tighter. Still, they do look pretty good from the other side, and it was a lot less work than masking, painting multiple colors and applying a dozen or so smaller decals. One large decal sheet has a cutout for the launch lug, so I started with that one to get it to align up right, even if it meant I'd end up with a gap where the white paint shows on the body tube. These decal sheets appear to be much duller and flat looking then they did before being applied, so I hope to add a bunch of coats of gloss clearcoat so it looks to have the same finish as the bare white gloss paint. It also can't hurt to protect the decals more.
I had trouble painting the nosecone to a bright silver finish. The first attempt was a bit rough, so I sanded a lot of the finish off. The second set of coats came out too thick and started to run, so I sanded that finish down again. The third set of silver paint coatings came out just right.
While the decals dry out for a few days, I am working on the payload section. I am building a small balsa wood structure to hold an Altimeter 2 and optionally a small video camera and/or a sonic locator. Since this payload section is a bit oversized, I don't want to fill the whole insides with heavy padding. The light, open balsa structure is lighter and should keep the electronics from rattling around in there during flight. Since the payload bay is quite large in volume, the normal 1/16" static vent holes will be too small to vent such a large volume of air. I have the choice of either making the holes larger, or making more of them. I haven't decided, but I am leaning towards making more holes, perhaps 6 equally spaced around the tube, and probably making a second or third set of six vent holes further up & down the tube. (If I put about 18 holes all in the same line, I would essentially be perforating the tube and inviting damage by creating a very weak point in the tube.)
That is all for now, I don't expect it to be ready for this weekend's flying, so it's maiden flight is scheduled for Labor Day weekend 2012...weather permitting.
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Final Assembly Complete! (2012-08-23 11:46:59)
OK! The clearcoating is finished and dried, now the finish is glossy. I gave it five coats of clear. I have found that one or two coats just doesn't protect the decals very much, so I have been adding much more clearcoat. I made sure the static vent holes were clear and assembled the full rocket and put it on the scale. The total assembly weighs in at 137.3 grams. If I subtract the added payload filler and bulkhead I added (11.65g) and the ejection baffle (7.7g), the rocket is 125.65 grams, or 4.432 oz. The kit card spec'd the rocket at 4.4 oz, so this is just 0.032 ounces over that. That was probably an extra half-second of glue squirt somewhere.
My best predictions for this model based on other altimeter readings is that I should expect a D12 motor to give me just over 800 feet and about 180 mph. I would rather first-test it with a C11 motor, which I predict will give me just over 350 feet and about 100 mph. The first test flight is scheduled for Labor Day weekend 2012, but I won't fly this new model if there is any significant gusts. If not then, I may have to wait for November or December.
Overall, I would have to say that this was a very easy kit to build. It was very easy to finish too, yet I have a rocket with some really good visual appeal, thanks to the decal sheets and the overall length. Now if she flies well, I will have to be bummed that Quazar One is no longer making kits. My gut feel is that this will become one of my new favorites to fly.
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First Test Flights of the DEFCON 1 (2012-09-04 15:58:08)
This past weekend was the first ever test flight of the new DEFCON 1. Several remarked that this was a good looking rocket, and I hoped it would stay that way. For this first test flight I chose the C11-5. The winds were dying down a bit, and I felt that the higher impulse, relatively light weight and long length would keep this rocket from being affected by the winds much. Fortunately it didn't seem to notice the wind.
I flew with only an Altimeter 2 on board. The motor ignited and she lifted off the rod and burned for 7/10 seconds, flying fast and straight, reaching a respectable speed of 81 mph. The readings for acceleration indicated how little the winds could affect the flight, with the peak Gs at 10.9 and the average acceleration at 5.3 Gs. These numbers were similar to a Big Bertha of about the same weight. The DEFCON then bled off the 81 mph speed in the next 3.8 seconds, reaching an apogee of 275 feet above.
Ejection fired a bit early at 4.2 seconds, but it was near perfect for this flight, as the DEFCON only dropped 2 feet in the last 4/10 seconds before the parachute popped at 273 feet. The color-coordinated parachute filled with air and the rocket came down at 8 mph, landing about 120 feet downwind. Total flight time was 27 seconds. A perfect first flight. The altitude was lower than the kit card or the apogee website estimated, claiming 366 and 411 feet respectively, but it was high enough for safety and not so that there was a chance of it drifting off.
For the second test flight, I chose the D12-5, which is probably the motor I will use most of the time. The winds continued to die down more, so I was sure this wouldn’t get lost. Though I thought it would fly well on the way up, I didn’t want this new rocket to get lost in a drift. The manufacturer claimed 980 feet for this motor, but based on the previous flight I didn't expect more than about 500 feet.
The D12 burned for 1.9 seconds, its peak thrust giving the rocket 12.4 Gs of acceleration. For the entire burn, the average acceleration was 3.1 Gs, giving the rocket enough energy to reach 131 mph on its fast, straight climb. It then coasted for 5.6 seconds but still did not slow down enough before the ejection fired slightly (2/10 sec) early as it reached 668 feet. With the rocket opened it slowed in the next 8/10 seconds to an apogee of exactly 700 feet, having climbed an additional 32 feet.
While it did not reach the altitude predictions on the kit package or the Apogee website (where I bought it), it is certianly high enough and fast enough. I'll attribute my performance loss on the fact that I added the baffle and balsa bulkhead, even though my finished rocket still came out to the total weight of the kit package.
There apparently was not enough ejection pressure because the parachute, though not stuck tight, did not leave the tube. First the empty engine casing landed on the ground, then the rest of the rocket fell to earth at 20 mph, but it landed in the grass safely, about 80 feet upwind, with no dings or cracks. The motor mount and engine clip appeared in fine condition and was not damaged in any way.
This same problem was happening with my Bandit II, which kept rejecting D12 casings and not deploying the parachutes all the time. Co-incidentally it also had an ejection baffle installed. Puzzling since this rocket was built with at least a foot of empty tube space before the baffle. I believed that was plenty of volume to prevent over-pressurization.
My current thinking is that I have learned that these baffles are not so reliable for higher power motors with their stronger ejection pressures, and I should cut/drill out the DEFCON’s baffle and use Nomex before using higher power motors. My love affair with baffles has ended, but my love affair with the DEFCON 1 has just started – She looks great and flies well! I am especially pleased with the rocket's performance on this windy day. Many of my rockets can't tollerate much wind, but this one was flying very straight and true. I can't wait to see what it will do with an E9, E12, E15 or E30 motor!
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What You Can Do
K Sonesen (June 22, 2012)