L2 Certification Build -- Five Finned Folly

jlabrasca said:

Me too. I have to say, apart from learning (I think) that it is something to do lowering equipment as you descend by parachute, I didn't find much detail on HOW you use hook pile tape lowering line. I'd like to know more about this, if dhbarr can point me at a resource?



That is a real concern. The canopy doesn't catch on the hooks, but I am using a tangle-free chute with nylon netting in place of shroud lines and the hooks do snag that. The chute will be packed at the far end of the harness from the velcro, with the rolled up shock cord between. The manufacturer includes a deployment bag (the parachute is bagged in the images above) which doesn't stick to the hooks. I am not sure I will use the bag, though. I'll be flying a JLCR, so it ought to be enough to fold the canopy over the mesh. By the time the release opens, the velcro should be peeled and flapping harmlessly 4 meters away at the other end of the line <fingers crossed>.



Yeah, I'm not sure about those either <grin>. I can't sew. Two grommets at each end of the nylon strap, with the end folded over to make a loop, with the quick link through both grommets. I don't suppose it will last for as many launches as would a sewn loop, but I think it will support the weight of the rocket for few descents. How it will perform if it has to take the full shock at deployment -- I can't even guess. It might be that one or the other grommeted ends would fail before the anchor in baffle, but I kind of think its a coin toss.

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Here’s a good instruction sheet on one way to tie a loop in tubular nylon.
https://publicmissiles.com/images/tyingtubularnylon.pdf

No need to sew or use grommets. While I do like the look of a sewn harness simple knots work very well. I've sewn my own, bought some already sewn and sew on. :wink: Now I just tie a good knot and be done with it.

Finally got it on a pad yesterday (09/14/2018 -- if you are not reading this as I type it). Two fliers volunteered to witness (good and generous folks)



The day was exactly as beautiful as it looks in that shot.

Because I am a superstitious ninnyhammer I decided not to mount a camera or fly an altimeter -- convinced that the more dollars I put at risk the greater the temptation placed before an unkind Fate.

Because I am dumbass who forgot how to operate his own camera, this is the only shot of the rocket after the motor ignited and before recovery.



The J270W DMS is a wonderfully loud and bright motor. It was a satisfyingly long burn, which made the Moonbat disappear.

I flew the JLCR, but I chickened-out out and did not use the velcro shock absorber. The rocket came back ready to fly again -- so I can indulge that foolishness on the next flight.

There is an 8 mm crack on the forward side of the separation (won't call it a zipper), a little paint missing from the nosecone, and this going on at the aft end.



The wood and paper are scorched. Seeing this made me decide NOT to put the rocket right back up on the I140 DMS I had in my box. The nozzles on the 38mm DMS motors are flush with the back end of the thrust ring (no protrusion), and I think this may not be the best choice for a rocket with a recessed motor mount.

It may be CTI Pro 38 mm for the Moonbat from now on.

The baffle worked; the parachute and harness are clean, and the red cap dropped right out. So I am going to build more of those.

Thanks for the advice and encouragement.

Congrats on a successful cert flight!

Ninnyhammer may be my new favorite word.

Good show!

Congratulations!

Thanks. I am worrying now that I should have waited for the updated card from NAR before updating my sig file. *_*

I guess I should report that it went up dead-straight. The chute deployed and the JLCR worked. The leader on the chute tangled around the shroud netting (its Nylamesh tangle free chute) so it was reefed. It landed ~100 meters from the pad (estimating from the report of the step counter in my phone).

Really wish I'd flown the altimeter -- but I was having a hard time getting it to sync with my phone and was impatient to get the rocket in the air (to get any rocket in the air, its been a frustrating launch season).

Next flight, I'll get the data and some better pictures.

It sims well on the CTI J270 and J340M.

Oh wow, just stumbled across this build thread. Gorgeous work! I nominate this for a TRF build thread hall-of-fame. A beautiful, original rocket design, superbly documented, photographed, and illustrated, with excellent execution and craftsmanship. I especially the well thought out extra details, such as the velcro and the baffle.

<blush>

mbeels said:

Oh wow, just stumbled across this build thread. Gorgeous work!

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Thanks.

I appreciate the compliment, sincerely, but I decline the nomination. There are builders here who do much finer work. I will not make a counter-nomination; I am new(ish) on the forum, and no matter to whom I point somebody will know of somebody who does it better.