[LUNAR logo] LUNAR'clips

Volume 2, Number 4 -- July, 1995

Newsletter of the Livermore Unit of the
National Association of Rocketry

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In this issue:
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Make your mark

Enter the NAR Open Meet

by Larry Baskett, LUNAR #151

Here we go again! On Sunday, August 20, LUNAR will be hosting an NAR Open Meet with five contest events. Contests are an excellent way to test your rocketry building and flying skills against fellow enthusiasts while enjoying a demonstration of some top-notch rocketry. As a refresher from my article for our highly successful April meet, some of the rules are reprinted here. To even out the competition, there are three age divisions: A Division, age 13 and under; B Division, age 14 to 18; and C Division, age 19 and older. Your division is determined by your age as of July 1, 1995. If there are not enough contestants in a division for an event, Divisions A and B or B and C will be combined.

One revision to note: Even if you are not an NAR member, you may compete, though you will not be awarded NAR contest points for placing. This is no big deal unless you aspire to place high on the national rankings. Your name and/or NAR number needs to be written or painted somewhere on the exterior of your contest rocket(s) for identification purposes. For a more in-depth description of the rules, refer to the NAR Sporting Code (the Pink Book).

The notice is a little short on this event, so here are the contest categories so that you can start building entries right away. Although a rocket built specifically for the contest will usually out perform a sport rocket, if your sport model is good enough to qualify in the event, go ahead and enter it! You may be surprised at how well you do. At the April meet, for example, all of the fancy, ultra-lightweight egglofters (mine included) either crashed, stripped fins, or floated off to rocket heaven, resulting in disqualifications and squished eggs. The two heavier Estes Eggspress models were the only ones to return eggs successfully! So take heart, even if you are new to contests. After all, many of the first-timers in April walked off the launch field with high rankings.

1/2A motor "Hornet" Flex-wing Boost Glider Duration

This is an exhibition event because of its obscurity -- no NAR points will be awarded. It involves a hang glider- shaped flying wing made of three thin spars and a sheet of thin plastic that is folded up and stuffed down a long, skinny rocket. Upon ejection the wing pops out and begins to slowly float down. The gliding portion is timed from liftoff to landing, and these flights can be amazingly long. The longest time takes the prize. Check out the Jan/Feb issue of Sport Rocketry for an extremely informative article on this event.

A motor "Class 1" Altitude

A simple event in concept, altitude is also easy to enter. Your flight will be tracked with the club's theodolites to its peak altitude; the highest altitude wins. Even a kit like the Estes Mini Cobra (upper stage only) would do well on an A3-4T. It is a good idea to paint your rocket in colors highly visible against the sky.

B motor "Class 2" Streamer Duration

Usually you would think of streamer recovery as a way to get your rocket down quickly, but with a little ingenuity you can make a rocket float for quite a while. As with any duration event, the longest time wins. One tip to keep in mind: the optimum streamer has a length ten times its width. Any longer and the streamer does not flutter; any shorter and you are missing out on drag-producing area. A typical streamer size for this event is 6 in. by 60 in. Thin plastic, mylar, and crepe paper are commonly used streamer materials.

C motor "Robin" Egg Lofting Altitude

The purpose of this event is to propel a raw USDA Large egg to the highest altitude possible and return the egg intact. The egg must be completely enclosed in a payload compartment, which can be as low-tech as a plastic Easter egg. Nothing can be glued or taped to the egg, although a plastic baggie is a very good idea, just in case. As demonstrated by the April contest, this event is probably the most unpredictable and hilarious of the bunch. One egglofter at that launch (the owner of which will not be named here) stripped all three fins on liftoff, zigzagged in a wide arc, smacked into the street, and then ejected. To top it all off, a pickup truck drove right over the still-smoking rocket, sparing it from becoming a rocket omelet only because the tires straddled it! Needless to say, the egg did not survive. Experience from the last launch and the fact that the motors are half as powerful as before will probably mean that more flights will qualify this time. Motor possibilities include the Estes C5-3 and C6-3, the Apogee C10-4 or -7, and the Aerotech C12-4T or -7T reload.

