Igniter, Electrical, Type II, BP

With the first test fire of MM-38 coming ever closer, a new type of igniter had to be developed

It has to be:

• Powerful
• Reliable
• Simple
• Easy to produce
• Compatible with ICBM-V2
• Small, so it can be inserted into the nozzle of MM-38
• Have Long leads, so that it can reach deep into MM-38
• Water resistant and externally non conductive
• Made from standardized parts

This facilitated a few key changed from the old type of igniter
These were made from 10cm’s of 1mm Nichrome Wire, forming a U shape with the ends bent 90 degrees to facilitate alligator clips, and a 1cm piece of sugar fusing being held inside the U by some ordinary kitchen wrap, holding it against the wire, and keeping it electrically separated from metal nozzles and such

These have been 100% reliable (outside of operator error), and have been used for every static test since Rocket 1, for a total of 10 static tests
They are incredibly simple to make, requiring no soldering, and with the only part requiring tooling being cutting the wire to length

It was clear to me from the beginning that this simply would not suffice for use in MM-38, since at most it could reach only slightly down from the nozzle, and would not guarantee ignition, and also torch the alligator clips if it did ignite

So the type II was thought up (Full name heavily inspired by the silly way in which the US Army names equipment)
It uses 0.5mm nichrome wire (as opposed to 1mm), 4mm Visco Fuse, and twisted 22awg insulated wire to connect it to the ICBM
This has a number of advantages

• 0.5mm Nichrome Wire is more economical, and also requires less current to get up to temperature, making ignition less reliant on battery condition
• The Visco Fusing is a commercial product, as opposed to sugar fusing which has to be made by me, and has been used in type I igniters, mainly because it was left over and not reliable enough for stand-alone ignition
  Visco is also made of black powder, as opposed to sugar / kno3, which is more powerful, and makes the igniters less vulnerable to moisture
• The 22awg wire allows the ICBM to be attached not to the nichrome wire directly (which is a bit silly), which in turn allows the igniter to reach in more deeply and into a smaller space, and reduces thermal stress and charring of the ICBM connecting wires

I have devised a simple 7 step process for manufacture of Type II igniters

And it sure goes:

The first 4 steps have been modified from Nakka’s process, because nichrome wire wont take solder, and it works great to connect it to ordinary wire

The covering in clingfilm (also called saran wrap) is both to keep the fuse closely in contact with the wire, and to insulate the wiring so that it wont short on metal rocket parts, it also helps keep moisture out thus improving reliability further

The end product is quite small, and easily fits into the nozzle end of MM-38

I also wanted to record this with a proper camera, because I find the spark very pretty, and wanted to show it in conjunction with ICBM-V2, so I did

While the soldering takes more time and increases complexity, the connecting wire can be quite easily reused snipping off a cm at the top and re-soldering some new nichrome wire
This of course can’t be done if its inserted into MM-38, since it will char most of the cable to a crisp, but since this is meant as a general purpose igniter, it still comes in handy

As it has only just been invented, it has yet to be actually used in the ignition of MM-38 or any other rocket engine I have devised, but when it is used in such a capacity, the results will be appended here

ICBM Upgrade

With great power comes great responsibility, so to take care of that responsibility I need to stay a good distance away from the great power.

For this I devised a marvellous and ingenious new invention: A longer wire

But that’s not all, I also uncovered the mystical ingenuity of connectors!

Joking aside, I have upgraded the ICBM system with a additional 5 meters of wire, and banana plugs to simplify logistics

A neat side effect consideration I took is that it is now modular in the way it triggers
Lets say I want to make it wireless trough the use of 2 HC-12 Radio Transceiver Modules
All I would need to do is make a sender box and a receiver box with some kind of banana receptacle, and this would just plug in place of the wire
When the signal is sent by ICBM-A, it enters the sender and is relayed to the inputs of ICBM-B, triggering the pyrotechnics
Alternatively, a completely different design of ICBM-A or ICBM-B could be developed independently and plugged in instead of either one, and the wire can be used for other potential devices that need to transfer a simple signal
The only limit is my limited imagination, and even more strained budget

I also needed something to test it with, and since it has been a while, I measured out 2.5 grams of granulated sulphur free black powder of my own make

I then wrapped this in a good amount of alumin(i)um foil, but not before ‘popping in’ a Type 2 igniter

This was then placed at the maximum distance this wire can allow

And then I turned the key switch of knowledge and held both of the science buttons

It is going to need allot more wire to keep a safe distance from MM-38, which at the moment I don’t have, but due to the magic of soldering or even the banana plugs extending it can be done indefinitely

That’s all