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Night Rocket Lighting Examples

posted Sep 18, 2016, 12:43 AM by James Cramton   [ updated Sep 18, 2016, 1:09 AM ]
Outfitting a rocket for night flight does not need to be complicated or expensive. Here are some examples of how low-power and mid-power rockets have been converted for night flight. In some cases, you'll need to use a more powerful motor to lift the added weight of the lights. Openrocket is free software that can be very helpful in determining how the addition of battery and light weight will impact flight characteristics of a model, and it can also help you choose the best motor to fly with the new weight of the model. The article includes links to electronics that can be used to make your rocket visible at night, between $3 and $20.  

Estes Astron Outlaw
At 21 inches in length, the Astron Outlaw, and its clones like the Chrome Dome and several others, is about as small a model as I would attempt to fly at night. The reason for this is that you need enough fin area and stability in the model to support the addition of lights positioned near the rear of the model.  If practical, lights should go toward the front of the model, but in many low power rockets, that is not feasible. This lighting setup is the least expensive and simplest to implement of any--the cost is around $4 for 4 small LED lights and 4 small zip ties. The total mass of the lights is 15 grams, compared with the 71 gram weight of the model without motor. This shifts the center of gravity back half an inch, which, in the case of this model, does not risk destabilizing the model. But other models may not be as forgiving. I recommend 1 light per fin, in case the lights hang between the fins and would be blocked from view. Always fly with at least 2 lights, so that one light can fail and your model is still lit. Position the lights so that their weight sits symmetrically around the body tube. 

If you have any questions about stability of your model, use the free Openrocket software to model your rocket's new mass, center of gravity, and center of pressure, to make sure your center of gravity with your motor loaded is at least 1 body tube diameter in front of the center of pressure. And speaking of motors, for this model, a B6-4 motor was still suitable, with an deployment altitude change from 275 feet without lights, to 200 feet with lights. With a C6-5 motor, the ejection altitude drops from 750 feet to 600 feet.  Both motors would be safe with the addition of these lights, but expect the safety check in volunteers to ask if you've thought about how the added weight of the lights will affect the rocket's flight characteristics.



Estes Ascender 
The Estes Ascender is a Pro Series 2-inch diameter, 41 inch long payload rocket with a 29mm motor mount is in many ways an ideal candidate for a night rocket--large fins, long length, and an existing paylaod bay just wide enough for the 3xAAA battery case that powers the LED strip. The main lighting is a bright and feature-rich flexible adhesive-backed LED strip 2 meters long that comes with a battery case (3 AAA batteries required) and a remote control to turn the lights off and on or to change functions--from 21 different solid colors to flash, fade, or strobe features. For redundancy, I used 3 small zip ties to attach 3 flashing LED lights above the fins; in case of a failure of 1 light, there are 3 other lights to keep the model visible. 

The addition of the flashing LEDs above the fins is trivial for this size model, but the addition of the battery and LED strip in the payload bay does mean the model will need a stronger motor and/or a different delay than you might use otherwise. Use Openrocket software to model your rocket's new mass, center of gravity, and center of pressure, and to determine appropriate motors. Make sure your center of gravity with your motor loaded is at least 1 body tube diameter in front of the center of pressure, and that your motor is sized appropriately to recover your model safely, but stay below the 3,000 foot ceiling.







Balsa Machining's 3 Inch School Rocket, with payload bay
BMS's new 3 inch school rocket is a short, stubby model 29 inches tall, similar to the Estes Big Daddy, with a 24mm motor mount. The simplest solution is to not paint the white plastic nose cone, and insert 2 micro LED string lights into the nose cone, wrapped around a dowel to keep the lights spread out along the nose cone.  Generally speaking, weight added to the nose cone will improve the stability of the model, and the lights are very lightweight relative to the mass of the model, using 2 included button batteries. Adding these lightweight lights to the nosecone would not require a different motor selection.

To up the light output, I decided to drop $10 at BMS to add a 12-inch payload section that helps stabilize the model for the bigger motor needed to boost the batteries for a nice $15 LED strip on the payload bay, in addition to a micro LED string in the nose cone. This is a case where just adding lights requires changes to the model to move center of gravity forward to keep the model stable with the heavier motor needed to boost the batteries and the LEDs. Short stubby models like this are tricky that way, but lengthening the model with the payload bay from 29 inches to 41 inches, and mounting the lights and batteries in the front of the model produced a much more stable model. The original model would fly to 300 feet on a D12-3, but the longer, heavier model will reach 750 feet on an F50. D and E motors will not lift the added weight, and the added length and weight in the payload section is needed for stability.  

Use Openrocket software to model your rocket's new mass, center of gravity, and center of pressure, and to determine appropriate motors. Make sure your center of gravity with your motor loaded is at least 1 body tube diameter in front of the center of pressure, and that your motor is sized appropriately to recover your model safely, but stay below the 3,000 foot ceiling.




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