Sport Scale

In this craftsmanship event, each entry must be a scale model of an actual prototype rocket. It is judged from a distance of one meter by comparing the entry to a photograph provided by the contestant of the original prototype rocket. The model must then make one qualified flight. You will definitely want to refer to the Pink Book on this event.

Some closing thoughts

In addition to what you will find at the local hobby shop, there are a couple of mail order rocket suppliers that are excellent sources of contest materials. Qualified Competition Rockets (QCR address: 7021 Forest View Dr., Springfield, VA 22150) carries low-cost kits for every contest category mentioned. Apogee (address: 19828 North 43rd Dr., Glendale, AZ 85308) sells the "Medalist" line of black powder and composite contest motors and may have some contest rocket materials left over from its days as a kits and parts supplier. For either supplier, send a self- addressed, stamped envelope for a product listing.

Start working on your contest entries as soon as possible. Contest day will be here sooner than you know it! (I can smell the succulent odor of epoxy fumes already.) Even if you don't plan on entering, please come anyway if you can. Volunteers to help with registration, launch control, setup, takedown, timing, and altitude tracking are always appreciated (contestants are barred from running their own events), or you can just relax and watch the show. As usual, the location is Robertson Park in Livermore. I'll see you out there on August 20!

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Equipment Care

by Warren Massey, LUNAR #007

It has become apparent from some of the damage suffered by the launch equipment during the last several launches that it is time to go over with everyone the proper use of the equipment. Parents, please bring this article with you to the next launch and take the time to go over its points with your children so that they know how to use the equipment properly too.

The launch rod is held in the stand by a thumbscrew located under the blast deflector and opposite the handle used to tip/tilt the stand. This thumbscrew must be loosened before the launch rod can be removed. Failure to do so may result in a bent launch rod. After the rod is replaced in the stand, the thumbscrew must be tightened again to hold the rod in place. Failure to do so may result in your rocket trying to carry the launch rod along on its flight. A gentle tug on the rod after the thumbscrew has been tightened will confirm if you have properly secured the rod. When changing launch rods, if the old rod has the launch rod standoff on it, remove it (loosen its thumbscrew to do so). If you intend to use the standoff, place it on the new rod. If you do not intend to use the standoff, place it on the extension cord wheel at the pad. Place the old launch rod (without the standoff) in the tube provided for idle launch rods. Do not leave it lying on the ground, there it may either be lost or get stepped on and be bent.

[launch pad schematic]
Fig. 1. The launch stand with the blast deflector plate, launch rod and launch-rod standoff.

Please use the proper size of launch rod for the size of the launch lugs on your rocket. If the rod is too small for the lugs, then your rocket is not getting the initial guidance it requires and it may take off in an unpredictable direction. If the rod is too big for the lugs, then the rocket may bind on the rod and not fly at all. When installing the rocket on the launch rod never bend the rod down to meet the rocket. Instead, tip the pad head over (using the handle) until you can reach the end of the rod without bending the rod.

[three-clip schematic]
Fig. 2. Special three-clip configuration used with clustered motors.

Use of the launch rod standoff is optional, but it helps to prevent the igniter clips from shorting out on the blast deflector and it helps prevent the deflected back blast from toasting the bottom of your rocket. If it is used, it should not be any more than about six inches above the blast deflector. Placing it higher unduly stresses the smaller launch rods and makes the launch rod less effective in initially guiding the rocket. It should be oriented such that none of it parts are directly in the path of the motor's exhaust and that no parts of the rocket (such as a motor clip) can hang up on it. Also be sure that the igniter clips don't touch it and short out.

Use of the blast deflector is not optional. When changing the launch rods make sure the blast deflector is in place before installing the new rod.

There are three different styles of igniter clips in use in the club, the common two-clip configuration most often used on single Estes igniters, a special three-clip configuration used with some clustered motors and the Aerotech clip used with Copperhead igniters. Select and use the type of clip that is appropriate for your igniter configuration. Don't use the special three-clip cluster configuration for other than three- engine clusters (see figure).

