I like both, especially the green! Rustoleum has a nice 2X green, although it's a bit light for lime green. I don't think green would hurt visibility much. At TCC it can't hurt to add a small audible beeper to the rocket to find it if/when the rocket lands in alfalfa, especially if you aren't running a tracker yet.
As for charges, I'd probably keep the main the same and maybe increase the drogue a bit (0.1 or 0.2 grams, and then +0.5 more on the backup). I usually run two 20' harnesses on rockets of this size, with the main chute a few feet back from the nose cone on the front harness and the drogue chute a few feet back from the payload connection to limit tangling. Your recovery configuration seems good, but definitely consider Onebadhawk down the road.
Looking forward to the launch!
If this thread isn't inspiration, I don't know what is!
Good luck on the testing and flights-looking forward to seeing it fly
This morning I ordered a OneBadHawk 7/16" Tubular Kevlar Harness W/ 3 Sewn Loops to replace the stock 15' tubular nylon shock cord in the booster/drogue section. Here's some pictures of the this harness I hope to have by Friday:
View attachment 291246View attachment 291247
I plan to move the stock 15' tubular nylon section to the nosecone/main chute section, replacing the stock 10' section that is too small. I may follow this up with another harness after I get a feel for how this recovery layout performs.
I loaded a cap with 1.4g 4F BP.. and used the StratologgerCF with a cheap Amazon Ematch, 1S 4.1V LiPo connected. Vacuum cleaner to simulate a flight.. applied suction, removed waited a few second (likely Mach Delay) and it fired.. but it did not shear the 4 pins and eject the main... just some smoke shot out the seams! I manually torqued off the nose cone shearing the pins and got my new chute out of harms way. It acutally got light brown spot on it through the nomex.. but is still fully functional. I'm about to repeat this same setup.. I can only think it was related to how I packed the BP in the cap with wadding on top.. else my scale is bad. More later.
I loaded a cap with 1.4g 4F BP.. and used the StratologgerCF with a cheap Amazon Ematch, 1S 4.1V LiPo connected. Vacuum cleaner to simulate a flight.. applied suction, removed waited a few second (likely Mach Delay) and it fired.. but it did not shear the 4 pins and eject the main... just some smoke shot out the seams! I manually torqued off the nose cone shearing the pins and got my new chute out of harms way. It acutally got light brown spot on it through the nomex.. but is still fully functional. I'm about to repeat this same setup.. I can only think it was related to how I packed the BP in the cap with wadding on top.. else my scale is bad. More later.
I HIGHLY recommend that you use an old t-shirt piece with the same bulk as your 'chute for ground testing. Avoids those sizzling, embarrassing issues you just experienced.
There's nothing wrong with what you did, but it's more work than a lazy guy like me likes to do. I just wire my launch controller to an ematch in the ejection charge and set it off. Your way is an end to end test, which should definitely be done from time to time.
I don't think that you should have seen a delay. I thought the Stratologger used something more intelligent than a Mach delay. That sounds more like your main charge output blew when I thought it got to your programmed main altitude.
There's nothing wrong with putting wadding on top of the BP, but it sounds like you need more BP. Without going back to read the entire thread, what's your BT diameter? With a piston, I use a full gram for a four inch body tube that's 18 inches long. That's without shear pins. The whole purpose of ground testing is to determine whether the charge size is sufficient and that the system works. Your doing all. The right things, you just need to keep redoing the test until you get the results you seek. Add half a gram each time. If something blows up you had other problems! [emoji1303]
Kevin. Just looked up my notes from my L2 with this rocket:
1.7 Rear
1.3~1.4 Fwd (4 came out hard)
That being said, I use 2 shear pins in the rear and 3 in the nosecone.
Also big +1 for Banzai88 statement on using an old tshirt. you'll get the same ground test ejection..however won't take a chance at burning your chute. I also bought the same e-matches you have. However after talking at length with a few folks at the club launch, I've decided to keep those for ground testing and use J-Tek's in the real deal. Maybe I drank the coolaide...but sure didn't want to take that chance.
Thanks for all the prompt feedback guys. Here's the details for my main chute:
4" Diam FG Tube, 14 inches between bulkplates. I calculated 15psi with 1.4g 4F BP. It worked last week with the eggtimer with GUSTO. Tonight, I had the fizzeled charge, and I just finished a second test with the same 1.4g BP, but with more careful taping and 2 pc. of wadding in the ejection charge cap to allow it to build a little pressure before the tape lets go. It came out.. but not too forceful. I had taped a few Z bends with perhaps 2 feet harness in each. One zbend unraveled, but the other didn't.. shows how weak the ejection was. So, I'm upping it to 1.7g now.. and soon to try that.
