I fly lots of Midgets. I think you'll find, with the original K-40,
that trying to using rings instead of a full-length 1.75" sleeve (of
spent casing) is more trouble than it's worth. Just put the T booster
in a spent casing without cutting it into rings. We're talking maybe 5
grams of difference. Not enough to be worth the effort.
Also, you'll find the motor cases aren't perfectly round and centered,
or exactly the right size. You'll be more likely to get a mis-aligned
(canted) motor using two rings than using a full length sleeve.
For the sustainer, the pickin's are pretty slim. Either a 1/2A3-4T
(sleeved) or a sawed-off A8-5.
Here's a couple of my latest incarnations. This one is nearly an exact
clone, but I lengthened the booster a tad to accomodate more sustainer
motor overhang, to ensure straighter coupling.
Here's a slight upscale using Quest T-30. Uses full sized, standard
18mm motors. No sleeves or saws required :)
BTW, I got some pyrogen. This weekend, I plan to put to use the
research you did on staging with pyrogen.
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG
Very nice Midgets and great paint as well.
OK, so the 18mm rings are not the right way to go, huh? Oh, well.
I just figured it was going to be kind of a pain to friction fit both the Ts
into the 18mm adapters and then the 18mm adapters into the BTs, meanwhile
trying to keep the 2 T's properly connected for staging. Of course, I guess
I could just glue the adapters to the Ts, turning them into 18mm motors, and
stage them as such. Just means I have to cut new adapters for each launch.
I know A10-0Ts are OOP - but it looks like they're no longer certed.
Stupid... (I think once certed, they should stay certed - at least for
sport launching - unless there's a "recall").
Hey! didn't think anyone was listening to my machinations about
pyrogen-coated nozzles. :^) I'll certainly be interested to hear about
your experiences. What pyrogen did you get? I used Magnelite.
Recently ordered a bunch of powdered metals and other such goodies so that I
can get some experience with pyrogen and igniters.
...The Bit Eimer NAR 84054 L1
"My goal in life is to be the kind of person my cat thinks he is"
Thanks. I spend too much time sanding and painting.
I've tried using motor cases to cut engine blocks from, but the rings
are usually too small, and need to be built up (few wraps of tape)
before they fit well. It was easier to just use real centering rings.
(Of course, if it's two in the morning, and you're out, then the
spent cases are a God-send :)
In trying to use these sawn rings as adaptors, I'm afraid you will find
yourself building up the motors to fit snugly in them, then building
the rings up on the outside to fit in the motor tubes, then getting
frustrated with all the effort required. Sawing off the case
at 1.75" and sliding the T motor is a lot easier (IMHO).
Buzz McDermott gave me some original ~1972 adaptors which look
like unused motor cases, but include engine hooks, on the inside
IIRC. The hooks are flush with the ends. Basically, they turn T
motors into S motors, but are reusable. Of course, the adaptors
still need to be friction fit into the motor tubes. I haven't
gotten around to playing with them yet...
FWIW, these variants just use the T motors as is, without
That's the easiest way :)
That's the tradeoff. Either make the extra effort to cut new ones each
time or make the effort to friction fit the T's into the adaptors.
It helps to just cut a bunch at once and put them in your range box so
you always have one. Also, if the motor slides in and seems to stick
well without tape or glue, then you can maybe reuse that one. In fact,
using these adaptors, I just made up a bunch of syntho-S motors and put
them in my range box, right next to my few genuine S motors.
Don't get me started.
I got some from a friend. I'm not sure he's licensed to sell
pyrogen, so I won't mention his name, JIC.
I'm already spread too thin with the hobby, without adding yet another
aspect of it. But I'd like to play with it someday.
My latest idea is to see if I can put an Aerotech delay into an Estes
booster motor and see if the delay will light when the BP burns thru.
We could make our own oddball motors that way. C6-1 D12-14 B6-9
And it's no more involved (read: dangerous) than assembling a 24mm
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG
I got one out. Pic and scans here:
Looks like it's best for single stage, but could be used for staging. The hook
is flush, but on the outside contrary to what I said earlier. The user must cut
a shallow slot for it to fit in.
Basically, the challenge will be dealing with the ends of the hooks where the
two adaptors (booster and sustainer) come together. Might want to grind a bit
of relief in the end of each adaptor case so the hook ends are flush into the
end of the mating cases.
Did you see this? <vbg>
(There are 5 newer ones not shown. And the 6-inch is in lawn dart heaven.)
Basically, I look at it like this: They could have just said "no motors over 3
years old" period. But they allow us to fly older ones because they don't check
the date if they're on the approved (still in production) list. Still, I have
over 100 A10-0T's in my stash. Gonna take a while to whittle that down at
I didn't ask. I'm an electrical engineer - I'm supposed to know a little
chemistry - but my pyro chemistry knowledge is embarassingly lame. Basically,
it's some gray stuff with acetone :)
Pickens are even slimmer for the booster now that the A10-0T is history :-(
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD"
>>> To reply, remove the TRABoD! <<<
Kaplow Klips & Baffle: http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf
www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
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