There are several ways the common two-clip configuration may be used with the Aerotech Copperhead igniters if you prefer. If you don't know how to do this, ask at a launch or a club meeting and someone will be glad to show you. If you change out a set of igniter clips, remember to place the unused ones back over with the idle launch rods. Do not leave unused clips lying on the ground next to the pad.

The alligator clips often look pretty dirty but in spite of the dirty appearance, they do a good job of supplying power to the igniter. Most ignition failures can be traced to other causes such as shorted clips of igniter wires, broken igniters or igniters not in contact with the propellant grain of the motor. If you still believe you need to clean the clips, do so gently using a fine wire brush, steel wool or very fine (600- grit) sandpaper. Just remember that excessive cleaning of the clips will wear them out prematurely.

Cleaning the Aerotech clip requires a special technique. You must fold a sheet of 600-grit sandpaper in half (grit side out) and insert the folded sandpaper into the clip as you would a Copperhead igniter. With the clip closed on the sandpaper, draw the sheet out of the clip to the side. Doing this just once will clean the clip. Doing this more than once will unnecessarily wear the clip. Under no circumstances, while using, inspecting or cleaning the clip should you attempt to "spread open" the clip. To do so will cause the clip's hinge to break. These clips are made to only be squeezed and if you do otherwise, they are going to break. You will usually find a spent igniter in the clips when you arrive at the pad to load your rocket. Remove the spent igniter and place it in the trash can located at the pad for this purpose. Also pick up any other trash you may find on the ground around the pad such as igniter plugs, wadding, motor caps, etc., and put that in the trash can too. We need to keep the field clean to be allowed to continue to use it.

When installing any of the clips on the motor igniters try to position the clips out of the line of the motor's exhaust. Make sure that the wires leading up to the clips are well out of the line of the motor's exhaust.

The yellow caution tape and its supports that delineate the keep-out zone of the flying field are not to be handled at any time. Parents take note and tell your young children.

While all the foregoing may seem obvious to most of you, it definitely is not obvious to all of you (especially the children) because mistakes have been made in every one of the areas mentioned and some of the mistakes are costing the club money it doesn't need to be spending.

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Making Custom Decals for your Rockets

by Dave Redell, LUNAR #322

Creating your own rocket decals can be really useful, whether for up scaling an existing kit, building a scale model from scratch, or just customizing your sport rocket with a cool design. The technology for doing this is still imperfect, but personal computers and laser printers have improved the situation quite a bit. Here are some tips based on my experience. Try them out, and if you find other techniques that you like, share them too!

The basic idea is to create designs on your computer, by either drawing them, using fonts, scanning them in, or any combination. You then print them on special clear film which you can apply to your rockets, just like "real" decals. And just as with real decals, the film comes in two varieties: water-based and pressure-sensitive. The water-based material is available in many hobby shops under various brands as "clear decals for copiers". This stuff is rumored to work in some copiers, but has also been known to cause trouble by melting. Most copier shops now refuse to run it through their machines, so you may want to think twice before feeding it into your laser printer.

The pressure sensitive material, on the other hand, seems to be quite safe. It's available in larger art supply stores. A typical example is Letraset Copy FX Self Adhesive Film, the regular kind and the thinner "Invisible" version. Both are available in gloss and matte finishes. A ten-pack costs $20 -- not cheap, but not too bad when you consider that one $2 sheet, carefully planned, can decorate several rockets.

I've used the Gloss/Invisible version for both B/W (on a laser printer) and color (on a color copier).

The first observation is that there are inherent limitations when using any transparent material in a computer printer:

- For either B/W or color, there is no white ink, since the printer is designed to just let the paper show through in areas that are supposed to be white. So, on the film, white comes out transparent.

- There is a related limitation for non-white areas. Solid black comes out quite opaque, but for color, you are really getting variable levels of transparency, rather than variable levels of color saturation.

The net result is that you need to either apply your decals to a white surface, or hand-paint the back side white very carefully with a small brush. Depending on your skill and the design of the decal, the latter may or may not be practical. Also, using the rear-painting technique, your decal will stick only around the unpainted edges, so bigger decals can easily become too delicate.

