Pharos I
I was reviewing this page and found myself wondering what OpenRocket 15.03 would say about this rocket's performance. I threw together a quick-and-dirty model and ran all the relevant simulations, and my results are below. I'm reprinting the original Rocksim figures for comparison.
| OpenRocket | Rocksim | |||
| Engine | Altitude | Deployment Velocity |
Altitude | Deployment Velocity |
| A8-3 | 82.8' | -27.1 fps | 74' | 38.16 fps |
| B6-2 | 202.0' | 25.2 fps | 209' | 34.27 fps |
| B6-4 | 208' | -27.9 fps | 222' | 28.69 fps |
| C6-3 | 447' | 11.3 fps | ||
| C6-5 | 447' | -42.9 fps | 566' | 23.63 fps |
It's funny that OpenRocket shows a higher apogee for the A8-3 but lower for all the other engine types. The variation in deployment velocities is interesting also. Note that I didn't record the direction the rocket is moving at deployment when I transcribed the figures from Rocksim, though I can guess the directions are probably the same as OpenRocket gives. I don't know why I don't have stats for the C6-3 from Rocksim, but OpenRocket's figure is pretty attractive. I notice that I used a C6-3 in this rocket at the April 13, 2011 launch, and the deployment was evidently late... not what I'd expect given this simulation.
Well, it's done at last. I initially tried a combination paint job: gold, white, flat black,
and aluminum, in order from top to bottom. Looked like crap, so I repainted the sustainer
white and left just the gold cone. A few decals from some mid-ninetys Estes sets finished
it off; I've used Future as my clearcoat again, with fine results.
The fleet page entry for this rocket can be found here.
Here's my latest creation: Pharos I, a "fantasy scale" rocket.
It was on a Sunday, April 1, 1973 when the Pyramids of Mars were first recognized as artificial by astronomers, but the political trials of the time (in particular, the Watergate scandal) delayed any American project to investigate them. When at last in late August, 1974, President Ford signed the bill funding NASA's project to visit Mars, the Soviet Union was known to be well ahead of us.
The Pharos project, initiated by that Presidential signature, thus started significantly behind the competition; but the United States would not be daunted by any Russian challengers. In order to make up the travel time to Mars (in case the Soviets launched their expedition first), NASA was for the first time permitted to design and build a spacecraft with a nuclear powered upper stage.
The Pharos I vehicle thus consisted of two conventional chemical fueled lower stages generally similar to the Saturn rockets, mated to a nuclear upper stage carrying the crew capsule. This more powerful system permitted the astronauts aboard to make a much quicker trip to Mars, and to return with similar speed when their mission was done. It is no accident that this shorter mission led to fewer health issues for the astronauts (due to interplanetary radiation) than the cosmonauts suffered on their own return.
Though later missions to Mars would use a similar design, the original Pharos I rocket design was retired after only two actual missions; the vehicle's rather ad hoc design was deemed unsuitable for continued use.
Well, that's my story, anyway. The pictures attached show the rocket "naked" as I have not yet had acceptable weather for painting.
The main body is 18" of BT-70, topped with a Semroc BNC-70AP cone decorated with bits of cardstock, balsa, and birch dowels. The fins are a laser-cut Taurus fin set, also from Semroc. I used a 9" piece of BT-20 as an engine mount and stuffer tube combo. The green wrap is a piece of corrugated paper originally intended for scrapbooking.
A friend simulated the rocket for me and reports the following recommendations:
| Engine | Altitude | Deployment Velocity |
| A8-3 | 74' | 38.16 fps |
| B6-2 | 209' | 34.27 fps |
| B6-4 | 222' | 28.69 fps |
| C6-5 | 566' | 23.63 fps |
The DV values for the A8-3 and B6-2 are pretty hot; if it's really going that fast at deployment, I'm losing the chute for sure. Even the B6-4 is too fast to suit me. I can see I'm going to have to make a pretty tough chute for this bird; the standard Estes breadsack just ain't gonna cut it.
I do a lot of other things besides building and flying rockets. If you're looking for one of those other activities, click here.