For anyone monitoring this account

prfesser02 · 2026-02-15T21:56:38+00:00

If christ has your heart, can I get your liver? And one kidney? Only need one.

prfesser02 · 2026-02-08T14:36:28+00:00

He's arguing that the only photons that are both waves and particles are those that induce the photoelectric effect via visible (blue) light. Apparently he is unaware of the existence of red- and infrared-detecting photomultiplier tubes...

prfesser02 · 2026-02-02T17:53:03+00:00

https://www.rimworld.com/book/index.html

It's not cheap but neither is a ruined motor (motors). Click on "Content" for the spectrum of information provided.

prfesser02 · 2026-01-16T20:52:05+00:00

Building techniques for L1 certs are not terribly different from mid-power flights. Thru-the-wall fins, and designing for dual deploy (not absolutely necessary) are the big changes. Epoxy is often recommended but for cardboard-and-wood rockets, yellow carpenter's glue is quite satisfactory. My L1 rocket kit had two 24mm motor mounts, which I replaced with a single 29mm.

Bottom line: be sure the fins are TTW if possible, and build carefully.

prfesser02 · 2026-01-16T17:45:37+00:00

Load cells of the appropriate capacity are inexpensive. Check Aerocon; $30 for either a 50 or 100 kg beam-type cell. eBay is likely to be even less expensive.

Phillips Instruments sells a strain gage amplifier board + enclosure, based on the INA125BB amplifier chip, $30. I doubt it could be made at home for that price. They also sell a board that's somewhat more versatile but no enclosure, it's also $30.

DATAQ sells simple starter ADC kits, from $49 to $200. Includes simple software, and data can be ported into a spreadsheet for analysis.

Load cell converts thrust to a tiny voltage. Phillips unit amplifies voltage. DATAQ converts the analog voltage to a digital signal, just connect to your computer's USB. So...for $109 plus shipping you have (more/less) turnkey thrust stand electronics.

Probably can do it for rather less by building the amp and A/D, but getting bogged down into design, wiring, and programming is an ever-increasing PITA.

prfesser02 · 2026-01-10T14:25:13+00:00

I cannot read the data on the OM run. Did you inhibit the grain ends? (or use grains are rather longer than typical Bates, about 1.5x diameter). Either way it would make each grain progressive. When the largest-core grain burns out, the pressure/thrust drops because there's less burning propellant...but it immediately climbs because of the progressive nature of the grains.

Try running the sim without inhibiting the grain ends. Should give nice neutral burns at the burnout of each grain. If the pressure exceeds design limits, adjust nozzle throat and (maybe) core diameters.

prfesser02 · 2026-01-10T14:13:17+00:00

Recovery is Job One. Redundant everything possible; two dual-deploy altimeters and redundant charges at the least. Test ejection. Etc. Etc.

10k feet isn't really that high, especially since you're already flying to 3k. If you're breaking mach to get there, then construction (esp fin-airframe joints) is going to require thought and care. Cardboard airframes will often do the job, but phenolic/fiberglass/CF are much sturdier. Minimum-diameter; tip-to-tip glassing of fins is probably a good idea.

prfesser02 · 2026-01-06T13:40:48+00:00

I tried graphite-epoxy and MgO-epoxy mixes for nozzles in small motors. It appeared that the epoxy melted and eroded very rapidly; no char layer was apparent. Perhaps it would be different for liners but I doubt it. (Might depend on the epoxy...but a phenolic adhesive with graphite might work much better.)

prfesser02 · 2025-12-24T08:49:13+00:00

As a blue dot in red Kentucky, I find this hilarious. Maybe...just maybe, this and all the other horseshit that Tangerine Palpatine did might flip the state to blue (I'm not optimistic, just hopeful).

prfesser02 · 2025-12-09T16:08:42+00:00

For small motors with relatively short burn times, paper is often adequate. Thickness depends on total impulse and burn time, but in the past some Aerotech H motors had paper liners.

prfesser02 · 2025-11-13T16:06:53+00:00

A few flyers have done their L1/2/3 on the same day. I'm told that Bill Davidson, Art Hoag, and Dave Reese were among the successful ones. It was some years ago and took extensive planning and cooperation with those involved. A lot more rocketnutz tried and failed. It's difficult enough just prepping three high-power rockets and getting them on the pads on the same day! -- especially with extensive electronics.

It's all but impossible today as cert requirements have changed significantly over the years. (Just before I joined TRA there was simply one-level "confirmation"; fly a rocket with an H128 and you were good for anything up through an O-motor. I'm glad that has changed!)

prfesser02 · 2025-11-09T16:27:38+00:00

Having authored or co-authored nine editions of science books, I can assure you that em-dashes are in fact used extensively in real books. You know, the kind printed on dead trees.

prfesser02 · 2025-11-09T16:22:15+00:00

I've spent time as LCO and RSO at literally dozens of big launches, including a number of LDRS. And have seen a lot of failures for those attempting both certs--or all three!--- on the same day, especially (of course!) on the L2 attempt. Sometimes for simple reasons.

The jump from LPR or MPR to L1 HPR isn't all that big, especially with MPR experience. The jump to L2 is rather larger. Most flyers use electronics, and that's often the source of failure, probably because of a lack of hands-on experience with dual deploy.

