Introduction: Model Aircraft Rapier Ignitor

Those of you who have read my previous Instructable Rapier-Fuego-Retro-Model-Plane will know I promised to do an Instructable on my ignitor. Back when Rapier engines first became available they were supplied with fuses (mid you these could be more of a pain than worth it anyway), unfortunately that is no longer the case so other methods need to be found to light them that are quick and safe.

The best method is to use a hot nichrome wire as used in medical cauterers, these are really expensive and not always easy to get.

Step in The THREAD ZAP II, a cheap tool used in craft for cutting and sealing thread, the perfect starting point for your own powerful ignitor.

Step 1: Materials and Tools

Materials:

  • Thread Zap II
  • Thin Copper Sheet
  • 28swg Nichrome Wire
  • 2 x AA Battery

Tools:

  • Tin Snips
  • Small File
  • Pliers
  • 3d Printer or service

Step 2: Strip the Thread Zap

The thread Zap is a great tool but needs a few modifications and is not powerful enough for what we need.

  1. Remove the battery cap and keep safe as we will reuse later
  2. The outer body is coated in paint for insulation which we need to get rid of so scrape the pain off about 10mm of the rear of the Thread Zap
  3. Remove the tip ready for stage 3

Step 3: Modify the Tip

The wire in the standard tip of the Thread Zap is not long enough to reach the propellant in the rapiers and is also not replaceable.

  1. Grip the rear of the tip gently in a vice.
  2. Look carefully at the tip and you can see the ends are crimped over.
  3. Take a small needle file and gently file off the tips just below the crimp exposing the holes in the tubes
  4. Test your Nichrime wire for a nice fit
  5. Take a 1" pice of wire and bend to make a new tip that will have about 1/2 inch to go into a Rapier engine and the ends into the tip tubes.

that's it for the tip you now have a longer and easily replaceable tip

Step 4: More Power!!

We need more power to get the oompf we need so lets add a second battery to the Thread Zap.

  1. Download the attached stl or open scad file
  2. Print in PLA

You should now have a nice tube with an internal step at one end, a thread at the other and an internal groove down the length.

Step 5: More Power 2

In order to get the power from the extra battery we need to run something down the 3d printed parts.

  1. Find some thin copper sheet, mine was what they use to keep slugs out of plant pots.
  2. Cut a strip as wide as the groove in the 3d printed tube and a bit longer
  3. Fit this in the groove and bend over the ends to hold in place, make sure there are no sharp bits sticking out.
  4. Push the stepped end of the tube over the Thread Zap making sure the copper is in contact with the area you scrapped off the paint.

Step 6: Final Touches

Your almost there drop in 2 AA batteries , screw on the endcap you saved at beginning and head off to the flying field

Caution: that tip get seriously hot now so always keep the cap on when not in use.



Step 7: Bonus Plan

As a bonus here is another very simple aircraft that flies great as a hand/catapult glider by adding a Rapier engine under the front 3rd of the wing.

Balance point should be just behind the first joint.

Have Fun and Happy Smoke Trails

Comments

author
Lostelements (author)2016-06-19

I love flying Estes rockets but please neve try and light one of those in your hand. Rapiers are very slow burning 20plus seconds and generate mostly smoke. Estes are black powder and burn almost instantly and would seriously hurt

author
gm280 (author)Lostelements2016-06-19

Not sure if you were addressing your comment to me or not. But I never ever tried to ignite any rocket engine in my hand. All my rocket engines were installed in a rocket and sitting on a launch pad and safety was the upmost important issue. I even lengthened the typical few feet of cable from the control switch to the actual launch pad for that very reason. The usual Estes set up was a few feet of cable, I easily had doubled what they sold or even longer.

author
Lostelements (author)gm2802016-06-19

Hi, not specifically at ypu but i was just concened somebody might. Your right longer the better for rockets especially when you get above D size,gives you a better view of the lauch as well

author
gm280 (author)2016-06-18

This brings back memories when I was younger and use to launch rockets. Usually I didn't buy the Estes igniters (didn't have much money) and simply made my own. Since I made my launch control system as well and was using an automotive battery, I easily could use a single strand of wire from most any stranded copper wire for my igniters, and when I hit the button, it would glow red hot instantly. And that would always ignite the propellant in the engines. And a cardboard book type match, used to hold the copper wire in place, always helped out too.

About This Instructable

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Bio: Ageing geek, maker and Steampunk fan with an all round thirst for fiddling with things.
More by Lostelements:Model Aircraft Rapier IgnitorRapier Fuego Retro Model Plane
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