AboutJames Bell Expertise I am a member of Tripoli Rocketry Association, and am certified to fly hi power rockets. I can answer questions anyone may have about design, materials selection, stability calculations, motor selection, altitude and performance predictions, and parachute and recovery options.
Experience I make my rockets from existing kits or parts readily made through commercial channels. I do NOT make my own motor propellants (they are challenging enough even for the companies that do this for a living), and I do not advocate making rockets using "typical household item" such as paper towel rolls.
Question For class i have been challenged to launch an egg 100 feet in the air, have it detach from its vehicle, then fall back to the ground safetly. I have decided to go with a model rocket idea, with the egg being in the cone, and the rocket made, obviously, by myself. My only concern is i have b engines to work with, which i realize i am going to need 4-7 of them to make the intial lift and get it 100ft. My concern lies in having all the engines fire at the same time. What can i do to ensure that all the engines go off at the same time, i heard of daisy chaining, cluster launch, but exactly how can i set this up? Your advice is appreciated.
Answer Greetings Jason -
I would suggest you visit the webpage I have set up for model rocketry ...
Scroll down to the PROGRAMS section and download the ALTPRED (altitude prediction) program. You can use that to see what would be the best motor to select. The installed database has all standard Estes motors, 1/2 A all the way up to D. You can even select multiple motors for clustering. Make sure you add in the weight of the egg in the overall launch weight of the rocket.
Once you have decided on which motor(s) to use, if you still need to cluster, I would suggest making a harness like I have in the PICTURES portion of the page (at the top). This harness works in PARALLEL, and NOT in SERIES. The term "daisy chaining" usually means in SERIES. In a SERIES setup, electricity fires one motor fires first, then the next. You definitely DON'T want that, as all need to fire at the same time. If you make a harness like I have in the picture, where the one positive and one negative connector are split into however many motors you have, the juice flows to all igniters at the same time.
I would also suggest you use a high-amperage battery system with at least 12-volts available. Although Estes motors usually fire on only 6-volts, you want to make sure they have plenty of power to ignite ALL the motors simultaneously.
I hope this answers your question, if not, don't hesitate to write back.
