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-   -   Radio ignition system (link) (http://www.oldrocketforum.com/showthread.php?t=16871)

blackshire 10-06-2017 10:23 AM

Radio ignition system (link)
 
Hello All,

While looking for other items on eBay, I just came across the store page of Bundaberg Fibreglass (Damian Bundy), an Australian vendor of music- and hobby-related electronic devices and fiberglass (or fibreglass; the British usually call it "glass fibre") vehicle accessories such as air scoops (that's an eclectic product selection, to be sure... :-) ), and:

They sell, for $31.14 plus ~$12.37 postage (U.S. dollars), a coded FM radio-controlled, model rocket remote ignition system (see: http://www.ebay.com/itm/Remote-Mode...WEPK s&vxp=mtr ), which has a range of over 50 meters (165 feet). Now:

For people with spinal problems that make it impossible to lean back to look up and follow the rockets' ascents (I'm in this category; I have an increasingly quadrupedal stance, which I would otherwise welcome, but it is very troublesome--and painful--in my current form), such a device is a godsend! Even for those who are not so afflicted, being able to watch launches from a greater distance--and thus "from the side"--would *literally* provide a new perspective on the hobby, by enabling all flight events to be observed against the local terrain, the horizon, and the "lower sky" background. It would also be beneficial to radio-equipped payloads (transmitting instruments' telemetry, audio, video, etc.), because the simplest and most practical model rocket-borne antennas emit more RF energy broadside to the rocket's body than straight down to the ground.

Dugway 10-06-2017 02:46 PM

I'm planning on building a couple LPR pads using LiPo batteries and the Eggtimer WiFi Switch. He claims to have tested them to 200'. Use your phone to (securely) launch your rockets, no more wires for the kids to trip over.

astronwolf 10-06-2017 02:59 PM

Quote:
Originally Posted by Dugway
I'm planning on building a couple LPR pads using LiPo batteries and the Eggtimer WiFi Switch. He claims to have tested them to 200'. Use your phone to (securely) launch your rockets, no more wires for the kids to trip over.

How will your WiFi switch achieve all of Rule 3 of the NAR model rocket safety code?

Ignition System. I will launch my rockets with an electrical launch system and electrical motor igniters. My launch system will have a safety interlock in series with the launch switch, and will use a launch switch that returns to the “off” position when released.

blackshire 10-06-2017 03:05 PM

Quote:
Originally Posted by Dugway
I'm planning on building a couple LPR pads using LiPo batteries and the Eggtimer WiFi Switch. He claims to have tested them to 200'. Use your phone to (securely) launch your rockets, no more wires for the kids to trip over.
Yes, that should work. Cellphone-activated bombs have been used for nefarious purposes (dialing the "receiver" phone's telephone number set it off), so a similar set-up using WiFi should work for this far more positive and happy application.

blackshire 10-06-2017 03:32 PM

Quote:
Originally Posted by astronwolf
How will your WiFi switch achieve all of Rule 3 of the NAR model rocket safety code?

Ignition System. I will launch my rockets with an electrical launch system and electrical motor igniters. My launch system will have a safety interlock in series with the launch switch, and will use a launch switch that returns to the “off” position when released.
I see no insurmountable problems here. The WiFi radio system ignites the rocket motor electrically, by passing current through an electrical igniter; the radio link merely takes the place of ignition lead wires between the launch controller and the rocket on its launcher, and:

The safety interlock can also function over a radio link. A relay that closes the launch battery/igniter circuit at the launch pad doesn't activate until the properly-coded radio signal, received by the receiver, triggers this function. When the radio signal ceases (or its coded "message" changes, when the launch button on the hand-held transmitter is released), the relay's coil is de-energized and its contacts (in the launch battery/igniter circuit) go open, preventing any more current from flowing in that circuit (if the igniter failed to burn through and physically break, that is). Also:

The length of time that the relay contacts are held closed (to allow current to flow in the battery/igniter circuit, to launch the model) could be programmed via software. As an additional safety feature, I would include a "pull-out" plug and jack in the battery/igniter circuit (a mono audio plug with "shorted" contacts [under its threaded-on cap] would suffice for such a plug). In the event of a misfire, after waiting one minute, one could walk to the launcher and pull out the plug (which could have a 15' length of brightly-colored string tied to it and laid out on the ground extending away from the launcher).

georgegassaway 10-06-2017 07:58 PM

FWIW - I got a wireless 4-channel fireworks controller for $18 from China:

http://www.ebay.com/itm/Fireworks-F...34AAOSwa~BYUqlN



Have not done much testing with it yet, although the range seems better than any I have used before. In large part since the ones I used before had no antenna on the transmitter, while this one does.

