May Meeting Program

Night Launch Payload

This was the fifth part in our continuing project to get club members up to speed on building a High Power Rocket.  If you missed the meeting here is the basic outline of what was discussed.  Don't miss next month - Payload Construction.

  1. Light Sources
    Various types of light sources can be used to make the rocket visible at night:
    1. Xenon Strobe
      This is the best, most visible type of light for night launching.
      2. Advantages:
      Non-directional
      Visible for several miles (line of sight) 
      Can be mounted in either clear or opaque payload sections
      Disadvantages:
      Expense
      Availability
      Requires batteries, switches, etc.
    2. LEDs
      New generation “super bright” LED’s are good for “pad glitter” applications and/or lower power flights.
      3. Advantages:
      Lightweight
      Low cost
      Disadvantages:
      Directional
      Limited range
      Requires batteries, switches, etc
    3. Glow sticks
      Good for general illumination on the pad, but of limited value otherwise.
      4. Advantages:
      Lightweight
      Low cost
      No batteries required
      Disadvantages:
      Not very bright
      Not reusable
    4. Regular LEDs, Christmas lights, flashlight bulbs, etc.
      Good for general illumination on the pad, but of limited value otherwise.
      5. Advantages:
      Lightweight
      Low cost
      Disadvantages:
      Not very bright
      Requires batteries, switches, etc
    5. Electro-luminescent strips
      This is a relatively new type of device consisting of an organic phosphor sandwiched between two conductors. When an AC signal of sufficient voltage and frequency is applied to the conductors an electric field is formed across the phosphor. This causes the phosphor to emit visible light.
      EL strips require an inverter to convert the DC to AC. Frequency determines the brightness. They will last thousands of hours, however the higher the frequency you drive them at the shorter the life. While they are flexible, you cannot put a sharp crease in them. If you do, the backing conductor will break and the part of the strip after the crease will no longer light up.
      Also you can get a nasty little jolt if you touch the hot wire with the inverter power on. The connectors on the EL strip from Night Launch (www.nightlaunch.com) are a bit loose so be sure there is nothing that can fall against them during the high-g forces of launch, or they might slip off. Other manufactures have a more secure attachment method but they are more difficult to mount cleanly.
      These strips of “electric vinyl” can be seen both on the ground and at altitudes up to 2000 feet
      6. Advantages:
      Fairly bright
      Several colors available
      Unique designs possible
      Disadvantages:
      Expense
      Availability
      Requires batteries, switches, inverters, etc.
    6. EL wire
      This is a new type of lighting. It consists of a thin vinyl tube that contains a phosphor-coated wire wrapped with a pair of hair-thin bare wires. These are illuminated in a manner similar to EL strip, where an AC signal with the proper voltage and frequency will cause the wire to glow. Like EL strip they require an inverter to convert the DC of the battery to AC of the proper frequency and voltage. They come in many lengths, and if you don't mind soldering, you can make your own custom lengths.
      Attachment to the rocket, can be with clear packing tape, or you could try tacking it down with some strategic drops of epoxy to get your main design set, then you can go back over the rest of the wire with more epoxy to set the entire pattern. You can also use CA or silicone glue.
      The life of EL wire can be from 1600 hours to over 5600 hours. The wire will dim with age, and the life of the wire is determined by the frequency used to drive it. Most are driven with 2000Hz, which should give a useful life of over 2000 hours. If you drive it at 4000Hz it will be very bright but will last less than 1600 hours. Conversely, at 400Hz it will be much dimmer, but will run for over 5600 hours. Most any of these lifetimes will be many times longer that you average night rocket's lifetime.
      EL wire is very flexible and can be shaped almost any way you wish. It is available in many colors and is visible both on the ground and to at least 800 ft. It may be visible to higher or lower altitudes depending on the density of your pattern.
      7. Advantages:
      Fairly bright
      Several colors available
      Unique designs possible
      Disadvantages:
      Expense
      Availability
      Requires batteries, switches, inverters, etc.
  2. Applications
    1. Low-power flights
      For flights up to 500 feet, any of the light sources mentioned above can be used
    2. Mid-power flights
      For flights between 500 feet and 2000 feet, Xenon strobes or EL panels are preferred. Glow sticks and small LEDs become invisible at apogee, but can still be valuable for locating the rocket after it lands.
    3. High-power flights
      For flights in excess of 2000 feet, only the Xenon strobe light will be visible at apogee. Other light sources can be valuable for locating the rocket after it lands.
  3. Motor Selection
    1. Black powder
      Black powder motors are beautiful at night and have several advantages:
      • Low cost
      • Ease of prep
      • Do not “blind” the observer
    2. APCP motors
      Various propellant formulations lend themselves differently to night flights:
      3. White Lightning
      Beautiful to watch at night
      Tends to “blind’ the observer
      Harder to “reacquire” the rocket after motor burnout
      Blue Thunder, Redline, Green Gorilla, etc
      Beautiful to watch at night
      Not as bright as WL
      Easier to reacquire target
      Blackjack
      Not much to see at liftoff
      Lots of smoke
      Easy to reacquire target
  4. Mounting Options NL payloads can be mounted in various ways:
    1. Dedicated payload section
      For Xenon strobes and EL panels, a dedicated payload section is recommended. These types of light sources require batteries, wiring, switches, etc, which must be permanently mounted in some fashion.
    2. External attachment
      Some small light sources, such as small self-contained LEDs, can be surface-mounted using either epoxy or magnetic attachment.
  5. Batteries
    Battery placement depends entirely on the light source being used:
    1. Xenon strobes
      Batteries may be internal to the strobe unit itself, if using a commercial unit, or may be mounted internally in the payload section for “home-brew” strobe-tube arrays.
    2. EL strips and wires
      Batteries and other required circuitry will usually be mounted internally in a dedicated payload section
    3. LED’s
      Some small LED packages have integral battery mounts within the package. This provides the option of mounting the entire assembly externally.
      Home-brew LED arrays would generally use an internally mounted set of batteries.
    4. Glow sticks
      No batteries required
    5. Battery weight
      If using 1.5V batteries, substituting a smaller battery can save weight. Adaptors can be made from foam to make a AA work in place of a C battery, etc. A website called X-treme Geek (www.x-tremegeek.com) has a nesting set of shells that will adapt a AAA battery to AA, C and D. (Price $3.99)
  6. Switches
    7. Power switches provide flexibility with Night Launch payloads
    Can be very useful if properly installed
    Can be affected by G-forces
    Switch placement
    Switches that are accessible on the pad allow:
    • Last minute arming of light sources before launch
    • Conservation of battery power
    External switches
    Have the same advantages as “accessible” switches
    Have the disadvantage that they may be inadvertently activated during the flight or recovery.
  7. Ease of Prep
    Prep becomes much more difficult in the dark
    8. Complete as much prep as possible BEFORE dark
    Building motors
    Installing recovery system
    Prepping altimeters, timers, etc.
    Installing batteries in NL payloads
    Making internal circuitry connections, etc.
    Power-up and testing of NL payloads
    Externally accessible switches become very valuable after dark!
  8. Payload Portability
    Self-contained NL payload sections can be moved from one booster to another
    • Allows more than one flight for a given payload
    • Requires that the payload be recovered before it can be re-flown
  9. Other Considerations
    10. Audio beacons

