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  1. prfesser

    Diy E-match or igniter

    Mine have not degraded quite that fast, but they do degrade after a year or so. Though they seem to be usable on a 12V system for a couple years afterward. I don't solder at all. And I wrap the nichrome at least 8 times around the copper, usually 10 or more times, tightly, for maximum contact...
  2. prfesser

    Returning to rocketry after 25 years. Central Indiana.

    Welcome! If you haven't already seen it or heard about it, OpenRocket is great fun and is absolutely free! Build a virtual rocket, insert a virtual motor, see how high she'll go, best delay time, top speed, speed off the rod/rail, etc. If you're building a kit you'll probably be able to find a...
  3. prfesser

    hi

    Welcome! Bluegrass Rocketry is in Elizabethtown and flies about every month. Music City Missile Club was flying out of Hopkinsville but it sounds like that field is going away. ☹️ Another possible flying field about an hour east of Hoptown, we'll find out more later. Where are you in KY?
  4. prfesser

    Dad returning to model rocketry after 30 years!

    Welcome! There's a new tool in town, he's called OpenRocket, and he's absolutely free! Build a virtual rocket, insert a virtual motor, see how high she'll go, best delay time, top speed, speed off the rod/rail, etc. If you're building a kit you'll probably be able to find a file for it, there...
  5. prfesser

    New to the group

    Welcome! There's a new tool in town, he's called OpenRocket, and he's absolutely free! Build a virtual rocket, insert a virtual motor, see how high she'll go, best delay time, top speed, speed off the rod/rail, etc. If you're building a kit you'll probably be able to find a file for it, there...
  6. prfesser

    Rms delay elements

    A delay in intimate contact with another delay should almost certainly ignite in these conditions. The pressure drop, if it's an issue, occurred when the first delay ignited. Close to atmospheric pressure after that.
  7. prfesser

    Rms delay elements

    Kosdon and Loki motors use a stack of o-rings on the delay. I expect that a single roring would allow some gas to slide by. The delay elements in this scenario would presumably be rather short, but if they're long enough perhaps two or three o-rings could be placed around each element.
  8. prfesser

    What I did today -instead- of Rocketry.

    (Yesterday) Pain Management, talked to an actual MD. If I understood him correctly, they may be able to do some injections for my neck, but not for the arm, or at least not until I can get off the blood thinners (November). So it goes. Also got groceries at Aldi's which we don't have in Murray...
  9. prfesser

    Attic ladders, advice and recommendations needed please

    We have a wooden ladder (older house). Get metal. [Need wobbly-legs imoji here] Otherwise I conditionally agree with @3stoogesrocketry; a stepladder is a lot less work if access is very infrequent. However...lugging/pushing a heavy load up a stepladder and lugging it up a ladder that's attached...
  10. prfesser

    New New Zealand model rocketer

    Hi and welcome! FWIW there are several forum threads on papering fins. Makes them heavier but a lot easier to get a smooth finish.
  11. prfesser

    Light Fuse, Get Away...

    And then you have the one who's not merely stupid, but deliberately stupid.
  12. prfesser

    Wanted Tripoli 10 year pin

    TRA HQ should handle this. Side note: I was surprised. Your number is 5333, mine is 4096, but 15 years between us, as I should get my 30-year pin now. Apparently TRA's membership rate in recent years is significantly greater than of early years. Good.
  13. prfesser

    Tasco 11T telescope help?

    Probably true. But there is a special kind of "yee-HAW!" when you manually find an object. And along the way you learn just how FREAKING BIG the bloody universe is!! Trying to find a sky object by scanning, or by moving just a full-moon-width at a time---one of the methods used in The Land Of...
  14. prfesser

    Tasco 11T telescope help?

    Just want to confirm that it's a reflector. (115mm would have been a pretty big refractor for way back when). 0.965" was the standard for most Japanese scopes for some years. Surplus Shed carries some fairly decent inexpensive optics, including a few in 0.965" (orthoscopics were the standard for...
  15. prfesser

    What I did today -instead- of Rocketry.

    Took Dale (one of the outdoor cats) to the vet yesterday, post haste. He showed up under the back porch. Been absent for over a week and either was poisoned or got something bad to eat. Very high bilirubin and a few other markers that were above normal, dehydrated, listless. He's somewhat...
  16. prfesser

    Sprint: Zero to Mach 10 in five seconds

    Reality: ABMs would not have protected much of anything, regardless. When nuclear overkill capacity on each side greatly exceeds common sense, any ABM would allow at least a few warheads to reach their targets. With ten or more Big Booms per ICBM, and Odin-only-knows how many ICBMs....... An...
  17. prfesser

    Sprint: Zero to Mach 10 in five seconds

    Sprint (the interesting stuff starts around 23:00) was our attempt at an antiballistic missile system (shorter summary here). Not enough time to open a hatch; Sprint destroyed its silo cover upon launch. First stage 1.5 second burn; Sprint heated to incandescence during 2nd stage burn.
  18. prfesser

    Watch how serious the poor anchorwoman's face gets about "Rocket Fuel"

    "Potassium nitrate exp***ive mixtures" is on the list. The phrasing is such that a mixture containing KNO3 can be deemed "an exp***ive", regardless of whether or not it actually IS one. And before anyone suggests another BATFE battle over sugar propellants...be aware that removal of APCP from...
  19. prfesser

    What did you do rocket wise today?

    Steam is used to heat the polystyrene beads, but the preferred "blowing agent" for expansion appears to be pentane.
  20. prfesser

    National Food Celebration Days

    Is a scam. IMHO it should be National "Poke-A-Divot in the bottom so you can find and skip the cream-filled ones" Day :) I always looked for the caramels and the nut fillings.
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