In what is possibly a first, the MIT Rocket team have successfully tested a fully 3D printed solid rocket motor. The motor which included everything bar the propellant was printed from Nylon.
Be interesting to know the cost, let’s say vs a hobby motor of the equivalent size.
Check out the video below and read the full write-up here.
Video Caption: Using Markforged Onyx Nylon a 2 piece, completely 3D printed rocket motor was fired for the first time by MIT Rocket Team on April 21.
Without the generous support of Markforged this project would not have been possible.
12″ diameter (304.8mm), 2 Bates grains, 260lbs (117kg) of propellant!
Be interesting to know the thrust and chamber pressures achieved in this test, they seem to have figured out any grain cracking issues that could arise and over pressurize the motor, looking forward to seeing more tests of this size in the future!
Video Caption: 2 grains 12×20
260 pounds of propellant
Motor by Rick Maschek and Eric Beckner
Video Caption: A 4″ (100mm) ‘K’ impulse 2-grain sugar motor. The airframe was made from salvaged and scrounged materials from other rockets. The propellant was KNSB with a 1″ (25mm) core. Launched November 5, 2016 from the FAR site, Mojave Desert.
Robert Steinke of SpeedUp provides an interesting update on estimating the performance of the Cesaroni Vmax motors, to find that they are probably under expanded.
For the Moment of Inertia rocket I’m going to be using a Cesaroni Vmax motor. In particular, the 29mm 3-grain H410. 410 Newtons is a lot for this size motor: 42 kgf, or 92 lbf. It makes you wonder, how do they get that much thrust out of such a small motor? It has to have either a high chamber pressure, a large throat, or both.
Chamber pressure came out to 870 psia, and sure enough, the nozzle is properly expanded for one and a third atmospheres.
The place where I launch is at 5000 ft elevation, about 0.83 atmospheres ambient pressure. Proper expansion would be a nozzle area ratio of 8.8 instead of 6.25. That would mean extending the exit diameter from 0.75″ to 0.89″. It should get 1.6% more thrust, or 417 instead of 410 Newtons.
Continue to read the full update here.
Video Cation: An 89mm ‘M’ impulse 4 grain KNSB sugar rocket motor test at the Friends of Amateur Rocketry facility in the Mojave Desert, California on September 3, 2016.
Robert Steinke of SpeedUp has posted a new update, building a Mach breaker rocket
I’m starting on an extra little side project. I’m going to build a Mach-breaker rocket using the Cesaroni 29mm H410 Vmax motor. Here’s a picture of the basic layout.
I imagine the fist question I’m going to get is, “Why did you choose tube fins? Tube fins are high drag. Don’t you need low drag for a Mach-breaker?”
Read the full update here.
Worth a read for those interested in the physics of it all.