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Messages - greylond

Pages: [1] 2
1
Announcements / Re: Field
« on: April 04, 2020, 06:25:11 PM »
The new bridge was screwed into the wood resting on the steel I-beams. I hope that the flood merely lifted the new construction off the beams and could be picked up and carried back to the original location. Maybe secured with cables or bolts? We'd probably need four men to do do it. Securing the bridge later would need one. I'm volunteering for both.


Doug



Doug

2
General Discussion / Re: Quest Q2G2 Initiators
« on: February 23, 2020, 02:16:58 PM »
I would say absolutely. I and several fliers use dipped Chinese fireworks e-matches as initiaters. Assuming you're familiar with ohm's law, current is the issue, not voltage. My matches with the orange leads are All fire at 370 ma, All safe at 250 ma. Continuity test at 0.5 ma. Quest all fire is 350 ma, all safe is 150 ma. To my knowledge, our Wilson FX system has never lit any initiator due to continuity test.

3
Club Launches / Re: 11/02 Launch Report
« on: November 07, 2019, 08:16:01 PM »
Regarding the Modulator Cato. I found the liner completely burned away all around the bottom grain of the five grain motor. The first hypothesis of a casting tube to liner blow-by annealing the case leading to failure proves correct. The bottom grain had a ¾" core, top four grains had ⅝" cores. The blow-by may be the result of the bottom grain collapsing under G load since it had a thinner web, or just a loose fit to begin with from home rolled casting tube and liner. Two countermeasures: commercial phenolic liners and casting tubes to fit, and glue the grains to liners with Elmer's glue all max. I lost the case, but not forward closure, nozzle, or related hardware. Electronics and everything forward of the motor mount also survived. Not bad, as Cato's go. Modulator will fly again!

Doug

4
Club Launches / Re: Is the November 2nd launch still on?
« on: November 02, 2019, 08:33:42 AM »
I haven't seen a scrub announcement, I'm packed up and ready to go.

Doug Peterson

5
Build Techniques / Re: Filling 6oz fiberglass weave
« on: December 05, 2018, 04:59:52 AM »
Bondo is a polyester base rather than epoxy. I've had problems with it flaking off. I use glass microballoons in epoxy, easier to sand. My brother uses fumed silica (cab-o-sil) harder to sand. +1 for us composites! They have good prices and package smaller amounts for those of us who are'nt building entire sailboats.

6
General Discussion / Re: Forum and email are alive and well
« on: October 14, 2018, 12:02:30 PM »
Working fine for me.

7
Club Launches / THE Ohio State University project test firing.
« on: May 20, 2018, 05:27:54 PM »
I love the smell of AP and rubber in the morning. This one is a 98mm Mad River White, full N or baby O.  around 1,500 lb. thrust. Fantastic job, Gary! It even made me pee a little.


Link:      https://youtu.be/RaJgB25SSRA

8
Announcements / Re: LDRS News
« on: May 19, 2018, 09:35:30 AM »
Congratulations, Gary! I am pleased to see you have been given the opportunity to serve. Thanks for taking on the responsibility. I'm very confident your efforts will ensure that the sport, particularly the experimental propellant aspect, will be safely advocated and that the organizations as well as the public interests will be well served.

9
Club Launches / Re: Multi-Stage Rules
« on: November 09, 2017, 08:31:37 PM »
Excellent requirements! I'd recommend having a simulation ready for the RSO. Then he can verify velocity/altitude threshold for allowing sustainer ignition. The rule of thumb is at least 80% of the expected altitude when the timer expires, and at least 200 feet per second velocity when the sustainer comes up to pressure. That should keep things pointing up, more or less. Also a thrust to weight ratio of 5:1 on the booster + sustainer stack and 3:1 on the sustainer alone is a reasonable minimum.


Doug Peterson

10
General Discussion / Thrust vectoring for low/mid power
« on: November 05, 2017, 04:35:38 PM »
Dave sent me this link from ROC.

https://www.bps.space/#bio


Hobby Rocketry enters the 21st. Century! I'll be waiting for the K class system to come out......


Doug Peterson




11
Announcements / Re: Barnstorming Event + Rocket Build N Fly
« on: June 27, 2017, 05:43:14 PM »
I'm available, what class limit is the demo?


Doug

12
Announcements / Re: Tripoli Board of Directors
« on: February 21, 2017, 07:42:10 PM »
Me too! I eventually decided not to cast the other two votes because I didn't want my guy to get edged out. David told me that Gary's quite well known at ROC, and would be surprised if he doesn't get a spot. Good Luck Gary!

13
Lost and Found / Beaker went back to Muppet Labs 11/25/16
« on: November 26, 2016, 11:56:12 PM »
Disappeared without a trace, I lost GPS at liftoff. Apparently testing EX motors was too dangerous for him.

14
General Discussion / Re: How to make pods separate in flight??
« on: August 23, 2016, 11:08:28 PM »
That sounds like a great project!  I definitely want to see that one fly. I have no personal experience with parallel staging , but I am involved with a two stage tandem project with similar aspects. A couple of separation possibilities:

Pyrotechnic Fasteners, aka explosive bolts. There's an article in apogee newsletter #266.

Mechanical separation is another possibility. Eggtimer supports RC servos for instance.

In any case, you can program release by timer and tied to flight events for fail safe, such as after launch detection, but not before a set altitude or speed is reached. If the rocket doesn't reach the preset velocity or altitude within the time allowed, the boosters won't detach. That keeps it safe if something doesn't light, or worse, lights late.

I hope I was helpful, and best of luck with your project!

Doug


15
Club Launches / Re: March 12 launch what are you flying?
« on: March 04, 2016, 06:08:30 PM »
It's the first flight of a rocket deliberately designed for dynamic instability, so a small two grain H73-J to start. Probably will never see anything bigger than an I class. A rocket meant to wobble like this is likely to shred if you push it too hard. The effect is called roll pitch coupling, or more commonly, coning. This one is twice as big, but you get the idea.

https://youtu.be/k67pYfLa46U

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