The Launch Pad - Rapier {Kit}

Contributed by David Urbanek

Manufacturer: The Launch Pad
Rating
(Contributed - by David Urbanek - 07/16/99)

Rocket PicIntroduction:
This is a scale model of a British surface to air missile. The kit is on the line of an Estes kit for balsa quality and body tube wall thickness. In other words, it's a lightweight rocket, that looks huge. The idea behind this is you can launch this rocket many times for the price of one really high power launch. However, the rocket is so lightly constructed, I doubt it will handle the abuse of lots of launches.

There's a lot of balsa on this kit, so I learned a lot about handling and sealing balsa that I didn't know before. Also, they use a commercially available plastic nose cone with a paper cone attached to the front to get the desired shape. It's a major chore to get this put together right. If you're looking for a fast build, keep looking. If you're looking for an impressive rocket for only a little money, this is it.

Scale is good...
These guys have one of the slickest web pages in rocketry. They also have an excellent selection of scale military kits. Most of the missiles they offer are designed to be only marginally stable and actively controlled. The means that it's quite a feat to make them into stable model rockets. All their rockets are based on a BT80 (2.6") or BT60 (1.6") body tube. If you're at all interested in getting into scale rocket building, get one of their kits as a second kit. These are not easy, or trivial projects most of the time and making a successful model will require experience from other kits.

Construction:
The materials for this kit ranged from high quality to sub standard.

One of the balsa sheets and the centering rings were of superior quality. The centering rings are made of heavy card stock and laser cut. They fit perfectly with no fiddling or sanding. One of the balsa sheets was better than average: close grained, sturdy and flat.

The tubes, nose cone, balsa strips, launch lugs and parachute kit were all of average quality. I would have preferred a nylon chute for a rocket this size. I ended up using the mylar for a streamer for another rocket.

The other balsa sheet, motor clip and clay nose weight were of inferior quality. The motor clip was already slightly rusted when I got it. The kit comes with two pieces of balsa and the second sheet was of very poor quality: much too soft and warped. I should have replaced it right away, but I didn't. The clay nose weight was rock hard. I tried to remedy this using the kit instructions to no avail. I ended up carefully weighing the clay on a triple beam balance and substituting a like amount of lead & epoxy.

The instructions are sparse, but adequate for an experienced modeler. Also note that unless you are experienced and have good CP program backing you up (and VCP doesn't qualify for this model), don't modify anything. RockSim 3.01 is just enough to keep you from making mistakes.

Construction of this kit requires a lot of balsa work. There is no indication of taper to any of the fins, so I didn't taper any of them. I just cut them square and sanded them this way. Finishing the soft balsa fins was a pain. I tried a number of methods. You can wick thin CA into the balsa to strengthen it, but when I tried this with the very soft balsa, it warped even more. I ended up buying new balsa wood. The very best way to finish balsa fins is this: using very thin epoxy (I use the RAKA epoxy system) coat a thin layer of epoxy on one side of the fin and lay a piece of 3/4 oz fiberglass on it. When everything is dry cut and sand off the stuff hanging off the ends. Then do the other side. It strengthens the fins and finishes them with almost no weight increase.

The nose cone is a serious pain unless you're a wiz with making card stock cones. I'm not and had a hell of a time getting this right. To get the right nose shape the blunt ogive cone has a card stock cone extension glued to the front. Then you must fill and sand until it all blends together. Steaming the cone helps. Once I had the cone formed, I just pressed it in place on the nose cone. Then I put a bit of soft clay and a dowel up into the cone. By spinning the cone and noting if the cone was off center I finally got it straight. When I got it centered, I wicked very thin CA into the base of the paper cone to hold it in place. Then I hardened the cone with CA, epoxy (very thin coat) and then I filled it with spackling compound which I also hardened with very thin CA.

Rocket PicThere are three centering rings provided. The third acts as a parachute shelf about 12" back from the front end. It keeps the parachute from sliding back on boost. I added a short piece of epoxy reinforced bamboo across the 'chute shelf and used this as the shock cord anchor. With the addition of a baffle, this idea will be incorporated into all my rockets 1.6" and larger from now on.

There is no indication of any surface detail for the rocket and the paint information is extremely sparse. This kit is, at best, a rough sports scale model. Don't expect to enter it into any contests unless you're going to do a lot of research and additions first. There is almost no scale information worth using in the kit or instructions. They also don't indicate where the CP is supposed to be, or the CG. This is a pretty inexcusable in a rocket kit whose stability is hard to estimate. My rocket came out weighing 8.9 oz. The empty CG is 21.5" from the nose tip. The CP is about 28 3/8" from the nose tip according to RockSim 3.01.

For launch lugs I substituted 1/4" mylar lugs. This is so I can put it on a longer, stronger launch rod. There is no instructions on where to put the launch lugs. I placed one on the mid-body seam (about where the CP is) and one 2" from the tail.

For the price of the kit, you get a big rocket that is a big project. I don't expect everyone will get one piece of good balsa and one piece of crap. Still, it does have almost no scale data and lacks stability information.

Construction Rating: 2 out of 5

Flight/Recovery:
This flies nicely. I wouldn't fly it in any wind, though. The stock chute is terribly undersized for the altitude I fly from (4300') and the ground is very hard here. I substituted a 28" nylon chute and will be getting a 30" mylar chute from ASP. You'll need a sturdy rod and launcher. Under E18 power it boosts slowly and still gets plenty of air.

I have an Aerotech 24/40 system too, so I use those motors in addition to the recommended motors. Here's my motor chart with expected altitude and delay recommendations:

Motor 4300' elevation Sea Level
D12-3 305' 265'
D15-4T 495' 435'
E15-4W 935' 840'
E18-4J 930' 840'
F12-5J 1020' 915'
F24-4W 1085' 985'

It's a real nice flyer and a big rocket. Do not fly it in gusty winds, though. Wait for a calm day.

Flight Rating: 4 out of 5

Summary:
It's a bear to build, not everything you need is in the kit and it irks me to not have a really scale model. What this kit has become is a prototype for a scratch built Rapier some time in the future. It will require a lot of research on my part to make a truly scale Raper. Still, for a sport flyer, it will be fun to put up every once in a while.

Overall Rating: 3 out of 5

Flights

Comments:

avatar
D.J.D. (October 6, 2001)
The Rapier was the first ?big? rocket that I built when I became a BAR. I flew it at least six times, most of the flights where wonderful. It needs an E motor to fly well though. Unfortunately, I crashed it ? my fault I think. I was so heart broken that I decided to buy another kit. I used all the patterns to build a MUCH heavier version of the rocket using 1/4 in thick balsa fins, Aerotech tubes and nose. The rocket is much longer but flies great on an E-30. My wife painted it a cool camo design. I think I am going to build the actual LP kit again though. Thank you Launch Pad.

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