Here’s the remastered final version of Andrew McCombs’ classic documentary “The Principia Process,” which chronicles the spring 2002 launch season, and the beginnings of Team Principia. Watch and enjoy.

Building a liquid-propellant rocket engine is pretty much the pinnacle of amateur engineering projects.

The 1967 book How to Design, Build and Test Small Liquid-Fuel Rocket Engines can be read online, or you can download the entire file in zip format.

From the introduction:

The purpose of this publication is to provide the serious amateur builder with design information, fabrication procedures, test equipment requirements, and safe operating procedures for small liquid-fuel rocket engines.

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The simplest model rocket launch controller is the Estes Electron Beam, which is powered by four AA batteries and comes with 17 feet of launch wire and micro clips for attaching an Estes igniter. This system is adequate for launching small models with a single black powder motor. However, for firing a cluster of motors, or for igniting composites, a battery with more amps is required. In addition, spectators of high-power launches will need to be farther away from the launch pad than 17 feet. Unfortunately, electrical resistance in a long launch wire negates some of the advantages of using a larger battery. This problem can be solved by using a relay switch located near the launch pad, allowing the main battery to sit as close to the motor igniters as possible, while the launch controller remains at a safe distance.

The LC-3 Electronic Relay

The LC-3 is the third iteration of Principia’s electronic Launch Control system. It is based on a similar design by Eric Ohmit, but differs primarily in that the controller is powered independently of the main battery. The full system (pictured below, left) consists of a Control Box, a Relay Box, a pair of connector cables to the battery and the igniters, clip whips for multiple igniters, and 100 feet of RJ-11 (telephone) cord to connect the control box with the relay. [Click any photo to enlarge.]

The Control Box (pictured above, right) incorporates a key-operated arm/safe switch, which ensures that only the designated range safety officer (RSO) can initiate a launch. In addition, the control box provides a green LED continuity indication, which tells the operator that the circuit is complete and that the battery and igniters have been properly connected. Continuity is confirmed by flipping the red “Continuity” switch to the ‘on’ position and noting the illumination of the green LED. The LC-3 is then armed with the key switch, which causes the red “Arm” LED to light, and a high-pitched piezo buzzer will sound, indicating to all spectators that the rocket is ready to fire. When both the green “Continuity” LED and the red “Arm” LED are illuminated, the red “Launch” button will become active and also illuminate, and the relay can then be engaged by depressing the button. If all goes well, the motor will light and the rocket will launch.

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The Rocket-Mounted Video Camera Project came to an abrupt end as the V-2 model rocket Prima Donna suffered a catastrophic failure (CATO) on its first launch attempt. Although tragic, the CATO was captured on video from multiple angles, and represents a classic case of a rare Estes engine failure. [Scroll down for videos.]

An examination of the video and debris is currently underway, but the consensus is that the extreme cold (-15°C) caused the propellant grain to separate from the interior wall of the rocket motor case.

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The Rocket-Mounted Video Camera project is nearing completion. Prior to the flight test phase, however, prudence demands that we run a few simulations to ensure that the rocket will have a safe and stable flight.

Initial Evaluation

Before beginning construction, we made a few ballpark calculations using (a free trial version of) RockSim, a Windows-based model rocket design tool, to verify that the addition of the camera wouldn’t adversely affect the model’s flight characteristics. To increase performance, we also swapped the specified D12 engine for a higher-impulse E9.

The images below show the results of this evaluation. You can see from the flight profile graph on the left that the predicted maximum altitude with the E9 motor is nearly 1000 feet. The stability diagram on the right shows the center of gravity (CG) position with the E9 engine, but without the addition of the video camera in the nose.

Although the CG was a little further aft than is desirable, we determined that the addition of the video camera and battery pack to the nose of the rocket would only improve stability, and that the E9 motor would help compensate for the loss of performance that the camera’s weight would create. Based on this preliminary analysis, we decided to go ahead with rocket construction, using an Estes E9-8 engine, the video PCB and a 2AAA battery pack.

Now that the build is complete and the camera is installed, we need to revisit these calculations with the actual mass measurements, to assure that we have an accurate picture of the flight profile before the first test flight.

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The idea comes from MAKE Magazine, Vol. 7: Hack a $30, “single-use” camcorder and fly it on a model rocket. The project involves disassembly of the plastic camera housing, soldering a stripped USB cable onto the camera’s circuit board, hacking the board’s embedded software to make it reusable, then mounting it in the nosecone of an Estes rocket kit. With persistence, the project can be completed in a long weekend, and the results are spectacular.

