Launcher Requirements

I'm working on a project and I'm wanting to know the requirements. I have visited the Tripoli website, but am looking for a bit more clarification/opinions as to what I'm attempting.

The safety requirements for launch controllers state it needs to be a removable "key" inline with the launch circuit. If a wireless launch controller is built, would the removable key only need to be located at the RCO position, or would there need to be a removable key located at each wirelessly connected module?

Thanks in advance.
Cosmo

There was not much room in my wireless remote for a 'real' key. I went with a 'simple' key.



Tony

Tony,

I'm thinking of a simple key like that in my master controller, but do you need something like that on the receiver end? Or is just one key satisfy the requirement?

I placed a normal key switch in the transmitter box too. It gives me some peace of mind when I'm out launching N's +. I'm not sure if it's "required".

Tony

Hi Tony. Talk to Bob K he knows the req and regs inside out and out. I bought the same unit haven't had a chance to mess with it but it looks like a workable item. PM Bob K he knows the gig

There are no separate or specific rules for wireless firing systems in NFPA 1122, 1125 or 1127, nor in any TRA or NAR extensions of them.

While removable "key" is required for the launcher circuit, but it do not need to be a key switch. What Tony did withh is wireless firing unit is fine and that is the same solution Estes uses with their wired launchers.

There is no removable "key" switch requirement for the wireless relay box, however a shorted coaxial plug tethered to the wireless relay box also is fine insurance.

Tony's firing unit uses employs a rolling code "key" which is continually changing so the code itself acts as a "soft key".

IMO any simple uncoded wireless relay box is not safe and should not be used, nor should any homebrew wireless relay box that applies full power to the firing relays during initial turn on. METRA had one, and at a NERRF when a wireless relay box had to be rebooted during a launch by a pad manager, it fired a high power rocket located 15 feet away. Not good.

Bob

Bob,

Thank you for the information. I was thinking of "key" like what Tony did. I'm trying to build a wireless launcher and want to use a coded "soft" key for the actual launch pads. The remote pads require 2 "arming" signals. The first is a physical switch at the pad you arm after setting up the rocket. When the switch is active the pad would be armed after a 60 sec timer expires. The second is to receive a valid arming command from the master controller. Both of these would be required for the pad to activate the circuit to launch the rocket.

I know I'm working on building a home-brew system, but I do want it to be very safe. Thanks again for all the suggestions.

Jesse