- This topic has 11 replies, 6 voices, and was last updated 18 years, 7 months ago by
Bret Packard.
Bret Packard.-
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Bret Packard
I know there are varying opinions on this so lets hear em. I have exactly ZERO experience with dual deploy. My goal for MHM is to have my L2 rocket converted for a DD flight. I bought a Missleworks RRC2 last year from Jim, I have the ebay designed, the only part I haven’t figured out yet is the recovery components themselves.
The rocket should come in somewhere around 13.5 to 14 lbs. pad weight. I plan to fly either a K670GG or a K555SK. It’s a Q-tube airframe so I want to keep it below about 900ft/s.
Any way, my current thought is to go with a 24″ Tac 9 drogue from Tim, that sims out for a descent rate of about 75ft/s, then pop a 72″ Tac 9 at 800′ or 1000′. Thinking of about 25 ft of shock cord for each chute, and I am interested to know what you all think about drogues, and if you are in favor, where you would recommend attatching it. I generally attatch my chutes 2/3 to 3/4 of the way to the nose cone (or in this case the payload bay) to try and prevent the parts from banging together. Any thoughts on any of this would be much appreciated. Hopefully your comments will help me to provide good flight at MHM.
Warren B. Musselman
At that weight, I’d be inclined to pop your main at 1000′ or higher. You’ll be coming in at a pretty zippy rate with that small drogue, which isn’t a bad thing, but it will have some serious velocity. You want to make sure you give that main chute some time to open up. My 4″ bird, about 14#, bounced from an 8000′ flight with the main set at 800′. The chute came out, but didn’t open fully before impact. It wasn’t destroyed or anything, but it has taken a few bucks and a couple dozen hours to repair it properly.
Warren
Chris LaPanse
Sounds similar to my BBX, which comes in on a 20″ skyangle and pops a main at 800′. I would say you’re probably fine at 800′, but with that simmed velocity, I would probably go for 1000+, just to be safe.
Anonymous
For my part,, I think I’ve only used drogue chutes on perhaps 3 of my boosts (ever). I use streamers a lot, and I also just break the rocket and go w/o a chute or a streamer quite often. The fact that you are using Quantum tubing means you should probably slow things down a bunch, as QT will zipper.
I’ve seen absolutely enormous rockets brought down w/o a drogue of any type — but you’d best have them constructed like tanks. At LDRS about five years ago I observed a crew that flew the same rocket five times the same day, and all the boosts were big M’s. All the flights were flown without a drogue of any type, but it was a rocket that could have probably tumble recovered w/o damage :-O The rocket weighed perhaps 100# at burnout. It had a plastic coated steel cable as a shock cord. Yikes.
J
Bruce R. Schaefer
All you need to do is keep the tether (harness) of the two tethered ends up holding the thing level. As an example, my first L2 attempt, I didn’t blow the main out but the two sections separated (was a GLR Vertical Assault), so it effectively came down without a drogue–or any chute recovery at all–of course, because of that, it was rightfully DQ’d. Very minor surface damaged, which is why I love that forgiving rocket. Last time I flew it–though it’s been repaired and ready to go at our next launch, I obliterated the drogue, please don’t ask. 🙂 My L3 at MHM will have a 24″ drogue, only because I don’t know how she’ll free fall. Ideally, you want both sections to fly level and AWAY from each other. Which is why I have the WRC2 for the redundant charge, to fire if the primary doesn’t, or, using Newton’s 1st Law, to shoot the sections farther apart, if need be. In other words, you use the advice of those with more experience in high power, and your own experience… and PRAY!
MikeS
Here is my two cents worth.
I have never flown a duel. I am just about done building a duel.
My first NCR launch. I watched a large rocket take off. Big motor, Big
rush. I was soooo impressed. The rocket finished its ascent and out came
the chute. The chute I thought was tangled. It was descending very
fast and I was hoping the chute would open at the last moment. I have
had tangled chutes and the result was messy. I was feeling sorry for the builder.
Suddenly there was another event. Out popped another chute, the whole assembly reversed position and it landed softly on the ground.To me it was almost magical to watch.
http://www.putfile.com/pic.php?img=4962503
Drogue or No Drogue?
Motivation – Motivation
I am building my HyperLoc 300 to specs. and following the instructions
and see how it flys..Bret Packard
OK, I’m pretty set on using a drogue at this point, so if anyone has ideas or opinions on the best attachment point that would be awesome. Main focus is to keep the two parts from banging into each other and/or tangling.
Bruce R. Schaefer
OK, I’m pretty set on using a drogue at this point, so if anyone has ideas or opinions on the best attachment point that would be awesome. Main focus is to keep the two parts from banging into each other and/or tangling.
Batman, wait for JW’s response on this, or Warren’s, but using my Vertical Assault as an example, it is balanced in weight and length, so the drogue would be put in the middle of the harness. It just depends on how she flies in free fall. And you won’t know that until you fly it. From the maiden flight, you’ll know IF you need a drogue and what place on the harness to attach it. On my upcoming L3, I have NO IDEA how she’ll fall in free flight, so I’m going center, since both sections are pretty close in weight, though aerodynamically different as night and day. I won’t know how things will fall until I fly it. PLUS I’ll be using a small drogue (24″) and 60′ of harness between the two sections. That’s my 2 cents. 8)
Warren B. Musselman
I mount the drogue within 2′ of the end of the booster section and the main 2/3 of the way to the nose. My booster shock cord is typically 2 or 3 times the total length of the rocket and my main shock cord is typically 3 to 5 times the total length of the rocket.
Warren
Bruce R. Schaefer
My booster shock cord is typically 2 or 3 times the total length of the rocket and my main shock cord is typically 3 to 5 times the total length of the rocket.
My booster separation will be at 60′ separation, and my main at 40′ for a 12 foot rocket (although I can lengthen the main separation after ground testing, if need be. I won’t know until I do the ground testing.). You see, Batman, there are so many differing opnions–as you said when you posted this thread, and each original rocket is different. There are no right or wrong answers (well, there are, but only you will know that after a flight); it’s you and your rocket that have to make the decisions. I have made some really stupid mistakes and learned from them, but as you move up, you can’t afford to make as many as you did at L1 (well. maybe not you, but me 🙂 ). I tend to go long on harnesses. If you can cram them into an airframe and blast them out, you’re okay and separated. The only failures I’ve had as far as harnesses is them being too shart. There really is no luck in this. If you’re doing the wrong thing, it will catch up with you. The great thing about this club is that we are all on our own journeys in this, but we stick together and advise each other. Good thread. 😉
Bret Packard
Warren B. Musselman
Chris LaPanse
Anonymous
Bruce R. Schaefer
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