Doug, I'm going to download the video at work tomorrow. I'm still only dial-up here at home. 😳 Listen, my video of me destroying my test stand and upper section of a 3" rocket with 2 GRAMS is a lesson I better remember. I'll start with 2 just to be safe. I know 1.5 grams won't do it, but higher... ? Better be safe than sorry. Ken Plattner, if you read this, you wanna hold the blanket? 🙂 Actually, my launch system is automatic. I can set it for any length of time and get an audio countdown so we both could hold it. 🙄 Got good insurance? I don't think home owners covers this. ❓ Conway, I agree, most say it's better to go a little higher than sufficient with a loooonnnnnng harness. The ol' NAR axiom: blow it apart or blow it up. 😉

Bruce, I'd love to help. I'm going to be out all next week through the weekend, but anytime after I get back will work for me. Just let me know.

Ken.

You're a brave man, Ken. I won't be doing any ground testing until after Oktoberfest most likely. But I would really like your help in keeping things from blasing through fences. 🙂 I'm saving the electronics installation, ground testing, etc. for the cooler months. Thanks, and I'll let you now when the time comes.

oops, I did forget to mention that I use a piston. That will affect the charge required, all the more reason to do ground testing. Just thought you should know.

Doug

Ahhh. had me worried that i had been doing something wrong there doug. I was like how much.. wow I did that little and nothing really happens. LOL.. Yes with a piston you can use moderatly less. I on the otherhand am not using a piston. So I will need more. Thanks Doug

Doug, that was perfect, and at 0.5 grams. I noticed that you didn't use a chute. I've never tried it without one. Do you get reliable results if you don't? I mean it makes sense, tired of damages chutes! 🙄

I will probably use a small chute on the flight, just left it out for the test. For the drouge compartment I have 5" for chute space but another 9" for the coupler. When I tested at 0.3 gms it sheared the screws but couldn't blow apart the sections. After it move a total of about 7" it stopped because the the vacuum that was starting to create inside the compartment. At 0.5 gms it was just about right to gently blow them apart.

The 2 gm shot is the one I was recommending you look at. With the piston it quite easily separates the two sections...

Doug

Holy... and that was 2 grams?! That was good! From what I remember from my 2 gram event, that was about right, only I wasn't using a piston. Lots of flame to singe my chute. Quite easily separates the 2 sections? Intended understatement. You could say that. 🙂 You'd need a mile harness to absorb that easy separation. That was just so cool. 😀 I got some 4-40's at work today, and I'll drill the holes tonight. What's a good bit size for 4-40's? I've gotta go watch that again...

Not to change topics BUT has me curious. I planned on a 36" drouge chute with roughly 55 to 60lbs of rocket flying to 13 to 14k in alt. Its a Tac chute or square cut chute with no spill hole. Wondering if it may be to much. Many others directed towards.

Don't know if this will help, Conway:

http://www.washingtonhighpower.com/Chute%20Calculator.htm

I planned on a 36" drouge chute with roughly 55 to 60lbs of rocket

I have debated myself on the use of a drogue at all. I prefer not having a drogue except for one thing. I have seen drougeless dual deployments that spin the fin can until everything gets all would up and the main fails to fully open. My thoughts are to use a small (about 24" to 36") chute on the rocket also weighing about 50 pounds just to keep it from tumbling. I've also considered just a streamer for the same reason. I also plan on attaching the drogue towards the outer edge of the bulkplate instead of in the center again to keep it stable.

Doug

Thanks Doug and Bruce. Doug you hit the nail right on the head as to what my beliefs/experince is as well as what others have told me. My last project (which Dave Hanson now owns and flys) was a drougeless deployment worked great even from close to 15k. BUT it was also a much smaller rocket weighing in at 8 to 10 lbs. Not the 50 to 55 lbs my L3 will weigh. I think I will stick with the 36" drougechute. I think I will or at least should be fine.

In my first L2 attempt (bird ~6 pounds), I had the main chute stick (definitely my fault, NEVER hurry!), BUT the rocket separated and was balanced. Fell a couple of thousand feet almost flat. No problem, essentially no damage. In a well-balanced bird, a drogue isn't necessary--as JW pointed out earlier in this or another thread. Thought I was gonna find a new white fence post on the prairie. A drogue would have pulled it up, causing a nose and tail crash. You never know what works... until it doesn't. 🙁 Conway, if using a 36" drogue is what you believe will work, I bet it does. At your L3 weight, man, go with your gut. 8)

Bruce, if you are going to tap the 4/40's use a No. 43 drill. Or use a 3/32 without (taken from my old Sunstrand Machinist Handbook). Try them on some scrap pieces first though.

Ken.

For birds 4" dia and below, I use 2-56 nylon screws. I use 4-40 on some 4" birds and above.

2-56
Clearance Hole = 3/32"
Tap Hole = 5/64"

4-40
Clearance Hole = 1/8"
Tap Hole = 3/32"

Warren