CarVac
13th February 2012, 08:23 AM
Being a cheapskate, I like to get the most fun I can on the dollar. So, I started to plan an ultra-cheap rocket which nonetheless would have insane performance.
No rocksim or openrocket file because the rocket is so incredibly simple: it's a 1-foot (or maybe shorter) 29mm phenolic tube. Fiberglassed on would be three 1/32" thick, 1" chord by 1.25" semispan carbon fiber fins made of 1x12 stock from McMaster Carr. Atop it would sit a Shockwave 29mm nosecone with a Beeline transmitter in it. Some sort of durable chute or streamer would bring it all down safely.
I figure that this will come in at about 6 ounces empty, so for max fun I plan on flying it on a CTI H410 Vmax and watching it disappear. And when I say disappear, I mean now-you-see-it-now-you-don't: according to Rasaero, its acceleration peaks at 166 g's 91 feet off the ground, and it hits Mach 1.46 at 350 feet off the ground. With a 3-foot tower launcher, even ignoring the gains caused by confining the exhaust gases, the rocket would go 136 ft/s off the tower.
An alternative motor (my personal favorite due to its impulse to size ratio, actually) that would allow me to further shrink the airframe is the Aerotech G138T. Despite the lower impulse and thrust, it actually manages to hit the exact same top speed. Because the motor is progressive thrust and the rocket itself is so light and gets lighter towards the end of the burn, it squeezes out enough oomph to get to Mach 1.46 at 840 feet. But in fact, if the rocket were made for the G138, it would be even lighter due to the shorter body tube so it would go even slightly faster.
Either would early eject at 200 ft/s, given its apogee would be at 20 seconds and those motors go only as long as 14 seconds, but that would still be at almost 9000 feet so a tracker would be absolutely necessary to be able to even think of finding such a small rocket.
Any thoughts? Suggestions? How could I hold the tracker in the nosecone securely enough and yet be able to remove it? Would the tracker survive the horrific acceleration of the H410? What sort of chute or streamer would survive such a fast deployment, yet not be too bulky? Where would I get skinny shock cord that would withstand the same forces that the parachute would?
No rocksim or openrocket file because the rocket is so incredibly simple: it's a 1-foot (or maybe shorter) 29mm phenolic tube. Fiberglassed on would be three 1/32" thick, 1" chord by 1.25" semispan carbon fiber fins made of 1x12 stock from McMaster Carr. Atop it would sit a Shockwave 29mm nosecone with a Beeline transmitter in it. Some sort of durable chute or streamer would bring it all down safely.
I figure that this will come in at about 6 ounces empty, so for max fun I plan on flying it on a CTI H410 Vmax and watching it disappear. And when I say disappear, I mean now-you-see-it-now-you-don't: according to Rasaero, its acceleration peaks at 166 g's 91 feet off the ground, and it hits Mach 1.46 at 350 feet off the ground. With a 3-foot tower launcher, even ignoring the gains caused by confining the exhaust gases, the rocket would go 136 ft/s off the tower.
An alternative motor (my personal favorite due to its impulse to size ratio, actually) that would allow me to further shrink the airframe is the Aerotech G138T. Despite the lower impulse and thrust, it actually manages to hit the exact same top speed. Because the motor is progressive thrust and the rocket itself is so light and gets lighter towards the end of the burn, it squeezes out enough oomph to get to Mach 1.46 at 840 feet. But in fact, if the rocket were made for the G138, it would be even lighter due to the shorter body tube so it would go even slightly faster.
Either would early eject at 200 ft/s, given its apogee would be at 20 seconds and those motors go only as long as 14 seconds, but that would still be at almost 9000 feet so a tracker would be absolutely necessary to be able to even think of finding such a small rocket.
Any thoughts? Suggestions? How could I hold the tracker in the nosecone securely enough and yet be able to remove it? Would the tracker survive the horrific acceleration of the H410? What sort of chute or streamer would survive such a fast deployment, yet not be too bulky? Where would I get skinny shock cord that would withstand the same forces that the parachute would?