The other major limitation I've discovered is that although the film itself is quite thin, the paper backing it comes on is very thick and stiff. So far, I've tried five different printers and copiers, and only two of them worked:

Worked -- HP LaserJet 4L, Canon 800 Color Copier

Failed -- Xerox Color copier (two models), Tektronix Phaser Dye-sub printer

I don't recall the model numbers on the Xerox machines, but both failed; one refused to feed, and the other ate the material. The Tektronix printer failed to feed. The HP worked in straight-line paper path mode. The Canon is apparently designed to handle heavy paper (like stiff report covers) and it worked just fine.

I also tried making a one-color decal in my laser printer, using another Letraset product called Copy FX Color Foil Transfer Sheets. This is a thin film that bonds to a B/W copy, converting the black areas to shiny metallic colors. You print first, and then run the copy through again (print a blank page) with the foil taped over the parts you want to color. This seems to work pretty well, although the foil doesn't seem to stick to toner on the clear film quite as reliably as it does to toner on paper. The resulting decal (metallic red in the case I tried) comes out looking very nice.

Although I haven't torture-tested these decals yet, I feel a little nervous about the durability of the toner on the film -- especially from the color copier -- and the colored metallic foil seems quite delicate. For this reason, I tried cutting a piece from an unused section of the clear film and layering it over the part with the design, giving a double layer sandwich with the design in the middle. This results in a thicker decal with a more visible edge, but it seems very rugged. Alternatively, a good clearcoat should work. Be careful, though, since some clearcoats attack some decals. This may be a good place to play it safe by sticking with with hobby shop materials like Testors TopCoat, and avoiding the cheaper generic clear sprays found in hardware stores.

In summary, I'd say that these methods of making custom decals are a lot of fun, and can give very good results, as long as you recognize their limitations and work within them. So try it out, and if you find additional materials or techniques of your own -- send them in to LUNAR 'Clips!

Editor's note: Warren Massey has suggested printing a reversed image on transparency material and applying the result image-side-down. With this scheme, the transparency material serves a double function, bearing the image and providing an environmental shield. Reversed printing is available routinely for output from a Macintosh, and most graphics software provides for flipping of the image before printing.

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bits and pieces...

LUNAR Dust

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Aliens from Space (Really!)

OFFICE MEMO
Subject: Space Aliens
Time: 11:28 AM
Date: 6/19/95

For the first time, the US. Immigration and Naturalization Service after some prodding by the US. State Department, will officially allow two aliens from space to land in the United States.

It seems that US entry visas for cosmonauts Vladimir Dezurov and Grennady Strekalov were forgotten before the launch of Mir-18. They were launched from Kazakstan on March 14 and are scheduled to land either in Florida or California in early July aboard the Space Shuttle Atlantis (STS-71). The US State Department has, for the first time, asked for a waiver for "aliens from outer space." The INS has agreed not to arrest the cosmonauts for illegal entry into the United States.

--
Forwarded-By: Warren N. Massey

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New Club Banner

A beautiful 8'x10' four-color banner has been created for LUNAR. Lynn Kissel developed the prototype artwork which was reviewed by club members at the June launch. The artwork was transferred to vinyl by Image Signs and Banners, in the Rosewood Pavilion, Pleasanton. The cost of the sign was about $150. Look for the banner at our next club meeting and future launches.

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Free IBM-PC CAD Software!

The following information has appeared on the rec.models.rockets news group. Maybe someone would be interested in downloading this software and giving it a whirl and letting the rest of LUNAR know about your experience?

"FREE Commercial MICRO CADAM(R) CAD software is now available on the internet! To download this software please do the following:

1) FTP to microcadam.com (full address is WWW:http://www.microcadam.com)

2) Logon as anonymous

3) Use your identity as the password

4) cd to /free_software

5) Download all files there. Read the README.1st file.

Here is some more information about CADAM(R) software: CADAM(R) is CAD (Computer Aided Design) software that has been available for over 30 years. Originally developed at Lockheed Aircraft in California (and used to design the L1011 aircraft among others), CADAM(R) software is available on Mainframe computers, Unix workstations and Dos computers..."

Copyright © 1995 by LUNAR, All rights reserved.

Please send your comments to Lynn Kissel, lkissel@starship.org.
Information date: Feb. 23, 1997 lk