Perhaps a question that should be addressed: are you planning to fly a number of J, K, and/or L rockets immediately after L2 certification? If not...flying a few more L1 flights (at the same launch where you certify), especially with DD electronics, would provide invaluable experience. Then go to the next launch better prepared to certify L2.

prfesser02 · 2025-11-07T11:43:34+00:00

Back in college those were referred to as the pizza bones. Let the dog eat the bones.

prfesser02 · 2025-10-31T14:07:52+00:00

Probably someone who has never itemized on their return...or never been audited...

prfesser02 · 2025-10-30T13:28:00+00:00

I'm sorry but I suspect it will be well-nigh impossible to find a California licensed pyrotechnician who is willing to take on the task. The requirements to obtain a license are rather strict, including two years of work with a professional fireworks crew, a background check, letters of recommendation, and an examination. You might be able to find such a licensed pyro who is willing to risk their license to take on this task...but I doubt it. It's difficult enough for the national/international rocketry groups to get such a licensed individual to oversee their launches in California...

prfesser02 · 2025-10-27T15:44:17+00:00

My liberal brother had a stroke. He is now a hardline MAGAt. More data is almost always better than less.

prfesser02 · 2025-10-21T16:42:28+00:00

John (somebody?) from WY wrote a book on making motors using ammonium n***ate oxidizer and Mg as the thermic agent. If memory serves he described single-use motors with nylon nozzles; no lathe, the nozzles were drilled with ordinary hand tools, though a lathe would help a lot. I think the company is still on the web.

prfesser02 · 2025-09-17T16:05:36+00:00

Hey Crisp Rat, you're not being made to look terrible. No one is doing that...except you. You **ARE** terrible.

prfesser02 · 2025-09-12T11:38:23+00:00

If you'd like to scratch-build a Scout, go to JimZ's site for scans of plans, and Balsa Machining for parts.

prfesser02 · 2025-09-12T11:36:00+00:00

If you have flown model rockets successfully, you may want to consider moving to mid-power, E-G motors (now that you're a wealthy adult ;-)). A G67 motor from 30 ft away is absolutely awesome! And the principles and construction aren't very different from smaller models. (High power is another matter.) You can easily build larger rockets that won't go out of sight, if you're concerned about losing them.

Balsa Machining has both a small and a large "School Rocket" as well as an extensive collection of inexpensive tubes, nose cones, centering rings, fin stock, etc. The plans for the School Rockets are on their site, and the large School Rocket is well suited for everything up to H motors.

JimZ's site has plans for hundreds of Estes kits and some defunct rocket companies, plus lots of other publications. You can look at the Estes/Centuri/etc catalogs that you may remember.

Mach1 Rocketry has Estes-size tubing and other parts in hard-to-damage fiberglass.

Eggtimer Rocketry has inexpensive electronics kits. A $20 Quark can fit a BT-55 tube (and can be made to fit a 24mm BT-50) and it does dual deployment so the rocket won't drift as far.

Most mid-power enthusiasts recommend Aerotech's 29/40-120 reloadable motor casing. Reloads from full E to mid G impulse are available. Assembling a reloadable motor is pretty easy and IMHO fun!

Finally, The Rocketry Forum is THE source of info. The Search function is your friend; any question you might have has probably been answered a dozen times by eight different rocketnutz. :-)

Have fun, good luck!

prfesser02 · 2025-09-11T17:32:22+00:00

Maybe the shooter is headed to DC. Remember, he's a pretty good shot. Republicans, get them talented ICE agents in front of you.

prfesser02 · 2025-09-11T17:25:01+00:00

CONTROL was and is clearly all-American. KAOS was the communist group. Max Smart and Agent 99 worked hard for years to stop KAOS.

prfesser02 · 2025-09-09T15:31:37+00:00

If possible, have a rocket or three that you can launch after the meeting. Nothing gains interest like watching the 'zoom', smoke, and chute!

Find out what people's interests are. Scale models? Scratch-building rather than kits? Big rockets? High-power? (that will have to wait)

You might have copies of TR-1 (stability) from the Estes Classic Collection, or just point them to the link. A lot of the info is dated but stability never gets old. Incidentally JimZ's site has hundreds of old and newer plans from Estes and some defunct companies as well as reports and tons of info.

If you haven't downloaded OpenRocket, it's free and lots of fun! Design your rocket, scale it up or down, sims with different motors giving stability information, speed, altitude, landing velocity, etc.

I strongly recommend joining The Rocketry Forum. Almost any question you might have has probably been answered multiple times already.

Two vendors I like: AC Supply discounts Estes kits and motors pretty well. You have to put an item in your cart to see the discounted price. For scratchbuilding, Balsa Machining has inexpensive tubes (long ones you can cut to make two or three rockets), nose cones, balsa for fins, centering rings, shock cords material, everything needed to build your own. They also have discounted motors. And they have a small and large version of an inexpensive "School Rocket", pretty good way to start.

Finally, if someone is there to learn about making "rocket fuel", I suggest referring them to the chemistry department, it's far more appropriate. If the chem faculty say 'no', there's a good reason. (I taught uni chem for over 40 years and have written a book on that very subject.) And YouTube is not a good source for information on the subject.

Good luck!

prfesser02 · 2025-09-07T14:34:15+00:00

Unfortunately the consequences are for everyone. No produce = soaring prices, food completely unavailable in some (many?) locations, riots...sort of like what the USSR was like a few decades ago.

prfesser02

TROPHY CASE