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At the 2009 Space Access Society meeting April 2-4 2009 two of the 16 presently registered
entrants for the N Prize presented brief introductions to their entries.

This is the entry for Microlaunchers.


N Prize Team List

Microlaunchers was the fifth listed team, as of June 6, 2008 More important than the prize itself, this creates a lower threshold entry point for developing flying launchers From there, it should be relatively easy to extend the performance of launchers to the originally planned capability of sending small spacecraft to escape velocity, among the Near Earth Asteroids.


Microlaunchers is:

Microlaunchers is an attempt to do in space what the Altair and its kind did for computers--to make space exploration available for participation by many--more than just something to read about


Launcher Outline

The N Prize vehicle design is reduced in scale from this Cansat and a Cubesat launcher then being studied. The Cubesat launcher was to have a Gross Lift Off Weight (GLOW) of 100 to 200 kg and place a single 1 kg Cubesat into LEO or 100 to 200 grams to escape from Earth. For N Prize the estimate is about 60 kg GLOW. All three stages are to use LOX and stages 2 and 3 to use butane or propane for the fuel. Should an ethanol sponsor be found, the first stage could use ethanol for fuel. The third stage propellant tanks could be 24 ounce beverage cans if a beer or other drink sponsor be found. Otherwise the tanks will be made from nickel, electrodeposited onto wax forms.


Launch Trajectory

Stage one is to perform the staging at an altitude over 60 km where the air is low enough in density for the upper stages to operate in the near vacuum and to experience low aerodynamic loads. Stage one will be guided manually by optical tracking with a launch pad mounted video camera and by launching in clear weather.


Stage One Aerodynamics

Scaling rockets to small sizes strongly affects the aerodynamic behavior, tending to make drag have a much larger effect on performance. By deferring the higher velocity to highar altitudes, this can be overcome at the expense of somewhat larger "gravity loss", the effect of climbing against gravity. Rockets work best if they accelerate quickly. The dynamic pressure, or Q, can be measured by a pitot tube as done with aircraft and that can be used to limit the aerodynamic load. Shown here are two plots of an ascent, with conditions the same except the Q in one case is limited to 33 kPa, about equivalent to 450 knots at sea level (450 KIAS). A number of spreadsheet calculations are being done with various thrust levels and maxim Q. Another benefit to reducing Q may be a more gentle ride for the upper stages.


Upper Stages Guidance

Guidance for the upper stages will be based on a servo controlled optical horizon sensor with two accelerometers mounted to measure the component of acceleration along the vertical at any moment, and the forward horizontal direction. Or, the local radial and tangental velocity components at any time during the ascent. The azimuth, or heading for the orbit trajectory will be determined by a magnetic sensor or optically sensing the sun position, which at any planned launch location and time, would not be directly overhead.



The satellite must have a mass between 9.99 and 19.99 grams, and for this design, 18 grams is assumed. It is to be a batterty powered RF transmitter which is to transmit for a time long enough to have completed 9 orbits, or about 14 hours and be detected after that time has elapsed. Cell phone components are well designed for this application, and by having the power about 200 mw and on about one percent of the time, the power requirement is low enough for a battery weighing about six grams. Some useful data can be transmitted by means of a simple analog pulse position code. Illustrated here is a repeating pattern of about three seconds, with one pulse being a syncronizing pulse, and each of four shifting to give analog data. Here: 1. one for satellite ID, as there may be more than one up at a time; 2. internal temperature, to see if the chosen passive coating is right; 3. the voltage of the battery, to see by it's decline if the transmiasswion will last the 14 hours required; 4. and the amount of propellant in the third stage when the satellite is ejected, to show how much mass could have been orbited. The last information is useful, as about 100 launchers are to be built, and after five to ten are expended in prize attempts the remainder are to be marketed as a product--a satellite launch kit.


Development Strategy

The development strategy includes, in addition to the design, fabrication, testing of the components, planning of a set of locations or environments for each phase of the work. Then, organizing the work to fit the several regulatory regimes so the effort so that expenses incurred can be scheduled. In addition, the design of the launcher, and other portions can be made to fit the regulations. For example, use of the new amateur rocket regulations can allow testing and qualification of the stages before the launch license application begins. This will enable the "entry threshold" to be much lower and less expensive than is typical of launch vehicle development efforts.


The 4 Locations

The work can be organized to use four locations, beginning with a shop facility in which the design, fabrication and testing of the components takes place, with no flights involved. Then, working under the amateur rules, performing in uncontrolled airspace that is far away enough from any airports, tests of the launch process, both for on-the-ground and spar buoy mounted launch hold down device. The engine operating time will be for a few seconds--enough to test the launcher and rise high enough for a parachute to deploy, but remain in uncontrolled airspace. The notification process for this is relatively simple. Under the new amateur rules, flights as high as 150 km are possible, but a large clearance around the operations is required as is a longer notification process. There are a few locations in the lower 48 states where this can be done. Actual space launches, whether to LEO or escape, will probably have to be done from the east coast, launching out over the Atlantic. Launch licenses and probably export licenses will be required.



The sets of rules can be dealt with incrementally, with the simplest occuring first, and the more diffult, with more time requirements and costs scheduled to occur later. Not mentioned here is that an RF transmission from a LEO satellite will require an FCC license. An escape spacecraft using optical transmission will not. This problem might be overcome by seeking a partner who has experience with Cubesats and has or could get the FCC license.


Make History Repeat

The objective is to bring back the events of the computer revolution and the intense level of interest that spawned, together with the many large industries, and the computer on which you are probably reading this. The means, technology, and component parts to do this are now widely available.

Defensive Publication

One of the reasons for publishing technical descriptions of the designs is,
in the event they are patentable, I will have one year from publication
(April 2, 2009 in this case) to file for a patent.

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: 2009 Charles Pooley --
Presentation Date: April 2, 2009