I found that the nomex cloth (Sunward) seemd more porous than the Madcow chute protector.. and thus allowed some hot gasses to penetrate the weave of the nomex. I'm putting BOTH at 12" Madcow Chute protector at the base and the 18" Sunward Nomex around the chute. Below that, I've put 3 and 4 handfuls of DogBarf. Kevin, how much Dog Barf did you put in your Main and Drogue sections.
Ok, I'm going to go look for an old shirt. I need to get this sorted out... only two short nights left to figure this out before launch day.
So, 1.7 shot the nosecone out nicely.. but for some reason, the laundry was lightly stuck in the very end of the tube.. probably about 6-12" more shock cord could have been extended.. but for some reason the laundry seemed to hang up there and not come out..perhaps the shear pins were sticking out and snagged the cloth right at the from edge of the payload.. hmm.. seems like a reasonable explainnation. I have video... I may post if I can find time.
I tested a second 1.7g 4F Charge in the nose section connected to the Stratologger. It worked fine. I used the actual chute that time, and it deployed nicely. No scorches.
Thanks Kevin. You know exactly where I'm at. I will write next to the well. I plan to do more testing of the drogue side tonight. It's somewhat concerning to have such a strong ejection with 1.4g a few days ago, and then have the same charge fail yesterday. I'll probably bump up my drogue charge to 2.0g or so, but will start with 1.7 to get a comparison. Off to work...
1. If I'm using nomex I don't use dogbarf. If I'm using dogbarf, it's because I don't have nomex with me.
2. The taped z-folds are to protect against the shock of a fast opening chute, not an oversized ejection charge. Test your ejection charge without the z-folds. It's like Goldilocks. Does your ejection charge just separate the rocket without extending the shock cords? That's too weak. Does your charge eject so forcefully that the parts reach the end of the shock cord and then bounce back to strike the rocket? That's too strong. If your shock cord mostly extends or even bounces lightly at the end, that's just right.
I don't see how shear pins could protrude into the body tube to snag the chute; they should shear right at the interface to the the coupler or NC. The long half stays in the nosecone or coupler. My nosecones all rattle! Was your charge under your parachute? If so, then you might want to find a different way to fold your chute so it's not wedged in place. It's always disappointing to see a chute snow-cone in a tube and not deploy.
[emoji1010] Steve Shannon [emoji1010]
Thanks for considering this issue and for your feedback. I'm not sure I'm confident without using dog barf, at least 2 handfuls at the moment. The 18x18 nomex in my 4" FG tube, barely covers the full length of the packed chute. Also, the darn nomex is too porous, and through the nomex I have some scorch discoloration on my new main chute. Howeve,r the Madcow chute protectors are denser weave of a fire resistance cloth that prevents the "through weave scortching". Perhaps I could try one handful dogbarf below the 18/18 nomex AND 12x12 chute protector wrapped completely around the chute. Having too much dog barf in my 4" fiberglass tube is one of my suspect reasons for having the 1.4g BP charge fail to shear Four 2-56 nylon screws.
I've had some trouble with different results for the same 1.4g 4F Black Powder charge. Last week it ejected my chute pretty aggressively, however last night a 1.4g charge completely failed to pop the nosecone off. So I'm in this "grey" problem area. I'm not sure what I'll get for the same 1.4g charge. So, I've bumped to 1.7g of 4F BP. This works pretty good.. but I was worried it might be too aggressive on "lucky" ejections.. and thus I thought a z-fold would damp out the shock when the nosecone reached line extension. It makes good sense to have those in for the main chute deployment shock as you describe.
I agree that it doesn't make sense that the shear pin remnants grabbed the laundry.. but something appears to have grabbed it as it was ejecting.. an only the nosecone shot to extend the line. There is a very small lip where the pins sheared. I'm not sure it could grab cloth or not. So, I decided I needed to re-test with the actal chute attached just below the nosecone and verify that the chute will come out with sufficient force. It does at 1.7 per my tests.
Tonight, I plan to test the drogue charge. I hope it goes smoothly.
Thanks again.
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