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Night time launch for Rocketry Club
#1
My latest project, having just mailed in our club blanket 2017 FAA Waiver request,
is to learn as much as I can about night launches.

Basically, this is anything that happens after local sunset, with lights on rockets.
I'd be interested to learn any regulations, restrictions, requirements, tips, pit-falls,
or suggestions that anyone could share.

We don't have a date yet, but we're looking at trying to plan at least one this coming year.

Any help?
Voice of experience? Cool
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#2
You need ACTIVE light sources on rockets... glow sticks and glow-in-the-dark (GITD) paint does NOT emit enough light to be seen in flight or after recovery in most cases. In a lot of cases you won't even be able to see the rocket lit by such materials from even the normal launch control setback distance. It takes a fairly bright light source to be seen in flight-- requiring an ACTIVE (powered) light source, in order to be seen during descent and on the ground for recovery afterwards. We've had rockets "lit" by GITD paint and masses of glow-sticks taped to the exterior of the rocket, and they simply *disappear* off the pad, and are *lost* in the glare from the motor firing, which is fairly bright. Also, I would usually end up hunting rockets that weren't found after landing, using my golf cart (since I live on the farm that the club flies from) and I've been within a couple feet of GITD and glow-stick "lit" rockets and not seen them. In fact one would not have been found though I was within inches of running it over with the golf cart; luckily it had also had a small LED 'lightsaber' attached to the nose cone-- unfortunately it had its battery lose contact at liftoff, and didn't come back on until it was jostled by the nearby golf cart when driving through the grass.

Which brings up my next point-- all battery powered light sources need to have their switches and battery spring contacts situated so that they are NOT vertically oriented (with the direction of acceleration at liftoff or landing), or have the batteries "shimmed" with balsa or other "hard" materials to prevent them from losing contact with acceleration of liftoff or landing. When the motor ignites and the rocket lifts off, it often produces g-forces sufficient to cause batteries to lose contact or switches to slide to the "off" position; in the case of push-button activated light sources that use a "latching relay" (or electronic equivalent, SCR, etc) losing battery contact will often "switch off" the light source and the light WILL NOT come back on when the g-forces subside and the spring pushes the battery back into contact with the fixed contact... unless the button is pushed again (which is highly unlikely in flight). BE SURE that the springs under batteries are "shimmed" so the battery CANNOT slide rearward under acceleration and lose contact, and any switches are oriented so they move perpendicular to the direction of flight (even jolts at landing can cause a slide switch to turn "off" on landing if it hits right...)

The next thing is, you need to "require" the use of red lights to protect people's night vision on the field. This is simple to achieve with red cellophane or clear sheets of red-tinted plastic available from Hobby Lobby and elsewhere. Simply cut lens covers out of the red cellophane or plastic and tape them over the lenses of flashlights and other light sources. This will prevent people being night blinded by white light sources.

It's best to conduct night launches where there's not too much light pollution in the form of lights along the horizon and reflected light in the sky from city lights. It's also important to have fairly short grass so that the rockets are easily seen at a distance on the ground by folks looking for them on foot. Flashing or blinking lights are the easiest to see in the sky or on the ground-- steady, unblinking light sources are harder to see and notice in the sky or on the ground, but are FAR superior to GITD paint or glow sticks.

Our club requires all night-launch rockets fly during daylight to "prove" they are stable in their night-flight configuration. This is a safety feature to ensure that no rockets lift off that are unstable or marginally stable and go "cruise missile" in the dark where people cannot even see them to move out of the way to avoid being hit. This is an important safety consideration.

As for light sources, "active" battery powered light sources are really the only ones that have enough brightness to be seen in flight. There's PLENTY of LED and even small bulb powered light sources available. One club member launched an Estes Hi-Jinx with a flashing LED "beer bottle lapel pin" in the clear payload bay tube successfully. It's BEST if the light source is omnidirectional, so it can be seen from ANY angle, but even this active light source facing only one direction provided enough light for a successful flight and recovery (and the flashing red light lit up the grass of the launching area-- fortunately the rocket sat on an angle sufficient to flash out across the grass-- had it landed face down so the light was obscured, it would have been very hard if not impossible to find after landing). Putting TWO such LED flashing lapel pins in the payload bay "back to back" so they were BOTH flashing outward, regardless of which one was "on top" at landing, or which way it was facing in flight, would ENSURE that the light was visible regardless of the orientation of the rocket in flight or at landing. Another successful design used LED "finger lights" taped to the bottom of translucent plastic nose cones (like the Big Bertha cone) shining up into the cone to illuminate it from the inside. It will then "glow" through the paint and the entire cone will act like a light source. The most important thing with this design is, to MAKE SURE that the slide switches (which are rather feeble plastic slides pushing contacts together) are SECURELY taped in the "ON" position and that the batteries (which are usually small watch-type button-cell batteries) are securely shimmed to MAINTAIN CONTACT throughout the g-forces of the flight, parachute deployment, and landing. We had a couple flights where the switches slid under the acceleration of liftoff or lost contact in flight, or the batteries forced the spring back and lost contact, only to come back on when jostled by the parachute opening or the landing-- best to avoid such situations though through careful shimming and taping securely.