Need to add output wires with micro-clips. The receiver has 4 outputs, each one with an LED that lights up when "fired".

Technically, no removeable safety interlock key.

For this one I figure a good approach will be to wire up output #1 and #3 in series so that both buttons (1 and 3) have to be pressed for launch. Or to require two hands (without using a holder or table), #1 and #4 for one output set. In the past, I had one with a keychain remote where I pressed a red button to "arm" the system for 5 seconds, then pressed a blue button to fire... within that 5 seconds. I used it mainly for launching R/C Rocket Boosted Gliders by myself for practice flights. This one does not have that 5 second arming trick, so if I want to use it launching RBG's I'll use it with the outpits for #1 and#3 so I can press both with one finger.

I will note that for my personal launch controllers that DO have a safety key, the key is TIED to the control box so it does not get lost.

For the real tinkerer, then crack open the TX, gut it , remove the button leads, and wire up your own button, safety interlock key, and new LED since the old one may not be practical to use.

The receiver uses four AA Batteries. So,pretty much limited to Solar ignitors or low-current ignitors (it comes with a few e-matches, and the price of 100 e-matches are really cheap!). Not for copperheads, Firestars, or other higher current ignitors orclusters. If I wanted more amps, I'd install NiMH (or nicad) AA's that deliver more current over a short than Alkalines. If I wanted even more, I'd use a 7.4V (2S) LiPo with a 6V Voltage Regulator, as the 8 volts from a "7.4V" Lipo might fry the circuit. Or use it to trigger a relay.

A problem with the wireless systems, as well as relays, is no good way to check continuity. To solve that, I made up a continuity checker box for the pad, with a toggle switch to go from continuity mode (not armed), to armed mode (no continuity). Because there was no safe way that I found for doing it otherwise.

blackshire 10-06-2017 10:01 PM

Thank you for posting that, George. There's even a 12-channel one (see: http://www.ebay.com/p/Wireless-12ch...5.c100005.m1851 -
it's listed at the bottom of the page you posted) that's only $36.59; w-a-y overkill for the average individual model rocketeer's wireless ignition needs, but perfect for club or group launches. As you mentioned, I'd go with a relay ignition system, as it could use very short ignition leads at the pad, which would have *very* little voltage drop between the battery/batteries and the igniter. (Centuri's Servo-Launcher [see: http://www.ninfinger.org/rockets/no...a/72cen052.html ], which was electrically similar--it used a long length of pneumatic tubing with a plunger-type pneumatic ignition button at its far end--needed only *two* Photo-Flash "D" batteries [alkaline "D" batteries could be used instead today] to do the job that up to *six* Photo-Flash "D" batteries [as the catalog citation says], acting through 15' igniter leads, would be needed for if the Servo-Launcher had had ordinary igniter leads.)

tbzep 10-06-2017 10:19 PM

I've had one just like George's for a year or two, but like him, I haven't fooled with it much. I haven't launched anything with it. Too many jobs, too little desire to do anything but sleep when I have a few minutes of down time these days.

blackshire 10-06-2017 10:25 PM

Quote:
Originally Posted by tbzep
I've had one just like George's for a year or two, but like him, I haven't fooled with it other than to check to make sure it worked. I haven't launched anything with it. Too many jobs, too little desire to do anything but sleep when I have a few minutes of down time these days.
Having unwillingly embarked upon a new "career" of creating employment for clinics, therapists, and doctors, I can relate. :-) I no longer have a flying field, since the owner of the horses (in whose pasture I launched rockets) died, but this situation may not always be the case, and the 4-channel wireless ignition system is certainly cheap enough to get even as a JIC "Just In Case" item...

georgegassaway 10-07-2017 12:04 AM

2 Attachment(s)
FWIW - I googled and found a thread from 8 years ago, that mentioned the two wireless systems I used before. Message 1 mentioned the new one i'd come up with. Message 2 had info on the original I had, which was nice till it died after 2-3 years. Neither one had great reliable range, sometimes they'd test over 200 feet but often it was no more than 100. Indeed I got very frustrated with the newer system as at times it would not work farther than 60 feet, a big reason why I stopped using it.

This new fireworks based system.... I got a range of about 80 feet indoors with the antennas DOWN. Still haven't gotten around to doing an outdoor extended antenna test.

http://www.rocketryforum.com/showth...cial-components

From the link above, a schematic for the continuity checker box used with the Linx receiver:

http://www.rocketryforum.com/attach...=1243467948.jpg


And a photo of my first one, keychain remote resting on the left lower corner of my R/C transmitter, the system’s receiver and relay box (white), and the continuity checker box (black)

http://www.rocketryforum.com/attach...=1243468474.jpg


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