Flying high power rockets safely means also spending some thoughts on a state-of-the-art recovery system. The introduction of electronic altimeters and timers has brought a big improvement but also some new problems: The relatively low output current of most devices asks for a low current igniter.

For years, flashbulbs have been used to ignite ejection charges, but I have never felt good with them. Flashbulbs are unpredictable both in their function and in their ignition current. I have seen flashbulbs showing continuity that would not fire. I have seen flashbulbs going off at continuity check and we also have heard about some bad accidents when flashbulbs set off ejection charges prematurely.

So I was very curious when I saw the SafeEject ejection charge holder of SpaceTec for the first time and had to get one immediately.

The charge holder is machined from aluminum and anodized red. It is 40mm (1 ½") long and 15.8mm (5/8") in diameter and can take up to 3 grams of black powder. SafeEject is designed for use with industrial electric matches (DaveyFire & HiRMI) and provides a positive seal around the leads to prevent gas leakage.

I specially like this feature because it prevents corrosive combustion products and pressure peaks from reaching and damaging the sensitive electronics, one of the main reasons for electronics failures.

I found the preparation of a charge using the SafeEject to be very simple: The head of the igniter is bent back to make sure it is inside the black powder also on small charges. After having twisted the uninsulated ends of the igniter leads for safety, the igniter is inserted (wires first) into the charge container and through the bore for the igniter.

It is pulled completely down and the wire is bent down into a groove that is machined in the bottom of the container.

The closure cap is bolted on the bottom end of the container using a special hex-headed closure bolt. The igniter leads have to sit in the groove when the bolt is tightened. No tools are needed here, tightening by hand is enough.

Mounting is done with a small hex head cap screw.

The correct charge is filled using the provided 1ccm (1g) measuring spoon.

It is capped using a little protective wadding and a small piece of masking tape that is pulled down into the charge holder using the contained wooden dowel.

While this works very well when done with care, Juerg Thuering from SpaceTec showed me an even better way to contain the charge:

1. A small piece of paper is wrapped round the dowel and taped with some masking tape. (Figure 1)

2. A second piece of masking tape is put over one end of this paper roll then. (Figure 2)

3. and after that, the whole thing is wrapped with one layer of masking tape again. (Figure 3)

You get a paper cap that fits tightly into the SafeEject container and won't let black powder leak out of it. This cap is simply pushed down into the charge container and the charge is ready.

Figure 1

Figure 2

Figure 3

SafeEject can be easily mounted as shown.

Optional altimeter bay mount shown.

The seal around the leads is good enough however to allow installation of the charge directly through the wall of the electronics bay.

I personally like this feature a lot because it makes preparation of the rocket much simpler.

Pictured is my modified ARCHER that uses two SafeEjects to fire Drogue and Main chute out of the same end of the rocket.

I have used SafeEject for almost one year now and found it to be 100% reliable, simple to install and after all: safe!

Electric matches don't go off because of static electricity, instead they work very reliably!

Because of it's dimensions, SafeEject fits existing constructions like PML's CPR and provides extra protection for your expensive electronics.

SafeEject is available also in two additional variations:

1. SafeEject II is designed for redundant systems using two separate matches.

2. SafeEject EX is 24mm * 70mm large, uses two matches also and is designed specially for large Level 3 rockets that need both, bigger charges and extra safety through redundant electronic systems.

Using two matches that are fired by different systems on the same charge eliminates the potential problem of both charges going off at the same moment and over-pressurizing the rocket.

The SafeEject ejection charge system is manufactured by SpaceTec and sold in the US through rocketry dealers exclusively. Retail price is about $25.