My night rocket, the "Warp Drive", is one of those kiddie "spinning-LED-whirlygig-inside-a-clear-plastic-ball-on-a-handle" toys commonly available at most dollar stores, TSC, etc. I found that the handle of the whirlygig toy would JUST slide down inside a BT-60 tube. Using a bit of balsa and some masking tape, I taped the balsa over the button to press it down securely in flight, and attached a shock cord to the base of the whirlygig light (taping it securely to the handle as well as tying it off to the loop on the base to ensure it didn't simply break the plastic loop off at ejection and fall free). The entire whirlygig toy was slid down into the top of a BT-60 "Big Bertha" type clone (with a double-length tube, cloned BB fins, and a stand-off for the launch lug (with a second launch lug glued about halfway out one fin so the launch rod would clear the larger clear plastic "globe" on the front of the rocket. The rocket was equipped with a D12-5 and a large parachute with a slide bead on it to ease deployment shock by momentarily "reefing" the chute at ejection. The rocket was loaded on the pad and made a beautiful spiral light trail as it took off, which was soon overpowered by the bright flame of the D12, but once the rocket burned out, the spiral light trail of the spinning LED whirlygig was HIGHLY visible in flight to apogee, at which point the rocket ejected the chute and the spinning LED whirlygig, floating down under the chute and partially illuminating it, made a very "UFO-like" trail visible all the way to landing.

With cheap, readily available LED strips, flashing beacons, battery-powered LED Christmas lights, etc the only REAL limitation on night-launch rockets is one's IMAGINATION. There's a LOT of toys that are available too which can make EXCELLENT light sources for night-launch rockets as well-- a few years ago I bought several "LED swords" that were about 24-30 inches long at the dollar store around Halloween-- they are a roughly 6 inch long plastic handle with a multi-press "mode button" on the side to press to turn it on (which will need to be protected once turned on to prevent it from turning off in flight if it's bumped, or replaced with a more reliable activation method) which will turn the light on one solid color (which multiple presses allows one to "scroll through", a flashing mode, and a "phasing mode" that goes through ALL the colors as the LED's ramp up and ramp down in various combinations. It has 3 LED's that shine up the clear plastic "sword" (round clear tube) above the handle, through a translucent inner sleeve of milky-colored plastic which makes the entire "sword" light up. The clear plastic tube had bats and pumpkins on it, but I found I could very carefully scrape those off with a hobby knife to make them into "warp nacelles" for a successor rocket to the "Warp Drive" original rocket.

I also got my daughter a number of blinking LED toys, usually worn around her neck, at various festivals and such having fireworks or other night activities... the hardest part is convincing her to part with them afterwards for rocket flight. I also bought several of those translucent tube plastic flashlights available in the camping section of various stores in various colors... they're powered by a stack of button cells and have a solid white LED "flashlight" on one end and flashing or solid LED facing the inside of the translucent tube, usually with a built-in "emergency whistle" on the upper end. These are available in various colors.

I also found a "rocket shaped cup" that one of my nephews got from a Sonic restaurant a number of years ago that I'm going to convert into a night launch rocket... It will look something like an "Honest John" with large fins and the "bomb" attached to the front, with a "bomb core" of flashing LED battery-powered Christmas lights inside the "warhead" which will descend under parachute, with the rocket below. It should look really cool when completed.

The main thing is, ensure stability-- adding LED powered stuff "up front" usually increases stability by moving the CG of the rocket forward... adding light strips or flashing stuff to the BACK of the rocket tends to be DESTABILIZING since it moves the CG rearward. ENSURE that the design is stable by flying in "all up configuration" for the night launch during daylight beforehand...

Later and have fun! OL J R Smile
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