TOPIC: Lighting Rapiers on the Flying Field

I thought the same Roger, however after some very basic testing ( switch it on and hold the wires between my fingers!) up to 30 seconds there is only a slight warming of the wires which is only noticable after 20s. Since every motor I have used it on has ignited within approximately 3 seconds I'm happy that the current wiring is up to the job.
Now back to the building board!

While we are on the subject of igniters again. Here's something I've been working on these last weeks. Thus far this is about the best version. The box is laser cut and the battery connect to the style of plug that can go in a mobile phone charger. (The next version will be a little skinnier.)
I was able to find some flat nichrome. This is 0.4mm x 0.1mm and it makes a better 'hairpin' and will, I hope maintain that shape as it gets used.

I'm glad this topic has resurvaced. With the development of our TSP 'Spectre' motors, which we hope will be popular on the flying field, we really need a readily available electic ignier that is simple, robust, reliable. Oh, and inexpensive.

As this thread (and other discussion threads) have shown, this is not as easy!
I have been using modified 'Bovie' medical cauterizers and Cord Zaps for some time, but with mixed results. The problem with these is that the two AA nominally 1.5V batteries they come with don't apply quite enough voltage and therefore amps to get the sort of glowing tip that ignites ALL motors, even recalcitrant ones. Especially if you use a more robust 26 SWG Nichrome element in lieu of the usual 28 SWG.

As an aside: Nichrome wire also seems last longer than Kanthal.

My most recent three-cell and four cell igniters are horribly crude, but they are effective, and have shown to my satisfaction that 3 AA cells are adequate for most purposes as they ignite motors, even in a stiff breze (which can cool the element), and tend not to melt the element, which can be a problem with four cells!



Above: my 'proof of concept' three and four cell igniters gave good service at the last Old Warden meeting. I now need to make a refined 3-cell version that I an not ashamed of!

A further stimulus to this is seeing the estimable Marcin's very posh igniter in the latest postings on our 'Flying' thread.

Here it is:



Above: Marcin's igniter. I'm not sure what he has based this on (a small metal-bodied torch perhaps?) or how he made the mount for the element. I note he uses four small (rechargeable 1.5V?) batteries which give a nice healthy glow!

Marcin says it's very effective. Well, it sure looks good and I've asked Marcin to share how he made it.

Watch this space!

The igniter is made of an aluminum tube (left over from some printer toner), a switch, screwed electrical connectors, wires, and two 2x1 mm brass tubes. The igniting element is a 0.35 mm kathal wire. The bottom and head are printed on a 3D printer. The fuse is 100% effective. It is intentionally powered by quite large and heavy R14 batteries, but in the future the igniter will also power the charger of models with a capacitor drive. The batteries are soldered to ensure current flow.

Igniter is as simple to build as possible. Just find a pipe (alu, PVC, paper, composite) with a diameter that matches the diameter of the cell. I can design 3D files and send them to you. 3D printing is not a problem today, the rest is simple.

This is my latest version. The box is laser cut from MDF. It's much the same as the version I put up a few posts back.
There's a cover, removed for clarity for the underside.
The cable to the right is the charging cable. One must disconnect the battery, connect the charging cable to the battery and the other end of the charging cable goes in a mobile phone charger.

The battery is a 3.7V 18650 Akku, 3200mAh which, so far seems to be adequate.
See below for battery link:

18650

The heating element is made from 'flat' nichrome 0.4mm wide by 0.1mm thick. This folds quite nicely into the familiar 'hairpin' shape. I start with a piece 65mm long and fold it in the middle. The two ends are each folded back 5mm or so and then mounted in the terminal block.
I found a German supplier:
Zivipf for the flat nichrome wire.