Build Thread: LOC/Precision 3" Iris 38mm. "The Comeback Kit". First build in 20 years!

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Mach_Seven

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Recovery set-up.
This is the basic layout. Please let me know if you see any issues with this design. One question i have is: should i bundle the 5’ leader for the parachute in with the JLCR? If I don’t, I’m concerned about it getting tangled with the streamer. Daddy wants her to get home safe...

JLCR for chute.

15’ streamer fo visibility.

Will be upgrading to 42” or even 48” parachute.
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Mach_Seven

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Complete re-design of recovery system. Final assembly.

It's been a while since my last update. I didn't feel I was getting the recovery system right and put a lot of thought and research into how to make my desired configuration (JLCR/streamer) work reliably. Part of this research included attending the launch of my soon-to-be club: Spaceport Rocketry Association. I wanted to watch closely how rockets fall through the air with reefed chutes and streamers. Two HPR launches included both.

Of the two, one recovered successfully with the streamer about a third of the way down the shock cord. It was a 3" rocket similar in size to the Iris. The second was in the reverse configuration with the streamer at the nose cone section and the chute down the shock cord. This was a much larger rocket flying on a K motor. The large streamer kept the rocket falling with everything in a vertical line. When the chute release opened, the streamer fell into the shroud lines and snarled the chute for a hard landing. This, combined with my other research, convinced me my instincts are correct in putting the chute at the forward airframe.

I also eliminated 3 quick links by having an honest-to-God cobbler sew my shock cord loops and two sewn on swivels.

This is just a mock-up. I'll tighten things up after testing and before launch. By all means, point out any problem areas you see.

Apogee Deployment via RRC3 - Motor Ejection as Backup - Streamer at Apogee - JLCR Releases 42" Chute + 5' Leader at 600'


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That nylon strap is slippery. It doesn't pass the shake test. Any suggestions?
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"Orderly in, orderly out" I've been told. (That's 30' of shock cord, by the way. Change my mind.)
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Ejection charge testing on deck.
 
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Mach_Seven

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Av Bay Assembly

Never used electronics on a flight before. The switch hole is huge because I was initially going to put the camera there. And yes, as a matter of fact, I WAS drinking when I made those cuts.

Initial power-up of the RRC3:
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Vent holes also drilled in booster section and forward av bay bulkhead.
 

richP

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Personally, I'm not a huge fan of having the main and drogue flapping around together on descent, so not sure how well that works out. Could be fine, but also the possibility of entanglement.
Otherwise, I think you could cut back on the tape a little, it is a fairly light rocket. I've used size 8 rubber bands (the little ones) to hold the cord together but release easily.
 

Mach_Seven

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Personally, I'm not a huge fan of having the main and drogue flapping around together on descent, so not sure how well that works out. Could be fine, but also the possibility of entanglement.
Otherwise, I think you could cut back on the tape a little, it is a fairly light rocket. I've used size 8 rubber bands (the little ones) to hold the cord together but release easily.
Will do. Thanks for the input. I guess I should listen to the guy with an Iris for an avatar.

As for the streamer and chute out together, my unscientific observations (albeit careful ones) told me that in this configuration, the reefed chute and nosecone section create a drag that puts an opposing force on the drag of the streamer which keeps the shock cord between chute/streamer taut. This makes for a clean deployment. The one that I saw fail was in the reverse configuration.
 

thzero

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Was going to chime in on the tape... I typically have used painters tape instead of masking tape. At least my understanding is tape keeps chords orderly for deployment, and supposedly help reduce "snap".

How long if streamer are you using and what width?
 

Mach_Seven

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Was going to chime in on the tape... I typically have used painters tape instead of masking tape. At least my understanding is tape keeps chords orderly for deployment, and supposedly help reduce "snap".

How long if streamer are you using and what width?
I used more tape than I would for flight just to keep it together while i messed with it. The streamer is 4”x15’ bright orange polyester.
 

Mach_Seven

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Ok... Sourcing? :)
I got it in the Hobby Lobby fabric section. It’s called a “blanket binding”. I think it’s used to put tose nice edges on blankets. It had a hard crease down the middle but it ironed out easy enough.
 

Mach_Seven

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Live ejection charge test with rocket packed for flight! Will he blow it out or blow it up? Stay tuned!


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DMehalko

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Looking good! I flew a i280 last weekend in my goblin, sweet motor and good choice!
 

Mach_Seven

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Looking good! I flew a i280 last weekend in my goblin, sweet motor and good choice!
Maiden flight is April 17th. The on-site vendor has an I280 literally with my name on it. The problem right now is dry season. The drought index has to cross a certain threshold before we can use sparky motors. Hoping for rain between now and then.

Question about that motor: I didn't select it just because it's cool, but because I want this rocket to get moving quickly off the pad to overcome it's slight over-stability and the I280 thrust profile looks ideal for this. But I've watched several vids of this motor in use and it seems in almost every one the rockets "whip" off the pad or weathercock severely. Is there a correlation between the two? I can't see how the motor would cause that, yet it was a common theme in the vids.

That motor stays above 300 n/sec almost it's entire burn. That should get my 5 pound rocket out of town pretty fast, shouldn't it? How did your Goblin fly?

Fun Fact: The I280 spikes to 78 lbs. thrust at ignition and levels off at 68 lbs. until a rapid taper-off.
 
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DMehalko

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Maiden flight is April 17th. The on-site vendor has an I280 literally with my name on it. The problem right now is dry season. The drought index has to cross a certain threshold before we can use sparky motors. Hoping for rain between now and then.

Question about that motor: I didn't select it just because it's cool, but because I want this rocket to get moving quickly off the pad to overcome it's slight over-stability and the I280 thrust profile looks ideal for this. But I've watched several vids of this motor in use and it seems in almost every one the rockets "whip" off the pad or weathercock severely. Is there a correlation between the two? I can't see how the motor would cause that, yet it was a common theme in the vids.

That motor stays above 300 n/sec almost it's entire burn. That should get my 5 pound rocket out of town pretty fast, shouldn't it? How did your Goblin fly?

Fun Fact: The I280 spikes to 78 lbs. thrust at ignition and levels off at 68 lbs. until a rapid taper-off.

Interesting, ya weathercocking is typically an over stable scenario and/or a lower thrust to weight ratio. My goblin flight was killer and a super awesome motor, ripped right off the pad and tracked perfect, i suspect you will have no issues :).
 

Five

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Watch landing descent rate. With those big fins right at the back they are vulnerable. My Loc IRIS 2.25" maiden flight came down on the farm road for our launch site. Cracked a fin. Now fixed, but I increased parachute size from the LOC supplied one quite a bit.
Landing:
View attachment 449088
Damage:
View attachment 449078
Loc always sends a smaller parachute. I always have to buy a bigger one. Im starting to wonder if they do that purposely.
 

cwbullet

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Welcome back to burning your cash.
 

Mach_Seven

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Welcome back to burning your cash.
I'm over a grand in and haven't even flown it yet. But I used to have a drug problem so I just tell myself, "You've blown way more just partying over the years..."
 

cwbullet

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I'm over a grand in and haven't even flown it yet. But I used to have a drug problem so I just tell myself, "You've blown way more just partying over the years..."
Sounds like a problem.
 
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