    Don’t forget audio locators, cornfield beepers, etc. Many styles available, see Resources page.
    Radio beacons
    Radios also work at night
    Highly recommended for HPR flights
    Consider the terrain
    Recovering a rocket from tall weeds, crops, etc, is difficult even in the daylight
    Strongly recommend audio and/or radio beacons in addition to lights
    Sod farms are ideal for night launches
    Fewer places for the rocket to hide
    Even low-power lighting may be visible on the ground for some distance

Night Launch Sources

All Electronics Corporation*
Discount electronics, parts, LEDs, strobes, etc.
http://www.allelectronics.com/index.html

MariSafe
Marine supplies, strobe lights, etc.
http://www.marisafe.com/Store/viewItem.asp?ID=104550298&CID=10450000&FLT=104550298

Night Launch.com*
EL strips, inverters, etc,
http://www.nightlaunch.com/index.html

X-treme Geek
Battery adapters and other cool geeky stuff,
http://www.x-tremegeek.com

Live Wire Enterprises
EL wire, drivers and sequencers,
http://www.elbestbuy.com

Hovering Studios
EL wire, drivers and sequencers,
http://www.hovering.com/coolneon/index.html

CooLight Electroluminescent Wire*
EL wire, drivers, sequencers, and connectors
http://www.coolight.com

EL Wire Cheap
EL wire, drivers, sequencers, custom length services, cold cathode lights
http://www.elwirecheap.com

Glowire*
EL wire, EL sheet & strips, and LED products
http://www.glowire.com

NDS Products, Inc.
Strobes, battery powered light sticks, flashlights
http://www.ndsproducts.com

Blue Point Engineering
LEDs, flasher modules, EL wire, EL sheet, drivers, etc.
http://www.bpesolutions.com/lghtefx.html

Pratt Hobbies*
Audio beacons, rocketry parts, kits, etc.
http://www.pratthobbies.com/

Adept Rocketry*
Audio beacons, radio locating equipment, altimeters, etc.
http://www.adeptrocketry.com/

* Indicates at least one person in the Club has actually done business with this company and had no problems.

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Page last modified Thursday, August 25, 2005