[NRVR-Members] L3 Build Techniques

Sat Nov 26 23:39:29 CST 2016

Low and slow - don't pick a massive M motor for your very flight.  Obviously keep at least a 6x1 thrust/ weight ratio, but small motor, dual electronics, simple "midship" e-bay design all apply to the KISS principle 

Small drogue chute attached directly to the nosecone to help pull out and inflate your main - or similar deployment bag technique is recommended 

To help with the stress you are worried about re: bulkheads and harness attachments, use at least 4x rocket length of harness.  When you use longer harnesses, you need drogue on nosecone.....

Chris

> On Nov 26, 2016, at 22:26, Thomas Tweeks Weeks <tweeks-junk2 at theweeks.org> wrote:
> 
> Thanks for the feedback Bob.. Everyone seems to agree. KISS.
> 
> Peter mentioned doubling up on the CR. That sounds like a good idea. Talking to the guys at Mad Cow too.. since I'll mainly be flying it on 54 and 75mm, they said that many of those motors are going to have no motor ejection to speak of anyway, and that I could also just make use of a threaded forward closure and forged eye mount point. I think I like the idea of having either of those options to choose from.
> 
> I also really like Peter's idea of reinforcing the upper CR with a few inches of fiberglas coupler tube epoxied butt up against the upper CR too. great KISS way of beefing up that pressure point.
> 
> I wanted to also make use of a thrust plate on the tail of the rocket, but the boat tail section of the bird I selected doesn't appear to allow for that. Oh well.  I don't need the extra mass aft anyway.
> 
> Thanks again guys. Great tips. I think I'm finally ready to splurge and pick up some West Systems now.  Maybe I'll bring in sections of my build to a future meeting.
> 
> Tweeks
> 
> On Saturday, November 26, 2016 8:25am, "Bob Schoner" <bob.schoner at gmail.com> said:
> 
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>> I am not a fan of using
>> threaded rods through centering rings. Unnecessary
>> extra weight and questionable added value. I have never seen a rocket fail
>> in a way that threaded rods would have helped. Proper surface prep with 40
>> grit sand paper, good epoxy (not 5 minute hobby store stuff) is more than
>> enough. If you want more centering ring security at the top glue a 3"
>> section of coupler and fiberglass it to the recovery centering ring.
>> 
>> If the right materials and techniques are used I don't feel TR adds
>> anything but extra weight. That is just one opinion. Let's hear some more.
>> 
>> Bob
>> 
>> Congrats on your Black Friday score!
>> On Sat, Nov 26, 2016 at 1:14 AM Thomas Tweeks Weeks <tom at theweeks.org>
>> wrote:
>> 
>>> Hey all..
>>> 
>>> 
>>> 
>>> So I'm finally going L3... (partially thanks to Black Friday). I'll leave
>>> what I'm building a surprise.. All I'll say it that I chose a 75mmt kit
>>> that will let me cert L3, but also adapt down to 54mm and fly this bird at
>>> our monthly launches too.
>>> 
>>> 
>>> 
>>> That aside, I did want to get some of your (current L3s) suggestions and
>>> lessons learned from your L3 builds (and other large project).
>>> 
>>> 
>>> 
>>> There's one interesting TRA guy I've been following on Fbook who's got
>>> some pretty cool fincan construction and build ideas.. thought some of you
>>> might want to check them out and comment. I'm all ears on your big
>>> suggestions and lessons learned. Check it out:
>>> 
>>> 
>>> http://www.rocketryforum.com/showthread.php?131007-Level-3-Build-Rocketry-Warehouse-Terminator/page2&s=6803a5849819c8603a81a48356c32a73
>>> 
>>> 
>>> 
>>> He uses an interesting three thread-stock rods to pass the recovery forces
>>> down through the forward centring ring down to the lower CR too (or thrust
>>> plate if you have one). Pretty cool.
>>> 
>>> 
>>> 
>>> But if you look at his pictures, he also perforates his forward CR a total
>>> of five times.. something that makes me nervous. Especially all the force
>>> on just one side of the MMT's CR. Seems more risky.
>>> 
>>> 
>>> 
>>> I was actually thinking about doing something similar but using a two
>>> super long thread-stock rods and U-bending them form U bolts (four rods)
>>> that run the length of the entire MMT.
>>> 
>>> 
>>> 
>>> See crude diagram:
>>> 
>>> http://theweeks.org/rockets/PICS/L3-MMT-rods.png
>>> 
>>> 
>>> 
>>> Thoughts? Ideas?
>>> 
>>> 
>>> 
>>> Tweeks
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> 
> 
> 
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