I agree the wire support for the empty tubes is an elegant way to support the Q2 igniters in the tubes.
Since I rarely use the tubes myself I've never had cause to worry about how to support them as they Q2 igniters work the same as bare nichrome on my coiled clip supported pads.
It is however my contention the cardboard tubes cause more problems then they solve as far as misfires are concerned because we can't see what's going on below the edge of the tube. If the model sits down of these things to far or is pressed down to hard bending the wires causing them to touch inside the tube you don't know it until the model doesn't take off. I like having the entire external portion of the igniter expose to view so it's possible to tell right away if we've created a misfire short durning model installation.
Better yet is night before igniter installing in the motors using the old tape and wadding ball method. This simply does away with shorted wire misfires.
(I remove the glass bead from Q2's for this type installation) they work just fine.
Mark, that's more or less the may most Drag Race systems are set up tapping a single power freed X number of sets of equal length clip whip leads. Jim's 3 arm launcher could just as easily be 4, 6 arm depending on the power supply and location of that supply with repect to the launcher or relay.
Generally I include a two pad Drag race option on most of our Rack system set-ups just by adding a clip lead to the back side of our pad splitter.
I've been toying with the idea of adding a pair of swing out arms on my little micro everyday pad to allow a 2 or 3 model drag race option to it's abilities. the Only hold up has been looking for an elegant way to wire these arms with concealed wiring.
Blackjack: I don't understand: You have all the tools and skills need to produce a pad just like mine. wood, plastic or aluminum these materials are the only difference. The only reason I use aluminum over wood is for longevity. Sure it's a little harder to get "cheap" then wood but with a little digging and dumpster diving we can come up with loads of the stuff from scrap junk thrown away all the time. ie Old street and parking signs are usually .063" or .080" aluminum these days
I think I'm gonna do a complete build thread on that little flat plate launch platform so you guys can see just how easy it was to produce, I mean it really is one of those anyone can do it things. I'll go so far as to use an unpowered mechanical hand drill, hacksaw and hand tools for all the work. A 1/4" powered drill and sabre, scroll or band saw makes it a little quicker and easier but not necessary. All the finishing filing and sanding are done by hand anyway.
I do think your motor casing DragRace launcher is pretty neat!