Glad Youre interested Ken. Now, first things first; I was introduced to this setup by TAP member Juergh Thuering (Tripoli Prefect of Switzerland and Swiss Team Ariane, TRF member as well) some months ago: that's why I referred to this tech as *my* (in the previuos post).
When I asked him, Juergh pointed me in the following direction:
https://www.argoshpr.ch/Images/Ariane020623_IgnitionBoard/P6220048.JPG
The picture shows the inside of the Ariane main airframe (PML 11.4"); BTW the red-anodized boxes screwed to the bulkhead are totally pyro-free "ARRD": they're servo actuated and have been designed, manufactured and throughly tested by Juergh in a great number of flights (EMR2, Electro-Mechanical-Release or something like that).
As You can see two channels are mounted inside the tube and they hold the black powder canisters; the inside channels (IC) bring the canister ABOVE the main deployment bag: this way no gasses have to by-pass it (as if the charges were to be fired from the bulkhead).
An important issue about this setup is that the fit between the main dbag and the airframe has to be LOOSE for the drogue/pilot to succesfully extract the dbag itself.
That may become more of a challenge in smaller diameter airframes (not that much of a concern in 7.5" tubes and larger but I never dealt with them). Some mods may be required: in my latest project, for istance, I had to fit a Rocketman R9CXP/R12C (roughly the same volume since the ProXP is thicker) into a 5.5" airframe; Rocketman reccomends a XL dbags for both but that bag is 6.5" in diameter and it fits super-tight even without the internal channels! Solution was to modify the XL dbag bringing its diameter back to that of a Medium-sized Rocketman bag (around 4.5"); since the XL is reasonably longer, careful packing of the chute prooved that the extra length could compensate for the reduced diameter, providing the necessary loose fit WITH the channels installed. Or You could simple switch to the previous dbag size (using a L instead of a XL,
) if You see You are still able to pack the 'chute in it (and if You are confident that the 'chute WILL deploy successfully THE WAY You packed it). I want to repeat that this is necessary in smaller diameter airframes. Nonetheless the Ariane LRB and SRB (3" (sure) and 4" (not sure)) use the same setup with one channel only; here are the pics:
https://www.argoshpr.ch/Images/Ariane020623_IgnitionBoard/P6220068.JPG
https://www.argoshpr.ch/Images/Ariane020623_IgnitionBoard/P6250007.JPG
In the main airframe (and IF space isn't an issue) the channels are two because they hold two canisters for redundancy; You may think to replace the two channels with a single canister holding two e-matches (or with a single channel holding two canisters); consider however that using two channels helps with the fit: the bag is held by the channels and the friction is greatly reduced as it is pulled out (less surface contact). If using one channel only, the bag will contact a larger area of the airframe itself (and it will be pulled out asymmetrically).
Building the channels may represent some unnecessary extra-work; You may think that in larger diameter rockets the charges fired from the bulkhead have plenty of room to by-pass the bag and eject the nosecone: that is right but the channels make for a cleaner and safer setup and they're definetely worth it (I would have done anything in my power to avoid doing that extra job but ended up with no better and/or safer solutions). Since the bag has some length of shock cord between the shroud lines and the bulkhead it may seem possible that the charges push it forward in the airframe while by-passing it, resulting in some kind of internal tangling and 'dirty' setup.
I got carried away: sorry for having been long; hope this may help You develop better solutions; I'll post some pictures of my channels in the next messages.
Ciao,
Giacomo