AboutDave Landgraf Expertise I will be happy to take on questions about low-power rocketry in general, including rocket design, operating characteristics of blackpowder motors, low-power motor selection, rocket construction, aerodynamics, parachute and streamer duration competition, boost glide (and a little rocket glide), egg loft, altitude competition, and scale competition. I can help you with Barrowman stability calculations, but I am not a rocksim user. I know the basics of mid-power rocketry and small composite motors but I don't fly them much (I'd rather stretch my money by sticking with low-power). I believe I can explain many concepts in a way that just about anyone can follow (and maybe even over-explain?). I absolutely do not mind "newbie" questions one bit; the only bad question is the one you don't ask!
Experience I have flown model rockets for some 40 years, including a few early years of NAR competition. I have been active at the local club level as well as in the NAR. I enjoy designing and developing unconventional designs (the kind of thing you look at and say "it won't fly!").
Organizations National Association of Rocketry
Publications Model Rocketry (magazine)
Education/Credentials I am an aerospace engineer who has worked professionally in the field for over 30 years. I have worked often with local school, church, and scout groups to lead introductory build-n-fly sessions.
I still have a similar question. Estes claims that to ignite an Estes E engine (vs an Estes A,B,C,D), you need to upgrade your launch controller to an Estes E Controller. What is the difference- more volts? Don't these single use motors use the same igniters? Could I use the original Estes Electron Beam igniter that I use for all other engines?
Answer Hi Chris,
You may not realize it, but you have asked sort of a "trick" question.
The other answer (about Aerotech composite motors with different igniters) is correct...for Aerotech motors.
However, there are also Estes E motors available, and I believe your question is more directed toward that type?
You are correct that the larger Estes E motors are made of the exact same materials as smaller Estes motors, and could indeed use the same ignition hardware and power supplies. The big difference is that the weight of propellant that is loaded into the E motors is heavy enough to put these into a different safety class. These require a greater set-back distance between the launch pad and you (and any observers present at the launch).
The set-back distance (some 15 feet for low-power motors, and I believe 30 feet for mid-power motors) is supposed to identify a safety boundary to protect you in case of catastrophic motor failure on the launch pad. If that thing blows up (which RARELY happens with these motors) you will be far enough away that any fragments or blast pressure will be mostly dissipated before they can reach you. The set-back distance is the only change; you use the same igniters, the same clips, the same battery power (for Estes igniters), and the same everything else.
So, take the advice seriously and do indeed remain the proper, safe distance away when using E motors. I find that it is a little easier to see the model rocket's flight when you are standing a little further away.
Estes sells a different launch controller for these big motors because longer lead wires (the wires that reach from the hand-held control unit to the launch pad) cause more electrical resistance and reduce the electrical power delivered to the igniter. Because these wires are longer, you need to use thicker wires that have lower electrical resistance to maintain enough volts and amperes at the igniter.
If you are talented with your hands and understand electrical devices, you can disassemble your Estes launch controller and replace the 15 foot leads with a 30 foot length of heavier wire. One type of wire that works well (and is fairly easy to find) is speaker wire for stereo systems. Find yourself a small spool of heavy-gauge wire and make your own launch controller modifications.
One other safety note: You should also check to see if your E-powered model rocket has larger launch lugs. These are intended to be used with a larger diameter launch rod, which should also be longer. For mid-power rockets I recommend you find a 3/16ths inch steel rod (or 1/4 inch rod, if your launch lugs are big enough) that is at least four feet long. Check your local hardware stores for what they call "round rod"---it is often stocked in bins with threaded rod, bar stock, aluminum angle stock, and other specialty metal shapes.
I hope that information helps. If you need more help, feel free to ask some more questions or to join in at The Rocketry Forum, http://www.rocketryforum.com/, or at Ye Olde Rocketry Forum, http://www.oldrocketforum.com/. Both are free to join, and there is a ton of experience and advice available.
