L2 test question-pool - clustering BP and AP

I've clustered BP and APCP motors on several occasionsin an Estes FatBoy. Lit the F39 APCP motor on the pad and used thermolite to start the six C6-7 BP motors in the cluster. Works great.

If you have some suggestions for the L2 test pool questions, you can direct them to Carl Tulanko. His contact information in on the NAR website.

John Lyngdal NAR Trustee

Since the questions are arbitrary and the above example relies on materials that are no longer readily available, have fewer questions and rely almost entirely on the fligh texperience?

Jerry

Bit,

I upscaled a Little Beth X-2 (see:

Yes:

Chris Eilbeck's 'Slight Niggle' - H180W and 6 (poss more) D12's

Darth Maul's Revenge by Marc Casanova:

Why not :-p

Additional challenge? If you're talking MPR, then the larger Estes motors would go well with EFG motors. You might want to cluster a Pro38 G and some BP....you could put the BP motors in outboard/strap-on boosters etc. Cheap fun I guess :)

Quickmatch the BP motors from the AP motor. Probably a better approach is to work out how to ignite the AP motor quickly.

OR

Use an AP motor with enough thrust to safely lift the rocket and light the BP motors with a G-Wiz, timer etc, either at launch detect or burnout.

With Pro38 motors - very little time I would think.

To assess that one is generally knowledgeable about rocketry? If you're an RSO (to be a UKRA RSO you have to take the L2 test which is broadly similar and contains this type of question) and someone comes to you with a mixed cluster, you need to know what to do and what questions to ask.

HTH.

So you didn't use any special delay techniques to assure that the APs ignited first, right? Just hit all 3 igniters at the same time?

I remember that quite well. Cool rocket. But being under the check-in tent, I didn't get to see the flight.

I usually volunteer to be SCO at these launches so I can meet folks and see cool rockets.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

yes.

Cuz it's cool.

Ignite the core AP motor conventionally. Use thermalite in the exhaust or onboard electronics to ignite the rest. IIRC the last time I did this was just before FSI certs expired. I loaded up a LOC Ultimate with an H180-MW, 2 F100s and 2 F7s and maybe 2 more something else. The H180 ignites on the pad, and all the BP motors shortly afterwards. Great fire and smoke, great flight, until the rocket drifted off into the Bong swamp... Electric fences are such fun when you're knee deep in the swamp.

You don't, you use the ignition of the core to cause the ignition of the rest of the motors.

IIRC the actual question is "Which will light first", which IS something you should know, even if you never try it.

I was one of the folks who reviewed the original batch of questions for the NAR. Trust me there were some REALLY bad questions on the list. At least last time I looked, they don't renumber the questions, so you can tell where bad questions were pulled by the numbering gaps. And it's been even longer, but the TRA test has some just as absurd questions. Everything about hybrids is meaningless to any one who doesn't fly them.

Of course, this reminds me of the test I took for my Technician Ham license in 1976. Many questions on vacuum tubes even though they just weren't very common even back then. Nada on anything solid state. I wonder if this has changed even today :-)

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

First time, every time.

I've never seen it, but that doesn't mean people don't do it.

That question is valid for a LOT of what people do in this hobby. Most often, the answer is "because they can", or "because they want to and it makes them happy". Either one is quite valid -- that's the fun of this hobby, there's enough variety to keep almost anyone happy.

I'd use electronics, with a G-switch-based device that sent power to the BP igniters as soon as it sensed movement from the APCP motors.

Without lots of testing so you know your system and your igniters with specific motors, you can't.

Because it demonstrates some knowledge of startup characteristics of motors, is my guess. There are lots of things that are "fringe" to people who don't do them, but the question pool has to cover everyone, and demonstrating at least some knowledge of a diverse range of topics is a good thing, I think.

-Kevin

Thanks - reasonable answers, as were most this time. :^)

Bob you can take the new modern ham tests here.

cool no ?

I've done it lots of times. Sometimes in a traditional cluster rocket, sometimes with the BP motors in strap-on boosters while using a composite motor for primary thrust.

It's fun! :)

Usually, the BP motors are air-started. This can be accomplished either with fuse such as Thermalite, or with a timer or other electronic device.

With the above methods, the ignition delay is controlled and can be anywhere from "at first motion" to several seconds after liftoff.

Clustering BP and composite motors isn't all that unusual, and expecting both types to light at the same time is a fairly common mistake.

Coeme to think of it, the Pro38 motors are probably the one type of composite motor that could be ignited simultaneously with BP motors. They use a pellet of BP to boost ignition, and light darn near instantly.

Of course there's the option I use to use when I was younger (much). Ignite using 120V AC. Almost instantaneous ignition on just about anything. But you probably don't want to use a stock launch system.

Don't try this at home, kids.

Yes.

And vacuum tubes are still used in linear amplifiers.

Glen, kc0iyt

Yep. 'Empty state' still offers the best bang for the buck for high-power amplifiers (more than a few tens of watts).

The downside is that you need a high-voltage power supply, which adds complexity to the equipment, but is getting to be a lot easier than it used to be. The kinds of power conversion that are available (and cheap) today never cease to amaze me.

The Extra-class ham radio exam (I'm studying for it now) has a lot of questions on FETs of all varieties, some on bipolars and diodes, and next to nothing on vacuum tubes as far as I can tell.

MJ, retired NAR Trustee NAR #14025 (1969) L1 (1993) Amateur Radio WB9QLR (1975)

Trivia on vacuum tube durability: Back in the early 1940's the US (and presumably everybody else) developed the first proximity-detonating AA shells, mostly 88mm diameter. These little gems used a simple radar set in the artillery shell. The RF section was, of course, vacuum tubes - sufficiently hardened to survive a 10,000-G launch shock, or thereabouts. So don't tell me vacuum tubes have to be inherently fragile :-).

Vacuum tubes can be made with metal, instead of glass.

Once again, thank you for your service.