The CVS “Single-Use” Camcorder

The Pure Digital One-Time Use Video Camcorder is marketed by CVS and Rite-Aid pharmacies as an inexpensive and user-friendly device for capturing family memories, vacation outings and the like. With only three buttons, it is simple enough for anyone to use. A 1.5-inch color LCD serves as a viewfinder, and allows you to watch a playback of the most recent clip. The camera’s firmware and data are stored on a Samsung 128MB non-volatile flash memory chip which holds roughly 20 minutes of digital video.

The palm-sized camera costs less than thirty bucks, but there’s a catch. When your 20 minutes are up, you take the camera back to CVS, where they charge you a $13 processing fee to download the video data and burn it onto a DVD for you. The camera’s memory is then cleared, but you don’t get to keep it; it gets sent back to the manufacturer for repackaging and resale. Well, with a little tinkering and some steady-handed soldering, we’ll make our own camera interface, turning this product into a compact, reliable and — best of all — reusable digital video platform.

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Note: This is an old list of NewSpace links that I compiled way back in the Principia 1.0 days, and it’s just now making the transition over to the Labs. My apologies if some of the links are broken!

News Articles

• Space Tourism Taking Shape, CNN.com.
• $100 Million Moon Trip: Space Tourism’s Hot Ticket, National Geographic News.
• NASA Launches Startups for Ships, Wired News.
• Race for Next Space Prize Ignites, Wired News.
• How We’ll Get Back to the Moon, NASA.
• X Prize Losers: Still in the Race? The Space Review.
• SpaceX and The First-Launch Crisis, The Space Review.

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Designer: Adam Lapensky

Motor Manufacturer: Estes Industries
Propellant Type: Black Powder
Motor Designation: (3) C6-3, (1) E9-8

Motor Diameter: 18 mm (C), 24 mm (E)

Motor Length: 70 mm (C), 95 mm (E)
Propellant Mass: 0.0682 kg
Total Motor Mass: 0.1375 kg

Total Impulse: 55.5 Ns

Burn Time: 3.09 s
Maximum Thrust: 61.74 N
Average Thrust: 23.24 N
Specific Impulse: 83 s

Notes: Designed in the spirit of Ralph Steadman, Leadbelly is clearly the most evil vehicle in the fleet. With forward-swept fins on the tail, and aft-swept canards on the nose, all sanded to razor-sharp points, this baby was bound to draw blood at some point. Unfortunately, it was Adam himself who suffered from the ghastliness and madness of his own creation.

Designer: Brad Gambach

Motor Manufacturer: Estes Industries
Propellant Type: Black Powder
Motor Designation:
(2) D12-3, Booster
(1) D12-0, Booster
(1) E9-8, Sustainer
Motor Diameter: 24 mm
Motor Length: 70 mm (D)
95 mm (E)
Propellant Mass: 0.0991 kg
Total Motor Mass: 0.1869 kg

Total Impulse: 78.39 Ns

Burn Time: 4.74 s
Maximum Thrust: 89.19 N
Average Thrust: 30.63 N
Specific Impulse: 81 s

Notes: The Black Thruster combined both clustering and staging of motors to achieve excellent performance and spectacular launches. This combination of engines sported the longest burn time of any vehicle in the fleet, and the highest max thrust of any black powder rocket, providing a fantastic viewing experience.

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Designer: Andrew McCombs

Motor Manufacturer: Estes Industries
Propellant Type: Black Powder
Motor Designation: (3) E9-8
Motor Diameter: 24 mm
Motor Length: 95 mm
Propellant Mass: 0.1074 kg
Total Motor Mass: 0.1947 kg

Total Impulse: 85.5 Ns

Burn Time: 3.09 s
Maximum Thrust: 58.41 N
Average Thrust: 27.06 N
Specific Impulse: 82 s

Notes: Conceived, designed and constructed in one long, intoxicating night, Black Betty represents the essence of Jules Verne’s “genius of will.” In one monumental push, Andrew brought this flagship to fiery life, and a mere two days later, she flew. Flaunting three “E” impulse engines, Black Betty was known for her thunderous, roaring liftoffs and commonly climbed beyond visual range. Though she suffered from several initial recovery system anomolies, much like Mach Me, she always returned in one piece. Subsequent overengineering of the shock cord restraints solved these problems, and Black Betty remains in the Principia fleet to this day.

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